SystImmune Presents Promising SCLC Data for EGFR x HER3 ADC

SystImmune has presented preliminary efficacy data from a Phase I clinical trial of izalontamab brengitecan (iza-bren), a bispecific antibody-drug conjugate (ADC) targeting EGFR and HER3, in patients with small cell lung cancer (SCLC). The results were shared at the ASCO 2025 conference.

The trial, which included 58 SCLC patients previously treated, demonstrated notable responses. In patients who had received one prior line of therapy, the confirmed objective response rate (cORR) reached 75.0%, with a median overall survival (mOS) of 15.0 months. Across all patients in the study, the cORR was 44.8%, and the median OS was 12.0 months.

The safety profile of iza-bren was reported as manageable. The most frequent treatment-related adverse events were hematologic, including anemia, leukopenia, and thrombocytopenia. Grade 3 or higher adverse events were primarily hematologic and manageable with supportive care, leading to a 12.1% discontinuation rate. No new safety signals, such as interstitial lung disease, were observed.

SystImmune, in partnership with Bristol Myers Squibb, is continuing to develop izalontamab brengitecan. The company is advancing the compound into Phase III studies to further evaluate its potential as a treatment for SCLC patients, aiming to address an unmet need in this challenging cancer indication.