Effectiveness of sacituzumab govitecan and management of neutropenia in patients with metastatic triple-negative breast cancer treated in real-world settings in the United States

Background: Sacituzumab govitecan (SG), a Trop-2-directed antibody-drug conjugate, demonstrated efficacy and manageable safety in second-line or later (2L+) metastatic triple-negative breast cancer (mTNBC) in clinical trials. We describe the real-world effectiveness of SG as 2L+ mTNBC treatment and the proportion of patients with neutropenia and its management. Patients and methods: This study used a nationwide electronic health record-derived de-identified database. Patients with mTNBC receiving SG in 2L+ from April 2020 through June 2023 were included. Real-world overall survival (rwOS) and time to next treatment or death (TTNTD) were assessed using the Kaplan–Meier method. SG use patterns, rates of neutropenia, and granulocyte colony-stimulating factor (G-CSF) use were described. Results: For 381 patients included in the analysis, the median [interquartile range (IQR)] age was 61 years (52-69 years); 17% (n = 66) had ECOG PS ≥2; 18% (n = 70) were black; 78% (n = 298) were treated in community settings. Patients received a median (IQR) of 2 (1-3) prior treatment lines for metastatic disease. Median (IQR) SG treatment duration was 4.0 months (1.9-7.6 months) (maximum 32.7 months). At a median (IQR) follow-up of 8.7 months (4.5-14.6 months), the median rwOS and TTNTD were 11.3 months [95% confidence (CI) 10.0-12.9 months] and 5.6 months (95% CI 5.0-6.4 months), respectively. Grade 2 and 3/4 neutropenia during SG treatment occurred in 25% (n = 94) and 27% (n = 101) of patients, respectively. Any G-CSF use (primary + secondary prophylaxis and/or treatment) was observed in 59% (n = 225) of patients; 31% (n = 117) received any G-CSF prophylaxis. Any-grade neutropenia occurred in 25% (n = 29) of patients receiving any G-CSF prophylaxis versus 44% (n = 68) of patients who did not receive G-CSF. Conclusions: SG demonstrated real-world effectiveness and manageable safety, consistent with findings from ASCENT and other published real-world studies. Patients receiving any G-CSF prophylaxis had low rates of any-grade neutropenia, suggesting SG-related neutropenia can be effectively managed with G-CSF in patients with increased risk for febrile neutropenia.