In an ongoing, phase 2a, multiple basket study (MyPathway), 57 treatment-refractory metastatic colorectal cancer patients harboring HER2 amplification were enrolled and have then received pertuzumab plus trastuzumab as next-line treatment. The results showed that one patient (1.8%) had a complete response and 17 (29.8%) had partial responses. The median duration of response (DoR) was 5.9 months, median progression-free survival (PFS) was 2.9 months, and median overall survival (OS) was 11.5 months. Moreover, the therapeutic effects were significantly better in KRAS wild-type than in KRAS mutant (ORR: 39.5% vs. 7.7%; mPFS: 14.0 vs. 8.5 months). The above results suggested that the combination of pertuzumab and trastuzumab is a new therapeutic option for patients with heavily pretreated, HER2-amplified metastatic colorectal cancer, especially for those with KRAS wild-type tumors.
Lancet Oncol. 2019 Apr;20(4):518-530.