To The Editor,

I want to congratulate De Moura and their colleagues [1] in which the authors assessed the real-world effectiveness and safety of sacituzumab govitecan (SG) in patients with metastatic triple-negative breast cancer (mTNBC) treated at Institut Curie Hospitals, with a focus on patients with brain metastases. They concluded that the observed response rate and safety of SG are consistent with the results of the ASCENT trial [2], with efficacy observed in patients with brain metastases, but observed PFS and OS are numerically shorter. In the ASCENT trial, median PFS was 5.6 months versus 3.9 months in their cohort whereas median OS was.

12.1 months versus 8.6 months in their cohort. In their paper, the authors offered multiple explanations for the numerical shorter lengths of PFS and OS.

I would like to add one more. In their study, patients had previously received a median of two lines of treatment (range: 1–10); however, in the ASCENT trail, they had received a median of three lines of treatment (range: 3–16). In the ASCENT trial, the majority of patients (71%) had previously undergone two or three lines of chemotherapy. Nevertheless, the current study did not describe this particular detail. Less SG efficacy in the current study compared to the ASCENT trial would be expected if the majority of patients received SG following three lines of prior chemotherapy regimen. More research should be done on this matter.