Die folgenden Informationen liegen ausschließlich in englischer Sprache vor. 

The data from the ongoing Phase 1a trial will be presented today at the European Society for Medical Oncology (ESMO) Immuno-Oncology Congress 2025 during a Mini Oral Presentation by Prof. Dr. med. Antonia Busse, Charité, Berlin, Germany. The slides are accessible in the ‘Events & Presentations’ section of the Investors & Media section of the Company’s website.

“The patients enrolled in this trial were heavily pretreated and presented with various challenging cases of solid tumors expressing PRAME,” said Antonia Busse, M.D. “It is encouraging to be able to offer these patients a one-time treatment that is tolerable with a durable clinical benefit, as shown in this dose escalation trial. These early results underscore the multi-indication targeting potential of IMA203CD8 in patients with PRAME-expressing solid tumors.”

“IMA203CD8, our second-generation PRAME cell therapy, marks another wave of innovation in our PRAME franchise,” said Cedrik Britten, M.D., Chief Medical Officer at Immatics. “Our vision is to leverage its tumor-agnostic potential and bring meaningful benefit to patients with advanced PRAME cancers beyond melanoma. The data from the ongoing dose escalation, including the initial proof-of-concept in patients with ovarian carcinoma, reinforce the promise of IMA203CD8 as a monotherapy for difficult-to-treat indications. We look forward to completing dose escalation for IMA203CD8 and upcoming clinical readouts of more patients treated at the two highest dose levels.”

IMA203CD8 PRAME Cell Therapy (GEN2) Phase 1a Dose Escalation Data Summary

Patient Population: Heavily pre-treated patient population with limited treatment options

As of the data cutoff on October 27, 2025, 78¹ heavily pre-treated patients (median of three prior systemic treatments) with advanced and/or metastatic solid tumors expressing PRAME were enrolled in the ongoing Phase 1a dose escalation clinical trial (NCT03686124). The median total infused dose across seven escalating dose levels was 1.6x10⁹ TCR T cells (range 0.4-12.5x10⁹ TCR T cells). The efficacy-evaluable² patient population included 69 patients: 42 with melanoma, 11 with ovarian carcinoma, 11 with synovial sarcoma and 5 with other tumor types³.

Safety: Treatment with IMA203CD8 showed manageable tolerability

IMA203CD8 showed manageable tolerability in the 78 patients enrolled. The most frequent treatment-emergent adverse events (AE) were anticipated cytopenias associated with lymphodepletion. Expected and manageable cytokine release syndrome (CRS) was mostly Grade 1 to 2 and was consistent with the mechanism of action: Grade 1: 35%, Grade 2: 50%, Grade 3: 9%, Grade 4: 1%. Immune effector cell-associated neurotoxicity syndrome (ICANS) and hemophagocytic lymphohistiocytosis (HLH) were infrequently observed. No IMA203CD8-related Grade 5 events occurred.

Based on the manageable tolerability profile, dose escalation is ongoing at dose level 7 (range ~7.2-10x10⁹ TCR T cells) and on track to determine the recommended Phase 2 dose (RP2D).

Anti-tumor Activity and Durability: Deep and durable objective responses in PRAME-positive advanced solid tumors during ongoing dose escalation

A one-time infusion of IMA203CD8 PRAME cell therapy showed promising initial anti-tumor activity during dose escalation across various PRAME-expressing indications at a low median dose of 1.6x10⁹ total IMA203CD8 TCR T cells:

• Confirmed Objective Response Rate (cORR): 36% (23/64)
• Objective Response Rate (ORR): 46% (32/69)
• Tumor reduction: 78% (54/69)
• Disease Control Rate (DCR) at week 6: 84% (58/69)
• Median Duration of Response (mDOR): 9.2 months at a median follow-up (mFU) of 14 months