Background	6 Months Ended
Background	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background	Background Carisma Therapeutics Inc., a Delaware Corporation (collectively with its subsidiaries, the Company), is a clinical-stage cell therapy company focused on utilizing the Company’s proprietary macrophage and monocyte cell engineering platform to develop transformative immunotherapies to treat cancer and other serious diseases. The Company has created a comprehensive cell therapy platform to enable the therapeutic use of engineered macrophages and monocytes, which belong to a subgroup of white blood cells called myeloid cells. The Company’s initial focus is its proprietary Chimeric Antigen Receptor Macrophage (CAR-M) cell therapy platform, which redirects macrophages against specific tumor associated antigens and enables targeted anti-tumor immunity by utilizing genetically modifying myeloid cells (macrophages and monocytes) to express chimeric antigen receptors (CARs), enabling the potent innate immune cells to recognize specific tumor-associated antigens on the surface of tumor cells. The Company’s initial product candidates, CT-0508 and CT-0525 are ex vivo autologous cell therapy product candidates, wherein immune cells from blood drawn from a patient are engineered outside of the body and reinfused into the same patient. The Company also has research programs to develop allogeneic and in vivo cell therapy macrophage products. The Company’s lead product candidate, CT-0508, is the first CAR-M to be evaluated in a human clinical trial and is intended to treat solid tumors that overexpress HER2, a protein that is overexpressed on the surface of a variety of solid tumors, including breast cancer, gastric cancer, esophageal cancer, salivary gland cancer, and numerous others. It has been granted “Fast Track” status for the treatment of patients with HER2 overexpressing solid tumors by the United States Food and Drug Administration (FDA). CT-0508 is currently being studied in a multi-center open label Phase 1 clinical trial in the United States (U.S.). This ongoing first-in-human study evaluates the safety, tolerability and manufacturing feasibility of CT-0508 along with several customary exploratory secondary endpoints. The Company has completed enrollment of the first group of patients in this trial, with nine patients having been successfully dosed over a five-day dosing schedule. In November 2022, the Company presented preliminary clinical results from the first group of patients. CT-0508 was successfully manufactured using macrophages obtained from heavily pre-treated, advanced solid tumor patients and has shown high CAR expression, viability, and purity. In addition, CT-0508 has been generally well-tolerated after infusion with no dose-limiting toxicities reported to date from the nine patients enrolled in the first group. While the results from this early clinical trial data are both preliminary and limited, the Company believes the results indicate that CT-0508 can be detected within the tumor microenvironment (TME), lead to remodeling and activation of the TME, and potentially induce anti-tumor adaptive immunity. In addition to the first group of patients in this study, the Company initiated a second group to evaluate bolus dosing of patients with data anticipated from this group in the second half of 2023. The Company has also initiated several additional sub-studies evaluating CT-0508 in the clinical setting. In addition to monotherapy treatment, the Company has observed synergistic potential of CT-0508 with a PD1 blocking T-cell checkpoint inhibitor in multiple pre-clinical models. As a result of those studies and the preliminary results from group 1 in the Company’s clinical trial, the Company initiated a sub-study to evaluate at least nine patients with the co-administration of CT-0508 and pembrolizumab in the first half of 2023. The Company anticipates the initial data from this sub-study in the second half of 2023. The Company's second product candidate, CT-0525, which also is intended to treat solid tumors that overexpress HER2, is in pre-clinical development and utilizes a novel approach to CAR-M therapy that engineers patients’ monocytes directly, without ex vivo differentiation into macrophages, as the Company currently does for CT-0508. The Company refers to this CAR-Monocyte approach as CAR-Mono. This process enables a single day manufacturing process, enables the ability to manufacture up to ten billion cells from a single apheresis, and leverages an automated, closed-system manufacturing process. In addition, CAR-Mono has the potential to improve upon the potential anti-tumor effect of a CAR-Macrophage. By increasing the cell yield, the CAR-Mono approach enables a larger dose than a CAR-Macrophage. In addition, CT-0525 has the potential for improved persistence and trafficking, all observed pre-clinically. The increased cell yield and the improved persistence and trafficking may improve tumor control. The Company expects to submit an Investigational New Drug Application (IND) to the FDA for CT-0525 in the second half of 2023, initiate clinical development shortly thereafter, and treat the Company's first patient in the first half of 2024. Beyond CT-0508 and CT-0525, the Company has a broad pipeline of cell therapy assets in various stages of pre-clinical development. In addition to the development of ex vivo CAR-M cell therapies, the Company is developing in vivo CAR-M gene therapies, wherein immune cells are directly engineered within the patient’s body. To advance the Company’s in vivo CAR-M therapeutics, the Company established a strategic collaboration with ModernaTX Inc. (Moderna) (Note 10). Reverse Merger with Sesen Bio On March 7, 2023, the Company (formerly publicly-held Sesen Bio, Inc.) consummated a merger with CTx Operations, Inc. (formerly privately-held CARISMA Therapeutics Inc.) (Legacy Carisma) pursuant to an Agreement and Plan of Merger and Reorganization, as amended (the Merger Agreement), by and among the Company, Legacy Carisma and Seahawk Merger Sub, Inc. (Merger Sub), a Delaware corporation and wholly-owned subsidiary of the Company. The Merger Agreement provided for the merger of Merger Sub with and into Legacy Carisma, with Legacy Carisma continuing as a wholly-owned subsidiary of the Company and the surviving corporation of the merger (the Merger). Pursuant to the Merger Agreement, the Company changed its name from “Sesen Bio, Inc.” to “Carisma Therapeutics Inc.” At the closing of the Merger, (a) each then outstanding share of Legacy Carisma common stock and convertible preferred stock (including shares of Legacy Carisma common stock issued in connection with the pre-closing financing transaction described below) were converted into shares of Sesen Bio common stock at an exchange ratio of 1.8994 shares of Sesen Bio for each share of Legacy Carisma (the Exchange Ratio), and (b) each then outstanding stock option to purchase Legacy Carisma common stock was assumed by Sesen Bio, with necessary adjustments to reflect the Exchange Ratio. Except as otherwise indicated, references herein to “Carisma,” the “Company,” or the “Combined Company,” refer to Carisma Therapeutics Inc. on a post-Merger basis, and references to “Legacy Carisma” refer to the business of privately-held CARISMA Therapeutics Inc. prior to the completion of the Merger. References to “Sesen Bio” refer to Sesen Bio, Inc. prior to the completion of the Merger. Following the Merger, the shareholders of Legacy Carisma held 74.2% of the Combined Company and the shareholders of Sesen Bio held 25.8% of the Combined Company. Basis of Presentation and Exchange Ratio As discussed in Note 3, the Merger was accounted for as reverse capitalization under which the historical financial statements of the Company prior to the Merger are Legacy Carisma. All common stock, per share and related information presented in the consolidated financial statements and notes prior to the Merger has been retroactively adjusted to reflect the Exchange Ratio.