Nature of Business and Basis of Presentation	12 Months Ended
Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	(1) Nature of Business and Basis of Presentation Organization Cullinan Oncology, Inc., together with its consolidated subsidiaries (Cullinan or the Company), is a biopharmaceutical company developing a diversified pipeline of targeted oncology therapies for cancer patients. Cullinan’s predecessor company, Cullinan Pharmaceuticals, LLC was formed in September 2016 and was subsequently renamed Cullinan Oncology, LLC (the LLC) in November 2017. The LLC’s wholly-owned subsidiary, Cullinan Management, Inc. (Management), was formed in September 2016 and became the surviving entity in a reverse merger with the LLC in January 2021. In February 2021, the Company changed its name from Cullinan Management, Inc. to Cullinan Oncology, Inc. As of December 31, 2021, the Company had four development subsidiaries, or Asset Subsidiaries: Cullinan Amber Corp. (Amber), Cullinan Florentine Corp. (Florentine), Cullinan MICA Corp. (MICA) and Cullinan Pearl Corp. (Pearl). As of December 31, 2020, the LLC had five development subsidiaries: Amber, Cullinan Apollo Corp. (Apollo), Florentine, MICA and Pearl. Apollo was dissolved in August 2021. Reorganization, Reverse Stock Split and Initial Public Offering In January 2021, the Company completed its initial public offering (IPO) in which it issued and sold 13,685,000 shares of its common stock, including 1,785,000 shares sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $21.00 per share. The shares began trading on the Nasdaq Global Select Market on January 8, 2021 under the symbol “CGEM”. The net proceeds received by the Company from the offering were $264.5 million, after deducting underwriting discounts, commissions and other offering expenses. Immediately prior to the effectiveness of the Company’s registration statement, the Company completed its reorganization, whereby the LLC merged with and into Management and Management was the surviving entity. Management was the registrant in the IPO. Pursuant to the Reorganization, all outstanding Redeemable Preferred Units, Non-Voting Incentive Units and common units converted into shares of Management common stock while common unit options were exchanged for stock options. Immediately following the Reorganization, the Company effected a one-for-7.0390 reverse stock split of its issued and outstanding shares of common stock (the Reverse Stock Split). Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements prior to the Reorganization and notes thereto have been adjusted retroactively, where applicable, to reflect the effect of the Reorganization and Reverse Stock Split. Refer to Note 3 for additional details relating to the Reorganization and Reverse Stock Split. Liquidity The Company has incurred operating losses and negative cash flows from operations since its inception and expects to continue to generate operating losses for the foreseeable future. The Company’s ultimate success depends on the outcome of its research and development activities as well as the ability to commercialize the Company’s product candidates. The Company is subject to a number of risks including, but not limited to, the need to obtain adequate additional funding for the ongoing and planned clinical development of its product candidates. Due to the numerous risks and uncertainties associated with pharmaceutical products and development, the Company is unable to accurately predict the timing or amount of funds required to complete development of its product candidates, and costs could exceed the Company’s expectations for a number of reasons, including reasons beyond the Company’s control. The Company has incurred losses since inception and has an accumulated deficit of $158.9 million as of December 31, 2021. Since inception, the Company has funded its operations primarily through the sale of equity securities. The Company expects that its cash, cash equivalents and short-term investments of $290.5 million and long-term investments of $140.4 million as of December 31, 2021, will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next twelve months from the date of issuance of these consolidated financial statements.

Nature of Business and Basis of Presentation

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Business and Basis of Presentation

(1)

Nature of Business and Basis of Presentation

Organization

Cullinan Oncology, Inc., together with its consolidated subsidiaries (Cullinan or the Company), is a biopharmaceutical company developing a diversified pipeline of targeted oncology therapies for cancer patients. Cullinan’s predecessor company, Cullinan Pharmaceuticals, LLC was formed in September 2016 and was subsequently renamed Cullinan Oncology, LLC (the LLC) in November 2017. The LLC’s wholly-owned subsidiary, Cullinan Management, Inc. (Management), was formed in September 2016 and became the surviving entity in a reverse merger with the LLC in January 2021. In February 2021, the Company changed its name from Cullinan Management, Inc. to Cullinan Oncology, Inc.

As of December 31, 2021, the Company had four development subsidiaries, or Asset Subsidiaries: Cullinan Amber Corp. (Amber), Cullinan Florentine Corp. (Florentine), Cullinan MICA Corp. (MICA) and Cullinan Pearl Corp. (Pearl). As of December 31, 2020, the LLC had five development subsidiaries: Amber, Cullinan Apollo Corp. (Apollo), Florentine, MICA and Pearl. Apollo was dissolved in August 2021.

Reorganization, Reverse Stock Split and Initial Public Offering

In January 2021, the Company completed its initial public offering (IPO) in which it issued and sold 13,685,000 shares of its common stock, including 1,785,000 shares sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $21.00 per share. The shares began trading on the Nasdaq Global Select Market on January 8, 2021 under the symbol “CGEM”. The net proceeds received by the Company from the offering were $264.5 million, after deducting underwriting discounts, commissions and other offering expenses.

Immediately prior to the effectiveness of the Company’s registration statement, the Company completed its reorganization, whereby the LLC merged with and into Management and Management was the surviving entity. Management was the registrant in the IPO. Pursuant to the Reorganization, all outstanding Redeemable Preferred Units, Non-Voting Incentive Units and common units converted into shares of Management common stock while common unit options were exchanged for stock options. Immediately following the Reorganization, the Company effected a one-for-7.0390 reverse stock split of its issued and outstanding shares of common stock (the Reverse Stock Split).

Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements prior to the Reorganization and notes thereto have been adjusted retroactively, where applicable, to reflect the effect of the Reorganization and Reverse Stock Split. Refer to Note 3 for additional details relating to the Reorganization and Reverse Stock Split.

Liquidity

The Company has incurred operating losses and negative cash flows from operations since its inception and expects to continue to generate operating losses for the foreseeable future. The Company’s ultimate success depends on the outcome of its research and development activities as well as the ability to commercialize the Company’s product candidates. The Company is subject to a number of risks including, but not limited to, the need to obtain adequate additional funding for the ongoing and planned clinical development of its product candidates. Due to the numerous risks and uncertainties associated with pharmaceutical products and development, the Company is unable to accurately predict the timing or amount of funds required to complete development of its product candidates, and costs could exceed the Company’s expectations for a number of reasons, including reasons beyond the Company’s control. The Company has incurred losses since inception and has an accumulated deficit of $158.9 million as of December 31, 2021.

Since inception, the Company has funded its operations primarily through the sale of equity securities. The Company expects that its cash, cash equivalents and short-term investments of $290.5 million and long-term investments of $140.4 million as of December 31, 2021, will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next twelve months from the date of issuance of these consolidated financial statements.