Meric-Bernstam F, et al. - In patients with HER2-amplified metastatic colorectal cancer, the activity of pertuzumab and trastuzumab was investigated in MyPathway, which is an ongoing, phase 2a, multiple basket study. Patients were able to tolerate dual HER2-targeted therapy with pertuzumab plus trastuzumab. Based on the findings, this therapy could afford a therapeutic option for patients with heavily pretreated, HER2-amplified metastatic colorectal cancer.

Methods

• In this subset analysis, researchers examined patients aged 18 years or older enrolled from 25 hospitals or clinics in 16 states of the US and included those with treatment-refractory, histologically confirmed HER2-amplified metastatic colorectal cancer with measurable or evaluable disease and an Eastern Cooperative Oncology Group performance status score of 2 or less.
• They administered pertuzumab (840 mg loading dose, then 420 mg every 3 weeks, intravenously) and trastuzumab (8 mg/kg loading dose, then 6 mg/kg every 3 weeks, intravenously) to the participants.
• Based on investigator-reported tumor responses, the proportion of patients achieving an objective response was assessed as primary endpoint.

Results

• As of August 1, 2017, among 57 evaluable patients, complete response and partial responses were seen in one (2%) patient and among 17 (30%) patients, respectively; an objective response was achieved by 18 of 57 patients (32%, 95% CI 20–45).
• Diarrhea (19 [33%] of 57 patients), fatigue (18 [32%] patients), and nausea (17 [30%] patients) were documented as treatment-emergent adverse events that were most commonly experienced.
• Overall 21 (37%) of 57 patients suffered grade 3-4 treatment-emergent adverse events, with the most commonly reported being hypokalemia and abdominal pain (each three [5%] patients).
• Ten (18%) patients suffered serious treatment-emergent adverse events and two (4%) of these adverse events (ie, chills and infusion-related reaction) were attributed to treatment; no treatment-related deaths were reported.