OBJECTIVES: To assess the relative benefit of sacituzumab govitecan (SG) versus single-agent chemotherapy of physician’s choice (eribulin, vinorelbine, capecitabine, or gemcitabine) in patients with relapsed or refractory metastatic triple-negative breast cancer, using the number needed to treat (NNT) methodology.

METHODS: Data from the ASCENT study (NCT02574455) was considered. The number needed to treat (NNT) was calculated not only by absolute risk reduction (NNT_ARR), but also using the restricted mean survival time (NNT_RMST) given its ability to reflect the treatment effect during a follow-up period rather than at a specific time point. The analysis considered the progression-free survival (PFS) and overall survival (OS) at 12 months across the intention to treat (ITT) population (including patients with stable brain metastases) and also patients without brain metastasis (WBM).

RESULTS: Comparing SG versus single-agent chemotherapy (CT), the NNTRMST results for PFS endpoint in the ITT and WBM populations were as follows: 1.21 (95% IC 0.87 to 1.91) and 0.89 (95% IC 0.68 to 1.21), respectively. For OS, the NNTRMST results obtained in ITT and WBM were 3.17 (95% IC 2.34 to 4.72) and 2.94 (95% IC 2.18 to 4.31), respectively. Summarized NNTARR results for PFS were 9.72 and 7.25, while for OS were 3.85 and 3.56, respectively in ITT and WBM populations.

CONCLUSIONS: The results indicate a low NNT for sacituzumab govitecan when compared to single agent chemotherapy for both PFS and OS endpoints. NNT_RMST were lower than NNT_ARR emphasizing the relevance of considering the effect of SG during follow-up, especially in a context such as refractory metastatic triple-negative breast cancer. Additionally, it was also observed that the results for ITT and WBM populations were very similar, thus representing the benefit of SG for both populations. These findings may inform decisions regarding treatment and resource allocation for refractory metastatic triple-negative breast cancer.