Pembrolizumab for metastatisc breast cancer with high tumor mutational burden

The TAPUR (Targeted Agent and Profiling Utilization Registry) Study is a phase 2 basket study that aims to identify signals of antitumor activity of commercially available targeted agents in patients with advanced cancer harboring genomic alterations known to be drug targets. One of the TAPUR cohorts consists of patients with heavily pretreated metastatic breast cancer with high tumor mutational burden (9 to 37 mutations per megabase) treated with pembrolizumab monotherapy. Disease control for at least 16 weeks was seen in 37% of patients (95% CI 21-50) and objective response in 21% (8-41); median PFS was 10.6 weeks (7.7-21.1) and median OS was 30.6 weeks (18.3-103.3). The authors conclude that pembrolizumab monotherapy has antitumor activity in heavily pretreated patients with MBC characterized by high TMB.