Dicerna Pharmaceuticals (DRNA) 10-Q 4 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Aug. 02, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Trading Symbol	DRNA
Entity Registrant Name	DICERNA PHARMACEUTICALS INC
Entity Central Index Key	1,399,529
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		20,753,001

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 29,187	$ 56,058
Held-to-maturity investments	40,003	38,551
Prepaid expenses and other current assets	1,482	1,532
Total current assets	70,672	96,141
NONCURRENT ASSETS:
Property and equipment-net	2,466	2,684
Assets held in restriction	1,116	1,116
Other noncurrent assets	79	82
Total noncurrent assets	3,661	3,882
TOTAL ASSETS	74,333	100,023
CURRENT LIABILITIES:
Accounts payable	3,223	2,621
Accrued expenses and other current liabilities	6,090	6,376
Deferred rent	52	4
Total current liabilities	9,365	9,001
TOTAL LIABILITIES	9,365	9,001
STOCKHOLDERS' EQUITY:
Preferred stock, $0.0001 par value-5,000,000 shares authorized, no shares issued and outstanding at June 30, 2016 and December 31, 2015
Common stock, $0.0001 par value-150,000,000 shares authorized at June 30, 2016 and December 31, 2015; 20,726,108 shares and 20,594,575 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	2	2
Additional paid-in capital	292,524	287,263
Accumulated deficit	(227,558)	(196,243)
Total stockholders' equity	64,968	91,022
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 74,333	$ 100,023

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	20,726,108	20,594,575
Common stock, shares outstanding	20,726,108	20,594,575

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Revenues		$ 184		$ 184
Operating expenses:
Research and development	$ 11,032	11,875	$ 22,296	20,567
General and administrative	4,656	4,519	9,140	9,964
Total operating expenses	15,688	16,394	31,436	30,531
Loss from operations	(15,688)	(16,210)	(31,436)	(30,347)
Interest income	66	34	121	87
Net loss	$ (15,622)	$ (16,176)	$ (31,315)	$ (30,260)
Net loss per share-basic and diluted	$ (0.75)	$ (0.86)	$ (1.51)	$ (1.65)
Weighted average shares outstanding-basic and diluted	20,726,108	18,852,814	20,706,388	18,337,030

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (31,315)	$ (30,260)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	414	339
Net amortization of premium/discount on investments	64	53
Stock-based compensation	4,795	4,981
Changes in operating assets and liabilities:
Prepaid expenses and other assets	53	(564)
Accounts payable	580	400
Accrued expenses and other liabilities	(181)	2,776
Deferred rent	48	60
Net cash used in operating activities	(25,542)	(22,215)
CASH FLOWS FROM INVESTING ACTIVITIES:
Changes in assets held in restriction		264
Purchases of property and equipment	(279)	(639)
Maturities of held-to-maturity investments	18,500	12,500
Purchases of held-to-maturity investments	(20,016)	(36,130)
Net cash used in investing activities	(1,795)	(24,005)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from stock option exercises and issuances under Employee Stock Purchase Plan	493	252
Settlement of restricted stock for tax withholding	(27)	(75)
Proceeds from public offering of common stock, net of costs		45,884
Net cash provided by financing activities	466	46,061
DECREASE IN CASH AND CASH EQUIVALENTS	(26,871)	(159)
CASH AND CASH EQUIVALENTS - Beginning of period	56,058	26,067
CASH AND CASH EQUIVALENTS - End of period	29,187	$ 25,908
SUPPLEMENTAL CASH FLOW INFORMATION:
Property and equipment purchases included in accounts payable and accrued expenses	$ 29

Description of Business and Bas

Description of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Nature of business Dicerna Pharmaceuticals, Inc. and its subsidiaries (the Company) is an RNA interference-based biopharmaceutical company focused on the discovery and development of innovative treatments for rare inherited diseases involving the liver, for other therapeutic areas in which the liver plays a key role, and for cancers that are genetically defined. The Company is using its proprietary RNA interference (RNAi) technology platform to build a broad pipeline in these therapeutic areas. The Company intends to discover, develop and commercialize novel therapeutics either on its own or in collaboration with pharmaceutical partners. The Company continues to be subject to a number of risks common to companies in similar stages of development. Principal among these risks are the uncertainties of technological innovations, which are particularly high in the field of drug discovery and development, dependence on key individuals, development of the same or similar technological innovations by the Company’s competitors and protection of proprietary technology. The Company’s ability to fund its planned preclinical and clinical operations, including completion of its clinical trials, will depend on its ability to raise capital through a combination of public or private equity offerings, debt financings, and research collaborations and license agreements. If we are unable to generate funding from one or more of these sources within a reasonable timeframe, we may have to delay, reduce or terminate our research and development programs, pre-clinical or clinical trials or undergo reductions in our workforce or other corporate restructuring activities. We cannot predict whether additional funding will be available to us on acceptable terms or at all. In May 2015, the Company completed the sale of 2,750,000 shares of common stock in a public offering of its common stock at a price to the public of $17.75 per share, resulting in proceeds to the Company of $45.4 million after deducting underwriting discounts and commissions of approximately $2.9 million and offering costs incurred by the Company of approximately $0.4 million. Basis of presentation and consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (GAAP) and in accordance with the rules and regulations of the Securities and Exchange Commission (SEC) for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for a complete set of financial statements. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position at June 30, 2016 and results of operations and cash flows for the interim periods ended June 30, 2016 and 2015. These unaudited condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. The results of the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for any other interim period or for any other future year. Summary of Significant Accounting Policies Revenue Recognition Grant revenue is recognized in the period in which the related grant research and activities are incurred, provided that the conditions under which the grant was provided have been met and the Company only has perfunctory obligations outstanding. Any amounts received in advance of revenue recognition are classified as deferred revenue in the consolidated balance sheets. Costs associated with grants are included in research and development expenses in the consolidated statements of operations.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2016
Text Block [Abstract]
Revenue Recognition	2. Revenue Recognition NIH Grants In April 2015, the National Cancer Institute (NCI), a division of the National Institutes of Health (NIH), awarded the Company a grant related to cancer treatment research. The project period for this grant covers a three month period which commenced in April 2015, with total funds available of approximately $0.2 million. The payment of the NIH grant award was based upon subcontractor and internal costs incurred that are specifically covered by the grant, and where applicable, a facilities and administrative rate that provides funding for overhead expenses. During the three and six month periods ended June 30, 2015, the Company recognized $0.2 million of revenue associated with the NIH grant award.

Held-to-maturity investments

Held-to-maturity investments	6 Months Ended
	Jun. 30, 2016
Text Block [Abstract]
Held-to-maturity investments	3. Held-to-maturity investments The Company invests its excess cash balances in short-term and long-term fixed-income investments. The Company determines the appropriate classification of investments at the time of purchase and re-evaluates such designation as of each balance sheet date. Debt securities carried at amortized cost are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity. The following tables provide information relating to held-to-maturity investments: At June 30, 2016: Amortized Gross Gross Fair Held-to-maturity investments U.S. Government treasury and agency securities $ 40,003 $ 26 $ — $ 40,029 At December 31, 2015: Amortized Gross Gross Fair Held-to-maturity investments U.S. Government treasury and agency securities $ 38,551 $ — $ (47 ) $ 38,504 The amortized cost and fair value of held-to-maturity investments by contractual maturities at June 30, 2016, are as follows (in thousands): Held-to-Maturity Amortized Fair Maturing in one year or less $ 40,003 $ 40,029 Total $ 40,003 $ 40,029

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	4. Stock-Based Compensation Stock options granted to non-employees In September 2013, the Company granted stock options to purchase 132,500 shares of common stock to non-employees with an initial fair value of $0.3 million. These stock options vest ratably over forty-eight months from the initial vesting date of July 30, 2013. Based on the terms of the non-employee stock option agreements, the Company recorded stock-based compensation expense of $0.01 million and $0.03 million for the three month and six month periods ended June 30, 2016, as compared to $0.1 million and $0.2 million in the comparable 2015 periods. The assumptions used to estimate fair value were as follows: Three Months Ended Six Months Ended June 30, 2016 Stock price $3.00 – $4.62 $3.00 – $6.56 Expected option term (in years) 3.99 – 4.11 3.99 – 4.30 Expected volatility 75.3% – 77.8% 70.6% – 77.8% Risk-free interest rate 0.87% – 1.21% 0.87% – 1.22% Expected dividend yield 0.00% 0.00% Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Stock price $13.95 – $20.07 $13.95 – $24.43 Expected option term (in years) 4.83 – 5.01 4.37 – 5.29 Expected volatility 66% – 67% 66% – 68% Risk-free interest rate 1.43% – 1.57% 1.21% – 1.57% Expected dividend yield 0.00% 0.00% As of June 30, 2016, there were 17,500 unvested stock options held by non-employees. Stock option grants to employees During the three and six month periods ended June 30, 2016, the Company granted stock options to purchase 517,500 and 1,445,275 shares of common stock to employees with grant date fair values of $1.6 million and $6.8 million, respectively, compared to 210,500 and 849,926 shares of common stock with grant date fair values of $1.8 million and $9.3 million, for the comparable three and six month periods in 2015. Employee stock-based compensation for the three and six month periods ended June 30, 2016 were $2.4 million and $4.8 million as compared to $2.6 million and $4.8 million, respectively, for the comparable 2015 periods. The assumptions used to estimate the grant date fair value for 2016 and 2015 grants were as follows: Three Months Ended Six Months Ended Stock price $3.26 – $5.55 $3.26 – $9.09 Expected option term (in years) 5.50 – 6.25 5.50 – 6.25 Expected volatility 75.1 – 75.3% 70.9 – 75.3% Risk-free interest rate 1.20% – 1.46% 1.20% – 1.71% Expected dividend yield 0.00% 0.00% Three Months Ended Six Months Ended Stock price $13.87 – $13.95 $13.87 – $24.03 Expected option term (in years) 5.50 – 6.25 5.50 – 6.25 Expected volatility 67% 67 – 69% Risk-free interest rate 1.77% – 1.81% 1.51% – 1.81% Expected dividend yield 0.00% 0.00%

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	5. Fair Value Measurements Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Valuation techniques used to measure fair value are performed in a manner to maximize the use of observable inputs and minimize the use of unobservable inputs. As a basis for considering such assumption the accounting literature establishes a three-tier value hierarchy which prioritizes the inputs used in measuring fair value as follows: (Level 1) observable inputs, such as quoted prices in active markets; (Level 2) inputs other than the quoted prices in active markets that are observable either directly or indirectly; and (Level 3) unobservable inputs for which there is little or no market data, which requires the Company to develop its own assumptions. A summary of the Company’s assets that are measured or disclosed at fair value as of June 30, 2016 and December 31, 2015 are presented below: Description 2016 Level 1 Level 2 Level 3 Cash equivalents Money market fund $ 27,741 $ 27,741 $ — $ — Held-to-maturity investments U.S. treasury securities 40,029 — 40,029 — Assets held in restriction Money market fund 1,116 — 1,116 — Total $ 68,886 $ 27,741 $ 41,145 $ — Description At December 31, 2015 Level 1 Level 2 Level 3 Cash equivalents Money market fund $ 45,557 $ 45,557 $ — $ — Held-to-maturity investments U.S. treasury securities 38,504 — 38,504 — Assets held in restriction Money market fund 1,116 — 1,116 — Total $ 85,177 $ 45,557 $ 39,620 $ — The Company’s cash equivalents, which are in money market funds, are classified within Level 1 of the fair value hierarchy because they are valued using quoted prices as of June 30, 2016 and December 31, 2015, respectively. The Company’s assets held in restriction bore interest at the prevailing market rates for instruments with similar characteristics and, accordingly, the carrying value of these instruments also approximated their fair value and the financial instruments were classified within Level 2 of the fair value hierarchy because the inputs to the fair value measurement are valued using observable inputs as of June 30, 2016 and December 31, 2015, respectively. The Company’s held-to-maturity investments bore interest at the prevailing market rates for instruments with similar characteristics. The financial instruments were classified within Level 2 of the fair value hierarchy because the inputs to the fair value measurement are observable inputs as of June 30, 2016 and December 31, 2015, respectively. For the three and six month periods ended June 30, 2016 and 2015 there were no transfers between Level 1 and Level 2.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Facility lease On July 11, 2014, the Company executed a non-cancelable operating lease for office and laboratory space in Cambridge, Massachusetts. The lease agreement obligates the Company to minimum lease payments totaling $9.5 million over the six-year lease term. The lease commenced on December 1, 2014. As part of the lease agreement, the Company established a $1.1 million letter of credit, secured by a money market account which is included in assets held in restriction at June 30, 2016 and December 31, 2015. City of Hope license agreement In September 2007, the Company entered into a license agreement with City of Hope, an independent academic research and medical center (the “Medical Center”). In consideration for the right to develop, manufacture, and commercialize products based on certain of the Medical Center’s intellectual property, the Company paid a one-time, non-refundable license fee and issued shares of common stock as consideration for the license. The Company is required to pay an annual license maintenance fee, reimburse the Medical Center for patent costs incurred, and pay an amount within the range of $5.0 million to $10.0 million upon the achievement of certain milestones, and royalties on future sales, if any. There were no sublicense and other fees accrued at June 30, 2016 and December 31, 2015. The license agreement will remain in effect until the expiration of the last patents or copyrights licensed under the agreement or until all obligations under the agreement with respect to payment of milestones have terminated or expired. The Company may terminate the license agreement at any time upon 90 days written notice to the Medical Center. The Company recorded research and development expense, related to the agreement with the Medical Center, of $0.1 million and zero for the three and six month periods ended June 30, 2016 and 2015, respectively. Plant Bioscience Limited license agreement In September 2013, the Company entered into a commercial license agreement with Plant Bioscience Limited (PBL), pursuant to which PBL has granted to the Company a license to certain of its U.S. patents and patent applications to research, discover, develop, manufacture, sell, import and export, products incorporating one or more short RNA molecules (SRMs). The Company has paid PBL a one-time, non-refundable signature fee and will pay PBL a nomination fee for any additional SRMs nominated by the Company under the agreement. The Company is further obligated to pay PBL milestone payments upon achievement of certain clinical and regulatory milestones. During 2014, the Company paid $0.1 million to PBL based on meeting a clinical milestone. In addition, PBL is entitled to receive royalties of any net sale revenue of any licensed product candidates sold by the Company. The Company did not record any research and development expense, related to this agreement, during the three and six month periods ended June 30, 2016 and 2015, respectively. Arbutus Biopharma Corporation license agreement In November 2014, the Company signed a licensing and collaboration agreement with Arbutus Biopharma Corporation (Arbutus) to license Arbutus’ LNP delivery technology for exclusive use in the Company’s primary hyperoxaluria type 1 (PH1) development program. The Company will use Arbutus’ LNP technology to deliver DCR-PH1, for the treatment of PH1. As of June 30, 2016, the Company paid $3.0 million in cumulative license fees. There were no license fees recorded in the three and six month periods ended June 30, 2016 and 2015, respectively. Arbutus is entitled to receive additional payments of $22.0 million in aggregate development milestones, plus a mid-single-digit royalty on future PH1 sales. This partnership also includes a supply agreement with Arbutus providing clinical drug supply and regulatory support.

Litigation

Litigation	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Litigation	7. Litigation On June 10, 2015, Alnylam Pharmaceuticals, Inc. (Alnylam) filed a complaint against the Company in the Superior Court of Middlesex County, Massachusetts. The complaint alleges misappropriation of confidential, proprietary, and trade secret information, as well as other related claims, in connection with the Company’s hiring of a number of former employees of Merck & Co., Inc. (Merck) and its discussions with Merck regarding the acquisition of its subsidiary, Sirna Therapeutics, Inc. (Sirna), which was subsequently acquired by Alnylam. The complaint seeks among other things, unspecified damages, attorneys’ fees, and an order permanently enjoining the Company from disclosing or using any of Alnylam’s confidential information or trade secrets. The Company believes that these allegations lack merit, has filed an answer denying all liability and intends to continue to vigorously defend all claims asserted. At this time, the Company has not recorded a liability in connection with these matters because it believes that any potential loss is neither probable nor reasonably estimable. From time to time, the Company may be subject to various claims and legal proceedings. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount is reasonably estimable, the Company will accrue a liability for the estimated loss. There were no litigation liabilities outstanding as of June 30, 2016 and December 31, 2015.

Description of Business and B13

Description of Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Nature of business	Nature of business Dicerna Pharmaceuticals, Inc. and its subsidiaries (the Company) is an RNA interference-based biopharmaceutical company focused on the discovery and development of innovative treatments for rare inherited diseases involving the liver, for other therapeutic areas in which the liver plays a key role, and for cancers that are genetically defined. The Company is using its proprietary RNA interference (RNAi) technology platform to build a broad pipeline in these therapeutic areas. The Company intends to discover, develop and commercialize novel therapeutics either on its own or in collaboration with pharmaceutical partners. The Company continues to be subject to a number of risks common to companies in similar stages of development. Principal among these risks are the uncertainties of technological innovations, which are particularly high in the field of drug discovery and development, dependence on key individuals, development of the same or similar technological innovations by the Company’s competitors and protection of proprietary technology. The Company’s ability to fund its planned preclinical and clinical operations, including completion of its clinical trials, will depend on its ability to raise capital through a combination of public or private equity offerings, debt financings, and research collaborations and license agreements. If we are unable to generate funding from one or more of these sources within a reasonable timeframe, we may have to delay, reduce or terminate our research and development programs, pre-clinical or clinical trials or undergo reductions in our workforce or other corporate restructuring activities. We cannot predict whether additional funding will be available to us on acceptable terms or at all. In May 2015, the Company completed the sale of 2,750,000 shares of common stock in a public offering of its common stock at a price to the public of $17.75 per share, resulting in proceeds to the Company of $45.4 million after deducting underwriting discounts and commissions of approximately $2.9 million and offering costs incurred by the Company of approximately $0.4 million.
Basis of presentation and consolidation	Basis of presentation and consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (GAAP) and in accordance with the rules and regulations of the Securities and Exchange Commission (SEC) for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for a complete set of financial statements. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position at June 30, 2016 and results of operations and cash flows for the interim periods ended June 30, 2016 and 2015. These unaudited condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. The results of the three and six months ended June 30, 2016 are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or for any other interim period or for any other future year.
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
Revenue Recognition	Revenue Recognition Grant revenue is recognized in the period in which the related grant research and activities are incurred, provided that the conditions under which the grant was provided have been met and the Company only has perfunctory obligations outstanding. Any amounts received in advance of revenue recognition are classified as deferred revenue in the consolidated balance sheets. Costs associated with grants are included in research and development expenses in the consolidated statements of operations.

Held-to-maturity investments (T

Held-to-maturity investments (Tables)	6 Months Ended
	Jun. 30, 2016
Text Block [Abstract]
Schedule of Held-To-Maturity Investments	The following tables provide information relating to held-to-maturity investments: At June 30, 2016: Amortized Gross Gross Fair Held-to-maturity investments U.S. Government treasury and agency securities $ 40,003 $ 26 $ — $ 40,029 At December 31, 2015: Amortized Gross Gross Fair Held-to-maturity investments U.S. Government treasury and agency securities $ 38,551 $ — $ (47 ) $ 38,504
Amortized Cost and Fair Value of Held-To-Maturity Investments	The amortized cost and fair value of held-to-maturity investments by contractual maturities at June 30, 2016, are as follows (in thousands): Held-to-Maturity Amortized Fair Maturing in one year or less $ 40,003 $ 40,029 Total $ 40,003 $ 40,029

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2016
Stock Options Granted to Non-Employees [Member]
Schedule of Valuation Assumptions	The assumptions used to estimate fair value were as follows: Three Months Ended Six Months Ended June 30, 2016 Stock price $3.00 – $4.62 $3.00 – $6.56 Expected option term (in years) 3.99 – 4.11 3.99 – 4.30 Expected volatility 75.3% – 77.8% 70.6% – 77.8% Risk-free interest rate 0.87% – 1.21% 0.87% – 1.22% Expected dividend yield 0.00% 0.00% Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Stock price $13.95 – $20.07 $13.95 – $24.43 Expected option term (in years) 4.83 – 5.01 4.37 – 5.29 Expected volatility 66% – 67% 66% – 68% Risk-free interest rate 1.43% – 1.57% 1.21% – 1.57% Expected dividend yield 0.00% 0.00%
Employee Stock Option [Member]
Schedule of Valuation Assumptions	The assumptions used to estimate the grant date fair value for 2016 and 2015 grants were as follows: Three Months Ended Six Months Ended Stock price $3.26 – $5.55 $3.26 – $9.09 Expected option term (in years) 5.50 – 6.25 5.50 – 6.25 Expected volatility 75.1 – 75.3% 70.9 – 75.3% Risk-free interest rate 1.20% – 1.46% 1.20% – 1.71% Expected dividend yield 0.00% 0.00% Three Months Ended Six Months Ended Stock price $13.87 – $13.95 $13.87 – $24.03 Expected option term (in years) 5.50 – 6.25 5.50 – 6.25 Expected volatility 67% 67 – 69% Risk-free interest rate 1.77% – 1.81% 1.51% – 1.81% Expected dividend yield 0.00% 0.00%

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Schedule of Assets Measured or Disclosed at Fair Value	A summary of the Company’s assets that are measured or disclosed at fair value as of June 30, 2016 and December 31, 2015 are presented below: Description 2016 Level 1 Level 2 Level 3 Cash equivalents Money market fund $ 27,741 $ 27,741 $ — $ — Held-to-maturity investments U.S. treasury securities 40,029 — 40,029 — Assets held in restriction Money market fund 1,116 — 1,116 — Total $ 68,886 $ 27,741 $ 41,145 $ — Description At December 31, 2015 Level 1 Level 2 Level 3 Cash equivalents Money market fund $ 45,557 $ 45,557 $ — $ — Held-to-maturity investments U.S. treasury securities 38,504 — 38,504 — Assets held in restriction Money market fund 1,116 — 1,116 — Total $ 85,177 $ 45,557 $ 39,620 $ —

Description of Business and B17

Description of Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	6 Months Ended
	May 31, 2015	Jun. 30, 2015
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds from issuance of common stock		$ 45,884
IPO [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock shares issued	2,750,000
Sale of stock price per share	$ 17.75
Proceeds from issuance of common stock	$ 45,400
Underwriting discounts and commissions	2,900
Offering cost incurred	$ 400

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Detail) - National Institutes of Health [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Funds available under revenue recognition grant	$ 0.2
Revenue associated with NIH grant award	$ 0.2	$ 0.2

Held-to-Maturity Investments -

Held-to-Maturity Investments - Schedule of Held-to-Maturity Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity investments, Amortized Cost	$ 40,003
Held-to-maturity investments, Fair Value, Total	40,029
U.S. Government Treasury and Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity investments, Amortized Cost	40,003	$ 38,551
Held-to-maturity investments, Gross Unrealized Gains	26
Held-to-maturity investments, Gross Unrealized Losses		(47)
Held-to-maturity investments, Fair Value, Total	$ 40,029	$ 38,504

Held-to-Maturity-Investments -

Held-to-Maturity-Investments - Amortized Cost and Fair Value of Held-to-Maturity Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Held-to-Maturity securities, Maturing in one year or less, Amortized Cost	$ 40,003	$ 38,551
Held to Maturity, Amortized Cost, Total	40,003
Held-to-Maturity securities, Maturing in one year or less, Fair Value	40,029
Held-to-Maturity, Fair Value, Total	$ 40,029

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	Jul. 30, 2013	Sep. 30, 2013	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 4,795	$ 4,981
Nonemployee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, granted		132,500
Stock options, granted fair value					300
Stock-based compensation expense			$ 10	$ 100	$ 30	$ 200
Stock option plan, vesting period	48 months
Unvested stock options			17,500		17,500
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, granted			517,500	210,500	1,445,275	849,926
Stock-based compensation expense			$ 2,400	$ 2,600	$ 4,800	$ 4,800
Fair value of stock options			$ 1,600	$ 1,800	$ 6,800	$ 9,300

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Valuation Assumptions (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Nonemployee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Nonemployee Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 3	$ 13.95	$ 3	$ 13.95
Expected option term (in years)	3 years 11 months 27 days	4 years 9 months 29 days	3 years 11 months 27 days	4 years 4 months 13 days
Expected volatility	75.30%	66.00%	70.60%	66.00%
Risk-free interest rate	0.87%	1.43%	0.87%	1.21%
Nonemployee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 4.62	$ 20.07	$ 6.56	$ 24.43
Expected option term (in years)	4 years 1 month 10 days	5 years 4 days	4 years 3 months 18 days	5 years 3 months 15 days
Expected volatility	77.80%	67.00%	77.80%	68.00%
Risk-free interest rate	1.21%	1.57%	1.22%	1.57%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility		67.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Employee Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 3.26	$ 13.87	$ 3.26	$ 13.87
Expected option term (in years)	5 years 6 months	5 years 6 months	5 years 6 months	5 years 6 months
Expected volatility	75.10%		70.90%	67.00%
Risk-free interest rate	1.20%	1.77%	1.20%	1.51%
Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 5.55	$ 13.95	$ 9.09	$ 24.03
Expected option term (in years)	6 years 3 months	6 years 3 months	6 years 3 months	6 years 3 months
Expected volatility	75.30%		75.30%	69.00%
Risk-free interest rate	1.46%	1.81%	1.71%	1.81%

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets Measured or Disclosed at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Held-to-maturity investments
U.S. treasury securities	$ 40,029
Assets held in restriction
Total	68,886	$ 85,177
Money Market Fund [Member]
Cash equivalents
Money market fund	27,741	45,557
Assets held in restriction
Restricted investments, at fair value	1,116	1,116
US Treasury Securities [Member]
Held-to-maturity investments
U.S. treasury securities	40,029	38,504
Level 1 [Member]
Assets held in restriction
Total	27,741	45,557
Level 1 [Member] | Money Market Fund [Member]
Cash equivalents
Money market fund	27,741	45,557
Level 2 [Member]
Assets held in restriction
Total	41,145	39,620
Level 2 [Member] | Money Market Fund [Member]
Assets held in restriction
Restricted investments, at fair value	1,116	1,116
Level 2 [Member] | US Treasury Securities [Member]
Held-to-maturity investments
U.S. treasury securities	$ 40,029	$ 38,504

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument Fair Value Carrying Value [Abstract]
Transfers between Level 1 and Level 2	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Jul. 11, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 01, 2014
Loss Contingencies [Line Items]
Research and development expense		$ 11,032,000	$ 11,875,000	$ 22,296,000	$ 20,567,000
Cambridge Massachusetts , 2014 Operating Lease Agreement [Member]
Loss Contingencies [Line Items]
Operating minimum lease payments	$ 9,500,000
Operating minimum lease payments term	6 years
Letter of credit								$ 1,100,000
Deferred rent obligation	Dec. 1, 2014
City of Hope License Agreement [Member]
Loss Contingencies [Line Items]
License agreement date				Sep. 30, 2007
Expenses related to license agreement				$ 0		$ 0
Termination of license agreement description				The Company may terminate the license agreement at any time upon 90 days written notice
Research and development expense		100,000	100,000	$ 0	0
City of Hope License Agreement [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Expenses related to license agreement				5,000,000
City of Hope License Agreement [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Expenses related to license agreement				$ 10,000,000
Plant Bioscience Limited License Agreement [Member]
Loss Contingencies [Line Items]
License agreement date				Sep. 30, 2013
Research and development expense		0	0	$ 0	0
Payments on commencement of clinical trial							$ 100,000
Arbutus Biopharma Corporation License Agreement [Member]
Loss Contingencies [Line Items]
Expenses related to license agreement				3,000,000
Aggregate development milestones and royalty				22,000,000
Additional license cost incurred		$ 0	$ 0	$ 0	$ 0

Litigation - Additional Informa

Litigation - Additional Information (Detail) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Outstanding litigation liabilities	$ 0	$ 0