IGM Biosciences, Inc. announced an update on its clinical development program for IGM-8444, a novel multivalent DR5 agonist, and announced plans for a new randomized combination trial in patients with metastatic colorectal cancer. Initial Phase 1 data reported from a cohort of patients with combination treatment of IGM-8444 and FOLFIRI showed an encouraging safety profile which was broadly comparable to that expected from chemotherapy alone in this setting. Specifically, there was no drug related clinically significant hepatotoxicity, with only grade 1 and grade 2 transient liver enzyme elevations observed.

In patients with metastatic colorectal cancer, the combination of IGM-8444 and FOLFIRI showed promising activity, with multiple confirmed responses observed even in patients who had previously progressed on FOLFIRI. In 13 metastatic patients treated with doses of IGM-8444 from 1 to 10 mg/kg plus standard doses of FOLFIRI chemotherapy, there were four responses observed (three confirmed at 3mg/kg), and one additional patient had substantial tumor shrinkage allowing for subsequent complete surgical resection. Responses occurred in patients with KRAS wild type and mutated tumors and in patients with or without liver metastases.

The majority of patients were on their third line of treatment or beyond and 10 of the 13 patients had previously been treated with FOLFIRI chemotherapy. Median progression free survival (PFS) among nine 3L+ patients was 5.5 months, with the longest observed PFS extending beyond 12 months.