Safety and Efficacy Study of Vintafolide and Vintafolide Plus Paclitaxel Compared to Paclitaxel Alone in Participants With Triple Negative Breast Cancer (TNBC) (MK-8109-004)

During the screening stage, participants will be required to have a diagnostic computed tomography (CT) scan with etarfolatide (EC20) to identify target lesions and determine eligibility for treatment. After successful screening, during the treatment stage, participants will receive study drug (vintafolide, vintafolide + paclitaxel, or paclitaxel) for approximately four 28-day cycles.