Background: Resistance to standard taxane-based chemotherapy is common in TNBC. Preclinical data suggest that MEK inhibition may overcome taxane resistance and enhance antitumor immune response. The safety and efficacy of combining C, a highly selective MEK inhibitor, with P was explored in pts with metastatic/locally advanced TNBC and no prior systemic therapy for metastatic disease. Methods: The COLET study (NCT02322814; EudraCT number, 2014-002230-32) consisted of a safety run-in (n ?