Immatics Reports ESMO Data for Two PRAME Programs, Including a 32% Response Rate for IMA402 in Melanoma

Immatics N.V. (NASDAQ: IMTX), a clinical-stage company developing cancer therapies that target the PRAME protein, announced on October 24, 2026 updated clinical data from two of its PRAME programs at the European Society for Medical Oncology (ESMO) 2026 Annual Meeting in Madrid. The results cover IMA402, an off-the-shelf bispecific, and IMA203CD8, a one-time cell therapy, both tested in heavily pretreated patients with advanced solid tumors.

IMA402 Results in PRAME-High Melanoma

As of a June 1, 2026 data cutoff, 126 patients had received at least one infusion of IMA402 in the ongoing Phase 1b trial. Patients had received a median of three prior lines of systemic treatment. The efficacy population included 40 patients treated within the recommended Phase 2 dose range of 10 to 45 mg, and 31 of them had tumors with high PRAME expression.

Across the 40 patients, IMA402 produced a confirmed objective response rate of 25% and a disease control rate of 63%, with the longest ongoing response exceeding two years. In patients with PRAME-high melanoma, the confirmed response rate was 32%, and the median duration of response was 12.5 months. In addition, 91% of those patients were alive at one year, compared with 60% of patients treated below the recommended dose range. All patients with PRAME-high melanoma had previously received immune checkpoint inhibitors.

On safety, the company reported that the most frequent treatment-related side effects were transient lymphopenia and low-grade cytokine release syndrome, with no cases of ICANS, a neurological side effect associated with some immune therapies. According to Immatics, combining IMA402 with a checkpoint inhibitor added no further toxicity.

IMA203CD8 Cell Therapy Across Tumor Types

IMA203CD8 is a T-cell therapy that targets PRAME and requires only a single infusion. As of an August 7, 2026 cutoff, 98 patients had enrolled in its Phase 1 trial, and 90 were evaluable for efficacy, including patients with ovarian and uterine cancer, melanoma and synovial sarcoma.

Across all dose levels and tumor types, the therapy produced a confirmed objective response rate of 41% and a disease control rate of 82%, with some responses ongoing for more than 2.5 years. Among 20 patients with gynecologic cancers treated at clinically relevant doses, the confirmed response rate was 55%, with a median duration of response of 8.4 months after a median follow-up of 6.0 months. In addition, the trial did not reach a maximum tolerated dose at doses up to 12.5 billion cells.

“As the IMA203CD8 PRAME cell therapy data continue to mature, we are increasingly encouraged by its broad potential for patients with advanced PRAME-positive cancers,” said Cedrik Britten, M.D., Ph.D., Chief Medical Officer at Immatics.

Next Steps for the PRAME Pipeline

For IMA402, Immatics plans to pursue combinations with checkpoint inhibitors in melanoma and gynecologic cancers. The company also plans to test IMA402 alongside IMA401, its MAGEA4/8-directed bispecific, in lung cancer, with first data expected in 2027. According to the company, its liquid biopsy-based PRAME test could support patient selection and potential fast-to-market strategies, subject to regulatory approval.

Meanwhile, Phase 1a dose escalation for IMA203CD8 is complete, and Immatics is enrolling patients with uterine cancer at clinically relevant doses. Investigators also plan to start a Phase 1/2 trial in PRAME-positive pediatric cancers in the first half of 2027. Its third PRAME program, the cell therapy anzu-cel, is in the Phase 3 SUPRAME trial in advanced melanoma, and an ESMO poster presented additional exploratory analyses from its Phase 1b melanoma cohort.

Strategic Investment Summary

• ESMO Data: Immatics N.V. (NASDAQ: IMTX) presented updated data for its IMA402 bispecific and IMA203CD8 cell therapy at ESMO 2026 on October 24, 2026.
• IMA402 in Melanoma: PRAME-high melanoma patients showed a 32% confirmed response rate, a 12.5-month median duration of response and 91% survival at one year.
• IMA402 Safety: The most frequent treatment-related side effects were transient lymphopenia and low-grade cytokine release syndrome, with no ICANS reported.
• IMA203CD8 Activity: A single infusion produced a 41% confirmed response rate across tumor types and 55% in gynecologic cancers at clinically relevant doses.
• Upcoming Milestones: Immatics expects first data for IMA402 combined with IMA401 in lung cancer in 2027, while investigators plan a pediatric trial of IMA203CD8 in the first half of 2027.
• Late-Stage Program: Anzu-cel, a third PRAME cell therapy, is in the Phase 3 SUPRAME trial in advanced melanoma.

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