Phase II Trial of Trilaciclib, Pembrolizumab, Gemcitabine and Carboplatin in Metastatic Triple-Negative Breast Cancer

This is an open label, single-arm, phase II trial designed to evaluate the efficacy of trilaciclib, pembrolizumab, gemcitabine and carboplatin in participants with locally advanced unresectable or metastatic triple-negative breast cancer. Pembrolizumab will be given for a maximum of 2 years. Eligible participants will receive the study treatment until disease progression, unacceptable toxicity, or withdrawal for any reason. A tumor biopsy will be collected from participants in which it can be safely obtained before the first dose of treatment, prior to Cycle 3 Day 1, and at the time of disease progression (optional). Blood specimens for correlative studies will be collected pre-treatment Cycle 1 Day 1, prior to treatment Cycle 2 Day 1, prior to treatment Cycle 3 Day 1, 3 months after the start of study treatment, and 6 months after the start of study treatment.