Tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresctable or metastatic colorectal cancer: multinational phase 2 trial

The multinational phase 2 MOUNTAINEER trial evaluated tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer. At a median duration of follow-up of 20.7 months, the blinded independent centrally reviewed ORR and DCR were 38.1% and 71.4%, respectively. The median duration of response was 12.4 months, the median progression-free survival was 8.2 months, and the median overall survival was 24.1 months. The combination was well tolerated. Diarrhea was predominantly low-grade and manageable. The authors conclude that in this patient group tucatinib plus trastuzumab had clinically meaningful anti-tumor activity and favorable tolerability.