Sacituzumab Govitecan in Untreated, Advanced Triple-Negative Breast Cancer

BACKGROUND: Patients with previously untreated, locally advanced, unresectable or metastatic triple-negative breast cancer who are not candidates for inhibitors of programmed cell death protein 1 (PD-1) or programmed death ligand 1 (PD-L1) have limited treatment options. METHODS: In this international, phase 3, open-label, randomized trial, we enrolled patients with previously untreated, advanced triple-negative breast cancer who were not candidates for PD-1 or PD-L1 inhibitors owing to previous use or coexisting conditions. Patients had either PD-L1-negative tumors with a combined positive score (CPS; the number of PD-L1-staining tumor cells, lymphocytes, and macrophages divided by the total number of viable tumor cells, multiplied by 100) of less than 10 or PD-L1-positive tumors with a CPS of 10 or higher and were assigned in a 1:1 ratio to receive sacituzumab govitecan or chemotherapy (paclitaxel, nanoparticle albumin-bound paclitaxel, or gemcitabine plus carboplatin). The primary end point was progression-free survival, assessed by blinded independent central review. Secondary end points included overall survival, objective response, the duration of response, and safety. RESULTS: Among 558 patients, median progression-free survival was 9.7 months (95% confidence interval [CI], 8.1 to 11.1) with sacituzumab govitecan and 6.9 months (95% CI, 5.6 to 8.2) with chemotherapy (stratified hazard ratio for disease progression or death, 0.62; 95% CI, 0.50 to 0.77; P<0.001). An objective response was confirmed in 48% of patients (95% CI, 42 to 54) who received sacituzumab govitecan and 46% (95% CI, 40 to 52) who received chemotherapy; the median response duration was 12.2 months (95% CI, 9.7 to 13.8) and 7.2 months (95% CI, 5.7 to 8.4), respectively. Adverse events of grade 3 or higher occurred in 66% of patients who received sacituzumab govitecan (most frequently neutropenia [in 43%], diarrhea [in 9%], and leukopenia [in 7%]) and in 62% of patients who received chemotherapy (most frequently neutropenia [in 41%], anemia [in 16%], and leukopenia [in 13%]). The incidence of adverse events that led to discontinuation of sacituzumab govitecan or at least one chemotherapy drug was 4% and 12%, respectively. CONCLUSIONS: Sacituzumab govitecan led to significantly longer progression-free survival than chemotherapy among patients with advanced triple-negative breast cancer who were not candidates for treatment with PD-1 or PD-L1 inhibitors. The incidence of adverse events of grade 3 or higher with sacituzumab govitecan was similar to that with chemotherapy, but adverse events were common. (Funded by Gilead Sciences; ASCENT-03 ClinicalTrials.gov number, NCT05382299.).