Key Takeaways:
Immatics' PRAME-directed cell therapy shrank tumors in 63% of patients with platinum-resistant ovarian and uterine cancers, offering a potential new option for diseases where standard treatments routinely fail.
"These clinical data in ovarian cancer, uterine cancer and synovial sarcoma, along with previously released data in melanoma, further reinforce our aim to develop IMA203CD8 in PRAME-positive cancers beyond melanoma," Cedrik Britten, chief medical officer at Immatics, said.
Among 19 efficacy-evaluable patients treated at clinically relevant doses, the confirmed objective response rate was 50%, including four complete responses. The longest ongoing response reached 12 months. In a separate cohort of 12 heavily pretreated synovial sarcoma patients, the response rate hit 67% with a 64% confirmed rate, including one complete response ongoing at roughly three years. Tumor reduction occurred in 78% of gynecologic cancer patients and 92% of those with synovial sarcoma.
PRAME is expressed in more than 50 cancer types, giving Immatics a broad addressable market if the therapy continues to perform. The company is expanding evaluation into additional PRAME-positive solid tumors and expects to set the recommended Phase 2 dose later this year. Updated durability data are planned for the second half of 2026.
IMA203CD8 is a one-time infusion engineered to recognize an intracellular PRAME-derived peptide presented by HLA-A*02:01 on cancer cells. The therapy co-transduces CD8αβ alongside the PRAME TCR, adding functional CD4+ T cells designed to boost the anti-tumor response. The approach differs from standard checkpoint inhibitors by directly targeting a cancer-testis antigen expressed across a wide range of solid tumors.
The safety profile was manageable across all 39 treated patients. The most common treatment-emergent adverse events were anticipated cytopenias associated with lymphodepletion. Cytokine release syndrome was mostly low-grade — 44% Grade 1 and 44% Grade 2, with 7% Grade 3. Immune effector cell-associated neurotoxicity syndrome and hemophagocytic lymphohistiocytosis each occurred in 7% of patients. No treatment-related Grade 5 events were reported.
Immatics' PRAME franchise includes three product candidates across two modalities: anzu-cel (IMA203), IMA203CD8, and the IMA402 bispecific. The company is also exploring combinations with immune checkpoint inhibitors and with Moderna's PRAME mRNA designed to enhance cell therapy.
The data were presented at the American Society for Clinical Oncology annual meeting in Chicago. Immatics shares, which trade on the Nasdaq under the ticker IMTX, could see increased interest as the platform demonstrates activity across tumor types with distinct biology and varying PRAME expression levels, including lower levels in ovarian carcinoma. The company has not disclosed its cash position in the release, but with multiple clinical programs and planned expansion into additional indications, the capital runway will be a key metric for investors.
This article is for informational purposes only and does not constitute investment advice.
