Paratek Pharmaceuticals (PRTK) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	PRTK
Entity Registrant Name	PARATEK PHARMACEUTICALS, INC.
Entity Central Index Key	1,178,711
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		31,596,149

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 49,273	$ 35,416
Available-for-sale securities	135,051	116,307
Restricted cash	229	162
Accounts receivable	50	5,041
Other receivable	785	848
Prepaid and other current assets	2,840	2,712
Total current assets	188,228	160,486
Restricted cash	250	250
Fixed assets, net	1,583	1,711
Intangible assets, net	139	142
Goodwill	829	829
Other long-term assets	263	280
Total assets	191,292	163,698
Current liabilities
Accounts payable	3,756	3,555
Other accrued expenses	6,938	8,270
Accrued contract manufacturing costs	5,064	4,964
Current portion of long-term debt	7,607
Total current liabilities	23,365	16,789
Long-term debt	51,684	59,186
Contingent obligations	56	71
Other liabilities	5,420	5,174
Total liabilities	80,525	81,220
Commitments and contingencies (Note 15)
Stockholders’ equity
Undesignated preferred stock: $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value; 100,000,000 shares authorized; 31,443,149 and 27,941,015 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	31	28
Additional paid-in capital	608,776	552,720
Accumulated other comprehensive loss	(180)	(158)
Accumulated deficit	(497,860)	(470,112)
Total stockholders’ equity	110,767	82,478
Total liabilities and stockholders’ equity	$ 191,292	$ 163,698

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (unaudited) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Undesignated preferred stock, par value	$ 0.001	$ 0.001
Undesignated preferred stock, shares authorized	5,000,000	5,000,000
Undesignated preferred stock, shares issued	0	0
Undesignated preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	31,443,149	27,941,015
Common stock, shares outstanding	31,443,149	27,941,015

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
License and royalty revenue	$ 10	$ 18
Operating expenses:
Research and development	14,864	18,657
General and administrative	11,873	8,363
Changes in fair value of contingent consideration	(15)	(231)
Total operating expenses	26,722	26,789
Loss from operations	(26,712)	(26,771)
Other income and expenses:
Interest expense	(1,507)	(1,132)
Interest income	475	240
Other loss, net	(6)	(7)
Net loss	(27,750)	(27,670)
Other comprehensive income:
Unrealized loss on available-for-sale securities, net of tax	(21)	(38)
Comprehensive loss	$ (27,771)	$ (27,708)
Net loss per share - basic and diluted	$ (0.91)	$ (1.14)
Weighted average common shares outstanding Basic and diluted	30,566,694	24,196,158

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Cash Flows [Abstract]
Net loss	$ (27,750)	$ (27,670)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	187	301
Stock-based compensation expense	4,367	4,044
Noncash interest expense	439	293
Changes in fair value of contingent consideration	(15)	(231)
Changes in operating assets and liabilities
Accounts receivable and other current assets	4,985	420
Purchase of prepaid interest - marketable securities	(77)
Accounts payable and accrued expenses	(1,452)	(2,439)
Other liabilities and other assets	264	355
Net cash used in operating activities	(19,052)	(24,927)
Investing activities
Purchase of fixed assets, net	(24)	(897)
Purchase of marketable securities	(49,692)	(27,665)
Proceeds from maturities of marketable securities	31,000	25,000
Net cash used in investing activities	(18,716)	(3,562)
Financing activities
Proceeds from exercise of stock options	176	22
Proceeds from sale of common stock	51,516	36,859
Net cash provided by financing activities	51,692	36,881
Net decrease in cash, cash equivalents and restricted cash	13,924	8,392
Cash, cash equivalents and restricted cash at beginning of period	35,828	54,029
Cash, cash equivalents and restricted cash at end of period	49,752	62,421
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for interest	$ 1,077	737
Purchases of fixed assets in accrued expenses		$ 198

Description of the Business

Description of the Business	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Description of the Business	1. Description of the business Paratek Pharmaceuticals, Inc., or the Company or Paratek, is a Delaware corporation with its corporate office in Boston, Massachusetts and an office in King of Prussia, Pennsylvania. The Company is a clinical stage biopharmaceutical company focused on the development and commercialization of innovative therapeutics based upon tetracycline chemistry. The Company has used its expertise in biology and tetracycline chemistry to create chemically diverse and biologically distinct small molecules derived from the minocycline core structure. The Company’s two lead product candidates are the antibacterials omadacycline and sarecycline. Prior to October 30, 2014, the name of the Company was Transcept Pharmaceuticals, Inc., or Transcept. On October 30, 2014, Transcept completed a business combination with privately-held Paratek Pharmaceuticals, Inc., or Old Paratek, in accordance with the terms of the Agreement and Plan of Merger and Reorganization, dated as of June 30, 2014, by and among Transcept, Tigris Merger Sub, Inc., or Merger Sub, Tigris Acquisition Sub, LLC, or Merger LLC, and Old Paratek, or the Merger Agreement, pursuant to which Merger Sub merged with and into Old Paratek, with Old Paratek surviving as a wholly-owned subsidiary of Transcept, followed by the merger of Old Paratek with and into Merger LLC, with Merger LLC surviving as a wholly-owned subsidiary of Transcept (the Company refers to these mergers together as the Merger). Immediately following the Merger, Transcept changed its name to “Paratek Pharmaceuticals, Inc.”, and Merger LLC changed its name to “Paratek Pharma, LLC.” Following the completion of the Merger, the business conducted by Old Paratek became primarily the business conducted by Paratek. The Company has incurred significant losses since its inception in 1996. The Company has generated an accumulated deficit of $497.9 million through March 31, 2018 and will require substantial additional funding in connection with the Company’s continuing operations to support commercial activities associated with its lead product candidate, omadacycline. Based upon the Company’s current operating plan, the Company anticipates that its existing cash, cash equivalents and marketable securities of $184.3 million as of March 31, 2018, together with the $158.8 in net proceeds received from its April 2018 convertible notes offering, will enable the Company to fund operating expenses and capital expenditure requirements through at least the next twelve months from the filing date of this Quarterly Report on Form 10-Q. The Company expects to finance future cash needs primarily through a combination of public or private equity offerings, debt or other structured financings, strategic collaborations and grant funding. The Company is subject to risks common to companies in the biopharmaceutical industry, including, but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain additional financing to fund the future development of the Company’s product candidates, the need to obtain compliant product from third party manufacturers, the need to obtain marketing approval for the Company’s product candidates, the need to successfully commercialize and gain market acceptance of product candidates, the risks of manufacturing product with an external supply chain, dependence on key personnel, and compliance with government regulations as well as those risks discussed in the “ Risk Factors ” section of the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the Securities and Exchange Commission, or the SEC, on March 6, 2018, in the “Risk Factors” section of this Quarterly Report on Form 10-Q and elsewhere in this Quarterly Report on Form 10-Q.

Summary of Significant Accounti

Summary of Significant Accounting Policies and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Basis of Presentation	2. Summary of Significant Accounting Policies and Basis of Presentation 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 consolidated financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 6, 2018. Statement of Cash Flows On January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230) Restricted Cash , or ASU 2016-18. The Company’s restricted cash is now included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the Company’s condensed consolidated statement of cash flows. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated statement of cash flows that sum to the total of the same such amounts shown in the condensed consolidated statement of cash flows. March 31, 2018 December 31, 2017 March 31, 2017 Cash and cash equivalents $ 49,273 $ 35,416 $ 62,044 Short-term restricted cash 229 162 127 Long-term restricted cash 250 250 250 Total cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows $ 49,752 $ 35,828 $ 62,421 Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers The Company enters into collaboration agreements for research, development, manufacturing and commercial services that are within the scope of ASC 606, under which it licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period. The contracts into which the Company enters generally do not include significant financing components. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the transaction price under step (iii) above and (b) the timing of revenue recognition, including the appropriate measure of progress in step (v) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties, should be included in the transaction price, as described further below. The transaction price is allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. If a milestone or other variable consideration relates specifically to the Company’s efforts to satisfy a single performance obligation or to a specific outcome from satisfying the performance obligation, the Company generally allocates the milestone amount entirely to that performance obligation once it is probable that a significant revenue reversal would not occur. Amounts received prior to revenue recognition are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Licenses of intellectual property In assessing whether a license is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a license for its intended purpose without the receipt of the remaining promise(s), whether the value of the license is dependent on the unsatisfied promise(s), whether there are other vendors that could provide the remaining promise(s), and whether it is separately identifiable from the remaining promise(s). For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Customer options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent or include a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the probability that the customer will exercise. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone payments At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant reversal of cumulative revenue would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Contract costs The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer. Impact of adoption As a result of adopting ASC 606 on January 1, 2018, there are no significant changes to the revenue recognition pattern for any of the Company’s license and collaboration agreements. For further discussion of the adoption of this standard, and for a discussion of accounting for collaboration revenue, see Note 8, License and Collaboration Agreements There have been no other material changes in the Company’s significant accounting policies during the three months ended March 31, 2018. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles of the United States of America, or U.S. GAAP, as found in the ASC and ASU of the Financial Accounting Standards Board, or FASB, and pursuant to the rules and regulations of the SEC. The accompanying condensed consolidated financial statements are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements as of and for the year ended December 31, 2017, except as described above related to the adoption of ASU 2016-15 and ASC 606 and, in the opinion of management, reflect all normal recurring adjustments necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the interim period ended March 31, 2018. Beginning in the three months ended March 31, 2018, the Company presented “accrued contract manufacturing costs” as a separate line item on its condensed consolidated balance sheet. As such, the Company reclassified the December 31, 2017 accrued manufacturing balance of $5.0 million, from “other accrued expenses” into “accrued contract manufacturing costs”. The Company also reclassified the balance of “accrued contract research” of $2.4 million as of December 31, 2017, previously presented as a separate line within the Company’s consolidated balance sheet, into “other accrued expenses” on the condensed consolidated balance sheet as of March 31, 2018. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2018. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2017, and notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 6, 2018. Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the results of operations of Paratek Pharmaceuticals, Inc. and its wholly-owned subsidiaries, Paratek Pharma, LLC, Paratek Securities Corporation, Transcept Pharma, Inc., Paratek UK, Ltd, Paratek Bermuda Ltd., and Paratek Ireland Limited. All significant intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of the accompanying unaudited condensed consolidated financial statements, in conformity with U.S. GAAP, requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, and expenses and the disclosure of contingent liabilities in the Company’s financial statements. On an ongoing basis, the Company evaluates its estimates and judgments, including those related to, Segment and Geographic Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment.

Cash and Cash Equivalents and M

Cash and Cash Equivalents and Marketable Securities	3 Months Ended
	Mar. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash and Cash Equivalents and Marketable Securities	3. Cash and Cash Equivalents and Marketable Securities The following is a summary of available-for-sale securities as of March 31, 2018 and December 31, 2017 (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value March 31, 2018 U.S. treasury securities $ 134,431 $ — $ (180 ) $ 134,251 Government agencies 800 — — 800 Total $ 135,231 $ — $ (180 ) $ 135,051 December 31, 2017 U.S. treasury securities $ 114,666 $ — $ (158 ) $ 114,508 Government agencies 1,799 — — 1,799 Total $ 116,465 $ — $ (158 ) $ 116,307 No available-for-sale securities held as of March 31, 2018 and December 31, 2017 had remaining maturities greater than one year.

Restricted Cash

Restricted Cash	3 Months Ended
	Mar. 31, 2018
Restricted Cash And Investments [Abstract]
Restricted Cash	4. Restricted Cash Short-term restricted cash As of March 31, 2018 and December 31, 2017, restricted cash of $0.2 million represents royalty income received but not yet paid to former Transcept stockholders as part of the royalty sharing agreement, or the Royalty Sharing Agreement, executed by the Company on October 28, 2016 with the Special Committee of the Company’s Board of Directors, or the Special Committee, a committee established in connection with the Merger. See Note 11, Fair Value Measurements Long-term restricted cash The Company leases its Boston, Massachusetts office space under a non-cancelable operating lease. Refer to Note 15, Commitments and Contingencies In accordance with the lease, the Company has a cash-collateralized irrevocable standby letter of credit in the amount of $0.3 million as of March 31, 2018 and December 31, 2017, naming the landlord as beneficiary.

Fixed Assets

Fixed Assets	3 Months Ended
	Mar. 31, 2018
Property Plant And Equipment [Abstract]
Fixed Assets	5. Fixed Assets Fixed assets, net, consists of the following (in thousands): March 31, 2018 December 31, 2017 Office equipment $ 866 $ 866 Computer equipment 412 412 Computer software 787 787 Leasehold improvements 860 860 Construction-in-process 23 — Gross fixed assets 2,948 2,925 Less: Accumulated depreciation and amortization (1,365 ) (1,214 ) Net fixed assets $ 1,583 $ 1,711

Intangible Assets, Net

Intangible Assets, Net	3 Months Ended
	Mar. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	6. Intangible Assets, Net Intangible assets consist of the following (in thousands): March 31, 2018 December 31, 2017 Intermezzo product rights $ 142 $ 142 TO-2070 asset 170 170 Gross intangible assets 312 312 Less: Accumulated amortization (173 ) (170 ) Net intangible assets $ 139 $ 142 Intermezzo product rights and the TO-2070 license rights were acquired through the Merger. Refer to Note 8, License and Collaboration Agreements,

Net Loss Per Share Available to

Net Loss Per Share Available to Common Stockholders	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share Available to Common Stockholders	7. Net Loss Per Share Available to Common Stockholders Basic net loss per share available to common stockholders is calculated by dividing the net loss available to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share available to common stockholders is computed by dividing the net loss available to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method or the if-converted method, as applicable. For purposes of this calculation, stock options, restricted stock units, or RSUs, and warrants to purchase common stock are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share available to common stockholders when their effect is dilutive. The following outstanding shares subject to stock options, RSUs and warrants to purchase common stock were antidilutive due to a net loss in the periods presented and, therefore, were excluded from the dilutive securities computation as of the three months ended March 31, 2018 and 2017 as indicated below: March 31, 2018 2017 Excluded potentially dilutive securities (1) Shares subject to outstanding options to purchase common stock 3,690,934 3,452,076 Unvested restricted stock units 2,169,974 955,503 Shares subject to warrants to purchase common stock 84,828 79,454 Shares issuable under employee 2009 stock purchase plan 36,539 36,539 Totals 5,982,275 4,523,572 (1) The number of shares is based on the maximum number of shares issuable on exercise or conversion of the related securities as of March 31, 2018. Such amounts have not been adjusted for the treasury stock method or weighted average outstanding calculations as required if the securities were dilutive.

License and Collaboration Agree

License and Collaboration Agreements	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
License and Collaboration Agreements	8. License and Collaboration Agreements Zai Lab (Shanghai) Co., Ltd. On April 21, 2017, Paratek Bermuda Ltd., a wholly-owned subsidiary of Paratek Pharmaceuticals, Inc., and Zai Lab (Shanghai) Co., Ltd., or Zai, entered into a License and Collaboration Agreement, or the Zai Collaboration Agreement. Under the terms of the Zai Collaboration Agreement, Paratek Bermuda Ltd. granted Zai an exclusive license to develop, manufacture and commercialize omadacycline, or the licensed product, in the People’s Republic of China, Hong Kong, Macau and Taiwan, or the territory, for all human therapeutic and preventative uses other than biodefense. Zai will be responsible for the development, manufacturing and commercialization of the licensed product in the territory, at its sole cost with certain assistance from Paratek Bermuda Ltd. Under the terms of the Zai Collaboration Agreement, Paratek Bermuda Ltd. earned an upfront cash payment of $7.5 million, before taxes, and is eligible to receive up to $14.0 million in potential regulatory milestone payments and $40.5 million in potential commercial milestone payments, the next being $5.0 million upon approval by the U.S. Food & Drug Administration, or the FDA, of a New Drug Application, or NDA, submission in the CABP indication. Zai will also pay Paratek Bermuda Ltd. tiered royalties at a low double digit to mid-teen percent on net sales of the licensed product in the territory. The Zai Collaboration Agreement will continue, on a region-by-region basis, until the expiration of and payment by Zai of all Zai’s payment obligations, which is until the later of: (i) the abandonment, expiry or final determination of invalidity of the last valid claim within the Paratek patents that covers the licensed product in the region in the territory in the manner that Zai or its affiliates or sublicensees exploit the licensed product or intend for the licensed product to be exploited; or (ii) the eleventh anniversary of the first commercial sale of such licensed product in such region. The Company evaluated the Zai Collaboration Agreement under ASC 606 “Revenue from Contracts with Customers.” The Company determined that there were six material promises under the Zai Collaboration Agreement: (i) an exclusive license to develop, manufacture and commercialize omadacycline in the territory, (ii) the initial technology transfer (ii) a transfer of certain materials and materials know-how, (iv) optional manufacturing services, (v) optional regulatory support and (vi) optional commercialization support. The Company determined that the exclusive license and initial technology transfer were not distinct from one another, as the license has limited value without the transfer of the Company’s technology; which will allow . Without the technology transfer, Zai would incur additional costs to recreate the Company’s know-how. Therefore, the license and initial technology transfer are combined as a single performance obligation. The transfer of materials is a single distinct performance obligation. The Company evaluated the option rights for manufacturing services, regulatory support and commercialization support to determine whether they represent or include material rights to Zai and concluded that the options were not issued at a discount, and therefore do not represent material rights. As such, they are not considered performance obligations at the outset of the arrangement. Based on these assessments, the Company determined that two performance obligations existed at the outset of the Zai Collaboration Agreement: (i) the exclusive license combined with the initial technology transfer and (ii) the transfer of certain materials. The Company determined that the upfront payment of $7.5 million constituted the entirety of the consideration to be included in the transaction price as of the outset of the Zai Collaboration Agreement. Future potential milestone payments were excluded from the transaction price as they are fully constrained as the risk of significant reversal has not yet been resolved. The Company satisfied both performance obligations and recognized the upfront payment of $7.5 million as revenue in the three months ended June 30, 2017. The Company did not recognize revenue under the Zai Collaboration Agreement in the three months ended March 31, 2018 or March 31, 2017. There was no deferred revenue as of March 31, 2018. Allergan plc In July 2007, the Company and Warner Chilcott Company, Inc. (now part of Allergan plc, or Allergan), entered into a collaborative research and license agreement, or the Allergan Collaboration Agreement, under which the Company granted Allergan an exclusive license to research, develop and commercialize tetracycline products for use in the United States for the treatment of acne and rosacea. Since Allergan did not exercise its development option with respect to the treatment of rosacea prior to initiation of a Phase 3 trial for the product, the license grant to Allergan converted to a non-exclusive license for the treatment of rosacea as of December 2014. Under the terms of the Allergan Collaboration Agreement, the Company and Allergan are responsible for, and are obligated to use, commercially reasonable efforts to conduct specified development activities for the treatment of acne and, if requested by Allergan, the Company may conduct certain additional development activities to the extent the Company determines in good faith that the Company has the necessary resources available for such activities. Allergan has agreed to reimburse the Company for its costs and expenses, including third-party costs, incurred in conducting any such development activities. Under the terms of the Allergan Collaboration Agreement, Allergan is responsible for and is obligated to use commercially reasonable efforts to develop and commercialize tetracycline compounds that are specified in the agreement for the treatment of acne. The Company has agreed during the term of the Allergan Collaboration Agreement not to directly or indirectly develop or commercialize any tetracycline compounds in the United States for the treatment of acne and rosacea, and Allergan has agreed during the term of the Allergan Collaboration Agreement not to directly or indirectly develop or commercialize any tetracycline compound included as part of the agreement for any use other than as provided in the agreement. The Allergan Collaboration Agreement contains two performance obligations: (i) an exclusive license to research, develop and commercialize tetracycline products for use in the United States for the treatment of acne and rosacea and (ii) research and development services. The performance obligation to deliver the license was satisfied upon execution of the Allergan Collaboration Agreement in July 2007. All research and development services were completed by December 2010. The options provided to Allergan for additional development services do not provide Allergan with a material right as these services will not be provided at a significant or incremental discount. As such, the option services are not performance obligations. The Company received an upfront fee in the amount of $4.0 million upon the execution of the Allergan Collaboration Agreement, $1.0 million upon filing of an Investigational New Drug Application in 2010, $2.5 million upon initiation of Phase 2 trials in 2012 and $4.0 million upon initiation of Phase 3 trials associated with the Allergan Collaboration Agreement in December 2014. In December 2017, the FDA’s acceptance of Allergan’s NDA for sarecycline, or Seysara™ was received, triggering the next eligible milestone payment of $5.0 million earned upon acceptance of an NDA for a product licensed under the Allergan Collaboration Agreement. As the performance obligation to deliver the license was satisfied in 2007 and research and development services completed by December 2010, all subsequent milestone payments are recognized as revenue when the risk of significant reversal is resolved, generally when the milestone event occurs. Therefore, the $5.0 million milestone payment was recognized in December 2017 and subsequently collected in the first quarter of 2018. Allergan may be required, if the Company receives FDA approval, to pay the Company a future milestone payment of $12.0 million upon receipt of regulatory approval from the FDA. Allergan is also obligated to pay the Company tiered royalties, ranging from the mid-single digits to the low double digits, based on net sales of tetracycline compounds developed under the Allergan Collaboration Agreement, with a standard royalty reduction post patent expiration for such product for the remainder of the royalty term. Allergan’s obligation to pay the Company royalties for each tetracycline compound it commercializes under the Allergan Collaboration Agreement expires on the later of the expiration of the last to expire patent that covers the tetracycline compound in the United States and the date on which generic drugs that compete with the tetracycline compound reach a certain threshold market share in the United States. The Company has not received any amounts or recognized any revenue under this arrangement in for the three months ended March 31, 2018 or March 31, 2017. The future potential milestone payment was excluded from the transaction price as it is fully constrained as the risk of significant reversal has not yet been resolved. Royalty payments would be recognized when the sale occurs. Purdue Pharma L.P. In July 2009, the Company and Purdue Pharma L.P., or Purdue Pharma, entered into a license and collaboration agreement, or the Purdue Collaboration Agreement, which grants an exclusive license to Purdue Pharma to commercialize Intermezzo in the United States and pursuant to which: • Purdue Pharma paid the Company a $25.0 million non-refundable license fee in August 2009, and non-refundable intellectual property milestone payments of $10.0 million in each of December 2011 and August 2012; • The Company transferred the Intermezzo NDA to Purdue Pharma, and Purdue Pharma is obligated to assume the expense associated with maintaining the NDA and further development of Intermezzo in the United States, including any expense associated with post-approval studies; • Purdue Pharma is obligated to commercialize Intermezzo in the United States at its expense using commercially reasonable efforts; • Purdue Pharma is obligated to pay the Company tiered base royalties on net sales of Intermezzo in the United States ranging from the mid-teens up to the mid-20% level, with each such royalty tiers subject to an increase by a percentage in the low single digits upon a specified anniversary of regulatory approval of Intermezzo. The base royalty is tiered depending upon the achievement of certain fixed net sales thresholds by Purdue Pharma, which net sales levels reset each year for the purpose of calculating the royalty. The royalty tiers are subject to reductions upon generic entry and patent expiration. Purdue Pharma is obligated to pay royalties until the later of 15 years from the date of first commercial sale in the United States or the expiration of patent claims related to Intermezzo; and • Purdue Pharma is obligated to pay the Company up to an additional $70.0 million upon the achievement of certain net sales targets for Intermezzo in the United States. The Purdue Collaboration Agreement expires on the expiration of Purdue Pharma’s royalty obligations. Purdue Pharma has the right to terminate the Purdue Collaboration Agreement at any time upon advance notice of 180 days. The Purdue Collaboration Agreement is also subject to termination by Purdue Pharma in the event of FDA or governmental action that materially impairs Purdue Pharma’s ability to commercialize Intermezzo or the occurrence of a serious event with respect to the safety of Intermezzo. The Purdue Collaboration Agreement may be terminated by the Company upon Purdue Pharma commencing an action that challenges the validity of Intermezzo related patents or if Purdue Pharma is excluded from participation in federal healthcare programs. The Purdue Collaboration Agreement may be terminated by either party in the event of a material breach by or insolvency of the other party. The Company also granted Purdue Pharma and an associated company the right to negotiate for the commercialization of Intermezzo in Mexico in 2013 but retained the rights to commercialize Intermezzo in the rest of the world. During the first quarter of 2014, Purdue Pharma discontinued use of the Purdue Pharma sales force to actively market Intermezzo to healthcare professionals. In October 2014, the Company announced that its Board of Directors had approved a special dividend of, among other things, the right to receive, on a pro rata basis, 100% of any royalty income received by the Company pursuant to the Purdue Collaboration Agreement and 90% of any cash proceeds from a sale or disposition of Intermezzo, less fees and expenses incurred in connection with such activity, to the extent that either occurred prior to the second anniversary of the closing date of the Merger. On October 28, 2016, in satisfaction of the Company’s payment obligation of the proceeds of sale or disposition of the Intermezzo assets to the former Transcept stockholders under the Merger Agreement, the Company executed the Royalty Sharing Agreement pursuant to which the Company agreed to pay to the former Transcept stockholders fifty percent of all royalty income received by the Company pursuant to the Purdue Collaboration Agreement, net of all costs, fees and expenses incurred by the Company in connection with the Purdue Collaboration Agreement, related agreements, the Intermezzo product and the administration of the royalty income to the former Transcept stockholders. As of December 2011, the Company completed all obligations under the Purdue Collaboration Agreement. As such, all subsequent milestone payments are recognized as revenue when the risk of significant reversal is resolved. Future potential milestone payments were excluded from the transaction price as they are fully constrained as the risk of significant reversal has not yet been resolved. Royalty payments would be recognized when the sale occurs. Tufts University In February 1997, the Company and Tufts University, or Tufts, entered into a license agreement under which the Company acquired an exclusive license to certain patent applications and other intellectual property of Tufts related to the drug resistance field to develop and commercialize products for the treatment or prevention of bacterial or microbial diseases or medical conditions in humans or animals or for agriculture. The Company subsequently entered into eleven amendments to that agreement, collectively the Tufts License Agreement, to include patent applications filed after the effective date of the original license agreement, to exclusively license additional technology from Tufts, to expand the field of the agreement to include disinfectant applications, and to change the royalty rate and percentage of sublicense income paid by the Company to Tufts under sublicense agreements with specified sublicensees. The Company is obligated under the Tufts License Agreement to provide Tufts with annual diligence reports and a business plan and to meet certain other diligence milestones. The Company has the right to grant sublicenses of the licensed rights to third parties, which will be subject to the prior approval of Tufts unless the proposed sublicensee meets a certain net worth or market capitalization threshold. The Company is primarily responsible for the preparation, filing, prosecution and maintenance of all patent applications and patents covering the intellectual property licensed under the Tufts License Agreement at its sole expense. The Company has the first right, but not the obligation, to enforce the licensed intellectual property against infringement by third parties. The Company issued Tufts 1,024 shares of the Company’s common stock on the date of execution of the original license agreement, and the Company may be required to make certain payments of up to $0.3 million to Tufts upon the achievement by products developed under the agreement of specified development and regulatory approval milestones. The Company has already made a payment of $50,000 to Tufts for achieving the first milestone following commencement of the Phase 3 clinical trial for omadacycline and a payment of $100,000 to Tufts for achieving the second milestone following its first marketing application (NDA) submitted in the United States. The Company is also obligated to pay Tufts a minimum royalty payment in the amount of $25,000 per year. In addition, the Company is obligated to pay Tufts royalties based on gross sales of products, as defined in the agreement, ranging in the low single digits depending on the applicable field of use for such product sale. If the Company enters into a sublicense under the agreement, based on the applicable field of use for such product, the Company will be obligated to pay Tufts (i) a percentage, ranging from 10% to 14% (ten percent to fourteen percent) for compounds other than omadacycline, and a percentage in the single digits for the compound omadacycline, of that portion of any sublicense issue fees or maintenance fees received by the Company that are reasonably attributable to the sublicense of the rights granted to the Company under the Tufts License Agreement and (ii) the lesser of (a) a percentage, ranging from the low tens to the high twenties based on the applicable field of use for such product, of the royalty payments made to the Company by the sublicensee or (b) the amount of royalty payments that would have been paid by the Company to Tufts if it had sold the product. The Company paid a sublicense issue fee to Tufts during the year ended December 31, 2017 upon earning the $7.5 million upfront payment under the Zai Collaboration Agreement. Unless terminated earlier, the Tufts License Agreement will expire at the same time as the last-to-expire patent in the patent rights licensed to the Company under the agreement and after any such expiration the Company will continue to have an exclusive, fully-paid-up license to such intellectual property licensed from Tufts. Tufts has the right to terminate the agreement upon 30 days’ notice should the Company fail to make a material payment under the Tufts License Agreement or commit a material breach of the agreement and not cure such failure or breach within such 30-day period, or if, after the Company has started to commercialize a product under the Tufts License Agreement, the Company ceases to carry on its business for a period of 90 consecutive days. The Company has the right to terminate the Tufts License Agreement at any time upon 180 days’ notice. Tufts has the right to convert the Company’s exclusive license to a non-exclusive license if the Company does not commercialize a product licensed under the agreement within a specified time period. Past Collaborations Novartis In September 2009, the Company and Novartis International Pharmaceutical Ltd., or Novartis, entered into a Collaborative Development, Manufacture and Commercialization License Agreement, or the Novartis Agreement, which provided Novartis with a global, exclusive patent and technology license for the development, manufacturing and marketing of omadacycline. The Novartis Agreement was terminated by Novartis without cause in June 2011 and the termination was effective 60 days later. We and Novartis subsequently entered in a letter agreement in January 2012, or the Novartis Letter Agreement, as amended, pursuant to which we reconciled shared development costs and expenses and granted Novartis a right of first negotiation with respect to commercialization rights of omadacycline following approval of omadacycline from the FDA, EMA, or any regulatory agency, but only to the extent the Company had not previously granted such commercialization rights related to omadacycline to another third party as of any such approval. The Company also agreed to pay Novartis a 0.25% royalty, to be paid from net sales received by the Company in any country following the launch of omadacycline in that country and continuing until the later of expiration of the last active valid patent claim covering such product in the country of sale and 10 years from the date of first commercial sale in such country. The amended Novartis Letter Agreement resulted in a long-term liability in the amount of $3.6 million for the year ended March 31, 2018 and December 31, 2017 included within “Other Long-Term Liabilities” on the Company’s consolidated balance sheet. There are no other payment obligations to Novartis under the Novartis Agreement or the amended Novartis Letter Agreement.

Capital Stock

Capital Stock	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Capital Stock	9. Capital Stock In October 2015 and February 2017, the Company entered into Controlled Equity Offering SM 96,308 Warrants to Purchase Common Stock Warrants to purchase preferred stock with intrinsic value issued to HBM Healthcare Investments (Cayman) Ltd., Omega Fund III, L.P., and K/S Danish BioVenture, all beneficial owners of more than 5% of the Company’s common stock, were exchanged for 9,614 warrants to purchase common stock in connection with the Merger. These 9,614 warrants to purchase common stock have an exercise price of $0.15 per share and will, if not exercised, expire in 2021. As described in Note 13, Long-term Debt As described in Note 13, Long-term Debt Long-term Debt The Hercules Warrants, Loan Amendment Warrants and Additional Warrant, collectively referred to as the Warrants, may be exercised on a cashless basis. The Warrants are exercisable for a term beginning on the date of issuance and ending on the earlier to occur of five years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the various agreements for the Warrants.

Other Accrued Expenses

Other Accrued Expenses	3 Months Ended
	Mar. 31, 2018
Payables And Accruals [Abstract]
Other Accrued Expenses	10. Other Accrued Expenses Other accrued expenses consist of the following (in thousands): March 31, 2018 December 31, 2017 Accrued legal costs 485 257 Accrued compensation 1,706 3,403 Intermezzo payable — 124 Accrued professional fees 950 953 Accrued contract research 2,200 2,360 Accrued commercial 1,396 911 Accrued other 201 262 Total $ 6,938 $ 8,270

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	11. Fair Value Measurements Financial instruments, including cash, cash equivalents, restricted cash, money market funds, U.S. treasury and government agency securities, accounts receivable, accounts payable, accrued expenses, contingent obligations and the Intermezzo reserve are carried on the condensed consolidated financial statements at amounts that approximate fair value. The fair value of the Company’s long-term debt is determined using current applicable rates for similar instruments as of the balance sheet date. The carrying value of the long-term debt approximates its fair value as the interest rate is near current market rates. The fair value of the Company’s long-term debt was determined using Level 3 inputs. Fair values are based on assumptions concerning the amount and timing of estimated future cash flows and assumed discount rates, reflecting varying degrees of perceived risk. The following table presents information about the Company’s financial assets and liabilities that have been measured at fair value as of March 31, 2018 and December 31, 2017, and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities or other inputs that are observable market data. Fair values determined by Level 3 inputs utilize unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability (in thousands): Description Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total March 31, 2018 Assets: U.S. treasury securities $ 134,251 $ — $ — $ 134,251 Government agencies — $ 800 — 800 Total Assets $ 134,251 $ 800 $ — $ 135,051 Liabilities: Contingent obligations $ — $ — $ 56 $ 56 Total Liabilities $ — $ — $ 56 $ 56 December 31, 2017 Assets: U.S. treasury securities $ 114,508 $ — $ — $ 114,508 Government agencies — 1,799 — 1,799 Total Assets $ 114,508 $ 1,799 $ — $ 116,307 Liabilities: Contingent obligations $ — $ — $ 71 $ 71 Total Liabilities $ — $ — $ 71 $ 71 Marketable Securities U.S. treasury securities fair values can be obtained through quoted market prices in active exchange markets and are therefore classified as Level 1. The pricing on government agency securities was primarily sourced from independent third-party pricing services, overseen by management, and is based on valuation models that consider standard input factor such as deal quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment spreads, credit information and the bond’s terms and conditions, among other things, and are therefore classified as Level 2. Contingent Consideration On October 28, 2016, in satisfaction of the Company’s payment obligation of the proceeds of sale or disposition of the Intermezzo product rights to the former Transcept stockholders under the Merger Agreement, the Company executed the Royalty Sharing Agreement with the Special Committee. Under the Royalty Sharing Agreement, the Company agreed to pay to the former Transcept stockholders fifty percent of all royalty income received by the Company pursuant to the Purdue Collaboration Agreement, net of all costs, fees and expenses incurred by the Company in connection with the Purdue Collaboration Agreement, related agreements, the Intermezzo product and the administration of the royalty income to the former Transcept stockholders. The significant unobservable inputs used in the fair value measurement of the contingent obligation to former Transcept stockholders with respect to the Intermezzo product rights as of March 31, 2018 and December 31, 2017 were estimated future Intermezzo product revenues and associated royalties due to the Company as well as the appropriate discount rate given consideration to the market and forecast risk involved. The results of this valuation yielded a decrease in the contingent obligation to former Transcept stockholders of $15,000 during the three months ended March 31, 2018. Significant increases or decreases in any of those inputs would result in a substantially lower or higher fair value measurement. The following table provides a roll forward of the fair value of contingent obligations categorized as Level 3 instruments, for the three months ended March 31, 2018 (in thousands): Contingent liability— former Transcept stockholders Balances at December 31, 2017 $ 71 Change in fair value (15 ) Balances at March 31, 2018 $ 56

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	12. Stock-Based Compensation The following table presents stock-based compensation expense included in the Company’s condensed consolidated statements of operations (in thousands): Three Months Ended March 31, 2018 2017 Research and development expense $ 1,460 $ 1,339 General and administrative expense 2,907 2,705 Total stock-based compensation expense $ 4,367 $ 4,044 Stock-based compensation expense is estimated as of the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period. The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. The weighted-average assumptions used to determine the fair value of the stock option grants is as follows: Three Months Ended March 31, 2018 2017 Volatility 68.2 % 76.4 % Weighted average risk-free interest rate 2.6 % 2.0 % Expected dividend yield 0.0 % 0.0 % Expected life of options (in years) 5.9 5.8 Stock Option Plan Activity The Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2015 Equity Incentive Plan, or the 2015 Plan, which was approved by Company stockholders at the annual meeting of shareholders held on June 9, 2015, reserving 1,200,000 shares of common stock for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, RSU awards, performance stock awards, performance cash awards and other stock awards to directors, officers, employees and consultants. The 2015 Plan is intended to be the successor to and continuation of the Paratek Pharmaceuticals, Inc, 2006 Incentive Award Plan and the Paratek Pharmaceuticals, Inc. 2014 Equity Incentive Plan, or collectively, the Prior Plans. When the 2015 Plan became effective, no additional stock awards were granted under the Prior Plans, although all outstanding stock awards granted under the Prior Plans will continue to be subject to the terms and conditions as set forth in the agreements evidencing such stock awards and the terms of the Prior Plans. On January 1, 2018, 1 ,397,05 st st st st Total shares available for future issuance under the 2015 Plan are 243,185 shares as of March 31, 2018. During the three months ended March 31, 2018, the Company’s Board of Directors granted 50,800 stock options and 1,139,370 RSUs to directors, executives and employees of the Company under the 2015 Plan. The stock option awards are subject to time-based vesting over a period of one to four years. The RSU awards made to directors of the Company are subject to time-based vesting, with 100% of the shares of common stock subject to the RSUs vesting one year from the grant date. The RSU awards made to executives and employees are subject to time-based vesting over a period of three years from the grant date. The grants also included performance-based RSU, or PRSU, awards to certain executives and employees of the Company. The PRSU awards issued during the March 31, 2018 have vested or will vest as follows: (a) 10/55 shall be earned and time vest on achievement of European Medicines Agency, or EMA, filing preliminary validation, (b) 20/55 shall be earned and time vest on achievement of EMA approval, and (c) 25/55 shall be earned on achievement of the launch of Omadacycline in the U.S. and time vest on the date that is 15 months following such launch date. The Company recognizes the compensation cost of awards subject to performance-based vesting conditions over the requisite service period, to the extent achievement of the performance condition is deemed probable relative to targeted performance using the accelerated attribution method. If achievement of the performance condition is not probable, but the award will vest based on the service condition, the Company recognizes the expense over the requisite service period. A change in the requisite service period that does not change the estimate of the total compensation cost (i.e., it does not affect the grant-date fair value or quantity of awards to be recognized) is recognized prospectively over the remaining requisite service period. Since the Company believes it is more likely than not that milestone (a) above will be achieved, the Company recognized compensation cost, for a total of $0.2 million for the performance condition during the three months ended March 31, 2018 using the accelerated attribution method. The Company recognized an additional $0.5 million in PRSU expense related to previously granted awards that were more likely than not to be achieved during the three months ended March 31, 2018, related to NDA acceptance, which occurred in April 2018. The Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2015 Inducement Plan, or the 2015 Inducement Plan, in accordance with Nasdaq Rule 5635(c)(4), reserving 360,000 shares of common stock solely for the grant of inducement stock options 106,500 In June 2017, the Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2017 Inducement Plan, or the 2017 Inducement Plan, in accordance with Nasdaq Rule 5635(c)(4), reserving 550,000 shares of common stock solely for the grant of inducement stock options and RSU awards to employees entering into employment or returning to employment after a bona fide period of non-employment with the Company. During the March 31, 2018, Stock options A summary of stock option activity for the three months ended March 31, 2018 is as follows: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 3,608,907 $ 17.01 7.78 $ 13,311 Granted 166,150 14.52 Exercised (28,699 ) 6.15 Cancelled or forfeited (15,424 ) 15.78 Expired (40,000 ) 29.80 Outstanding at March 31, 2018 3,690,934 $ 16.84 7.74 $ 5,540 Exercisable at March 31, 2018 2,319,142 $ 16.35 7.27 $ 5,107 Restricted Stock Units A summary of RSU activity for the three months ended March 31, 2018 is as follows: Number of Shares Weighted Average Grant Date Fair Value Unvested Balance at December 31, 2017 1,167,703 $ 18.43 Granted 1,174,270 14.31 Released (171,999 ) 19.30 Unvested Balance at March 31, 2018 2,169,974 $ 16.13 Total unrecognized compensation expense for all stock-based awards was $26.6 million as of March 31, 2018. This amount will be recognized over a weighted average period of 2.18 years.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt	13. Long-term Debt Loan Agreement On September 30, 2015, the Company entered into the Hercules Loan Agreement with Hercules and certain other lenders, and Hercules Technology Growth Capital, Inc. (as agent). Under the Hercules Loan Agreement, Hercules provided the Company with access to term loans with an aggregate principal amount of up to $40.0 million, or collectively, the Term Loan. The Company initially drew a principal amount of $20.0 million, which was funded on September 30, 2015. The remaining $20.0 million under the Hercules Loan Agreement was available to be drawn at the Company’s option in minimum increments of $10.0 million through December 31, 2016, or the Draw Period. The Term Loan was repayable in monthly installments commencing on April 1, 2018 through maturity on September 1, 2020. The interest rate was equal to the greater of (i) 8.5%, or (ii) the sum of 8.5%, plus the “prime rate” as reported in The Wall Street Journal minus 5.75% per annum. An end of term charge equal to 4.5% of the issued principal balance of the Term Loan was payable at maturity, including in the event of any prepayment, and was being accrued as interest expense over the term of the loan using the effective interest method. Borrowings under the Hercules Loan Agreement were collateralized by substantially all of the assets of the Company. Upon an Event of Default, an additional 5.0% interest would be applied and Hercules could, at its option, accelerate and demand payment of all or any part of the loan together with the prepayment and end of term charges. An Event of Default is defined in the Hercules Loan Agreement as (i) failure to make required payments; (ii) failure to adhere to financial, operating and reporting loan covenants; (iii) an event or development occurs that would be reasonably expected to have a material adverse effect; (iv) false representations in the Hercules Loan Agreement; (v) insolvency, as described in the Hercules Loan Agreement; (vi) levy or attachments on any of the Company's assets; and (vii) default of any other agreement or subordinated debt greater than $1.0 million. In the event of insolvency, this acceleration and declaration would be automatic. In addition, in connection with the Hercules Loan Agreement, the Company agreed to provide Hercules with a contingent security interest in the Company's bank accounts. The Company's control of its bank accounts is not adversely affected unless Hercules elects to obtain unilateral control of the Company's bank accounts by declaring that an Event of Default has occurred. The principal of the Term Loan which was not due within 12 months of March 31, 2018 has been classified as long-term debt as the Company determined that a material adverse effect resulting in Hercules exercising its rights under the subjective acceleration clause is remote. Subject to certain terms, pursuant to the Hercules Loan Agreement, Hercules was also granted the right to participate in an amount of up to $2.0 million in subsequent sales and issuances of the Company's equity securities to one or more investors for cash for financing purposes in an offering that is broadly marketed to multiple investors and at the same terms as the other investors. On September 30, 2015, Hercules Technology Growth Capital, Inc. entered into a Stock Purchase Agreement with the Company to purchase 44,782 shares of common stock resulting in proceeds to the Company of approximately $1.0 million. The excess of proceeds received by the Company over the fair value of the common stock issued was allocated as a reduction of the fees paid to Hercules in conjunction with obtaining the initial $20.0 million draw of the Term Loan. Debt issuance costs of $511,000 were ratably allocated to the initial $20.0 million draw and the remaining unfunded $20.0 million. Debt issuance costs related to the initial $20.0 million draw were presented on the consolidated balance sheet as a direct deduction from the related debt liability. Issuance costs related to the unfunded amount were capitalized as prepaid asset and were to be amortized ratably through the end of the Draw Period. In connection with the Hercules Loan Agreement, the Company issued to each of Hercules Technology II, L.P. and Hercules Technology III, L.P., a warrant to purchase 16,346 shares of the Company’s common stock (32,692 shares of common stock in total) at an exercise price of $24.47 per share. The Hercules Warrants’ total relative fair value of $288,000 at September 30, 2015 was determined using a Black-Scholes option-pricing model. The relative fair value of the Hercules Warrants was included as a discount to the Term Loan and also as a component of additional paid-in capital. See Note 9, Capital Stock In addition to the Hercules Warrants, the Company paid fees to Hercules in conjunction with obtaining the Term Loan. The Hercules Warrants fair value and fees paid to Hercules, an aggregate of $572,000, were ratably allocated to the initial $20.0 million draw and the remaining unfunded $20.0 million. The $208,000 of costs allocated to the initial $20.0 million draw were recorded as a debt discount and are being amortized as additional interest expense over the term of the loan using the effective interest method. The $364,000 of costs allocated to the unfunded $20.0 million was recorded as prepaid expenses and were being amortized ratably through the end of the Draw Period. In the event the Company exercised its option to borrow additional funds, the remaining unamortized prepaid asset balance related would be reclassified and recorded as debt discount based upon a ratable allocation of the amount drawn compared to the remaining unfunded amount available to the Company and would amortize over the remaining life of the term loan using the effective interest method. On December 12, 2016, the Company and Hercules entered into a second amendment to the Hercules Loan Agreement, or the Second Amendment, which extended the date on which the Company must begin making amortization payments under the Hercules Loan Agreement from April 1, 2018 to January 1, 2019, or the Amortization Date. Upon commencement of the Amortization Date, the Company will make amortization payments based upon an amortization schedule equal to thirty consecutive months, with the balance of outstanding loans due on the original maturity date of the Hercules Loan Agreement. The Second Amendment also increased the amount that the Company may borrow by $10.0 million, from up to $40.0 million to up to $50.0 million in multiple tranches. In connection with the Second Amendment the Company paid Hercules a $0.4 million amendment fee. In connection with the Second Amendment, the Company issued to each one of Hercules Technology II, L.P. and Hercules Technology III, L.P. a warrant to purchase 18,574 shares of its common stock (37,148 shares of common stock in total) at an exercise price of $13.46 per shares. Under the Second Amendment the end of term charge was equal to 4.5% of the issued principal balance of the Hercules Loan Agreement, and was payable at maturity, including in the event of any prepayment, and is being accrued as interest expense over the term of the loan using the effective interest method. Borrowings under the Hercules Loan Agreement are still collateralized by substantially all of the assets of the Company. On June 27, 2017, the Company and Hercules entered into a third amendment to the Hercules Loan Agreement, or the Third Amendment. The Third Amendment increased the amount that the Company may borrow by $10.0 million, from up to $50.0 million to up to $60.0 million, in multiple tranches. The additional $10.0 million tranche, or the Fourth Tranche, was available at the Company’s option through December 15, 2017. The Fourth Tranche shall bear interest and have the same maturity as all other loans outstanding under the Hercules Loan Agreement, as amended. The Company borrowed the first tranche of $20.0 million upon the closing of the Hercules Loan Agreement on September 30, 2015, and the second tranche of $20.0 million on December 12, 2016, or collectively, the Initial Tranches. Concurrently with the closing of the Third Amendment, the Company borrowed a third tranche of $10.0 million, or the Third Tranche. The Third Amendment extended the date on which the Company is required to begin making monthly principal installments under the Hercules Loan Agreement from January 1, 2019 to January 1, 2020, subject to the Company’s receipt of marketing approval for the Company’s lead product candidate, omadacycline, or the Interest Only Period Extension Event. Beginning on January 1, 2019, or, if the Company achieves the Interest Only Period Extension Event, beginning on January 1, 2020, the Company will make payments in equal monthly installments of principal and interest, with the balance of outstanding loans due on the original maturity date of the Hercules Loan Agreement. In connection with the Third Amendment, the Company paid Hercules a $0.1 million amendment fee. The Third Amendment reduced the end of term charge due with respect to the Third Tranche from to 4.5% to 2.25% if the obligations under the Hercules Loan Agreement were repaid in full on or prior to September 30, 2017, following Hercules’ election not to consent to a proposed third-party, non-equity financing arrangement (excluding any stock issuance). The end of term charge with respect to the Fourth Tranche is 2.25%. If the Company prepays the loan prior to maturity, it will pay a prepayment charge, based on a percentage of the then outstanding principal balance, equal to (i) 1% with respect to the Third Tranche and the Fourth Tranche or (ii) 2% with respect to the Initial Tranches if the prepayment occurs prior to April 1, 2019, or equal to 0% if the prepayment occurs on or after April 1, 2019. In connection with the borrowing of the Third Tranche, on June 27, 2017, the Company issued an additional warrant to Hercules Capital, Inc. that is exercisable for an aggregate of 5,374 shares of common stock at an exercise price of $23.26 per share. The Additional Warrant may be exercised on a cashless basis. The Additional Warrant is exercisable for a term beginning on the date of issuance and ending on the earlier to occur of five years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the Additional Warrant. In connection with the offering of the Notes, discussed below, on April 17, 2018, the Company entered into Amendment No. 4, or the Fourth Amendment, to the Hercules Loan Agreement. The Fourth Amendment increases the amount of permitted indebtedness to an amount not to exceed $2.0 million and permits the Company to issue convertible notes in an aggregate principal amount of not more than $172.5 million provided that such convertible notes meet certain stipulations. As of March 31, 2018, the Company has recorded a current portion of long-term debt obligation of $7.6 million, net of debt discount of $0.4 million, and a long-term debt obligation of $51.7 million, net of debt discount of $0.3 million. Future principal payments, which exclude the end of term charge in connection with the Hercules Loan Agreement, as amended, as of March 31, 2018, are as follows (in thousands): Fiscal Year 2018 $ — 2019 33,140 2020 26,860 2021 — 2022 and Thereafter — Total $ 60,000 Convertible Senior Subordinated Notes On April 18, 2018, the Company entered into a Purchase Agreement, or the Purchase Agreement, with the several initial purchasers, or the Initial Purchasers, for whom Merrill Lynch, Pierce, Fenner & Smith Incorporated The Purchase Agreement includes customary representations, warranties and covenants. Under the terms of the Purchase Agreement, the Company has agreed to indemnify the Initial Purchasers against certain liabilities. In addition, J. Wood Capital Advisors LLC, the Company’s financial advisor, purchased $5.0 million aggregate principal amount of Notes in a separate, concurrent private placement on the same terms as other investors. The Notes were issued by the Company on April 23, 2018, pursuant to an Indenture, dated as of such date, or the Indenture, between the Company and U.S. Bank National Association, as trustee, or the Trustee. The Notes bear cash interest at the annual rate of 4.75%, payable on November 1 and May 1 of each year, beginning on November 1, 2018, and mature on May 1, 2024 unless earlier repurchased, redeemed or converted. The Company will settle conversions of the Notes through delivery of shares of common stock of the Company, in accordance with the terms of the Indenture. The initial conversion rate for the Notes is 62.8931 shares of common stock (subject to adjustment as provided for in the Indenture) per $1,000 principal amount of the Notes, which is equal to an initial conversion price of approximately $15.90 per share, representing a conversion premium of approximately 20% above the closing price of the common stock of $13.25 per share on April 18, 2018. Holders of the Notes may convert all or any portion of their Notes, in multiples of $1,000 principal amount, at their option at any time prior to the close of business on the second scheduled trading day immediately preceding the stated maturity date. The Company may not redeem the Notes prior to May 6, 2021. The Company may redeem for cash all or part of the Notes, at its option, on or after May 6, 2021 if the last reported sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. If the Company experiences a fundamental change, as described in the Indenture, prior to the maturity date of the Notes, holders of the Notes will, subject to specified conditions, have the right, at their option, to require the Company to repurchase for cash all or a portion of their Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest, if any, to, but not including, the fundamental change repurchase date. In addition, following certain corporate events that occur prior to the maturity date of the Notes and following a notice of redemption of the notes, the Company will increase the conversion rate for a holder who elects to convert its Notes in connection with such corporate event or redemption. The Indenture provides for customary events of default. In the case of an event of default with respect to the Notes arising from specified events of bankruptcy or insolvency, all outstanding Notes will become due and payable immediately without further action or notice. If any other event of default with respect to the Notes under the Indenture occurs or is continuing, the Trustee or holders of at least 25% in aggregate principal amount of the then outstanding Notes may declare the principal amount of the Notes to be immediately due and payable. In certain circumstances if, at any time during the six-month period beginning on, and including, the date that is six months after the last date of original issuance of the Notes, the Company fails to timely file certain documents or reports required under the Securities Exchange Act of 1934, as amended, or the Notes are not otherwise freely tradable by holders of the Notes other than the Company’s affiliates or holders that were the Company’s affiliates at any time during the three months immediately preceding, additional interest will accrue on the Notes during the first 90-day period in which its failure to file has occurred and is continuing or such Notes are not otherwise freely tradable by holders other than the Company’s affiliates (or holders that were the Company’s affiliates at any time during the three months immediately preceding). In addition, if, and for so long as, the restrictive legend on the Notes has not been removed, the Notes are assigned a restricted CUSIP number or the Notes are not otherwise freely tradable by holders other than the Company’s affiliates or holders that were our affiliates at any time during the three months immediately preceding (without restrictions pursuant to U.S. securities laws or the terms of the Indenture or the Notes) as of the 380th day after the last date of original issuance of the Notes, the Company will pay additional interest on the Notes outstanding during the period in which the Notes remain so restricted. The Company received net proceeds of $158.8 million after deducting commissions, fees and other offering expenses of $6.2 million.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	14 . The Company recorded no provision for income taxes for the three months ended March 31, 2018 and 2017. Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax bases of assets and liabilities using statutory rates. Management of the Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are comprised principally of net operating loss carryforwards and research and development credits. Under the applicable accounting standards, management has considered the Company’s history of losses and concluded that it is more likely than not that the Company will not recognize the benefits of federal and state deferred tax assets. Accordingly, a full valuation allowance has been established against the Company’s otherwise recognizable net deferred tax assets. On December 22, 2017, the new tax reform law, which is commonly referred to as the Tax Cuts and Jobs Act, or the Act, was signed into law by President Trump. The Act includes a number of provisions, including the lowering of the U.S. corporate tax rate from 35 percent to 21 percent, effective January 1, 2018 and the establishment of a territorial-style system for taxing foreign-source income of domestic multinational corporations. The Company is in the process of quantifying the tax impacts of the Act. Due to the Company's full valuation allowance, no provisional tax expense or benefit associated with the re-measurement was recognized in the Company's consolidated statement of operations and comprehensive loss for the period ended March 31, 2018. The Company has recognized the provisional tax impacts related to the revaluation of the deferred tax assets and liabilities and included these amounts in its consolidated financial statements for the year ended December 31, 2017. On December 22, 2017, the SEC staff issued SAB 118 to address the application of GAAP in situations when a registrant does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Act. The Company has recognized the provisional tax impacts related to the revaluation of the deferred tax assets and liabilities and included these amounts in its consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from these provisional amounts due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of The Act, which could result in changes to the provisional tax impacts during 2018.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Leases The Company’s contractual obligations and commitments were reported in its Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 6, 2018. The Company leases its Boston, Massachusetts and King of Prussia, Pennsylvania office spaces under non-cancelable operating leases expiring in 2021 and 2024, respectively. As of March 31, 2018, future minimum lease payments under operating leases are as follows: Fiscal Year Remainder of 2018 $ 869 2019 1,156 2020 1,178 2021 964 2022 508 2023 and Thereafter 914 Total $ 5,589 Intermezzo Patent Litigation In July 2012, the Company received notifications from three companies, Actavis Elizabeth LLC, or Actavis Elizabeth, Watson Laboratories, Inc.—Florida, or Watson, and Novel Laboratories, Inc., or Novel, in September 2012, from each of Par Pharmaceutical, Inc. and Par Formulations Private Ltd., together, the Par Entities, in February 2013 from Dr. Reddy’s Laboratories, Inc. and Dr. Reddy’s Laboratories, Ltd., together, Dr. Reddy’s, and in July 2013 from TWi Pharmaceuticals, Inc., or Twi, stating that each has filed with the FDA an ANDA, that references Intermezzo. Refer to Item 3, “ Legal Proceedings” The United States District Court for the District of New Jersey, or the New Jersey District Court, held a consolidated trial between December 1, 2014 and December 15, 2014 involving Paratek, Purdue Pharma, and their patent infringement claims against Actavis Elizabeth, Novel, and Dr. Reddy’s. The New Jersey District Court then received post-trial briefing and held a February 13, 2015 post-trial hearing. On March 27, 2015, the New Jersey District Court issued an order and accompanying opinion finding that: (a) the asserted claims of U.S. Patent Nos. 7,682,628, 8,242,131, and 8,252,809, are invalid as obvious; (b) Actavis Elizabeth, Novel, and Dr. Reddy’s infringe the ‘131 patent; (c) Novel infringes the ‘628 patent; and (d) Novel and Dr. Reddy’s infringe the ‘809 patent. On April 9, 2015, the New Jersey District Court entered final judgment consistent with the March 27, 2015 opinion and order referenced above. The Company and Purdue Pharma jointly appealed the New Jersey District Court’s final judgment as to the '131 patent to the United States Court of Appeals for the Federal Circuit on May 6, 2015. On January 8, 2016, the United States Court of Appeals for the Federal Circuit affirmed the decision of the New Jersey District Court, and no opinion accompanied the judgment. On September 14, 2016, the defendants filed a warrant of satisfaction of judgment in the New Jersey District Court for the costs having been fully paid to the defendants. Patent Term Adjustment Suit In January 2013, the Company filed suit in the Eastern District of Virginia against the United States Patent and Trademark Office, or the USPTO, seeking recalculation of the patent term adjustment of the ’131 Patent. Purdue Pharma has agreed to bear the costs and expenses associated with this litigation. In June 2013, the judge granted a joint motion to stay the proceedings pending a remand to the USPTO, in which the USPTO is expected to reconsider its patent term adjustment award in light of decisions in a number of appeals to the Federal Circuit, including Novartis AG v. Lee 740 F.3d 593 (Fed. Cir. 2014), or the Novartis decision. Since having issued final rules implementing the Novartis decision, the USPTO has been working through the civil action cases and issuing remand decisions. The Company’s case was on remand until the USPTO made its decision on the recalculation of the patent term adjustment. On September 28, 2016, the USPTO issued a decision that the patent term adjustment is 1,038 days, from which the ‘131 Patent expiration would be March 26, 2029. Other Legal Proceedings In the ordinary course of business, the Company is from time to time involved in lawsuits, claims, investigations, proceedings, and threats of litigation relating to intellectual property, commercial arrangements, employment and other matters. While the outcome of these proceedings and claims cannot be predicted with certainty, as of March 31, 2018, the Company was not party to any other legal or arbitration proceedings that may have, or have had in the recent past, significant effects on the Company’s financial position. No governmental proceedings are pending or, to the Company’s knowledge, contemplated against the Company. The Company is not a party to any material proceedings in which any director, member of executive management or affiliate of the Company is either a party adverse to the Company or the Company’s subsidiaries or has a material interest adverse to the Company or the Company’s subsidiaries.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Recent Accounting Pronouncements	16. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) The amendment requires a lessee to recognize assets and liabilities for leases with a maximum possible term of more than 12 months. A lessee would recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the leased asset (the underlying asset) for the lease term. This ASU is effective for fiscal years and interim periods beginning after December 15, 2018. The Company is currently evaluating the impact the adoption of the ASU will have on its consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment In May 2017, the FASB issued ASU 2017-09, Compensation – Stock Compensation The new standard will be effective beginning January 1, 2019.

Summary of Significant Accoun22

Summary of Significant Accounting Policies and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	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 consolidated financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 6, 2018. Statement of Cash Flows On January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230) Restricted Cash , or ASU 2016-18. The Company’s restricted cash is now included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the Company’s condensed consolidated statement of cash flows. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated statement of cash flows that sum to the total of the same such amounts shown in the condensed consolidated statement of cash flows. March 31, 2018 December 31, 2017 March 31, 2017 Cash and cash equivalents $ 49,273 $ 35,416 $ 62,044 Short-term restricted cash 229 162 127 Long-term restricted cash 250 250 250 Total cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows $ 49,752 $ 35,828 $ 62,421 Revenue Recognition Effective January 1, 2018, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers The Company enters into collaboration agreements for research, development, manufacturing and commercial services that are within the scope of ASC 606, under which it licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period. The contracts into which the Company enters generally do not include significant financing components. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the transaction price under step (iii) above and (b) the timing of revenue recognition, including the appropriate measure of progress in step (v) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties, should be included in the transaction price, as described further below. The transaction price is allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. If a milestone or other variable consideration relates specifically to the Company’s efforts to satisfy a single performance obligation or to a specific outcome from satisfying the performance obligation, the Company generally allocates the milestone amount entirely to that performance obligation once it is probable that a significant revenue reversal would not occur. Amounts received prior to revenue recognition are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Licenses of intellectual property In assessing whether a license is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a license for its intended purpose without the receipt of the remaining promise(s), whether the value of the license is dependent on the unsatisfied promise(s), whether there are other vendors that could provide the remaining promise(s), and whether it is separately identifiable from the remaining promise(s). For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Customer options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent or include a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the probability that the customer will exercise. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone payments At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant reversal of cumulative revenue would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Contract costs The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. As a practical expedient, the Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. To date, the Company has not incurred any incremental costs of obtaining a contract with a customer. Impact of adoption As a result of adopting ASC 606 on January 1, 2018, there are no significant changes to the revenue recognition pattern for any of the Company’s license and collaboration agreements. For further discussion of the adoption of this standard, and for a discussion of accounting for collaboration revenue, see Note 8, License and Collaboration Agreements There have been no other material changes in the Company’s significant accounting policies during the three months ended March 31, 2018.
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles of the United States of America, or U.S. GAAP, as found in the ASC and ASU of the Financial Accounting Standards Board, or FASB, and pursuant to the rules and regulations of the SEC. The accompanying condensed consolidated financial statements are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements as of and for the year ended December 31, 2017, except as described above related to the adoption of ASU 2016-15 and ASC 606 and, in the opinion of management, reflect all normal recurring adjustments necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the interim period ended March 31, 2018. Beginning in the three months ended March 31, 2018, the Company presented “accrued contract manufacturing costs” as a separate line item on its condensed consolidated balance sheet. As such, the Company reclassified the December 31, 2017 accrued manufacturing balance of $5.0 million, from “other accrued expenses” into “accrued contract manufacturing costs”. The Company also reclassified the balance of “accrued contract research” of $2.4 million as of December 31, 2017, previously presented as a separate line within the Company’s consolidated balance sheet, into “other accrued expenses” on the condensed consolidated balance sheet as of March 31, 2018. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2018. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2017, and notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 6, 2018.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the results of operations of Paratek Pharmaceuticals, Inc. and its wholly-owned subsidiaries, Paratek Pharma, LLC, Paratek Securities Corporation, Transcept Pharma, Inc., Paratek UK, Ltd, Paratek Bermuda Ltd., and Paratek Ireland Limited. All significant intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the accompanying unaudited condensed consolidated financial statements, in conformity with U.S. GAAP, requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, and expenses and the disclosure of contingent liabilities in the Company’s financial statements. On an ongoing basis, the Company evaluates its estimates and judgments, including those related to,
Segment and Geographic Information	Segment and Geographic Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment.

Summary of Significant Accoun23

Summary of Significant Accounting Policies and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents, and Restricted Cash Reported Within Condensed Consolidated Statement of Cash Flows	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated statement of cash flows that sum to the total of the same such amounts shown in the condensed consolidated statement of cash flows. March 31, 2018 December 31, 2017 March 31, 2017 Cash and cash equivalents $ 49,273 $ 35,416 $ 62,044 Short-term restricted cash 229 162 127 Long-term restricted cash 250 250 250 Total cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows $ 49,752 $ 35,828 $ 62,421

Cash and Cash Equivalents and24

Cash and Cash Equivalents and Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Cash And Cash Equivalents [Abstract]
Summary of Available for Sale Securities	The following is a summary of available-for-sale securities as of March 31, 2018 and December 31, 2017 (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value March 31, 2018 U.S. treasury securities $ 134,431 $ — $ (180 ) $ 134,251 Government agencies 800 — — 800 Total $ 135,231 $ — $ (180 ) $ 135,051 December 31, 2017 U.S. treasury securities $ 114,666 $ — $ (158 ) $ 114,508 Government agencies 1,799 — — 1,799 Total $ 116,465 $ — $ (158 ) $ 116,307

Fixed Assets (Tables)

Fixed Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Property Plant And Equipment [Abstract]
Schedule of Fixed Assets, Net	Fixed assets, net, consists of the following (in thousands): March 31, 2018 December 31, 2017 Office equipment $ 866 $ 866 Computer equipment 412 412 Computer software 787 787 Leasehold improvements 860 860 Construction-in-process 23 — Gross fixed assets 2,948 2,925 Less: Accumulated depreciation and amortization (1,365 ) (1,214 ) Net fixed assets $ 1,583 $ 1,711

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets consist of the following (in thousands): March 31, 2018 December 31, 2017 Intermezzo product rights $ 142 $ 142 TO-2070 asset 170 170 Gross intangible assets 312 312 Less: Accumulated amortization (173 ) (170 ) Net intangible assets $ 139 $ 142

Net Loss Per Share Available 27

Net Loss Per Share Available to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Antidilutive Shares Excluded from Computation of Diluted Net Income (Loss) Per Share	The following outstanding shares subject to stock options, RSUs and warrants to purchase common stock were antidilutive due to a net loss in the periods presented and, therefore, were excluded from the dilutive securities computation as of the three months ended March 31, 2018 and 2017 as indicated below: March 31, 2018 2017 Excluded potentially dilutive securities (1) Shares subject to outstanding options to purchase common stock 3,690,934 3,452,076 Unvested restricted stock units 2,169,974 955,503 Shares subject to warrants to purchase common stock 84,828 79,454 Shares issuable under employee 2009 stock purchase plan 36,539 36,539 Totals 5,982,275 4,523,572 (1) The number of shares is based on the maximum number of shares issuable on exercise or conversion of the related securities as of March 31, 2018. Such amounts have not been adjusted for the treasury stock method or weighted average outstanding calculations as required if the securities were dilutive.

Other Accrued Expenses (Tables)

Other Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2018
Payables And Accruals [Abstract]
Schedule of Other Accrued Expenses	Other accrued expenses consist of the following (in thousands): March 31, 2018 December 31, 2017 Accrued legal costs 485 257 Accrued compensation 1,706 3,403 Intermezzo payable — 124 Accrued professional fees 950 953 Accrued contract research 2,200 2,360 Accrued commercial 1,396 911 Accrued other 201 262 Total $ 6,938 $ 8,270

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value	Fair values determined by Level 2 inputs utilize observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities or other inputs that are observable market data. Fair values determined by Level 3 inputs utilize unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability (in thousands): Description Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total March 31, 2018 Assets: U.S. treasury securities $ 134,251 $ — $ — $ 134,251 Government agencies — $ 800 — 800 Total Assets $ 134,251 $ 800 $ — $ 135,051 Liabilities: Contingent obligations $ — $ — $ 56 $ 56 Total Liabilities $ — $ — $ 56 $ 56 December 31, 2017 Assets: U.S. treasury securities $ 114,508 $ — $ — $ 114,508 Government agencies — 1,799 — 1,799 Total Assets $ 114,508 $ 1,799 $ — $ 116,307 Liabilities: Contingent obligations $ — $ — $ 71 $ 71 Total Liabilities $ — $ — $ 71 $ 71
Rollforward of Fair Value of Contingent Obligations	The following table provides a roll forward of the fair value of contingent obligations categorized as Level 3 instruments, for the three months ended March 31, 2018 (in thousands): Contingent liability— former Transcept stockholders Balances at December 31, 2017 $ 71 Change in fair value (15 ) Balances at March 31, 2018 $ 56

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-Based Compensation Expense Included in Company's Consolidated Statements of Operations	The following table presents stock-based compensation expense included in the Company’s condensed consolidated statements of operations (in thousands): Three Months Ended March 31, 2018 2017 Research and development expense $ 1,460 $ 1,339 General and administrative expense 2,907 2,705 Total stock-based compensation expense $ 4,367 $ 4,044
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The weighted-average assumptions used to determine the fair value of the stock option grants is as follows: Three Months Ended March 31, 2018 2017 Volatility 68.2 % 76.4 % Weighted average risk-free interest rate 2.6 % 2.0 % Expected dividend yield 0.0 % 0.0 % Expected life of options (in years) 5.9 5.8
Schedule of Share-based Compensation, Stock Options, Activity	A summary of stock option activity for the three months ended March 31, 2018 is as follows: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 3,608,907 $ 17.01 7.78 $ 13,311 Granted 166,150 14.52 Exercised (28,699 ) 6.15 Cancelled or forfeited (15,424 ) 15.78 Expired (40,000 ) 29.80 Outstanding at March 31, 2018 3,690,934 $ 16.84 7.74 $ 5,540 Exercisable at March 31, 2018 2,319,142 $ 16.35 7.27 $ 5,107
Schedule of Share-based Compensation, RSU, Activity	A summary of RSU activity for the three months ended March 31, 2018 is as follows: Number of Shares Weighted Average Grant Date Fair Value Unvested Balance at December 31, 2017 1,167,703 $ 18.43 Granted 1,174,270 14.31 Released (171,999 ) 19.30 Unvested Balance at March 31, 2018 2,169,974 $ 16.13

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	Future principal payments, which exclude the end of term charge in connection with the Hercules Loan Agreement, as amended, as of March 31, 2018, are as follows (in thousands): Fiscal Year 2018 $ — 2019 33,140 2020 26,860 2021 — 2022 and Thereafter — Total $ 60,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Operating Leases	As of March 31, 2018, future minimum lease payments under operating leases are as follows: Fiscal Year Remainder of 2018 $ 869 2019 1,156 2020 1,178 2021 964 2022 508 2023 and Thereafter 914 Total $ 5,589

Description of the Business - A

Description of the Business - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 18, 2018	Mar. 31, 2018	Dec. 31, 2017
Organization [Line Items]
Accumulated deficit		$ (497,860)	$ (470,112)
Existing cash, cash equivalents and available for sale marketable securities current		$ 184,300
Subsequent Event [Member]
Organization [Line Items]
Proceeds from issuance of convertible notes	$ 158,800

Summary of Significant Accoun34

Summary of Significant Accounting Policies and Basis of Presentation - Summary of Reconciliation of Cash, Cash Equivalents, and Restricted Cash Reported Within Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	$ 49,273	$ 35,416
Restricted cash	229	162
Long-term restricted cash	250	250
Total cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	49,752	35,828	$ 62,421	$ 54,029
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	49,273	35,416	62,044
Restricted cash	229	162	127
Long-term restricted cash	250	250	250
Total cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$ 49,752	$ 35,828	$ 62,421

Summary of Significant Accoun35

Summary of Significant Accounting Policies and Basis of Presentation - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)Segment	Dec. 31, 2017USD ($)
Accounting Policies [Line Items]
Accrued Contract Research Current	$ 2,200	$ 2,360
Number of operating segments | Segment	1
ASC 606 [Member]
Accounting Policies [Line Items]
Revenue recognition description	Amounts received prior to revenue recognition are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion.
Accounting Standards Update 201615 And ASC 606 [Member]
Accounting Policies [Line Items]
Accrued contract manufacturing costs		5,000
Accrued Contract Research Current		$ 2,400

Cash and Cash Equivalents and36

Cash and Cash Equivalents and Marketable Securities - Summary of Available for Sale Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 135,231	$ 116,465
Unrealized Losses	(180)	(158)
Fair Value	135,051	116,307
U.S. Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	134,431	114,666
Unrealized Losses	(180)	(158)
Fair Value	134,251	114,508
Government Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	800	1,799
Fair Value	$ 800	$ 1,799

Cash and Cash Equivalents and37

Cash and Cash Equivalents and Marketable Securities - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Available for sale securities have remaining maturities greater than one year	$ 0	$ 0

Restricted Cash - Additional In

Restricted Cash - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Restricted Cash And Cash Equivalents Items [Line Items]
Royalty income received but not yet paid	$ 0.2	$ 0.2
Letters of Credit [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Letters of credit amount collateralized	$ 0.3	$ 0.3

Fixed Assets - Schedule of Fixe

Fixed Assets - Schedule of Fixed Assets, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Gross fixed assets	$ 2,948	$ 2,925
Less: Accumulated depreciation and amortization	(1,365)	(1,214)
Net fixed assets	1,583	1,711
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross fixed assets	866	866
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross fixed assets	412	412
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Gross fixed assets	787	787
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross fixed assets	860	$ 860
Construction-in-process [Member]
Property, Plant and Equipment [Line Items]
Gross fixed assets	$ 23

Intangible Assets, Net - Schedu

Intangible Assets, Net - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross intangible assets	$ 312	$ 312
Less: Accumulated amortization	(173)	(170)
Net intangible assets	139	142
Intermezzo Product Rights [Member]
Finite Lived Intangible Assets [Line Items]
Gross intangible assets	142	142
TO-2070 Asset [Member]
Finite Lived Intangible Assets [Line Items]
Gross intangible assets	$ 170	$ 170

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Intermezzo Product Rights [Member]
Finite Lived Intangible Assets [Line Items]
Impairment of intangible assets	$ 0	$ 700,000

Net Loss Per Share Available 42

Net Loss Per Share Available to Common Stockholders - Antidilutive Shares Excluded from Computation of Diluted Net Income (Loss) Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded potentially dilutive securities	5,982,275	4,523,572
Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded potentially dilutive securities	3,690,934	3,452,076
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded potentially dilutive securities	2,169,974	955,503
Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded potentially dilutive securities	84,828	79,454
Employee 2009 Stock Purchase Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded potentially dilutive securities	36,539	36,539

License and Collaboration Agr43

License and Collaboration Agreements - Additional Information (Detail)

Oct. 28, 2016

Dec. 31, 2017USD ($)

Dec. 31, 2014USD ($)

Oct. 31, 2014

Jun. 30, 2014

Aug. 31, 2012USD ($)

Dec. 31, 2011USD ($)

Jul. 31, 2009

Feb. 28, 1997shares

Mar. 31, 2018USD ($)Obligation

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Jan. 31, 2012USD ($)

Jan. 31, 2010USD ($)

Dec. 31, 2016USD ($)

Aug. 31, 2009USD ($)

Transcept Pharmaceuticals, Inc. [Member] | Royalty Sharing Agreement [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of royalty income paid for payment obligation

50.00%

Allergan [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront license fee payment received and recognized as revenue

$ 5,000,000

$ 0

$ 0

Milestone payments on acceptance of an NDA submission

$ 12,000,000

Number of performance obligations | Obligation

2

Purdue Pharma [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Non-refundable license fees

$ 25,000,000

Range of company tier base royalties on net sales of Intermezzo

From the mid-teens up to the mid-20% level

Validity of collaboration agreement

15 years

Advance notice to terminate collaboration agreement

180 days

Rate of royalty receivable

100.00%

Cash proceeds from sale or disposition of intermezzo

90.00%

Purdue Pharma [Member] | Intellectual Property [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Non-refundable milestone payments made

$ 10,000,000

$ 10,000,000

Tufts [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Shares issued | shares

1,024

Milestone payments, maximum

$ 300,000

Milestone payments, paid

50,000

Second milestone payment

100,000

Royalty, payable

25,000

Maximum [Member] | Purdue Pharma [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Amount receivable on achievement of net sales criteria

$ 70,000,000

Maximum [Member] | Tufts [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement, sublicensing Fees percent

14.00%

Minimum [Member] | Tufts [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement, sublicensing Fees percent

10.00%

Zai Lab (Shanghai) Co., Ltd. [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront license fee payment received and recognized as revenue

$ 0

$ 7,500,000

$ 0

Period of anniversary for first commercial sale of licensed product

11 years

Number of performance obligations | Obligation

2

Deferred revenue

$ 0

Zai Lab (Shanghai) Co., Ltd. [Member] | Paratek Bermuda Ltd [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront license fee payment received and recognized as revenue

7,500,000

Milestone payments on acceptance of an NDA submission

5,000,000

Zai Lab (Shanghai) Co., Ltd. [Member] | Paratek Bermuda Ltd [Member] | Maximum [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Eligible to receive potential regulatory milestone payments

14,000,000

Eligible to receive potential commercial milestone payments

$ 40,500,000

Collaborative Research and License Agreement [Member] | Allergan [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fees received

$ 4,000,000

New Drug Application [Member] | Allergan [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fees received

$ 1,000,000

Collaborative Research and License Agreement Phase 2 Trials [Member] | Allergan [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fees received

$ 2,500,000

Collaborative Research and License Agreement Phase 3 Trials [Member] | Allergan [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fees received

$ 4,000,000

Novartis [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Advance notice to terminate collaboration agreement

60 days

Royalty based on annual net sales

0.25%

Period of patent claim

10 years

Novartis [Member] | Other Long Term Liabilities [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Liability under collaboration agreement

$ 3,600,000

$ 3,600,000

Capital Stock - Additional Info

Capital Stock - Additional Information (Detail) - USD ($)	Jun. 27, 2017	Dec. 12, 2016	Sep. 30, 2015	Feb. 28, 2017	Oct. 31, 2015	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Apr. 30, 2018
Class Of Stock [Line Items]
Proceeds from issuance of common stock						$ 51,516,000	$ 36,859,000
Beneficial owners minimum required percentage of common stock exchanged for warrant						5.00%
Warrants exercisable description						The Warrants are exercisable for a term beginning on the date of issuance and ending on the earlier to occur of five years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the various agreements for the Warrants.
Term of warrants						5 years
Hercules Capital Inc [Member] | Third Amendment [Member]
Class Of Stock [Line Items]
Exercise price of warrants	$ 23.26
Hercules Term Loan [Member]
Class Of Stock [Line Items]
Exercise price of warrants			$ 24.47
Warrants issued to purchase common stock			32,692
Hercules Term Loan [Member] | Second Amendment [Member]
Class Of Stock [Line Items]
Exercise price of warrants		$ 13.46
Warrants issued to purchase common stock		37,148
Hercules Term Loan [Member] | Hercules Technology II, L.P. [Member]
Class Of Stock [Line Items]
Warrants issued to purchase common stock			16,346
Expected life of options (in years)			5 years
Hercules Term Loan [Member] | Hercules Technology II, L.P. [Member] | Second Amendment [Member]
Class Of Stock [Line Items]
Warrants issued to purchase common stock		18,574
Hercules Term Loan [Member] | Hercules Technology III, L.P. [Member]
Class Of Stock [Line Items]
Warrants issued to purchase common stock			16,346
Expected life of options (in years)			5 years
Hercules Term Loan [Member] | Hercules Technology III, L.P. [Member] | Second Amendment [Member]
Class Of Stock [Line Items]
Warrants issued to purchase common stock		18,574
Hercules Term Loan [Member] | Hercules Capital Inc [Member] | Third Amendment [Member]
Class Of Stock [Line Items]
Warrants issued to purchase common stock	5,374
Warrants Expires in 2021 [Member]
Class Of Stock [Line Items]
Warrants outstanding						9,614		9,614
Exercise price of warrants						$ 0.15		$ 0.15
Warrants expiration year						2,021
2015 Sales Agreement [Member] | Cantor [Member]
Class Of Stock [Line Items]
Percentage of proceeds payable as compensation to underwriter					3.00%
Common stock sold, value								$ 50,000,000
2017 Sales Agreement [Member] | Cantor [Member]
Class Of Stock [Line Items]
Percentage of proceeds payable as compensation to underwriter				3.00%
Common stock issued on public offering						96,308
Proceeds from issuance of common stock						$ 1,800,000
Proceeds payable as commission to underwriter						$ 100,000
Maximum [Member] | 2015 Sales Agreement [Member] | Cantor [Member]
Class Of Stock [Line Items]
Common stock for sale					$ 50,000,000
Maximum [Member] | 2017 Sales Agreement [Member] | Cantor [Member]
Class Of Stock [Line Items]
Common stock for sale				$ 50,000,000
Subsequent Event [Member] | 2017 Sales Agreement [Member] | Cantor [Member]
Class Of Stock [Line Items]
Common stock for sale									$ 800,000

Other Accrued Expenses - Schedu

Other Accrued Expenses - Schedule of Other Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued legal costs	$ 485	$ 257
Accrued compensation	1,706	3,403
Intermezzo payable		124
Accrued professional fees	950	953
Accrued contract research	2,200	2,360
Accrued commercial	1,396	911
Accrued other	201	262
Total	$ 6,938	$ 8,270

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Total Assets	$ 135,051	$ 116,307
Liabilities
Total Liabilities	56	71
Contingent Obligations [Member]
Liabilities
Total Liabilities	56	71
Government Agencies [Member]
Assets
Total Assets	800	1,799
U.S. Treasury Securities [Member]
Assets
Total Assets	134,251	114,508
Quoted Prices in Active Markets (Level 1) [Member]
Assets
Total Assets	134,251	114,508
Quoted Prices in Active Markets (Level 1) [Member] | U.S. Treasury Securities [Member]
Assets
Total Assets	134,251	114,508
Significant Other Observable Inputs (Level 2) [Member]
Assets
Total Assets	800	1,799
Significant Other Observable Inputs (Level 2) [Member] | Government Agencies [Member]
Assets
Total Assets	800	1,799
Significant Unobservable Inputs (Level 3) [Member]
Liabilities
Total Liabilities	56	71
Significant Unobservable Inputs (Level 3) [Member] | Contingent Obligations [Member]
Liabilities
Total Liabilities	$ 56	$ 71

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Oct. 28, 2016	Mar. 31, 2018	Mar. 31, 2017
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Changes in fair value of contingent consideration		$ (15,000)	$ (231,000)
Contingent Obligations [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Changes in fair value of contingent consideration		$ (15,000)
Transcept Pharmaceuticals, Inc. [Member] | Royalty Sharing Agreement [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Percentage of royalty income paid for payment obligation	50.00%

Fair Value Measurements - Roll

Fair Value Measurements - Roll Forward of Fair Value of Contingent Obligations (Detail) - Contingent Obligations [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balances	$ 71
Change in fair value	(15)
Ending balances	$ 56

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Included in Company's Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,367	$ 4,044
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	1,460	1,339
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,907	$ 2,705

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Share-based Payment Award, Stock Options, Weighted-Average Valuation Assumptions (Detail) - Employee Stock Option [Member]	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	68.20%	76.40%
Weighted average risk-free interest rate	2.60%	2.00%
Expected dividend yield	0.00%	0.00%
Expected life of options (in years)	5 years 10 months 24 days	5 years 9 months 18 days

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 02, 2018	Jan. 02, 2016	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017	Jun. 09, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			166,150
Compensation cost recognized			$ 4,367	$ 4,044
Unrecognized compensation cost related to unvested share-based arrangements			$ 26,600
Weighted average compensation cost recognition period			2 years 2 months 4 days
PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			15 months
Compensation cost recognized			$ 500
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of annual increase in percentage of share reserved for issuance			The Share Reserve automatically increases on January 1st of each year, for the period commencing on (and including) January 1, 2016 and ending on (and including) January 1, 2025, in an amount equal to 5% of the total number of shares of common stock outstanding on December 31st of the preceding calendar year.
Share based compensation, increase in shares issued	1,397,050
Percentage of shares		5.00%
Total shares available for future issuance			243,185
2015 Plan [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			50,800
2015 Plan [Member] | RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			1,139,370
Time-based vesting period			1 year
Vesting percentage			100.00%
2015 Plan [Member] | PRSUs [Member] | Tranche One[ Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting ratio			0.182
2015 Plan [Member] | PRSUs [Member] | Tranche Two [ Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting ratio			0.364
2015 Plan [Member] | PRSUs [Member] | Tranche Three [ Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting ratio			0.454
2015 Plan [Member] | Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			1 year
2015 Plan [Member] | Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			4 years
2015 Plan [Member] | Directors, Officers, Employees and Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options reserved for future issuance						1,200,000
2015 Plan [Member] | Executives and Employees [Member] | RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			3 years
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			0
2006 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			0
2017 Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares, authorized			139,750
2017 Inducement Plan [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			115,350
2017 Inducement Plan [Member] | RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			34,900
Time-based vesting period			3 years
Vesting percentage			100.00%
2017 Inducement Plan [Member] | PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost recognized			$ 200
2017 Inducement Plan [Member] | Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			1 year
2017 Inducement Plan [Member] | Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time-based vesting period			4 years
2017 Inducement Plan [Member] | Employees Entering into Employment Or Returning to Employment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options reserved for future issuance					550,000
2015 Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted under plan			0
Common stock shares, authorized			106,500
2015 Inducement Plan [Member] | New Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options reserved for future issuance			360,000

Stock-Based Compensation - Sc52

Stock-Based Compensation - Schedule of Share-based Compensation, Stock Options, Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares Outstanding, Beginning Balances	3,608,907
Number of Shares Outstanding, Granted	166,150
Number of Shares Outstanding, Exercised	(28,699)
Number of Shares Outstanding, Cancelled or forfeited	(15,424)
Number of Shares Outstanding, Expired	(40,000)
Number of Shares Outstanding, Ending Balances	3,690,934	3,608,907
Number of Shares Outstanding, Exercisable	2,319,142
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Weighted Average Exercise Price, Beginning Balances	$ 17.01
Weighted Average Exercise Price, Granted	14.52
Weighted Average Exercise Price, Exercised	6.15
Weighted Average Excercise Price, Cancelled or forfeited	15.78
Weighted Average Excercise Price, Expired	29.80
Weighted Average Exercise Price, Ending Balances	16.84	$ 17.01
Weighted Average Exercise Price, Exercisable	$ 16.35
Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted-Average Remaining Contractual Term (in Years)
Options Outstanding, Weighted-Average Remaining Contractual Term (in Years)	7 years 8 months 26 days	7 years 9 months 10 days
Options Exercisable, Weighted-Average Remaining Contractual Term (in Years)	7 years 3 months 7 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value
Options Outstanding, Aggregate Intrinsic Value	$ 5,540	$ 13,311
Options Exercisable, Aggregate Intrinsic Value	$ 5,107

Stock-Based Compensation - Sc53

Stock-Based Compensation - Schedule of Share-based Compensation, RSU, Activity (Detail) - Restricted Stock Units [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested Number of Shares, Beginning Balance | shares	1,167,703
Number of Shares, Granted | shares	1,174,270
Number of Shares, Released | shares	(171,999)
Unvested Number of Shares, Ending Balance | shares	2,169,974
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 18.43
Weighted Average Grant Date Fair Value, Granted | $ / shares	14.31
Weighted Average Grant Date Fair Value, Released | $ / shares	19.30
Unvested Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 16.13

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail)	Apr. 23, 2018USD ($)$ / shares	Apr. 18, 2018USD ($)d$ / shares	Jun. 27, 2017USD ($)$ / sharesshares	Dec. 12, 2016USD ($)$ / sharesshares	Sep. 30, 2015USD ($)$ / sharesshares	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Apr. 17, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of common stock						$ 51,516,000	$ 36,859,000
Current portion of long-term debt obligation						7,607,000
Long-term debt						$ 51,684,000			$ 59,186,000
Subsequent Event [Member]
Debt Instrument [Line Items]
Proceeds from offering notes		$ 158,800,000
Subsequent Event [Member] | 4.75% Convertible Senior Subordinated Notes due 2024 [Member]
Debt Instrument [Line Items]
Loan agreement payment terms	payable on November 1 and May 1 of each year, beginning on November 1, 2018
Loan repayment commencement date	Nov. 1, 2018
Loan maturity date	May 1, 2024
Debt instrument initial conversion rate	62.8931
Debt instrument conversion, principal amount of each note converted	$ 1,000
Debt instrument conversion, conversion price per share | $ / shares	$ 15.90
Debt instrument conversion premium	20.00%
Closing price of the common stock | $ / shares		$ 13.25
Percentage of common stock price		130.00%
Debt instrument, convertible, threshold trading days | d		20
Debt instrument, convertible, threshold consecutive trading days | d		30
Percentage of debt instrument redemption price		100.00%
Debt instrument, debt default, minimum percentage of aggregate principal amount due	25.00%
Proceeds from offering notes		$ 158,800,000
Commissions, fees and other offering expenses		6,200,000
Subsequent Event [Member] | 4.75% Convertible Senior Subordinated Notes due 2024 [Member] | J. Wood Capital Advisors LLC [Member]
Debt Instrument [Line Items]
Principal amount outstanding		5,000,000
Subsequent Event [Member] | Purchase Agreement [Member] | 4.75% Convertible Senior Subordinated Notes due 2024 [Member]
Debt Instrument [Line Items]
Principal amount outstanding		135,000,000
Additional principal amount outstanding		$ 25,000,000
Debt instrument, interest rate		4.75%
Second Amendment [Member]
Debt Instrument [Line Items]
Principal amount outstanding				$ 50,000,000	$ 40,000,000
End of term charge				4.50%
Amortization payment start date				Apr. 1, 2018
Amortization payment end date				Jan. 1, 2019
Additional principal amount outstanding				$ 10,000,000
Fourth Amendment [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Additional principal amount outstanding								$ 2,000,000
Hercules [Member] | Second Amendment [Member]
Debt Instrument [Line Items]
Amendment fee paid				$ 400,000
Hercules Term Loan [Member]
Debt Instrument [Line Items]
Principal amount outstanding					40,000,000
Initial principal amount drawn					20,000,000
Remaining available amount under loan agreement					20,000,000
Minimum incremental option to withdraw on loan					$ 10,000,000
Loan agreement description						Under the Hercules Loan Agreement, Hercules provided the Company with access to term loans with an aggregate principal amount of up to $40.0 million, or collectively, the Term Loan. The Company initially drew a principal amount of $20.0 million, which was funded on September 30, 2015. The remaining $20.0 million under the Hercules Loan Agreement was available to be drawn at the Company’s option in minimum increments of $10.0 million through December 31, 2016, or the Draw Period.
Loan agreement payment terms						The Term Loan was repayable in monthly installments commencing on April 1, 2018 through maturity on September 1, 2020.
Loan repayment commencement date					Apr. 1, 2018
Loan maturity date					Sep. 1, 2020
Loan interest rate description						The interest rate was equal to the greater of (i) 8.5%, or (ii) the sum of 8.5%, plus the “prime rate” as reported in The Wall Street Journal minus 5.75% per annum.
Basis spread on prime rate					5.75%
End of term charge					4.50%
Additional interest rate on default					5.00%
Minimum subordinated debt for event of default					$ 1,000,000
Debt issuance costs					$ 511,000
Warrants issued to purchase common stock | shares					32,692
Warrants exercise price | $ / shares					$ 24.47
Fair value of warrants					$ 288,000
Aggregate amount of warrant fair and fees paid					572,000
Cost allocated to debt discount amortized as additional interest expense					208,000
Cost allocated to prepaid expenses and are being amortized					364,000
Current portion of long-term debt obligation						$ 7,600,000
Current portion of long-term debt obligation debt discount, net						400,000
Long-term debt						51,700,000
Long-term debt obligation debt discount, net						$ 300,000
Hercules Term Loan [Member] | Second Amendment [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares				37,148
Warrants exercise price | $ / shares				$ 13.46
Hercules Term Loan [Member] | Third Amendment [Member]
Debt Instrument [Line Items]
Principal amount outstanding			$ 60,000,000	$ 50,000,000
Initial principal amount drawn			$ 10,000,000	$ 20,000,000	$ 20,000,000
End of term charge			2.25%	4.50%		2.25%
Amortization payment start date			Jan. 1, 2019
Amortization payment end date			Jan. 1, 2020
Additional principal amount outstanding			$ 10,000,000
Percentage of prepayment						1.00%
Hercules Term Loan [Member] | Third Amendment [Member] | Prior to April 1, 2019 [Member]
Debt Instrument [Line Items]
Percentage of prepayment						2.00%
Hercules Term Loan [Member] | Third Amendment [Member] | On Or After April 1, 2019 [Member]
Debt Instrument [Line Items]
Percentage of prepayment						0.00%
Hercules Term Loan [Member] | Hercules [Member]
Debt Instrument [Line Items]
Rights to purchase common stock, exercised | shares					44,782
Proceeds from issuance of common stock					$ 1,000,000
Hercules Term Loan [Member] | Hercules [Member] | Third Amendment [Member]
Debt Instrument [Line Items]
Amendment fee paid			$ 100,000
Hercules Term Loan [Member] | Hercules Technology II, L.P. [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares					16,346
Hercules Term Loan [Member] | Hercules Technology II, L.P. [Member] | Second Amendment [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares				18,574
Hercules Term Loan [Member] | Hercules Technology III, L.P. [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares					16,346
Hercules Term Loan [Member] | Hercules Technology III, L.P. [Member] | Second Amendment [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares				18,574
Hercules Term Loan [Member] | Hercules Capital Inc [Member] | Third Amendment [Member]
Debt Instrument [Line Items]
Warrants issued to purchase common stock | shares			5,374
Additional warrants exercisable | shares			5,374
Additional warrants exercise price | $ / shares			$ 23.26
Additional warrants exercisable term			5 years
Hercules Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Loan interest rate					8.50%
Hercules Term Loan [Member] | Maximum [Member] | Hercules [Member]
Debt Instrument [Line Items]
Rights granted in subsequent sales and issuance of equity securities					$ 2,000,000
Convertible Debt [Member] | Fourth Amendment [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Principal amount outstanding								$ 172,500,000

Long-Term Debt - Schedule of Fu

Long-Term Debt - Schedule of Future Principal Payments (Detail) - Hercules Term Loan [Member] $ in Thousands	Mar. 31, 2018USD ($)
Debt Instrument [Line Items]
2,019	$ 33,140
2,020	26,860
Total	$ 60,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provision for income taxes	$ 0	$ 0
U.S. Corporate tax rate				35.00%
Provisional income tax expense (benefit)	$ 0
Scenario Plan [Member]
Income Taxes [Line Items]
U.S. Corporate tax rate			21.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Sep. 28, 2016	Mar. 31, 2018
131 Patent [Member]
Operating Leased Assets [Line Items]
Patent term adjustment	1038 days
Patent expiration period	Mar. 26, 2029
Boston [Member]
Operating Leased Assets [Line Items]
Lease expiration period		2,021
King of Prussia [Member]
Operating Leased Assets [Line Items]
Lease expiration period		2,024

Commitments and Contingencies58

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Operating Leases (Detail) $ in Thousands	Mar. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2018	$ 869
2,019	1,156
2,020	1,178
2,021	964
2,022	508
2023 and Thereafter	914
Total	$ 5,589