Statement: Cohort 1 of the primary trial produced better Objective Response Rate results than cohort 2.
Primary_evidence: Outcome Measurement:    Objective Response Rate (ORR)   ORR was defined as percentage of participants with confirmed best overall response (BOR) of complete response (CR) or partial response (PR) using independent imaging review (IIR) based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. BOR of CR and PR was confirmed by a subsequent CR assessment and CR or PR assessment, respectively at least 4 weeks later. CR: disappearance of all measurable, non-measurable lesions and no unequivocal new lesions. Any pathological lymph nodes (target or non-target) had to be reduced in short axis to less than (<) 10 millimeter (mm). PR: at least a 30 percent (%) decrease in sum of diameters (SOD) of target lesions, taking as reference the baseline SOD and there are no unequivocal new lesions, and no progression of non-target disease. The 2-sided 95% confidence interval (CI) calculated by Clopper-Pearson method. As planned, data up to the primary completion date only were analyzed.   Time frame: From date of first dose of study drug administration to date of first documentation of disease progression or death, whichever occurred first (up to 3 years 11 months) Results 1:    Arm/Group Title: Stratum 1: Eribulin Mesylate + Pembrolizumab   Arm/Group Description: Participants with mTNBC who were never treated with systemic anticancer therapy in the metastatic setting received eribulin mesylate 1.4 mg/m^2, intravenous infusion on Days 1 and 8 and pembrolizumab 200 mg, intravenous infusion on Day 1 in Treatment Cycle 1 (safety run-in, Phase 1b) and then continued in each 21-days Treatment Cycles in the presence of clinical benefit until confirmed disease progression, development of unacceptable toxicity, participant request, withdrawal of consent, or study termination by the sponsor in Phase 2 in the Stratum 1.   Overall Number of Participants Analyzed: 66   Measure Type: Number   Unit of Measure: percentage of participant  25.8        (15.8 to 38.0) Results 2:    Arm/Group Title: Stratum 2: Eribulin Mesylate + Pembrolizumab   Arm/Group Description: Participants with mTNBC previously treated with 1 to 2 lines of systemic anticancer therapy in the metastatic setting received eribulin mesylate 1.4 mg/m^2, intravenous infusion on Days 1 and 8 and pembrolizumab 200 mg, intravenous infusion on Day 1 in Treatment Cycle 1 (safety run-in, Phase 1b) and then continued in each 21-days Treatment Cycles in the presence of clinical benefit until confirmed disease progression, development of unacceptable toxicity, participant request, withdrawal of consent, or study termination by the sponsor in Phase 2 in the Stratum 2.   Overall Number of Participants Analyzed: 101   Measure Type: Number   Unit of Measure: percentage of participant  21.8        (14.2 to 31.1)