Kindred Biosciences (KIN) 10-K 6 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Kindred Biosciences, Inc.
Entity Central Index Key	1,561,743
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding (in shares)		38,855,154
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Public Float			$ 269

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 56,302	$ 34,813
Short-term investments	17,630	46,207
Accounts receivable	903	0
Inventories	3,570	0
Prepaid expenses and other	1,664	797
Total current assets	80,069	81,817
Property and equipment, net	26,343	7,457
Long-term investments	0	1,499
Other assets	70	49
Total assets	106,482	90,822
Current liabilities:
Accounts payable	3,576	1,439
Accrued compensation	3,436	2,688
Accrued liabilities	8,169	1,900
Total current liabilities	15,181	6,027
Long-term liability	94	115
Total liabilities	15,275	6,142
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock; $0.0001 par value; 100,000,000 shares authorized; 33,948,254 shares and 28,182,563 shares issued and outstanding at December 31, 2018 and 2017, respectively	3	3
Additional paid-in capital	252,885	196,688
Accumulated other comprehensive loss	(11)	(31)
Accumulated deficit	(161,670)	(111,980)
Total stockholders’ equity	91,207	84,680
Total liabilities and stockholders’ equity	$ 106,482	$ 90,822

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value (USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	33,948,254	28,182,563
Common stock, shares outstanding (in shares)	33,948,254	28,182,563

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net product revenues	$ 1,326	$ 640	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 1,966	$ 0	$ 0
Operating expenses:
Cost of product revenues	214	110	0	0	0	0	0	0		324	0	0
Research and development	7,756	7,477	5,820	5,346	5,142	4,877	3,866	3,780		26,399	17,665	13,861
General and administrative	9,219	6,608	5,770	4,902	4,820	3,269	3,056	2,843		26,499	13,988	8,308
Restructuring costs									$ 655	0	0	655
Total operating expenses	17,189	14,195	11,590	10,248	9,962	8,146	6,922	6,623		53,222	31,653	22,824
Loss from operations	(15,863)	(13,555)	(11,590)	(10,248)	(9,962)	(8,146)	(6,922)	(6,623)		(51,256)	(31,653)	(22,824)
Interest and other income, net	422	518	349	277	232	256	155	131		1,566	774	325
Net loss	$ (15,441)	$ (13,037)	$ (11,241)	$ (9,971)	$ (9,730)	$ (7,890)	$ (6,767)	$ (6,492)		(49,690)	(30,879)	(22,499)
Change in unrealized gains on available-for-sale securities										20	0	19
Comprehensive loss										$ (49,670)	$ (30,879)	$ (22,480)
Net loss per share, basic and diluted (USD per share)	$ (0.46)	$ (0.39)	$ (0.39)	$ (0.36)	$ (0.35)	$ (0.29)	$ (0.29)	$ (0.30)		$ (1.60)	$ (1.23)	$ (1.13)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	33,708	33,601	28,619	27,986	27,915	27,400	23,409	21,516		31,001	25,084	19,873

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	At-the-Market Offering	At-the-Market OfferingCommon Stock	At-the-Market OfferingAdditional Paid-In Capital	Public Offering	Public OfferingCommon Stock	Public OfferingAdditional Paid-In Capital
Beginning balance (in shares) at Dec. 31, 2015		19,836,000
Beginning balance at Dec. 31, 2015	$ 76,371	$ 2	$ 135,021	$ (50)	$ (58,602)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(22,499)				(22,499)
Change in unrealized losses on available-for-sale securities	19			19
Comprehensive loss	(22,480)
Stock-based compensation	$ 3,627		3,627
Exercise of common stock options (in shares)	39,501	40,000
Exercise of common stock options	$ 23		23
Common stock issued under ESPP (in shares)		40,429
Common stock issued under ESPP	139		139
Ending balance (in shares) at Dec. 31, 2016		19,916,000
Ending balance at Dec. 31, 2016	57,680	$ 2	138,810	(31)	(81,101)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(30,879)				(30,879)
Change in unrealized losses on available-for-sale securities	0
Comprehensive loss	(30,879)
Restricted stock awards, unvested (in shares)		250,000
Restricted stock awards, unvested	0
Stock-based compensation	$ 5,207		5,207
Exercise of common stock options (in shares)	156,927	157,000
Exercise of common stock options	$ 311	$ 0	311
Stock issued during period (in shares)							4,502,000			3,314,000
Stock issued during period						$ 28,962	$ 1	$ 28,961	$ 23,198		$ 23,198
Common stock issued under ESPP (in shares)		43,561
Common stock issued under ESPP	$ 201		201
Ending balance (in shares) at Dec. 31, 2017	28,182,563	28,183,000
Ending balance at Dec. 31, 2017	$ 84,680	$ 3	196,688	(31)	(111,980)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(49,690)				(49,690)
Change in unrealized losses on available-for-sale securities	20			20
Comprehensive loss	(49,670)
Shares withheld related to net share settlement of equity awards (in shares)		(27,000)
Shares withheld related to net share settlement of equity awards	(247)		(247)
Stock-based compensation	$ 6,277		6,277
Exercise of common stock options (in shares)	242,031	231,000
Exercise of common stock options	$ 635		635
Stock issued during period (in shares)							188,000			5,326,000
Stock issued during period						$ 1,758		$ 1,758	$ 47,422		$ 47,422
Common stock issued under ESPP (in shares)		46,850
Common stock issued under ESPP	$ 352		352
Ending balance (in shares) at Dec. 31, 2018	33,948,254	33,948,000
Ending balance at Dec. 31, 2018	$ 91,207	$ 3	$ 252,885	$ (11)	$ (161,670)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - Common Stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
At-the-Market Offering
Payments of stock issuance costs	$ 145	$ 1,038
Public Offering
Payments of stock issuance costs	$ 3,178	$ 1,657

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net loss	$ (49,690)	$ (30,879)	$ (22,499)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,277	5,207	3,627
Depreciation and amortization expense	805	475	155
Loss on disposal of property and equipment	34	27	3
Amortization of (discount) premium on marketable securities	(179)
Amortization of (discount) premium on marketable securities		162	274
Changes in operating assets and liabilities:
Accounts receivable	(903)	0	0
Inventories	(3,570)	0	0
Prepaid expenses and other	(867)	485	(570)
Other assets	(21)	(3)	(16)
Accounts payable	277	1,280	(710)
Accrued liabilities and accrued compensation	2,802	1,368	955
Net cash used in operating activities	(45,035)	(21,878)	(18,781)
Cash Flows from Investing Activities
Purchases of investments	(25,100)	(70,110)	(72,047)
Sales of investments	800	4,897	0
Maturities of investments	54,575	68,465	78,313
Purchases of property and equipment	(13,919)	(5,920)	(952)
Proceeds from sale of property and equipment	248	0	0
Net cash provided by (used in) investing activities	16,604	(2,668)	5,314
Cash Flows from Financing Activities
Exercise of stock options and purchase of ESPP shares	987	512	162
Payment of restricted stock awards tax liability on net settlement	(247)	0	0
Net proceeds from sales of common stock	49,180	52,160	0
Net cash provided by financing activities	49,920	52,672	162
Net change in cash and cash equivalents	21,489	28,126	(13,305)
Cash and cash equivalents at beginning of year	34,813	6,687	19,992
Cash and cash equivalents at end of year	56,302	34,813	6,687
Supplemental disclosure of non-cash financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 6,205	$ 266	$ 670

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Kindred Biosciences, Inc. (“we”, "us" or "our") was incorporated on September 25, 2012 (inception) in the State of Delaware. On April 25, 2016, we filed a Certificate of Incorporation with the State of Delaware for a wholly owned subsidiary, KindredBio Equine, Inc. ("Subsidiary"). The Subsidiary has one class of capital stock which is designated common stock, $0.0001 par value per share. The authorized number of shares of common stock for the Subsidiary is 1,000 . We are a commercial-stage biopharmaceutical company focused on saving and improving the lives of pets. Our activities since inception have consisted principally of raising capital, establishing facilities, recruiting management and technical staff and performing research and development and advancing our product candidates seeking regulatory approval. Our headquarters are in Burlingame, California. We are subject to risks common to companies in the biotechnology and pharmaceutical industries. There can be no assurance that our research and development will be successfully completed, that adequate protection for our technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. We operate in an environment of substantial competition from other animal health companies. In addition, we are dependent upon the services of our employees and consultants, as well as third-party contract research organizations and manufacturers. Liquidity We have incurred losses and negative cash flows from operations and had an accumulated deficit of $161.7 million as of December 31, 2018 . We expect to continue to incur losses and negative cash flows, which will increase significantly from historical levels as we expand our product development activities, seek regulatory approvals for our product candidates, establish a biologics manufacturing capability, and commercialize approved products. We might require additional capital until such time as we can generate operating revenues in excess of operating expenses. To date, we have been funded primarily through sales of convertible preferred stock and the sale of our common stock in our initial public offering in December 2013, in which we raised approximately $67.0 million , net of offering costs. In April 2014, we completed a follow-on public offering of common stock, resulting in net proceeds of approximately $58.1 million . In 2017, we completed the sale of common stock under an At Market Issuance Sales Agreement, or the Sales Agreement as well as an underwritten public offering, resulting in net proceeds of approximately $29.0 million and $23.2 million , respectively. In May 2018, we entered into another Sales Agreement, but terminated the Sales Agreement in June 2018 after having sold 188,100 shares, representing gross proceeds of approximately $1.9 million . Net proceeds, after deducting commission, fees and offering costs, were approximately $1.8 million . Also, in June 2018 we completed a public offering of 5,326,314 shares of common stock, which included the underwriters' option to purchase additional shares, at a public offering price of $9.50 per share for total gross proceeds of approximately $50.6 million . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $47.4 million . In January 2019, we completed a public offering of 4,847,250 shares of common stock, which includes the exercise in full by the underwriters' option to purchase 632,250 additional shares of the Company’s common stock, at a public offering price of $9.50 per share for total gross proceeds of approximately $46.0 million . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $43.1 million . As of December 31, 2018, we believe our cash, cash equivalents and investments in available-for-sale securities of approximately $73.9 million and together with the $43.1 million raised in January 2019, are sufficient to fund our planned operations for at least the next 24 months. If we require additional funding for operations, we may seek such funding through public or private equity or debt financings or other sources, such as corporate collaborations and licensing arrangements. We may not be able to obtain financing on acceptable terms, or at all, and we may not be able to enter into corporate collaborations or licensing arrangements. The terms of any financing may result in dilution or otherwise adversely affect the holdings or the rights of our stockholders. If we are unable to obtain funding, we could be forced to delay, reduce or eliminate our research and development programs or commercialization efforts, which could adversely affect our business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of the Company and its wholly owned Subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements and related disclosures in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting periods. Estimates are based historical experiences or on forecasts, including information received from third parties and other assumptions that the Company believes are reasonable under the circumstances. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from those estimates. Cash, Cash Equivalents and Investments We consider all highly liquid investments purchased with an original maturity of three months or less at the date of acquisition to be cash equivalents. Debt securities with original maturities greater than three months and remaining maturities less than one year are classified as short-term investments. We classify all investments as available-for-sale. Available-for-sale securities are carried at estimated fair value, with accumulated unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in the accompanying consolidated balance sheets. Realized gains or losses on the sale of investments are determined on a specific identification method, and such gains and losses are reflected as a component of interest and other income, net in the accompanying consolidated statements of operations and comprehensive loss. Marketable securities investments are evaluated periodically for impairment. We take into account general market conditions, changes in the economic environment as well as specific investment attributes, such as credit downgrade or illiquidity for each investment, the expected cash flows from the securities, our intent to sell the securities and whether or not we will be required to sell the securities before the recovery of their amortized cost, to estimate the fair value of our investments and to determine whether impairment is other than temporary. If it is determined that a decline in fair value of any investment is other than temporary, then the unrealized loss related to credit risk would be included in interest and other income, net. Concentration of Credit Risk and of Significant Suppliers and Customers Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents and investments. From time to time, we maintain cash and cash equivalent balances in excess of amounts insured by the Federal Deposit Insurance Corporation (“FDIC”) and the Securities Investor Protection Corporation ("SIPC"). Primarily all of our cash, cash equivalents and investments at December 31, 2018 were in excess of amounts insured by the FDIC and SIPC. We do not believe that we are subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. We are dependent on third-party manufacturers to supply products for research and development activities in our programs. In particular, we rely on a small number of manufacturers to supply us with our requirements for the active pharmaceutical ingredients, or API, and formulated drugs related to some of these programs. These programs would be adversely affected by a significant interruption in the supply of API. We are also dependent on a combination of national and regional distributors for our product sales of Mirataz. See Note 3. Fair Value Measurements We use the provisions of Accounting Standards Codification ("ASC") 820, “ Fair Value Measurements and Disclosure", to determine the fair values of our financial and nonfinancial assets and liabilities where applicable. ASC 820 defines fair value, establishes a framework for measuring fair value in U.S. GAAP and expands disclosure about fair value measurements. The objective of fair value measurement is to determine the price that would be received to sell the asset or paid to transfer the liability (an exit price) in an orderly transaction between market participants at the measurement date. ASC 820 emphasizes that fair value is a market-based measurement, not an entity-specific measurement, and that market participant assumptions include assumptions about risk and effect of a restriction on the sale or use of an asset. To increase consistency and comparability in fair value measurement and related disclosures, ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels: (1) Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date; (2) Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly through corroboration with observable market data; and (3) Level 3 inputs are unobservable inputs for the asset or liability that reflect the reporting entity’s own assumptions about risk and the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. Government agency notes, corporate notes and commercial papers are recorded at their estimated fair value. Since these available-for-sale securities generally have market prices from multiple sources and it can be difficult to select the best individual price directly from the quoted prices in the active markets, we use Level 2 inputs for the valuation of these securities. Using the Level 2 inputs, a “consensus price” or a weighted average price for each of these securities can be derived from a distribution-curve-based algorithm which includes market prices obtained from a variety of industrial standard data providers (e.g. Bloomberg), security master files from large financial institutions, and other third-party sources. The carrying amount of financial instruments, including cash, accounts payable and accrued liabilities approximate fair value due to the short maturities of these financial instruments. Financial assets, which consist of money market funds and available-for-sale securities, are measured at fair value on a recurring basis (see Note 4). Property and Equipment On June 21, 2017, we entered into a purchase agreement with Strategic Veterinary Pharmaceuticals, Inc. ("SVP") for the purchase of an approximately 180,000 sq. ft. biologics plant ("the Plant") with clean rooms, utility, equipment, and related quality documentation suitable for small molecule and biologics manufacturing, that is located in Elwood, Kansas. The purchase was finalized on August 7, 2017 upon completion of the diligence period and satisfaction of the conditions of escrow. The Plant was purchased for $3,750,000 , which includes approximately eight acres of land located at 1411 Oak Street, Elwood, Kansas, all improvements located at the Plant, and all personal property and intangible property owned by SVP and located at the Plant or used in connection with the operation of the Plant. Property and equipment are stated at cost less accumulated depreciation and amortization. We calculate depreciation using the straight-line method over the estimated useful lives of the assets, which range from two to five years for furniture, fixtures, lab and computer equipment and software, and fifteen to thirty-nine years for land improvements and real property. Land and assets held within construction in progress are not depreciated. Construction in progress is related to the construction or development of property and equipment that have not yet been placed in service for their intended use. Expenditures for repairs and maintenance of assets are charged to expense as incurred. We amortize leasehold improvements using the straight-line method over the estimated useful lives of the respective assets or the lease term, whichever is shorter. Upon retirement or sale, the cost and related accumulated depreciation and amortization of assets disposed of are removed from the accounts and any resulting gain or loss is included in other income/expense. Licenses The costs incurred for the rights to use licensed technologies in the research and development process, including licensing fees and milestone payments, are charged to research and development expense as incurred in situations where we have not identified an alternative future use for the acquired rights, and are capitalized in situations where we have identified an alternative future use. No costs associated with the use of licensed technologies have been capitalized to date. Impairment of Long-Lived Assets We review long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that we consider in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, we compare forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. To date, we have not recorded any impairment losses on long-lived assets. Revenue Recognition We adopted ASC Topic 606 (“ASC 606”), "Revenue from Contracts with Customers" in the first quarter of our fiscal year that began on January 1, 2018. This new standard replaced the previous revenue recognition guidance in U.S. GAAP. No prior period adjustments were needed as our first commercial shipments began in July 2018. Our revenue consists of product revenue resulting from the sale of Mirataz for the management of weight loss in cats. We account for a contract with a customer when there is a legally enforceable contract between us and our customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. Our customers could either be distributors who subsequently resell our products to third parties such as veterinarians, clinics or animal hospitals or the third parties themselves. We use a contract manufacturer to produce Mirataz and a third-party logistics vendor to process and fulfill orders. We concluded we are the principal in our sales because we control access to services rendered by both vendors and direct their activities. We have no significant obligations to distributors to generate pull-through sales. In accordance with ASC 606, we applied the following steps to recognize revenue for the sale of Mirataz that reflects the consideration to which we expect to be entitled to receive in exchange for the promised goods: 1. Identify the contract with a customer A contract with a customer exists when we enter into an enforceable contract with a customer. These contracts define each party's rights, payment terms and other contractual terms and conditions of the sale. We apply judgment in determining the customer’s ability and intention to pay, which is based on published credit and financial information pertaining to the customer. 2. Identify the performance obligations in the contract Our product in a given purchase order is delivered at the same time and we do not separate an individual order into separate performance obligations. We have concluded the sale of finished goods and related shipping and handling are accounted for as a single performance obligation as there are no other promises to deliver goods beyond what is specified in each accepted customer order. 3. Determine the transaction price The transaction price is determined based on the consideration to which we will be entitled to receive in exchange for transferring goods to the customer, typically a fixed consideration in our contractual agreements. 4. Allocate the transaction price to the performance obligations The transaction price is allocated entirely to the performance obligation to provide pharmaceutical products. The nature of the promises/obligations under our contracts is to transfer a distinct good. Accordingly, because a single performance obligation exists, no allocation of the transaction price is necessary. 5. Determine the satisfaction of performance obligation Revenue is recognized when control of the finished goods is transferred to the customer, net of applicable reserves for variable consideration. Control of the finished goods is transferred at a point in time, upon delivery to the customer. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price, which includes estimates of variable consideration for which reserves are established. Components of variable consideration include product returns, allowances and discounts. These estimates take into consideration a range of possible outcomes for the expected value (probability-weighted estimate) or relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the respective underlying contracts. The amount of variable consideration included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized where the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect net product revenues and earnings in the period such variances become known. Product Returns Consistent with the industry practice, we generally offer customers a limited right of return of damaged or expired product that has been purchased directly from us. Our return policy generally allows customers to receive credit for expired products within 90 days after the product’s expiration date. We estimate the amount of our product revenues that may be returned by our customers and record these estimates as a reduction of product revenues in the period the related product revenues are recognized, as well as within accrued liabilities, in the consolidated balance sheets. We currently estimate product return liabilities using probability-weighted available industry data and data provided by the our distributors such as the inventories remaining in the distribution channel. To-date, we have no returns and believe that returns of our product in future periods will be minimal. We do not record a return asset associated with the returned damaged or expired goods due to such asset is deemed to be fully impaired at the time of product return. Sales Discounts and Allowances We compensate our distributors for sales order management, data and distribution and other services through sales discounts and allowances. However, such services are not distinct from our sale of products to distributors and, therefore, these discounts and allowances are recorded as a reduction of product revenues in the statements of operations, as well as a reduction to accounts receivable in the consolidated balance sheets. Practical Expedients and Exemptions We generally expense sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses. Cost of Product Revenues Cost of product revenues consists primarily of the cost of direct materials, direct labor and overhead costs associated with manufacturing, inbound shipping and other third-party logistics costs. Inventories We value inventory at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on a first-in, first-out method. We analyze our inventory levels quarterly and write down inventory subject to expire in excess of expected requirements, or that has a cost basis in excess of its expected net realizable value. These inventory related costs are recognized as cost of product revenues on the accompanying Consolidated Statements of Operations and Comprehensive Loss. Currently our inventory consists of finished goods only. Research and Development Costs All costs of research and development are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, stock-based compensation expense, fees paid to consultants, outside service providers, professional services, travel costs and materials used in clinical trials and research and development. Patent Costs All patent-related costs incurred in connection with filing patent applications are recorded in research and development expenses when incurred, as recoverability of such expenditures is uncertain. Stock-Based Compensation Our stock-based compensation plan (see Note 9) provides for the grant of stock options, restricted common stock, restricted stock units and stock appreciation rights. The estimated fair values of employee stock option grants are determined as of the date of grant using the Black-Scholes option pricing model. This method incorporates the fair value of our common stock at the date of each grant and various assumptions such as the risk-free interest rate, expected volatility based on historic volatility of Kindred Biosciences own stock prices, and expected dividend yield, and expected term of the options. The estimated fair values of restricted stock awards are determined based on the fair value of our common stock on the date of grant. The estimated fair values of stock-based awards, including the effect of estimated forfeitures, are expensed over the requisite service period, which is generally the awards’ vesting period. We classify stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified. Our accounting policy for equity instruments issued to consultants and vendors in exchange for goods and services follows Financial Accounting Standards Board ("FASB") guidance. All transactions in which goods or services are the consideration received for the issuance of equity instruments are accounted for based on the fair value of the consideration received or the fair value of the equity instrument issued, whichever is more reliably measurable. The measurement date of the fair value of the equity instrument issued is the earlier of the date on which the counterparty’s performance is complete or the date at which a commitment for performance is reached. Non-employee grants of stock-based compensation, except those grants to non-employee, shareholder-approved Board Members, were previously valued under ASC 505-50 "Equity-Based Payments to Non-Employees". In Q2 2018, we adopted ASU 2018-07 "Compensation - Stock Compensation (Topic 718) - Improvements to Non-Employee Share-Based Payment Accounting" and non-employee grants are now valued in the same manner as employee grants. Income Taxes We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in our tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. We assess the likelihood that our deferred tax assets will be recovered from future taxable income and, to the extent we believe, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. We account for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. Comprehensive Loss Our comprehensive loss includes the change in unrealized gains or losses on available-for-sale securities. The cumulative amount of gains or losses is reflected as a separate component of stockholders' equity in the accompanying consolidated balance sheets as accumulated other comprehensive loss. Segment Data We manage our operations as a single segment for the purposes of assessing performance and making operating decisions. We are a veterinary biotechnology company focusing on developing therapies for pets. Our chief operating decision maker is our Chief Executive Officer. All assets are held in the United States. Basic and Diluted Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders for the period by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders for the period by the weighted average number of common shares, including potential dilutive shares of common stock assuming the dilutive effect of potentially dilutive securities. For periods in which we have reported a net loss, diluted net loss per common share is the same as basic net loss per common share, since the impact of the potentially dilutive securities would be anti-dilutive to the calculation of net loss per common share (see Note 13). Recently Issued Accounting Pronouncements In February 2016, Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, "Leases (Topic 842)", requiring organizations that lease assets—referred to as “lessees”—to recognize on the consolidated balance sheet the assets and liabilities for the rights and obligations created by those leases. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. The ASU on leases will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. In July 2018, the FASB issued ASU No. 2018-10, "Codification Improvements to Topic 842, Leases", which affects narrow aspects of the guidance issued in ASU No. 2016-02. The amendments in this ASU related to transition do not include amendments from proposed ASU, Leases (Topic 842): Targeted Improvements, specific to a new and optional transition method to adopt the new lease requirements in ASU 2016-02. For entities that have not adopted Topic 842, the effective date and transition requirements will be the same as the effective date and transition requirements in Topic 842. In July 2018, the FASB issued ASU No. 2018-11, "Targeted Improvements to Topic 842, Leases". This update provides another transition method in addition to the existing transition method by allowing entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. For entities that have not adopted Topic 842, the effective date and transition requirements will be the same as the effective date and transition requirements in Topic 842. We adopted ASC 842 as of January 1, 2019. In preparation of adopting ASC 842, we have purchased a special lease software and also implemented additional internal controls to enable future preparation of financial information in accordance with ASC 842. We believe the largest impact will be on the consolidated balance sheets for the accounting of facilities-related leases, which represent a majority of the operating leases the Company has entered into. These leases will be recognized under the new lease standard as ROU (Right of Use) assets and operating lease liabilities. We will also be required to provide expanded disclosures for the leasing arrangements. As of December 31, 2018 , we had $2.2 million of undiscounted future minimum operating lease commitments that are not recognized on our consolidated balance sheets under the new standard. We are still in the process of finalizing the evaluations of the effect of ASU 842 on our consolidated financial statements and disclosures and will finalize our accounting assessment and quantitative impact of the adoption in the first quarter of 2019. In July 2018, the FASB issued ASU No. 2018-09, "Codification Improvements", and the amendments in this ASU affect a wide variety of Topics in the Codification. It applies to all reporting entities within the scope of the affected accounting guidance. It will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have adopted the new guidance and the impact of this standard does not have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820)", which changes to disclosure requirements for fair value measurement. The amendments of this update modify the disclosure requirements on fair value measurements about Topic 820. It applies to all reporting entities within the scope of the affected accounting guidance. It will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are currently evaluating the new guidance and have not determined the impact this standard may have on our consolidated financial statements. We do not believe there are any other recently issued standards not yet effective that will have a material impact on our consolidated financial statements when the standards become effective.

Revenue and Cost of Product Rev

Revenue and Cost of Product Revenues	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue and Cost of Product Revenues	Revenues and Cost of Product Revenues We adopted ASC 606 in the first quarter of our fiscal year that began on January 1, 2018. This new standard replaced the previous revenue recognition guidance in U.S. GAAP. No prior period adjustments were needed as our first commercial shipments began in July 2018. Our revenues consist of product revenues resulting from the sale of Mirataz for the management of weight loss in cats. We account for a contract with a customer when there is a legally enforceable contract between us and our customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. Our revenues are measured based on the consideration specified in the contract with each customer, net of product returns, discounts and allowances. The following table presents revenues and cost of product revenues for the year ended December 31, 2018 (there were no revenues recognized in previous years) (in thousands): Year Ended December 31, 2018 Gross product revenues $ 2,027 Less allowance for product returns (61 ) Net product revenues 1,966 Cost of product revenues (324 ) Gross Profit $ 1,642 Concentrations of credit risk Our revenue was generated entirely from sales within the United States. Our product sales to four large distributors, namely MWI, Henry Schein, Patterson and Midwest each accounted for more than 10% of total revenues for the year ended December 31, 2018. On a combined basis, in 2018, these distributors accounted for approximately 91% of our product sales in the United States. Product returns Our return policy generally allows customers to receive credit for expired products within 90 days after the product’s expiration date. We currently estimate product return liabilities of 3% of gross revenue using probability-weighted available industry data and data provided by our distributors such as the inventories remaining in the distribution channel. Adjustments will be made in the future if actual results vary from our estimates. Accounts receivable and allowance for doubtful accounts Accounts receivable are stated at their carrying values, net of any allowances for doubtful accounts. Accounts receivable consist primarily of amounts due from distributors, for which collection is probable based on the customer's intent and ability to pay. Receivables are evaluated for collection probability on a regular basis and an allowance for doubtful accounts is recorded, if necessary. We have no allowance for doubtful accounts as of December 31, 2018 as our analysis did not uncover any collection risks.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We measure certain financial assets at fair value on a recurring basis, including cash equivalents and available-for-sale securities. The fair value of these financial assets was determined based on a three-tier fair value hierarchy as described in Note 2, which prioritizes the inputs used in measuring fair value. The following table presents information about our financial assets that are measured at fair value on a recurring basis as of December 31, 2018 and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: (In thousands) Fair Value Measurements as of December 31, 2018 Description Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Cash equivalents: Money market funds $ 1,276 $ 1,276 $ — $ — U.S. treasury bills 500 500 — — Commercial paper 45,332 — 45,332 — U.S. treasury bonds and notes 7,949 — 7,949 — Short-term investments: Commercial paper 5,353 — 5,353 — Corporate notes 12,277 — 12,277 — $ 72,687 $ 1,776 $ 70,911 $ — The following table presents information about our financial assets that are measured at fair value on a recurring basis as of December 31, 2017 and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: (In thousands) Fair Value Measurements as of December 31, 2017 Description Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Cash equivalents: Money market funds $ 801 $ 801 $ — $ — Commercial paper 31,977 — 31,977 — Corporate notes 1,500 — 1,500 — Short-term investments: Commercial paper 22,052 — 22,052 — US government agency notes 6,746 — 6,746 — U.S. treasury bonds and notes 3,482 3,482 — — Corporate notes 13,927 — 13,927 — Long-term investments: Corporate notes 1,499 — 1,499 — $ 81,984 $ 4,283 $ 77,701 $ — There were no other transfers of assets between Level 1, Level 2 or Level 3 of the fair value hierarchy during the years ended December 31, 2018 and 2017 . At December 31, 2018 and 2017 , we did not have any financial liabilities which were measured at fair value on a recurring basis.

Investments

Investments	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The following tables summarize our investments in available-for-sale securities by significant investment category reported as short-term or long-term investments as of December 31, 2018 and 2017 (in thousands): December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: Commercial paper $ 5,353 $ — $ — $ 5,353 Corporate notes 12,288 — (11 ) 12,277 17,641 — (11 ) 17,630 Total available-for-sale investments $ 17,641 $ — $ (11 ) $ 17,630 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: Commercial paper $ 22,052 $ — $ — $ 22,052 U.S. government agency notes 6,750 — (4 ) 6,746 U.S. treasury bonds and notes 3,483 — (1 ) 3,482 Corporate notes 13,946 — (19 ) 13,927 46,231 — (24 ) 46,207 Long-term investments: Corporate notes 1,506 — (7 ) 1,499 Total available-for-sale investments $ 47,737 $ — $ (31 ) $ 47,706 The following table summarizes the contractual maturities of our available-for-sale securities at December 31, 2018 (in thousands): Amortized Cost Fair Value Mature in less than one year $ 17,641 $ 17,630 Mature in one year or more $ — $ —

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment, Net [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment consisted of the following: As of December 31, (In thousands) 2018 2017 Computer and lab equipment $ 4,923 $ 2,303 Furniture and fixtures 65 46 Leasehold improvements 930 930 Construction-in-process 21,999 4,969 Total 27,917 8,248 Less accumulated depreciation and amortization (1,574 ) (791) Property and equipment, net $ 26,343 $ 7,457 Construction-in-process is comprised of land, land improvements, building, building improvement and equipment that have not been put into service for their intended use as of December 31, 2018 . As disclosed in Note 2, the Plant was purchased for $3,750,000 , which includes approximately eight acres of land, all improvements located at the Plant, and all personal property and intangible property located at the Plant or used in connection with the operation of the Plant. We incurred approximately $18,249,000 in building renovation and construction costs as well as additional manufacturing and lab equipment that have not been put into service, resulting in a construction-in-process balance of $21,999,000 at December 31, 2018 . Depreciation and amortization expense was $805,000 , $475,000 and $155,000 for the years ended December 31, 2018 , 2017 and 2016 , respectively.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following as of December 31, 2018 and 2017 : (In thousands) December 31, 2018 December 31, 2017 Accrued consulting $ 627 $ 335 Accrued research and development costs 2,509 919 Accrued other 5,012 646 Deferred rent 115 115 8,263 2,015 Less current portion (8,169 ) (1,900 ) Long-term liability (deferred rent) $ 94 $ 115

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Preferred Stock Our Certificate of Incorporation, as amended, authorizes us to issue 10,000,000 shares of $0.0001 par value preferred stock. At December 31, 2018, 100,000 unissued shares of our preferred stock are designated as Series A Preferred Stock, and the remaining 9,900,000 unissued shares of our preferred stock are undesignated. Common Stock Our Certificate of Incorporation, as amended and restated, authorizes us to issue 100,000,000 shares of $0.0001 par value common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of our stockholders, provided, however, that, except as otherwise required by law, holders of common stock shall not be entitled to vote on any amendment to the Certificate of Incorporation that relates solely to the terms of one or more outstanding shares of preferred stock if the holders of such affected series are entitled, either separately or together with the holders of one or more other series, to vote thereon pursuant to the Certificate of Incorporation or pursuant to the Delaware General Corporation Law. In 2016, we issued 39,501 shares of common stock upon exercise of stock options for total proceeds of $23,000 . In addition, we issued 40,429 shares of common stock to employees in connection with our employee stock purchase program for total proceeds of $139,000 . In 2017, we issued 156,927 shares of common stock upon exercise of stock options for total proceeds of $311,000 . In addition, we issued 43,561 shares of common stock to employees in connection with our employee stock purchase program for total proceeds of $201,000 . In 2018, we issued 231,407 shares of common stock upon exercise of stock options for total proceeds of $635,000 . In addition, we issued 46,850 shares of common stock to employees in connection with our employee stock purchase program for total proceeds of $352,000 . As of December 31, 2018 , we had 33,948,254 shares of common stock outstanding. Stock Offerings In January 2015, we filed a shelf registration statement on Form S-3 to offer and sell, from time to time, equity and debt securities in one or more offerings up to a total dollar amount of $150.0 million . On December 19, 2016, we entered into an At Market Issuance Sales Agreement with FBR Capital Markets & Co., or FBR, pursuant to which we were able to issue and sell shares of our common stock having an aggregate offering price up to $30.0 million , through FBR as our sales agent. In conjunction with the sales agreement, FBR received compensation based on an aggregate of 3% of the gross proceeds on the sale price per share of our common stock. Any sales made pursuant to the sales agreement were deemed an “at-the-market” offering and were made pursuant to the shelf registration statement on Form S-3. For the year ended December 31, 2016, we did not sell any shares through FBR under the sales agreement. During the six months ended June 30, 2017, we completed the sale of 4,501,985 shares of common stock under the Sales Agreement. Net proceeds, after deducting approximately $906,000 in commissions and fees and approximately $132,000 in offering costs, were approximately $28,962,000 . On July 12, 2017, we completed an underwritten public offering of 3,000,000 shares of common stock at an offering price of $7.50 per share for total gross proceeds of $22,500,000 . On August 11, 2017, we completed the closing of the exercise of the underwriter's option to purchase an additional 314,000 shares of common stock at the public offering price of $7.50 per share, resulting in additional gross proceeds of $2,355,000 . After giving effect to the exercise of the over-allotment option, the total number of shares sold by us in the public offering increased to 3,314,000 shares and gross proceeds increased to $24,855,000 . Net proceeds, after deducting underwriting commission and offering costs, were approximately $23,198,000 . In January 2018, we filed a new shelf registration statement on Form S-3 to offer and sell, from time to time, equity and debt securities in one or more offerings up to a total dollar amount of $150.0 million due to the expiration of our January 2015 shelf registration. In May 2018, we entered into an At Market Issuance Sales Agreement, or the Sales Agreement, with B. Riley FBR, Inc., and Oppenheimer & Co. Inc. acting as our distribution agents, relating to the sale of up to $50,000,000 of our common stock from time to time. We terminated the Sales Agreement in June 2018 after having sold 188,100 shares, representing gross proceeds of approximately $1,903,000 . Net proceeds, after deducting commission, fees and offering costs, were approximately $1,758,000 . On June 20, 2018, we entered into an underwriting agreement with Cantor Fitzgerald & Co., as representative of the underwriters, and on June 22, 2018 we completed a public offering of 5,326,314 shares of common stock, which included the underwriters' option to purchase additional shares, at a public offering price of $9.50 per share for total gross proceeds of approximately $50,600,000 . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $47,422,000 . On January 18, 2019, we entered into an underwriting agreement with Barclays Capital Inc. and Stifel, Nicolaus & Company, Incorporated, as representatives of the underwriters, and on January 23, 2019, we completed a public offering of 4,847,250 shares of our common stock, which included the exercise in full by the underwriters of their option to purchase 632,250 additional shares of the Company’s common stock, at a public offering price of $9.50 per share for total gross proceeds of approximately $46,049,000 . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $43,118,000 .

Stock-Based Awards and Benefit

Stock-Based Awards and Benefit Plan	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Awards and Benefit Plan	Stock-Based Awards and Benefit Plan On November 4, 2012, our board of directors adopted the Kindred Biosciences, Inc. 2012 Equity Incentive Plan (the “2012 Plan"). The 2012 Plan provided for our board of directors to grant incentive stock options or non-qualified stock options for the purchase of common stock, to issue or sell shares of restricted common stock and to grant stock appreciation rights (“SARs”) to our employees, directors, consultants and advisers of the Company. Pursuant to the terms of the 2012 Plan, no options or SARs shall be granted under the 2012 Plan after 10 years from the date of adoption of the 2012 Plan. We reserved 4,000,000 shares of our common stock for issuance under the 2012 Plan. The 2012 Plan terminated in May 2016 and 3,041,999 stock option shares which had been granted prior to the plan’s expiration remaining outstanding as of December 31, 2018 . In May 2016, we adopted the 2016 Equity Incentive Plan (the “2016 Plan”), and reserved 3,000,000 shares of our common stock for issuance under the 2016 Plan. The 2016 Plan was the successor to our 2012 Plan and all awards made under the 2012 Plan remained subject to the terms of that plan. Options granted under the 2016 Plan were either incentive stock options or nonstatutory stock options. The 2016 Plan also provided for the grant of stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards and other stock awards. The exercise price of a stock option was not less than 100% of the closing price of our common stock on the date of the grant. If, at any time we granted an option, and the optionee directly or by attribution owned stock possessing more than 10% of the total combined voting power of all classes of our stock, the option price was at least 110% of the fair value and was not exercisable more than five years after the date of grant. Options generally vested over a period of one or four years from the date of grant. Options granted under the 2016 Plan expired no later than 10 years from the date of grant. As of December 31, 2018 , there were 2,376,436 option shares outstanding, 187,500 restricted stock awards issued but unvested, and 315,000 restricted stock units granted but unvested, and no shares are available for future grants under the 2016 Plan since it was retired in June 2018. In June 2018, we adopted the 2018 Equity Incentive Plan (the “2018 Plan”), and reserved 3,000,000 shares of our common stock for issuance under the 2018 Plan. The 2018 Plan is the successor to our 2016 Plan. All awards made under the 2016 and 2012 Plans shall remain subject to the terms of these plans. Options granted under the 2018 Plan may be either incentive stock options or nonstatutory stock options. The 2018 Plan also provides for the grant of stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards and other stock awards. The exercise price of a stock option may not be less than 100% of the closing price of our common stock on the date of the grant. If, at any time we grant an incentive stock option, and the optionee directly or by attribution owns stock possessing more than 10% of the total combined voting power of all classes of our stock, the option price shall be at least 110% of the fair value and shall not be exercisable more than five years after the date of grant. Options generally vest over a period of one or four years from the date of grant. Options granted under the 2018 Plan expire no later than 10 years from the date of grant. As of December 31, 2018 , there were 403,493 option shares outstanding, and 2,596,507 shares available for future grants under the 2018 Plan. 2014 Employee Stock Purchase Plan In December 2014, our board of directors adopted the Kindred Biosciences, Inc. 2014 Employee Stock Purchase Plan (the “Purchase Plan”). A total of 200,000 shares of our common stock are authorized for issuance under the Purchase Plan. At the Annual Meeting of Stockholders of Kindred Biosciences, Inc. held on June 22, 2018, our stockholders approved an amendment to increase the number of shares that may be issued under the ESPP from 200,000 shares to 500,000 shares. The Purchase Plan permits eligible employees to purchase common stock at a discount through payroll deductions during defined six months consecutive offering periods beginning on December 1st. The price at which the stock is purchased is equal to the lower of 85% of the fair market value of the common stock on the first day of the offering or 85% of the fair market value of our common stock on the purchase date. A participant may purchase a maximum of 2,000 shares of common stock during each offering period, not to exceed $25,000 worth of common stock on the offering date during each calendar year. We use the Black-Scholes option pricing model, in combination with discounted employee price, in determining the value of the Purchase Plan expense to be recognized during each offering period. The weighted-average grant date fair value per share using the Black-Scholes option pricing model was $2.72 during the year ended December 31, 2018 . As of December 31, 2018 , there were 184,392 shares of common stock issued under the Purchase Plan and 315,608 shares available for future issuance under the Purchase Plan. At December 31, 2018 and 2017, we had an outstanding liability of $47,000 and $27,000 , respectively, which is included in accrued compensation on the consolidated balance sheets, for employee contributions to the Purchase Plan for shares pending issuance at the end of the next offering period. Reserved Shares At December 31, 2018 , shares of common stock reserved for future issuance inclusive of outstanding option shares are as follows: 2018 Equity Incentive Plan 2,596,507 2014 Employee Stock Purchase Plan 315,608 2,912,115 Stock Option Plan Activity Summary A summary of activity under our stock option plans is as follows: Shares Available For Grant Shares Issuable Under Options Weighted Average Exercise Price Weighted Average Remaining ContractualTerm (In Years) Aggregate Intrinsic Value Balance, December 31, 2015 726,402 3,116,185 $7.26 8.2 $2,908,000 2012 Plan terminated (a) (307,107 ) 2016 Plan authorized (b) 3,000,000 Granted (847,683 ) 847,683 $3.48 Exercised (39,501 ) $0.57 Expired 43,818 (43,818 ) $14.52 Forfeited - stock options 312,220 (312,220 ) $7.06 Balance, December 31, 2016 2,927,650 3,568,329 $6.36 7.5 $4,353,000 2012 Plan true up retired shares (c) (26,977 ) 2016 Plan issued RSA shares (d) (250,000 ) Granted (1,208,200 ) 1,208,200 $6.62 Exercised (156,927 ) $1.98 Expired 7,267 (7,267 ) $14.54 Forfeited - stock options 38,710 (38,710 ) $6.60 Balance, December 31, 2017 1,488,450 4,573,625 $6.57 7.2 $18,745,000 2012 Plan true up retired shares (e) (56,953 ) 2016 Plan RSA forfeited on 1/23/18 (f) 26,980 2016 Plan RSU issued on 1/22/18 (g) (315,000 ) 2016 Plan true up retired shares (h) (56,636 ) 2018 Incentive Plan (i) 3,000,000 Granted (1,607,193 ) 1,607,193 $9.78 Exercised (242,031 ) $3.19 Expired 36,791 (36,791 ) $13.05 Forfeited - stock options 80,068 (80,068 ) $7.40 Balance, December 31, 2018 2,596,507 5,821,928 $7.54 7.1 $ 24,780,000 Options vested and expected to vest, December 31, 2018 5,821,928 $7.54 7.1 $ 24,780,000 Options exercisable, December 31, 2018 3,716,187 $7.01 6.1 $ 18,806,000 (a) The 2012 Equity Incentive Plan terminated in May 2016. All shares available for grant under this Plan expired. (b) The 2016 Equity Incentive Plan was adopted and approved by stockholders in May 2016. (c) True up all expired shares available for grant under the 2012 Equity Incentive Plan, which was terminated in May 2016. (d) Issued 250,000 RSA shares on January 23, 2017 under the 2016 Equity Incentive Plan. (e) True up expired shares available for grant under the 2012 Equity Incentive Plan, which was terminated in May 2016. (f) Vested 62,500 RSA shares on January 23, 2018. 26,980 shares were forfeited to cover tax liability. (g) Issued 315,000 RSU units on January 22, 2018 under the 2016 Equity Incentive Plan. (h) The 2016 Equity Incentive Plan terminated in June 2018. All shares available for grant under this Plan expired. (i) The 2018 Equity Incentive Plan was adopted and approved by stockholders in June 2018. The aggregate intrinsic value of options is calculated as the difference between the exercise price of options and the fair value of our common stock for those options that had exercise prices lower than the fair value of our common stock on December 31, 2018 , 2017 and 2016. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2018 , 2017 and 2016 was $2,261,000 , $911,000 and $117,000 , respectively. We received proceeds of $635,000 , $311,000 and $23,000 from the exercise of common stock options during the years ended December 31, 2018 , 2017 and 2016, respectively. The weighted-average grant date fair value of options granted during the years ended December 31, 2018 , 2017 and 2016 was $5.58 , $4.21 and $2.45 per share, respectively. Restricted Stock On January 23, 2017, we granted 250,000 shares of restricted stock awards to four employees. Shares will vest 25% on each one year anniversary of the grant date provided that the employee is in the employment of the Company on such vesting date. The total stock-based compensation expense related to these awards is $1,600,000 . On January 22, 2018, we granted 315,000 shares of restricted stock units to four employees. Shares will vest 25% on each one year anniversary of the grant date provided that the employee is in the employment of the Company on such vesting date. The total stock-based compensation expense related to these units is $2,756,000 . As of December 31, 2018 , we have an aggregate of approximately $2,933,000 unrecognized stock-based compensation expense for restricted stock awards outstanding which is expected to be recognized over a weighted-average period of 2.8 years. Restricted stock activity for the year ended December 31, 2018 , was as follows: Restricted Stock Award Shares Weighted Average Grant Date Fair Value Unvested balance at December 31, 2017 250,000 $6.40 Granted — — Vested (62,500 ) 6.40 Forfeited — — Unvested balance at December 31, 2018 187,500 $6.40 Restricted Stock Units Shares Weighted Average Grant Date Fair Value Unvested balance at December 31, 2017 — — Granted 315,000 $8.75 Vested — — Forfeited — — Unvested balance at December 31, 2018 315,000 $8.75 Stock-Based Compensation We recognize stock-based compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, we have considered our historical experience to estimate pre-vesting forfeitures for service-based awards. The impact of a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual forfeiture rate is materially different from our estimate, we may be required to record adjustments to stock-based compensation expense in future periods. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. Due to insufficient company-specific historical and implied volatility information, we used to estimate the expected stock price volatility based on the historical volatility of publicly traded peer companies. During the quarter ended March 31, 2018, an analysis was completed to compare our own stock volatility to the volatility calculated using peer analysis. The conclusion was that Kindred Biosciences has enough history to provide a reliable expected volatility. As a result, we use the volatility of our own stock. The expected term of our common stock options has been determined utilizing the “simplified” method as we have insufficient historical experience for options grants overall, rendering existing historical experience irrelevant to expectations for current grants. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that we have never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. Total stock-based compensation expense, related to all of our share-based payment awards, is comprised of the following: (In thousands) Years Ended December 31, 2018 2017 2016 Research and development $1,746 $1,650 $1,463 General and administrative 4,531 3,557 2,164 $6,277 $5,207 $3,627 Total stock-based compensation expense includes stock options, restricted stock awards, restricted stock units, and expense from the Purchase Plan for the years ended December 31, 2018 , 2017, and 2016. We had an aggregate of approximately $9,093,000 of unrecognized stock-based compensation expense for unvested stock-based awards as of December 31, 2018 , which is expected to be recognized over a weighted average period of 2.8 years . Valuation assumptions The relevant data used to determine the fair value of stock-based awards is as follows: Years Ended December 31, 2018 2017 2016 Stock options: Weighted average risk-free interest rate 2.62% 1.98% 1.61% Weighted average expected term (in years) 5.9 6.0 6.3 Weighted average expected volatility 59.2% 70.4% 83.4% Weighted average expected dividend yield — — — Fair value at grant date $5.58 $4.21 $2.45 Employee stock purchase plan: Weighted average risk-free interest rate 2.02% 1.04% 0.50% Weighted average expected term (in years) 0.5 0.5 0.5 Weighted average expected volatility 43.7% 56.7% 84.4% Weighted average expected dividend yield — — — Fair value at grant date $2.72 $1.73 $1.42 Restricted stock awards: Fair value at grant date — $6.40 — Restricted stock units: Fair value at grant date $8.75 — —

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases In April 2014, we entered into non-cancelable operating leases for 2,145 square feet of laboratory space through May 2017 and 6,900 square feet of office space through November 2017. In January, August and November 2015, we amended our original operating lease for laboratory space to expand the facility with an additional 2,431 square feet, 131 square feet and 123 square feet, respectively, of manufacturing space through May 2017. In February and October 2016, we further amended our original operating lease for laboratory space to further expand the facility with an additional 3,599 square feet and 2,326 square feet, respectively, of quality control and laboratory space through May 2017. In February 2017, we further amended our existing lease for an expansion of an additional 721 square feet of laboratory space. Commencing on June 1, 2017, the non-cancellable operating lease for the entire existing laboratory space of a total 11,476 square feet is extended for another five years through May 2022. In August 2015, we entered into a new non-cancelable operating lease for 3,126 square feet of office space in San Diego, California through September 2019. In April 2017, we renewed our headquarters office lease for 6,900 square feet of office space in Burlingame, California through November 30, 2020 and in June 2017, we amended the lease with an additional 1,190 square feet of office space through November 30, 2020. In October 2018, we entered into a sublease agreement for an additional 5,613 square feet of laboratory space next to our current laboratory facility. The sublease agreement expires on March 31, 2019. After that, the lease will continue on a month-to-month basis unless or until terminated by either party, with or without cause, by giving the other party 30 days written notice, provided that the extended term shall not extend beyond December 31, 2019. Rent expense for the years ended December 31, 2018 , 2017 and 2016 was $814,000 , $679,000 and $522,000 , respectively. As of December 31, 2018 , we are obligated to make minimum lease payments under all of our operating leases as follows (in thousands): Year ending December 31, Lease Payments 2019 $ 835 2020 726 2021 459 2022 194 Thereafter — Total $ 2,214 In March 2018, we entered into a standard form of agreement with CRB Builders, LLC (“CRB”) in connection with the renovation of the Plant. Pursuant to the agreement, CRB will provide pre-construction and construction services in connection with constructing and renovating the Plant to provide approximately 16,500 square feet of new production space and supporting Fill and Finish and Bio Production processes (the “Project”). The date for substantial completion of CRB’s work on the Project is anticipated to be in mid-2019, which is subject to adjustment in accordance with the terms of the agreement as the renovation progresses, or as agreed and requested by us. The agreement is subject to customary undertakings, covenants, obligations, rights and conditions. Purchase Commitments In June 2018, we entered into a Strategic Supply Agreement (the “Agreement”), with Pall Corporation (“Pall”) for purchase of equipment and consumables to be used in support of our manufacturing requirements, including, but not limited to, the Plant. Pursuant to the Agreement, we will purchase certain pharmaceutical manufacturing equipment and related services in the aggregate amount of $3.8 million with a seven -year consumable purchase obligation in the aggregate amount of approximately $16.5 million . The Agreement is subject to customary undertakings, covenants, obligations, rights and conditions. We have incurred $3,286,000 in equipment purchase costs and $588,000 in other purchase costs as of December 31, 2018 . Indemnities and Guarantees We have made certain indemnities and guarantees, under which we may be required to make payments to a guaranteed or indemnified party, in relation to certain transactions. We indemnify our officers and directors to the maximum extent permitted under the laws of the State of Delaware. The duration of these indemnities and guarantees varies and, in certain cases, is indefinite. These indemnities and guarantees do not provide for any limitation of the maximum potential future payments we could be obligated to make. Historically, we have not been obligated to make any payments for these obligations and no liabilities have been recorded for these indemnities and guarantees in the accompanying consolidated balance sheets. Legal Matters In the ordinary course of business, we may face various claims brought by third parties and may, from time to time, make claims or take legal actions to assert our rights, including intellectual property disputes, contractual disputes and other commercial disputes. Any of these claims could subject us to litigation. Management believes there are currently no claims that are likely to have a material effect on our consolidated financial position and results of operations.

Restructuring Plan

Restructuring Plan	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring Plan	Restructuring Plan On January 8, 2016, our Board of Directors committed to a restructuring plan intended to better align our workforce to our revised operating needs and program development plans. On January 11, 2016, we implemented the restructuring plan that focused on streamlining our development programs and to ensure our remaining funds are sufficient to fund our planned operations through 2018. To match these priorities, we reduced our workforce by 18 positions, or approximately 31% of our workforce, resulting in a total workforce of 39 positions. As a result of the restructuring plan which has been completed, we recorded a restructuring charge of approximately $655,000 related to severance payments which was entirely paid in the quarter ended March 31, 2016. There were no further restructuring charges since then.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes There is no provision for income taxes because we have historically incurred operating losses and we maintain a full valuation allowance against our net deferred tax assets. Differences between the provision (benefit) for income taxes and income taxes at the statutory federal income tax rate are as follows: (In thousands, except percentages) For the years ended December 31, 2018 2017 2016 Income tax expense (benefit) at statutory federal rate $ (10,436 ) 21.0 % $ (10,499 ) 34.0 % $ (7,651 ) 34.0 % State income tax, net of federal benefit (3,748 ) 7.5 (1,880 ) 6.1 (1,389 ) 6.2 Permanent items 13 — 63 (0.2 ) 38 (0.2 ) Research credits (1,909 ) 3.8 (1,172 ) 3.8 (970 ) 4.3 Stock-based compensation (237 ) 0.5 (122 ) 0.4 (29 ) 0.1 ASC 740-10 864 (1.7 ) 469 (1.5 ) 388 (1.7 ) Change in valuation allowance 14,949 (30.1 ) (128 ) 0.4 9,602 (42.6 ) Tax Cuts and Jobs Act — — 13,092 (42.4 ) — — Other 504 (1.0 ) 177 (0.6 ) 11 (0.1 ) Provision (benefit) for income taxes $ — — % $ — — % $ — — % Deferred tax assets are recognized for temporary differences that will result in deductible amounts in future periods. The components of the deferred tax assets are as follows at December 31, 2018 and 2017 : December 31, (In thousands) 2018 2017 Deferred tax assets: Net operating loss carryforwards $ 39,579 $ 26,369 Research & development credits 3,589 3,044 Accrued expenses 893 753 Amortization and depreciation (393 ) (132 ) Stock-based compensation 6,173 4,860 Other 10 12 49,851 34,906 Valuation Allowance (49,851 ) (34,906 ) Net current deferred tax assets $ — $ — At December 31, 2018 , we had net deferred tax assets of $49,851,000 . Due to uncertainties surrounding our ability to generate future taxable income to realize these assets, a full valuation allowance has been established to offset the net deferred tax asset. Additionally, the future utilization of our net operating loss and research and development tax credits carryforwards is subject to annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, and similar state tax provisions due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes limit the amount of the net operating loss and research and development tax credit carryforward and other deferred tax assets that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Sections 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percent points over a three -year period. We believe we incurred ownership changes since April 2014, however, we have not completed an analysis yet to determine the impact of our ability to use net operating losses and research and development credits as of December 31, 2018 . At December 31, 2018 , we had federal and California net operating loss carryovers of $139,843,000 and $139,763,000 , respectively. The federal and California net loss carryforwards will begin to expire in 2032. At December 31, 2018 , we had federal and state research tax credit carryovers of approximately $3,625,000 and $3,617,000 , respectively. The federal research and development tax credit carryforwards will begin to expire in 2033. The California research and development credit carryforwards are available indefinitely. The impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more likely than not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. There were no unrecognized tax benefits recorded by us as of the date of adoption. As a result of the implementation, we did not recognize an increase in the liability for unrecognized tax benefits. A rollforward of changes in our unrecognized tax benefits is shown below. (In thousands) December 31, 2018 2017 2016 Balance at beginning of year $ 2,252 $ 1,698 $ 1,234 Additions based on tax positions related to the current year 944 554 464 Additions for tax positions of prior years — — — Balance at end of year $ 3,196 $ 2,252 $ 1,698 The amount of unrecognized tax benefits that would impact the effective tax rate if recognized and realized is $2,893,000 . Our practice is to recognize interest and/or penalties related to income tax matters as income tax expense. We had no accrual for interest or penalties on our accompanying consolidated balance sheets at December 31, 2018 , 2017 and 2016, and have not recognized interest and/or penalties in our consolidated statements of operations and comprehensive loss for the years ended December 31, 2018 , 2017 and 2016. We do not anticipate a significant change to our unrecognized tax benefits during the next twelve months . We file tax returns as prescribed by tax laws of the jurisdictions in which we operate. In the normal course of business, we are subject to examination by federal and state jurisdictions, where applicable. There are currently no pending tax examinations. Our federal and state tax returns are still open under statute from 2013 to present. On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (the "Act"). The Act amended the Internal Revenue Code to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. For businesses, the Act reduced the corporate tax rate from a maximum of 35% to a flat 21% rate. The rate reduction was effective on January 1, 2018. As a result of the rate reduction, we have reduced the deferred tax asset balance as of December 31, 2017 by $13.1 million . Due to our full valuation allowance position, we have also reduced the valuation allowance by the same amount. We have completed our evaluation of the potential impacts of IRC Section 162(m) as amended by the Act of 2017 and concluded there is no impact on our December 31, 2018 financial statements.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic and diluted net loss per share was calculated as follows for the years ended December 31, 2018 , 2017 and 2016: (In thousands, except per share amounts) Years Ended December 31, 2018 2017 2016 Basic and diluted net loss per share attributable to common stockholders: Numerator: Net loss attributable to common stockholders $ (49,690 ) $ (30,879 ) $ (22,499 ) Denominator: Weighted-average number of common shares outstanding, basic and diluted 31,001 25,084 19,873 Net loss per common share attributable to common stockholders, basic and diluted $ (1.60 ) $ (1.23 ) $ (1.13 ) There was no difference between our net loss and the net loss attributable to common stockholders for all periods presented. Stock options to purchase 5,821,928 shares, 4,573,625 shares and 3,568,329 shares of common stock as of December 31, 2018 , 2017 and 2016 , respectively, were excluded from the computation of diluted net loss per share attributable to common stockholders because their effect was anti-dilutive. 187,500 shares unvested restricted stock award as of December 31, 2018 and 250,000 shares unvested restricted stock award as of December 31, 2017 were also excluded from the computation of diluted net loss per share calculations because their effect was anti-dilutive. 315,000 units of granted but unvested restricted stock units as of December 31, 2018 were also excluded from the computation of diluted net loss per share calculations because their effect was anti-dilutive.

Employee Savings Plan

Employee Savings Plan	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Savings Plan	Employee Savings Plan We have established an employee savings plan pursuant to Section 401(k) of the Internal Revenue Code, effective May 1, 2014. The plan allows participating employees to deposit into tax deferred investment accounts up to 90% of their salary, subject to annual limits. We make contributions to the plan in an amount equal to 50% on the first 6% for a maximum of 3% of the participant’s compensation which is deferred. We contributed approximately $292,000 , $149,000 and $101,000 to the plan during the years ended December 31, 2018 , 2017 and 2016, respectively.

Selected Quarterly Financial In

Selected Quarterly Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (unaudited)	Selected Quarterly Financial Information (unaudited) The following table presents selected unaudited quarterly financial data for each of the quarters in the years ended December 31, 2018 and 2017 . (In thousands, except per share amounts) 2018 2017 Quarter ended Dec. 31 Sep. 30 Jun. 30 Mar. 31 Dec. 31 Sep. 30 Jun. 30 Mar. 31 Net product revenues $ 1,326 $ 640 $ — $ — $ — $ — $ — $ — Operating costs and expenses Cost of product revenues 214 110 — — — — — — Research and development 7,756 7,477 5,820 5,346 5,142 4,877 3,866 3,780 General and administrative 9,219 6,608 5,770 4,902 4,820 3,269 3,056 2,843 Total operating cost and expenses 17,189 14,195 11,590 10,248 9,962 8,146 6,922 6,623 Loss from operations (15,863 ) (13,555 ) (11,590 ) (10,248 ) (9,962 ) (8,146 ) (6,922 ) (6,623 ) Interest and other income, net 422 518 349 277 232 256 155 131 Net loss $ (15,441 ) $ (13,037 ) $ (11,241 ) $ (9,971 ) $ (9,730 ) $ (7,890 ) $ (6,767 ) $ (6,492 ) Net loss per share, basic and diluted (1) $ (0.46 ) $ (0.39 ) $ (0.39 ) $ (0.36 ) $ (0.35 ) $ (0.29 ) $ (0.29 ) $ (0.30 ) Weighted average shares used in computing net loss per share, basic and diluted 33,708 33,601 28,619 27,986 27,915 27,400 23,409 21,516 (1) Net loss per share for each quarter is calculated as a discrete period; the sum of four quarters may not equal the calculated full year amount.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 18, 2019, we entered into an underwriting agreement (the “Underwriting Agreement”) with Barclays Capital Inc. and Stifel, Nicolaus & Company, Incorporated, as representatives of the underwriters, and on January 23, 2019, we completed a public offering of 4,847,250 shares of common stock, which includes the exercise in full by the underwriters of their option to purchase 632,250 additional shares of our common stock, at a public offering price of $9.50 per share for total gross proceeds of approximately $46 million . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $43.1 million . On February 1, 2019, we filed a Certificate of Incorporation with the State of Delaware for a wholly owned subsidiary, Centaur Biopharmaceutical Services, Inc. (the "Subsidiary"). The Subsidiary has one class of capital stock which is designated common stock, $0.0001 par value per share. The authorized number of shares of common stock for the Subsidiary is 1,000 .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Liquidity	Liquidity We have incurred losses and negative cash flows from operations and had an accumulated deficit of $161.7 million as of December 31, 2018 . We expect to continue to incur losses and negative cash flows, which will increase significantly from historical levels as we expand our product development activities, seek regulatory approvals for our product candidates, establish a biologics manufacturing capability, and commercialize approved products. We might require additional capital until such time as we can generate operating revenues in excess of operating expenses. To date, we have been funded primarily through sales of convertible preferred stock and the sale of our common stock in our initial public offering in December 2013, in which we raised approximately $67.0 million , net of offering costs. In April 2014, we completed a follow-on public offering of common stock, resulting in net proceeds of approximately $58.1 million . In 2017, we completed the sale of common stock under an At Market Issuance Sales Agreement, or the Sales Agreement as well as an underwritten public offering, resulting in net proceeds of approximately $29.0 million and $23.2 million , respectively. In May 2018, we entered into another Sales Agreement, but terminated the Sales Agreement in June 2018 after having sold 188,100 shares, representing gross proceeds of approximately $1.9 million . Net proceeds, after deducting commission, fees and offering costs, were approximately $1.8 million . Also, in June 2018 we completed a public offering of 5,326,314 shares of common stock, which included the underwriters' option to purchase additional shares, at a public offering price of $9.50 per share for total gross proceeds of approximately $50.6 million . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $47.4 million . In January 2019, we completed a public offering of 4,847,250 shares of common stock, which includes the exercise in full by the underwriters' option to purchase 632,250 additional shares of the Company’s common stock, at a public offering price of $9.50 per share for total gross proceeds of approximately $46.0 million . Net proceeds, after deducting underwriting discounts and commissions and offering expenses were approximately $43.1 million . As of December 31, 2018, we believe our cash, cash equivalents and investments in available-for-sale securities of approximately $73.9 million and together with the $43.1 million raised in January 2019, are sufficient to fund our planned operations for at least the next 24 months. If we require additional funding for operations, we may seek such funding through public or private equity or debt financings or other sources, such as corporate collaborations and licensing arrangements. We may not be able to obtain financing on acceptable terms, or at all, and we may not be able to enter into corporate collaborations or licensing arrangements. The terms of any financing may result in dilution or otherwise adversely affect the holdings or the rights of our stockholders. If we are unable to obtain funding, we could be forced to delay, reduce or eliminate our research and development programs or commercialization efforts, which could adversely affect our business prospects.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of the Company and its wholly owned Subsidiary. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting periods. Estimates are based historical experiences or on forecasts, including information received from third parties and other assumptions that the Company believes are reasonable under the circumstances. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from those estimates.
Cash, Cash Equivalents and Investments	Cash, Cash Equivalents and Investments We consider all highly liquid investments purchased with an original maturity of three months or less at the date of acquisition to be cash equivalents. Debt securities with original maturities greater than three months and remaining maturities less than one year are classified as short-term investments. We classify all investments as available-for-sale. Available-for-sale securities are carried at estimated fair value, with accumulated unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in the accompanying consolidated balance sheets. Realized gains or losses on the sale of investments are determined on a specific identification method, and such gains and losses are reflected as a component of interest and other income, net in the accompanying consolidated statements of operations and comprehensive loss. Marketable securities investments are evaluated periodically for impairment. We take into account general market conditions, changes in the economic environment as well as specific investment attributes, such as credit downgrade or illiquidity for each investment, the expected cash flows from the securities, our intent to sell the securities and whether or not we will be required to sell the securities before the recovery of their amortized cost, to estimate the fair value of our investments and to determine whether impairment is other than temporary. If it is determined that a decline in fair value of any investment is other than temporary, then the unrealized loss related to credit risk would be included in interest and other income, net.
Concentration of Credit Risk and of Significant Suppliers and Customers	Concentration of Credit Risk and of Significant Suppliers and Customers Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents and investments. From time to time, we maintain cash and cash equivalent balances in excess of amounts insured by the Federal Deposit Insurance Corporation (“FDIC”) and the Securities Investor Protection Corporation ("SIPC"). Primarily all of our cash, cash equivalents and investments at December 31, 2018 were in excess of amounts insured by the FDIC and SIPC. We do not believe that we are subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. We are dependent on third-party manufacturers to supply products for research and development activities in our programs. In particular, we rely on a small number of manufacturers to supply us with our requirements for the active pharmaceutical ingredients, or API, and formulated drugs related to some of these programs. These programs would be adversely affected by a significant interruption in the supply of API. We are also dependent on a combination of national and regional distributors for our product sales of Mirataz. See Note 3.
Fair Value Measurements	Fair Value Measurements We use the provisions of Accounting Standards Codification ("ASC") 820, “ Fair Value Measurements and Disclosure", to determine the fair values of our financial and nonfinancial assets and liabilities where applicable. ASC 820 defines fair value, establishes a framework for measuring fair value in U.S. GAAP and expands disclosure about fair value measurements. The objective of fair value measurement is to determine the price that would be received to sell the asset or paid to transfer the liability (an exit price) in an orderly transaction between market participants at the measurement date. ASC 820 emphasizes that fair value is a market-based measurement, not an entity-specific measurement, and that market participant assumptions include assumptions about risk and effect of a restriction on the sale or use of an asset. To increase consistency and comparability in fair value measurement and related disclosures, ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels: (1) Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date; (2) Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly through corroboration with observable market data; and (3) Level 3 inputs are unobservable inputs for the asset or liability that reflect the reporting entity’s own assumptions about risk and the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. Government agency notes, corporate notes and commercial papers are recorded at their estimated fair value. Since these available-for-sale securities generally have market prices from multiple sources and it can be difficult to select the best individual price directly from the quoted prices in the active markets, we use Level 2 inputs for the valuation of these securities. Using the Level 2 inputs, a “consensus price” or a weighted average price for each of these securities can be derived from a distribution-curve-based algorithm which includes market prices obtained from a variety of industrial standard data providers (e.g. Bloomberg), security master files from large financial institutions, and other third-party sources. The carrying amount of financial instruments, including cash, accounts payable and accrued liabilities approximate fair value due to the short maturities of these financial instruments. Financial assets, which consist of money market funds and available-for-sale securities, are measured at fair value on a recurring basis (see Note 4). We measure certain financial assets at fair value on a recurring basis, including cash equivalents and available-for-sale securities. The fair value of these financial assets was determined based on a three-tier fair value hierarchy as described in Note 2, which prioritizes the inputs used in measuring fair value.
Property and Equipment	Property and equipment are stated at cost less accumulated depreciation and amortization. We calculate depreciation using the straight-line method over the estimated useful lives of the assets, which range from two to five years for furniture, fixtures, lab and computer equipment and software, and fifteen to thirty-nine years for land improvements and real property. Land and assets held within construction in progress are not depreciated. Construction in progress is related to the construction or development of property and equipment that have not yet been placed in service for their intended use. Expenditures for repairs and maintenance of assets are charged to expense as incurred. We amortize leasehold improvements using the straight-line method over the estimated useful lives of the respective assets or the lease term, whichever is shorter. Upon retirement or sale, the cost and related accumulated depreciation and amortization of assets disposed of are removed from the accounts and any resulting gain or loss is included in other income/expense.
Licenses	Licenses The costs incurred for the rights to use licensed technologies in the research and development process, including licensing fees and milestone payments, are charged to research and development expense as incurred in situations where we have not identified an alternative future use for the acquired rights, and are capitalized in situations where we have identified an alternative future use. No costs associated with the use of licensed technologies have been capitalized to date.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We review long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that we consider in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, we compare forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows.
Revenue Recognition	Revenue Recognition We adopted ASC Topic 606 (“ASC 606”), "Revenue from Contracts with Customers" in the first quarter of our fiscal year that began on January 1, 2018. This new standard replaced the previous revenue recognition guidance in U.S. GAAP. No prior period adjustments were needed as our first commercial shipments began in July 2018. Our revenue consists of product revenue resulting from the sale of Mirataz for the management of weight loss in cats. We account for a contract with a customer when there is a legally enforceable contract between us and our customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. Our customers could either be distributors who subsequently resell our products to third parties such as veterinarians, clinics or animal hospitals or the third parties themselves. We use a contract manufacturer to produce Mirataz and a third-party logistics vendor to process and fulfill orders. We concluded we are the principal in our sales because we control access to services rendered by both vendors and direct their activities. We have no significant obligations to distributors to generate pull-through sales. In accordance with ASC 606, we applied the following steps to recognize revenue for the sale of Mirataz that reflects the consideration to which we expect to be entitled to receive in exchange for the promised goods: 1. Identify the contract with a customer A contract with a customer exists when we enter into an enforceable contract with a customer. These contracts define each party's rights, payment terms and other contractual terms and conditions of the sale. We apply judgment in determining the customer’s ability and intention to pay, which is based on published credit and financial information pertaining to the customer. 2. Identify the performance obligations in the contract Our product in a given purchase order is delivered at the same time and we do not separate an individual order into separate performance obligations. We have concluded the sale of finished goods and related shipping and handling are accounted for as a single performance obligation as there are no other promises to deliver goods beyond what is specified in each accepted customer order. 3. Determine the transaction price The transaction price is determined based on the consideration to which we will be entitled to receive in exchange for transferring goods to the customer, typically a fixed consideration in our contractual agreements. 4. Allocate the transaction price to the performance obligations The transaction price is allocated entirely to the performance obligation to provide pharmaceutical products. The nature of the promises/obligations under our contracts is to transfer a distinct good. Accordingly, because a single performance obligation exists, no allocation of the transaction price is necessary. 5. Determine the satisfaction of performance obligation Revenue is recognized when control of the finished goods is transferred to the customer, net of applicable reserves for variable consideration. Control of the finished goods is transferred at a point in time, upon delivery to the customer. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price, which includes estimates of variable consideration for which reserves are established. Components of variable consideration include product returns, allowances and discounts. These estimates take into consideration a range of possible outcomes for the expected value (probability-weighted estimate) or relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the respective underlying contracts. The amount of variable consideration included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized where the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect net product revenues and earnings in the period such variances become known. Product Returns Consistent with the industry practice, we generally offer customers a limited right of return of damaged or expired product that has been purchased directly from us. Our return policy generally allows customers to receive credit for expired products within 90 days after the product’s expiration date. We estimate the amount of our product revenues that may be returned by our customers and record these estimates as a reduction of product revenues in the period the related product revenues are recognized, as well as within accrued liabilities, in the consolidated balance sheets. We currently estimate product return liabilities using probability-weighted available industry data and data provided by the our distributors such as the inventories remaining in the distribution channel. To-date, we have no returns and believe that returns of our product in future periods will be minimal. We do not record a return asset associated with the returned damaged or expired goods due to such asset is deemed to be fully impaired at the time of product return. Sales Discounts and Allowances We compensate our distributors for sales order management, data and distribution and other services through sales discounts and allowances. However, such services are not distinct from our sale of products to distributors and, therefore, these discounts and allowances are recorded as a reduction of product revenues in the statements of operations, as well as a reduction to accounts receivable in the consolidated balance sheets. Practical Expedients and Exemptions We generally expense sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses. Cost of Product Revenues Cost of product revenues consists primarily of the cost of direct materials, direct labor and overhead costs associated with manufacturing, inbound shipping and other third-party logistics costs. Inventories We value inventory at the lower of cost or net realizable value. We determine the cost of inventory using the standard-cost method, which approximates actual cost based on a first-in, first-out method. We analyze our inventory levels quarterly and write down inventory subject to expire in excess of expected requirements, or that has a cost basis in excess of its expected net realizable value. These inventory related costs are recognized as cost of product revenues on the accompanying Consolidated Statements of Operations and Comprehensive Loss. Currently our inventory consists of finished goods only.
Research and Development Costs	Research and Development Costs All costs of research and development are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, stock-based compensation expense, fees paid to consultants, outside service providers, professional services, travel costs and materials used in clinical trials and research and development.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing patent applications are recorded in research and development expenses when incurred, as recoverability of such expenditures is uncertain.
Stock-Based Compensation	Stock-Based Compensation Our stock-based compensation plan (see Note 9) provides for the grant of stock options, restricted common stock, restricted stock units and stock appreciation rights. The estimated fair values of employee stock option grants are determined as of the date of grant using the Black-Scholes option pricing model. This method incorporates the fair value of our common stock at the date of each grant and various assumptions such as the risk-free interest rate, expected volatility based on historic volatility of Kindred Biosciences own stock prices, and expected dividend yield, and expected term of the options. The estimated fair values of restricted stock awards are determined based on the fair value of our common stock on the date of grant. The estimated fair values of stock-based awards, including the effect of estimated forfeitures, are expensed over the requisite service period, which is generally the awards’ vesting period. We classify stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified. Our accounting policy for equity instruments issued to consultants and vendors in exchange for goods and services follows Financial Accounting Standards Board ("FASB") guidance. All transactions in which goods or services are the consideration received for the issuance of equity instruments are accounted for based on the fair value of the consideration received or the fair value of the equity instrument issued, whichever is more reliably measurable. The measurement date of the fair value of the equity instrument issued is the earlier of the date on which the counterparty’s performance is complete or the date at which a commitment for performance is reached. Non-employee grants of stock-based compensation, except those grants to non-employee, shareholder-approved Board Members, were previously valued under ASC 505-50 "Equity-Based Payments to Non-Employees". In Q2 2018, we adopted ASU 2018-07 "Compensation - Stock Compensation (Topic 718) - Improvements to Non-Employee Share-Based Payment Accounting" and non-employee grants are now valued in the same manner as employee grants.
Income Taxes	Income Taxes We account for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in our tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. We assess the likelihood that our deferred tax assets will be recovered from future taxable income and, to the extent we believe, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. We account for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.
Comprehensive Loss	Comprehensive Loss Our comprehensive loss includes the change in unrealized gains or losses on available-for-sale securities. The cumulative amount of gains or losses is reflected as a separate component of stockholders' equity in the accompanying consolidated balance sheets as accumulated other comprehensive loss.
Segment Data	Segment Data We manage our operations as a single segment for the purposes of assessing performance and making operating decisions. We are a veterinary biotechnology company focusing on developing therapies for pets. Our chief operating decision maker is our Chief Executive Officer. All assets are held in the United States.
Basic and Diluted Net Loss Per Common Share	Basic and Diluted Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders for the period by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders for the period by the weighted average number of common shares, including potential dilutive shares of common stock assuming the dilutive effect of potentially dilutive securities. For periods in which we have reported a net loss, diluted net loss per common share is the same as basic net loss per common share, since the impact of the potentially dilutive securities would be anti-dilutive to the calculation of net loss per common share (see Note 13).
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, "Leases (Topic 842)", requiring organizations that lease assets—referred to as “lessees”—to recognize on the consolidated balance sheet the assets and liabilities for the rights and obligations created by those leases. Under the new guidance, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. The ASU on leases will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. In July 2018, the FASB issued ASU No. 2018-10, "Codification Improvements to Topic 842, Leases", which affects narrow aspects of the guidance issued in ASU No. 2016-02. The amendments in this ASU related to transition do not include amendments from proposed ASU, Leases (Topic 842): Targeted Improvements, specific to a new and optional transition method to adopt the new lease requirements in ASU 2016-02. For entities that have not adopted Topic 842, the effective date and transition requirements will be the same as the effective date and transition requirements in Topic 842. In July 2018, the FASB issued ASU No. 2018-11, "Targeted Improvements to Topic 842, Leases". This update provides another transition method in addition to the existing transition method by allowing entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. For entities that have not adopted Topic 842, the effective date and transition requirements will be the same as the effective date and transition requirements in Topic 842. We adopted ASC 842 as of January 1, 2019. In preparation of adopting ASC 842, we have purchased a special lease software and also implemented additional internal controls to enable future preparation of financial information in accordance with ASC 842. We believe the largest impact will be on the consolidated balance sheets for the accounting of facilities-related leases, which represent a majority of the operating leases the Company has entered into. These leases will be recognized under the new lease standard as ROU (Right of Use) assets and operating lease liabilities. We will also be required to provide expanded disclosures for the leasing arrangements. As of December 31, 2018 , we had $2.2 million of undiscounted future minimum operating lease commitments that are not recognized on our consolidated balance sheets under the new standard. We are still in the process of finalizing the evaluations of the effect of ASU 842 on our consolidated financial statements and disclosures and will finalize our accounting assessment and quantitative impact of the adoption in the first quarter of 2019. In July 2018, the FASB issued ASU No. 2018-09, "Codification Improvements", and the amendments in this ASU affect a wide variety of Topics in the Codification. It applies to all reporting entities within the scope of the affected accounting guidance. It will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We have adopted the new guidance and the impact of this standard does not have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, "Fair Value Measurement (Topic 820)", which changes to disclosure requirements for fair value measurement. The amendments of this update modify the disclosure requirements on fair value measurements about Topic 820. It applies to all reporting entities within the scope of the affected accounting guidance. It will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are currently evaluating the new guidance and have not determined the impact this standard may have on our consolidated financial statements. We do not believe there are any other recently issued standards not yet effective that will have a material impact on our consolidated financial statements when the standards become effective.

Revenue and Cost of Product R_2

Revenue and Cost of Product Revenues (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue and Cost of Product Revenues	The following table presents revenues and cost of product revenues for the year ended December 31, 2018 (there were no revenues recognized in previous years) (in thousands): Year Ended December 31, 2018 Gross product revenues $ 2,027 Less allowance for product returns (61 ) Net product revenues 1,966 Cost of product revenues (324 ) Gross Profit $ 1,642

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of financial assets measured at fair value on a recurring basis	The following table presents information about our financial assets that are measured at fair value on a recurring basis as of December 31, 2018 and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: (In thousands) Fair Value Measurements as of December 31, 2018 Description Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Cash equivalents: Money market funds $ 1,276 $ 1,276 $ — $ — U.S. treasury bills 500 500 — — Commercial paper 45,332 — 45,332 — U.S. treasury bonds and notes 7,949 — 7,949 — Short-term investments: Commercial paper 5,353 — 5,353 — Corporate notes 12,277 — 12,277 — $ 72,687 $ 1,776 $ 70,911 $ — The following table presents information about our financial assets that are measured at fair value on a recurring basis as of December 31, 2017 and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value: (In thousands) Fair Value Measurements as of December 31, 2017 Description Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Unobservable Inputs (Level 3) Cash equivalents: Money market funds $ 801 $ 801 $ — $ — Commercial paper 31,977 — 31,977 — Corporate notes 1,500 — 1,500 — Short-term investments: Commercial paper 22,052 — 22,052 — US government agency notes 6,746 — 6,746 — U.S. treasury bonds and notes 3,482 3,482 — — Corporate notes 13,927 — 13,927 — Long-term investments: Corporate notes 1,499 — 1,499 — $ 81,984 $ 4,283 $ 77,701 $ —

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of fair value of available-for-sale short term investments	The following tables summarize our investments in available-for-sale securities by significant investment category reported as short-term or long-term investments as of December 31, 2018 and 2017 (in thousands): December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: Commercial paper $ 5,353 $ — $ — $ 5,353 Corporate notes 12,288 — (11 ) 12,277 17,641 — (11 ) 17,630 Total available-for-sale investments $ 17,641 $ — $ (11 ) $ 17,630 December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term investments: Commercial paper $ 22,052 $ — $ — $ 22,052 U.S. government agency notes 6,750 — (4 ) 6,746 U.S. treasury bonds and notes 3,483 — (1 ) 3,482 Corporate notes 13,946 — (19 ) 13,927 46,231 — (24 ) 46,207 Long-term investments: Corporate notes 1,506 — (7 ) 1,499 Total available-for-sale investments $ 47,737 $ — $ (31 ) $ 47,706 The following table summarizes the contractual maturities of our available-for-sale securities at December 31, 2018 (in thousands): Amortized Cost Fair Value Mature in less than one year $ 17,641 $ 17,630 Mature in one year or more $ — $ —

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment, Net [Abstract]
Schedule of property and equipment	Property and equipment consisted of the following: As of December 31, (In thousands) 2018 2017 Computer and lab equipment $ 4,923 $ 2,303 Furniture and fixtures 65 46 Leasehold improvements 930 930 Construction-in-process 21,999 4,969 Total 27,917 8,248 Less accumulated depreciation and amortization (1,574 ) (791) Property and equipment, net $ 26,343 $ 7,457

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of accrued liabilities	Accrued liabilities consisted of the following as of December 31, 2018 and 2017 : (In thousands) December 31, 2018 December 31, 2017 Accrued consulting $ 627 $ 335 Accrued research and development costs 2,509 919 Accrued other 5,012 646 Deferred rent 115 115 8,263 2,015 Less current portion (8,169 ) (1,900 ) Long-term liability (deferred rent) $ 94 $ 115

Stock-Based Awards and Benefi_2

Stock-Based Awards and Benefit Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of shares of common stock reserved for future issuance	At December 31, 2018 , shares of common stock reserved for future issuance inclusive of outstanding option shares are as follows: 2018 Equity Incentive Plan 2,596,507 2014 Employee Stock Purchase Plan 315,608 2,912,115
Summary of activity under stock option plans	A summary of activity under our stock option plans is as follows: Shares Available For Grant Shares Issuable Under Options Weighted Average Exercise Price Weighted Average Remaining ContractualTerm (In Years) Aggregate Intrinsic Value Balance, December 31, 2015 726,402 3,116,185 $7.26 8.2 $2,908,000 2012 Plan terminated (a) (307,107 ) 2016 Plan authorized (b) 3,000,000 Granted (847,683 ) 847,683 $3.48 Exercised (39,501 ) $0.57 Expired 43,818 (43,818 ) $14.52 Forfeited - stock options 312,220 (312,220 ) $7.06 Balance, December 31, 2016 2,927,650 3,568,329 $6.36 7.5 $4,353,000 2012 Plan true up retired shares (c) (26,977 ) 2016 Plan issued RSA shares (d) (250,000 ) Granted (1,208,200 ) 1,208,200 $6.62 Exercised (156,927 ) $1.98 Expired 7,267 (7,267 ) $14.54 Forfeited - stock options 38,710 (38,710 ) $6.60 Balance, December 31, 2017 1,488,450 4,573,625 $6.57 7.2 $18,745,000 2012 Plan true up retired shares (e) (56,953 ) 2016 Plan RSA forfeited on 1/23/18 (f) 26,980 2016 Plan RSU issued on 1/22/18 (g) (315,000 ) 2016 Plan true up retired shares (h) (56,636 ) 2018 Incentive Plan (i) 3,000,000 Granted (1,607,193 ) 1,607,193 $9.78 Exercised (242,031 ) $3.19 Expired 36,791 (36,791 ) $13.05 Forfeited - stock options 80,068 (80,068 ) $7.40 Balance, December 31, 2018 2,596,507 5,821,928 $7.54 7.1 $ 24,780,000 Options vested and expected to vest, December 31, 2018 5,821,928 $7.54 7.1 $ 24,780,000 Options exercisable, December 31, 2018 3,716,187 $7.01 6.1 $ 18,806,000 (a) The 2012 Equity Incentive Plan terminated in May 2016. All shares available for grant under this Plan expired. (b) The 2016 Equity Incentive Plan was adopted and approved by stockholders in May 2016. (c) True up all expired shares available for grant under the 2012 Equity Incentive Plan, which was terminated in May 2016. (d) Issued 250,000 RSA shares on January 23, 2017 under the 2016 Equity Incentive Plan. (e) True up expired shares available for grant under the 2012 Equity Incentive Plan, which was terminated in May 2016. (f) Vested 62,500 RSA shares on January 23, 2018. 26,980 shares were forfeited to cover tax liability. (g) Issued 315,000 RSU units on January 22, 2018 under the 2016 Equity Incentive Plan. (h) The 2016 Equity Incentive Plan terminated in June 2018. All shares available for grant under this Plan expired. (i) The 2018 Equity Incentive Plan was adopted and approved by stockholders in June 2018.
Schedule of restricted stock award activity	Restricted stock activity for the year ended December 31, 2018 , was as follows: Restricted Stock Award Shares Weighted Average Grant Date Fair Value Unvested balance at December 31, 2017 250,000 $6.40 Granted — — Vested (62,500 ) 6.40 Forfeited — — Unvested balance at December 31, 2018 187,500 $6.40 Restricted Stock Units Shares Weighted Average Grant Date Fair Value Unvested balance at December 31, 2017 — — Granted 315,000 $8.75 Vested — — Forfeited — — Unvested balance at December 31, 2018 315,000 $8.75
Schedule of stock-based compensation expense	Total stock-based compensation expense, related to all of our share-based payment awards, is comprised of the following: (In thousands) Years Ended December 31, 2018 2017 2016 Research and development $1,746 $1,650 $1,463 General and administrative 4,531 3,557 2,164 $6,277 $5,207 $3,627
Schedule of valuation assumptions, stock options	The relevant data used to determine the fair value of stock-based awards is as follows: Years Ended December 31, 2018 2017 2016 Stock options: Weighted average risk-free interest rate 2.62% 1.98% 1.61% Weighted average expected term (in years) 5.9 6.0 6.3 Weighted average expected volatility 59.2% 70.4% 83.4% Weighted average expected dividend yield — — — Fair value at grant date $5.58 $4.21 $2.45 Employee stock purchase plan: Weighted average risk-free interest rate 2.02% 1.04% 0.50% Weighted average expected term (in years) 0.5 0.5 0.5 Weighted average expected volatility 43.7% 56.7% 84.4% Weighted average expected dividend yield — — — Fair value at grant date $2.72 $1.73 $1.42 Restricted stock awards: Fair value at grant date — $6.40 — Restricted stock units: Fair value at grant date $8.75 — —
Schedule of valuation assumptions, employee stock purchase plan	The relevant data used to determine the fair value of stock-based awards is as follows: Years Ended December 31, 2018 2017 2016 Stock options: Weighted average risk-free interest rate 2.62% 1.98% 1.61% Weighted average expected term (in years) 5.9 6.0 6.3 Weighted average expected volatility 59.2% 70.4% 83.4% Weighted average expected dividend yield — — — Fair value at grant date $5.58 $4.21 $2.45 Employee stock purchase plan: Weighted average risk-free interest rate 2.02% 1.04% 0.50% Weighted average expected term (in years) 0.5 0.5 0.5 Weighted average expected volatility 43.7% 56.7% 84.4% Weighted average expected dividend yield — — — Fair value at grant date $2.72 $1.73 $1.42 Restricted stock awards: Fair value at grant date — $6.40 — Restricted stock units: Fair value at grant date $8.75 — —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	As of December 31, 2018 , we are obligated to make minimum lease payments under all of our operating leases as follows (in thousands): Year ending December 31, Lease Payments 2019 $ 835 2020 726 2021 459 2022 194 Thereafter — Total $ 2,214

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Differences between provision (benefit) for income taxes and income taxes at the statutory federal income tax rate	Differences between the provision (benefit) for income taxes and income taxes at the statutory federal income tax rate are as follows: (In thousands, except percentages) For the years ended December 31, 2018 2017 2016 Income tax expense (benefit) at statutory federal rate $ (10,436 ) 21.0 % $ (10,499 ) 34.0 % $ (7,651 ) 34.0 % State income tax, net of federal benefit (3,748 ) 7.5 (1,880 ) 6.1 (1,389 ) 6.2 Permanent items 13 — 63 (0.2 ) 38 (0.2 ) Research credits (1,909 ) 3.8 (1,172 ) 3.8 (970 ) 4.3 Stock-based compensation (237 ) 0.5 (122 ) 0.4 (29 ) 0.1 ASC 740-10 864 (1.7 ) 469 (1.5 ) 388 (1.7 ) Change in valuation allowance 14,949 (30.1 ) (128 ) 0.4 9,602 (42.6 ) Tax Cuts and Jobs Act — — 13,092 (42.4 ) — — Other 504 (1.0 ) 177 (0.6 ) 11 (0.1 ) Provision (benefit) for income taxes $ — — % $ — — % $ — — %
Components of deferred tax assets	The components of the deferred tax assets are as follows at December 31, 2018 and 2017 : December 31, (In thousands) 2018 2017 Deferred tax assets: Net operating loss carryforwards $ 39,579 $ 26,369 Research & development credits 3,589 3,044 Accrued expenses 893 753 Amortization and depreciation (393 ) (132 ) Stock-based compensation 6,173 4,860 Other 10 12 49,851 34,906 Valuation Allowance (49,851 ) (34,906 ) Net current deferred tax assets $ — $ —
Rollforward of changes in unrecognized tax benefits	A rollforward of changes in our unrecognized tax benefits is shown below. (In thousands) December 31, 2018 2017 2016 Balance at beginning of year $ 2,252 $ 1,698 $ 1,234 Additions based on tax positions related to the current year 944 554 464 Additions for tax positions of prior years — — — Balance at end of year $ 3,196 $ 2,252 $ 1,698

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Calculation of basic and diluted net loss per share	Basic and diluted net loss per share was calculated as follows for the years ended December 31, 2018 , 2017 and 2016: (In thousands, except per share amounts) Years Ended December 31, 2018 2017 2016 Basic and diluted net loss per share attributable to common stockholders: Numerator: Net loss attributable to common stockholders $ (49,690 ) $ (30,879 ) $ (22,499 ) Denominator: Weighted-average number of common shares outstanding, basic and diluted 31,001 25,084 19,873 Net loss per common share attributable to common stockholders, basic and diluted $ (1.60 ) $ (1.23 ) $ (1.13 )

Selected Quarterly Financial _2

Selected Quarterly Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Unaudited quarterly financial data	The following table presents selected unaudited quarterly financial data for each of the quarters in the years ended December 31, 2018 and 2017 . (In thousands, except per share amounts) 2018 2017 Quarter ended Dec. 31 Sep. 30 Jun. 30 Mar. 31 Dec. 31 Sep. 30 Jun. 30 Mar. 31 Net product revenues $ 1,326 $ 640 $ — $ — $ — $ — $ — $ — Operating costs and expenses Cost of product revenues 214 110 — — — — — — Research and development 7,756 7,477 5,820 5,346 5,142 4,877 3,866 3,780 General and administrative 9,219 6,608 5,770 4,902 4,820 3,269 3,056 2,843 Total operating cost and expenses 17,189 14,195 11,590 10,248 9,962 8,146 6,922 6,623 Loss from operations (15,863 ) (13,555 ) (11,590 ) (10,248 ) (9,962 ) (8,146 ) (6,922 ) (6,623 ) Interest and other income, net 422 518 349 277 232 256 155 131 Net loss $ (15,441 ) $ (13,037 ) $ (11,241 ) $ (9,971 ) $ (9,730 ) $ (7,890 ) $ (6,767 ) $ (6,492 ) Net loss per share, basic and diluted (1) $ (0.46 ) $ (0.39 ) $ (0.39 ) $ (0.36 ) $ (0.35 ) $ (0.29 ) $ (0.29 ) $ (0.30 ) Weighted average shares used in computing net loss per share, basic and diluted 33,708 33,601 28,619 27,986 27,915 27,400 23,409 21,516 (1) Net loss per share for each quarter is calculated as a discrete period; the sum of four quarters may not equal the calculated full year amount.

Organization and Description _2

Organization and Description of Business - Narrative (Details) $ / shares in Units, $ in Thousands	Jun. 22, 2018USD ($)$ / sharesshares	Aug. 11, 2017USD ($)$ / sharesshares	Jul. 12, 2017$ / sharesshares	Apr. 25, 2016class_of_stock$ / sharesshares	Jan. 31, 2019USD ($)$ / sharesshares	Jan. 23, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)$ / sharesshares	Apr. 30, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (USD per share) | $ / shares										$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares) | shares										100,000,000	100,000,000
Accumulated deficit										$ 161,670	$ 111,980
Net proceeds after deducting commissions and other related expenses		$ 23,198
Number of shares issued in transaction (in shares) | shares		3,314,000	3,000,000
Cash, cash equivalents, and investments in available-for-sale securities										73,900
Shares issued, price per share (USD per share) | $ / shares			$ 7.50
Net proceeds from sales of common stock										$ 49,180	52,160	$ 0
Cash sufficient to provide operations period										24 months
KindredBio Equine, Inc
Subsidiary, Sale of Stock [Line Items]
Number of classes of stock | class_of_stock				1
Common stock, par value (USD per share) | $ / shares				$ 0.0001
Common stock, shares authorized (in shares) | shares				1,000
Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses					$ 43,118	$ 43,100
IPO
Subsidiary, Sale of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses									$ 67,000
Public Stock Offering
Subsidiary, Sale of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses	$ 47,422						$ 47,400	$ 58,100			29,000
Number of shares issued in transaction (in shares) | shares	5,326,314						5,326,314
Shares issued, price per share (USD per share) | $ / shares	$ 9.50						$ 9.50
Net proceeds from sales of common stock	$ 50,600						$ 50,600
Public Stock Offering | Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses					$ 43,100
Number of shares issued in transaction (in shares) | shares					4,847,250	4,847,250
Shares issued, price per share (USD per share) | $ / shares					$ 9.50	$ 9.50
Net proceeds from sales of common stock					$ 46,049	$ 46,000
Over-allotment option
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares		314,000
Shares issued, price per share (USD per share) | $ / shares		$ 7.50
Over-allotment option | Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares					632,250	632,250
At-the-Market Offering
Subsidiary, Sale of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses							$ 1,758				$ 23,200
Number of shares issued in transaction (in shares) | shares							188,100
Net proceeds from sales of common stock							$ 1,903

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) ft² in Thousands	Aug. 07, 2017USD ($)a	Dec. 31, 2018USD ($)a	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jun. 21, 2017ft²
Property, Plant and Equipment [Line Items]
Purchase of property and equipment		$ 13,919,000	$ 5,920,000	$ 952,000
Undiscounted future minimum operating lease commitments		2,214,000
Strategic Veterinary Pharmaceuticals, Inc.
Property, Plant and Equipment [Line Items]
Area of real estate property (in sqft) | ft²					180
Purchase of property and equipment	$ 3,750,000	$ 3,750,000
Area of land (in acres) | a	8	8
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		2 years
Lab and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years
Land Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		15 years
Building and Building Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		39 years

Revenue and Cost of Product R_3

Revenue and Cost of Product Revenues - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Gross product revenues									$ 2,027
Less allowance for product returns									(61)
Net product revenues	$ 1,326	$ 640	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	1,966	$ 0	$ 0
Cost of product revenues	$ (214)	$ (110)	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	(324)	$ 0	$ 0
Gross profit									$ 1,642

Revenue and Cost of Product R_4

Revenue and Cost of Product Revenues - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
Concentration Risk [Line Items]
Product return period after expiration	90 days
Product return liability percentage	3.00%
Allowance for doubtful accounts	$ 0
Customer Concentration Risk | Revenue | Four distributors
Concentration Risk [Line Items]
Concentration risk percentage	91.00%

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measurements
Debt Securities, Available-for-sale	$ 17,630,000	$ 47,706,000
Financial assets measured at fair value on a recurring basis
Fair Value Measurements
Total financial assets	72,687,000	81,984,000
Financial liabilities measured at fair value	0	0
Financial assets measured at fair value on a recurring basis | Money market funds
Fair Value Measurements
Cash equivalents:	1,276,000	801,000
Financial assets measured at fair value on a recurring basis | Commercial paper
Fair Value Measurements
Cash equivalents:	45,332,000	31,977,000
Debt Securities, Available-for-sale	5,353,000	22,052,000
Financial assets measured at fair value on a recurring basis | Corporate notes
Fair Value Measurements
Cash equivalents:		1,500,000
Financial assets measured at fair value on a recurring basis | U.S. treasury bills
Fair Value Measurements
Cash equivalents:	500,000
Financial assets measured at fair value on a recurring basis | U.S. government agency notes
Fair Value Measurements
Debt Securities, Available-for-sale		6,746,000
Financial assets measured at fair value on a recurring basis | U.S. treasury bonds and notes
Fair Value Measurements
Cash equivalents:	7,949,000
Debt Securities, Available-for-sale		3,482,000
Financial assets measured at fair value on a recurring basis | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale	12,277,000	13,927,000
Financial assets measured at fair value on a recurring basis | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale		1,499,000
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1)
Fair Value Measurements
Total financial assets	1,776,000	4,283,000
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | Money market funds
Fair Value Measurements
Cash equivalents:	1,276,000	801,000
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | Commercial paper
Fair Value Measurements
Cash equivalents:	0	0
Debt Securities, Available-for-sale	0	0
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | Corporate notes
Fair Value Measurements
Cash equivalents:		0
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | U.S. treasury bills
Fair Value Measurements
Cash equivalents:	500,000
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | U.S. government agency notes
Fair Value Measurements
Debt Securities, Available-for-sale		0
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | U.S. treasury bonds and notes
Fair Value Measurements
Cash equivalents:	0
Debt Securities, Available-for-sale		3,482,000
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale	0	0
Financial assets measured at fair value on a recurring basis | Quoted Prices in Active Markets (Level 1) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale		0
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Total financial assets	70,911,000	77,701,000
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value Measurements
Cash equivalents:	0	0
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value Measurements
Cash equivalents:	45,332,000	31,977,000
Debt Securities, Available-for-sale	5,353,000	22,052,000
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate notes
Fair Value Measurements
Cash equivalents:		1,500,000
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | U.S. treasury bills
Fair Value Measurements
Cash equivalents:	0
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | U.S. government agency notes
Fair Value Measurements
Debt Securities, Available-for-sale		6,746,000
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | U.S. treasury bonds and notes
Fair Value Measurements
Cash equivalents:	7,949,000
Debt Securities, Available-for-sale		0
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale	12,277,000	13,927,000
Financial assets measured at fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale		1,499,000
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3)
Fair Value Measurements
Total financial assets	0	0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | Money market funds
Fair Value Measurements
Cash equivalents:	0	0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | Commercial paper
Fair Value Measurements
Cash equivalents:	0	0
Debt Securities, Available-for-sale	0	0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | Corporate notes
Fair Value Measurements
Cash equivalents:		0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | U.S. treasury bills
Fair Value Measurements
Cash equivalents:	0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | U.S. government agency notes
Fair Value Measurements
Debt Securities, Available-for-sale		0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | U.S. treasury bonds and notes
Fair Value Measurements
Cash equivalents:	0
Debt Securities, Available-for-sale		0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale	$ 0	0
Financial assets measured at fair value on a recurring basis | Unobservable Inputs (Level 3) | Corporate notes
Fair Value Measurements
Debt Securities, Available-for-sale		$ 0

Investments Summary of Investme

Investments Summary of Investments Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 17,641	$ 47,737
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11)	(31)
Fair Value	17,630	47,706
Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,641	46,231
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11)	(24)
Fair Value	17,630	46,207
Short-term investments: | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,353	22,052
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	5,353	22,052
Short-term investments: | U.S. government agency notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		6,750
Gross Unrealized Gains		0
Gross Unrealized Losses		(4)
Fair Value		6,746
Short-term investments: | U.S. treasury bonds and notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		3,483
Gross Unrealized Gains		0
Gross Unrealized Losses		(1)
Fair Value		3,482
Short-term investments: | Corporate Note Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,288	13,946
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11)	(19)
Fair Value	$ 12,277	13,927
Short-term investments: | Corporate notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,506
Gross Unrealized Gains		0
Gross Unrealized Losses		(7)
Fair Value		$ 1,499

Investments Maturities of Avail

Investments Maturities of Available-for-Sale Securities (Details) $ in Thousands	Dec. 31, 2018USD ($)
Amortized Cost
Mature in less than one year	$ 17,641
Mature in one year or more	0
Fair Value
Mature in less than one year	17,630
Mature in one year or more	$ 0

Property and Equipment, Net Sch

Property and Equipment, Net Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 27,917	$ 8,248
Less accumulated depreciation and amortization	(1,574)	(791)
Property and equipment, net	26,343	7,457
Computer and lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,923	2,303
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	65	46
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	930	930
Construction-in-process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 21,999	$ 4,969

Property and Equipment, Net Nar

Property and Equipment, Net Narrative (Details)	Aug. 07, 2017USD ($)a	Dec. 31, 2018USD ($)a	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Property, Plant and Equipment [Line Items]
Purchase of property and equipment		$ 13,919,000	$ 5,920,000	$ 952,000
Property and equipment, gross		27,917,000	8,248,000
Depreciation and amortization expense		805,000	475,000	$ 155,000
Construction-in-process
Property, Plant and Equipment [Line Items]
Purchase of property and equipment		18,249,000
Property and equipment, gross		21,999,000	$ 4,969,000
Strategic Veterinary Pharmaceuticals, Inc.
Property, Plant and Equipment [Line Items]
Purchase of property and equipment	$ 3,750,000	$ 3,750,000
Area of land (in acres) | a	8	8

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued consulting	$ 627	$ 335
Accrued research and development costs	2,509	919
Accrued other	5,012	646
Deferred rent	115	115
Accrued liabilities	8,263	2,015
Less current portion	(8,169)	(1,900)
Long-term liability (deferred rent)	$ 94	$ 115

Stockholders' Equity (Details)

Stockholders' Equity (Details)	Jun. 22, 2018USD ($)$ / sharesshares	Aug. 11, 2017USD ($)$ / sharesshares	Jul. 12, 2017USD ($)$ / sharesshares	Dec. 19, 2016USD ($)	Jan. 31, 2019USD ($)$ / sharesshares	Jan. 23, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)$ / sharesshares	Jan. 31, 2018USD ($)	Jan. 31, 2015USD ($)	Apr. 30, 2014USD ($)	Jun. 30, 2017USD ($)shares	Dec. 31, 2018USD ($)vote$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	May 31, 2018USD ($)	Dec. 31, 2015shares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares												10,000,000
Preferred stock, par value (in dollars per share) | $ / shares												$ 0.0001
Number of common shares authorized (in shares) | shares												100,000,000	100,000,000
Common stock, par value (USD per share) | $ / shares												$ 0.0001	$ 0.0001
Exercise of common stock options (in shares) | shares												242,031	156,927	39,501
Exercise of stock options and purchase of ESPP shares												$ 635,000	$ 311,000	$ 23,000
Common stock, shares outstanding (in shares) | shares												33,948,254	28,182,563
Maximum dollar amount of equity and debt securities offered								$ 150,000,000	$ 150,000,000
Maximum aggregate offering price of common stock sold under agreement				$ 30,000,000
Number of shares issued in transaction (in shares) | shares		3,314,000	3,000,000
Net proceeds after deducting commissions and other related expenses		$ 23,198,000
Shares issued, price per share (USD per share) | $ / shares			$ 7.50
Net proceeds from sales of common stock												$ 49,180,000	$ 52,160,000	$ 0
Stock issued during period		$ 24,855,000	$ 22,500,000
Common Stock
Class of Stock [Line Items]
Number of voting rights | vote												1
Exercise of common stock options (in shares) | shares												231,000	157,000	40,000
Common stock issued under ESPP (in shares) | shares												46,850	43,561	40,429
Proceeds from ESPP												$ 352,000	$ 201,000	$ 139,000
Common stock, shares outstanding (in shares) | shares												33,948,000	28,183,000	19,916,000		19,836,000
Common Stock | Employee | Stock options
Class of Stock [Line Items]
Exercise of common stock options (in shares) | shares												231,407	156,927	39,501
Exercise of stock options and purchase of ESPP shares												$ 635,000	$ 311,000	$ 23,000
FBR Capital Markets & Co.
Class of Stock [Line Items]
Commission percentage of gross proceeds				3.00%
Number of shares issued in transaction (in shares) | shares											4,501,985
Payments for commissions and fees											$ 906,000
Payments of stock issuance costs											132,000
Net proceeds after deducting commissions and other related expenses											$ 28,962,000
Over-allotment option
Class of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares		314,000
Shares issued, price per share (USD per share) | $ / shares		$ 7.50
Stock issued during period		$ 2,355,000
At-the-Market Offering
Class of Stock [Line Items]
Shares Available For Issuance															$ 50,000,000
Number of shares issued in transaction (in shares) | shares							188,100
Net proceeds after deducting commissions and other related expenses							$ 1,758,000						23,200,000
Net proceeds from sales of common stock							$ 1,903,000
Stock issued during period												1,758,000	28,962,000
At-the-Market Offering | Common Stock
Class of Stock [Line Items]
Payments of stock issuance costs												$ 145,000	1,038,000
Stock issued during period													1,000
Public Stock Offering
Class of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares	5,326,314						5,326,314
Net proceeds after deducting commissions and other related expenses	$ 47,422,000						$ 47,400,000			$ 58,100,000			$ 29,000,000
Shares issued, price per share (USD per share) | $ / shares	$ 9.50						$ 9.50
Net proceeds from sales of common stock	$ 50,600,000						$ 50,600,000
Subsequent Event
Class of Stock [Line Items]
Net proceeds after deducting commissions and other related expenses					$ 43,118,000	$ 43,100,000
Subsequent Event | Over-allotment option
Class of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares					632,250	632,250
Subsequent Event | Public Stock Offering
Class of Stock [Line Items]
Number of shares issued in transaction (in shares) | shares					4,847,250	4,847,250
Net proceeds after deducting commissions and other related expenses					$ 43,100,000
Shares issued, price per share (USD per share) | $ / shares					$ 9.50	$ 9.50
Net proceeds from sales of common stock					$ 46,049,000	$ 46,000,000
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares												100,000
Undesignated
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares												9,900,000

Stock-Based Awards and Benefi_3

Stock-Based Awards and Benefit Plan - Narrative (Details)

Jun. 26, 2018

Jun. 22, 2018

Jan. 22, 2018USD ($)shares

Jan. 23, 2017USD ($)employeeshares

Nov. 04, 2012shares

Jun. 30, 2018shares

May 31, 2016shares

Dec. 31, 2014USD ($)shares

Dec. 31, 2018USD ($)$ / sharesshares

Dec. 31, 2017USD ($)$ / sharesshares

Dec. 31, 2016USD ($)$ / sharesshares

Dec. 31, 2015shares

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

2,912,115

Number of options outstanding (in shares)

5,821,928

4,573,625

3,568,329

3,116,185

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

2,596,507

1,488,450

2,927,650

726,402

Common stock reserved for future issuance (in shares)

315,608

Aggregate intrinsic value of stock options exercised | $

$ 2,261,000

$ 911,000

$ 117,000

Exercise of stock options and purchase of ESPP shares | $

$ 635,000

$ 311,000

$ 23,000

Grants in period, weighted average grant date fair value (USD per share) | $ / shares

$ 5.58

$ 4.21

$ 2.45

Stock-based compensation expense | $

$ 6,277,000

$ 5,207,000

$ 3,627,000

Unrecognized stock-based compensation expense | $

$ 9,093,000

Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants in period, weighted average grant date fair value (USD per share) | $ / shares

$ 5.58

$ 4.21

$ 2.45

Recognition period (in years)

2 years 9 months 11 days

Restricted Stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period (in years)

1 year

Restricted stock granted (in shares)

250,000

0

0

0

Restricted stock unvested (in shares)

187,500

250,000

Number of employees awards | employee

4

Vesting rights percentage

25.00%

Stock-based compensation expense | $

$ 2,756,000

$ 1,600,000

Unrecognized stock-based compensation expense | $

$ 2,933,000

Recognition period (in years)

2 years 9 months 11 days

Restricted Stock Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Restricted stock granted (in shares)

315,000

315,000

Restricted stock unvested (in shares)

315,000

0

2012 Equity Incentive Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

4,000,000

2012 Equity Incentive Plan | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Expiration period (in years)

10 years

Number of options outstanding (in shares)

3,041,999

2014 Employee Stock Purchase Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

315,608

2014 Employee Stock Purchase Plan | Employee stock purchase plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

200,000

Percent of purchase price of common stock

85.00%

Offering period (in months)

6 months

Maximum number of shares per employee (in shares)

2,000

Maximum value of shares per employee | $

$ 25,000

Weighted average grant date fair value (USD per share) | $ / shares

$ 2.72

Accrued employee benefits | $

$ 47,000

$ 27,000

2014 Employee Stock Purchase Plan | Minimum | Employee stock purchase plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

200,000

2014 Employee Stock Purchase Plan | Maximum | Employee stock purchase plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

500,000

2016 Equity Incentive Plan | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Expiration period (in years)

10 years

Shares reserved for future issuance (in shares)

3,000,000

Number of options outstanding (in shares)

2,376,436

Percent of purchase price of common stock

100.00%

Purchase price of common stock if ownership percentage surpasses threshold, percent

110.00%

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

0

2016 Equity Incentive Plan | 10% Stock Options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Expiration period (in years)

5 years

2016 Equity Incentive Plan | Restricted Stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Restricted stock granted (in shares)

187,500

250,000

2016 Equity Incentive Plan | Restricted Stock Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Restricted stock granted (in shares)

315,000

Restricted stock unvested (in shares)

315,000

2016 Equity Incentive Plan | Minimum | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period (in years)

1 year

2016 Equity Incentive Plan | Maximum | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period (in years)

4 years

2018 Equity Incentive Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares reserved for future issuance (in shares)

2,596,507

2018 Equity Incentive Plan | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Expiration period (in years)

10 years

5 years

Shares reserved for future issuance (in shares)

3,000,000

Number of options outstanding (in shares)

403,493

Percent of purchase price of common stock

100.00%

Purchase price of common stock if ownership percentage surpasses threshold, percent

110.00%

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

2,596,507

2018 Equity Incentive Plan | Minimum | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period (in years)

1 year

2018 Equity Incentive Plan | Maximum | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period (in years)

4 years

Common Stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Common stock issued under ESPP (in shares)

46,850

43,561

40,429

Common Stock | 2014 Employee Stock Purchase Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Common stock issued under ESPP (in shares)

184,392

Optionee | 2016 Equity Incentive Plan | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Ownership percentage by noncontrolling Owners

10.00%

Optionee | 2018 Equity Incentive Plan | Stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Ownership percentage by noncontrolling Owners

10.00%

Stock-Based Awards and Benefi_4

Stock-Based Awards and Benefit Plan - Reserved Shares (Details)	Dec. 31, 2018shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	2,912,115
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	2,596,507
2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	315,608

Stock-Based Awards and Benefi_5

Stock-Based Awards and Benefit Plan - Stock Option Plan Activity Summary (Details) - USD ($)	Jan. 23, 2018	Jan. 22, 2018	Jan. 23, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Number of shares available for grant, beginning balance (in shares)				1,488,450	2,927,650	726,402
Number of shares issuable under options, beginning balance (in shares)				4,573,625	3,568,329	3,116,185
Granted (in shares)				(1,607,193)	(1,208,200)	(847,683)
Exercised (in shares)				(242,031)	(156,927)	(39,501)
Expired (in shares)				(36,791)	(7,267)	(43,818)
Forfeited - stock options (in shares)				(80,068)	(38,710)	(312,220)
Number of shares available for grant, ending balance (in shares)				2,596,507	1,488,450	2,927,650	726,402
Number of shares issuable under options, ending balance (in shares)				5,821,928	4,573,625	3,568,329	3,116,185
Weighted Average Exercise Price
Granted (USD per share)				$ 9.78	$ 6.62	$ 3.48
Exercised (USD per share)				3.19	1.98	0.57
Expired (USD per share)				13.05	14.54	14.52
Forfeited - stock options (USD per share)				7.40	6.60	7.06
Outstanding (USD per share)				$ 7.54	$ 6.57	$ 6.36	$ 7.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Term (in years)				7 years 26 days	7 years 2 months 16 days	7 years 6 months	8 years 2 months 12 days
Aggregate Intrinsic Value				$ 24,780,000	$ 18,745,000	$ 4,353,000	$ 2,908,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Options vested and expected to vest, shares issuable under options (in shares)				5,821,928
Options vested and expected to vest, weighted average exercise price (USD per share)				$ 7.54
Options vested and expected to vest, weighted average remaining contractual term (in years)				7 years 26 days
Options vested and expected to vest, aggregate intrinsic value				$ 24,780,000
Options exercisable, shares issuable under options (in shares)				3,716,187
Options exercisable, weighted average exercise price (USD per share)				$ 7.01
Options exercisable, weighted average remaining contractual term (in years)				6 years 1 month 6 days
Options exercisable, aggregate intrinsic value				$ 18,806,000
2012 Equity Incentive Plan
Shares
2012 Plan terminated (in shares)						(307,107)
2012 Plan true up retired shares (in shares)				(56,953)	(26,977)
2016 Equity Incentive Plan
Shares
2016 Plan authorized (in shares)						3,000,000
2012 Plan true up retired shares (in shares)				(56,636)
Restricted Stock
Shares
2016 Plan RSA forfeited shares (in shares)	62,500
2016 Plan issued RSA shares (in shares)			(250,000)	0	0	0
Restricted Stock | 2016 Equity Incentive Plan
Shares
2016 Plan RSA forfeited shares (in shares)				26,980
2016 Plan issued RSA shares (in shares)				(187,500)	(250,000)
Restricted Stock Units (RSUs)
Shares
2016 Plan issued RSA shares (in shares)		(315,000)		(315,000)
Restricted Stock Units (RSUs) | 2016 Equity Incentive Plan
Shares
2016 Plan issued RSA shares (in shares)				(315,000)
Stock options | 2012 Equity Incentive Plan
Shares
Number of shares issuable under options, ending balance (in shares)				3,041,999
Stock options | 2016 Equity Incentive Plan
Shares
Number of shares available for grant, ending balance (in shares)				0
Number of shares issuable under options, ending balance (in shares)				2,376,436
Stock options | 2018 Equity Incentive Plan
Shares
2018 Incentive Plan (in share)				3,000,000
Number of shares available for grant, ending balance (in shares)				2,596,507
Number of shares issuable under options, ending balance (in shares)				403,493

Stock-Based Awards and Benefi_6

Stock-Based Awards and Benefit Plan - Restricted Stock (Details) - $ / shares	Jan. 22, 2018	Jan. 23, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock
Shares
Unvested balance at December 31, 2016 (in shares)			250,000
Granted (in shares)		250,000	0	0	0
Vested (in shares)			(62,500)
Forfeited (in shares)			0
Unvested balance at December 31, 2017 (in shares)			187,500	250,000
Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2016 (in USD per share)			$ 6.40
Granted (in USD per share)			0	$ 6.40	$ 0
Vested (in USD per share)			6.40
Forfeited (in USD per share)			0
Unvested balance at December 31, 2017 (in USD per share)			$ 6.40	$ 6.40
Restricted Stock Units (RSUs)
Shares
Unvested balance at December 31, 2016 (in shares)			0
Granted (in shares)	315,000		315,000
Vested (in shares)			0
Forfeited (in shares)			0
Unvested balance at December 31, 2017 (in shares)			315,000	0
Weighted Average Grant Date Fair Value
Unvested balance at December 31, 2016 (in USD per share)			$ 0
Granted (in USD per share)			8.75	$ 0	$ 0
Vested (in USD per share)			0
Forfeited (in USD per share)			0
Unvested balance at December 31, 2017 (in USD per share)			$ 8.75	$ 0

Stock-Based Awards and Benefi_7

Stock-Based Awards and Benefit Plan - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,277	$ 5,207	$ 3,627
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,746	1,650	1,463
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4,531	$ 3,557	$ 2,164

Stock-Based Awards and Benefi_8

Stock-Based Awards and Benefit Plan - Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value at grant date, stock options (in USD per share)	$ 5.58	$ 4.21	$ 2.45
Stock options:
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average risk-free interest rate	2.62%	1.98%	1.61%
Weighted average expected term (in years)	5 years 11 months 1 day	6 years	6 years 3 months 18 days
Weighted average expected volatility	59.20%	70.40%	83.40%
Weighted average expected dividend yield	0.00%	0.00%	0.00%
Fair value at grant date, stock options (in USD per share)	$ 5.58	$ 4.21	$ 2.45
Employee stock purchase plan:
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average risk-free interest rate	2.02%	1.04%	0.50%
Weighted average expected term (in years)	6 months	6 months	6 months
Weighted average expected volatility	43.70%	56.70%	84.40%
Weighted average expected dividend yield	0.00%	0.00%	0.00%
Fair value at grant date, other options (in USD per share)	$ 2.72	$ 1.73	$ 1.42
Restricted stock awards:
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value at grant date, other options (in USD per share)	0	6.40	0
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value at grant date, other options (in USD per share)	$ 8.75	$ 0	$ 0

Commitments and Contingencies_2

Commitments and Contingencies (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Oct. 31, 2018ft²	Mar. 31, 2018ft²	Jun. 30, 2017ft²	Jun. 01, 2017ft²	Apr. 30, 2017ft²	Feb. 28, 2017ft²	Oct. 31, 2016ft²	Feb. 29, 2016ft²	Nov. 30, 2015ft²	Aug. 31, 2015ft²	Jan. 31, 2015ft²	Apr. 30, 2014ft²
Property Subject to or Available for Operating Lease [Line Items]
Rent expense		$ 814	$ 679	$ 522
Purchase agreement amount	$ 3,800
Purchase agreement commitment	7 years
Purchase obligation		16,500
Equipment purchase costs		3,286
Equipment expenses		588
Lease Payments
2,019		835
2,020		726
2,021		459
2,022		194
2,023		0
Total		$ 2,214
Building Improvements [Member]
Property Subject to or Available for Operating Lease [Line Items]
Area of real estate property (in sqft) | ft²						16,500
Property Subject to Operating Lease | Laboratory space
Property Subject to or Available for Operating Lease [Line Items]
Area of real estate property (in sqft) | ft²								11,476								2,145
Additional area of real estate property (in sqft) | ft²					5,613					721	2,326	3,599	123	131	2,431
Property Subject to Operating Lease | Office Space
Property Subject to or Available for Operating Lease [Line Items]
Area of real estate property (in sqft) | ft²									6,900					3,126		6,900
Additional area of real estate property (in sqft) | ft²							1,190

Restructuring Plan (Details)

Restructuring Plan (Details) $ in Thousands	Jan. 11, 2016position	Mar. 31, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Restructuring and Related Activities [Abstract]
Number of positions eliminated	18
Percentage of workforce reduced	31.00%
Entity number of employees	39
Restructuring costs | $		$ 655	$ 0	$ 0	$ 655

Income Taxes - Reconciliation S

Income Taxes - Reconciliation Statutory Federal Income Tax to Effective Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense (benefit) at statutory federal rate	$ (10,436)	$ (10,499)	$ (7,651)
State income tax, net of federal benefit	(3,748)	(1,880)	(1,389)
Permanent items	13	63	38
Research credits	(1,909)	(1,172)	(970)
Stock-based compensation	(237)	(122)	(29)
ASC 740-10	864	469	388
Change in valuation allowance	14,949	(128)	9,602
Tax Cuts and Jobs Act	0	13,092	0
Other	504	177	11
Provision (benefit) for income taxes	$ 0	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax expense (benefit) at statutory federal rate	21.00%	34.00%	34.00%
State income tax, net of federal benefit	7.50%	6.10%	6.20%
Permanent items	0.00%	(0.20%)	(0.20%)
Research credits	3.80%	3.80%	4.30%
Stock-based compensation	0.50%	0.40%	0.10%
ASC 740-10	(1.70%)	(1.50%)	(1.70%)
Change in valuation allowance	(30.10%)	0.40%	(42.60%)
Tax Cuts and Jobs Act	0.00%	(42.40%)	0.00%
Other	(1.00%)	(0.60%)	(0.10%)
Provision (benefit) for income taxes	0.00%	0.00%	0.00%

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 39,579	$ 26,369
Research & development credits	3,589	3,044
Accrued expenses	893	753
Amortization and depreciation	(393)	(132)
Stock-based compensation	6,173	4,860
Other	10	12
Deferred tax assets, gross	49,851	34,906
Valuation Allowance	(49,851)	(34,906)
Net current deferred tax assets	$ 0	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Net deferred tax assets	$ 49,851,000	$ 34,906,000
Ownership change percentage limitation for operating soss and development tax credits over a three year period	50.00%
Ownership change duration limitation for operating soss and development tax credits over a three year period	3 years
Uncertain tax position liability percentage	50.00%
Unrecognized tax benefits that would impact the effective tax rate	$ 2,893,000
Income tax examination, penalties and interest accrued	$ 0	$ 0
Unrecognized tax benefit period	12 months
Income tax expense (benefit) at statutory federal rate	21.00%	35.00%
Income tax examination, penalties and interest expense	$ 0	$ 0	$ 0
Reduction in deferred tax asset as a result of the Tax Cuts and Jobs Act	13,100,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryovers	139,843,000
Federal | Research tax credit carryover
Operating Loss Carryforwards [Line Items]
Tax credit carryovers	3,625,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryovers	139,763,000
State | Research tax credit carryover
Operating Loss Carryforwards [Line Items]
Tax credit carryovers	$ 3,617,000

Income Taxes - Rollforward of C

Income Taxes - Rollforward of Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 2,252	$ 1,698	$ 1,234
Additions based on tax positions related to the current year	944	554	464
Additions for tax positions of prior years	0	0	0
Balance at end of year	$ 3,196	$ 2,252	$ 1,698

Net Loss Per Share (Details)

Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss attributable to common stockholders	$ (15,441)	$ (13,037)	$ (11,241)	$ (9,971)	$ (9,730)	$ (7,890)	$ (6,767)	$ (6,492)	$ (49,690)	$ (30,879)	$ (22,499)
Denominator:
Weighted-average number of common shares outstanding, basic and diluted (in shares)	33,708,000	33,601,000	28,619,000	27,986,000	27,915,000	27,400,000	23,409,000	21,516,000	31,001,000	25,084,000	19,873,000
Net loss per common share attributable to common stockholders, basic and diluted (USD per share)	$ (0.46)	$ (0.39)	$ (0.39)	$ (0.36)	$ (0.35)	$ (0.29)	$ (0.29)	$ (0.30)	$ (1.60)	$ (1.23)	$ (1.13)
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS computation (in shares)									5,821,928	4,573,625	3,568,329
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS computation (in shares)									187,500	250,000
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS computation (in shares)									315,000

Employee Savings Plan (Details)

Employee Savings Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Maximum contributions per employee, percent of salary	90.00%
Employer matching contribution, percent of match	50.00%
Employer matching contribution, percent of participant's compensation	6.00%
Contributions during the year	$ 292	$ 149	$ 101
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of match	3.00%

Selected Quarterly Financial _3

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,326	$ 640	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 1,966	$ 0	$ 0
Operating costs and expenses
Cost of product revenues	214	110	0	0	0	0	0	0		324	0	0
Research and development	7,756	7,477	5,820	5,346	5,142	4,877	3,866	3,780		26,399	17,665	13,861
General and administrative	9,219	6,608	5,770	4,902	4,820	3,269	3,056	2,843		26,499	13,988	8,308
Restructuring costs									$ 655	0	0	655
Total operating expenses	17,189	14,195	11,590	10,248	9,962	8,146	6,922	6,623		53,222	31,653	22,824
Loss from operations	(15,863)	(13,555)	(11,590)	(10,248)	(9,962)	(8,146)	(6,922)	(6,623)		(51,256)	(31,653)	(22,824)
Interest and other income, net	422	518	349	277	232	256	155	131		1,566	774	325
Net loss	$ (15,441)	$ (13,037)	$ (11,241)	$ (9,971)	$ (9,730)	$ (7,890)	$ (6,767)	$ (6,492)		$ (49,690)	$ (30,879)	$ (22,499)
Net loss per share, basic and diluted (USD per share)	$ (0.46)	$ (0.39)	$ (0.39)	$ (0.36)	$ (0.35)	$ (0.29)	$ (0.29)	$ (0.30)		$ (1.60)	$ (1.23)	$ (1.13)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	33,708	33,601	28,619	27,986	27,915	27,400	23,409	21,516		31,001	25,084	19,873

Subsequent Events - (Details)

Subsequent Events - (Details) $ / shares in Units, $ in Thousands	Feb. 01, 2019$ / sharesshares	Jun. 22, 2018USD ($)$ / sharesshares	Aug. 11, 2017USD ($)$ / sharesshares	Jul. 12, 2017$ / sharesshares	Jan. 31, 2019USD ($)$ / sharesshares	Jan. 23, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)$ / sharesshares	Apr. 30, 2014USD ($)	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares) | shares			3,314,000	3,000,000
Shares issued, price per share (USD per share) | $ / shares				$ 7.50
Net proceeds from sales of common stock | $									$ 49,180	$ 52,160	$ 0
Net proceeds after deducting commissions and other related expenses | $			$ 23,198
Common stock, par value (USD per share) | $ / shares									$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares) | shares									100,000,000	100,000,000
Subsequent Event
Subsequent Event [Line Items]
Net proceeds after deducting commissions and other related expenses | $					$ 43,118	$ 43,100
Public Stock Offering
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares) | shares		5,326,314					5,326,314
Shares issued, price per share (USD per share) | $ / shares		$ 9.50					$ 9.50
Net proceeds from sales of common stock | $		$ 50,600					$ 50,600
Net proceeds after deducting commissions and other related expenses | $		$ 47,422					$ 47,400	$ 58,100		$ 29,000
Public Stock Offering | Subsequent Event
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares) | shares					4,847,250	4,847,250
Shares issued, price per share (USD per share) | $ / shares					$ 9.50	$ 9.50
Net proceeds from sales of common stock | $					$ 46,049	$ 46,000
Net proceeds after deducting commissions and other related expenses | $					$ 43,100
Over-allotment option
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares) | shares			314,000
Shares issued, price per share (USD per share) | $ / shares			$ 7.50
Over-allotment option | Subsequent Event
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares) | shares					632,250	632,250
Centaur Biopharmaceutical Services | Subsequent Event
Subsequent Event [Line Items]
Number of classes of stock	1
Common stock, par value (USD per share) | $ / shares	$ 0.0001
Common stock, shares authorized (in shares) | shares	1,000