Sacituzumab-induced severe or febrile neutropenia and G-CSF utilization and cost for advanced HER2-negative breast cancer: a single-center retrospective analysis

PURPOSE: Severe neutropenia (SN) and febrile neutropenia (FN) are clinically significant safety concerns of sacituzumab govitecan-hziy (SG). We sought to compare the rates of SN and FN from clinical trials to real-world experience, correlate factors with SN and FN, and quantify granulocyte colony-stimulating factor (G-CSF) use in HER2-negative (HER2-) metastatic breast cancer (mBC). METHODS: We performed a retrospective analysis of patients treated with SG for advanced HER2- BC at a single US institution with a diverse patient population. The rates of SN and FN, stratified by receptor status, were compared to their respective phase III clinical trials. Multivariable logistic regression was used to evaluate factors associated with SN and FN. RESULTS: Of 87 patients treated with SG, 10 patients received primary prophylaxis. Of the 77 patients who didn't receive primary G-CSF prophylaxis, 49% and 3.9% patients developed SN and FN, respectively. SN and FN rates did not differ in the HR + /HER- mBC or mTNBC subgroups compared to clinical trials. Factors evaluated in this study were not shown to be associated with SN. Overall, 44% (38/87) required a dose interruption or reduction due to SN or FN. 11% (10/87) and 60% (52/87) received G-CSF as primary and secondary prophylaxis respectively, with a total G-CSF drug cost of $2.1 million. CONCLUSIONS: SG-induced SN and FN rates were similar to those reported in clinical trials, both in the HR + /HER- mBC and mTNBC groups. Due to small sample size, we did not identify any statistically significant risk factors of SG-associated SN. Our study provided insights into G-CSF use patterns and costs in real-world SG therapy.