Nature of the Business and Basis of Presentation	6 Months Ended
Jun. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	Note 1. Nature of the business and basis of presentation C4 Therapeutics, Inc., or, together with its subsidiary, the Company, is a clinical-stage biopharmaceutical company focused on harnessing the body’s natural regulation of protein levels to develop novel therapeutic candidates to target and eliminate disease-causing proteins for the treatment of cancer and other diseases. The Company was incorporated in Delaware on October 7, 2015 and has its principal office in Watertown, Massachusetts. Liquidity and capital resources Since its inception, the Company’s primary activities have been focused on research and development activities, building the Company’s intellectual property, recruiting personnel and raising capital to support these activities. To date, the Company has funded its operations primarily with proceeds received from the sales of redeemable convertible preferred stock, sales of common stock through an initial public offering, through its collaboration agreements, and debt financing. The Company has incurred recurring losses since its inception, including net losses of $43.6 million and $22.7 million for the six months ended June 30, 2021 and 2020, respectively. In addition, as of June 30, 2021, the Company had an accumulated deficit of $227.4 million. To date, the Company has not generated any revenue from product sales as none of its product candidates has been approved for commercialization. The Company expects to continue to generate operating losses for the foreseeable future. As further discussed in Note 10, Stockholders’ equity, on October 6, 2020, the Company completed its initial public offering, or the IPO. The net proceeds to the Company were $191.2 million, after deducting underwriting discounts and commissions, and expenses. Upon the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted into 30,355,379 shares of common stock. Also as discussed in more detail in Note 10, Stockholders’ equity, in June 2021, the Company completed a follow-on offering. The net proceeds to the Company were $169.5 million, after deducting underwriting discounts and commissions, and estimated expenses. The Company expects that its cash, cash equivalents and marketable securities of $498.7 million as of June 30, 2021 will be sufficient to fund its operations for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. Accordingly, the condensed consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business. Reverse stock split On September 25, 2020, the Company effected a one-for-8.4335 reverse stock split of its issued and then outstanding common stock and stock options, and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. Accordingly, all issued and then outstanding common stock, options to purchase common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented. Risks and uncertainties The Company is subject to risks common to other life science companies in the early development stage including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing and compliance with the Food and Drug Administration, and other government regulations. If the Company does not successfully advance its programs into and through human clinical trials and commercialize any of its product candidates, the Company may be unable to produce product revenue or achieve profitability. Additionally, if the Company elects to enter into collaborations for its programs, the success of those collaborations may significantly impact its revenue and profitability. There can be no assurance that the Company’s research and development efforts will be successful, adequate protection for the Company’s intellectual property will be obtained, any products developed will obtain or maintain necessary government regulatory approval, or any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in science and technology and substantial competition from pharmaceutical and biotechnology companies. 7 COVID-19 pandemic The impact of the coronavirus, or COVID-19, pandemic on the Company’s business, results of operations and financial condition continues to remain uncertain and will depend on future developments, including the impact of vaccines and new variant strains of COVID-19, and any governmental advisories and restrictions.

Nature of the Business and Basis of Presentation

6 Months Ended

Jun. 30, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of the Business and Basis of Presentation

Note 1. Nature of the business and basis of presentation

C4 Therapeutics, Inc., or, together with its subsidiary, the Company, is a clinical-stage biopharmaceutical company focused on harnessing the body’s natural regulation of protein levels to develop novel therapeutic candidates to target and eliminate disease-causing proteins for the treatment of cancer and other diseases. The Company was incorporated in Delaware on October 7, 2015 and has its principal office in Watertown, Massachusetts.

Liquidity and capital resources

Since its inception, the Company’s primary activities have been focused on research and development activities, building the Company’s intellectual property, recruiting personnel and raising capital to support these activities. To date, the Company has funded its operations primarily with proceeds received from the sales of redeemable convertible preferred stock, sales of common stock through an initial public offering, through its collaboration agreements, and debt financing.

The Company has incurred recurring losses since its inception, including net losses of $43.6 million and $22.7 million for the six months ended June 30, 2021 and 2020, respectively. In addition, as of June 30, 2021, the Company had an accumulated deficit of $227.4 million. To date, the Company has not generated any revenue from product sales as none of its product candidates has been approved for commercialization. The Company expects to continue to generate operating losses for the foreseeable future.

As further discussed in Note 10, Stockholders’ equity, on October 6, 2020, the Company completed its initial public offering, or the IPO. The net proceeds to the Company were $191.2 million, after deducting underwriting discounts and commissions, and expenses. Upon the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted into 30,355,379 shares of common stock.

Also as discussed in more detail in Note 10, Stockholders’ equity, in June 2021, the Company completed a follow-on offering. The net proceeds to the Company were $169.5 million, after deducting underwriting discounts and commissions, and estimated expenses.

The Company expects that its cash, cash equivalents and marketable securities of $498.7 million as of June 30, 2021 will be sufficient to fund its operations for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. Accordingly, the condensed consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

Reverse stock split

On September 25, 2020, the Company effected a one-for-8.4335 reverse stock split of its issued and then outstanding common stock and stock options, and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. Accordingly, all issued and then outstanding common stock, options to purchase common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented.

Risks and uncertainties

The Company is subject to risks common to other life science companies in the early development stage including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing and compliance with the Food and Drug Administration, and other government regulations. If the Company does not successfully advance its programs into and through human clinical trials and commercialize any of its product candidates, the Company may be unable to produce product revenue or achieve profitability. Additionally, if the Company elects to enter into collaborations for its programs, the success of those collaborations may significantly impact its revenue and profitability. There can be no assurance that the Company’s research and development efforts will be successful, adequate protection for the Company’s intellectual property will be obtained, any products developed will obtain or maintain necessary government regulatory approval, or any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in science and technology and substantial competition from pharmaceutical and biotechnology companies.

COVID-19 pandemic

The impact of the coronavirus, or COVID-19, pandemic on the Company’s business, results of operations and financial condition continues to remain uncertain and will depend on future developments, including the impact of vaccines and new variant strains of COVID-19, and any governmental advisories and restrictions.