Assessment of weight change and BMI as prognostic markers of survival outcomes in sacituzumab govitecan therapy for mTNBC in a Polish female cohort.

Abstract

e13144 Background: Body mass index (BMI) and weight changes are often studied as prognostic markers in breast cancer (BC). While higher BMI is associated with worse outcomes in hormone receptor-positive early breast cancer, the "obesity paradox" suggests improved survival in advanced BC, including metastatic triple-negative breast cancer (mTNBC). Sacituzumab govitecan (SG), an antibody-drug conjugate, has shown better efficacy than chemotherapy in relapsed/refractory mTNBC across BMI subgroups. However, the role of BMI and weight changes in influencing SG efficacy and safety in real-world population remains unclear. This study evaluates the impact of BMI and weight changes on progression-free survival (PFS), overall survival (OS), and adverse events (AEs) in a Polish cohort treated with SG. Methods: This retrospective study included 83 women with unresectable locally advanced or metastatic TNBC treated with SG between August 2021 and September 2024 in four Polish oncology centers. Data on BMI, weight changes, PFS, OS, and AEs were collected. Patients were classified into BMI categories based on World Health Organization guidelines: underweight ( < 18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²), and obese (≥30.0 kg/m²). Weight change was defined as the difference between baseline weight at treatment initiation and weight at the final SG cycle. Statistical analyses included multivariate Cox regression for PFS/OS, and chi-square or Fisher’s exact tests for associations between BMI/weight changes and AEs. Results: At baseline, 3.6% were underweight, 49.4% normal weight, 22.9% overweight, and 24,1% obese. Median PFS was 4.07 months, and median OS was 8.01 months. No significant correlations were found between baseline weight, BMI, or weight changes and PFS/OS. For PFS: baseline weight: HR = 0.990 (95% CI: 0.956–1.026, p = 0.595), BMI categories: normal weight HR = 0.768 (95% CI: 0.388–1.518, p = 0.447), obesity HR = 0.916 (95% CI: 0.362–2.317, p = 0.854), weight change: HR = 1.017 (95% CI: 0.953–1.085, p = 0.618). For OS: baseline weight: HR = 0.975 (95% CI: 0.933–1.018, p = 0.252), BMI categories: normal weight HR = 0.670 (95% CI: 0.307–1.460, p = 0.313), obesity HR = 0.782 (95% CI: 0.263–2.325, p = 0.658), weight change: HR = 0.963 (95% CI: 0.904–1.027, p = 0.249). Weight stability/gain or weight loss showed no correlation with AE incidence or severity (p > 0.05). The most common grade ≥2 AE was neutropenia (63.9%), with no BMI or weight change association. Conclusions: In this real-world cohort, BMI and weight changes did not serve as prognostic factors for survival outcomes or correlate with adverse events in patients with mTNBC treated with SG. These findings highlight the need for alternative biomarkers to stratify risk and optimize treatment.