Immatics: Immatics heads to Phase 3 with melanoma cell therapy, seeks to raise $150M

Immatics said its PRAME-targeted T cell therapy shrank tumors by at least 30% in just over half of melanoma patients in an early-stage trial, and the company plans to start a pivotal study by the end of this year. In 26 melanoma patients enrolled in Immatics' Phase 1b study, 14 had a confirmed response to its T cell receptor-based therapy - seven of those responses are ongoing. The median progression-free survival was six months, while the median overall survival was not reached, Immatics reported on Thursday. In a statement, Immatics CMO Cedrik Britten said the results and a meeting with the FDA "[position] us to advance the development of IMA203 in the second-line or later metastatic melanoma setting." Immatics also announced that it is seeking $150 million via a stock sale. The company's shares $IMTX were down 11% on Thursday. Immatics is developing IMA203 for patients with a cell marker called HLA-A*02. (HLA types are often used in transplants to determine a match between donor and recipient.) Immatics takes a patients' own cells and engineers the cell therapy to express T cell receptors against PRAME, which is highly expressed in melanomas. Patients were given lymphodepleting chemotherapy and low-dose IL-2 along with the TCR cell therapy. On safety, there were eight cases of grade 3 or higher cytokine release syndrome and three grade 3 or higher ICANS - two serious conditions associated with immunotherapies. Immatics said that it is planning to start a Phase 3 study called SUPRAME in December to test IMA203 in second-line or later melanoma patients whose cancers have metastasized or can't be removed by surgery. Earlier this year, Iovance won approval for its tumor-infiltrating lymphocyte-based cell therapy in advanced melanoma, which it markets as Amtagvi. Immatics, as well as Immunocore, are also developing bispecific antibodies targeted at PRAME.