TRACON Pharmaceuticals (TCON) 10-Q 5 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Cover [Abstract]
Entity Registrant Name	TRACON Pharmaceuticals, Inc.
Entity Central Index Key	0001394319
Document Type	10-Q
Document Period End Date	Jun. 30, 2020
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		8,498,702
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	TCON
Entity Shell Company	false
Entity File Number	001-36818
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	34-2037594
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity Address, Address Line One	4350 La Jolla Village Drive
Entity Address, Address Line Two	Suite 800
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92122
City Area Code	858
Local Phone Number	550-0780
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 14,453	$ 16,412
Prepaid and other assets	503	848
Total current assets	14,956	17,260
Property and equipment, net	16	23
Other assets	678	838
Total assets	15,650	18,121
Current liabilities:
Accounts payable and accrued expenses	6,583	7,875
Accrued compensation and related expenses	906	1,355
Long-term debt, current portion	1,746	2,604
Total current liabilities	9,235	11,834
Other long-term liabilities	651	850
Long-term debt, less current portion	2,761	2,739
Commitments and contingencies (Note 4)
Stockholders’ equity:
Preferred stock, $0.001 par value, authorized shares — 10,000,000 at June 30, 2020 and December 31, 2019; issued and outstanding shares — none
Common stock, $0.001 par value; authorized shares — 20,000,000 at June 30, 2020 and December 31, 2019; issued and outstanding shares — 7,773,815 and 4,051,187 at June 30, 2020 and December 31, 2019, respectively	8	4
Additional paid-in capital	173,801	165,028
Accumulated deficit	(170,806)	(162,334)
Total stockholders’ equity	3,003	2,698
Total liabilities and stockholders’ equity	$ 15,650	$ 18,121

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	7,773,815	4,051,187
Common stock, shares outstanding	7,773,815	4,051,187

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 2,218	$ 4,347	$ 4,216	$ 9,561
General and administrative	2,096	1,893	3,982	3,842
Total operating expenses	4,314	6,240	8,198	13,403
Loss from operations	(4,314)	(6,240)	(8,198)	(13,403)
Other expense:
Interest expense, net	(138)	(87)	(271)	(133)
Other income (expense), net	1	1	(3)	(3)
Total other expense	(137)	(86)	(274)	(136)
Net loss	$ (4,451)	$ (6,326)	$ (8,472)	$ (13,539)
Net loss per share, basic and diluted	$ (0.70)	$ (2.11)	$ (1.47)	$ (4.53)
Weighted-average shares outstanding, basic and diluted	6,385,562	2,992,936	5,778,456	2,991,079

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ 21,442	$ 3	$ 161,099	$ (139,660)
Balance (in Shares) at Dec. 31, 2018		2,987,182
Increase (Decrease) in Shareholders' Equity
Issuance of common stock under equity plans	(20)		(20)
Issuance of common stock under equity plans (in shares)		2,738
Stock-based compensation expense	596		596
Net loss	(7,213)			(7,213)
Balance at Mar. 31, 2019	14,805	$ 3	161,675	(146,873)
Balance (in Shares) at Mar. 31, 2019		2,989,920
Balance at Dec. 31, 2018	21,442	$ 3	161,099	(139,660)
Balance (in Shares) at Dec. 31, 2018		2,987,182
Increase (Decrease) in Shareholders' Equity
Net loss	(13,539)
Balance at Jun. 30, 2019	8,919	$ 3	162,115	(153,199)
Balance (in Shares) at Jun. 30, 2019		2,993,793
Balance at Mar. 31, 2019	14,805	$ 3	161,675	(146,873)
Balance (in Shares) at Mar. 31, 2019		2,989,920
Increase (Decrease) in Shareholders' Equity
Issuance of common stock under equity plans	24		24
Issuance of common stock under equity plans (in shares)		3,873
Stock-based compensation expense	416		416
Net loss	(6,326)			(6,326)
Balance at Jun. 30, 2019	8,919	$ 3	162,115	(153,199)
Balance (in Shares) at Jun. 30, 2019		2,993,793
Balance at Dec. 31, 2019	2,698	$ 4	165,028	(162,334)
Balance (in Shares) at Dec. 31, 2019		4,051,187
Increase (Decrease) in Shareholders' Equity
Issuance of common stock under equity plans	(6)		(6)
Issuance of common stock under equity plans (in shares)		2,078
Stock-based compensation expense	267		267
Issuances of common stock, net of offering costs	3,720	$ 1	3,719
Issuances of common stock, net of offering costs (in shares)		1,344,673
Issuance of common stock in exchange for services	126		126
Issuance of common stock in exchange for services (in shares)		100,000
Net loss	(4,021)			(4,021)
Balance at Mar. 31, 2020	2,784	$ 5	169,134	(166,355)
Balance (in Shares) at Mar. 31, 2020		5,497,938
Balance at Dec. 31, 2019	2,698	$ 4	165,028	(162,334)
Balance (in Shares) at Dec. 31, 2019		4,051,187
Increase (Decrease) in Shareholders' Equity
Net loss	(8,472)
Balance at Jun. 30, 2020	3,003	$ 8	173,801	(170,806)
Balance (in Shares) at Jun. 30, 2020		7,773,815
Balance at Mar. 31, 2020	2,784	$ 5	169,134	(166,355)
Balance (in Shares) at Mar. 31, 2020		5,497,938
Increase (Decrease) in Shareholders' Equity
Issuance of common stock under equity plans	5		5
Issuance of common stock under equity plans (in shares)		2,450
Stock-based compensation expense	263		263
Issuances of common stock, net of offering costs	4,402	$ 3	4,399
Issuances of common stock, net of offering costs (in shares)		2,273,427
Net loss	(4,451)			(4,451)
Balance at Jun. 30, 2020	$ 3,003	$ 8	$ 173,801	$ (170,806)
Balance (in Shares) at Jun. 30, 2020		7,773,815

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (8,472)	$ (13,539)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	530	1,012
Common stock issued for services	95
Depreciation and amortization	7	13
Noncash interest	72	123
Amortization of debt discount	25	43
Amortization of premium/discount on short-term investments		(52)
Lease asset amortization and liability accretion, net	(9)
Changes in assets and liabilities:
Prepaid expenses and other assets	376	905
Accounts payable and accrued expenses	(1,322)	(802)
Accrued compensation and related expenses	(449)	(527)
Net cash used in operating activities	(9,147)	(12,824)
Cash flows from investing activities
Purchases of available-for-sale short-term investments		(4,980)
Proceeds from the maturity of available-for-sale short-term investments		19,000
Net cash provided by investing activities		14,020
Cash flows from financing activities
Repayment of long-term debt	(933)
Proceeds from sale of common stock, net of offering costs	8,122
Proceeds from issuance of common stock under equity plans	5	24
Payment of tax withholdings related to net share settlements of vested restricted stock awards	(6)	(20)
Net cash provided by financing activities	7,188	4
Change in cash and cash equivalents	(1,959)	1,200
Cash and cash equivalents at beginning of period	16,412	25,136
Cash and cash equivalents at end of period	$ 14,453	$ 26,336

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Organization And Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies Organization and Business TRACON Pharmaceuticals, Inc. (formerly Lexington Pharmaceuticals, Inc.) (TRACON or the Company) was incorporated in the state of Delaware on October 28, 2004. TRACON is a clinical stage biopharmaceutical company focused on the development and commercialization of novel targeted therapeutics for cancer. The Company’s product development platform, which emphasizes capital efficiency, also provides to ex-U.S. companies a rapid and capital-efficient U.S. drug development solution that includes U.S. and European Union (EU) clinical development expertise and U.S. commercialization expertise. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, TRACON Pharma Limited and TRACON Pharma International Limited, which were formed in September 2015 and January 2019, respectively, and are currently inactive. All significant intercompany accounts and transactions have been eliminated. Basis of Presentation As of June 30, 2020, the Company has devoted substantially all of its efforts to product development, raising capital, and building infrastructure and has not realized revenues from its planned principal operations. The Company has incurred operating losses since inception. As of June 30, 2020, the Company had an accumulated deficit of $170.8 million. The Company anticipates that it will continue to incur net losses into the foreseeable future as it continues the development and commercialization of its product candidates and works to develop additional product candidates through research and development programs. At June 30, 2020, the Company had cash and cash equivalents of $14.5 million. Based on the Company’s current business plan, management believes that there is substantial doubt as to whether existing cash and cash equivalents will be sufficient to meet its obligations as they become due within one year from the date these financial statements are issued. The Company’s ability to execute its operating plan through the second quarter of 2021 and beyond depends on its ability to obtain additional funding through equity offerings, debt financings, or potential licensing and collaboration arrangements. The accompanying unaudited condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business. However, the Company’s current working capital, anticipated operating expenses and net losses, and the uncertainties surrounding its ability to raise additional capital as needed, as discussed below, raise substantial doubt about its ability to continue as a going concern for a period of one year following the date that these financial statements are issued. The unaudited condensed consolidated financial statements do not include any adjustments for the recovery and classification of assets or the amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. The Company plans to continue to fund its losses from operations through its existing cash and cash equivalents, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements. In addition, the Company may fund its losses from operations through the common stock purchase agreement the Company entered into with Aspire Capital Fund, LLC (Aspire Capital) in October 2019, as amended in April 2020, for the purchase of up to $15.0 million of the Company’s common stock over the 30 month period of the purchase agreement, $11.7 million of which remained available for sale as of June 30, 2020 and/or the Capital on Demand TM Unaudited Interim Financial Information The unaudited condensed consolidated financial statements as of June 30, 2020, and for the three and six months ended June 30, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC), and with accounting principles generally accepted in the United States (GAAP) applicable to interim financial statements. These unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019, included in its Annual Report on Form 10-K filed with the SEC on February 28, 2020. Reverse Stock Split On November 7, 2019, the Company filed an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-10 reverse stock split of its common stock (the reverse stock split). The reverse stock split applied to all of the Company’s outstanding shares of common stock and therefore did not affect any stockholder’s relative ownership percentage. In connection with the reverse stock split, the number of authorized shares of common stock was reduced from 200,000,000 shares to 20,000,000 shares. The number of authorized shares of preferred stock remained (and remains) unchanged at 10,000,000 shares. The par value of the common stock was not adjusted as a result of the reverse stock split. All of the Company’s stock options, warrants and restricted stock units outstanding immediately prior to the reverse stock split were proportionately adjusted. All share and price per share data for all periods presented in these consolidated financial statements and notes thereto have been adjusted to give effect to the reverse stock split, including retrospectively where applicable. Risks and Uncertainties In December 2019, COVID-19, a novel strain of coronavirus, was first reported in Wuhan, China and has since become a global pandemic. The virus continues to spread globally, has been declared a pandemic by the World Health Organization and has spread to over 100 countries, including the United States. The impact of this pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. The Company has experienced temporary closures of its offices in light of state and local orders and most of its employees continue to work remotely. In addition, the Company’s employees have not been able to conduct normal business travel, in particular as part of business development activities or in-person monitoring of clinical trial sites. Potential further impacts to the Company’s business include, but are not limited to, additional closures of its facilities or those of its vendors, continued disruptions or restrictions on its employees’ ability to travel, disruptions to or delays in ongoing clinical trials, third-party manufacturing supply and other operations, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the U.S. Food and Drug Administration or other regulatory authorities, and the Company’s ability to raise capital and conduct business development activities. Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (GAAP). The preparation of the Company’s condensed consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenue, and expenses. The most significant estimates in the Company’s financial statements relate to revenue recognition and expenses incurred for clinical trials. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Cash and Cash Equivalents Cash and cash equivalents consist of cash and highly liquid investments with original maturities of three months or less at the date of purchase. The carrying amounts approximate fair value due to the short maturities of these investments. Cash and cash equivalents include cash in readily available checking and money market funds. Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Revenue Recognition To date, substantially all of the Company’s revenue has been derived from its prior license agreements with Santen Pharmaceuticals Co. Ltd. (Santen) and Ambrx, Inc. (Ambrx) as described in Note 6. The terms of these arrangements included payments to the Company for the following: non-refundable, up-front license fees; development, regulatory and commercial milestone payments; payments for manufacturing supply services the Company provides through its contract manufacturers; and royalties on net sales of licensed products. In accordance with ASU 2014-09, the Company performs the following five steps in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of these agreements: (i) identification of the contract(s) with a customer; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when, or as, the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services transferred to the customer. Once a contract is determined to be within the scope of Accounting Standards Codification 606, Revenue from Contracts with Customers As part of the accounting for these arrangements, the Company develops assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price, which may include development timelines, reimbursement rates for personnel costs, discount rates, and probabilities of technical and regulatory success. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promised goods or services, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of each arrangement that includes development, commercialization, and regulatory milestone payments, the Company evaluates whether the achievement of the milestones is considered probable and estimates the amount to be included in the transaction price using the most likely amount method. Performance milestone payments represent a form of variable consideration. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Achievement of milestones that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable until the approvals are achieved. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis and the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Manufacturing Supply Services: Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations at the outset of the arrangement. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its out-licensing arrangements. The Company receives payments from its collaborators based on billing schedules established in each contract. Up-front and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under its collaboration arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less. Clinical Trial Expense Accruals As part of the process of preparing the Company’s financial statements, the Company is required to estimate expenses resulting from its obligations under contracts with vendors, clinical sites, contract research organizations (CROs), and consultants in connection with conducting clinical trials. The financial terms of these contracts vary and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by recording those expenses in the period in which services are performed and efforts are expended. The Company accounts for these expenses according to the progress of the clinical trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through discussion with the clinical sites and applicable personnel and outside service providers as to the progress or state of consummation of trials. During the course of a clinical trial, the Company adjusts the clinical expense recognition if actual results differ from its estimates. The Company makes estimates of accrued expenses as of each balance sheet date based on the facts and circumstances known at that time. The Company’s clinical trial accruals are dependent upon accurate reporting by clinical sites, CROs, and other third-party vendors. Although the Company does not expect its estimates to differ materially from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low for any particular period. For the six months ended June 30, 2020 and 2019, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials. Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Net loss and comprehensive loss were the same for all periods presented. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average shares of common stock outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted average number of common shares outstanding that are subject to repurchase. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock method. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares): June 30, 2020 2019 Warrants to purchase common stock 1,561,903 1,561,903 Common stock options and restricted stock units 658,404 436,845 ESPP shares 809 383 2,221,116 1,999,131

Short-Term Investments, Cash Eq

Short-Term Investments, Cash Equivalents and Fair Value Measurements	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Short-Term Investments, Cash Equivalents and Fair Value Measurements	2. Short-Term Investments, Cash Equivalents and Fair Value Measurements The Company classifies all investments as available-for-sale securities, as the sale of such investments may be required prior to maturity to implement management strategies. These investments are carried at amortized cost which approximates fair value. A decline in the market value of any short-term investment below cost that is determined to be other-than-temporary will result in a revaluation of its carrying amount to fair value. The impairment is charged to earnings and a new cost basis for the security is established. At June 30, 2020 and December 31, 2019, the Company had no short-term investments and no such impairment charges were recorded for any period presented. Realized gains and losses from the sale of short-term investments, if any, are determined on a specific identification basis. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense on the consolidated statements of operations. Realized and unrealized gains and losses during the periods presented were immaterial. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the straight-line method and are included in interest income on the consolidated statements of operations. Interest and dividends on securities classified as available-for-sale are included in interest income on the consolidated statements of operations. The carrying amounts of cash and cash equivalents, prepaid and other assets, accounts payable and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Based on the borrowing rates currently available to the Company for loans with similar terms, which is considered a Level 2 input, the Company believes that the fair value of long-term debt approximates its carrying value. The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Long-Term Debt	3 . Long-Term Debt Long-term debt and unamortized debt discount balances were as follows (in thousands): June 30, December 31, 2020 2019 Long-term debt $ 4,667 $ 5,600 Less debt discount, net of current portion (39 ) (61 ) Long-term debt, net of debt discount 4,628 5,539 Less current portion of long-term debt (1,867 ) (2,800 ) Long-term debt, net of current portion $ 2,761 $ 2,739 Current portion of long-term debt $ 1,867 $ 2,800 Current portion of debt discount (121 ) (196 ) Current portion of long-term debt, net $ 1,746 $ 2,604 In May 2018, the Company entered into a third amendment to its Amended and Restated Loan and Security Agreement with Silicon Valley Bank (the 2018 Amended SVB Loan) under which the Company borrowed $7.0 million, all of which was immediately used to repay the Company’s existing loan with SVB (the 2017 Amended SVB Loan). In accordance with the terms of the 2017 Amended SVB Loan, the Company paid a final payment of $0.3 million associated with the payoff of the 2017 Amended SVB Loan. The transaction was accounted for as a debt modification. The 2018 Amended SVB Loan provides for interest to be paid at a rate of 9.0 30 months 6 months At maturity (or earlier prepayment), the Company is required to make a final payment equal to 4.0% 1.0% The 2018 Amended SVB Loan is collateralized by substantially all of the Company’s assets, other than the Company’s intellectual property, and contains customary conditions of borrowing, events of default and covenants, including covenants that restrict the Company’s ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of the Company’s capital stock. Should an event of default occur, including the occurrence of a material adverse change, the Company could be liable for immediate repayment of all obligations under the 2018 Amended SVB Loan. As of June 30, 2020, In connection with the 2018 Amended SVB Loan, the Company issued SVB a warrant to purchase 5,363 shares of its common stock at an exercise price of $26.10 per share. The warrant is fully exercisable and expires on May 3, 2025. The fair value of the warrant and the final payment related to the 2018 Amended SVB Loan were recorded as debt discounts and are being amortized to interest expense using the effective interest method over the term of the debt, in addition to the remaining unamortized discounts related to the 2017 Amended SVB Loan. At June 30, 2020, the Company had the following exercisable outstanding warrants for the purchase of common stock issued in connection with the Company’s loan agreements with SVB: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 $ 77.40 January 25, 2024 4,669 $ 51.40 May 3, 2025 5,363 $ 26.10 15,747 Future minimum principal and interest payments under the 2018 Amended SVB Loan, including the final payment after execution of the Deferral Agreement in April 2020, are as follows (in thousands): Remaining 2020 $ 678 2021 3,066 2022 1,717 5,461 Less interest and final payment (794 ) Long-term debt $ 4,667

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	4 . Commitments and Contingencies License Agreements The Company has entered into various license agreements pursuant to which the Company acquired licenses to certain intellectual property. The agreements generally required an upfront license fee and, in some cases, reimbursement of patent costs. Additionally, under each agreement, the Company may be required to pay annual maintenance fees, royalties, milestone payments and sublicensing fees. Each of the license agreements is generally cancelable by the Company, given appropriate prior written notice. At June 30, 2020, potential future milestone payments under these agreements, including future milestone payments associated with TRC253 acquired from Janssen Pharmaceutica N.V. (Janssen) as discussed in Note 6, totaled an aggregate of approximately $66.0 million.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2020
Stockholders Equity Note [Abstract]
Stockholders' Equity	5. Stockholders’ Equity Sales of Common Stock In October 2019, as amended in April 2020, the Company entered into a Common Stock Purchase Agreement (the 2019 Purchase Agreement) with Aspire Capital which provides that, upon the terms and subject to the conditions and limitations set forth in the 2019 Purchase Agreement, Aspire Capital is committed to purchase up to an aggregate of $15.0 million of shares of the Company’s common stock solely at the Company’s request from time to time during a 30 month period and at prices based on the market price at the time of each sale. In consideration for entering into the 2019 Purchase Agreement and concurrently with the execution of the 2019 Purchase Agreement, the Company issued 142,658 shares of its common stock to Aspire Capital. As of June 30, 2020 and the date of this report, the Company had sold an aggregate 1.5 million and 2.9 million, respectively, shares of common stock under the 2019 Purchase Agreement with Aspire Capital for gross proceeds of $3.3 million and $5.9 million, respectively. At-The-Market Issuance Sales Agreement In September 2018, as amended in February 2019, the Company entered into the Sales Agreement with JonesTrading, pursuant to which it may sell from time to time, at its option, up to an aggregate of $11.6 million of the Company’s shares of its common stock through JonesTrading, as sales agent, subject to limitations on the amount of securities the Company may sell under its effective registration statement on Form S-3 within any 12 month period. The Company is required to pay JonesTrading 2.5% of gross proceeds for the common stock sold through the Sales Agreement. As of June 30, 2020, the Company had sold an aggregate 3.0 million shares of common stock through the Sales Agreement with JonesTrading for gross proceeds of $7.3 million and $4.2 million of common stock remained available for sale under the Sales Agreement. Equity Plan Activity During the three and six months ended June 30, 2020, t he Company issued shares of common stock upon the exercise of outstanding stock options. he Company issued no and 2,078 shares of common stock, respectively, upon the vesting of restricted stock units. The Company withheld 1,442 shares of common stock on the vesting date of certain restricted stock units to settle the employees’ minimum statutory tax obligations for income and other related employment taxes, the payment of which is reported as a financing activity in the unaudited condensed consolidated statement of cash flows for the six months ended June 30, 2020. the Company issued 2,450 shares of common stock in connection with the employee stock purchase plan. During the year ended December 31, 2019, the Company issued no shares of common stock upon the exercise of outstanding stock options, 2,738 shares of common stock upon the vesting of restricted stock units, and 6,535 shares of common stock in connection with the employee stock purchase plan. Common Stock Warrants As of June 30, 2020 , the Company had the following outstanding warrants for the purchase of common stock: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 77.40 January 25, 2024 4,669 51.40 March 27, 2024 1,369,602 27.00 March 27, 2025 176,554 0.10 May 3, 2025 5,363 26.10 1,561,903 During the three and six months ended June 30, 2020 and the year ended December 31, 2019, no warrants were exercised. Stock-Based Compensation Expense The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Three Months Ended Six Months Ended June 30, June 30, 2020 2019 2020 2019 Risk-free interest rate 0.4 % 1.9 % 1.2 % 2.6 % Expected volatility 88 % 87 % 86 % 81 % Expected term (in years) 5.8 5.5 6.2 6.2 Expected dividend yield — % — % — % — % Stock compensation expense for the employee stock purchase plan was immaterial for the three and six months ended June 30, 2020 and 2019. The allocation of stock-based compensation expense was as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2020 2019 2020 2019 Research and development $ 105 $ 205 $ 212 $ 521 General and administrative 158 211 318 491 $ 263 $ 416 $ 530 $ 1,012

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2020
Collaborations Disclosure [Abstract]
Collaborations	6. Collaborations 3D Medicines and Alphamab In December 2019, the Company, 3D Medicines Co., Ltd. (3D Medicines), and Jiangsu Alphamab Biopharmaceuticals Co., Ltd. (Alphamab) entered into the Envafolimab Collaboration Agreement for the development of envafolimab, also known as KN035, an investigational PD-L1 sdAb, or nanobody, administered by subcutaneous injection, for the treatment of soft tissue sarcoma in North America. No consideration was exchanged in the Envafolimab Collaboration Agreement. Given no consideration was exchanged, no value was assigned to the Envafolimab Collaboration Agreement in the accompanying condensed consolidated balance sheet. Pursuant to the Envafolimab Collaboration Agreement, the Company was granted an exclusive license to develop and commercialize envafolimab for the treatment of sarcoma in North America. The Company is responsible for conducting, and will bear the costs of Phase 1, Phase 2, and Phase 3 or post-approval clinical trials in North America for envafolimab in the indications of refractory and first line treatment of soft tissue sarcoma. 3D Medicines and Alphamab are responsible for conducting, and will bear the costs of, investigational new drug (IND)-enabling studies (other than those specific to the sarcoma indication) and the preparation of chemistry, manufacturing and controls (CMC) activities sections of an IND application for envafolimab. 3D Medicines and Alphamab have agreed to manufacture and supply, or to arrange for a third party manufacturer to manufacture and supply, envafolimab to the Company at pre-negotiated prices that vary based on clinical or commercial use. 3D Medicines and Alphamab retained the right to develop envafolimab in all territories outside of North America as well as within North America for all indications other than soft tissue sarcoma. The Company will be responsible for commercializing envafolimab for sarcoma in North America, including booking of sales revenue, unless (a) envafolimab is first approved in North America for an indication other than soft tissue sarcoma and launched in North America, or (b) envafolimab is first approved in North America for soft tissue sarcoma and subsequently approved in North America for an additional non-orphan indication and sold commercially by 3D Medicines and/or Alphamab, in which case 3D Medicines and Alphamab will be responsible for commercializing envafolimab for soft tissue sarcoma in North America, including booking of sales revenue. If 3D Medicines and Alphamab become responsible for commercialization under the Envafolimab Collaboration Agreement, the Company has the option to co-market envafolimab for sarcoma in North America. In the event that envafolimab is first approved in North America for sarcoma and within three years of the commercial launch of envafolimab in North America for sarcoma 3D Medicines and Alphamab replace the Company as the party responsible for commercialization, and the Company elects and 3D Medicines and Alphamab agree for the Company to not co-market envafolimab for sarcoma in North America, then 3D Medicine and Alphamab will be required to compensate the Company for its costs associated with preparing for and conducting commercial activities. If the Company has the responsibility for commercialization under the Envafolimab Collaboration Agreement, the Company will owe 3D Medicines and Alphamab tiered double digit royalties on net sales of envafolimab for sarcoma in North America ranging from the teens to mid-double digits. If 3D Medicines and Alphamab have responsibility for commercialization under the Envafolimab Collaboration Agreement, the Company will be entitled to (a) escalating double digit royalties on net sales of envafolimab for sarcoma in North America ranging from the teens to mid-double digits if the Company has chosen to not co-market envafolimab in sarcoma or (b) a 50% royalty on net sales of envafolimab for sarcoma in North America if the Company has chosen to co-market envafolimab in sarcoma. Payment obligations under the Envafolimab Collaboration Agreement continue on a country-by-country basis until the last to expire licensed patent covering envafolimab expires. 3D Medicines and Alphamab retain the right to reacquire the rights to envafolimab for sarcoma in North America in connection with an arm’s length sale to a third party, provided that the sale may not occur prior to completion of a pivotal trial of envafolimab in sarcoma without the Company’s written consent and the parties must negotiate in good faith and agree to fair compensation to be paid to the Company for the value of and opportunity represented by the required rights. Each party agreed that during the term of the Envafolimab Collaboration Agreement, it would not develop or license from any third party a monospecific inhibitor to PD-L1 or PD-1. The term of the Envafolimab Collaboration Agreement continues until the later of the date the parties cease further development and commercialization of envafolimab for sarcoma in North America or the expiration of all payment obligations. The Envafolimab Collaboration Agreement may be terminated earlier by a party in the event of an uncured material breach by the other party or bankruptcy of the other party, or for safety reasons related to envafolimab. In the event the Company elects, or a joint steering committee determines, to cease further development or commercialization of envafolimab, or if the Company fails to use commercially reasonable efforts to develop (including progress in clinical trials) and commercialize envafolimab and does not cure such failure within a specified time period, then the Company’s rights and obligations under the Envafolimab Collaboration Agreement will revert to 3D Medicines and Alphamab. I-Mab In November 2018, the Company and I-Mab Biopharma (I-Mab) entered into separate strategic collaboration and clinical trial agreements (the Collaboration Agreements) for the development of programs for multiple immuno-oncology product candidates, including I-Mab’s proprietary CD73 antibody TJ004309 (the TJ004309 Agreement) as well as up to five proprietary bispecific antibodies currently under development by I-Mab (the Bispecific Agreement). No consideration was exchanged in the Collaboration Agreements. Given the early preclinical stage of development of these assets as of the agreement date, no value was assigned to the Collaboration Agreements in the accompanying consolidated balance sheets. TJ004309 Agreement Pursuant to the TJ004309 Agreement, the Company and I-Mab will collaborate on developing the TJ004309 antibody, with the Company bearing the costs of filing an IND and for Phase 1 clinical trials, with the parties sharing costs equally for Phase 2 clinical trials, and with the Company and I-Mab bearing 40% and 60%, respectively, of the costs for pivotal clinical trials. I-Mab will be responsible for the cost of certain non-clinical activities, the drug supply of TJ004309, and any reference drugs used in the clinical trials. Each of the parties also agreed for a specified period of time to not develop or license to or from a third party any monoclonal antibody targeting CD73 or any other biologic for certain indications that a joint steering committee (JSC), as set up under the TJ004309 Agreement, selects for TJ004309 development. In the event that I-Mab out-licenses the rights to TJ004309 to a third party, the Company would be entitled to receive escalating portions of royalty and non-royalty consideration received by I-Mab with respect to certain territories outside of Greater China. In the event that I-Mab commercializes TJ004309, the Company would be entitled to receive a royalty percentage on net sales by I-Mab in North America ranging from the mid-single digits to low double digits, and in the EU and Japan in the mid-single digits. The portions of certain third party royalty and non-royalty consideration and the royalty from net sales by I-Mab to which the Company would be entitled will escalate based on the phase of development and relevant clinical trial obligations the Company completes under the TJ004309 Agreement, ranging from a high-single digit to a mid-teen percentage of non-royalty consideration as well as a double digit percentage of royalty consideration. In March 2020 , I-Mab issued a press release announcing a strategic partnership with Kalbe Genexine Biologics (KG Bio), whereby KG Bio received what the press release described as a right of first negotiation outside North America for TJ004309 for up to The TJ004309 TJ004309 TJ004309 TJ004309 Bispecific Agreement Pursuant to the Bispecific Agreement, the Company and I-Mab may mutually select through a JSC up to five of I-Mab’s bispecific antibody product candidates within a five-year period for development and commercialization in North America. For each product candidate selected by the JSC for development under the Bispecific Agreement, I-Mab will be responsible and bear the costs for IND-enabling studies and establishing manufacturing for the product candidate, while the Company will be responsible for and bear the costs of filing an IND and conducting Phase 1 and Phase 2 clinical trials, and the Company will be responsible for and will share equally with I-Mab in the costs of conducting Phase 3 or pivotal clinical trials, in each case within North America. Subject to I-Mab’s right to co-promote an approved product candidate, the Company will be responsible for commercializing any approved product candidates in North America and will share profits and losses equally with I-Mab in North America. The Company would also be entitled to tiered low single digit royalties on net sales of product candidates in the EU and Japan. At any time prior to completing the first pivotal clinical study for a product candidate or if I-Mab ceases to support development costs or pay its portion of Phase 3 clinical trial costs for a product candidate or the JSC decides to cease development over the Company’s objections after initiating Phase 3 clinical trials, the Company will have an option to obtain an exclusive license to such product candidate in all territories except Greater China and Korea, and any other territories in which I-Mab previously licensed rights to a third party subject to the Company’s right of first refusal for any licenses I-Mab may grant to third-parties. If the Company exercises the option, it would assume sole responsibility for developing and commercializing the product candidate in the licensed territory, and in lieu of profit or loss sharing with I-Mab with respect to such product candidate, the Company would owe I-Mab pre-specified upfront and milestone payments and royalties on net sales, with the payments and royalties escalating depending on the phase of development the product candidate reached at the time the Company obtained the exclusive license as follows: (i) if before IND-enabling studies and the preparation of the CMC activities of the collaborative product, the Company would owe I-Mab a one-time upfront payment of $10.0 million, development and regulatory based milestone payments totaling up to $90.0 million that begin upon completion of a pivotal study, sales milestones totaling up to $250.0 million, and royalties in the mid-single digits on annual net sales; (ii) if after IND submission but before completion of a Phase 1a clinical trial of the collaborative product, the Company would owe I-Mab a one-time upfront payment of $25.0 million, development and regulatory based milestone payments totaling up to $125.0 million that begin upon completion of a pivotal study, sales milestones totaling up to $250.0 million, and royalties in the high single digits on annual net sales; (iii) if after completion of a Phase 1a clinical trial but before completion of Phase 2 proof of concept clinical trial for the collaborative product, the Company would owe I-Mab a one-time upfront payment of $50.0 million, development and regulatory based milestone payments totaling up to $250.0 million that begin upon completion of a pivotal study, sales milestones totaling up to $250.0 million, and royalties in the low double digits on annual net sales; and (iv) if after completion of Phase 2 proof of concept clinical trial and before completion of pivotal study for the collaborative product, the Company would owe I-Mab a one-time upfront payment of $80.0 million, development and regulatory based milestone payments totaling up to $420.0 million that begin upon completion of a pivotal study, sales milestones totaling up to $250.0 million, and royalties in the high-teen double digits on annual net sales. Each party agreed that for a specified period of time, it would not develop or license to or from any third party any bispecific monoclonal antibody targeting the same two biological targets as those of any selected product candidates under the Bispecific Agreement. If development of any selected product candidates is terminated by a decision of the JSC, all rights to the product candidate will revert to I-Mab, subject to the Company’s right to obtain an exclusive license in certain circumstances. If development is terminated after submission of an IND and prior to initiating Phase 3 clinical trials or after initiating Phase 3 clinical trials and with the Company’s concurrence, the Company would be entitled to tiered low single digit royalties on net sales of the product candidate in North America, the EU, and Japan. The Bispecific Agreement may be terminated by either party in the event of an uncured material breach by the other party, bankruptcy of the other party, or with respect to any selected product candidate, for safety reasons related to that product candidate. In March 2020, the Company learned that I-Mab entered into two license and collaboration agreements with ABL Bio in July 2018 (ABL Bio License 1 and ABL Bio License 2). Under ABL Bio License 1, I-Mab granted to ABL Bio exclusive, worldwide (excluding Greater China), royalty-bearing rights to develop and commercialize a bispecific antibody (the BsAb) using certain monoclonal antibody sequences. Under ABL License 2, I-Mab and ABL agreed to collaborate to develop three PD-L1-based bispecific antibodies by using ABL Bio’s proprietary bispecific antibody technology and commercialize them in their respective territories, which, collectively, include China, Hong Kong, Macau, Taiwan and South Korea, and other territories throughout the rest of the world if both parties agree to do so in such other territories during the performance of the agreement. On April 8, 2020, the Company issued a notice of dispute regarding possible breach of the Bispecific Agreement related to I-Mab entering into ABL License 1 and ABL License 2. The Company cannot currently estimate the likely outcome of the dispute under the Bispecific Agreement. Santen In March 2014, the Company entered into a license agreement with Santen, under which the Company granted Santen an exclusive, worldwide license to certain patents, information and know-how related to carotuximab. Under the agreement, Santen was permitted to use, develop, manufacture and commercialize carotuximab products for ophthalmology indications, excluding systemic treatment of ocular tumors. Santen also had the right to grant sublicenses to affiliates and third party collaborators. In the event Santen sublicensed any of its rights under the agreement, Santen would have been obligated to pay the Company a portion of any upfront and certain milestone payments received under such sublicense. Santen had sole responsibility for funding, developing, seeking regulatory approval for and commercializing carotuximab products in the field of ophthalmology. In the event that Santen failed to meet certain commercial diligence obligations, the Company would have had the option to co-promote carotuximab products in the field of ophthalmology in the United States with Santen. If the Company exercised this option, the Company would have been obligated to pay Santen a percentage of certain development expenses, and the Company would have received a percentage of profits from sales of the licensed products in the ophthalmology field in the United States, but would not also receive royalties on such sales. In consideration of the rights granted to Santen under the agreement, the Company received a one-time upfront fee of $10.0 million. In addition, the Company was eligible to receive up to a total of $155.0 million in milestone payments upon the achievement of certain milestones, of which $20.0 million related to the initiation of certain development activities, $52.5 million related to the submission of certain regulatory filings and receipt of certain regulatory approvals and $82.5 million related to commercialization activities and the achievement of specified levels of product sales. As of June 30, 2020 and December 31, 2019, two development milestones had been received totaling $10.0 million. If carotuximab products were successfully commercialized in the field of ophthalmology, Santen would have been required to pay the Company tiered royalties on net sales ranging from high single digits to low teens, depending on the volume of sales, subject to adjustments in certain circumstances. In addition, Santen would be required to reimburse the Company for all royalties due by the Company under certain third party agreements with respect to the use, manufacture or commercialization of carotuximab products in the field of ophthalmology by Santen and its affiliates and sublicensees. Royalties would have continued on a country-by-country basis through the later of the expiration of the Company’s patent rights applicable to the carotuximab products in a given country or 12 years after the first commercial sale of the first carotuximab product commercially launched in such country. The Company assessed this agreement and identified multiple promised goods and services, which include at inception: (1) a license to patents, information and know-how related to carotuximab, (2) a technology transfer, and (3) a collaboration, including technical and regulatory support provided by the Company. In addition, customer options were identified that include manufacturing and supply obligations and shared chemistry, manufacturing and controls (CMC) development activities. All performance obligations were satisfied by the year ended December 31, 2017, which completed the Company’s obligations. As of June 30, 2020, the transaction price included the $10.0 million upfront payment and the two development milestones received totaling $10.0 million, all of which had been fully recognized as revenue at December 31, 2017. The remaining $62.5 million of potential development and regulatory milestone payments were fully constrained as the achievement of the milestones was not considered probable, and therefore no amounts have been included in the transaction price for these remaining milestones. In addition, in accordance with ASU 2014-09, any consideration related to the commercialization and sales-based milestones (including royalties) will be recognized when the related sales occur and have also been excluded from the transaction price. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. No evenue was recognized related to this agreement for the three and six months ended June 30, 2020 and 2019. In March 2020, Santen announced the discontinuation of development of DE-122, and in June 2020 terminated the agreement. No further revenue will be recognized in connection with this agreement as Santen has terminated the DE-122 program. Janssen In September 2016, the Company entered into a license and option agreement with Janssen (the License and Option Agreement) under which Janssen granted the Company a license to technology and intellectual property to develop, manufacture and commercialize two compounds: a small molecule inhibitor of androgen receptor and androgen receptor mutations (the AR Mutant Program or TRC253) which is intended for the treatment of men with prostate cancer, and an inhibitor of NF-kB inducing kinase (the NIK Program or TRC694). Following completion of the pre-clinical development of TRC694, the Company determined the compound did not warrant further development and, in February 2019, issued written notice to terminate the License and Option Agreement with respect to the NIK Program and returned TRC694 and all rights thereto to Janssen. With respect to the AR Mutant Program, the License and Option Agreement, as amended, provided Janssen with an option, which was exercisable until 90 days after the Company demonstrated clinical proof of concept of TRC253, to regain the rights to the licensed intellectual property and to obtain an exclusive license to commercialize the compounds and certain other specified intellectual property developed under the AR Mutant Program. In April 2020, Janssen notified the Company that it would not regain the rights to TRC253, and therefore the Company now retains worldwide development and commercialization rights to the AR Mutant Program, and is obligated to pay to Janssen (x) development and regulatory based milestone payments totaling up to $45.0 million upon achievement of specified events, and (y) royalties in the low single digits based on annual net sales of AR Mutant Program products, subject to certain specified reductions. No consideration was exchanged for these assets on the acquisition date. Given the early preclinical stage of development of these assets and the low likelihood of success of development through regulatory approval on the acquisition date, no value was assigned to these assets in the accompanying consolidated balance sheet. The Company is obligated to use diligent efforts to develop the AR Mutant Program according to agreed upon development plans, timelines and budgets. The Company is further obligated as it relates to the AR Mutant Program to use commercially reasonable efforts to develop, obtain marketing approval for, and commercialize licensed products. Until the expiration or earlier termination of the development term of the AR Mutant Program, under the License and Option Agreement, subject to specified exceptions, the Company has agreed not to research, develop or commercialize any compounds or products related to the AR Mutant Program, other than pursuant to the collaboration with Janssen. The License and Option Agreement may be terminated for uncured breach, bankruptcy, or the failure or inability to demonstrate clinical proof of concept with respect to a particular program during specified timeframes. In addition, the License and Option Agreement will automatically terminate upon the expiration of all payment obligations of the Company to Janssen with respect of the AR Mutant Program. The Company may also terminate the License and Option Agreement in its entirety without cause, subject to specified conditions.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Organization And Accounting Policies [Abstract]
Organization and Business	Organization and Business TRACON Pharmaceuticals, Inc. (formerly Lexington Pharmaceuticals, Inc.) (TRACON or the Company) was incorporated in the state of Delaware on October 28, 2004. TRACON is a clinical stage biopharmaceutical company focused on the development and commercialization of novel targeted therapeutics for cancer. The Company’s product development platform, which emphasizes capital efficiency, also provides to ex-U.S. companies a rapid and capital-efficient U.S. drug development solution that includes U.S. and European Union (EU) clinical development expertise and U.S. commercialization expertise. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, TRACON Pharma Limited and TRACON Pharma International Limited, which were formed in September 2015 and January 2019, respectively, and are currently inactive. All significant intercompany accounts and transactions have been eliminated.
Basis of Presentation	Basis of Presentation As of June 30, 2020, the Company has devoted substantially all of its efforts to product development, raising capital, and building infrastructure and has not realized revenues from its planned principal operations. The Company has incurred operating losses since inception. As of June 30, 2020, the Company had an accumulated deficit of $170.8 million. The Company anticipates that it will continue to incur net losses into the foreseeable future as it continues the development and commercialization of its product candidates and works to develop additional product candidates through research and development programs. At June 30, 2020, the Company had cash and cash equivalents of $14.5 million. Based on the Company’s current business plan, management believes that there is substantial doubt as to whether existing cash and cash equivalents will be sufficient to meet its obligations as they become due within one year from the date these financial statements are issued. The Company’s ability to execute its operating plan through the second quarter of 2021 and beyond depends on its ability to obtain additional funding through equity offerings, debt financings, or potential licensing and collaboration arrangements. The accompanying unaudited condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business. However, the Company’s current working capital, anticipated operating expenses and net losses, and the uncertainties surrounding its ability to raise additional capital as needed, as discussed below, raise substantial doubt about its ability to continue as a going concern for a period of one year following the date that these financial statements are issued. The unaudited condensed consolidated financial statements do not include any adjustments for the recovery and classification of assets or the amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. The Company plans to continue to fund its losses from operations through its existing cash and cash equivalents, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements. In addition, the Company may fund its losses from operations through the common stock purchase agreement the Company entered into with Aspire Capital Fund, LLC (Aspire Capital) in October 2019, as amended in April 2020, for the purchase of up to $15.0 million of the Company’s common stock over the 30 month period of the purchase agreement, $11.7 million of which remained available for sale as of June 30, 2020 and/or the Capital on Demand TM Unaudited Interim Financial Information The unaudited condensed consolidated financial statements as of June 30, 2020, and for the three and six months ended June 30, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC), and with accounting principles generally accepted in the United States (GAAP) applicable to interim financial statements. These unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019, included in its Annual Report on Form 10-K filed with the SEC on February 28, 2020.
Reverse Stock Split	Reverse Stock Split On November 7, 2019, the Company filed an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-10 reverse stock split of its common stock (the reverse stock split). The reverse stock split applied to all of the Company’s outstanding shares of common stock and therefore did not affect any stockholder’s relative ownership percentage. In connection with the reverse stock split, the number of authorized shares of common stock was reduced from 200,000,000 shares to 20,000,000 shares. The number of authorized shares of preferred stock remained (and remains) unchanged at 10,000,000 shares. The par value of the common stock was not adjusted as a result of the reverse stock split. All of the Company’s stock options, warrants and restricted stock units outstanding immediately prior to the reverse stock split were proportionately adjusted. All share and price per share data for all periods presented in these consolidated financial statements and notes thereto have been adjusted to give effect to the reverse stock split, including retrospectively where applicable.
Risks and Uncertainties	Risks and Uncertainties In December 2019, COVID-19, a novel strain of coronavirus, was first reported in Wuhan, China and has since become a global pandemic. The virus continues to spread globally, has been declared a pandemic by the World Health Organization and has spread to over 100 countries, including the United States. The impact of this pandemic has been and will likely continue to be extensive in many aspects of society, which has resulted in and will likely continue to result in significant disruptions to the global economy, as well as businesses and capital markets around the world. The Company has experienced temporary closures of its offices in light of state and local orders and most of its employees continue to work remotely. In addition, the Company’s employees have not been able to conduct normal business travel, in particular as part of business development activities or in-person monitoring of clinical trial sites. Potential further impacts to the Company’s business include, but are not limited to, additional closures of its facilities or those of its vendors, continued disruptions or restrictions on its employees’ ability to travel, disruptions to or delays in ongoing clinical trials, third-party manufacturing supply and other operations, the potential diversion of healthcare resources away from the conduct of clinical trials to focus on pandemic concerns, interruptions or delays in the operations of the U.S. Food and Drug Administration or other regulatory authorities, and the Company’s ability to raise capital and conduct business development activities.
Use of Estimates	Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (GAAP). The preparation of the Company’s condensed consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenue, and expenses. The most significant estimates in the Company’s financial statements relate to revenue recognition and expenses incurred for clinical trials. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash and highly liquid investments with original maturities of three months or less at the date of purchase. The carrying amounts approximate fair value due to the short maturities of these investments. Cash and cash equivalents include cash in readily available checking and money market funds.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
Revenue Recognition	Revenue Recognition To date, substantially all of the Company’s revenue has been derived from its prior license agreements with Santen Pharmaceuticals Co. Ltd. (Santen) and Ambrx, Inc. (Ambrx) as described in Note 6. The terms of these arrangements included payments to the Company for the following: non-refundable, up-front license fees; development, regulatory and commercial milestone payments; payments for manufacturing supply services the Company provides through its contract manufacturers; and royalties on net sales of licensed products. In accordance with ASU 2014-09, the Company performs the following five steps in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of these agreements: (i) identification of the contract(s) with a customer; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when, or as, the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services transferred to the customer. Once a contract is determined to be within the scope of Accounting Standards Codification 606, Revenue from Contracts with Customers As part of the accounting for these arrangements, the Company develops assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price, which may include development timelines, reimbursement rates for personnel costs, discount rates, and probabilities of technical and regulatory success. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promised goods or services, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of each arrangement that includes development, commercialization, and regulatory milestone payments, the Company evaluates whether the achievement of the milestones is considered probable and estimates the amount to be included in the transaction price using the most likely amount method. Performance milestone payments represent a form of variable consideration. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Achievement of milestones that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable until the approvals are achieved. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis and the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Manufacturing Supply Services: Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations at the outset of the arrangement. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its out-licensing arrangements. The Company receives payments from its collaborators based on billing schedules established in each contract. Up-front and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under its collaboration arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.
Clinical Trial Expense Accruals	Clinical Trial Expense Accruals As part of the process of preparing the Company’s financial statements, the Company is required to estimate expenses resulting from its obligations under contracts with vendors, clinical sites, contract research organizations (CROs), and consultants in connection with conducting clinical trials. The financial terms of these contracts vary and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by recording those expenses in the period in which services are performed and efforts are expended. The Company accounts for these expenses according to the progress of the clinical trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through discussion with the clinical sites and applicable personnel and outside service providers as to the progress or state of consummation of trials. During the course of a clinical trial, the Company adjusts the clinical expense recognition if actual results differ from its estimates. The Company makes estimates of accrued expenses as of each balance sheet date based on the facts and circumstances known at that time. The Company’s clinical trial accruals are dependent upon accurate reporting by clinical sites, CROs, and other third-party vendors. Although the Company does not expect its estimates to differ materially from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low for any particular period. For the six months ended June 30, 2020 and 2019, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Net loss and comprehensive loss were the same for all periods presented.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average shares of common stock outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted average number of common shares outstanding that are subject to repurchase. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock method. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares): June 30, 2020 2019 Warrants to purchase common stock 1,561,903 1,561,903 Common stock options and restricted stock units 658,404 436,845 ESPP shares 809 383 2,221,116 1,999,131

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2020
Organization And Accounting Policies [Abstract]
Schedule of potentially dilutive securities not included in the calculation of diluted net loss per share	Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares): June 30, 2020 2019 Warrants to purchase common stock 1,561,903 1,561,903 Common stock options and restricted stock units 658,404 436,845 ESPP shares 809 383 2,221,116 1,999,131

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long-term debt and unamortized debt discount balances	Long-term debt and unamortized debt discount balances were as follows (in thousands): June 30, December 31, 2020 2019 Long-term debt $ 4,667 $ 5,600 Less debt discount, net of current portion (39 ) (61 ) Long-term debt, net of debt discount 4,628 5,539 Less current portion of long-term debt (1,867 ) (2,800 ) Long-term debt, net of current portion $ 2,761 $ 2,739 Current portion of long-term debt $ 1,867 $ 2,800 Current portion of debt discount (121 ) (196 ) Current portion of long-term debt, net $ 1,746 $ 2,604
Schedule of exercisable outstanding warrants for purchase of common stock issued	At June 30, 2020, the Company had the following exercisable outstanding warrants for the purchase of common stock issued in connection with the Company’s loan agreements with SVB: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 $ 77.40 January 25, 2024 4,669 $ 51.40 May 3, 2025 5,363 $ 26.10 15,747 As of June 30, 2020 , the Company had the following outstanding warrants for the purchase of common stock: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 77.40 January 25, 2024 4,669 51.40 March 27, 2024 1,369,602 27.00 March 27, 2025 176,554 0.10 May 3, 2025 5,363 26.10 1,561,903
Schedule of future minimum principal and interest payments	Future minimum principal and interest payments under the 2018 Amended SVB Loan, including the final payment after execution of the Deferral Agreement in April 2020, are as follows (in thousands): Remaining 2020 $ 678 2021 3,066 2022 1,717 5,461 Less interest and final payment (794 ) Long-term debt $ 4,667

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2020
Stockholders Equity Note [Abstract]
Schedule of exercisable outstanding warrants for purchase of common stock issued	At June 30, 2020, the Company had the following exercisable outstanding warrants for the purchase of common stock issued in connection with the Company’s loan agreements with SVB: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 $ 77.40 January 25, 2024 4,669 $ 51.40 May 3, 2025 5,363 $ 26.10 15,747 As of June 30, 2020 , the Company had the following outstanding warrants for the purchase of common stock: Expiration Number of shares Exercise price May 13, 2022 1,841 $ 108.60 November 14, 2023 through June 4, 2024 3,874 77.40 January 25, 2024 4,669 51.40 March 27, 2024 1,369,602 27.00 March 27, 2025 176,554 0.10 May 3, 2025 5,363 26.10 1,561,903
Summary of weighted-average assumptions used Black-Scholes option pricing model to determine the fair value	The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Three Months Ended Six Months Ended June 30, June 30, 2020 2019 2020 2019 Risk-free interest rate 0.4 % 1.9 % 1.2 % 2.6 % Expected volatility 88 % 87 % 86 % 81 % Expected term (in years) 5.8 5.5 6.2 6.2 Expected dividend yield — % — % — % — %
Summary of allocation of stock-based compensation expense	The allocation of stock-based compensation expense was as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2020 2019 2020 2019 Research and development $ 105 $ 205 $ 212 $ 521 General and administrative 158 211 318 491 $ 263 $ 416 $ 530 $ 1,012

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Nov. 07, 2019	Oct. 31, 2019	Jun. 30, 2020	Dec. 31, 2019	Feb. 28, 2019	Sep. 30, 2018
Basis of Presentation
Accumulated deficit			$ (170,806,000)	$ (162,334,000)
Cash and cash equivalents			$ 14,453,000	$ 16,412,000
Reverse split of Common Stock	1-for-10
Common Stock, Shares Authorized			20,000,000	20,000,000
Preferred Stock, Shares Authorized	10,000,000		10,000,000	10,000,000
Maximum
Basis of Presentation
Common Stock, Shares Authorized	200,000,000
Minimum
Basis of Presentation
Common Stock, Shares Authorized	20,000,000
Jones Trading Institutional Services LLC | Capital on Demand Sales Agreement | Common Stock
Basis of Presentation
Maximum aggregate value of stock to be sold					$ 11,600,000	$ 11,600,000
Remaining amount available under the Sales Agreement			$ 4,200,000
Aspire Capital | Common Stock
Basis of Presentation
Maximum aggregate value of common stock to be purchase		$ 15,000,000
Sale duration for common stock under purchase agreement		30 months
Remaining amount available under the purchase Agreement			$ 11,700,000

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in the Calculation of Diluted Net Loss Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive securities
Antidilutive securities	2,221,116	1,999,131
Warrants to Purchase Common Stock
Antidilutive securities
Antidilutive securities	1,561,903	1,561,903
Common Stock Options and Restricted Stock Units
Antidilutive securities
Antidilutive securities	658,404	436,845
ESPP Shares
Antidilutive securities
Antidilutive securities	809	383

Short-Term Investments, Cash _2

Short-Term Investments, Cash Equivalents and Fair Value Measurements - Additional Information (Details)	Jun. 30, 2020USD ($)
Fair Value Disclosures [Abstract]
Short-term investments	$ 0
Amount of transfers between levels	$ 0

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt and Unamortized Debt Discount Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Long-term debt
Long-term debt	$ 4,667	$ 5,600
Less debt discount, net of current portion	(39)	(61)
Long-term debt, net of debt discount	4,628	5,539
Less current portion of long-term debt	(1,867)	(2,800)
Long-term debt, net of current portion	2,761	2,739
Current portion of long-term debt	1,867	2,800
Current portion of debt discount	(121)	(196)
Current portion of long-term debt, net	$ 1,746	$ 2,604

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	1 Months Ended	6 Months Ended
	May 31, 2018	Jun. 30, 2020
Debt Instrument [Line Items]
Warrants issued		1,561,903
Silicon Valley Bank
Debt Instrument [Line Items]
Warrants issued		15,747
2018 SVB Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Proceeds from long-term debt	$ 7,000,000
Interest rate	9.00%
Repayment period	30 months
Additional fee on final payment due (as a percent)	4.00%
Warrants issued	5,363
Exercise price (per share)	$ 26.10
2018 SVB Loan | Silicon Valley Bank | After May 3, 2020
Debt Instrument [Line Items]
Prepayment fee (as a percent)	1.00%
2017 SVB Loan | Silicon Valley Bank
Debt Instrument [Line Items]
Final payment on payoff	$ 300,000
Deferral Agreement | Silicon Valley Bank
Debt Instrument [Line Items]
Extension of period for interest only payments		6 months
Maturity date		Jun. 30, 2022
Description of extension of period for interest only payments		In April 2020, the Company entered into a deferral agreement with SVB (the Deferral Agreement) for an interest-only payment period of 6 months, with a corresponding 6 month extension to the maturity date to June 2022.

Long-Term Debt - Schedule of Ex

Long-Term Debt - Schedule of Exercisable Outstanding Warrants for Purchase of Common Stock Issued (Details)	Jun. 30, 2020$ / sharesshares
Debt Instrument [Line Items]
Warrants issued	1,561,903
Silicon Valley Bank
Debt Instrument [Line Items]
Warrants issued	15,747
Silicon Valley Bank | May 13, 2022
Debt Instrument [Line Items]
Warrants issued	1,841
Exercise price (per share) | $ / shares	$ 108.60
Silicon Valley Bank | November 14, 2023 Through June 4, 2024
Debt Instrument [Line Items]
Warrants issued	3,874
Exercise price (per share) | $ / shares	$ 77.40
Silicon Valley Bank | January 25, 2024
Debt Instrument [Line Items]
Warrants issued	4,669
Exercise price (per share) | $ / shares	$ 51.40
Silicon Valley Bank | May 3, 2025
Debt Instrument [Line Items]
Warrants issued	5,363
Exercise price (per share) | $ / shares	$ 26.10

Long-Term Debt - Schedule of Fu

Long-Term Debt - Schedule of Future Minimum Principal and Interest Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 4,667	$ 5,600
2018 Amended SVB Loan
Debt Instrument [Line Items]
Remaining 2020	678
2021	3,066
2022	1,717
Long-term debt including final payment	5,461
Less interest and final payment	(794)
Long-term debt	$ 4,667

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	Jun. 30, 2020USD ($)
Research and development arrangement
Commitments and Contingencies
Potential milestone payable	$ 66

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Oct. 31, 2019	Sep. 30, 2018	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Feb. 28, 2019
Class Of Stock [Line Items]
Proceeds from sale of common stock					$ 8,122,000
Warrants exercised				0	0	0
Common Stock | Equity Plan Activity
Class Of Stock [Line Items]
Shares issued upon exercise of outstanding stock options				0	0	0
Shares issued in connection with employee stock purchase plan				2,450	2,450	6,535
Common Stock | Equity Plan Activity | Restricted Stock Units
Class Of Stock [Line Items]
Shares withheld on vesting date to settle employees minimum statutory tax obligations				1,442	1,442	0
Shares issued upon vesting of restricted stock units				0	2,078	2,738
Common Stock | Capital on Demand Sales Agreement | Jones Trading Institutional Services LLC
Class Of Stock [Line Items]
Stock issued during period, shares, new issues					3,000,000
Proceeds from sale of common stock					$ 7,300,000
Maximum aggregate value of stock to be sold			$ 11,600,000				$ 11,600,000
Percentage of gross proceeds, required to pay for common stock sold through sales agreement			2.50%
Common stock remains available for sale				$ 4,200,000	4,200,000
Aspire Capital | Common Stock
Class Of Stock [Line Items]
Maximum aggregate value of common stock to be purchase		$ 15,000,000
Sale duration for common stock under purchase agreement		30 months
Stock issued during period, shares, new issues		142,658
Stock issued during period, value, new issues	$ 1,500,000				2,900,000
Proceeds from sale of common stock	$ 3,300,000				$ 5,900,000

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Outstanding Warrants for Purchase of Common Stock Issued (Details)	Jun. 30, 2020$ / sharesshares
Class Of Stock [Line Items]
Warrants issued	1,561,903
May 13, 2022
Class Of Stock [Line Items]
Warrants issued	1,841
Exercise price (per share) | $ / shares	$ 108.60
November 14, 2023 Through June 4, 2024
Class Of Stock [Line Items]
Warrants issued	3,874
Exercise price (per share) | $ / shares	$ 77.40
January 25, 2024
Class Of Stock [Line Items]
Warrants issued	4,669
Exercise price (per share) | $ / shares	$ 51.40
March 27, 2024
Class Of Stock [Line Items]
Warrants issued	1,369,602
Exercise price (per share) | $ / shares	$ 27
March 27, 2025
Class Of Stock [Line Items]
Warrants issued	176,554
Exercise price (per share) | $ / shares	$ 0.10
May 3, 2025
Class Of Stock [Line Items]
Warrants issued	5,363
Exercise price (per share) | $ / shares	$ 26.10

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Weighted-Average Assumptions Fair Value of the Employee Stock Option Grants (Details) - Stock Option	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Class Of Stock [Line Items]
Risk-free interest rate	0.40%	1.90%	1.20%	2.60%
Expected volatility	88.00%	87.00%	86.00%	81.00%
Expected term (in years)	5 years 9 months 18 days	5 years 6 months	6 years 2 months 12 days	6 years 2 months 12 days

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Allocation of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Class Of Stock [Line Items]
Stock based compensation expense	$ 263	$ 416	$ 530	$ 1,012
Research and development
Class Of Stock [Line Items]
Stock based compensation expense	105	205	212	521
General and administrative
Class Of Stock [Line Items]
Stock based compensation expense	$ 158	$ 211	$ 318	$ 491

Collaborations - Additional Inf

Collaborations - Additional Information (Details)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Nov. 30, 2018USD ($)antibody	Mar. 31, 2014USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)Milestone	Jun. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2020USD ($)
Janssen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License and Option Agreement termination description					The License and Option Agreement may be terminated for uncured breach, bankruptcy, or the failure or inability to demonstrate clinical proof of concept with respect to a particular program during specified timeframes. In addition, the License and Option Agreement will automatically terminate upon the expiration of all payment obligations of the Company to Janssen with respect of the AR Mutant Program. The Company may also terminate the License and Option Agreement in its entirety without cause, subject to specified conditions.
Janssen | License and Option Agreement | AR Mutant Program
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development and regulatory based on milestone payments					$ 45,000,000
Exercisable period					90 days
Janssen | License and Option Agreement | NIK Program
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Consideration exchanged for assets acquired					$ 0
Value given to assets acquired			$ 0		$ 0
Bispecific Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty on net sales					50.00%
Bispecific Agreement | I-Mab
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maximum number of proprietary bispecific antibodies under development | antibody	5
Number of biological targets | antibody	2
Bispecific Agreement | I-Mab | North America
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maximum period of selecting candidates for development and commercialization	5 years
Bispecific Agreement | I-Mab | Before IND
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One time upfront payment fee	$ 10,000,000
Development and regulatory based on milestone payments	90,000,000
Potential milestones payments received	250,000,000
Bispecific Agreement | I-Mab | After IND Before Phase 1a
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One time upfront payment fee	25,000,000
Development and regulatory based on milestone payments	125,000,000
Potential milestones payments received	250,000,000
Bispecific Agreement | I-Mab | After Phase 1a and Before Phase 2
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One time upfront payment fee	50,000,000
Development and regulatory based on milestone payments	250,000,000
Potential milestones payments received	250,000,000
Bispecific Agreement | I-Mab | After Phase 2
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One time upfront payment fee	80,000,000
Development and regulatory based on milestone payments	420,000,000
Potential milestones payments received	$ 250,000,000
Collaboration Agreements | I-Mab
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Consideration exchanged for assets acquired					$ 0
Value given to assets acquired			0		$ 0
TJ4309 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of cost bearing	40.00%
TJ4309 Agreement | I-Mab
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of cost bearing	60.00%
Potential payments receivable									$ 340,000,000
Termination of agreement upon completion of clinical study	90 days
Additional payment	$ 35,000,000
TJ4309 Agreement | I-Mab | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-royalty consideration	35,000,000
TJ4309 Agreement | I-Mab | First Phase Clinical Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Termination fee	9,000,000
TJ4309 Agreement | I-Mab | First Phase Two Clinical Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Termination fee	$ 15,000,000
Collaborative Arrangement | Santen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One-time upfront fee		$ 10,000,000
Potential milestone that could be received		155,000,000
Royalty continuation term					12 years
Contracts Revenue			$ 0	$ 0	$ 0	$ 0
Type of Revenue [Extensible List]			tcon:CollaborationArrangementMember	tcon:CollaborationArrangementMember	tcon:CollaborationArrangementMember	tcon:CollaborationArrangementMember
Collaborative Arrangement | Santen | ASU 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments recognized as revenue					$ 0			$ 10,000,000
Collaborative Arrangement | Santen | Development Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone that could be received		20,000,000
Number of milestone payments received | Milestone					2
Potential milestones payments received					$ 10,000,000		$ 10,000,000
Collaborative Arrangement | Santen | Development Milestones | ASU 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments recognized as revenue								$ 10,000,000
Collaborative Arrangement | Santen | Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone that could be received		52,500,000
Collaborative Arrangement | Santen | Commercialization Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone that could be received		$ 82,500,000
Collaborative Arrangement | Santen | Development And Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance of potential milestone that could be received			$ 62,500,000		$ 62,500,000