Immatics (IMTX) Clinical Data Presentation summary

Mechanism and design of IMA401

• IMA401 is a next-generation bispecific TCER® molecule targeting MAGEA4/8 peptides presented by HLA-A*02, designed for high potency and specificity with minimized cytokine release and optimized dosing schedules.

• The TCER® format demonstrates superior potency and specificity compared to alternative TCR bispecific designs, validated across different TCRs and T cell recruiting antibodies.

• MAGEA4/8 target is presented at over fivefold higher density than commonly used MAGEA4 peptides, with significant prevalence in several solid tumor types.

Clinical trial design and patient characteristics

• Phase 1a dose escalation basket trial enrolled 35 heavily pre-treated patients with recurrent/refractory solid tumors, all HLA-A*02:01 and MAGEA4/8-positive.

• Dose escalation used adaptive BLRM model, with ongoing escalation and no maximum tolerated dose (MTD) reached as of data cut-off.

• Median age was 62–64 years, median prior systemic treatments was 3–4, and most patients had multiple metastatic sites.

Safety and tolerability

• Most frequent treatment-related adverse events were transient lymphopenia (34%), mild to moderate cytokine release syndrome (CRS, 31%), and neutropenia (23%).

• No grade ≥3 CRS observed; neutropenia resolved in all but one case, with one possibly related death due to pneumonia and neutropenia.

• Overall tolerability profile was manageable, supporting continued dose escalation.