ASCO: Immatics posts data on PRAME pipeline ahead of pivotal readout
Immatics has published a series of updates on its PRAME pipeline, using the American Society for Clinical Oncology (ASCO) Annual Meeting to share data on its lead candidate and next-generation program.
The biotech, which has a presence in Germany and Texas, has built a pipeline on preferentially expressed antigen in melanoma (PRAME). The cancer-testis antigen is broadly expressed in solid tumors, providing Immatics with chances to treat a range of diseases including cutaneous melanoma, uterine carcinoma and synovial sarcoma.
Immatics arrived at this year’s ASCO with data on two PRAME programs, including its next-generation cell therapy IMA203CD8. The biotech’s lead cell therapy, anzu-cel, is scheduled to deliver Phase III data this year but only addresses markets with about 9,000 patients annually. IMA203CD8 is Immatics’ effort to expand into all advanced PRAME cancers, increasing the target population to 75,000 patients a year.
In a Phase I trial, Immatics saw responses in 12 of 19 gynecologic cancer patients who received one infusion of a clinically relevant dose of IMA203CD8. Four responses were complete, although only two of those were confirmed. As of the data cutoff, eight of the nine confirmed responses were ongoing, with the longest response continuing 12 months after treatment.
The tolerability profile was predictable and manageable, Antonia Busse, a physician at Charite Medical University Hospital, said in the ASCO presentation. Immatics saw cytokine release syndrome, an inflammatory response associated with immunotherapies, in 96% of patients, but most of the cases were Grade I or II. There were two dose-limiting toxicities — one case of immune effector cell-associated neurotoxicity syndrome and one skin infection — in the 27 patients in the safety and tolerability cohort.
Other researchers presented data on Immatics’ first-generation PRAME cell therapy, anzu-cel. The data included patient-level clinical response dynamics in patients with advanced melanoma. More than 40% of the patients in the dataset had cutaneous melanoma, the condition targeted in the Phase III anzu-cel trial that is scheduled to report data this year.
An exploratory analysis showed disease progression on anzu-cel was frequently driven by new lesions, progression of non-target lesions or selective outgrowth of individual target lesions. Many target lesions remained controlled at the time of disease progression. The analysis supports the idea that anzu-cel can sustain disease control across multiple metastatic sites, Immatics said. The biotech also shared data on its two PRAME cell therapies in synovial sarcoma.
Beyond PRAME
Anzu-cel, IMA203CD8 and a third PRAME program, the bispecific IMA402, form the core of Immatics’ pipeline. Beyond PRAME, Immatics is developing IMA401, a MAGEA4/8-targeted T-cell receptor-based bispecific.
The biotech shared first-in-human data on IMA401 at ASCO, reporting a manageable tolerability profile and early evidence of efficacy as a monotherapy and in combination with Merck’s Keytruda. Based on the data, Immatics plans to test IMA401 in combination with its PRAME-directed bispecific IMA402.
