Immatics is advancing its PRAME-targeted T cell therapy, IMA203, into a Phase 3 trial after promising early-stage results in melanoma patients. The company reported that IMA203 induced tumor shrinkage of at least 30% in just over half of the melanoma patients enrolled in its Phase 1b study.
Phase 1b Trial Results
The Phase 1b study included 26 melanoma patients, of whom 14 experienced a confirmed response to the T cell receptor-based therapy. Seven of these responses are ongoing. The median progression-free survival (PFS) was six months. The median overall survival (OS) was not reached at the time of the report, according to Immatics.
Cedrik Britten, Immatics' CMO, stated that the results, combined with discussions with the FDA, "position us to advance the development of IMA203 in the second-line or later metastatic melanoma setting."
Upcoming Phase 3 Trial and Financial Strategy
Immatics plans to initiate a Phase 3 study, named SUPRAME, in December. This trial will evaluate IMA203 in second-line or later melanoma patients whose cancers have metastasized or cannot be surgically removed. To support these clinical advancements, Immatics is seeking $150 million through a stock sale.
About IMA203
IMA203 is being developed for patients with the HLA-A*02 cell marker. The therapy involves engineering a patient's own cells to express T cell receptors against PRAME (PReferentially expressed Antigen in MElanoma), a protein highly expressed in melanomas. Patients receive lymphodepleting chemotherapy and low-dose IL-2 in conjunction with the TCR cell therapy.
Safety Profile
The Phase 1b trial reported eight cases of grade 3 or higher cytokine release syndrome (CRS) and three cases of grade 3 or higher immune effector cell-associated neurotoxicity syndrome (ICANS), both serious conditions associated with immunotherapies.
Competitive Landscape
Earlier this year, Iovance Biotherapeutics received FDA approval for Amtagvi, a tumor-infiltrating lymphocyte-based cell therapy for advanced melanoma. Immatics, along with Immunocore, is also developing bispecific antibodies targeting PRAME.
