Seres Therapeutics (MCRB) 10-Q 11 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Aug. 05, 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	MCRB
Entity Registrant Name	Seres Therapeutics, Inc.
Entity Central Index Key	1,609,809
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		40,274,503

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 59,824	$ 73,933
Investments	152,032	131,149
Prepaid expenses and other current assets	5,247	2,528
Total current assets	217,103	207,610
Property and equipment, net	26,985	7,751
Long-term investments	60,589
Restricted cash	1,540	1,539
Total assets	306,217	216,900
Current liabilities:
Accounts payable	4,454	5,397
Accrued expenses and other current liabilities	10,865	5,523
Deferred revenue - related party	12,012
Total current liabilities	27,331	10,920
Lease incentive obligation	9,119	586
Deferred revenue, net of current portion - related party	102,371
Total liabilities	138,821	11,506
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at June 30, 2016 and December 31, 2015; no shares issued and outstanding at June 30, 2016 and December 31, 2015
Common stock, $0.001 par value; 200,000,000 shares authorized at June 30, 2016 and December 31, 2015; 39,859,155 and 39,082,017 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	40	39
Additional paid-in capital	297,502	287,937
Accumulated other comprehensive income	83	30
Accumulated deficit	(130,229)	(82,612)
Total stockholders’ equity	167,396	205,394
Total liabilities and stockholders’ equity	$ 306,217	$ 216,900

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	39,859,155	39,082,017
Common stock, shares outstanding	39,859,155	39,082,017

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue:
Collaboration revenue - related party	$ 3,004		$ 5,714
Total revenue	3,004		5,714
Operating expenses:
Research and development expenses	22,174	$ 8,784	37,590	$ 14,345
General and administrative expenses	8,970	3,556	16,180	6,162
Total operating expenses	31,144	12,340	53,770	20,507
Loss from operations	(28,140)	(12,340)	(48,056)	(20,507)
Other income (expense):
Interest income	495	151	763	199
Interest expense	(268)	(146)	(324)	(211)
Revaluation of preferred stock warrant liability		(220)		(7)
Total other income (expense), net	227	(215)	439	(19)
Net loss	$ (27,913)	$ (12,555)	$ (47,617)	$ (20,526)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.70)	$ (1.45)	$ (1.21)	$ (2.64)
Weighted average common shares outstanding, basic and diluted	39,600,344	8,640,218	39,393,238	7,777,679
Other comprehensive income:
Unrealized gain/(loss) on investments, net of tax of $0	$ (25)	$ (8)	$ 53	$ 23
Total other comprehensive income	(25)	(8)	53	23
Comprehensive loss	$ (27,938)	$ (12,563)	$ (47,564)	$ (20,503)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Unrealized gain on investment, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Stateme6

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	$ (47,617)	$ (20,526)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	8,621	4,400
Depreciation and amortization expense	1,260	212
Gain from revaluation of preferred stock warrant liability		7
Non-cash interest expense	1	141
Accretion of discount on investments	(222)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,719)	(2,230)
Deferred revenue	114,383
Accounts payable	395	(141)
Accrued expenses and other current liabilities	1,991	141
Net cash provided by (used in) operating activities	76,093	(17,996)
Cash flows from investing activities:
Purchases of property and equipment	(9,946)	(1,649)
Purchases of investments	(206,534)	(64,250)
Sales and maturities of investments	125,335	8,725
Changes in restricted cash	(1)
Net cash used in investing activities	(91,146)	(57,174)
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs		(24)
Proceeds from exercise of stock options and common stock warrants	944	95
Repayment of notes payable		(600)
Payments of initial public offering costs		(2,148)
Net cash provided by (used in) financing activities	944	(2,677)
Net decrease in cash and cash equivalents	(14,109)	(77,847)
Cash and cash equivalents at beginning of period	73,933	114,185
Cash and cash equivalents at end of period	59,824	36,338
Supplemental disclosure of cash flow information:
Cash paid for interest	108	75
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock upon listing of the Company’s common stock on the NASDAQ		136,053
Deferred offering costs included in accounts payable and accrued expenses		780
Property and equipment purchases included in accounts payable and accrued expenses	$ 4,899	$ 718

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Seres Therapeutics, Inc. (the “Company”) was incorporated under the laws of the State of Delaware in October 2010 under the name Newco LS21, Inc. In October 2011, the Company changed its name to Seres Health, Inc., and in May 2015, the company changed its name to Seres Therapeutics, Inc. The Company is a microbiome therapeutics platform company developing a novel class of biological drugs, which are designed to restore health by repairing the function of a dysbiotic microbiome. The Company’s lead product candidate, SER-109, is intended to prevent further recurrences of Clostridium difficile The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. The Company’s product candidates are in development. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants. Unaudited Interim Financial Information The accompanying unaudited consolidated financial statements as of June 30, 2016 and for the three and six months ended June 30, 2016 and 2015 The unaudited interim financial statements have been prepared on the same basis as the audited consolidated financial statements. The condensed consolidated balance sheet at December 31, 2015 was derived from audited annual financial statements, but does not contain all of the footnote disclosures from the annual financial statements. In the opinion of management, the accompanying unaudited interim consolidated financial statements contain all adjustments which are necessary for a fair statement of the Company’s financial position as of June 30, 2016 and consolidated results of operations for the three and six months ended June 30, 2016 and its cash flows for the six months ended June 30, 2016 and 2015. Such adjustments are of a normal and recurring nature. The results of operations for the three and six months ended June 30, 2016 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2016.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The significant accounting policies and estimates used in preparation of the condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2015, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K. During the three and six months ended June 30, 2016, the Company recorded revenue in connection with its collaboration agreement. See Note 9, “Collaboration Revenue,” for additional information. Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue and expenses, and related disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: · Level 1—Quoted prices in active markets for identical assets or liabilities. · Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. · Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above. The Company’s investments in certificates of deposit are carried at amortized cost, which approximates fair value. Certain cash equivalents or investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The following table presents information about the Company’s assets as of June 30, 2016 and December 31, 2015 that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (note there were no liabilities measured at fair value on a recurring basis in either of the periods presented): Fair Value Measurements as of June 30, 2016 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 9,971 $ — $ 7,359 $ 17,330 Repurchase Agreements — 5,500 — — 5,500 Investments: Commercial Paper $ — $ 45,471 $ — $ — $ 45,471 Certificates of Deposit — 13,271 — — 13,271 Corporate Bonds — 84,728 — — 84,728 Government Securities — 51,101 — — 51,101 Treasury Bonds — 18,050 — — 18,050 $ — $ 228,092 $ — $ 7,359 $ 235,451 (1) Fair Value Measurements as of December 31, 2015 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 11,952 $ — $ 11,173 $ 23,125 Repurchase Agreements — 20,000 — — 20,000 Investments: Commercial Paper $ — $ 64,820 $ — $ — $ 64,820 Corporate Bonds — 46,490 — — 46,490 Government Securities — 15,819 — — 15,819 Treasury Bonds — 4,020 — — 4,020 $ — $ 163,101 $ — $ 11,173 $ 174,274 (1) As of June 30, 2016, the Company’s cash equivalents, which were invested in money market funds, corporate bonds, and repurchase agreements with original maturities of less than 90 days from the date of purchase, were valued based on Level 2 inputs. Repurchase agreements are agreements with banks to repurchase notes that are collateralized by U.S. government securities. As of December 31, 2015, the Company’s cash equivalents consisted of money market funds, corporate bonds, commercial paper, government securities and repurchase agreements with original maturities of less than 90 days from the date of purchase and were valued based on Level 2 inputs. Repurchase agreements are agreements with banks to repurchase notes that are collateralized by U.S. government securities. The fair value of the Company’s investments, which consisted of commercial paper, certificates of deposit, corporate bonds, government securities and treasury bonds as of June 30, 2016 and December 31, 2015 were determined using Level 2 inputs. During the three and six months ended June 30, 2016 there were no transfers between Level 1, Level 2 and Level 3. Revenue recognition The Company currently generates its revenue through collaboration and license arrangements with strategic partners for the development and commercialization of product candidates. The Company recognizes revenue in accordance with FASB ASC Topic 605, Revenue Recognition (“ASC 605”). Accordingly, revenue is recognized for each unit of accounting when all of the following criteria are met: · Persuasive evidence of an arrangement exists · Delivery has occurred or services have been rendered · The seller’s price to the buyer is fixed or determinable · Collectability is reasonably assured Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, current portion. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as long-term deferred revenue. Collaboration revenue In January 2016 the Company entered into a Collaboration and License Agreement (the “License Agreement”) with Nestec Ltd. (“NHS”), an affiliate of Nestlé Health Science US Holdings, Inc. In connection with the License Agreement, the Company received an upfront, non-refundable payment of $120,000. The Company evaluates multiple-element arrangements based on the guidance in FASB ASC Topic 605-25, Revenue Recognition-Multiple-Element Arrangements (“ASC 605-25”). Pursuant to this guidance, the Company identifies the deliverables included in the arrangement and determines: (1) whether the individual deliverables have value to the customer on a standalone basis and represent separate units of accounting or whether they must be accounted for as a combined unit of accounting; and (2) if the arrangement includes a general right of return relative to the delivered item. This evaluation requires management to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the control of the Company. In assessing whether an item has standalone value, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner, the retention of any key rights by the Company, and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). In situations where the Company has identified multiple units of accounting, the arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the selling price of a unit of accounting following the hierarchy of evidence prescribed by ASC 605-25. Accordingly, the Company determines the estimated selling price for units of accounting within each arrangement using vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”) of selling price if VSOE is not available, or best estimate of selling price (“BESP”) if neither VSOE nor TPE is available. Then, the applicable revenue recognition criteria in ASC 605-25 are applied to each of the separate units of accounting to determine the appropriate period and pattern of recognition. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605-25 are satisfied for that particular unit of accounting. The Company will recognize as revenue, upon delivery, arrangement consideration attributed to licenses that have standalone value from the other deliverables to be provided in an arrangement. For licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the Company’s estimated performance period as the arrangement would be accounted for as a single unit of accounting. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605-25 are satisfied for that particular unit of accounting. The Company will recognize as revenue arrangement consideration attributed to licenses that have standalone value from the other deliverables to be provided in an arrangement upon delivery. The Company will recognize as revenue arrangement consideration attributed to licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the Company’s estimated performance period as the arrangement would be accounted for as a single unit of accounting. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement for the single unit of accounting on a straight-line basis over the period the Company is expected to complete its performance obligations. Alternatively, if the pattern of performance in which the service is provided to the customer can be determined and objectively measurable performance measures exist, then the Company recognizes revenue under the arrangement using the proportional performance method. Revenue recognized is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the straight-line method or proportional performance method, as applicable. At the inception of an arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether: (i) the consideration is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone and the level of effort and investment required to achieve the respective milestone in making this assessment. There is considerable judgment involved in determining whether a milestone satisfies all of the criteria required to conclude that a milestone is substantive. The Company recognizes revenue associated with substantive milestones in accordance with FASB ASC Topic 605-28, Revenue Recognition-Milestone Method upon successful accomplishment of each milestone, assuming all other revenue recognition criteria are met. Milestones that are not considered substantive would be recognized as revenue over the remaining period of performance, assuming all other revenue recognition criteria are met. The Company will recognize royalty revenue in the period of sale of the related product(s), based on the underlying contract terms, provided that the reported sales are reliably measurable and the Company has no remaining performance obligations, assuming all other revenue recognition criteria are met. Refer to footnote 9 for further information related to the Company’s collaboration and license agreement with Nestec, Ltd. Net Loss per Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including the assumed exercise of stock options and warrants and unvested restricted stock. The Company applied the two-class method to calculate its basic and diluted net loss per share attributable to common stockholders for the three and six months ended June 30, 2015, as its convertible preferred stock and common stock are participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company was in a net loss position for the three and six months ended June 30, 2015 and preferred stockholders do not participate in losses. The Company’s restricted stock awards granted by the Company entitle the holder of such awards to dividends declared or paid by the board of directors, regardless of whether such awards are unvested, as if such shares were outstanding common shares at the time of the dividend. However, the unvested restricted stock awards are not entitled to share in the residual net assets (deficit) of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three and Six Months Ended June 30, 2016 2015 Stock options to purchase common stock 5,612,389 4,809,621 Unvested restricted common stock — 1,250 Warrants for the purchase of common stock — 92,127 5,612,389 4,902,998 Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients In May 2015, the FASB issued ASU 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). Refer to the Fair Value Measurements significant accounting policy for the impact of this change. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASC 842 supersedes the previous leases standard, ASC 840 Leases. The standard is effective on January 1, 2019, with early adoption permitted. The Company is in the process of evaluating the impact of this new guidance. In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting The Company is in the process of evaluating the impact of this new guidance. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The new standard changes the impairment model for most financial assets and certain other instruments. Under the new standard, entities holding financial assets and net investment in leases that are not accounted for at fair value through net income to be presented at the net amount expected to be collected. An allowance for credit losses will be a valuation account that will be deducted from the amortized cost basis of the financial asset to present the net carrying value at the amount expected to be collected on the financial asset. The new standard will be effective for the Company on January 1, 2020. The adoption of this standard is not expected to have a material impact on the Company’s financial position or results of operations. Reclassifications Certain amounts reported in the prior year financial statements have been reclassified for comparative purposes to conform with the presentation in the current year condensed consolidated financial statements.

Investments

Investments	6 Months Ended
	Jun. 30, 2016
Investments Debt And Equity Securities [Abstract]
Investments	3. Investments As of June 30, 2016 and December 31, 2015, the fair value of available-for-sale investments by type of security was as follows: June 30, 2016 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Commercial Paper $ 45,413 $ 58 $ — $ 45,471 Certificates of Deposit $ 13,271 $ — — $ 13,271 Corporate Bonds 84,736 27 (35 ) 84,728 Government Securities 51,088 16 (3 ) 51,101 Treasury Bonds 18,029 21 — 18,050 $ 212,537 $ 122 $ (38 ) $ 212,621 December 31, 2015 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Commercial Paper $ 64,733 $ 87 $ — $ 64,820 Corporate Bonds 46,538 — (48 ) 46,490 Government Securities 15,823 — (4 ) 15,819 Treasury Bonds 4,022 — (2 ) 4,020 $ 131,116 $ 87 $ (54 ) $ 131,149 Investments with original maturities of less than 90 days are included in cash and cash equivalents on the consolidated balance sheets and are not included in the table above. Investments with maturities of less than 12 months are considered current and those investments with maturities greater than 12 months are considered non-current. As of December 31, 2015, the Company’s commercial paper, corporate bonds, government securities and treasury bonds had remaining maturities of less than 12 months.

Property and Equipment, Net

Property and Equipment, Net	6 Months Ended
	Jun. 30, 2016
Property Plant And Equipment [Abstract]
Property and Equipment, Net	4. Property and Equipment, Net Property and equipment, net consisted of the following: June 30, 2016 December 31, 2015 Laboratory equipment $ 6,804 $ 4,370 Computer equipment 971 408 Furniture and office equipment 788 285 Leasehold improvements 9,965 1,856 Construction in progress 10,692 1,843 29,220 8,762 Less: Accumulated depreciation and amortization (2,235 ) (1,011 ) $ 26,985 $ 7,751 Construction in progress at June 30, 2016 was comprised primarily of leasehold improvements and laboratory equipment purchased in connection with the build-out of office and laboratory space at our new headquarters at 200 Sidney Street in Cambridge, Massachusetts. Depreciation and amortization expense was $874, $1,260, $119 and $212 for the three and six months ended June 30, 2016 and 2015, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2016
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: June 30, 2016 December 31, 2015 Development and manufacturing costs $ 3,258 $ 1,436 Payroll and payroll-related costs 2,375 2,756 Professional fees 449 184 Facility 4,662 1,053 Other 121 94 $ 10,865 $ 5,523

Preferred Stock Warrant Liabili

Preferred Stock Warrant Liability	6 Months Ended
	Jun. 30, 2016
Class Of Stock Disclosures [Abstract]
Preferred Stock Warrant Liability	6 . Preferred Stock Warrant Liability In September 2013, the Company issued a warrant to purchase 92,127 shares of Series A-2 convertible preferred stock in connection with its loan and security agreement. The warrant was immediately exercisable at an exercise price of $1.78 per share and has a contractual term of ten years from issuance. The fair value of the warrant at issuance was estimated to be $156 and was recorded as a debt discount and as a preferred stock warrant liability. The Company classified the warrant to purchase shares of its Series A-2 convertible preferred stock as a liability on its consolidated balance sheets and subsequently re-measured to fair value at each balance sheet date. Changes in fair value of the warrant were recognized as a component of other income (expense), net, in the consolidated statement of operations and comprehensive loss. In connection with the automatic conversion of the Company’s convertible preferred stock, which occurred upon the listing of the Company’s common stock on the NASDAQ on June 26, 2015, the preferred stock warrant became a warrant to purchase common stock. The Company performed the final mark to market adjustment on the preferred stock warrant using the fair value of the underlying common shares of $18.00 per share on June 26, 2015 and recorded the change in fair value in other income (expense), net in the consolidated statement of operations and comprehensive loss. The preferred stock warrant liability was then reclassified to additional paid-in-capital as it became a warrant to purchase common stock. There was no balance related to the preferred stock warrant liability as of June 30, 2016 and December 31, 2015. The Company recorded losses of $220 and $7 for the three and six months ended June 30, 2015 to reflect the change in fair value of this preferred stock warrant. The following assumptions and inputs were used in determining the fair value of the preferred stock warrant liability valued using the Black-Scholes option-pricing model: Six Months Ended June 30, 2015 Risk-free interest rate 2.40 % Expected term (in years) 8.2 Expected volatility 91.2 % Expected dividend yield 0 % Fair value of Series A-2 convertible preferred stock $ 17.26

Preferred Stock

Preferred Stock	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Preferred Stock	7. Preferred Stock On July 1, 2015, in connection with the closing of the IPO, the Company effected its Restated Certificate of Incorporation, which authorizes the Company to issue 10,000,000 shares of preferred stock, $0.001 par value per share.

Stockholders_ Equity Common Sto

Stockholders’ Equity Common Stock	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Stockholders’ Equity Common Stock	8 . Stockholders’ Equity Common Stock On July 1, 2015, the Company completed an IPO, and issued and sold 8,545,138 shares of common stock at a public offering price of $18.00 per share, resulting in net proceeds of approximately $139,267 after deducting underwriting discounts and commissions and other offering expenses totaling $3,748. The shares issued upon closing of the IPO included 1,114,583 shares of the Company’s common stock, which were sold to the underwriters pursuant to the full exercise of their option to purchase additional shares of common stock. Upon the listing of the Company’s common stock on the NASDAQ on June 26, 2015, all outstanding shares of the Company’s convertible preferred stock automatically converted into 22,866,987 shares of the Company’s common stock. As of December 31, 2014, the Company’s Amended and Restated Certificate of Incorporation, as further amended, authorized the Company to issue 38,000,000 shares of common stock, $0.001 par value per share. On July 1, 2015, in connection with the closing of the IPO, the Company effected its Restated Certificate of Incorporation, which authorizes the Company to issue 200,000,000 shares of common stock, $0.001 par value per share. Stock Options The following table summarizes the Company’s stock option activity since December 31, 2015: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding as of December 31, 2015 5,026,246 $ 8.01 8.70 $ 136,945 Granted 1,418,625 28.05 Exercised (777,138 ) 1.21 Forfeited (55,344 ) 13.48 Outstanding as of June 30, 2016 5,612,389 $ 13.96 8.41 $ 88,441 Options exercisable as of June 30, 2016 1,793,436 $ 6.00 7.52 $ 41,438 Options vested and expected to vest as of June 30, 2016 5,491,857 $ 13.85 8.40 $ 87,103 The weighted average grant-date fair value of stock options granted during the three and six months ended June 30, 2016 was $20.64 and $19.87 per share, respectively. The Company has granted performance-based stock options to certain employees. These stock options are exercisable only upon achievement of specified performance targets. As of June 30, 2016, none of these options were exercisable because none of the specified performance targets had been achieved. During the three months ended June 30, 2016, the Company has determined that the achievement of 60,000 of these specified performance targets is probable and has recorded expense of $212. The grant date fair value of these awards was $3.92 per share. Stock-based Compensation Expense The Company recorded stock-based compensation expense related to stock options and restricted common stock in the following expense categories of its consolidated statements of operations and comprehensive loss: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Research and development expenses $ 2,896 $ 1,891 $ 5,082 $ 2,514 General and administrative expenses 1,821 1,182 3,539 1,886 $ 4,717 $ 3,073 $ 8,621 $ 4,400

Collaboration Revenue

Collaboration Revenue	6 Months Ended
	Jun. 30, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Revenue	9 . Collaboration Revenue Nestec Ltd. In January 2016 the Company entered into a Collaboration and License Agreement with Nestec Ltd. (“NHS”), an affiliate of Nestlé Health Science US Holdings, Inc., a significant stockholder of the Company, for the development and commercialization of certain product candidates in development for the treatment and management of CDI and IBD, including ulcerative colitis and Crohn’s disease. The License Agreement will support the development of the Company’s portfolio of products for CDI and IBD in markets outside of the United States and Canada (“the Licensed Territory”). The Company has retained full commercial rights to its entire portfolio of product candidates with respect to the United States and Canada. Under the License Agreement, the Company granted to NHS an exclusive, royalty-bearing license to develop and commercialize, in the Licensed Territory, certain products based on its microbiome technology that are being developed for the treatment of CDI and IBD, including SER-109, SER-262, SER-287 and SER-301, or, collectively, the NHS Collaboration Products. The License Agreement sets forth the Company’s and NHS’ respective obligations for development, commercialization, regulatory and manufacturing and supply activities for the NHS Collaboration Products with respect to the licensed fields and the Licensed Territory. Under the License Agreement, the Company’s and NHS’ development activities will be governed by global and regional development plans, including the conduct of additional clinical studies. The Company has agreed to manufacture and supply NHS Collaboration Products to support development and commercialization of NHS Collaboration Products in the licensed fields and in the Licensed Territory. NHS will have the right to obligate the Company to transfer technology necessary to manufacture Collaboration Products in the event that the Company materially fails to meet its supply commitments to NHS under the commercial supply agreement. The Company has also agreed to use diligent efforts to develop NHS Collaboration Products under a global development plan and to obtain approval for such NHS Collaboration Products in the European Union, or EU. In exchange for the license, NHS agreed to pay the Company an upfront cash payment of $120,000, which the Company received in February 2016. NHS also agreed to pay the Company tiered royalties, at percentages ranging from the high single digits to high teens, of net sales of NHS Collaboration Products in the Licensed Territory. The Company is eligible to receive up to $295,000 in development milestone payments, $365,000 in regulatory payments and up to an aggregate of $1,125,000 for the achievement of certain commercial milestones related to the sales of NHS Collaboration Products. For the development of NHS Collaboration Products for IBD under a global development plan, the Company agreed to pay the costs of clinical trials of such products up to and including Phase 2 clinical trials, and 67% of the costs for Phase 3 and other clinical trials of such products, with NHS bearing the remaining 33% of such costs. For other clinical development of NHS Collaboration Products for IBD, the Company agreed to pay the costs of such activities to support approval in the United States and Canada, and NHS agreed to bear the cost of such activities to support approval of NHS Collaboration Products in the Licensed Territory. With respect to development of NHS Collaboration Products for CDI under a global development plan, the Company agreed to pay all costs of an ongoing Phase 2 clinical trial for SER-109 and of Phase 3 clinical trials for SER-109. The Company agreed to bear all costs of conducting any Phase 1 or Phase 2 clinical trials under a global development plan for NHS Collaboration Products other than SER-109 for CDI. The Company agreed to pay 67% and NHS agreed to pay 33% of other costs of Phase 3 clinical trials conducted for NHS Collaboration Products other than SER-109 for CDI under a global development plan. For other clinical development of NHS Collaboration Products for CDI, the Company agreed to pay costs of such development activities to support approval in the United States and Canada, and NHS agreed to bear the cost of such activities to support approval of NHS Collaboration Products in the Licensed Territory. The License Agreement continues in effect until terminated by either the Company or NHS on the following bases: (i) NHS may terminate the License Agreement in the event of serious safety issues related to any of the NHS Collaboration Products; (ii) the Company may terminate the License Agreement if NHS challenges the validity or enforceability of any of our licensed patents; and (iii) either the Company or NHS may terminate the License Agreement in the event of the other party’s uncured material breach or insolvency. Upon termination of the License Agreement, all licenses granted to NHS by the Company will terminate, and all rights in and to the NHS Collaboration Products in the Licensed Territory will revert to the Company. If the Company commits a material breach of the License Agreement, NHS may elect not to terminate the License Agreement but instead apply specified adjustments to its payment obligations and other terms and conditions of the License Agreement. The License Agreement contains customary representations and warranties, intellectual property protection provisions, certain indemnification rights in favor of each party and customary confidentiality provisions and limitations of liability. At the inception of the License Agreement, the Company identified the following deliverables: (i) a license to develop and commercialize the NHS Collaboration Products in the Licensed Territory, (ii) obligation to perform research and development services, (iii) participation on a joint steering committee (“JSC”), and (iv) manufacturing services to provide clinical supply to complete future clinical trials. The Company also identified a contingent deliverable, the obligation to perform manufacturing services to provide commercial supply if commercialization occurs, which is contingent upon regulatory approval. This contingent deliverable has been excluded from the initial allocation and will be treated as a separate unit of accounting when and if delivered. The Company concluded that none of the four deliverables identified at the inception of the License Agreement has standalone value from the other undelivered elements. Accordingly, all deliverables represent a single unit of accounting. All consideration received relating to the four identified deliverables that comprise the single unit of accounting will be recognized over the period of performance. The period of performance will be through the completion of development services for the NHS Collaboration Products which has been estimated to be ten years. The Company will periodically review and, if necessary, revise the estimated development period. The Company will recognize revenue utilizing a time-based proportional performance model where revenue related to each payment is recognized over the ten year performance period. As of June 30, 2016, the only consideration that is fixed and determinable is the non-refundable upfront payment of $120,000 and $97 for the reimbursement of development services since the inception of the arrangement. For additional consideration that could be received for research and development services and/or manufacturing services for clinical supply, the Company will recognize a cumulative catch-up for the amount of time that has elapsed and spread the unrecognized portion over the remaining performance period. Development and regulatory milestones that involve substantial effort on the Company’s part and the achievement of which are not considered probable at the inception of the License Agreement are considered substantive milestones, and will be recognized in their entirety in the period in which the milestone is achieved, assuming all other revenue recognition criteria are met. All commercial milestones will be recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. Royalties will be recorded as revenue in the period they are earned assuming all other revenue recognition criteria are met. During the three and six months ended June 30, 2016, the Company recognized $3,004 and $5,714, respectively, of related party revenue associated with the License Agreement. As of June 30, 2016, there was $114,383 of deferred revenue related to the License Agreement, which is classified as current or non-current in the consolidated balance sheets based on the Company’s estimate of revenue that will be recognized within the next twelve months. All costs associated with the License Agreement are recorded in research and development expense in the condensed consolidated statements of operations and comprehensive loss.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	10 . Income Taxes The Company did not provide for any income taxes for six month period ended June 30, 2016 or 2015. The Company has evaluated the positive and negative evidence bearing upon the realizability of its U.S. net deferred tax assets. As required by the provisions of ASC 740, Income Taxes As of June 30, 2016 and December 31, 2015, the Company had no accrued interest or tax penalties recorded. The Company files income tax returns in the U.S. and various state jurisdictions. The Company is no longer subject to U.S. federal income tax examinations by tax authorities for years before 2012. However, to the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated my still be adjusted upon examination by the Internal Revenue Service or state tax authorizes to the extent it is utilized in a future period. There are no currently ongoing or pending examinations in any jurisdictions.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11 . Commitments and Contingencies Leases The Company previously leased office and laboratory space with a lease term expiring in January 2018 and no extension periods. In May 2016, upon mutual agreement with the landlord, the Company accelerated the termination of the operating lease to June 30, 2016. Upon termination of the lease, the Company recorded a benefit to rent expense of $136 to write off amounts previously recorded as deferred rent. The outstanding security deposit of $119, which is secured by a cash collateralized letter of credit, will remain in place until 90 days after termination in accordance with the original lease. On November 11, 2015, the Company entered into a non-cancelable property lease with BMR-Sidney Research Campus LLC (“BMR”) for 83,396 square feet of office, laboratory and pilot manufacturing space at 200 Sidney Street, Cambridge, Massachusetts. The lease term commenced in March 2016 and ends in November 2023. The Company has the option to extend the lease twice, each for a five-year period. The Company moved its corporate headquarters to this location in April 2016. BMR will contribute a total of $12,509 toward the cost of tenant improvements. BMR’s contribution toward the cost of tenant improvements is recorded as a lease incentive obligation on our consolidated balance sheet. The lease incentive obligation is amortized to our consolidated statement of operations as reductions to rent expense over the lease term. As of June 30, 2016, we have recorded a lease incentive obligation of $9,119. During the three and six months ended June 30, 2016 and 2015, the Company recognized $787, $1,180, $354 and $540, respectively, of rental expense related to office and laboratory space. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of June 30, 2016 or December 31, 2015.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	12 . Related Party Transactions In October 2010, the Company entered into a services agreement with Flagship Ventures Management, Inc., an affiliate of one of its stockholders, Flagship Venture Funds, to provide general and administrative services to the Company, including the employer portions of employee health and dental benefit plans for Seres Therapeutics employees and consulting services. The Company made payments under the agreement of $1, $17, $131 and $249 during the three and six months ended June 30, 2016 and 2015, respectively. T here were no amounts due to Flagship Ventures Management, Inc. related to the services agreement as of June 30, 2016 and December 31, 2015. As described in Note 9, in January 2016 the Company entered into a License Agreement with NHS for the development and commercialization of certain product candidates in development for the treatment and management of CDI and IBD, including ulcerative colitis and Crohn’s disease. NHS is a related party since NHS is an affiliate of Nestlé Health Science, one of the Company’s significant stockholders. During the three and six months ended June 30, 2016, the Company recognized $3,004 and $5,714 of related party revenue associated with the License Agreement. As of June 30, 2016, there was $114,383 of deferred revenue related to the License Agreement, which is classified as current or non-current in the consolidated balance sheets. The Company has made no payments to NHS during the three and six months ended June 30, 2016. There is $97 due from NHS as of June 30, 2016 for the reimbursement of development costs.

401(k) Savings Plan

401(k) Savings Plan	6 Months Ended
	Jun. 30, 2016
Compensation And Retirement Disclosure [Abstract]
401(k) Savings Plan	13. 401(k) Savings Plan The Company has a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Effective January 1, 2016, the Company has elected to match 50% of the first 6% of an employee’s deferral. Company contributions are expensed in the year for which they are declared. During the three and six months ended June 30, 2016, the Company recorded expense of $188 for accrued 401(k) match contributions.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2016
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events On August 2, 2016, the Company notified its Phase 3 SER-109 clinical research organization (“CRO”) partner that it intends to terminate its agreement with the CRO for work in connection with a planned global, pivotal Phase 3 trial for SER-109. The work performed to date under this agreement was tied to start-up activities of the planned trial. The Company has $690 of prepaid expense related to this agreement on its balance sheet as of June 30, 2016. The Company expects a portion of this amount to be recorded as research and development expense during the remainder of the year ending December 31, 2016.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue and expenses, and related disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: · Level 1—Quoted prices in active markets for identical assets or liabilities. · Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. · Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above. The Company’s investments in certificates of deposit are carried at amortized cost, which approximates fair value. Certain cash equivalents or investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The following table presents information about the Company’s assets as of June 30, 2016 and December 31, 2015 that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (note there were no liabilities measured at fair value on a recurring basis in either of the periods presented): Fair Value Measurements as of June 30, 2016 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 9,971 $ — $ 7,359 $ 17,330 Repurchase Agreements — 5,500 — — 5,500 Investments: Commercial Paper $ — $ 45,471 $ — $ — $ 45,471 Certificates of Deposit — 13,271 — — 13,271 Corporate Bonds — 84,728 — — 84,728 Government Securities — 51,101 — — 51,101 Treasury Bonds — 18,050 — — 18,050 $ — $ 228,092 $ — $ 7,359 $ 235,451 (1) Fair Value Measurements as of December 31, 2015 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 11,952 $ — $ 11,173 $ 23,125 Repurchase Agreements — 20,000 — — 20,000 Investments: Commercial Paper $ — $ 64,820 $ — $ — $ 64,820 Corporate Bonds — 46,490 — — 46,490 Government Securities — 15,819 — — 15,819 Treasury Bonds — 4,020 — — 4,020 $ — $ 163,101 $ — $ 11,173 $ 174,274 (1) As of June 30, 2016, the Company’s cash equivalents, which were invested in money market funds, corporate bonds, and repurchase agreements with original maturities of less than 90 days from the date of purchase, were valued based on Level 2 inputs. Repurchase agreements are agreements with banks to repurchase notes that are collateralized by U.S. government securities. As of December 31, 2015, the Company’s cash equivalents consisted of money market funds, corporate bonds, commercial paper, government securities and repurchase agreements with original maturities of less than 90 days from the date of purchase and were valued based on Level 2 inputs. Repurchase agreements are agreements with banks to repurchase notes that are collateralized by U.S. government securities. The fair value of the Company’s investments, which consisted of commercial paper, certificates of deposit, corporate bonds, government securities and treasury bonds as of June 30, 2016 and December 31, 2015 were determined using Level 2 inputs. During the three and six months ended June 30, 2016 there were no transfers between Level 1, Level 2 and Level 3.
Revenue recognition	Revenue recognition The Company currently generates its revenue through collaboration and license arrangements with strategic partners for the development and commercialization of product candidates. The Company recognizes revenue in accordance with FASB ASC Topic 605, Revenue Recognition (“ASC 605”). Accordingly, revenue is recognized for each unit of accounting when all of the following criteria are met: · Persuasive evidence of an arrangement exists · Delivery has occurred or services have been rendered · The seller’s price to the buyer is fixed or determinable · Collectability is reasonably assured Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, current portion. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as long-term deferred revenue.
Collaboration revenue	Collaboration revenue In January 2016 the Company entered into a Collaboration and License Agreement (the “License Agreement”) with Nestec Ltd. (“NHS”), an affiliate of Nestlé Health Science US Holdings, Inc. In connection with the License Agreement, the Company received an upfront, non-refundable payment of $120,000. The Company evaluates multiple-element arrangements based on the guidance in FASB ASC Topic 605-25, Revenue Recognition-Multiple-Element Arrangements (“ASC 605-25”). Pursuant to this guidance, the Company identifies the deliverables included in the arrangement and determines: (1) whether the individual deliverables have value to the customer on a standalone basis and represent separate units of accounting or whether they must be accounted for as a combined unit of accounting; and (2) if the arrangement includes a general right of return relative to the delivered item. This evaluation requires management to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the control of the Company. In assessing whether an item has standalone value, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner, the retention of any key rights by the Company, and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). In situations where the Company has identified multiple units of accounting, the arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the selling price of a unit of accounting following the hierarchy of evidence prescribed by ASC 605-25. Accordingly, the Company determines the estimated selling price for units of accounting within each arrangement using vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”) of selling price if VSOE is not available, or best estimate of selling price (“BESP”) if neither VSOE nor TPE is available. Then, the applicable revenue recognition criteria in ASC 605-25 are applied to each of the separate units of accounting to determine the appropriate period and pattern of recognition. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605-25 are satisfied for that particular unit of accounting. The Company will recognize as revenue, upon delivery, arrangement consideration attributed to licenses that have standalone value from the other deliverables to be provided in an arrangement. For licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the Company’s estimated performance period as the arrangement would be accounted for as a single unit of accounting. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605-25 are satisfied for that particular unit of accounting. The Company will recognize as revenue arrangement consideration attributed to licenses that have standalone value from the other deliverables to be provided in an arrangement upon delivery. The Company will recognize as revenue arrangement consideration attributed to licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the Company’s estimated performance period as the arrangement would be accounted for as a single unit of accounting. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement for the single unit of accounting on a straight-line basis over the period the Company is expected to complete its performance obligations. Alternatively, if the pattern of performance in which the service is provided to the customer can be determined and objectively measurable performance measures exist, then the Company recognizes revenue under the arrangement using the proportional performance method. Revenue recognized is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the straight-line method or proportional performance method, as applicable. At the inception of an arrangement that includes milestone payments, the Company evaluates whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether: (i) the consideration is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone and the level of effort and investment required to achieve the respective milestone in making this assessment. There is considerable judgment involved in determining whether a milestone satisfies all of the criteria required to conclude that a milestone is substantive. The Company recognizes revenue associated with substantive milestones in accordance with FASB ASC Topic 605-28, Revenue Recognition-Milestone Method upon successful accomplishment of each milestone, assuming all other revenue recognition criteria are met. Milestones that are not considered substantive would be recognized as revenue over the remaining period of performance, assuming all other revenue recognition criteria are met. The Company will recognize royalty revenue in the period of sale of the related product(s), based on the underlying contract terms, provided that the reported sales are reliably measurable and the Company has no remaining performance obligations, assuming all other revenue recognition criteria are met. Refer to footnote 9 for further information related to the Company’s collaboration and license agreement with Nestec, Ltd.
Net Loss per Share	Net Loss per Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including the assumed exercise of stock options and warrants and unvested restricted stock. The Company applied the two-class method to calculate its basic and diluted net loss per share attributable to common stockholders for the three and six months ended June 30, 2015, as its convertible preferred stock and common stock are participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company was in a net loss position for the three and six months ended June 30, 2015 and preferred stockholders do not participate in losses. The Company’s restricted stock awards granted by the Company entitle the holder of such awards to dividends declared or paid by the board of directors, regardless of whether such awards are unvested, as if such shares were outstanding common shares at the time of the dividend. However, the unvested restricted stock awards are not entitled to share in the residual net assets (deficit) of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three and Six Months Ended June 30, 2016 2015 Stock options to purchase common stock 5,612,389 4,809,621 Unvested restricted common stock — 1,250 Warrants for the purchase of common stock — 92,127 5,612,389 4,902,998
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients In May 2015, the FASB issued ASU 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). Refer to the Fair Value Measurements significant accounting policy for the impact of this change. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASC 842 supersedes the previous leases standard, ASC 840 Leases. The standard is effective on January 1, 2019, with early adoption permitted. The Company is in the process of evaluating the impact of this new guidance. In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting The Company is in the process of evaluating the impact of this new guidance. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The new standard changes the impairment model for most financial assets and certain other instruments. Under the new standard, entities holding financial assets and net investment in leases that are not accounted for at fair value through net income to be presented at the net amount expected to be collected. An allowance for credit losses will be a valuation account that will be deducted from the amortized cost basis of the financial asset to present the net carrying value at the amount expected to be collected on the financial asset. The new standard will be effective for the Company on January 1, 2020. The adoption of this standard is not expected to have a material impact on the Company’s financial position or results of operations.
Reclassifications	Reclassifications Certain amounts reported in the prior year financial statements have been reclassified for comparative purposes to conform with the presentation in the current year condensed consolidated financial statements.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents information about the Company’s assets as of June 30, 2016 and December 31, 2015 that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (note there were no liabilities measured at fair value on a recurring basis in either of the periods presented): Fair Value Measurements as of June 30, 2016 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 9,971 $ — $ 7,359 $ 17,330 Repurchase Agreements — 5,500 — — 5,500 Investments: Commercial Paper $ — $ 45,471 $ — $ — $ 45,471 Certificates of Deposit — 13,271 — — 13,271 Corporate Bonds — 84,728 — — 84,728 Government Securities — 51,101 — — 51,101 Treasury Bonds — 18,050 — — 18,050 $ — $ 228,092 $ — $ 7,359 $ 235,451 (1) Fair Value Measurements as of December 31, 2015 Using: Level 1 Level 2 Level 3 Not Subject to Leveling (1) Total Assets: Cash Equivalents $ — $ 11,952 $ — $ 11,173 $ 23,125 Repurchase Agreements — 20,000 — — 20,000 Investments: Commercial Paper $ — $ 64,820 $ — $ — $ 64,820 Corporate Bonds — 46,490 — — 46,490 Government Securities — 15,819 — — 15,819 Treasury Bonds — 4,020 — — 4,020 $ — $ 163,101 $ — $ 11,173 $ 174,274 (1)
Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share	The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three and Six Months Ended June 30, 2016 2015 Stock options to purchase common stock 5,612,389 4,809,621 Unvested restricted common stock — 1,250 Warrants for the purchase of common stock — 92,127 5,612,389 4,902,998

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2016
Investments Debt And Equity Securities [Abstract]
Schedule of Fair Value of Available-for-Sale Investments by Type of Security	As of June 30, 2016 and December 31, 2015, the fair value of available-for-sale investments by type of security was as follows: June 30, 2016 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Commercial Paper $ 45,413 $ 58 $ — $ 45,471 Certificates of Deposit $ 13,271 $ — — $ 13,271 Corporate Bonds 84,736 27 (35 ) 84,728 Government Securities 51,088 16 (3 ) 51,101 Treasury Bonds 18,029 21 — 18,050 $ 212,537 $ 122 $ (38 ) $ 212,621 December 31, 2015 Amortized Cost Gross Unrealized Gain Gross Unrealized Loss Fair Value Investments: Commercial Paper $ 64,733 $ 87 $ — $ 64,820 Corporate Bonds 46,538 — (48 ) 46,490 Government Securities 15,823 — (4 ) 15,819 Treasury Bonds 4,022 — (2 ) 4,020 $ 131,116 $ 87 $ (54 ) $ 131,149

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2016
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following: June 30, 2016 December 31, 2015 Laboratory equipment $ 6,804 $ 4,370 Computer equipment 971 408 Furniture and office equipment 788 285 Leasehold improvements 9,965 1,856 Construction in progress 10,692 1,843 29,220 8,762 Less: Accumulated depreciation and amortization (2,235 ) (1,011 ) $ 26,985 $ 7,751

Accrued Expenses and Other Cu25

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2016
Payables And Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: June 30, 2016 December 31, 2015 Development and manufacturing costs $ 3,258 $ 1,436 Payroll and payroll-related costs 2,375 2,756 Professional fees 449 184 Facility 4,662 1,053 Other 121 94 $ 10,865 $ 5,523

Preferred Stock Warrant Liabi26

Preferred Stock Warrant Liability (Tables)	6 Months Ended
	Jun. 30, 2016
Class Of Stock Disclosures [Abstract]
Summary of Assumptions and Inputs Used in Determining Fair Value of Preferred Stock Warrant Liability Valued Using Black-Scholes Option-Pricing Model	The following assumptions and inputs were used in determining the fair value of the preferred stock warrant liability valued using the Black-Scholes option-pricing model: Six Months Ended June 30, 2015 Risk-free interest rate 2.40 % Expected term (in years) 8.2 Expected volatility 91.2 % Expected dividend yield 0 % Fair value of Series A-2 convertible preferred stock $ 17.26

Stockholders_ Equity Common S27

Stockholders’ Equity Common Stock (Tables)	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity since December 31, 2015: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding as of December 31, 2015 5,026,246 $ 8.01 8.70 $ 136,945 Granted 1,418,625 28.05 Exercised (777,138 ) 1.21 Forfeited (55,344 ) 13.48 Outstanding as of June 30, 2016 5,612,389 $ 13.96 8.41 $ 88,441 Options exercisable as of June 30, 2016 1,793,436 $ 6.00 7.52 $ 41,438 Options vested and expected to vest as of June 30, 2016 5,491,857 $ 13.85 8.40 $ 87,103
Summary of Stock Based Compensation Expense	The Company recorded stock-based compensation expense related to stock options and restricted common stock in the following expense categories of its consolidated statements of operations and comprehensive loss: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Research and development expenses $ 2,896 $ 1,891 $ 5,082 $ 2,514 General and administrative expenses 1,821 1,182 3,539 1,886 $ 4,717 $ 3,073 $ 8,621 $ 4,400

Nature of the Business and Ba28

Nature of the Business and Basis of Presentation - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Entity incorporated year	Oct. 31, 2010
Entity incorporated state name	State of Delaware

Summary of Significant Accoun29

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended	6 Months Ended
	Feb. 29, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounting Policies [Line Items]
Fair value of liabilities on recurring basis		$ 0	$ 0
Fair value, assets transfers from Level 1 to Level 2 measurement		0
Fair value, assets transfers from Level 2 to Level 1 measurement		0
Fair Value, assets transfers into (out of) Level 3 measurement		0
Nestlé Health Science [Member]
Accounting Policies [Line Items]
Upfront non-refundable payment	$ 120,000,000	$ 120,000,000

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Assets:
Cash Equivalents		$ 17,330	$ 23,125
Repurchase Agreements		5,500	20,000
Investments:
Total assets		235,451	174,274
Fair Value, Inputs, Level 2 [Member]
Assets:
Cash Equivalents		9,971	11,952
Repurchase Agreements		5,500	20,000
Investments:
Total assets		228,092	163,101
Not Subject to Leveling [Member]
Assets:
Cash Equivalents	[1]	7,359	11,173
Investments:
Total assets	[1]	7,359	11,173
Commercial Paper [Member]
Investments:
Investments		45,471	64,820
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Investments:
Investments		45,471	64,820
Certificates of Deposit [Member]
Investments:
Investments		13,271
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Investments:
Investments		13,271
Corporate Bonds [Member]
Investments:
Investments		84,728	46,490
Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Investments:
Investments		84,728	46,490
Government Securities [Member]
Investments:
Investments		51,101	15,819
Government Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investments:
Investments		51,101	15,819
Treasury Bonds [Member]
Investments:
Investments		18,050	4,020
Treasury Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Investments:
Investments		$ 18,050	$ 4,020
[1]	Certain cash equivalents and investments that are valued using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.

Summary of Significant Accoun31

Summary of Significant Accounting Policies - Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	5,612,389	4,902,998
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	5,612,389	4,809,621
Unvested Restricted Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share		1,250
Warrants for the Purchase of Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share		92,127

Investments - Schedule of Fair

Investments - Schedule of Fair Value of Available-for-Sale Investments by Type of Security (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 212,537	$ 131,116
Gross Unrealized Gain	122	87
Gross Unrealized Loss	(38)	(54)
Fair Value	212,621	131,149
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	45,413	64,733
Gross Unrealized Gain	58	87
Fair Value	45,471	64,820
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	84,736	46,538
Gross Unrealized Gain	27
Gross Unrealized Loss	(35)	(48)
Fair Value	84,728	46,490
Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	51,088	15,823
Gross Unrealized Gain	16
Gross Unrealized Loss	(3)	(4)
Fair Value	51,101	15,819
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	13,271
Fair Value	13,271
Treasury Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	18,029	4,022
Gross Unrealized Gain	21
Gross Unrealized Loss		(2)
Fair Value	$ 18,050	$ 4,020

Investments - Additional Inform

Investments - Additional Information (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Investment [Line Items]
Maximum maturity days for cash equivalents	90 days
Corporate Bonds, Commercial Paper, Government Securities and Treasury Bonds [Member]
Investment [Line Items]
Remaining maturity period of investments		12 months

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 29,220	$ 8,762
Less: Accumulated depreciation and amortization	(2,235)	(1,011)
Property and equipment, net	26,985	7,751
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,804	4,370
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	971	408
Furniture and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	788	285
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	9,965	1,856
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 10,692	$ 1,843

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 874	$ 119	$ 1,260	$ 212

Accrued Expenses and Other Cu36

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Development and manufacturing costs	$ 3,258	$ 1,436
Payroll and payroll-related costs	2,375	2,756
Professional fees	449	184
Facility	4,662	1,053
Other	121	94
Total Accrued Expenses and Other Current Liabilities	$ 10,865	$ 5,523

Preferred Stock Warrant Liabi37

Preferred Stock Warrant Liability - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
	Sep. 30, 2013	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jul. 01, 2015	Jun. 26, 2015
Class of Stock [Line Items]
Fair value of warrant issuance				$ 0	$ 0
Loss from revaluation of preferred stock warrant liability		$ 220,000	$ 7,000
Common Stock [Member] | Initial Public Offering ("IPO") [Member]
Class of Stock [Line Items]
Public offering price per share						$ 18	$ 18
Series A-2 Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Warrants issued to purchase of stock	92,127
Warrants exercise price per share	$ 1.78
Class of warrant or right, contractual term	10 years
Fair value of warrant issuance	$ 156,000	$ 17,260	$ 17,260

Preferred Stock Warrant Liabi38

Preferred Stock Warrant Liability - Summary of Assumptions and Inputs Used in Determining Fair Value of Preferred Stock Warrant Liability Valued Using Black-Scholes Option-Pricing Model (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	2.40%
Expected term (in years)	8 years 2 months 12 days
Expected volatility	91.20%
Expected dividend yield	0.00%
Fair value of Series A-2 convertible preferred stock		$ 0	$ 0
Series A-2 Convertible Preferred Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of Series A-2 convertible preferred stock	$ 17,260			$ 156,000

Preferred Stock - Additional In

Preferred Stock - Additional Information (Detail) - $ / shares	Jun. 30, 2016	Dec. 31, 2015	Jul. 01, 2015
Equity [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, par value	$ 0.001	$ 0.001	$ 0.001

Stockholders' Equity Common Sto

Stockholders' Equity Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 02, 2015	Jun. 26, 2015	Jun. 30, 2016	Dec. 31, 2015	Jul. 01, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized			200,000,000	200,000,000		38,000,000
Common stock, par value			$ 0.001	$ 0.001		$ 0.001
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued and sold	8,545,138
Net proceeds from issuance of common stock from IPO after deducting underwriting discounts and commissions	$ 139,267
Estimated stock offering expenses	$ 3,748
Conversion of redeemable convertible preferred stock into common stock		22,866,987
Initial Public Offering ("IPO") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized					200,000,000
Common stock, par value					$ 0.001
Initial Public Offering ("IPO") [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Public offering price per share		$ 18			$ 18
Over-Allotment Option [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued and sold	1,114,583

Stockholders' Equity Common S41

Stockholders' Equity Common Stock - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Equity [Abstract]
Number of shares, Beginning Balance	5,026,246
Number of shares, Granted	1,418,625
Number of shares, Exercised	(777,138)
Number of shares, Forfeited	(55,344)
Number of shares, Ending Balance	5,612,389	5,026,246
Number of shares, Options exercisable	1,793,436
Number of shares, Options vested and expected to vest	5,491,857
Weighted Average Exercise Price, Beginning Balance	$ 8.01
Weighted Average Exercise Price, Granted	28.05
Weighted Average Exercise Price, Exercised	1.21
Weighted Average Exercise Price, Forfeited	13.48
Weighted Average Exercise Price, Ending Balance	13.96	$ 8.01
Weighted Average Exercise Price, Options exercisable	6
Weighted Average Exercise Price, Options vested and expected to vest	$ 13.85
Weighted Average Remaining Contractual Term, Outstanding	8 years 4 months 28 days	8 years 8 months 12 days
Weighted Average Remaining Contractual Term, Options exercisable	7 years 6 months 7 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	8 years 4 months 24 days
Aggregate Intrinsic Value	$ 88,441	$ 136,945
Aggregate Intrinsic Value, Options exercisable	41,438
Aggregate Intrinsic Value, Options vested and expected to vest	$ 87,103

Stockholders' Equity Common S42

Stockholders' Equity Common Stock - Stock Options - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value of stock options	$ 20.64		$ 19.87
Expense for stock options	$ 4,717	$ 3,073	$ 8,621	$ 4,400
Stock Option [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option exercisable	0		0
Performance-Based stock options granted	60,000
Expense for stock options	$ 212
Grant date fair value of options	$ 3.92

Stockholders' Equity Common S43

Stockholders' Equity Common Stock - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,717	$ 3,073	$ 8,621	$ 4,400
Research and development expenses [Member] | Stock Options and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,896	1,891	5,082	2,514
General and administrative expenses [Member] | Stock Options and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 1,821	$ 1,182	$ 3,539	$ 1,886

Collaboration Revenue - Additio

Collaboration Revenue - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	6 Months Ended
	Feb. 29, 2016	Jan. 31, 2016	Jun. 30, 2016	Jun. 30, 2016
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Period of performance identifiable deliverables		10 years
Collaboration revenue - related party			$ 3,004	$ 5,714
Deferred revenue				114,383
Phase 3 Clinical Trials [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of costs owned under clinical trial programs		67.00%
Nestlé Health Science [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment	$ 120,000			120,000
Development milestone payments		$ 295,000
Regulatory payments		365,000
Sales based milestones		$ 1,125,000
Percentage of costs remaining under clinical trial programs		33.00%
Reimbursement of development services				97
Collaboration revenue - related party			$ 3,004	5,714
Deferred revenue				$ 114,383

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0
Accrued interest or tax penalties	$ 0		$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Nov. 11, 2015USD ($)ft²	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Other Commitments [Line Items]
Operating lease agreement expiration date				Jun. 30, 2016
Operating lease termination write off of deferred rent benefit				$ 136,000
Outstanding security deposit		$ 119,000		$ 119,000
Operating lease early termination notice period for security deposit				90 days
Lease incentive obligation		9,119,000		$ 9,119,000		$ 586,000
Indemnification Agreement [Member]
Other Commitments [Line Items]
Indemnification obligations accrued		0		0		$ 0
Office and Laboratory Space [Member]
Other Commitments [Line Items]
Rental expense related to office and laboratory space		787,000	$ 354,000	$ 1,180,000	$ 540,000
BMR Sidney Research Campus LLC [Member]
Other Commitments [Line Items]
Non-cancelable property lease, description				On November 11, 2015, the Company entered into a non-cancelable property lease with BMR-Sidney Research Campus LLC (“BMR”) for 83,396 square feet of office, laboratory and pilot manufacturing space at 200 Sidney Street, Cambridge, Massachusetts. The lease term commenced in March 2016 and ends in November 2023. The Company has the option to extend the lease twice, each for a five-year period. The Company moved its corporate headquarters to this location in April
Square feet of property subject to non-cancelable lease | ft²	83,396
Lease commencement period	2016-03
Lease expiration period	2023-11
Cost of tenant improvements	$ 12,509,000
Lease incentive obligation		$ 9,119,000		$ 9,119,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Collaboration revenue - related party	$ 3,004,000		$ 5,714,000
Flagship Ventures Management INC [Member] | Services Agreement [Member]
Related Party Transaction [Line Items]
Payments under agreements with related party	1,000	$ 131,000	17,000	$ 249,000
Due to related party	0		0		$ 0
Nestlé Health Science [Member]
Related Party Transaction [Line Items]
Payments under agreements with related party	0		0
Due to related party	97,000		97,000
Collaboration revenue - related party	3,004,000		5,714,000
Deferred revenue	114,383,000		114,383,000
Due from related party for the reimbursement of development costs	$ 97,000		$ 97,000

401(k) Savings Plan - Additiona

401(k) Savings Plan - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 01, 2016	Jun. 30, 2016	Jun. 30, 2016
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Employer match of employee contributions	50.00%
Employee deferral subject to employer match	6.00%
Employer contribution expenses		$ 188	$ 188

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ in Thousands	Jun. 30, 2016USD ($)
Phase 3 Clinical Trials [Member]
Subsequent Event [Line Items]
Prepaid expense	$ 690