ESMO World GI: Pembrolizumab Plus Ibrutinib Under Study in Metastatic Colorectal Cancer
Posted: Monday, July 27, 2020
Combination drug therapy of the Bruton’s tyrosine kinase inhibitor ibrutinib and the PD-1 checkpoint inhibitor pembrolizumab was under study in patients with refractory microsatellite-stable colorectal cancer, according to the findings of a phase I/II study, presented during the European Society for Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer 2020 Virtual (ESMO World GI; Abstract P-47). Treated patients did not appear to experience any dose-limiting toxicities from the combination, according to Richard Kim, MD, of Moffitt Cancer Center, Tampa, Florida, and colleagues. However, based on their findings, the investigators do not believe the combination warrants further study in this patient population.
A total of 38 patients with microsatellite-stable colorectal cancer who had received previous front-line treatment were enrolled in the study. The study utilized a standard 3+3 dose-escalating strategy. Cohort 0 received 420 mg of ibrutinib orally daily, and cohort 1 received 560 mg of ibrutinib orally daily. Both cohorts were intravenously administered 200 mg of pembrolizumab every 3 weeks. During phase I, 8 patients received at least one treatment dose, and during phase II, 30 patients received at least a single treatment dose.
In the phase I part of the study, the investigators reported the maximum tolerated dose to be 560 mg of ibrutinib daily with intravenous administration of 200 mg of pembrolizumab every 3 weeks. No dose-limiting toxicities were reported. In the phase II part of the study, there was a disease control rate of 3.6% at 4 months. In addition, the median overall survival was 5.32 months, and the median progression-free survival was 1.54 months. Furthermore, patients experienced grade 3 or 4 adverse events including anemia (21.1%), increased alkaline phosphatase (7.9%), and fatigue (7.9%).
Disclosure: The study authors reported no conflicts of interest.