Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2017 shares
Document and Entity Information [Abstract]
Entity Registrant Name	ProQR Therapeutics N.V.
Entity Central Index Key	0001612940
Document Type	20-F
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding	31,921,865
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY

Consolidated Statement of Financial Position - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Intangible assets	€ 39	€ 90
Property, plant and equipment	2,505	3,438
Non-current assets	2,544	3,528
Social security and other taxes	396	395
Prepayments and other receivables	2,064	2,420
Cash and cash equivalents	48,099	59,200
Current assets	50,559	62,015
Total assets	53,103	65,543
Shareholders’ equity
Share capital	1,457	934
Share premium reserve	148,763	123,597
Reserves	8,513	4,338
Accumulated deficit	(119,370)	(75,733)
Equity attributable to owners of the Company	39,363	53,136
Non-controlling interests	(38)
Total equity	39,325	53,136
Liabilities
Borrowings	5,284	5,697
Non-current liabilities.	5,284	5,697
Borrowings	1,960
Trade payables	546	328
Social security and other taxes	1,019	312
Pension premiums		13
Deferred income	347
Other current liabilities	4,622	6,057
Current liabilities	8,494	6,710
Total liabilities	13,778	12,407
Total equity and liabilities	€ 53,103	€ 65,543

Consolidated Statement of Profit or Loss and Comprehensive Income - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statement of Profit or Loss and Comprehensive Income
Other income	€ 1,495	€ 1,828	€ 3,235
Research and development costs	(31,153)	(31,923)	(23,401)
General and administrative costs	(10,840)	(9,478)	(6,837)
Total operating costs	(41,993)	(41,401)	(30,238)
Operating result	(40,498)	(39,573)	(27,003)
Financial income and expense	(3,175)	470	6,171
Result before corporate income taxes	(43,673)	(39,103)	(20,832)
Corporate income taxes	(2)
Result for the year	(43,675)	(39,103)	(20,832)
Net loss (attributable to equity holders of the Company)	(43,637)	(39,103)	(20,832)
Items that are or may be reclassified to profit or loss
Foreign operations – foreign currency translation differences	151	(16)	1
Total comprehensive loss (attributable to equity holders of the Company)	(43,524)	(39,119)	(20,831)
Result attributable to
Owners of the Company	(43,637)	(39,103)	(20,832)
Non-controlling interests	(38)
Profit (loss)	€ (43,675)	€ (39,103)	€ (20,832)
Share information
Weighted average number of shares outstanding	25,374,807	23,346,507	23,343,262
Basic and diluted loss per share	€ (1.72)	€ (1.67)	€ (0.89)

Consolidated Statement of Changes in Equity - EUR (€) € in Thousands	Share capital	Share Premium Reserve	Equity Settled Employee Benefit Reserve	Translation Reserve	Accumulated Deficit	Total	Non-controlling Interests [Member]	Total
Balance at beginning of period at Dec. 31, 2014	€ 934	€ 123,581	€ 687		€ (15,798)	€ 109,404		€ 109,404
Result for the year					(20,832)	(20,832)		(20,832)
Other comprehensive income				€ 1		1		1
Recognition of share-based payments			1,212			1,212		1,212
Shares options exercised		14				14		14
Balance at end of period at Dec. 31, 2015	934	123,595	1,899	1	(36,630)	89,799		89,799
Result for the year					(39,103)	(39,103)		(39,103)
Other comprehensive income				(16)		(16)		(16)
Recognition of share-based payments			2,454			2,454		2,454
Shares options exercised		2				2		2
Balance at end of period at Dec. 31, 2016	934	123,597	4,353	(15)	(75,733)	53,136		53,136
Result for the year					(43,637)	(43,637)	€ (38)	(43,675)
Other comprehensive income				151		151		151
Recognition of share-based payments			4,024			4,024		4,024
Issue of ordinary shares	343	25,342				25,685		25,685
Issue of treasury shares	180	(180)
Shares options exercised		4				4		4
Balance at end of period at Dec. 31, 2017	€ 1,457	€ 148,763	€ 8,377	€ 136	€ (119,370)	€ 39,363	€ (38)	€ 39,325

- Definition

The amount of residual interest in the assets of the entity after deducting all its liabilities.

+ References + Details

- Definition

The total of income less expenses, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

+ References

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+ Details

Consolidated Statement of Cash Flows - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flow from operating activities
Net loss	€ (43,675)	€ (39,103)	€ (20,832)
Adjustments for:
Depreciation	1,065	1,245	480
Share-based payment expenses	4,024	2,454	1,212
Financial income and expense	3,175	(470)	(6,171)
Net foreign exchange gain / (loss)	151	(16)	1
Changes in working capital	164	1,433	637
Corporate income tax paid	(2)
Interest received	147	236	441
Net cash used in operating activities	(34,951)	(34,221)	(24,232)
Cash flow from investing activities
Purchases of intangible assets			(28)
Purchases of property, plant and equipment	(121)	(2,539)	(1,296)
Net cash used in investing activities	(121)	(2,539)	(1,324)
Cash flow from financing activities
Proceeds from issuance of shares, net of transaction costs	25,685
Proceeds from exercise of share options	4	2	14
Proceeds from borrowings	301	370	1,640
Proceeds from convertible loans	650
Redemption of financial lease		(15)	(34)
Net cash generated by financing activities	26,640	357	1,620
Net increase/(decrease) in cash and cash equivalents	(8,432)	(36,403)	(23,936)
Currency effect cash and cash equivalents	(2,669)	738	6,065
Cash and cash equivalents at the beginning of the year	59,200	94,865	112,736
Cash and cash equivalents at the end of the year	€ 48,099	€ 59,200	€ 94,865

General Information

12 Months Ended

Dec. 31, 2017

General Information

General Information

PROQR THERAPEUTICS N.V.

Notes to the Consolidated Financial Statements

1. General Information

ProQR Therapeutics N.V., or “ProQR” or the “Company”, is a development stage company domiciled in the Netherlands that primarily focuses on the development and commercialization of novel therapeutic medicines.

Since September 18, 2014, the Company’s ordinary shares are listed on the NASDAQ Global Market under ticker symbol PRQR.

The Company was incorporated in the Netherlands, on February 21, 2012 and was reorganized from a private company with limited liability to a public company with limited liability on September 23, 2014. The Company has its statutory seat in Leiden, the Netherlands. The address of its headquarters and registered office is Zernikedreef 9, 2333 CK Leiden, the Netherlands.

At December 31, 2017, ProQR Therapeutics N.V. is the ultimate parent company of the following entities:

ProQR Therapeutics Holding B.V. (the Netherlands, 100%);

ProQR Therapeutics I B.V. (the Netherlands, 100%);

ProQR Therapeutics II B.V. (the Netherlands, 100%);

ProQR Therapeutics III B.V. (the Netherlands, 100%);

ProQR Therapeutics IV B.V. (the Netherlands, 100%);

ProQR Therapeutics VI B.V. (the Netherlands, 100%);

ProQR Therapeutics VII B.V. (the Netherlands, 100%);

ProQR Therapeutics VIII B.V. (the Netherlands, 100%);

ProQR Therapeutics IX B.V. (the Netherlands, 100%);

Amylon Therapeutics B.V. (the Netherlands, 80%);

ProQR Therapeutics I Inc. (United States, 100%).

ProQR Therapeutics N.V. is also statutory director of Stichting Bewaarneming Aandelen ProQR (“ESOP Foundation”) and has full control over this entity.

As used in these consolidated financial statements, unless the context indicates otherwise, all references to “ProQR”, the “Company” or the “Group” refer to ProQR Therapeutics N.V. including its subsidiaries and the ESOP Foundation.

Basis of Preparation

12 Months Ended

Dec. 31, 2017

Basis of Preparation

Basis of Preparation

2. Basis of preparation

(a) Statement of compliance

These consolidated financial statements have been prepared in accordance with International Financial Reporting Standards, or IFRS, as issued by the IASB.

(b) Basis of measurement

The financial statements have been prepared on the historical cost basis except for financial instruments and share-based payment obligations which have been based on fair value. Historical cost is generally based on the fair value of the consideration given in exchange for assets.

These consolidated financial statements are presented in euro, which is the Company’s functional currency. All amounts have been rounded to the nearest thousand, unless otherwise indicated.

(d) Going Concern

The management board of ProQR has, upon preparing and finalizing the 2017 financial statements, assessed the Company’s ability to fund its operations for a period of at least one year after the date of signing these financial statements.

The management board of the Company is confident about the continuity of the Company based on its existing funding, taking into account the Company’s current cash position and the projected cash flows based on the activities under execution on the basis of ProQR’s business plan and budget.

(e) Use of estimates and judgements

In preparing these consolidated financial statements, management has made judgements, estimates and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, income and expenses. Actual results may differ from these estimates.

Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimate is revised if the revision affects only that period or in the period of the revision and future periods if the revision affects both current and future periods.

Information about assumptions and estimation uncertainties that may have a significant risk of resulting in a material adjustment is included below.

(i) Share-based payments

Share options granted to employees and consultants are measured at the fair value of the equity instruments granted. Fair value is determined through the use of an option-pricing model considering, among others, the following variables:

the exercise price of the option;

the expected life of the option;

the current value of the underlying shares;

the expected volatility of the share price;

the dividends expected on the shares; and

the risk-free interest rate for the life of the option.

For the Company’s share option plans, management’s judgment is that the Black-Scholes valuation method is the most appropriate for determining the fair value of the Company’s share options.

Initially, the Company’s ordinary shares were not publicly traded and consequently the Company needed to estimate the fair value of its share and the expected volatility of that value. The expected volatility of all options granted was therefore based on the average historical volatility of the Company’s peers over a period that agrees with the expected option life. All assumptions and estimates are further discussed in Note 12(d) to the financial statements. The value of the underlying shares was determined on the basis of the prior sale of company stock method. As such, the Company has benchmarked the value per share to external transactions of Company shares and external financing rounds.

For options granted from the moment of listing as stated above, the Company uses the closing price of the ordinary shares on the previous business day as exercise price of the options granted.

The result of the share option valuations and the related compensation expense is dependent on the model and input parameters used. Even though Management considers the fair values reasonable and defensible based on the methodologies applied and the information available, others might derive a different fair value for the Company’s share options.

(ii) Corporate income taxes

The Company recognizes deferred tax assets arising from unused tax losses or tax credits only to the extent that the Company has sufficient taxable temporary differences or there is convincing evidence that sufficient taxable profit will be available against which the unused tax losses or unused tax credits can be utilized. Management’s judgment is that such convincing evidence is currently not sufficiently available and a deferred tax asset is therefore only recognized to the extent that the Company has sufficient taxable temporary differences.

(iii) Grant income

Grant income is not recognized until there is reasonable assurance that the Company will comply with the conditions attached to them. Grants are recognized in profit or loss on a systematic basis over the period the Company recognizes as expenses the related costs for which the grants are expected to compensate.

(iv) Research and development expenditures

Research expenditures are currently not capitalized but are reflected in the income statement because the criteria for capitalization are not met. At each balance sheet date, the Company estimates the level of service performed by the vendors and the associated costs incurred for the services performed.

Although we do not expect the estimates to be materially different from amounts actually incurred, the understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in reporting amounts that are too high or too low in any particular period.

(f) Changes in accounting policies

The financial statements have been prepared on the basis of International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (“IASB”). New Standards and Interpretations, which became effective as of January 1, 2017, did not have a material impact on our financial statements.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Significant Accounting Policies

Significant Accounting Policies

3. Significant Accounting Policies

The Company has consistently applied the following accounting policies to all periods presented in these consolidated financial statements.

(a) Basis of consolidation

(i) Subsidiaries

Subsidiaries are entities controlled by the Group. The Group controls an entity when it has power over the entity, is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. The Group reassesses whether or not it controls an entity if facts and circumstances indicate that there are changes to one or more of these elements. The financial statements of subsidiaries are included in the consolidated financial statements from the date on which control commences until the date on which control ceases.

(ii) Non-controlling interests (“NCI”)

NCI are measured at their proportionate share of the acquiree's identifiable net assets at the acquisition date. Changes in the Group's interest in a subsidiary that do not result in a loss of control are accounted for as equity transactions.

(iii) Loss of control

When the Group loses control over a subsidiary, it derecognises the assets and liabilities of the subsidiary, and any non-controlling interests and other components of equity. Any resulting gain or loss is recognised in profit or loss. Any interest retained in the former subsidiary is measured at fair value when control is lost.

(iv) Transactions eliminated on consolidation

Intra-group balances and transactions, and any unrealised income and expenses arising from intra-group transactions, are eliminated. Unrealised gains arising from transactions with equity-accounted investees are eliminated against the investment to the extent of the Group’s interest in the investee. Unrealised losses are eliminated in the same way as unrealised gains, but only to the extent that there is no evidence of impairment.

(b) Classes of financial instruments

Financial instruments are both primary financial instruments, such as receivables and payables, and financial derivatives. For primary financial instruments, reference is made to the treatment per the corresponding balance sheet item.

Financial derivatives are valued at fair value. Upon first recognition, financial derivatives are recognized at fair value and then revalued as at balance sheet date.

(i) Foreign currency transactions

Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions.

Monetary assets and liabilities denominated in foreign currencies are translated into the functional currency at the exchange rate at the reporting date. Non-monetary assets and liabilities denominated in foreign currencies that are measured at fair value are translated into the functional currency at the exchange rate when the fair value was determined. Foreign currency differences are generally recognized in profit or loss. Non-monetary items that are measured based on historical cost in a foreign currency are not translated.

(ii) Foreign operations

The assets and liabilities of foreign operations are translated into euro at exchange rates at the reporting date. The income and expenses of foreign operations are translated into euros at the exchange rates at the dates of the transactions. Foreign currency differences are recognized in OCI and accumulated in the translation reserve, except to the extent that the translation difference is allocated to NCI.

(d) Recognition of other income

Other income includes amounts earned from third parties and are recognized when earned in accordance with the substance and under the terms of the related agreements and when it is probable that the economic benefits associated with the transaction will flow to the entity and the amount of the income can be measured reliably. The grants are recognized in other income on a systematic basis over the period the Company recognizes as expenses the related costs for which the grants are expected to compensate.

(e) Government grants — WBSO

The WBSO (“afdrachtvermindering speur- en ontwikkelingswerk”) is a Dutch fiscal facility that provides subsidies to companies, knowledge centers and self-employed people who perform research and development activities (as defined in the WBSO Act). Under this Act, a contribution is paid towards the labor costs of employees directly involved in research and development. The contribution is in the form of a reduction of payroll taxes and social security contributions recognized on a net basis within the labor costs. Subsidies relating to labor costs are deferred and recognized in the income statement in the period necessary to match them with the labor costs that they are intended to compensate.

(f) Employee benefits

(i) Short-term employee benefits

Short-term employee benefits are expensed as the related service is provided. A liability is recognized for the amount expected to be paid if the Group has a present legal or constructive obligation to pay this amount as a result of past service provided by the employee and the obligation can be estimated reliably.

(ii) Share-based payment transactions

The grant-date fair value of equity-settled share-based payment awards granted to employees is generally recognized as an expense, with a corresponding increase in equity, over the vesting period of the awards. The amount recognized as an expense is adjusted to reflect the number of awards for which the related service conditions are expected to be met, such that the amount ultimately recognized is based on the number of awards that meet the related service and non-market performance conditions at the vesting date. For share-based payment awards with non-vesting conditions, the grant-date fair value of the share-based payment is measured to reflect such conditions and there is no true-up for differences between expected and actual outcomes.

(iii) Pension obligations

The Company operates defined contribution pension plans for all employees funded through payments to insurance companies. The Company has no legal or constructive obligation to pay further contributions once the contributions have been paid. The contributions are recognized as employee benefit expense when employees have rendered the service entitling them to the contributions. Prepaid contributions are recognized as an asset to the extent that a cash refund or a reduction in the future payments is available.

(g) Taxation

Income tax expense represents the sum of the tax currently payable and deferred tax. It is recognized in profit or loss except to the extent that it relates to a business combination, or items recognized directly in equity or in OCI.

(i) Current tax

The tax currently payable is based on taxable profit for the year. Taxable profit differs from profit as reported in the income statement because of items of income or expense that are taxable or deductible in other years and items that are never taxable or deductible. The Company’s liability for current tax is calculated using tax rates that have been enacted or substantively enacted by the end of the reporting period.

(ii) Deferred tax

Deferred tax is recognized on differences between the carrying amounts of assets and liabilities in the financial statements and the corresponding tax bases used in the computation of taxable profit.

The carrying amount of deferred tax assets is reviewed at the end of each reporting period and reduced to the extent that it is no longer probable that sufficient taxable profits will be available to allow all or part of the asset to be recovered. Since the Company does not expect to be profitable in the foreseeable future, its deferred tax assets are valued at nil.

Deferred tax assets and liabilities are measured at the tax rates that are expected to apply in the period in which the liability is settled or the asset realized, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period. The measurement of deferred tax liabilities and assets reflects the tax consequences that would follow from the manner in which the Company expects, at the end of the reporting period, to recover or settle the carrying amount of its assets and liabilities.

(h) Intangible assets

(i) Licenses

Acquired patents have a finite useful life and are carried at cost less accumulated amortization and impairment losses. Amortization is calculated using the straight-line method to allocate the cost of patents over their estimated useful lives (generally 10 years unless a patent expires prior to that date). Amortization begins when an asset is available for its intended use.

(ii) Research and development

Research expenditures are recognized as expenses as incurred. Costs incurred on development projects are recognized as intangible assets as of the date that it can be established that it is probable that future economic benefits that are attributable to the asset will flow to the Company considering its commercial and technological feasibility, generally when filed for regulatory approval for commercial production, and when costs can be measured reliably. Given the current stage of the development of the Company’s products no development expenditures have yet been capitalized.

Registration costs for patents are part of the expenditures for the research and development project. Therefore, registration costs for patents are expensed as incurred as long as the research and development project concerned does not yet meet the criteria for capitalization.

(iii) Other intangible assets

Other intangible assets, including software, that are acquired by the Company and have finite useful lives are measured at cost less accumulated amortization and accumulated impairment losses.

(iv) Amortization

Amortization is calculated to write off the cost of intangible assets less their estimated residual values using the straight-line method over their estimated useful lives, and is recognized in profit or loss.

The estimated useful lives for current and comparative periods are as follows:


 software:		3	years;

Amortization methods, useful lives and residual values are reviewed at each reporting date and adjusted if appropriate.

(i) Property, plant and equipment

(i) Recognition and measurement

Items of property, plant and equipment are measured at cost less accumulated depreciation and any accumulated impairment losses. If significant parts of an item of property, plant and equipment have different useful lives, then they are accounted for as separate items (major components) of property, plant and equipment. Any gain or loss on disposal of an item of property, plant and equipment is recognized in profit or loss.

(ii) Depreciation

Depreciation is calculated to write off the cost of items of property, plant and equipment less their estimated residual values using the straight-line method over their estimated useful lives, and is recognized in profit or loss. Leased assets are depreciated over the shorter of the lease term and their useful lives unless it is reasonably certain that the Company will obtain ownership by the end of the lease term.

The estimated useful lives of property, plant and equipment for current and comparative periods are as follows:


 leasehold improvements:	5-10	years;
 laboratory equipment:	5	years;
 other:	3-5	years.

Depreciation methods, useful lives and residual values are reviewed at each reporting date and adjusted if appropriate.

(j) Impairment of tangible and intangible assets

At the end of each reporting period, the Company reviews the carrying amounts of its tangible and intangible assets to determine whether there is any indication that those assets have suffered an impairment loss. If any such indication exists, the recoverable amount of the asset is estimated in order to determine the extent of the impairment loss (if any). Where it is not possible to estimate the recoverable amount of an individual asset, the Company estimates the recoverable amount of the cash-generating unit to which the asset belongs. Where a reasonable and consistent basis of allocation can be identified, corporate assets are also allocated to individual cash-generating units, or otherwise they are allocated to the smallest group of cash-generating units for which a reasonable and consistent allocation basis can be identified.

Intangible assets with indefinite useful lives and intangible assets not yet available for use are tested for impairment at least annually, and whenever there is an indication that the asset may be impaired.

The recoverable amount is the higher of fair value less costs of disposal and value in use. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset for which the estimates of future cash flows have not been adjusted.

If the recoverable amount of an asset (or cash-generating unit) is estimated to be less than its carrying amount, the carrying amount of the asset (or cash-generating unit) is reduced to its recoverable amount. An impairment loss is recognized immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the impairment loss is treated as a revaluation decrease.

Where an impairment loss subsequently reverses, the carrying amount of the asset (or cash-generating unit) is increased to the revised estimate of its recoverable amount, but so that the increased carrying amount does not exceed the carrying amount that would have been determined had no impairment loss been recognized for the asset (or cash-generating unit) in prior years. A reversal of an impairment loss is recognized immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the reversal of the impairment loss is treated as a revaluation increase.

(k) Financial assets

All financial assets are recognized and derecognized on the trade date where the purchase or sale of a financial asset is under a contract whose terms require delivery of the financial asset within the timeframe established by the market concerned, and are initially measured at fair value, plus transaction costs, except for those financial assets classified as at fair value through profit or loss, which are initially measured at fair value.

Loans and receivables

Trade receivables, loans and other receivables that have fixed or determinable payments that are not quoted in an active market are classified as “loans and receivables”. Loans and receivables are measured at amortized cost using the effective interest method, less any impairment.

An allowance for doubtful accounts is established when there is objective evidence that the Company will not be able to collect all amounts due according to the original terms of receivables. Significant financial difficulties of the debtor, probability that the debtor will enter into bankruptcy or financial reorganization, and default or delinquency in payments are considered indicators that the trade receivable is impaired. Loans and receivables are included in ‘current assets’, except for maturities greater than 12 months after the balance sheet date, which are classified as ‘non-current assets’.

For all financial assets, the fair value approximates its carrying value.

(l) Cash and cash equivalents

Cash and cash equivalents include cash on hand and all highly liquid investments with original maturities of three months or less that are convertible to a known amount of cash and bear an insignificant risk of change in value.

(m) Financial liabilities and equity instruments

Debt and equity instruments are classified as either financial liabilities or as equity in accordance with the substance of the contractual arrangement.

Equity instruments

An equity instrument is any contract that evidences a residual interest in the assets of an entity after deducting all of its liabilities. Equity instruments issued by the Company are recognized at the proceeds received, net of direct issue costs.

Compound financial instruments

Compound financial instruments issued by the Group comprise convertible notes denominated in euro that can be converted to share capital at the option of the holder, when the number of shares to be issued is fixed and does not vary with changes in fair value.

The liability component of a compound financial instrument is recognised initially at the fair value of a similar liability that does not have an equity conversion option. The equity component is recognised initially at the difference between the fair value of the compound financial instrument as a whole and the fair value of the liability component. Any directly attributable transaction costs are allocated to the liability and equity components in proportion to their initial carrying amounts.

Subsequent to initial recognition, the liability component of a compound financial instrument is measured at amortised cost using the effective interest method. The equity component of a compound financial instrument is not remeasured.

Interest related to the financial liability is recognised in profit or loss. On conversion, the financial liability is reclassified to equity and no gain or loss is recognised.

Other financial liabilities

Other financial liabilities, including borrowings, are initially measured at fair value, net of transaction costs incurred, and are subsequently measured at amortized cost using the effective interest method, with interest expense recognized on an effective yield basis.

The effective interest method is a method of calculating the amortized cost of a financial liability and of allocating interest expense over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash payments through the expected life of the financial liability, or, where appropriate, a shorter period.

Borrowings and other financial liabilities are classified as ‘non-current liabilities,’ other than liabilities with maturities up to one year, which are classified as “current liabilities”.

The Company derecognizes financial liabilities when the liability is discharged, cancelled or expired. For all financial liabilities, the fair value approximates its carrying amount.

(n) Leases

(i) Determining whether an arrangement contains a lease

At inception of an arrangement, the Company determines whether such an arrangement is or contains a lease.

At inception or on reassessment of an arrangement that contains a lease, the Company separates payments and other consideration required by such an arrangement into those for the lease and those for other elements on the basis of their relative fair values. If the Company concludes for a finance lease that it is impracticable to separate the payments reliably, then an asset and a liability are recognized at an amount equal to the fair value of the underlying asset. Subsequently, the liability is reduced as payments are made and an imputed finance cost on the liability is recognized using the Company’s incremental borrowing rate.

(ii) Leased assets

Assets held by the Company under leases that transfer to the Company substantially all of the risks and rewards of ownership are classified as finance leases. The leased assets are measured initially at an amount equal to the lower of their fair value and the present value of the minimum lease payments. Subsequent to initial recognition, the assets are accounted for in accordance with the accounting policy applicable to that asset.

Assets held under other leases are classified as operating leases and are not recognized in the Company’s statement of financial position.

(iii) Lease payments

Payments made under operating leases are recognized in profit or loss on a straight-line basis over the term of the lease. Lease incentives received are recognized as an integral part of the total lease expense, over the term of the lease.

Minimum lease payments made under finance leases are apportioned between the finance expense and the reduction of the outstanding liability. The finance expense is allocated to each period during the lease term so as to produce a constant periodic rate of interest on the remaining balance of the liability.

New Standards and Interpretations not yet Adopted	12 Months Ended
New Standards and Interpretations not yet Adopted	Dec. 31, 2017
New Standards and Interpretations not yet Adopted
New Standards and Interpretations not yet Adopted	4. New standards and interpretations not yet adopted A number of new standards, amendments to standards and interpretations are effective for annual periods beginning after January 1, 2018, and have not been applied in preparing these consolidated financial statements. Those which may be relevant to the Group are set out below. The Group does not plan to adopt these standards early. IFRS 9 Financial Instruments IFRS 9, published in July 2014, replaces the existing guidance in IAS 39 Financial Instruments: Recognition and Measurement. IFRS 9 includes revised guidance on the classification and measurement of financial instruments, including a new expected credit loss model for calculating impairment on financial assets, and the new general hedge accounting requirements. It also carries forward the guidance on recognition and derecognition of financial instruments from IAS 39. IFRS 9 is effective for annual reporting periods beginning on or after January 1, 2018, with early adoption permitted. IFRS 15 Revenue from Contracts with Customers IFRS 15 establishes a comprehensive framework for determining whether, how much and when revenue is recognised. It replaces existing revenue recognition guidance, including IAS 18 Revenue, IAS 11 Construction Contracts and IFRIC 13 Customer Loyalty Programmes. IFRS 15 is effective for annual reporting periods beginning on or after January 1, 2018, with early adoption permitted. IFRS 16 Leases IFRS 16 specifies how a company will recognise, measure, present and disclose leases. The standard provides a single lessee accounting model, requiring lessees to recognise assets and liabilities for all leases unless the lease term is 12 months or less or the underlying asset has a low value. Lessors continue to classify leases as operating or finance, with IFRS 16’s approach to lessor accounting substantially unchanged from its predecessor, IAS 17. IFRS 16 is effective for annual reporting periods beginning on or after January 1, 2019, with early adoption permitted and is expected to have an effect on our balance sheet of approximately € 5 million. The adoption of these Standards and Interpretations are not expected to have a material effect on the financial statements.

Financial Risk Management

12 Months Ended

Dec. 31, 2017

Financial Risk Management

Financial Risk Management

5. Financial Risk Management

5.1 Financial risk factors

The Company’s activities expose it to a variety of financial risks: market risk (including currency risk, interest rate risk and price risk), credit risk and liquidity risk. The Company’s overall financial risk management seeks to minimize potential adverse effects resulting from unpredictability of financial markets on the Company’s financial performance.

Risk management is carried out by the finance department. The finance department identifies and evaluates financial risks and proposes mitigating actions if deemed appropriate.

(a) Market risk

Market risk is the risk that changes in market prices – such as foreign exchange rates, interest rates and equity prices – will affect the Company’s income or the value of its holdings of financial instruments. The objective of market risk management is to manage and control market risk exposures within acceptable parameters, while optimizing the return.

Foreign exchange risk

Foreign exchange risk arises from future commercial transactions and recognized assets and liabilities in foreign currencies, primarily with respect to the U.S. Dollar. The Company has an exposure associated with the time delay between entering into a contract, budget or forecast and the realization thereof. The Company operates a foreign exchange policy to manage the foreign exchange risk against the functional currency based on the Company’s cash balances and the projected future spend per major currency.

At December 31, 2017 there was a net liability in U.S. Dollars of € 0.7 million (2016: € 2.4 million). Foreign currency denominated receivables and trade payables are short term in nature (generally 30 to 45 days). As a result foreign exchange rate movements on receivables and trade payables, during the years presented had an immaterial effect on the financial statements.

At year-end, a substantial amount of our cash balances are denominated in U.S. Dollars. This amount reflects our current expectation of future expenditure in U.S. dollars.

A reasonably possible weakening of the U.S. Dollar by 10% against all other currencies at December 31, 2017 would have affected the measurement of our cash balances denominated in a U.S. Dollar and affected equity and profit or loss by € 2.5 million (2016: € 2.5 million). The analysis assumes that all other variables, in particular interest rates, remain constant.

Price risk

The market prices for the production of preclinical and clinical materials and services as well as external contracted research may vary over time. Currently, the commercial prices of any of the Company’s product candidates is uncertain. When the development products near the regulatory approval date or potential regulatory approval date, the uncertainty of the potential sales price decreases. The Company is not exposed to commodity price risk.

Furthermore the Company does not hold investments classified as available-for-sale or at fair value through profit or loss, therefore are not exposed to equity securities price risk.

Cash flow and fair value Interest rate risk

The Company’s exposure to interest rate risks is limited due to the use of loans with fixed rates. The Company has several loans with fixed interest rates, totaling €7,244,000 at December 31, 2017 (2016: € 5,697,000). Details on the interest rates and maturities of these loans are provided in Note 13.

(b) Credit risk

Credit risk represents the risk of financial loss caused by default of the counterparty. The Company has no large receivables balances with external parties. The Company’s principal financial assets are cash and cash equivalents which are held at ABN Amro, Rabobank and Wells Fargo. Our cash management policy is focused on preserving capital, providing liquidity for operations and optimizing yield while accepting limited risk (Short-term credit ratings must be rated A‑1/P‑1/F1 at a minimum by at least one of the Nationally Recognized Statistical Rating Organizations (NRSROs) specifically Moody’s, Standard & Poor’s or Fitch. Long-term credit rating must be rated A2 or A at a minimum by at least one NRSRO).

At December 31, 2017 and December 31, 2016, substantially all of our cash and cash equivalents were held at three large institutions, Rabobank, ABN Amro and Wells Fargo. All institutions are highly rated (ratings of Aa2, A1 and A2 for Rabobank, ABN Amro and Wells Fargo respectively) with sufficient capital adequacy and liquidity metrics.

There are no financial assets past due date or impaired. No credit limits were exceeded during the reporting period.

Liquidity risk represents the risk that an entity will encounter difficulty in meeting obligations associated with its financial liabilities. Prudent liquidity risk management implies ensuring sufficient availability of cash resources for funding of operations and planning to raise cash if and when needed, either through issue of shares or through credit facilities. Management monitors rolling forecasts of the Company’s liquidity reserve on the basis of expected cash flow.

The table below analyzes ProQR’s undiscounted liabilities into relevant maturity groupings based on the remaining period at year-end until the contractual maturity date:


	Less than	Between 1	Between 2
	1 year	and 2 years	and 5 years	Over 5 years
	(€ in thousands)
At December 31, 2017
Borrowings	1,960	980	5,981	—
Trade payables and other payables	6,534	—	—	—
Total	8,494	980	5,981	—

At December 31, 2016
Borrowings	—	1,839	4,860	—
Trade payables and other payables	6,710	—	—	—
Total	6,710	1,839	4,860	—

5.2 Capital risk management

The Company’s objectives when managing capital are to safeguard the Company’s ability to continue as a going concern in order to provide returns for shareholders, benefits for other stakeholders and to maintain an optimal capital structure to reduce the cost of capital.

In order to maintain or adjust the capital structure, the Company may adjust the amount of dividends paid to shareholders (although at this time the Company does not have retained earnings and is therefore currently unable to pay dividends), return capital to shareholders, issue new shares or sell assets to reduce debt.

The total amount of equity as recorded on the balance sheet is managed as capital by the Company.

5.3 Fair value measurement

For financial instruments that are measured on the balance sheet at fair value, IFRS 13 requires disclosure of fair value measurements by level of the following fair value measurement hierarchy:

quoted prices (unadjusted) in active markets for identical assets or liabilities (level 1);

inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly (that is, as prices) or indirectly (that is, derived from prices) (level 2); and

inputs for the asset or liability that are not based on observable market data (that is, unobservable inputs) (level 3).

The carrying amount of all financial assets and financial liabilities is a reasonable approximation of the fair value and therefore information about the fair values of each class has not been disclosed.

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2017
Segment Information
Segment Information	6. Segment Information The Company operates in one reportable segment, which comprises the discovery and development of innovative, RNA based therapeutics. The management board is identified as the chief operating decision maker. The management board reviews the operating results regularly to make decisions about resources and to assess overall performance. The Company has not generated any sales revenues since inception. All non-current assets of the Company are located in the Netherlands. The amounts provided to the management board with respect to total assets and liabilities are measured in a manner consistent with that of the financial statements.

Intangible Assets

12 Months Ended

Dec. 31, 2017

Intangible Assets

Intangible Assets

7. Intangible Assets


	Licenses	Software	Total
	(€ in thousands)	(€ in thousands)	(€ in thousands)
Balance at January 1, 2016
Cost	39	152	191
Accumulated amortization	—	(50)	(50)
Carrying amount	39	102	141

Additions	—	—	—
Amortization	—	(51)	(51)
Movement for the period	—	(51)	(51)

Balance at December 31, 2016
Cost	39	152	191
Accumulated amortization	—	(101)	(101)
Carrying amount	39	51	90

Additions	—	—	—
Amortization	—	(51)	(51)
Movement for the period	—	(51)	(51)

Balance at December 31, 2017
Cost	39	152	191
Accumulated amortization	—	(152)	(152)
Carrying amount	39	—	39

In 2012, the Company acquired an exclusive license from the Massachusetts General Hospital. The initial payment in respect of the license, in the amount of € 39,000, will be amortized over the commercial life of products based on the license during the patent-life.

The amortization charge for 2017 is included in the general and administrative costs for an amount of €51,000 (2016: € 51,000).

Property, Plant and Equipment ('PP&E')

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment ('PP&E")

Property, Plant and Equipment ('PP&E')

8. Property, Plant and Equipment (‘PP&E’)


	Leasehold	Laboratory
	improvements	equipment	Other	Total
	(€ in thousands)	(€ in thousands)	(€ in thousands)	(€ in thousands)
Balance at January 1, 2016
Cost	985	1,136	651	2,772
Accumulated depreciation	(94)	(305)	(174)	(573)
Carrying amount	891	831	477	2,199

Additions	1,166	806	461	2,433
Depreciation	(499)	(340)	(332)	(1,171)
Transfer	(196)	—	196
Disposals	(23)	—	—	(23)
Movement for the period	448	466	325	1,239

Balance at December 31, 2016
Cost	1,847	1,957	1,283	5,087
Accumulated depreciation	(508)	(660)	(481)	(1,649)
Carrying amount	1,339	1,297	802	3,438

Additions	9	47	26	82
Depreciation	(294)	(409)	(312)	(1,015)
Disposals	—	—	—	—
Movement for the period	(285)	(362)	(286)	(933)

Balance at December 31, 2017
Cost	1,856	2,004	1,309	5,169
Accumulated depreciation	(802)	(1,069)	(793)	(2,664)
Carrying amount	1,054	935	516	2,505

The depreciation charge for 2017 is included in the research and development costs for an amount of € 836,000 (2016: € 907,000) and in the general and administrative costs for an amount of € 179,000 (2016: € 264,000).

Social Security and Other Taxes

12 Months Ended

Dec. 31, 2017

Social Security and Other Taxes

Social Security and Other Taxes

9. Social Security and Other Taxes


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Value added tax	396	395
Wage tax	—	—
	396	395

All receivables are considered short-term and due within one year.

Prepayments and Other Receivables

12 Months Ended

Dec. 31, 2017

Prepayments And Other Receivables.

Prepayments and Other Receivables

10. Prepayments and Other Receivables


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Prepayments	1,991	1,250
Other receivables	73	1,170
	2,064	2,420

All receivables are considered short-term and due within one year.

Cash and Cash Equivalents

12 Months Ended

Dec. 31, 2017

Cash and Cash Equivalents.

Cash and Cash Equivalents

11. Cash and Cash Equivalents


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Cash at banks	48,099	56,354
Bank deposits	—	2,846
	48,099	59,200

The cash at banks is at full disposal of the Company. Bank deposits are convertible into cash upon request of the Company.

Shareholders’ Equity

12 Months Ended

Dec. 31, 2017

Shareholders’ Equity

Shareholders’ Equity

12. Shareholders’ Equity

(a) Share capital


	Number of shares 2017	Number of shares 2016	Number of shares 2015
	Ordinary	Ordinary	Ordinary
Balance at January 1	23,346,856	23,345,965	23,338,154
Issued for cash	8,573,975	—	—
Exercise of share options	1,034	891	7,811
Treasury shares issued	4,503,149	—	—
Balance at December 31	36,425,014	23,346,856	23,345,965

The authorized share capital of the Company amounting to € 3,000,000 consists of 37,500,000 ordinary shares and 37,500,000 preference shares with a par value of € 0.04 per share. At December 31, 2017, 36,425,014 ordinary shares were issued and fully paid in cash, of which 4,503,149 were held by the Company as treasury shares (2016: 1,173,958).

On October 2, 2015, the Company filed a shelf registration statement, which permitted: (a) the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $ 200,000,000 (€ 166,764,000) of its ordinary shares, warrants and/or units; and (b) as part of the $ 200,000,000, the offering, issuance and sale by us of up to a maximum aggregate offering price of $ 60,000,000 (€ 50,029,000) of its ordinary shares that may be issued and sold under a sales agreement in one or more at-the-market offerings. In 2017, the Company has issued 976,477 shares pursuant to its current at-the-market offering program, resulting in proceeds of € 4,138,000, net of € 127,000 of offering expenses.

On June 28, 2017, the Company agreed to the issuance of 1,200,000 ordinary shares to institutional investors at an issue price of $ 5.00 (€ 4.40) per share in a registered direct offering with gross proceeds of € 5,278,000. The closing of the offering was effected on July 3, 2017. Transaction costs amounted to € 414,000, resulting in net proceeds of € 4,864,000.

In November 2017, the Company consummated an underwritten public offering and concurrent registered direct offering of 6,397,498 ordinary shares at an issue price of $ 3.25 (€ 2.76) per share. The gross proceeds from both offerings amounted to € 17,671,000 while the transaction costs amounted to € 988,000, resulting in net proceeds of € 16,683,000.

(b) Equity settled employee benefit reserve

The costs of share options for employees, members of the supervisory board and members of the management board are recognized in the income statement, together with a corresponding increase in equity during the vesting period, taking into account (deferral of) corporate income taxes. The accumulated expense of share options recognized in the income statement is shown separately in the equity category ‘equity settled employee benefit reserve’ in the ‘statement of changes in equity’. On September 25, 2017, we established a Dutch foundation named Stichting Bewaarneming Aandelen ProQR for holding shares in trust for employees, members of the Management Board and members of the Supervisory Board of the Company and its group companies who from time to time will exercise options under the Company’s equity incentive plans.

The translation reserve comprises all foreign currency differences arising from the translation of the financial statements of foreign operations.

(d) Share options

The Company operates an equity-settled share-based compensation plan which was introduced in 2013. Options may be granted to employees, members of the supervisory board, members of the management board and consultants. The compensation expenses included in operating costs for this plan were € 4,024,000 in 2017 (2016: € 2,454,000, 2015: € 1,212,000), of which € 2,059,000 (2016: € 1,480,000, 2015: € 801,000) was recorded in general and administrative costs and € 1,965,000 (2016: € 974,000, 2015: € 411,000) was recorded in research and development costs based on employee allocation.

Options granted under this stock option plan are exercisable once vested. Any vesting schedule may be attached to the granted options, however the typical vesting period is four years (25% after every year). The options expire ten years after date of grant. Options granted under the stock option plan are granted at exercise prices which equal the fair value of the ordinary shares of the Company at the date of the grant.

The Company accounts for its employee stock options under the fair value method. The fair value of the options is estimated at the date of grant using the Black-Scholes option-pricing model, with on average the following assumptions:


	Options granted		Options granted		Options granted
	in 2017		in 2016		in 2015
Risk-free interest rate	1.913	%	1.467	%	1.497	%
Expected dividend yield	—	%	—	%	—	%
Expected volatility	88.7	%	86.3	%	86.8	%
Expected life in years	5	years	5	years	5	years

The resulting weighted average grant date fair value of the options amounted to € 3.21 in 2017 (2016: € 3.72, 2015: € 10.35). The stock options granted have a 10 year life following the grant date and are assumed to be exercised five years from date of grant for all awards.

Movements in the number of options outstanding and their related weighted average exercise prices are as follows:


	2017			2016			2015
	Number of	Average		Number of	Average		Number of	Average
	options	exercise price		options	exercise price		options	exercise price
Balance at January 1	2,205,989	€	4.88	1,108,935	€	4.19	998,765	€	2.78
Granted	1,199,447	€	4.63	1,214,126	€	5.49	125,798	€	15.27
Forfeited	(72,527)	€	5.56	(116,181)	€	4.64	(7,817)	€	4.64
Exercised	(1,034)	€	3.54	(891)	€	2.38	(7,811)	€	1.78
Expired	—		—	—		—	—		—
Balance at December 31	3,331,875	€	4.78	2,205,989	€	4.88	1,108,935	€	4.19
Exercisable at December 31	1,148,893			615,246			339,352

The options outstanding at December 31, 2017 had an exercise price in the range of € 1.11 to € 20.34 (2016: € 1.11 to € 20.34, 2015: € 1.11 to € 20.34) and a weighted-average contractual life of 7.9 years (2016: 8.3 years, 2015: 8.3 years).

The weighted-average share price at the date of exercise for share options exercised in 2017 was € 4.32 (2016: € 4.23, 2015: € 19.30).

Please refer to Note 23 for the options granted to key management personnel.

Non-current liabilities

12 Months Ended

Dec. 31, 2017

Non-current liabilities.

Non-current liabilities

13. Non-current liabilities

(a) Borrowings


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Innovation credit	4,899	4,598
Accrued interest on innovation credit	1,683	1,099
Convertible loans	662	—
Total borrowings	7,244	5,697
Current portion	(1,960)	—
	5,284	5,697

Innovation credit (“Innovatiekrediet”)

On June 1, 2012, ProQR was awarded an Innovation credit by the Dutch government, through its agency RVO of the Ministry of Economic Affairs, for the Company’s cystic fibrosis program. Amounts were drawn under this facility in the course of the years 2013 through 2017. The credit covers 35% of the costs incurred in respect of the program up to an initial maximum of € 5.0 million.

The credit is interest-bearing at a rate of 10% per annum. The credit, including accrued interest, is repayable in three installments on November 30, 2018, November 30, 2019 and November 30, 2020, depending on the technical success of the program.

The assets which are co-financed with the granted innovation credit are subject to a right of pledge for the benefit of RVO.

Convertible loans

Convertible loans were issued to Amylon Therapeutics B.V. in 2017 and are interest-bearing at an average rate of 8% per annum. They are convertible into a variable number of ordinary shares within 36 months at the option of the holder or the Company in case financing criteria are met. Any unconverted loans become payable on demand after 24 months in equal quarterly terms.

Current liabilities

12 Months Ended

Dec. 31, 2017

Current Liabilities.

Current Liabilities

14. Current Liabilities


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Borrowings	1,960	—
Trade payables	546	328
Social securities and other taxes	1,019	312
Pension premiums	—	13
Deferred income	347	—
Accrued expenses and other liabilities	4,622	6,057
	8,494	6,710

At December 31, 2017, current liabilities included deferred income resulting from installments received of the € 6 million grant (ProQR: € 4.6 million) from the European Commission (EC) under the Horizon 2020 program to finance the clinical development of eluforsen.

Other income

12 Months Ended

Dec. 31, 2017

Other income.

Other income

15. Other income


	2017	2016	2015
	(€ in thousands)
Grant income	870	1,632	3,188
Rental income from property subleases	625	196	47
	1,495	1,828	3,235

In August 2014, the Company entered into an agreement with Cystic Fibrosis Foundation Therapeutics, Inc., or CFFT, a subsidiary of the Cystic Fibrosis Foundation, pursuant to which CFFT agreed to provide the Company with up to $ 3 million (€ 2.5 million) to support the clinical development of eluforsen. The grant is recognized in other income in the same period in which the related R&D costs are recognized.

In 2015, the European Commission (EC) through its Horizon 2020 program awarded ProQR and its academic partners a grant of € 6 million (ProQR: € 4.6 million) to support the clinical development of eluforsen through December 31, 2017. Horizon 2020 is one of the largest research and innovation programs in the European Union with nearly € 80 billion in available funding for qualified projects from 2014 to 2020.

Both grants are recognized in other income in the same period in which the related R&D costs are recognized.

Employee Benefits

12 Months Ended

Dec. 31, 2017

Employee Benefits

Employee Benefits

17. Employee Benefits


	2017	2016	2015
	(€ in thousands)
Wages and salaries	11,855	10,184	7,128
Social security costs	1,285	1,093	596
Pension costs — defined contribution plans	860	764	478
Equity-settled share based payments	4,024	2,454	1,212
	18,024	14,495	9,414
Average number of employees for the period	139.9	133.4	86.1

Employees per activity at December 31 (converted to FTE):


	December 31, 2017	December 31, 2016	December 31, 2015
Research and Development	96.2	100.4	72.4
General and Administrative	34.0	32.9	27.1
Total number of employees at December 31 (converted to FTE)	130.2	133.3	99.5

Of all employees 125.2 FTE are employed in the Netherlands (2016: 128.3 FTE).

Included in the wages and salaries for 2017 is a credit of € 723,000 (2016: € 807,000, 2015: € 372,000) with respect to WBSO subsidies.

Financial Income and Expense

12 Months Ended

Dec. 31, 2017

Financial Income and Expense

Financial Income and Expense

18. Financial Income and Expense


	2017	2016	2015
	(€ in thousands)
Interest income:
Current accounts and deposits	90	270	501
Interest costs:
Interest on loans and borrowings	(596)	(538)	(395)
Foreign exchange result:
Net foreign exchange benefit/(loss)	(2,669)	738	6,065
	(3,175)	470	6,171

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Taxes

Income Taxes

19. Income Taxes

The calculation of the tax charge is as follows:


	2017		2016		2015
	(€ in thousands)
Income tax based on domestic rate	10,918		9,776		5,208
Tax effect of:
Non-deductible expenses	(634)		(622)		(309)
Tax incentives	—		(46)		136
Current year losses for which no deferred tax asset was recognized	(10,257)		(9,045)		(5,035)
Change in unrecognized deductible temporary differences	(25)		(63)		—
Income tax charge	2		—		—
Effective tax rate	—	%	—	%	—	%

Due to the operating losses incurred since inception the Company has no tax provisions as of the balance sheet date. Furthermore, no significant temporary differences exist between accounting and tax results.

Realization of deferred tax assets is dependent on future earnings, if any, the timing and amount of which are uncertain. Accordingly, the Company has not yet recognized any deferred tax asset related to operating losses. As per December 31, 2017, the Company has a total amount of € 123.9 million (2016: € 82.9 million, 2015: € 46.9 million) tax loss carry-forwards available for offset against future taxable profits. According to current tax regulations the first amount of the tax loss carry-forwards will expire in 2021.

Earnings Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share

Earnings Per Share

20. Earnings Per Share

(a) Basic and diluted earnings per share

Basic earnings per share are calculated by dividing the result attributable to equity holders of the Company by the weighted average number of shares outstanding during the year.


	2017		2016		2015
Result attributable to equity holders of the Company (€ in thousands)		(43,637)		(39,103)		(20,832)
Weighted average number of shares outstanding		25,374,807		23,346,507		23,343,262
Basic (and diluted) earnings per share (€ per share)	€	(1.72)	€	(1.67)	€	(0.89)

(b) Diluted earnings per share

For the periods included in these financial statements, the share options are not included in the diluted earnings per share calculation as the Company was loss-making in all periods. Due to the anti-dilutive nature of the outstanding options, basic and diluted earnings per share are equal.

The Company did not declare dividends for any of the years presented in these financial statements.

Operational Leases

12 Months Ended

Dec. 31, 2017

Operational Leases

Operational Leases

21. Operational Leases

Since 2012, the Company is domiciled in Leiden, the Netherlands where it currently has entered into rental agreements for laboratory space and offices.

The lease expenditure charged to the income statement in 2017 amounts to € 2,103,000 (2016: € 1,849,000, 2015: € 703,000). The future aggregate minimum lease payments under non-cancellable operating leases are as follows:


	December 31, 2017	December 31, 2016	December 31, 2015
	(€ in thousands)
Less than 1 year	1,607	1,775	1,938
Between 1 and 5 years	3,312	5,508	7,212
More than 5 years	—	—	—
Total	4,919	7,283	9,150

The Company leased out a part of its offices in the U.S. and the Netherlands. In 2017, total sublease income amounted to € 625,000 (2016: € 196,000, 2015: €47,000), which is recorded in other income. At 31 December, the future minimum lease payments under non-cancellable leases are receivable as follows:


	December 31, 2017	December 31, 2016	December 31, 2015
	(€ in thousands)
Less than 1 year	174	463	185
Between 1 and 5 years	—	—	—
More than 5 years	—	—	—
Total	174	463	185

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2017
Commitments and Contingencies
Commitments and Contingencies	22. Commitments and Contingencies (a) Claims There are no claims known to management related to the activities of the Company. (b) Patent license agreements The Company and the General Hospital Corporation (MGH) have entered into a Patent License Agreement pursuant to which the Company may have certain royalty obligations. The Company is also obligated to pay MGH up to $ 700,000 (€ 584,000) in milestone payments upon the achievement of certain development and regulatory milestones and, beginning after its first commercial sale of a product covered by the licensed patent rights, a $ 10,000 (€ 8,000) annual license fee which is creditable against royalties due to MGH in the same calendar year. In addition, the Company is obligated to pay MGH 2% of any net sales by the Company, its affiliates or sublicensees on licensed products made or sold in the United States, as well as a low double-digit percentage of any payments the Company may receive from any sublicensee anywhere in the world. The Company has entered into various other Patent License Agreements, including those with Radboud University Medical Center, Leiden University Medical Centre, Inserm Transfert and Assistance-Publique-Hôpiteaux de Paris, and PARI Pharma GmbH, under which the Company is granted world-wide exclusive licenses pursuant to which the Company may have certain royalty obligations in relation to its product candidates. Pursuant to the terms of these agreements, the Company has made upfront payments, is obligated to make milestone payments and has to make sales-based royalty payments after market authorization. In specific cases, the Company has the option to make a one-time payment to buy of royalty obligations or in case the Company terminates an agreement before or after regulatory approval of the product. The Company may terminate an agreement for any reason. (c) Clinical support agreements In August 2014, the Company entered into an agreement with Cystic Fibrosis Foundation Therapeutics, Inc., or CFFT, a subsidiary of the Cystic Fibrosis Foundation, pursuant to which CFFT agreed to provide the Company with up to $ 3 million (€ 2.5 million) to support the clinical development of eluforsen. Pursuant to the terms of the agreement, the Company is obligated to make a one-time milestone payment to CFFT of up to approximately $ 16 million (€ 13 million), payable in three equal annual installments following the first commercial sale of eluforsen, the first of which is due within 90 days following the first commercial sale. The Company is also obligated to make a one-time milestone payment to CFFT of up to $ 3 million (€ 2.5 million) if net sales of eluforsen exceed $ 500 million (€ 417 million) in a calendar year. Lastly, the Company is obligated to make a payment to CFFT of up to approximately $ 6 million (€ 5 million) if it transfers, sells or licenses eluforsen other than for certain clinical or development purposes, or if the Company enters into a change of control transaction prior to commercialization. However, the payment in the previous sentence may be set-off against the $ 16 million milestone payment. Either CFFT or the Company may terminate the agreement for cause, which includes the Company’s material failure to achieve certain commercialization and development milestones. The Company’s payment obligations survive the termination of the agreement. On February 9, 2018, the Company entered into an agreement with Foundation Fighting Blindness (FFB), under which FFB will provide funding of $7.5 million (€ 6.3 million) to advance QR-421a into the clinic and will receive future milestone payments. Pursuant to the terms of the agreement, the Company is obligated to make a one-time milestone payment to FFB of up to approximately $ 37.5 million (€ 31.3 million), payable in four equal annual installments following the first commercial sale of QR-421a, the first of which is due within 60 days following the first commercial sale. The Company is also obligated to make a payment to FFB of up to approximately $ 15 million (€ 12.5 million) if it transfers, sells or licenses QR-421a other than for certain clinical or development purposes, or if the Company enters into a change of control transaction. However, the payment in the previous sentence may be set-off against the $ 37.5 million milestone payment. Either FFB or the Company may terminate the agreement for cause, which includes the Company’s material failure to achieve certain commercialization and development milestones. The Company’s payment obligations survive the termination of the agreement. (d) Research and development commitments The Company has research and development commitments, mainly with CRO’s, amounting to € 7,704,000 at December 31, 2017 (2016: € 8,856,000). Of these obligations an amount of € 6,094,000 is due in 2018, the remainder is due in 1 to 5 years.

Related-Party Transactions

12 Months Ended

Dec. 31, 2017

Related-Party Transactions

Related-Party Transactions

23. Related-Party Transactions

Details of transactions between the Company and related parties are disclosed below.

(a) Compensation of the Supervisory Board

The remuneration of the supervisory board members in 2017 is set out in the table below:


	2017
	Short term	Post-employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	87	123
Mr. Henri Termeer	28	—	160	188
Mr. Antoine Papiernik	76	—	—	76
Ms. Alison Lawton	31	—	99	130
Mr. Paul Baart	84	—	—	84
Mr. James Shannon	33	—	92	125
	288	—	438	726

The remuneration of the supervisory board members in 2016 is set out in the table below:


	2016
	Short term	Post employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	52	88
Mr. Henri Termeer	31	—	51	82
Mr. Antoine Papiernik	78	—	—	78
Ms. Alison Lawton	31	—	74	105
Mr. Paul Baart	82	—	—	82
Mr. James Shannon	29	—	27	56
	287	—	204	491

The 2015 remuneration is set out in the table below:


	2015
	Short term	Post employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	12	48
Mr. Henri Termeer	34	—	11	45
Mr. Antoine Papiernik	73	—	—	73
Ms. Alison Lawton	31	—	48	79
Mr. Paul Baart	73	—	—	73
	247	—	71	318

As at December 31, 2017:

Mr. Valerio holds 1,043,420 ordinary shares in the Company, as well as 88,425 options. These options vest in four annual equal tranches of 25% starting for the first time as of the first anniversary of the date of grant. In 2016, Mr. Valerio was granted 23,989 options under the Option Plan to acquire depositary receipts issued for ordinary shares at an exercise price of € 6.08 per option. In 2017, Mr. Valerio was granted 32,164 options at an average exercise price of € 4.65 per option.

On September 12, 2017, Mr. Valerio provided a convertible loan to Amylon Therapeutics B.V. This loan is interest-bearing at an average rate of 8% per annum and is convertible into a variable number of ordinary shares within 36 months at the option of the holder or the Company in case financing criteria are met. Any unconverted loans become payable on demand after 24 months in equal quarterly terms.

Mr. Termeer passed away on May 12, 2017. His full board fee was awarded post mortem.

Mr. Antoine Papiernik does not hold any shares or options in the Company. As a managing partner of Sofinnova Partners SAS, the management company of Sofinnova Capital VII FCPR, holder of 3,625,925 ordinary shares, Mr. Papiernik may be deemed to have share voting and investment power with respect to such shares.

Ms. Lawton holds 68,973 options. In 2015, Ms. Lawton was granted 4,970 options under the Option Plan to acquire depositary receipts issued for ordinary shares at an exercise price of € 16.10 per option. In 2016, she was granted 23,989 options with an exercise price of € 6.08 per option. In 2017, she was granted 32,164 options with an average exercise price of € 4.65 per option. Under these option grants options vest in four annual equal tranches of 25% starting for the first time as of the first anniversary of the date of grant.

Mr. Paul Baart does not hold any shares or options in the Company.

Mr. James Shannon holds 61,538 ordinary shares in the Company and 65,233 options. In 2016, he was granted 33,069 options under the Option Plan to acquire depositary receipts issued for ordinary shares at an exercise price of € 4.32 per option. In 2017, he was granted 32,164 options at an exercise price of € 4.65 per option. Under these option grants options vest in four annual equal tranches of 25% starting for the first time as of the first anniversary of the date of grant.

(b) Compensation of key management

Our management board is supported by our officers, or senior management. The total remuneration of the management board and senior management in 2017 amounted to € 5,096,000 with the details set out in the table below:


	2017
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	570	8	622	1,200
Mr. R.K. Beukema2	411	15	261	687
Management Board	981	23	883	1,887
Senior Management	1,719	66	1,424	3,209
	2,700	89	2,307	5,096

Short term employee benefits includes a bonus for Mr. Daniel de Boer, of € 217,000 based on goals realised in 2017.

Short term employee benefits includes a bonus for Mr. René Beukema, of € 113,000 based on goals realised in 2017.

The total remuneration of the management board and senior management in 2016 amounted to € 3,038,000 with the details set out in the table below:


	2016
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	429	7	391	827
Mr. R.K. Beukema2	346	13	165	524
Management Board	775	20	556	1,351
Senior Management	1,020	48	619	1,687
	1,795	68	1,175	3,038

Short term employee benefits includes a bonus for Mr. Daniel de Boer of € 131,000 based on goals realised in 2016.

Short term employee benefits includes a bonus for Mr. René Beukema of € 76,000 based on goals realised in 2016.

The total remuneration of the management board and senior management in 2015 amounted to € 2,420,000 with the details set out in the table below:


	2015
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	397	7	164	568
Mr. R.K. Beukema2	313	13	88	414
Management Board	710	20	252	982
Senior Management	943	27	468	1,438
	1,653	47	720	2,420

Short term employee benefits includes a bonus for Mr. Daniel de Boer of € 100,000 based on goals realised in 2015.

Short term employee benefits includes a bonus for Mr. René Beukema of € 46,000 based on goals realised in 2015.

As at December 31, 2017:

Mr. de Boer holds 1,152,293 ordinary shares in the Company as well as 449,338 options. In 2015, Mr. de Boer was awarded a total number of 23,902 options to acquire ordinary shares at € 16.10 per option. In 2016, he was awarded 129,727 options at an exercise price of € 6.64 per option. In 2017, he was awarded 239,717 options at an exercise price of € 4.65 per option. These options vest over four years in equal annual installments and had a remaining weighted-average contractual life of 8.3 years at December 31, 2017.

Mr. Beukema holds 346,239 ordinary shares in the Company as well as 299,081 options. In 2015, Mr. Beukema was awarded 8,713 options to acquire ordinary shares at € 16.10 per option. In 2016, he was awarded 50,608 options at an exercise price of € 6.64 per option. In 2017, he was awarded 101,408 options at an exercise price of € 4.65 per option. These options vest over four years in equal annual installments and had a remaining weighted-average contractual life of 7.3 years at December 31, 2017.

ProQR does not grant any loans, advanced payments and guarantees to members of the Management and Supervisory Board.

Auditor fees

12 Months Ended

Dec. 31, 2017

Auditor fees

Auditor fees

24. Auditor fees

The fees for services provided by our external auditor, Deloitte Accountants B.V., are specified below for each of the financial years indicated:


	2017	2016	2015
	(€ in thousands)
Audit fees	175	165	193
Audit-related fees	140	39	—
Tax fees	—	—	—
All other fees	—	—	—
	315	204	193

Audit fees

Consist of aggregate fees for professional services provided in connection with the annual audit of our financial statements, the review of our quarterly financial statements, consultations on accounting matters directly related to the audit, and comfort letters, consents and assistance with and review of documents filed with the SEC.

Subsequent events	12 Months Ended
Subsequent events	Dec. 31, 2017
Subsequent events
Subsequent events	25. Subsequent events In January 2018, ProQR announced a research collaboration with Galapagos, where the Company’s Axiomer technology will be applied to certain fibrosis targets identified by Galapagos. The Axiomer platform may be applicable to more than 20,000 disease-causing mutations. The Company plans to develop its Axiomer platform in select therapeutic areas and continue to validate and create value for this novel technology through licensing, partnering and other strategic relationships. In February 2018, the Company entered into a partnership with Foundation Fighting Blindness in which ProQR will receive up to $7.5 million (€6.3 million) in funding from FFB for the pre-clinical and clinical development of QR-421a for Usher syndrome type 2A targeting mutations in exon 13.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Significant Accounting Policies

Basis of consolidation

(a) Basis of consolidation

(i) Subsidiaries

(ii) Non-controlling interests (“NCI”)

(iii) Loss of control

(iv) Transactions eliminated on consolidation

Classes of financial instruments

(b) Classes of financial instruments

Financial derivatives are valued at fair value. Upon first recognition, financial derivatives are recognized at fair value and then revalued as at balance sheet date.

Foreign currencies

(i) Foreign currency transactions

Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions.

(ii) Foreign operations

Recognition of other income

(d) Recognition of other income

Government grants — WBSO

(e) Government grants — WBSO

Employee benefits

(f) Employee benefits

(i) Short-term employee benefits

(ii) Share-based payment transactions

(iii) Pension obligations

Taxation

(g) Taxation

(i) Current tax

(ii) Deferred tax

Deferred tax is recognized on differences between the carrying amounts of assets and liabilities in the financial statements and the corresponding tax bases used in the computation of taxable profit.

Intangible assets

(h) Intangible assets

(i) Licenses

(ii) Research and development

(iii) Other intangible assets

Other intangible assets, including software, that are acquired by the Company and have finite useful lives are measured at cost less accumulated amortization and accumulated impairment losses.

(iv) Amortization

The estimated useful lives for current and comparative periods are as follows:


 software:		3	years;

Amortization methods, useful lives and residual values are reviewed at each reporting date and adjusted if appropriate.

Property, plant and equipment

(i) Property, plant and equipment

(i) Recognition and measurement

(ii) Depreciation

The estimated useful lives of property, plant and equipment for current and comparative periods are as follows:


 leasehold improvements:	5-10	years;
 laboratory equipment:	5	years;
 other:	3-5	years.

Depreciation methods, useful lives and residual values are reviewed at each reporting date and adjusted if appropriate

Impairment of tangible and intangible assets

(j) Impairment of tangible and intangible assets

Financial assets

(k) Financial assets

Loans and receivables

For all financial assets, the fair value approximates its carrying value.

Cash and cash equivalents

(l) Cash and cash equivalents

Financial liabilities and equity instruments

(m) Financial liabilities and equity instruments

Debt and equity instruments are classified as either financial liabilities or as equity in accordance with the substance of the contractual arrangement.

Equity instruments

Compound financial instruments

Interest related to the financial liability is recognised in profit or loss. On conversion, the financial liability is reclassified to equity and no gain or loss is recognised.

Other financial liabilities

Borrowings and other financial liabilities are classified as ‘non-current liabilities,’ other than liabilities with maturities up to one year, which are classified as “current liabilities”.

The Company derecognizes financial liabilities when the liability is discharged, cancelled or expired. For all financial liabilities, the fair value approximates its carrying amount.

Leases

(n) Leases

(i) Determining whether an arrangement contains a lease

At inception of an arrangement, the Company determines whether such an arrangement is or contains a lease.

(ii) Leased assets

Assets held under other leases are classified as operating leases and are not recognized in the Company’s statement of financial position.

(iii) Lease payments

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Significant Accounting Policies

Estimated useful lives for current and comparative periods


 software:		3	years;

Estimated useful lives of property, plant and equipment


 leasehold improvements:	5-10	years;
 laboratory equipment:	5	years;
 other:	3-5	years.

Financial Risk Management (Tables)

12 Months Ended

Dec. 31, 2017

Financial Risk Management

Disclosure of maturity analysis for non-derivative financial liabilities [text block]


	Less than	Between 1	Between 2
	1 year	and 2 years	and 5 years	Over 5 years
	(€ in thousands)
At December 31, 2017
Borrowings	1,960	980	5,981	—
Trade payables and other payables	6,534	—	—	—
Total	8,494	980	5,981	—

At December 31, 2016
Borrowings	—	1,839	4,860	—
Trade payables and other payables	6,710	—	—	—
Total	6,710	1,839	4,860	—

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Intangible Assets

Disclosure of detailed information about intangible assets


	Licenses	Software	Total
	(€ in thousands)	(€ in thousands)	(€ in thousands)
Balance at January 1, 2016
Cost	39	152	191
Accumulated amortization	—	(50)	(50)
Carrying amount	39	102	141

Additions	—	—	—
Amortization	—	(51)	(51)
Movement for the period	—	(51)	(51)

Balance at December 31, 2016
Cost	39	152	191
Accumulated amortization	—	(101)	(101)
Carrying amount	39	51	90

Additions	—	—	—
Amortization	—	(51)	(51)
Movement for the period	—	(51)	(51)

Balance at December 31, 2017
Cost	39	152	191
Accumulated amortization	—	(152)	(152)
Carrying amount	39	—	39

Property, Plant and Equipment ('PP&E') (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment ('PP&E")

Property, Plant and Equipment ('PP&E')


	Leasehold	Laboratory
	improvements	equipment	Other	Total
	(€ in thousands)	(€ in thousands)	(€ in thousands)	(€ in thousands)
Balance at January 1, 2016
Cost	985	1,136	651	2,772
Accumulated depreciation	(94)	(305)	(174)	(573)
Carrying amount	891	831	477	2,199

Additions	1,166	806	461	2,433
Depreciation	(499)	(340)	(332)	(1,171)
Transfer	(196)	—	196
Disposals	(23)	—	—	(23)
Movement for the period	448	466	325	1,239

Balance at December 31, 2016
Cost	1,847	1,957	1,283	5,087
Accumulated depreciation	(508)	(660)	(481)	(1,649)
Carrying amount	1,339	1,297	802	3,438

Additions	9	47	26	82
Depreciation	(294)	(409)	(312)	(1,015)
Disposals	—	—	—	—
Movement for the period	(285)	(362)	(286)	(933)

Balance at December 31, 2017
Cost	1,856	2,004	1,309	5,169
Accumulated depreciation	(802)	(1,069)	(793)	(2,664)
Carrying amount	1,054	935	516	2,505

Social Security and Other Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Social Security and Other Taxes

Social Security and Other Taxes


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Value added tax	396	395
Wage tax	—	—
	396	395

Prepayments and Other Receivables (Tables)

12 Months Ended

Dec. 31, 2017

Prepayments And Other Receivables.

Prepayments and Other Receivables


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Prepayments	1,991	1,250
Other receivables	73	1,170
	2,064	2,420

Cash and Cash Equivalents (Tables)

12 Months Ended

Dec. 31, 2017

Cash and Cash Equivalents.

Cash and Cash Equivalents


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Cash at banks	48,099	56,354
Bank deposits	—	2,846
	48,099	59,200

Shareholders’ Equity (Tables)

12 Months Ended

Dec. 31, 2017

Shareholders’ Equity

Schedule of Share capital


	Number of shares 2017	Number of shares 2016	Number of shares 2015
	Ordinary	Ordinary	Ordinary
Balance at January 1	23,346,856	23,345,965	23,338,154
Issued for cash	8,573,975	—	—
Exercise of share options	1,034	891	7,811
Treasury shares issued	4,503,149	—	—
Balance at December 31	36,425,014	23,346,856	23,345,965

Schedule of fair value of options calculated using Black-Scholes option pricing model and weighted average assumptions utilized


	Options granted		Options granted		Options granted
	in 2017		in 2016		in 2015
Risk-free interest rate	1.913	%	1.467	%	1.497	%
Expected dividend yield	—	%	—	%	—	%
Expected volatility	88.7	%	86.3	%	86.8	%
Expected life in years	5	years	5	years	5	years

Schedule of Movements in the number of options outstanding and weighted average exercise prices


	2017			2016			2015
	Number of	Average		Number of	Average		Number of	Average
	options	exercise price		options	exercise price		options	exercise price
Balance at January 1	2,205,989	€	4.88	1,108,935	€	4.19	998,765	€	2.78
Granted	1,199,447	€	4.63	1,214,126	€	5.49	125,798	€	15.27
Forfeited	(72,527)	€	5.56	(116,181)	€	4.64	(7,817)	€	4.64
Exercised	(1,034)	€	3.54	(891)	€	2.38	(7,811)	€	1.78
Expired	—		—	—		—	—		—
Balance at December 31	3,331,875	€	4.78	2,205,989	€	4.88	1,108,935	€	4.19
Exercisable at December 31	1,148,893			615,246			339,352

Non-current liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Non-current liabilities.

Borrowings


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Innovation credit	4,899	4,598
Accrued interest on innovation credit	1,683	1,099
Convertible loans	662	—
Total borrowings	7,244	5,697
Current portion	(1,960)	—
	5,284	5,697

Current liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Current Liabilities.

Current liabilities


	December 31,	December 31,
	2017	2016
	(€ in thousands)
Borrowings	1,960	—
Trade payables	546	328
Social securities and other taxes	1,019	312
Pension premiums	—	13
Deferred income	347	—
Accrued expenses and other liabilities	4,622	6,057
	8,494	6,710

Other income (Tables)

12 Months Ended

Dec. 31, 2017

Other income.

Other income


	2017	2016	2015
	(€ in thousands)
Grant income	870	1,632	3,188
Rental income from property subleases	625	196	47
	1,495	1,828	3,235

Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2017

Employee Benefits

Schedule of employee benefit


	2017	2016	2015
	(€ in thousands)
Wages and salaries	11,855	10,184	7,128
Social security costs	1,285	1,093	596
Pension costs — defined contribution plans	860	764	478
Equity-settled share based payments	4,024	2,454	1,212
	18,024	14,495	9,414
Average number of employees for the period	139.9	133.4	86.1

Schedule of employee per activity


	December 31, 2017	December 31, 2016	December 31, 2015
Research and Development	96.2	100.4	72.4
General and Administrative	34.0	32.9	27.1
Total number of employees at December 31 (converted to FTE)	130.2	133.3	99.5

Financial Income and Expense (Tables)

12 Months Ended

Dec. 31, 2017

Financial Income and Expense

Schedule of financial income and expense


	2017	2016	2015
	(€ in thousands)
Interest income:
Current accounts and deposits	90	270	501
Interest costs:
Interest on loans and borrowings	(596)	(538)	(395)
Foreign exchange result:
Net foreign exchange benefit/(loss)	(2,669)	738	6,065
	(3,175)	470	6,171

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Schedule of calculation tax charge


	2017		2016		2015
	(€ in thousands)
Income tax based on domestic rate	10,918		9,776		5,208
Tax effect of:
Non-deductible expenses	(634)		(622)		(309)
Tax incentives	—		(46)		136
Current year losses for which no deferred tax asset was recognized	(10,257)		(9,045)		(5,035)
Change in unrecognized deductible temporary differences	(25)		(63)		—
Income tax charge	2		—		—
Effective tax rate	—	%	—	%	—	%

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share

Schedule of basic earnings per share are calculated


	2017		2016		2015
Result attributable to equity holders of the Company (€ in thousands)		(43,637)		(39,103)		(20,832)
Weighted average number of shares outstanding		25,374,807		23,346,507		23,343,262
Basic (and diluted) earnings per share (€ per share)	€	(1.72)	€	(1.67)	€	(0.89)

Operational Leases (Tables)

12 Months Ended

Dec. 31, 2017

Operational Leases

Schedule of the future aggregate minimum lease payments under non-cancellable operating leases


	December 31, 2017	December 31, 2016	December 31, 2015
	(€ in thousands)
Less than 1 year	1,607	1,775	1,938
Between 1 and 5 years	3,312	5,508	7,212
More than 5 years	—	—	—
Total	4,919	7,283	9,150

Schedule of the future minimum lease payments under non-cancellable leases are receivable


	December 31, 2017	December 31, 2016	December 31, 2015
	(€ in thousands)
Less than 1 year	174	463	185
Between 1 and 5 years	—	—	—
More than 5 years	—	—	—
Total	174	463	185

Related-Party Transactions (Tables)

12 Months Ended

Dec. 31, 2017

Supervisory Board

Transactions between the Company and related parties

Schedule of transactions between company and related parties

The remuneration of the supervisory board members in 2017 is set out in the table below:


	2017
	Short term	Post-employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	87	123
Mr. Henri Termeer	28	—	160	188
Mr. Antoine Papiernik	76	—	—	76
Ms. Alison Lawton	31	—	99	130
Mr. Paul Baart	84	—	—	84
Mr. James Shannon	33	—	92	125
	288	—	438	726

The remuneration of the supervisory board members in 2016 is set out in the table below:


	2016
	Short term	Post employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	52	88
Mr. Henri Termeer	31	—	51	82
Mr. Antoine Papiernik	78	—	—	78
Ms. Alison Lawton	31	—	74	105
Mr. Paul Baart	82	—	—	82
Mr. James Shannon	29	—	27	56
	287	—	204	491

The 2015 remuneration is set out in the table below:


	2015
	Short term	Post employment	Share-based
	employee benefits	benefits	payment	Total
	(€ in thousands)
Mr. Dinko Valerio	36	—	12	48
Mr. Henri Termeer	34	—	11	45
Mr. Antoine Papiernik	73	—	—	73
Ms. Alison Lawton	31	—	48	79
Mr. Paul Baart	73	—	—	73
	247	—	71	318

Key management personnel

Transactions between the Company and related parties

Schedule of transactions between company and related parties


	2017
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	570	8	622	1,200
Mr. R.K. Beukema2	411	15	261	687
Management Board	981	23	883	1,887
Senior Management	1,719	66	1,424	3,209
	2,700	89	2,307	5,096

Short term employee benefits includes a bonus for Mr. Daniel de Boer, of € 217,000 based on goals realised in 2017.

Short term employee benefits includes a bonus for Mr. René Beukema, of € 113,000 based on goals realised in 2017.

The total remuneration of the management board and senior management in 2016 amounted to € 3,038,000 with the details set out in the table below:


	2016
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	429	7	391	827
Mr. R.K. Beukema2	346	13	165	524
Management Board	775	20	556	1,351
Senior Management	1,020	48	619	1,687
	1,795	68	1,175	3,038

Short term employee benefits includes a bonus for Mr. Daniel de Boer of € 131,000 based on goals realised in 2016.

Short term employee benefits includes a bonus for Mr. René Beukema of € 76,000 based on goals realised in 2016.

The total remuneration of the management board and senior management in 2015 amounted to € 2,420,000 with the details set out in the table below:


	2015
	Short term	Post
	employee	employment	Share-based
	benefits	benefits	payment	Total
	(€ in thousands)
Mr. D.A. de Boer1	397	7	164	568
Mr. R.K. Beukema2	313	13	88	414
Management Board	710	20	252	982
Senior Management	943	27	468	1,438
	1,653	47	720	2,420

Short term employee benefits includes a bonus for Mr. Daniel de Boer of € 100,000 based on goals realised in 2015.

Short term employee benefits includes a bonus for Mr. René Beukema of € 46,000 based on goals realised in 2015.

Auditor fees (Tables)

12 Months Ended

Dec. 31, 2017

Auditor fees

Schedule of auditors remuneration for services provided


	2017	2016	2015
	(€ in thousands)
Audit fees	175	165	193
Audit-related fees	140	39	—
Tax fees	—	—	—
All other fees	—	—	—
	315	204	193

General Information (Details)	12 Months Ended
General Information (Details)	Dec. 31, 2017
ProQR Therapeutics Holding B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics I B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics II B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics III B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics IV B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics VI B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics VII B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics VIII B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
ProQR Therapeutics IX B.V. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%
Amylon Therapeutics B.V [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	80.00%
ProQR Therapeutics I Inc. [Member]
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	100.00%

Significant Accounting Policies - Estimated useful lives (Details)	12 Months Ended
	Dec. 31, 2017
Leasehold improvements \| Minimum
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, property, plant and equipment	5 years
Leasehold improvements \| Maximum
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, property, plant and equipment	10 years
Laboratory equipment
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, property, plant and equipment	5 years
Other \| Minimum
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, property, plant and equipment	3 years
Other \| Maximum
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, property, plant and equipment	5 years
Patents
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, intangibles	10 years
Software
Disclosure Of Detailed Information About Intangibles, Property, Plant And Equipment [Line Items]
Estimated useful life, intangibles	3 years

New Standards and Interpretations not yet Adopted (Details) - Proforma Adjustment - IFRS 16 € in Millions	Dec. 31, 2017 EUR (€)
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Right-of-use assets	€ 5
Lease liabilities	€ 5

Financial Risk Management - Narrative (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Financial Risk Management
Foreign currency liability in U.S. Dollars	€ 700,000	€ 2,400,000
Foreign Currency Denominated Receivables And Trade Payable Minimum Term	30 days
Foreign Currency Denominated Receivables And Trade Payable Maximum Term	45 days
Market risk indicator used to assess the affect on cash balances	10.00%
Hypothetical Impact to Profit and Loss due to Market Risk	€ 2,500,000	2,500,000
Borrowings	€ 7,244,000	€ 5,697,000

Financial Risk Management - Undiscounted Liabilities by Maturity (Details) - EUR (€)	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about borrowings [line items]
Borrowings	€ 7,244,000	€ 5,697,000
Trade payables and other payables	546,000	328,000
Less than 1 year [Member]
Disclosure of detailed information about borrowings [line items]
Borrowings	1,960,000
Trade payables and other payables	6,534,000	6,710,000
Total	8,494,000	6,710,000
Between 1 and 2 years [Member]
Disclosure of detailed information about borrowings [line items]
Borrowings	980,000	1,839,000
Total	980,000	1,839,000
Between 2 and 5 years [Member]
Disclosure of detailed information about borrowings [line items]
Borrowings	5,981,000	4,860,000
Total	€ 5,981,000	€ 4,860,000

Intangible Assets (Details) - EUR (€)	12 Months Ended
Intangible Assets (Details) - EUR (€)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2012
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	€ 90,000	€ 141,000
Amortization	(51,000)	(51,000)
Movement for the period	(51,000)	(51,000)
Carrying amount, end of period	39,000	90,000
Cost
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	191,000	191,000
Carrying amount, end of period	191,000	191,000
Accumulated depreciation
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	(101,000)	(50,000)
Carrying amount, end of period	(152,000)	(101,000)
Licences [member]
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	39,000	39,000
Carrying amount, end of period	39,000	39,000
Licences [member] \| Cost
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	39,000	39,000
Additions			€ 39,000
Carrying amount, end of period	39,000	39,000
Software
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	51,000	102,000
Amortization	(51,000)	(51,000)
Movement for the period	(51,000)	(51,000)
Carrying amount, end of period		51,000
Software \| Cost
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	152,000	152,000
Carrying amount, end of period	152,000	152,000
Software \| Accumulated depreciation
Disclosure of detailed information about intangible assets [line items]
Carrying amount, beginning of period	(101,000)	(50,000)
Carrying amount, end of period	€ (152,000)	€ (101,000)

Property, Plant and Equipment ('PP&E') (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment
Carrying amount at beginning of period	€ 3,438,000	€ 2,199,000
Property, Plant and Equipment	3,438,000	2,199,000
Additions	82,000	2,433,000
Depreciation	(1,015,000)	(1,171,000)
Disposals		(23,000)
Movement for the period	(933,000)	1,239,000
Carrying amount at end of period	2,505,000	3,438,000
Research and development costs
Property, Plant and Equipment
Depreciation	836,000	907,000
General and administrative costs
Property, Plant and Equipment
Depreciation	179,000	264,000
Leasehold improvements
Property, Plant and Equipment
Carrying amount at beginning of period	1,339,000	891,000
Property, Plant and Equipment	1,339,000	891,000
Additions	9,000	1,166,000
Depreciation	(294,000)	(499,000)
Transfer		(196,000)
Disposals		(23,000)
Movement for the period	(285,000)	448,000
Carrying amount at end of period	1,054,000	1,339,000
Laboratory equipment
Property, Plant and Equipment
Carrying amount at beginning of period	1,297,000	831,000
Property, Plant and Equipment	1,297,000	831,000
Additions	47,000	806,000
Depreciation	(409,000)	(340,000)
Movement for the period	(362,000)	466,000
Carrying amount at end of period	935,000	1,297,000
Other
Property, Plant and Equipment
Carrying amount at beginning of period	802,000	477,000
Property, Plant and Equipment	802,000	477,000
Additions	26,000	461,000
Depreciation	(312,000)	(332,000)
Transfer		196,000
Movement for the period	(286,000)	325,000
Carrying amount at end of period	516,000	802,000
Cost
Property, Plant and Equipment
Carrying amount at beginning of period	5,087,000	2,772,000
Property, Plant and Equipment	5,087,000	2,772,000
Carrying amount at end of period	5,169,000	5,087,000
Cost \| Leasehold improvements
Property, Plant and Equipment
Carrying amount at beginning of period	1,847,000	985,000
Property, Plant and Equipment	1,847,000	985,000
Carrying amount at end of period	1,856,000	1,847,000
Cost \| Laboratory equipment
Property, Plant and Equipment
Carrying amount at beginning of period	1,957,000	1,136,000
Property, Plant and Equipment	1,957,000	1,136,000
Carrying amount at end of period	2,004,000	1,957,000
Cost \| Other
Property, Plant and Equipment
Carrying amount at beginning of period	1,283,000	651,000
Property, Plant and Equipment	1,283,000	651,000
Carrying amount at end of period	1,309,000	1,283,000
Accumulated depreciation
Property, Plant and Equipment
Carrying amount at beginning of period	(1,649,000)	(573,000)
Property, Plant and Equipment	(1,649,000)	(573,000)
Carrying amount at end of period	(2,664,000)	(1,649,000)
Accumulated depreciation \| Leasehold improvements
Property, Plant and Equipment
Carrying amount at beginning of period	(508,000)	(94,000)
Property, Plant and Equipment	(508,000)	(94,000)
Carrying amount at end of period	(802,000)	(508,000)
Accumulated depreciation \| Laboratory equipment
Property, Plant and Equipment
Carrying amount at beginning of period	(660,000)	(305,000)
Property, Plant and Equipment	(660,000)	(305,000)
Carrying amount at end of period	(1,069,000)	(660,000)
Accumulated depreciation \| Other
Property, Plant and Equipment
Carrying amount at beginning of period	(481,000)	(174,000)
Property, Plant and Equipment	(481,000)	(174,000)
Carrying amount at end of period	€ (793,000)	€ (481,000)

Social Security and Other Taxes (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016
Social Security and Other Taxes
Value added tax	€ 396	€ 395
Total Social Security and Other Taxes	€ 396	€ 395

Prepayments and Other Receivables (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepayments And Other Receivables.
Prepayments	€ 1,991	€ 1,250
Other receivables	73	1,170
Total Prepayments and Other Receivables	€ 2,064	€ 2,420

Cash and Cash Equivalents (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents.
Cash at banks	€ 48,099	€ 56,354
Bank deposits		2,846
Total cash and cash equivalents	€ 48,099	€ 59,200	€ 94,865	€ 112,736

Shareholders’ Equity - Share capital (Details)		1 Months Ended	12 Months Ended
Shareholders’ Equity - Share capital (Details)	Jun. 28, 2017 EUR (€) shares	Nov. 30, 2017 EUR (€) shares	Dec. 31, 2017 EUR (€) € / shares shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Nov. 30, 2017 $ / shares	Nov. 30, 2017 € / shares	Jun. 28, 2017 $ / shares	Jun. 28, 2017 € / shares	Oct. 02, 2015 USD ($)	Oct. 02, 2015 EUR (€)
Shareholders’ Equity
Authorized share capital \| €			€ 3,000,000
Maximum aggregate offering of ordinary shares										$ 200,000,000	€ 166,764,000
Par value per share \| € / shares			€ 0.04
shares were issued and fully paid in cash			36,425,014
Treasury shares			4,503,149	1,173,958
Shares issued in the period \| €			€ 25,685,000
Ordinary
Shareholders’ Equity
In issue at January 1			23,346,856	23,345,965	23,338,154
Issued for cash			8,573,975
Exercise of share options			1,034	891	7,811
Treasury shares issued			4,503,149
In issue at December 31 - fully paid			36,425,014	23,346,856	23,345,965
Number of shares authorised			37,500,000
Preferred
Shareholders’ Equity
Number of shares authorised			37,500,000
Market offering program
Shareholders’ Equity
In issue at December 31 - fully paid			976,477
Transaction cost \| €			€ 127,000
Net proceeds \| €			€ 4,138,000
Institutional investors
Shareholders’ Equity
In issue at December 31 - fully paid	1,200,000
Share price \| (per share)								$ 5.00	€ 4.40
Gross proceeds \| €	€ 5,278,000
Transaction cost \| €	414,000
Net proceeds \| €	€ 4,864,000
Underwritten public offering and direct offering
Shareholders’ Equity
In issue at December 31 - fully paid		6,397,498
Share price \| (per share)						$ 3.25	€ 2.76
Gross proceeds \| €		€ 17,671,000
Transaction cost \| €		988,000
Net proceeds \| €		€ 16,683,000
Cantor Fitzgerald & Co \| Ordinary
Shareholders’ Equity
Maximum aggregate offering of ordinary shares										$ 60,000,000	€ 50,029,000

Shareholders’ Equity - Share options (Details) - Stock options	12 Months Ended
	Dec. 31, 2017 EUR (€) Y	Dec. 31, 2016 EUR (€) Y	Dec. 31, 2015 EUR (€) Y
Shareholders’ Equity
Compensation expenses	€ 4,024,000	€ 2,454,000	€ 1,212,000
Compensation expenses recorded in general and administrative costs	2,059,000	1,480,000	801,000
Compensation expenses recorded in research and development costs	€ 1,965,000	€ 974,000	€ 411,000
Vesting period	4 years
Vesting period percentage	25.00%
Term options	10 years
Risk-free interest rate	1.913%	1.467%	1.497%
Expected volatility	88.70%	86.30%	86.80%
Expected life in years \| Y	5	5	5

Shareholders’ Equity - Movements in the number of options outstanding (Details) - Stock options	12 Months Ended
	Dec. 31, 2017 USD ($) EquityInstruments Y	Dec. 31, 2016 USD ($) EquityInstruments Y	Dec. 31, 2015 USD ($) EquityInstruments Y
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted average fair value per stock option	$ 3.21	$ 3.72	$ 10.35
Term options	10 years
Option life, share options granted \| Y	5	5	5
Stock options outstanding, beginning of year (in shares) \| EquityInstruments	2,205,989	1,108,935	998,765
Granted (in shares) \| EquityInstruments	1,199,447	1,214,126	125,798
Forfeited (in shares) \| EquityInstruments	(72,527)	(116,181)	(7,817)
Exercised (in shares) \| EquityInstruments	(1,034)	(891)	(7,811)
Stock options outstanding, end of the year (in shares) \| EquityInstruments	3,331,875	2,205,989	1,108,935
Exercisable stock options, end of the year (in shares) \| EquityInstruments	1,148,893	615,246	339,352
Stock options outstanding, beginning of year (in dollars per share)	$ 4.88	$ 4.19	$ 2.78
Granted (in dollars per share)	4.63	5.49	15.27
Forfeited (in dollars per share)	5.56	4.64	4.64
Exercised (in dollars per share)	3.54	2.38	1.78
Stock options outstanding, end of the year (in dollars per share)	$ 4.78	$ 4.88	$ 4.19
Weighted average life \| Y	7.9	8.3	8.3
Options exercised during the year	$ 4.32	$ 4.23	$ 19.30
Minimum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price	1.11	1.11	1.11
Maximum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price	$ 20.34	$ 20.34	$ 20.34

Non-current liabilities (Details)	12 Months Ended
Non-current liabilities (Details)	Dec. 31, 2017 EUR (€) installment	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)
Non Current Liabilities [Line Items]
Innovation credit	€ 4,899,000	€ 4,598,000
Accrued interest on innovation credit	1,683,000	1,099,000
Convertible loans	662,000
Total borrowings	7,244,000	5,697,000
Current portion	(1,960,000)
Non Current portion	5,284,000	5,697,000
Research and development expense	€ 31,153,000	€ 31,923,000	€ 23,401,000
Number of installments \| installment	3
Convertible Loans [Member]
Non Current Liabilities [Line Items]
Interest-bearing rate of credit	8.00%
Period to convert into variable number of ordinary shares	36 months
Period after which unconverted loans become payable on demand	24 months
Dutch Government Innovation Credit RVO Agency [member]
Non Current Liabilities [Line Items]
Percentage of costs incurred covered by government innovation credit	35.00%
Interest-bearing rate of credit	10.00%
Dutch Government Innovation Credit RVO Agency [member] \| Maximum
Non Current Liabilities [Line Items]
Research and development expense	€ 5,000,000

Current liabilities (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current Liabilities.
Borrowings	€ 1,960
Trade payables	546	€ 328
Social security and other taxes	1,019	312
Pension premiums		13
Deferred income	347
Accrued expenses and other liabilities	4,622	6,057
Current liabilities	€ 8,494	€ 6,710

Current liabilities - Grants (Details) - European Commission Horizon 2020 Program [member] - EUR (€) € in Millions	Dec. 31, 2017	Dec. 31, 2015
Current Liabilities [Line Items]
Current government grants		€ 4.6
Entity And Academic Partners [member]
Current Liabilities [Line Items]
Current government grants	€ 6.0	€ 6.0

Other income (Details) - EUR (€) € in Thousands	12 Months Ended
Other income (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other income.
Grant income	€ 870	€ 1,632	€ 3,188
Rental income from property subleases	625	196	47
Total other income.	€ 1,495	€ 1,828	€ 3,235

Other income - Grants (Details) € in Thousands, $ in Millions	5 Months Ended	12 Months Ended			41 Months Ended
	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)	Dec. 31, 2017 USD ($)
Other Income [Line Items]
Grant income		€ 870	€ 1,632	€ 3,188
Cystic Fibrosis Foundation Therapeutics Inc \| Maximum
Other Income [Line Items]
Grant income	€ 2,500				$ 3
European Commission Horizon 2020 Program [member]
Other Income [Line Items]
Current government grants				4,600
European Commission Horizon 2020 Program [member] \| Entity And Academic Partners [member]
Other Income [Line Items]
Current government grants	6,000	6,000		€ 6,000
Amount of funds available for qualified projects	€ 80,000,000	€ 80,000,000

Employee Benefits (Details)	12 Months Ended
Employee Benefits (Details)	Dec. 31, 2017 EUR (€) employee	Dec. 31, 2016 EUR (€) employee	Dec. 31, 2015 EUR (€) employee
Employee Benefits
Wages and salaries	€ 11,855,000	€ 10,184,000	€ 7,128,000
Social security costs	1,285,000	1,093,000	596,000
Pension costs — defined contribution plans	860,000	764,000	478,000
Equity-settled share based payments	4,024,000	2,454,000	1,212,000
Total employee benefits expense	€ 18,024,000	€ 14,495,000	€ 9,414,000
Average number of employees for the period \| employee	139.9	133.4	86.1
Research and Development \| employee	96.2	100.4	72.4
General and Administrative \| employee	34.0	32.9	27.1
Total number of employees at December 31 (converted to FTE) \| employee	130.2	133.3	99.5
WBSO subsidies received for wages and salaries	€ 723,000	€ 807,000	€ 372,000
Netherlands
Employee Benefits
Total number of employees at December 31 (converted to FTE) \| employee	125.2	128.3

Financial Income and Expense (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Income and Expense
Current accounts and deposits	€ 90	€ 270	€ 501
Interest on loans and borrowings	(596)	(538)	(395)
Net foreign exchange benefit/(loss)	(2,669)	738	6,065
Total	€ (3,175)	€ 470	€ 6,171

Income Taxes (Details) - EUR (€) € in Thousands	12 Months Ended
Income Taxes (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Income tax based on domestic rate (25%)	€ 10,918	€ 9,776	€ 5,208
Non-deductible expenses	(634)	(622)	(309)
Tax incentives		(46)	136
Current year losses for which no deferred tax asset was recognized	(10,257)	(9,045)	(5,035)
Change in unrecognized deductible temporary differences	(25)	(63)
Income tax charge	2
Provision for tax	0
Significant temporary differences	0
Tax loss carry-forwards	€ 123,900	€ 82,900	€ 46,900

Earnings Per Share (Details) - EUR (€) € / shares in Units, € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share
Result attributable to equity holders of the company (€ in thousands)	€ (43,637)	€ (39,103)	€ (20,832)
Weighted average number of shares outstanding	25,374,807	23,346,507	23,343,262
Basic (and diluted) earnings per share (€ per share)	€ (1.72)	€ (1.67)	€ (0.89)

Operating Leases - Minimum lease payments under non-cancellable operating leases (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Lease by minimum lease payments payable under noncancellable operating leases
Lease expenditure	€ 2,103,000	€ 1,849,000	€ 703,000
Lease expenditure charged to the income statement		1,849,000	703,000
Future aggregate minimum lease payments under non-cancellable operating leases	4,919,000	7,283,000	9,150,000
Less than 1 year
Operating Lease by minimum lease payments payable under noncancellable operating leases
Future aggregate minimum lease payments under non-cancellable operating leases	1,607,000	1,775,000	1,938,000
Between 1 and 5 years
Operating Lease by minimum lease payments payable under noncancellable operating leases
Future aggregate minimum lease payments under non-cancellable operating leases	€ 3,312,000	€ 5,508,000	€ 7,212,000

Operating Leases - Minimum lease payments under non-cancellable leases are receivable (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating lease by minimum lease payments receivable under noncancellable operating lease
Total sublease income	€ 625,000	€ 196,000	€ 47,000
Future minimum lease payments under non-cancellable leases are receivable	174,000	463,000	185,000
Less than 1 year
Operating lease by minimum lease payments receivable under noncancellable operating lease
Future minimum lease payments under non-cancellable leases are receivable	€ 174,000	€ 463,000	€ 185,000

Commitments and Contingencies (Details)			1 Months Ended		12 Months Ended
Commitments and Contingencies (Details)	Feb. 09, 2018 USD ($)	Feb. 09, 2018 EUR (€)	Aug. 31, 2014 USD ($)	Aug. 31, 2014 EUR (€)	Dec. 31, 2017 USD ($) installment	Dec. 31, 2017 EUR (€) installment claim	Dec. 31, 2016 EUR (€)
Commitments and Contingencies
Claims known to management related to activities of company \| claim						0
Research and development commitments \| €						€ 7,704,000	€ 8,856,000
Less than 1 year
Commitments and Contingencies
Research and development commitments \| €						6,094,000
Patent license agreement
Commitments and Contingencies
Milestone payment on achievement of development and regulatory milestones					$ 700,000	584,000
Annual license fee					$ 10,000	€ 8,000
Royalty obligation as a percentage of net sales					2.00%	2.00%
Clinical support agreement \| Cystic Fibrosis Foundation Therapeutics Inc
Commitments and Contingencies
Milestone payment on achievement of first commercial sale					$ 16,000,000	€ 13,000,000
Number of milestone payment installments \| installment					3	3
Contribution to support clinical development			$ 3,000,000	€ 2,500,000
Milestone payment on achievement of net sales exceeding threshold limit					$ 3,000,000	€ 2,500,000
Threshold sales for milestone payment					500,000,000	417,000,000
Milestone payment on transfer, sells or licenses other than for clinical or development purposes					$ 6,000,000	€ 5,000,000
Period after first commercial sale for payment of first installment					90 days	90 days
Clinical support agreement \| Foundation Fighting Blindness
Commitments and Contingencies
Milestone payment on achievement of first commercial sale					$ 37,500,000	€ 31,300,000
Number of milestone payment installments \| installment					4	4
Milestone payment on transfer, sells or licenses other than for clinical or development purposes					$ 15,000,000	€ 12,500,000
Period after first commercial sale for payment of first installment					60 days	60 days
Minimum
Commitments and Contingencies
Research And Commitments Period					1 year	1 year
Maximum
Commitments and Contingencies
Research And Commitments Period					5 years	5 years
Forecast \| Entering into partnership \| Clinical support agreement \| Foundation Fighting Blindness
Commitments and Contingencies
Contribution to support clinical development	$ 7,500,000	€ 6,300,000

Related-Party Transactions - Compensation (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supervisory Board
Transactions between the Company and related parties
Short term employee benefits	€ 288,000	€ 287,000	€ 247,000
Share-based payment	438,000	204,000	71,000
Total compensation	726,000	491,000	318,000
Mr. Dinko Valerio
Transactions between the Company and related parties
Short term employee benefits	36,000	36,000	36,000
Share-based payment	87,000	52,000	12,000
Total compensation	123,000	88,000	48,000
Mr. Henri Termeer
Transactions between the Company and related parties
Short term employee benefits	28,000	31,000	34,000
Share-based payment	160,000	51,000	11,000
Total compensation	188,000	82,000	45,000
Mr. Antoine Papiernik
Transactions between the Company and related parties
Short term employee benefits	76,000	78,000	73,000
Total compensation	76,000	78,000	73,000
Ms. Alison Lawton
Transactions between the Company and related parties
Short term employee benefits	31,000	31,000	31,000
Share-based payment	99,000	74,000	48,000
Total compensation	130,000	105,000	79,000
Mr. Paul Baart
Transactions between the Company and related parties
Short term employee benefits	84,000	82,000	73,000
Total compensation	84,000	82,000	73,000
Mr. James Shannon
Transactions between the Company and related parties
Short term employee benefits	33,000	29,000
Share-based payment	92,000	27,000
Total compensation	125,000	56,000
Key management personnel
Transactions between the Company and related parties
Short term employee benefits	2,700,000	1,795,000	1,653,000
Post-employment benefits	89,000	68,000	47,000
Share-based payment	2,307,000	1,175,000	720,000
Total compensation	5,096,000	3,038,000	2,420,000
Management Board
Transactions between the Company and related parties
Short term employee benefits	981,000	775,000	710,000
Post-employment benefits	23,000	20,000	20,000
Share-based payment	883,000	556,000	252,000
Total compensation	1,887,000	1,351,000	982,000
Mr. D.A. de Boer
Transactions between the Company and related parties
Short term employee benefits	570,000	429,000	397,000
Post-employment benefits	8,000	7,000	7,000
Share-based payment	622,000	391,000	164,000
Total compensation	1,200,000	827,000	568,000
Mr. R.K. Beukema
Transactions between the Company and related parties
Short term employee benefits	411,000	346,000	313,000
Post-employment benefits	15,000	13,000	13,000
Share-based payment	261,000	165,000	88,000
Total compensation	687,000	524,000	414,000
Senior Management
Transactions between the Company and related parties
Short term employee benefits	1,719,000	1,020,000	943,000
Post-employment benefits	66,000	48,000	27,000
Share-based payment	1,424,000	619,000	468,000
Total compensation	€ 3,209,000	€ 1,687,000	€ 1,438,000

Related-Party Transactions - Stock options (Details)		12 Months Ended
Related-Party Transactions - Stock options (Details)	Sep. 12, 2017	Dec. 31, 2017 EUR (€) Options item installment shares	Dec. 31, 2016 USD ($) Options	Dec. 31, 2016 EUR (€) Options	Dec. 31, 2015 EUR (€) Options
Sofinnova Capital VII FCPR
Transactions between the Company and related parties
Number of ordinary shares outstanding \| shares		3,625,925
Mr. Valerio
Transactions between the Company and related parties
Number of ordinary shares outstanding \| shares		1,043,420
Number of options outstanding		88,425
Number of options granted		32,164	23,989	23,989
Exercise price of options granted		€ 4.65	$ 6.08
Number of tranches \| item		4
Vesting percentage of options		25.00%
Borrowings, interest rate	8.00%
Vesting period	36 months
Period after which unconverted loans become payable on demand	24 months
Ms. Alison Lawton
Transactions between the Company and related parties
Number of options outstanding		68,973
Number of options granted		32,164	23,989	23,989	4,970
Exercise price of options granted \| €		€ 4.65		€ 6.08	€ 16.10
Number of tranches \| item		4
Vesting percentage of options		25.00%
Mr. James Shannon
Transactions between the Company and related parties
Number of ordinary shares outstanding \| shares		61,538
Number of options outstanding		65,233
Number of options granted		32,164	33,069	33,069
Exercise price of options granted		€ 4.65	$ 4.32
Number of tranches \| item		4
Vesting percentage of options		25.00%
Mr. D.A. de Boer
Transactions between the Company and related parties
Number of ordinary shares outstanding \| shares		1,152,293
Number of options outstanding		449,338
Number of options granted		239,717			23,902
Exercise price of options granted \| €		€ 4.65		€ 6.64	€ 16.10
Number of options exercised			129,727	129,727
Number of tranches \| installment		4
Bonus based on goals realised \| €		€ 217,000		€ 131,000	€ 100,000
Weighted average contractual life of options		8 years 3 months 18 days
Mr. R.K. Beukema
Transactions between the Company and related parties
Number of ordinary shares outstanding \| shares		346,239
Number of options outstanding		299,081
Number of options granted		101,408	50,608	50,608	8,713
Exercise price of options granted \| €		€ 4.65		€ 6.64	€ 16.10
Number of tranches \| installment		4
Bonus based on goals realised \| €		€ 113,000		€ 76,000	€ 46,000
Weighted average contractual life of options		7 years 3 months 18 days

Auditor fees (Details) - EUR (€) € in Thousands	12 Months Ended
Auditor fees (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Auditor fees
Audit fees	€ 175	€ 165	€ 193
Audit-related fees	140	39
Total	€ 315	€ 204	€ 193

Subsequent events (Details) - Feb. 09, 2018 € in Millions, $ in Millions	USD ($)	EUR (€)
Clinical support agreement \| Foundation Fighting Blindness \| Entering into partnership \| Forecast
Subsequent events
Contribution to support clinical development	$ 7.5	€ 6.3

Research and Development Costs	12 Months Ended
Research and Development Costs	Dec. 31, 2017
Research And Development Costs
Research and Development Costs	16. Research and Development Costs Research and development costs amounted to € 31,153,000 in 2017 (2016: € 31,923,000, 2015: € 23,401,000) and comprise allocated employee costs, the costs of materials and laboratory consumables, the costs of external studies including, amongst others, clinical studies and toxicology studies and external research, license- and IP-costs and allocated other costs.

Segment Information (Details)	12 Months Ended
Segment Information (Details)	Dec. 31, 2017 segment
Segment Information
Number of reportable segment	1