Nature of Business	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. NATURE OF BUSINESS Organization Histogenics Corporation (the “Company”) was incorporated under the laws of the Commonwealth of Massachusetts on June 28, 2000 and has its principal operations in Waltham, Massachusetts. In 2006, the Company’s board of directors approved a corporate reorganization pursuant to which the Company incorporated as a Delaware corporation. The Company is a leader in the development of restorative cell therapies (“RCTs”). RCTs refer to a new class of products the Company is developing that are designed to offer patients rapid-onset pain relief and restored function through the repair of damaged or worn tissue. NeoCart, the Company’s lead investigational product, is an innovative cell therapy that utilizes various aspects of the Company’s RCT technology platform to treat tissue injury in the field of orthopedics, specifically cartilage damage in the knee. NeoCart is designed to rebuild a patient’s own knee cartilage to treat pain at the source, improve function and potentially prevent a patient’s progression to osteoarthritis. NeoCart is one of the most rigorously studied restorative cell therapies for orthopedic use and is currently in a 249 patient, Phase 3 clinical trial in the United States (the “U.S.”) under a special protocol assessment with the U.S. Food and Drug Administration (the “FDA”). In the third quarter of 2018, the Company announced that its Phase 3 clinical trial of NeoCart did not meet the primary endpoint of a statistically significant improvement in pain and function in a dual threshold responder analysis one year after treatment as compared to microfracture. However, NeoCart did demonstrate statistically significant and clinically meaningful improvements on the dual threshold responder analysis six months after treatment and on nearly all individual pain and function measures when compared to microfracture one and two years after treatment. As a result, the Company met with the FDA on October 30, 2018 to discuss the data and a potential Biologics License Application (“BLA”) submission. The FDA has not made a final decision regarding a potential BLA submission. The Company and the FDA are continuing to discuss the clinical data generated to date, the potential need for any additional supplemental clinical data (which may include longer-term data from the ongoing Phase 3 clinical trial or additional studies) and potential alternative regulatory pathways for the BLA to be accepted. On December 18, 2014, the Company formed a wholly owned subsidiary, Histogenics Securities Corporation, under the laws of the Commonwealth of Massachusetts. On September 29, 2016, the Company closed a private placement of common stock, preferred stock and warrants, contemplated by a securities purchase agreement dated September 15, 2016, with certain institutional and accredited investors. The net proceeds after deducting placement agent fees and other transaction-related expenses was $27.6 million. See Note 6, Capital Stock, for further discussion of the private placement. In January 2018, the Company completed an underwritten registered direct offering of 2,691,494 shares of common stock. The total net proceeds of the offering were $5.7 million after deducting underwriter’s discounts and commissions, and expenses related to the offering. In March 2018, the Company entered into an equity distribution agreement (“ATM Agreement”) with Canaccord Genuity Inc. (“Canaccord”), pursuant to which the Company may, from time to time, sell shares of its common stock having an aggregate offering price of up to $10.0 million (the “Shares”) through Canaccord, as sales agent. During the nine months ended September 30, 2018, the Company sold an aggregate of 5,766,247 shares of common stock and received $4.0 million after deducting commissions related to the ATM Agreement and other offering costs. From October 1, 2018 through November 6, 2018, the Company sold an aggregate of 867,656 shares of its common stock and received $0.5 million after deducting commissions related to the ATM Agreement. On October 10, 2018, the Company closed an underwritten public offering of 26,155,000 shares of its common stock and warrants to purchase up to 19,616,250 shares of common stock, at a combined purchase price of $0.65 per share of common stock and accompanying warrant. The gross proceeds from this offering were $17.0 million, before deducting underwriting discounts and commissions, and offering expenses payable by the Company. The warrants are exercisable immediately upon issuance at a price of $0.70 per share of common stock and have a term of five years commencing on the date of issuance. Since its inception, the Company has devoted substantially all of its efforts to product development, recruiting management and technical staff, raising capital, starting up production and building infrastructure and has not yet generated revenues from its planned principal operations. Expenses have primarily been for research and development and related administrative costs. The Company is subject to a number of risks. The developmental nature of its activities is such that significant inherent risks exist in the Company’s operations. Principal among these risks are the successful development of therapeutics, ability to obtain adequate financing, obtaining regulatory approval for any of its product candidates in any jurisdiction, obtaining adequate reimbursement rates for any of its approved product candidates, compliance with government regulations, protection of proprietary therapeutics, fluctuations in operating results, dependence on key personnel and collaborative partners, adoption of the Company’s products by the physician community, rapid technological changes inherent in the markets targeted, the introduction of substitute products and competition from larger companies. Liquidity The consolidated financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As shown in the accompanying consolidated financial statements, the Company had an accumulated deficit at September 30, 2018 of $216.0 million and has incurred losses and cash flow deficits from operations for the nine months ended September 30, 2018 and 2017. The Company has financed operations to date primarily through public and private placements of equity securities, and borrowings under debt agreements. The Company anticipates that it will continue to incur net losses for the next several years. The Company believes that its existing cash, cash equivalents and marketable securities will only be sufficient to fund its projected cash needs into the middle of 2019. Accordingly, these factors, among others, raise substantial doubt about the Company’s ability to continue as a going concern. The Company will require additional capital to sustain operations through FDA approval of NeoCart and to commercialize NeoCart, if approved. To meet its capital needs, the Company intends to raise additional capital through debt or equity financing or other strategic transactions. However, such financing may not be on favorable terms or available to the Company. The failure of the Company to obtain sufficient funds on commercially acceptable terms when needed will have a material adverse effect on the Company’s business, results of operations and financial condition. The forecast of cash resources is forward-looking information that involves risks and uncertainties, and the actual amount of our expenses could vary materially and adversely as a result of a number of factors. The Company has based its estimates on assumptions that may prove to be wrong, and the Company’s expenses could prove to be significantly higher than it currently anticipates. Basis of Accounting The consolidated financial statements are unaudited and have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). However, they do not include all of the information and footnotes required by GAAP for complete financial statements. These interim consolidated financial statements, in the opinion of the Company’s management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended September 30, 2018 and 2017. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 15, 2018. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, ProChon and Histogenics Securities Corporation. All significant intercompany accounts and transactions are eliminated in consolidation.

1. NATURE OF BUSINESS

Organization

Histogenics Corporation (the “Company”) was incorporated under the laws of the Commonwealth of Massachusetts on June 28, 2000 and has its principal operations in Waltham, Massachusetts. In 2006, the Company’s board of directors approved a corporate reorganization pursuant to which the Company incorporated as a Delaware corporation. The Company is a leader in the development of restorative cell therapies (“RCTs”). RCTs refer to a new class of products the Company is developing that are designed to offer patients rapid-onset pain relief and restored function through the repair of damaged or worn tissue. NeoCart, the Company’s lead investigational product, is an innovative cell therapy that utilizes various aspects of the Company’s RCT technology platform to treat tissue injury in the field of orthopedics, specifically cartilage damage in the knee. NeoCart is designed to rebuild a patient’s own knee cartilage to treat pain at the source, improve function and potentially prevent a patient’s progression to osteoarthritis. NeoCart is one of the most rigorously studied restorative cell therapies for orthopedic use and is currently in a 249 patient, Phase 3 clinical trial in the United States (the “U.S.”) under a special protocol assessment with the U.S. Food and Drug Administration (the “FDA”). In the third quarter of 2018, the Company announced that its Phase 3 clinical trial of NeoCart did not meet the primary endpoint of a statistically significant improvement in pain and function in a dual threshold responder analysis one year after treatment as compared to microfracture. However, NeoCart did demonstrate statistically significant and clinically meaningful improvements on the dual threshold responder analysis six months after treatment and on nearly all individual pain and function measures when compared to microfracture one and two years after treatment. As a result, the Company met with the FDA on October 30, 2018 to discuss the data and a potential Biologics License Application (“BLA”) submission. The FDA has not made a final decision regarding a potential BLA submission. The Company and the FDA are continuing to discuss the clinical data generated to date, the potential need for any additional supplemental clinical data (which may include longer-term data from the ongoing Phase 3 clinical trial or additional studies) and potential alternative regulatory pathways for the BLA to be accepted.

On December 18, 2014, the Company formed a wholly owned subsidiary, Histogenics Securities Corporation, under the laws of the Commonwealth of Massachusetts.

On September 29, 2016, the Company closed a private placement of common stock, preferred stock and warrants, contemplated by a securities purchase agreement dated September 15, 2016, with certain institutional and accredited investors. The net proceeds after deducting placement agent fees and other transaction-related expenses was $27.6 million. See Note 6, Capital Stock, for further discussion of the private placement.

In January 2018, the Company completed an underwritten registered direct offering of 2,691,494 shares of common stock. The total net proceeds of the offering were $5.7 million after deducting underwriter’s discounts and commissions, and expenses related to the offering.

In March 2018, the Company entered into an equity distribution agreement (“ATM Agreement”) with Canaccord Genuity Inc. (“Canaccord”), pursuant to which the Company may, from time to time, sell shares of its common stock having an aggregate offering price of up to $10.0 million (the “Shares”) through Canaccord, as sales agent. During the nine months ended September 30, 2018, the Company sold an aggregate of 5,766,247 shares of common stock and received $4.0 million after deducting commissions related to the ATM Agreement and other offering costs. From October 1, 2018 through November 6, 2018, the Company sold an aggregate of 867,656 shares of its common stock and received $0.5 million after deducting commissions related to the ATM Agreement.

On October 10, 2018, the Company closed an underwritten public offering of 26,155,000 shares of its common stock and warrants to purchase up to 19,616,250 shares of common stock, at a combined purchase price of $0.65 per share of common stock and accompanying warrant. The gross proceeds from this offering were $17.0 million, before deducting underwriting discounts and commissions, and offering expenses payable by the Company. The warrants are exercisable immediately upon issuance at a price of $0.70 per share of common stock and have a term of five years commencing on the date of issuance.

Since its inception, the Company has devoted substantially all of its efforts to product development, recruiting management and technical staff, raising capital, starting up production and building infrastructure and has not yet generated revenues from its planned principal operations. Expenses have primarily been for research and development and related administrative costs.

The Company is subject to a number of risks. The developmental nature of its activities is such that significant inherent risks exist in the Company’s operations. Principal among these risks are the successful development of therapeutics, ability to obtain adequate financing, obtaining regulatory approval for any of its product candidates in any jurisdiction, obtaining adequate reimbursement rates for any of its approved product candidates, compliance with government regulations, protection of proprietary therapeutics, fluctuations in operating results, dependence on key personnel and collaborative partners, adoption of the Company’s products by the physician community, rapid technological changes inherent in the markets targeted, the introduction of substitute products and competition from larger companies.

Liquidity

The consolidated financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As shown in the accompanying consolidated financial statements, the Company had an accumulated deficit at September 30, 2018 of $216.0 million and has incurred losses and cash flow deficits from operations for the nine months ended September 30, 2018 and 2017. The Company has financed operations to date primarily through public and private placements of equity securities, and borrowings under debt agreements. The Company anticipates that it will continue to incur net losses for the next several years. The Company believes that its existing cash, cash equivalents and marketable securities will only be sufficient to fund its projected cash needs into the middle of 2019. Accordingly, these factors, among others, raise substantial doubt about the Company’s ability to continue as a going concern. The Company will require additional capital to sustain operations through FDA approval of NeoCart and to commercialize NeoCart, if approved. To meet its capital needs, the Company intends to raise additional capital through debt or equity financing or other strategic transactions. However, such financing may not be on favorable terms or available to the Company. The failure of the Company to obtain sufficient funds on commercially acceptable terms when needed will have a material adverse effect on the Company’s business, results of operations and financial condition. The forecast of cash resources is forward-looking information that involves risks and uncertainties, and the actual amount of our expenses could vary materially and adversely as a result of a number of factors. The Company has based its estimates on assumptions that may prove to be wrong, and the Company’s expenses could prove to be significantly higher than it currently anticipates.

Basis of Accounting

The consolidated financial statements are unaudited and have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). However, they do not include all of the information and footnotes required by GAAP for complete financial statements. These interim consolidated financial statements, in the opinion of the Company’s management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended September 30, 2018 and 2017. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2017, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 15, 2018.

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, ProChon and Histogenics Securities Corporation. All significant intercompany accounts and transactions are eliminated in consolidation.