Immatics reports PRAME bispecific and cell therapy data at ESMO 2026

Immatics presented Phase 1 data for IMA402 and IMA203CD8 at ESMO, with response rates up to 55% in heavily pretreated solid tumour patients.

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Immatics has presented updated clinical data from two PRAME-targeted programmes at the 2026 ESMO Annual Meeting in Madrid, reporting anti-tumour activity across multiple solid tumour types for both its IMA402 TCR bispecific and its IMA203CD8 cell therapy.

The data, drawn from ongoing Phase 1 and Phase 1b studies, represent the most comprehensive public readout yet for Immatics' PRAME franchise, which the Houston- and Tübingen-based company describes as the broadest clinical PRAME targeting effort across any single organisation.

IMA402 bispecific: melanoma results lead

In the Phase 1b trial of IMA402, 126 heavily pretreated patients across multiple tumour types received at least one infusion as of the 1 June 2026 data cutoff. Within the recommended Phase 2 dose range and among the 31 patients with high PRAME expression, IMA402 achieved a confirmed objective response rate of 32% across all indications. In the PRAME-high melanoma subset specifically, the confirmed ORR was also 32%, with a median duration of response of 12.5 months and a one-year overall survival rate of 91%. All melanoma patients in this cohort had received prior immune checkpoint inhibitor therapy, with a median of two prior ICI regimens.

The safety profile was described as favourable, with the most frequent treatment-related adverse events being transient lymphopenia and low-grade cytokine release syndrome. No grade 5 events related to IMA402 were reported, and no cases of immune effector cell-associated neurotoxicity syndrome were observed. Tolerability was consistent whether IMA402 was given as monotherapy or in combination with a checkpoint inhibitor.

Chief Medical Officer Cedrik Britten said the data "reinforce our strategy as we continue to advance IMA402 across multiple cancer types and treatment lines, with combination approaches further expanding its reach."

Next steps for IMA402 include combination studies with ICIs in melanoma and gynaecologic cancers and a planned combination with Immatics' MAGEA4/8-directed bispecific IMA401 in lung cancer, with first data expected in 2027.

IMA203CD8 cell therapy: gynaecologic cancer cohort highlighted

In the IMA203CD8 Phase 1 trial, 90 patients were evaluable for efficacy across tumour types including ovarian cancer, uterine cancer, melanoma and synovial sarcoma, as of the 7 August 2026 cutoff. A single infusion of IMA203CD8 produced an overall ORR of 51% across all dose levels and tumour types, with 83% of patients with evaluable lesions experiencing some degree of tumour reduction.

In the gynaecologic cancer subset treated at clinically relevant doses, the confirmed ORR was 55% and median duration of response was 8.4 months, with overall survival not yet reached at a median follow-up of 7.8 months. The maximum tolerated dose was not reached at doses up to 12.5 billion cells. Immatics is now enrolling uterine cancer patients at selected doses and plans an investigator-initiated Phase 1/2 trial in PRAME-positive paediatric cancers from the first half of 2027.

Competitive and regulatory context

PRAME has attracted significant interest as a tumour-associated antigen given its expression across more than 50 cancer types, offering a potential route to tumour-agnostic treatments. Immatics sits alongside a small number of other companies pursuing TCR-based therapies directed at intracellular targets, a space that has faced historically high attrition compared with antibody-based approaches. The IMA203CD8 and IMA402 datasets are early-stage and subject to the usual caveats of Phase 1 readouts, including small evaluable populations and immature follow-up, but the durability signals observed are notable in heavily pretreated patients.

A registration-enabling Phase 3 trial, called SUPRAME, is already underway for anzu-cel, Immatics' first-generation PRAME cell therapy, in advanced melanoma after checkpoint inhibitor progression. The outcome of that trial will carry significant read-across implications for the broader PRAME franchise and inform regulatory strategy for IMA203CD8 and IMA402 in later-line and combination settings.

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