TRACON Pharmaceuticals (TCON) 10-Q 8 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 03, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Tracon Pharmaceuticals, Inc.
Entity Central Index Key	1,394,319
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		29,840,844
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	TCON

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 34,434	$ 29,467
Short-term investments	18,933	4,999
Prepaid and other assets	1,494	1,591
Total current assets	54,861	36,057
Property and equipment, net	59	73
Total assets	54,920	36,130
Current liabilities:
Accounts payable and accrued expenses	10,511	6,800
Accrued compensation and related expenses	821	1,494
Current portion of deferred revenue		667
Long-term debt, current portion		2,837
Total current liabilities	11,332	11,798
Deferred revenue		2,333
Other long-term liabilities	372	409
Long-term debt, less current portion	6,258	4,603
Commitments and contingencies (Note 4)
Stockholders’ equity:
Preferred stock, $0.001 par value, authorized shares — 10,000,000 at June 30, 2018 and December 31, 2017; issued and outstanding shares—none
Common stock, $0.001 par value; authorized shares — 200,000,000 at June 30, 2018 and December 31, 2017; issued and outstanding shares — 29,829,598 and 17,711,928 at June 30, 2018 and December 31, 2017, respectively	30	18
Additional paid-in capital	159,747	121,670
Accumulated deficit	(122,819)	(104,701)
Total stockholders’ equity	36,958	16,987
Total liabilities and stockholders’ equity	$ 54,920	$ 36,130

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
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	200,000,000	200,000,000
Common stock, shares issued	29,829,598	17,711,928
Common stock, shares outstanding	29,829,598	17,711,928

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Collaboration revenue		$ 631	$ 3,000	$ 1,257
Type of Revenue [Extensible List]	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember
Operating expenses:
Research and development	$ 8,115	$ 4,893	$ 17,553	$ 10,475
General and administrative	1,622	2,068	3,373	4,032
Total operating expenses	9,737	6,961	20,926	14,507
Loss from operations	(9,737)	(6,330)	(17,926)	(13,250)
Other income (expense):
Interest expense, net	(23)	(233)	(192)	(458)
Other income (expense), net	6	(3)		(5)
Total other expense	(17)	(236)	(192)	(463)
Net loss	$ (9,754)	$ (6,566)	$ (18,118)	$ (13,713)
Net loss per share, basic and diluted	$ (0.33)	$ (0.40)	$ (0.76)	$ (0.84)
Weighted-average shares outstanding, basic and diluted	29,706,717	16,610,124	23,992,497	16,409,389

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (18,118)	$ (13,713)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,370	1,601
Common stock issued for services		23
Depreciation and amortization	14	34
Amortization of debt discount	51	56
Amortization of premium/discount on short-term investments	(11)	(4)
Noncash interest	146	180
Deferred rent	9	16
Deferred revenue	(3,000)	(873)
Changes in assets and liabilities:
Prepaid expenses and other assets	97	421
Accounts payable and accrued expenses	3,683	478
Accrued compensation and related expenses	(673)	(492)
Net cash used in operating activities	(16,432)	(12,273)
Cash flows from investing activities
Purchase of property and equipment		(24)
Purchases of available-for-sale short-term investments	(18,923)	(8,994)
Proceeds from the maturity of available-for-sale short-term investments	5,000	11,705
Net cash (used in) provided by investing activities	(13,923)	2,687
Cash flows from financing activities
Proceeds from long-term debt	7,000	8,000
Repayment of long-term debt	(8,320)	(8,850)
Proceeds from sale of common stock and warrants	38,674	1,000
Costs paid in connection with sales of common stock	(2,167)	(259)
Proceeds from issuance of common stock under equity plans	213	123
Payment of tax withholdings related to net share settlements of vested restricted stock awards	(78)	(137)
Net cash provided by (used in) financing activities	35,322	(123)
Increase (decrease) in cash and cash equivalents	4,967	(9,709)
Cash and cash equivalents at beginning of period	29,467	35,710
Cash and cash equivalents at end of period	$ 34,434	$ 26,001

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
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 and wet age-related macular degeneration. The Company’s lead product candidate is an antibody that binds to the endoglin receptor, which is essential to angiogenesis (the process of new blood vessel formation). The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, TRACON Pharma Limited, which was formed in September 2015 and is currently inactive. All significant intercompany accounts and transactions have been eliminated. Basis of Presentation As of June 30, 2018, 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, 2018, the Company had an accumulated deficit of $122.8 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, 2018, the Company had cash, cash equivalents and short-term investments of $53.4 million. Based on the Company’s current business plan, management believes that existing cash, cash equivalents and short-term investments will be sufficient to fund the Company’s obligations for at least 12 months after the release date of these condensed consolidated financial statements. The completion of the private placement of the Company’s common stock and warrants in March and April 2018, which generated net proceeds totaling $36.5 million, resolved the substantial doubt about the Company’s ability to continue as a going concern which existed at the reporting date of the December 31, 2017 consolidated financial statements. The Company plans to continue to fund its losses from operations through cash, cash equivalents and investments on hand, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements, including equity financing through the common stock purchase agreement the Company entered into with Aspire Capital Fund, LLC in March 2017 for the purchase of up to $21.0 million of the Company’s common stock over a 30-month period and/or the at-the-market equity offering sales agreement the Company entered into with Stifel, Nicolaus & Company, Incorporated in February 2016 for the sale of up to $25.0 million of the Company’s common stock, of which approximately $21.5 million remains available for sale 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 Even if the Company raises additional capital, it may also be required to modify, delay or abandon some of its plans which could have a material adverse effect on the Company’s business, operating results and financial condition and the Company’s ability to achieve its intended business objectives. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Unaudited Interim Financial Information The unaudited condensed consolidated financial statements at June 30, 2018, and for the three and six months ended June 30, 2018 and 2017, 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. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2017, included in its Annual Report on Form 10-K filed with the SEC on March 1, 2018. Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with 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 and the disclosure of contingent assets and liabilities in the Company’s financial statements and accompanying notes. The most significant estimates in the Company’s financial statements relate to revenue recognition, expenses incurred for clinical trials and the valuation of equity awards. 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, as well as U.S. treasury securities. 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 Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09) , which supersedes all existing revenue recognition requirements, . This new standard requires a company to recognize revenues when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. ASU 2014-09 was applied to all contracts on January 1, 2018, the date of adoption. did not identify any accounting changes that impacted the amount of historically reported retained earnings therefore no adjustment to retained earnings was required upon adoption. The following is the total revenue that would have been recorded in the three and six months ended June 30, 2018 under the superseded revenue recognition guidance, Accounting Standards Codification 605, Revenue Recognition (ASC 605) , had ASU 2014-09 not been adopted (in thousands): For the Three Months Ended June 30, 2018 For the Six Months Ended June 30, 2018 As Reported Amount under ASC 605 Effect of Change As Reported Amount under ASC 605 Effect of Change Statement of Operations Revenue $ - $ 166 $ (166 ) $ 3,000 $ 333 $ 2,667 To date, substantially all of the Company’s revenue has been derived from its license agreements with Santen Pharmaceutical Co., Ltd. (Santen) and Ambrx Inc. (Ambrx) as described in Note 6. The terms of these arrangements include 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 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 promised goods or services in the contract; (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 the 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. 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 promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. 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 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. If it is probable that a significant revenue reversal would not occur, the associated milestone payment 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, is not considered probable until the milestones are achieved. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such development 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. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded in revenues when the customer obtains control of the goods, which is upon delivery. 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 payments and fees 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 three and six months ended June 30, 2018 and 2017, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials. Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of employee stock option grants, employee restricted stock unit grants (RSUs) and employee stock purchase plan (ESPP) rights recognized as expense over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The Company estimates the fair value of stock option grants and ESPP rights using the Black-Scholes option pricing model. The fair value of RSUs is based on the stock price on the date of grant. The Company accounts for stock options granted to non-employees using the fair value approach. These option grants, if any, are subject to periodic revaluation over their vesting terms. Comprehensive Income (Loss) Comprehensive income (loss) is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Net income (loss) and comprehensive income (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, as adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded 525 and 785 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the three and six months ended June 30, 2018, respectively, and 7,037 and 8,816 weighted-average shares subject to repurchase for the three and six months ended June 30, 2017, respectively. For all periods presented, there was 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): Six Months Ended June 30, 2018 2017 Warrants to purchase common stock 15,619,113 103,865 Common stock options and restricted stock units 3,125,753 2,498,609 ESPP shares 4,289 7,307 18,749,155 2,609,781 Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting Compensation-Stock Compensation

Short-Term Investments, Cash Eq

Short-Term Investments, Cash Equivalents and Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Short-Term Investments, Cash Equivalents and Fair Value Measurements	2. Short-Term Investments, Cash Equivalents and Fair Value Measurements At June 30, 2018, short-term investments consisted of U.S. treasury securities. The Company classifies all investments as available-for-sale, 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. 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. At June 30, 2018, the remaining contractual maturities of all available-for-sale investments were less than one year. 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. Cash equivalents, which are classified as equity securities, and short-term investments, which are classified as available-for-sale securities, consisted of the following (in thousands): June 30, 2018 December 31, 2017 Cost Unrealized Gain Unrealized (Loss) Estimated Fair Value Cost Unrealized Gain Unrealized (Loss) Estimated Fair Value Money market funds $ 5,603 $ — $ — $ 5,603 $ 5,488 $ — $ — $ 5,488 U.S. treasury securities 18,933 — — 18,933 4,999 — — 4,999 $ 24,536 $ — $ — $ 24,536 $ 10,487 $ — $ — $ 10,487 Classified as: Cash equivalents $ 5,603 $ 5,488 Short-term investments 18,933 4,999 Total Cash equivalents and Short-term investments $ 24,536 $ 10,487 The fair values of the Company’s assets and liabilities, which are measured at fair value on a recurring basis, were determined using the following inputs (in thousands): Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets Other Significant for Identical Observable Unobservable Assets Inputs Inputs Total (Level 1) (Level 2) (Level 3) At June 30, 2018 Money market funds and U.S. treasury securities, included in Cash equivalents and Short-term investments $ 24,536 $ — $ 24,536 $ — At December 31, 2017 Money market funds and U.S. treasury securities, included in Cash equivalents and Short-term investments $ 10,487 $ — $ 10,487 $ —

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2018
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, 2018 2017 Long-term debt $ 7,000 $ 8,000 Less debt discount, net of current portion (742 ) (197 ) Long-term debt, net of debt discount 6,258 7,803 Less current portion of long-term debt - (3,200 ) Long-term debt, net of current portion $ 6,258 $ 4,603 Current portion of long-term debt $ - $ 3,200 Current portion of debt discount - (363 ) Current portion of long-term debt, net $ - $ 2,837 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% per annum. 30 months. 4.0% The 2018 Amended SVB Loan provides for prepayment fees of 3.0% of the amount prepaid if the prepayment occurs on or prior to May 3, 2019, 2.0% 1.0% of the amount prepaid if the prepayment occurs thereafter. Except as described above, the 2018 Amended SVB Loan is subject to the same material terms set forth in the 2017 Amended SVB Loan agreement. Consistent with the terms of the 2017 Amended SVB Loan agreements, 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. In connection with the 2018 Amended SVB Loan, the Company issued SVB a warrant to purchase 53,639 shares of its common stock at an exercise price of $2.61 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 will be recorded as debt discounts and will be amortized to interest expense using the effective interest method over the term of the debt. Future minimum principal and interest payments under the 2018 Amended SVB Loans, including the final payment, are as follows (in thousands): Remaining 2018 $ 320 2019 2,012 2020 3,195 2021 3,218 8,745 Less interest and final payment (1,745 ) Long-term debt $ 7,000

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	4 . Commitments and Contingencies Lonza Biologics Tuas Pte Ltd (Lonza) On February 22, 2017, the Company entered into a long-term manufacturing agreement, or the Manufacturing Agreement, with Lonza for the long term manufacture and supply of registration and commercial batches of TRC105, the Company’s lead drug product candidate. Under the Manufacturing Agreement, Lonza has agreed to manufacture TRC105 pursuant to purchase orders and in accordance with the manufacturing specifications agreed upon between the Company and Lonza. The Company is required to purchase certain batches of TRC105 prior to regulatory approval with a total estimated cost of approximately $15.0 million at June 30, 2018. The Manufacturing Agreement has an initial term beginning on the effective date and ending on the seventh anniversary of the date of first regulatory approval of TRC105 by the FDA or EMA. The Manufacturing Agreement may be renewed for an additional three years upon the written agreement of both parties no later than the fifth anniversary of the date of first approval of TRC105 by the FDA or EMA. Either party may terminate the Manufacturing Agreement due to a material breach of the Manufacturing Agreement by the other party, subject to prior written notice and a cure period, due to the insolvency or bankruptcy of the other party, or due to a force majeure event that prevents performance under the Manufacturing Agreement for at least six months. The Company may terminate the Manufacturing Agreement, subject to 60 days’ written notice, if the Company discontinues the TRC105 program, whether due to a notice of non-approval or withdrawal of marketing approval by a regulatory agency or otherwise. In the event of a termination by the Company due to discontinuation of the TRC105 program or a termination by Lonza due to the Company’s material breach or insolvency or bankruptcy, the Company would be obligated to pay to Lonza certain batch cancellation and/or early termination fees. 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/or sublicensing fees. Each of the license agreements is generally cancelable by the Company, given appropriate prior written notice. At June 30, 2018, potential future milestone payments under these agreements, including future milestone payments associated with assets acquired from Janssen Pharmaceutica N.V. should they not exercise their option to regain their rights to certain assets as discussed in Note 6,

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
Stockholders Equity Note [Abstract]
Stockholders' Equity	5 . Stockholders’ Equity Sales of Common Stock In March and April 2018, the Company sold 11,930,525 shares of its common stock at a purchase price of $2.70 per share, warrants to purchase 1,765,542 shares of its common stock at a purchase price of $2.69 per share and an exercise price of $0.01 per share (the Pre-Funded Warrants) and warrants to purchase 13,696,067 shares of its common stock at a purchase price of $0.125 per share and an exercise price of $2.70 per share (the Common Warrants) for net proceeds of approximately $36.5 million in a private placement to new and certain existing accredited investors. In accordance with their terms, the Pre-Funded Warrants and the Common Warrants may not be exercised if the holder’s ownership of the Company’s common stock would exceed 9.99% or 19.99% of the Company’s total shares outstanding following such exercise, depending on the investor. Both the Pre-Funded Warrants and the Common Warrants were recorded as a component of stockholders’ equity within additional paid-in capital. In April 2018, in connection with this transaction, the Company paid Angel Pond Capital, an affiliate of a holder of more than 5% of the Company’s common stock and an affiliate of a member of the Company’s Board of the Directors, a fee totaling approximately $1.9 million as consideration for acting as a nonexclusive placement agent for this financing. In March 2017, the Company entered into a Common Stock Purchase Agreement (the Purchase Agreement) with Aspire Capital Fund, LLC (Aspire Capital) which provides that, upon the terms and subject to the conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $21.0 million of shares of the Company’s common stock. 222,222 shares of the Company’s common stock to Aspire Capital at $4.50 per share for net proceeds of approximately $0.9 million upon execution of the Purchase Agreement and . In consideration for entering into the Purchase Agreement and concurrently with the execution of the Purchase Agreement, the Company issued 195,726 shares of its common stock to Aspire Capital, the fair value of which was recorded as offering costs in connection with the transaction At-The-Market Issuance Sales Agreement In February 2016, the Company entered into an At-the-Market Equity Offering Sales Agreement (Sales Agreement) with Stifel, Nicolaus & Company, Incorporated (Stifel), pursuant to which it may sell from time to time, at its option, up to an aggregate of $25.0 million of the Company’s shares of its common stock through Stifel, as sales agent. The Company is required to pay Stifel 2.5% of gross proceeds for the common stock sold through the Sales Agreement. During the three and six months ended June 30, 2018, the Company sold no shares of common stock through the Sales Agreement with Stifel and approximately $21.5 million of common stock remains available for sale under the Sales Agreement, 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. Equity Plan Activity During the six months ended June 30, 2018, t he Company issued shares of common stock upon the exercise of outstanding stock options and 38,019 shares of common stock upon the vesting of restricted stock units. The Company withheld 26,304 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, 2018. During the year ended December 31, 2017, the Company issued 53,756 shares of common stock upon the exercise of outstanding stock options. Common Stock Warrants As of June 30, 2018 , the Company had the following outstanding warrants for the purchase of common stock: Expiration Number of shares Exercise price May 13, 2022 18,415 $ 10.86 November 14, 2023 through June 4, 2024 38,758 7.74 January 25, 2024 46,692 5.14 March 27, 2024 13,696,067 2.70 March 27, 2025 1,765,542 0.01 May 3, 2025 53,639 2.61 15,619,113 During the three and six months ended June 30, 2018 and 2017, 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, 2018 2017 2018 2017 Risk-free interest rate 2.7 % 1.8 % 2.8 % 2.1 % Expected volatility 80 % 84 % 80 % 83 % Expected term (in years) 6.1 5.5 6.2 6.2 Expected dividend yield — % — % — % — % Stock compensation expense for the ESPP was immaterial for the three and six months ended June 30, 2018. The allocation of stock-based compensation expense was as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Research and development $ 375 $ 357 $ 739 $ 725 General and administrative 289 438 631 876 $ 664 $ 795 $ 1,370 $ 1,601

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2018
Collaborations Disclosure [Abstract]
Collaborations	6 . Collaborations 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 TRC105. Under the agreement, Santen is permitted to use, develop, manufacture and commercialize TRC105 products for ophthalmology indications, excluding systemic treatment of ocular tumors. Santen also has the right to grant sublicenses to affiliates and third party collaborators. In the event Santen sublicenses any of its rights under the agreement, Santen will be obligated to pay the Company a portion of any upfront and certain milestone payments received under such sublicense. Santen has sole responsibility for funding, developing, seeking regulatory approval for and commercializing TRC105 products in the field of ophthalmology. In the event that Santen fails to meet certain commercial diligence obligations, the Company will have the option to co-promote TRC105 products in the field of ophthalmology in the United States with Santen. If the Company exercises this option, the Company will pay Santen a percentage of certain development expenses, and the Company will receive a percentage of profits from sales of the licensed products in the ophthalmology field in the United States, but will 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 is 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 relates to the initiation of certain development activities, $52.5 million relates to the submission of certain regulatory filings and receipt of certain regulatory approvals and $82.5 million relates to commercialization activities and the achievement of specified levels of product sales. As of June 30, 2018 and December 31, 2017, two development milestones had been received totaling $10.0 million. If TRC105 products are successfully commercialized in the field of ophthalmology, Santen will be 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 will reimburse the Company for all royalties due by the Company under certain third party agreements with respect to the use, manufacture or commercialization of TRC105 products in the field of ophthalmology by Santen and its affiliates and sublicensees. Royalties will continue on a country-by-country basis through the later of the expiration of the Company’s patent rights applicable to the TRC105 products in a given country or 12 years after the first commercial sale of the first TRC105 product commercially launched in such country. Santen may unilaterally terminate this agreement in its entirety, or on a country-by-country basis, upon written notice to the Company. Either party may terminate the agreement in the event of the other party’s bankruptcy or dissolution or for the other party’s material breach of the agreement that remains uncured 90 days (or 30 days with respect to a payment breach) after receiving notice from the non-breaching party. Unless earlier terminated, the agreement continues in effect until the termination of Santen’s payment obligations. Upon the adoption of ASU 2014-09, 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 TRC105, (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. Upon the adoption of ASC 2014-09 and as of June 30, 2018, the transaction price includes 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 are fully constrained as the achievement of the milestones is not considered probable. In addition, in accordance with ASU 2014-09, a ny 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. As of December 31, 2017, the Company had satisfied all of its performance obligations and recognized the full transaction price, and accordingly, no adjustment was required to retained earnings under the modified retrospective approach used upon the adoption of ASC 2014-09. Revenue recognized related to this agreement totaled $0 for the three and six months ended June 30, 2018, and $0.6 million and $1.3 million for the three and six months ended June 30, 2017, respectively. Janssen Pharmaceutica N.V. (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, and, together with the AR Mutant Program, the Programs). With respect to the AR Mutant Program, Janssen maintains an option, which is exercisable until 90 days after the Company demonstrates clinical proof of concept, 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. If Janssen exercises the option, Janssen will be obligated to pay the Company (i) a one-time option exercise fee of $45.0 million; (ii) regulatory and commercial based milestone payments totaling up to $137.5 million upon achievement of specified events; and (iii) royalties in the low single digits on annual net sales of AR Mutant Program products. If Janssen does not exercise the option, the Company would then have the right to retain worldwide development and commercialization rights to the AR Mutant Program, in which case, the Company would be 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. With respect to the NIK Program, Janssen maintains a right, which is exercisable within 90 days following the date on which the Company demonstrates clinical proof of concept with respect to the NIK Program, to negotiate exclusively for a period of six months for a reversion of the related rights in the licensed intellectual property and to obtain an exclusive license to commercialize the compounds and certain other specified intellectual property developed under the NIK Program. If Janssen does not exercise its right of first negotiation, or, if after exercise of such right, the Company and Janssen are unable to reach an agreement on the terms of a reversion and exclusive license, and, in either case, the Company continues the development of the NIK Program, then the Company would be obligated to pay Janssen (i) development and regulatory based milestone payments totaling up to $60.0 million upon achievement of specified events, and (ii) royalties in the low single digits based on annual net sales of NIK 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 Programs according to agreed upon development plans, timelines and budgets. For each Program that the Company retains, the Company is further obligated 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 or the NIK Program, as applicable, 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 or the NIK Program, as applicable, 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 (a) with respect to the AR Mutant Program, upon Janssen exercising its option in respect of the AR Mutant Program and making payment of the option exercise fee to the Company or, if Janssen does not exercise the option, upon the expiration of all payment obligations of the Company to Janssen with respect of the AR Mutant Program, and (b) with respect to the NIK Program, upon the Company and Janssen entering into an exclusive license agreement following Janssen’s exercise of its right of first negotiation or, if Janssen’s right of first negotiation with respect to the NIK Program expires and the Company and Janssen have not entered into an exclusive license agreement, upon the expiration of all payment obligations of the Company to Janssen with respect of the NIK Program. The Company may also terminate a Program or the License and Option Agreement in its entirety without cause, subject to specified conditions. Ambrx Inc. (Ambrx) In December 2017, the Company entered into a license agreement with Ambrx Inc. (Ambrx), for the development and commercialization of the Company’s endoglin antibodies, including TRC105, in China. The license grants Ambrx the exclusive rights to use, develop, manufacture and commercialize the Company’s endoglin antibodies in all indications (excluding ophthalmology which are held by Santen) in China (including Hong Kong and Macau) and Taiwan, or the Ambrx Territory. Ambrx also has the right to grant sublicenses to affiliates and third party collaborators, provided such sublicenses are consistent with the terms of the Company’s agreement and excluding the rights licensed to the Company under the license with Lonza. Ambrx has sole responsibility for funding, developing, seeking regulatory approval for and commercializing TRC105 products in the Ambrx Territory. Ambrx has the option to either pursue a China only development strategy at its sole expense, or upon mutual agreement of the Company and Ambrx, participate in the Company’s ongoing global Phase 3 TAPPAS clinical trial in angiosarcoma by enrolling patients in this trial, and the Company may participate in an Ambrx-sponsored clinical trial in hepatocellular carcinoma, or any other indication Ambrx pursues in the Ambrx Territory. In consideration of the rights granted to Ambrx under the agreement, the Company received a one-time upfront fee of $3.0 million. In addition, the Company is eligible to receive up to a total of $140.5 million in milestone payments upon the achievement of certain milestones, of which $10.5 million relates to the submission of certain regulatory filings and receipt of certain regulatory approvals and $130.0 million relates to the achievement of specified levels of product sales. If TRC105 products are successfully commercialized in the territory, Ambrx will be 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. Royalties will continue on a country-by-country basis through the later of the expiration of the Company’s patent rights applicable to the TRC105 products in a given country or 12 years after the first commercial sale of the first TRC105 product commercially launched in such country. Ambrx may unilaterally terminate this agreement in its entirety for any reason or for no reason upon at least 90 days’ notice to the Company. Either party may terminate the agreement in the event of the other party’s bankruptcy or dissolution or for the other party’s material breach of the agreement that remains uncured 60 days (or 30 days with respect to a payment breach) after receiving notice from the non-breaching party. Unless earlier terminated, the agreement continues in effect until the termination of Ambrx’s payment obligations. Upon the adoption of ASU 2014-09, 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 TRC105 and (2) a collaboration, including technical and regulatory support provided by the Company. In addition, customer options were identified that include manufacturing and supply obligations. Upon the adoption of ASU 2014-09 and as of June 30, 2018, the transaction price consisted solely of the $3.0 million upfront payment. The remaining $10.5 million of potential regulatory milestone payments are fully constrained as the achievement of the milestones is not considered probable. In addition, in accordance with ASU 2014-09, a ny consideration related to the sales-based milestones (including royalties) will be recognized when the related sales occur and therefore, 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. At December 31, 2017, the $3.0 million upfront payment had been received and was recorded as deferred revenue in the accompanying condensed consolidated balance sheet. The license and know-how related to TRC105 was delivered to Ambrx in the first quarter of 2018. The Company recognized $0 and $3.0 million for the three and six months ended June 30, 2018, respectively.

Organization and Summary of S12

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
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 and wet age-related macular degeneration. The Company’s lead product candidate is an antibody that binds to the endoglin receptor, which is essential to angiogenesis (the process of new blood vessel formation). The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, TRACON Pharma Limited, which was formed in September 2015 and is currently inactive. All significant intercompany accounts and transactions have been eliminated.
Basis of Presentation	Basis of Presentation As of June 30, 2018, 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, 2018, the Company had an accumulated deficit of $122.8 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, 2018, the Company had cash, cash equivalents and short-term investments of $53.4 million. Based on the Company’s current business plan, management believes that existing cash, cash equivalents and short-term investments will be sufficient to fund the Company’s obligations for at least 12 months after the release date of these condensed consolidated financial statements. The completion of the private placement of the Company’s common stock and warrants in March and April 2018, which generated net proceeds totaling $36.5 million, resolved the substantial doubt about the Company’s ability to continue as a going concern which existed at the reporting date of the December 31, 2017 consolidated financial statements. The Company plans to continue to fund its losses from operations through cash, cash equivalents and investments on hand, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements, including equity financing through the common stock purchase agreement the Company entered into with Aspire Capital Fund, LLC in March 2017 for the purchase of up to $21.0 million of the Company’s common stock over a 30-month period and/or the at-the-market equity offering sales agreement the Company entered into with Stifel, Nicolaus & Company, Incorporated in February 2016 for the sale of up to $25.0 million of the Company’s common stock, of which approximately $21.5 million remains available for sale 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 Even if the Company raises additional capital, it may also be required to modify, delay or abandon some of its plans which could have a material adverse effect on the Company’s business, operating results and financial condition and the Company’s ability to achieve its intended business objectives. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Unaudited Interim Financial Information The unaudited condensed consolidated financial statements at June 30, 2018, and for the three and six months ended June 30, 2018 and 2017, 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. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2017, included in its Annual Report on Form 10-K filed with the SEC on March 1, 2018.
Use of Estimates	Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with 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 and the disclosure of contingent assets and liabilities in the Company’s financial statements and accompanying notes. The most significant estimates in the Company’s financial statements relate to revenue recognition, expenses incurred for clinical trials and the valuation of equity awards. 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, as well as U.S. treasury securities.
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 Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09) , which supersedes all existing revenue recognition requirements, . This new standard requires a company to recognize revenues when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. ASU 2014-09 was applied to all contracts on January 1, 2018, the date of adoption. did not identify any accounting changes that impacted the amount of historically reported retained earnings therefore no adjustment to retained earnings was required upon adoption. The following is the total revenue that would have been recorded in the three and six months ended June 30, 2018 under the superseded revenue recognition guidance, Accounting Standards Codification 605, Revenue Recognition (ASC 605) , had ASU 2014-09 not been adopted (in thousands): For the Three Months Ended June 30, 2018 For the Six Months Ended June 30, 2018 As Reported Amount under ASC 605 Effect of Change As Reported Amount under ASC 605 Effect of Change Statement of Operations Revenue $ - $ 166 $ (166 ) $ 3,000 $ 333 $ 2,667 To date, substantially all of the Company’s revenue has been derived from its license agreements with Santen Pharmaceutical Co., Ltd. (Santen) and Ambrx Inc. (Ambrx) as described in Note 6. The terms of these arrangements include 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 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 promised goods or services in the contract; (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 the 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. 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 promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. 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 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. If it is probable that a significant revenue reversal would not occur, the associated milestone payment 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, is not considered probable until the milestones are achieved. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such development 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. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded in revenues when the customer obtains control of the goods, which is upon delivery. 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 payments and fees 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 three and six months ended June 30, 2018 and 2017, there were no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of employee stock option grants, employee restricted stock unit grants (RSUs) and employee stock purchase plan (ESPP) rights recognized as expense over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The Company estimates the fair value of stock option grants and ESPP rights using the Black-Scholes option pricing model. The fair value of RSUs is based on the stock price on the date of grant. The Company accounts for stock options granted to non-employees using the fair value approach. These option grants, if any, are subject to periodic revaluation over their vesting terms.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Net income (loss) and comprehensive income (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, as adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded 525 and 785 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the three and six months ended June 30, 2018, respectively, and 7,037 and 8,816 weighted-average shares subject to repurchase for the three and six months ended June 30, 2017, respectively. For all periods presented, there was 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): Six Months Ended June 30, 2018 2017 Warrants to purchase common stock 15,619,113 103,865 Common stock options and restricted stock units 3,125,753 2,498,609 ESPP shares 4,289 7,307 18,749,155 2,609,781
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting Compensation-Stock Compensation

Organization and Summary of S13

Organization and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
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): Six Months Ended June 30, 2018 2017 Warrants to purchase common stock 15,619,113 103,865 Common stock options and restricted stock units 3,125,753 2,498,609 ESPP shares 4,289 7,307 18,749,155 2,609,781
Accounting Standards Update (ASU) No. 2014-09
Schedule of Revenue Recognition Guidance Accounting Standards	Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09) , which supersedes all existing revenue recognition requirements, . This new standard requires a company to recognize revenues when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. ASU 2014-09 was applied to all contracts on January 1, 2018, the date of adoption. did not identify any accounting changes that impacted the amount of historically reported retained earnings therefore no adjustment to retained earnings was required upon adoption. The following is the total revenue that would have been recorded in the three and six months ended June 30, 2018 under the superseded revenue recognition guidance, Accounting Standards Codification 605, Revenue Recognition (ASC 605) , had ASU 2014-09 not been adopted (in thousands): For the Three Months Ended June 30, 2018 For the Six Months Ended June 30, 2018 As Reported Amount under ASC 605 Effect of Change As Reported Amount under ASC 605 Effect of Change Statement of Operations Revenue $ - $ 166 $ (166 ) $ 3,000 $ 333 $ 2,667

Short-Term Investments, Cash 14

Short-Term Investments, Cash Equivalents and Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Available-for-sale Securities	Cash equivalents, which are classified as equity securities, and short-term investments, which are classified as available-for-sale securities, consisted of the following (in thousands): June 30, 2018 December 31, 2017 Cost Unrealized Gain Unrealized (Loss) Estimated Fair Value Cost Unrealized Gain Unrealized (Loss) Estimated Fair Value Money market funds $ 5,603 $ — $ — $ 5,603 $ 5,488 $ — $ — $ 5,488 U.S. treasury securities 18,933 — — 18,933 4,999 — — 4,999 $ 24,536 $ — $ — $ 24,536 $ 10,487 $ — $ — $ 10,487 Classified as: Cash equivalents $ 5,603 $ 5,488 Short-term investments 18,933 4,999 Total Cash equivalents and Short-term investments $ 24,536 $ 10,487
Schedule of assets and liabilities measured at fair value on a recurring basis	The fair values of the Company’s assets and liabilities, which are measured at fair value on a recurring basis, were determined using the following inputs (in thousands): Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets Other Significant for Identical Observable Unobservable Assets Inputs Inputs Total (Level 1) (Level 2) (Level 3) At June 30, 2018 Money market funds and U.S. treasury securities, included in Cash equivalents and Short-term investments $ 24,536 $ — $ 24,536 $ — At December 31, 2017 Money market funds and U.S. treasury securities, included in Cash equivalents and Short-term investments $ 10,487 $ — $ 10,487 $ —

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
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, 2018 2017 Long-term debt $ 7,000 $ 8,000 Less debt discount, net of current portion (742 ) (197 ) Long-term debt, net of debt discount 6,258 7,803 Less current portion of long-term debt - (3,200 ) Long-term debt, net of current portion $ 6,258 $ 4,603 Current portion of long-term debt $ - $ 3,200 Current portion of debt discount - (363 ) Current portion of long-term debt, net $ - $ 2,837
Schedule of future minimum principal and interest payments	Future minimum principal and interest payments under the 2018 Amended SVB Loans, including the final payment, are as follows (in thousands): Remaining 2018 $ 320 2019 2,012 2020 3,195 2021 3,218 8,745 Less interest and final payment (1,745 ) Long-term debt $ 7,000

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Stockholders Equity Note [Abstract]
Schedule of outstanding warrants for purchase of common stock issued	As of June 30, 2018 , the Company had the following outstanding warrants for the purchase of common stock: Expiration Number of shares Exercise price May 13, 2022 18,415 $ 10.86 November 14, 2023 through June 4, 2024 38,758 7.74 January 25, 2024 46,692 5.14 March 27, 2024 13,696,067 2.70 March 27, 2025 1,765,542 0.01 May 3, 2025 53,639 2.61 15,619,113
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, 2018 2017 2018 2017 Risk-free interest rate 2.7 % 1.8 % 2.8 % 2.1 % Expected volatility 80 % 84 % 80 % 83 % Expected term (in years) 6.1 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, 2018 2017 2018 2017 Research and development $ 375 $ 357 $ 739 $ 725 General and administrative 289 438 631 876 $ 664 $ 795 $ 1,370 $ 1,601

Organization and Summary of S17

Organization and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Feb. 29, 2016
Basis of Presentation
Accumulated deficit		$ (122,819,000)		$ (122,819,000)		$ (104,701,000)
Cash, cash equivalents and short-term investments		$ 53,400,000		$ 53,400,000
Weighted-average shares subject to repurchase or forfeiture (in shares)		525	7,037	785	8,816
Common Stock and Warrants
Basis of Presentation
Net proceeds received in private placement				$ 36,500,000
Common Stock | Stifel, Nicolaus & Company, Incorporated | At-the-Market Equity Offering Sales Agreement
Basis of Presentation
Maximum aggregate value of stock to be sold							$ 25,000,000
Common stock remains available for sale		$ 21,500,000		$ 21,500,000
Common Stock | Aspire Capital
Basis of Presentation
Maximum aggregate value of stock to be purchase	$ 21,000,000
Sale duration for common stock under purchase agreement	30 months

Organization and Summary of S18

Organization and Summary of Significant Accounting Policies - Schedule of Revenue Recognition Guidance Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue		$ 631	$ 3,000	$ 1,257
Type of Revenue [Extensible List]	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember
Accounting Standards Update (ASU) No. 2014-09 | Amount Under ASC 605
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 166		$ 333
Accounting Standards Update (ASU) No. 2014-09 | Effect of Change
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ (166)		$ 2,667

Organization and Summary of S19

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, 2018	Jun. 30, 2017
Antidilutive securities
Antidilutive securities	18,749,155	2,609,781
Warrants to Purchase Common Stock
Antidilutive securities
Antidilutive securities	15,619,113	103,865
Common Stock Options and Restricted Stock Units
Antidilutive securities
Antidilutive securities	3,125,753	2,498,609
ESPP Shares
Antidilutive securities
Antidilutive securities	4,289	7,307

Short-Term Investments, Cash 20

Short-Term Investments, Cash Equivalents and Fair Value Measurements - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018USD ($)
Fair Value Disclosures [Abstract]
Maximum period for remaining contractual maturities of available-for-sale investments	1 year
Amount of transfers between levels	$ 0

Short-Term Investments, Cash 21

Short-Term Investments, Cash Equivalents and Fair Value Measurements - Schedule of Available for Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Short-Term Investments, Cash Equivalents and Fair Value Measurements
Cost	$ 24,536	$ 10,487
Estimated Fair Value	24,536	10,487
Short-term investments	18,933	4,999
Estimated Fair Value
Short-Term Investments, Cash Equivalents and Fair Value Measurements
Cash equivalents	5,603	5,488
Short-term investments	18,933	4,999
Money market funds
Short-Term Investments, Cash Equivalents and Fair Value Measurements
Cost	5,603	5,488
Estimated Fair Value	5,603	5,488
U.S. treasury securities
Short-Term Investments, Cash Equivalents and Fair Value Measurements
Cost	18,933	4,999
Estimated Fair Value	$ 18,933	$ 4,999

Short-Term Investments, Cash 22

Short-Term Investments, Cash Equivalents and Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - Money market funds and U.S. treasury securities, included in Cash equivalents and Short-term investments - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets:
Fair value, assets	$ 24,536	$ 10,487
Level 2
Assets:
Fair value, assets	$ 24,536	$ 10,487

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, 2018	Dec. 31, 2017
Long-term debt
Long-term debt	$ 7,000	$ 8,000
Less debt discount, net of current portion	(742)	(197)
Long-term debt, net of debt discount	6,258	7,803
Less current portion of long-term debt		(3,200)
Long-term debt, net of current portion	$ 6,258	4,603
Current portion of long-term debt		3,200
Current portion of debt discount		(363)
Current portion of long-term debt, net		$ 2,837

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	1 Months Ended	6 Months Ended
	May 31, 2018	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Proceeds from long-term debt		$ 7,000,000	$ 8,000,000
Warrants issued		15,619,113
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	53,639
Exercise price (per share)	$ 2.61
2018 SVB Loan | Silicon Valley Bank | Prior to May 3, 2019
Debt Instrument [Line Items]
Prepayment fee (as a percent)	3.00%
2018 SVB Loan | Silicon Valley Bank | After May 3, 2018 Prior to May 3, 2020
Debt Instrument [Line Items]
Prepayment fee (as a percent)	2.00%
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

Long-Term Debt - Schedule of Fu

Long-Term Debt - Schedule of Future Minimum Principal and Interest Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 7,000	$ 8,000
2018 Amended SVB Loan
Debt Instrument [Line Items]
Remaining 2,018	320
2,019	2,012
2,020	3,195
2,021	3,218
Long Term Debt Including Final Payment	8,745
Less interest and final payment	(1,745)
Long-term debt	$ 7,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	Feb. 22, 2017	Jun. 30, 2018
Commitments and Contingencies
Non-cancelable purchase obligations		$ 5.5
Long-term manufacturing agreement description		Either party may terminate the Manufacturing Agreement due to a material breach of the Manufacturing Agreement by the other party, subject to prior written notice and a cure period, due to the insolvency or bankruptcy of the other party, or due to a force majeure event that prevents performance under the Manufacturing Agreement for at least six months. The Company may terminate the Manufacturing Agreement, subject to 60 days’ written notice, if the Company discontinues the TRC105 program, whether due to a notice of non-approval or withdrawal of marketing approval by a regulatory agency or otherwise. In the event of a termination by the Company due to discontinuation of the TRC105 program or a termination by Lonza due to the Company’s material breach or insolvency or bankruptcy, the Company would be obligated to pay to Lonza certain batch cancellation and/or early termination fees.
Prior written notice for termination on the breach of agreement period	60 days
Research and development arrangement
Commitments and Contingencies
Potential milestone payable		$ 126
Prior to Approval
Commitments and Contingencies
Long-Term manufacturing agreement for lead purchase of product candidate batches estimated annual cost		15
Regulatory Approval
Commitments and Contingencies
Long-Term manufacturing agreement for lead purchase of product candidate batches estimated annual cost		$ 22

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	May 01, 2017	Apr. 30, 2018	Mar. 31, 2018	Mar. 31, 2017	Feb. 29, 2016	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Conversion of warrants to purchase shares						15,619,113	15,619,113
Angel Pond Capital
Class Of Stock [Line Items]
Related party transaction, description of transaction							Company paid Angel Pond Capital, an affiliate of a holder of more than 5% of the Company’s common stock and an affiliate of a member of the Company’s Board of the Directors, a fee totaling approximately $1.9 million as consideration for acting as a nonexclusive placement agent for this financing
Payment of placement agent fee		$ 1,900,000
Pre-Funded Warrants and Common Warrants
Class Of Stock [Line Items]
Maximum percentage of holders ownership interest in common stock to exercise warrants.		9.99%	9.99%
Maximum percentage of holders ownership interest in common stock after exercise		19.99%	19.99%
Common Stock | Equity Plan Activity
Class Of Stock [Line Items]
Shares issued upon exercise of outstanding stock options							125,474	53,756
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							26,304
Shares issued upon vesting of restricted stock units							38,019
Common Stock | Aspire Capital
Class Of Stock [Line Items]
Stock issued during period, shares, new issues	195,726			222,222
Shares issued, price per share				$ 4.50
Maximum aggregate value of stock to be purchase				$ 21,000,000
Sale duration for common stock under purchase agreement	30 months
Proceeds from sale of common stock				$ 900,000
Maximum value of additional shares committed to purchase	$ 20,000,000
Private Placement | Common Stock
Class Of Stock [Line Items]
Stock issued during period, shares, new issues		11,930,525	11,930,525
Shares issued, price per share		$ 2.70	$ 2.70
Net proceeds received in private placement		$ 36,500,000	$ 36,500,000
Private Placement | Common Stock | Pre-Funded Warrants
Class Of Stock [Line Items]
Shares issued, price per share		$ 2.69	$ 2.69
Conversion of warrants to purchase shares		1,765,542	1,765,542
Exercise price (per share)		$ 0.01	$ 0.01
Private Placement | Common Stock | Common Warrants
Class Of Stock [Line Items]
Shares issued, price per share		$ 0.125	$ 0.125
Conversion of warrants to purchase shares		13,696,067	13,696,067
Exercise price (per share)		$ 2.70	$ 2.70
At-the-Market Equity Offering Sales Agreement | Common Stock | Stifel, Nicolaus & Company, Incorporated
Class Of Stock [Line Items]
Stock issued during period, shares, new issues						0	0
Maximum aggregate value of stock to be sold					$ 25,000,000
Percentage of gross proceeds, required to pay for common stock sold through sales agreement					2.50%
Common stock remains available for sale						$ 21,500,000	$ 21,500,000
Period over which limited value of shares subjected to sell under form S-3							12 months

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Outstanding Warrants for Purchase of Common Stock Issued (Details)	Jun. 30, 2018$ / sharesshares
Class Of Stock [Line Items]
Warrants issued	15,619,113
May 13, 2022
Class Of Stock [Line Items]
Warrants issued	18,415
Exercise price (per share) | $ / shares	$ 10.86
November 14, 2023 Through June 4, 2024
Class Of Stock [Line Items]
Warrants issued	38,758
Exercise price (per share) | $ / shares	$ 7.74
January 25, 2024
Class Of Stock [Line Items]
Warrants issued	46,692
Exercise price (per share) | $ / shares	$ 5.14
March 27, 2024
Class Of Stock [Line Items]
Warrants issued	13,696,067
Exercise price (per share) | $ / shares	$ 2.70
March 27, 2025
Class Of Stock [Line Items]
Warrants issued	1,765,542
Exercise price (per share) | $ / shares	$ 0.01
May 3, 2025
Class Of Stock [Line Items]
Warrants issued	53,639
Exercise price (per share) | $ / shares	$ 2.61

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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Class Of Stock [Line Items]
Risk-free interest rate	2.70%	1.80%	2.80%	2.10%
Expected volatility	80.00%	84.00%	80.00%	83.00%
Expected term (in years)	6 years 1 month 6 days	5 years 6 months	6 years 2 months 12 days	6 years 2 months 12 days
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Stockholders' Equity - Summar30

Stockholders' Equity - Summary of Allocation of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Class Of Stock [Line Items]
Stock based compensation expense	$ 664	$ 795	$ 1,370	$ 1,601
Research and development
Class Of Stock [Line Items]
Stock based compensation expense	375	357	739	725
General and administrative
Class Of Stock [Line Items]
Stock based compensation expense	$ 289	$ 438	$ 631	$ 876

Collaborations - Additional Inf

Collaborations - Additional Information (Details)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2017USD ($)	Mar. 31, 2014USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)Milestone	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contracts Revenue				$ 631,000	$ 3,000,000	$ 1,257,000
Type of Revenue [Extensible List]			tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember
Janssen Pharmaceutica N.V.
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 (a) with respect to the AR Mutant Program, upon Janssen exercising its option in respect of the AR Mutant Program and making payment of the option exercise fee to the Company or, if Janssen does not exercise the option, upon the expiration of all payment obligations of the Company to Janssen with respect of the AR Mutant Program, and (b) with respect to the NIK Program, upon the Company and Janssen entering into an exclusive license agreement following Janssen’s exercise of its right of first negotiation or, if Janssen’s right of first negotiation with respect to the NIK Program expires and the Company and Janssen have not entered into an exclusive license agreement, upon the expiration of all payment obligations of the Company to Janssen with respect of the NIK Program. The Company may also terminate a Program or the License and Option Agreement in its entirety without cause, subject to specified conditions.
Janssen Pharmaceutica N.V. | License and Option Agreement | AR Mutant Program
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Exercisable period					90 days
License and option agreement terms					Janssen will be obligated to pay the Company (i) a one-time option exercise fee of $45.0 million; (ii) regulatory and commercial based milestone payments totaling up to $137.5 million upon achievement of specified events; and (iii) royalties in the low single digits on annual net sales of AR Mutant Program products.
One-time option exercise fee					$ 45,000,000
Regulatory and commercial based milestone payments					137,500,000
Development and regulatory based milestone payments					$ 45,000,000
Janssen Pharmaceutica N.V. | License and Option Agreement | NIK Program
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Exercisable period					90 days
License and option agreement terms					The Company would be obligated to pay Janssen (i) development and regulatory based milestone payments totaling up to $60.0 million upon achievement of specified events, and (ii) royalties in the low single digits based on annual net sales of NIK Program products, subject to certain specified reductions.
Development and regulatory based milestone payments					$ 60,000,000
Consideration exchanged for assets acquired					0
Value given to assets acquired			$ 0		$ 0
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
Cure period for bankruptcy or dissolution					90 days
Cure period for breach of payment					30 days
Type of Revenue [Extensible List]			tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember	tcon:CollaborationMember
Collaborative Arrangement | Santen | Accounting Standards Update (ASU) No. 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments recognized as revenue							$ 10,000,000
Contracts Revenue			$ 0	$ 600,000	$ 0	$ 1,300,000
Adjustment to retained earnings upon adoption of ASC 2014-09	$ 0						0
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 | Accounting Standards Update (ASU) No. 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
Collaborative Arrangement | Ambrx, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One-time upfront fee	3,000,000
Potential milestone that could be received	140,500,000						140,500,000
Royalty continuation term					12 years
Cure period for bankruptcy or dissolution					60 days
Cure period for breach of payment					30 days
Deferred revenue	3,000,000						3,000,000
Collaboration revenue recognized			$ 0		$ 3,000,000
Collaborative Arrangement | Ambrx, Inc. | Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone that could be received	10,500,000						10,500,000
Collaborative Arrangement | Ambrx, Inc. | Product Sales Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone that could be received	$ 130,000,000						$ 130,000,000