Microsatellite-stable metastatic colorectal cancer (MSS mCRC) has long been considered resistant to immunotherapy — with PD-1 inhibitors alone offering little benefit. A new immunotherapy combination may be changing that paradigm.
In this video, we break down botensilimab plus balstilimab (Bot/Bal), a novel dual-checkpoint strategy designed specifically for immunologically cold tumors. Botensilimab, an Fc-enhanced anti-CTLA-4 antibody, initiates immune activation by reshaping the tumor microenvironment and depleting regulatory T cells. Balstilimab, a fully human anti-PD-1 antibody, sustains T-cell activity and prevents immune exhaustion.
In a phase I study of heavily pretreated MSS metastatic colorectal cancer, this combination achieved a median overall survival of ~21 months, with durable benefit in responders — outperforming historical outcomes seen with regorafenib, trifluridine–tipiracil, fruquintinib, and even the SUNLIGHT regimen, despite limited early PFS.
We also discuss:
• Why OS benefit may matter more than early PFS in immune-reprogramming strategies
• Safety profile and immune-related toxicity management
• Availability through Expanded Access in France
• What to expect from the upcoming Phase III BATTMAN trial
Read the full scientific breakdown and trial analysis on OncoDaily.