The Clinical Outcomes and Safety of Sacituzumab Govitecan in Heavily Pretreated Metastatic Triple-Negative and HR+/HER2- Breast Cancer: A Multicenter Observational Study from Turkey.

Background/Objectives: Sacituzumab govitecan (SG) is an antibody-drug conjugate targeting Trop-2, approved for use in metastatic triple-negative breast cancer (mTNBC) and more recently in the hormone receptor-positive/HER2-negative (mHRPBC) subtype. While clinical trials have demonstrated its efficacy, real-world data-especially those involving both molecular subtypes-remain scarce. This multicenter, retrospective study aimed to evaluate real-world observational data describing the clinical outcomes, safety, and prognostic factors associated with SG treatment in patients with mTNBC or mHRPBC. Methods: A total of 68 patients treated with SG between 2022 and 2025 were included from multiple oncology centers in Turkey. Patients with mTNBC were required to have received at least one prior chemotherapy line, while mHRPBC patients had received at least two prior chemotherapy lines in addition to cyclin-dependent kinase 4 and 6 inhibitors (CDK 4/6) plus hormone therapy. The clinical outcomes-including the progression-free survival (PFS), overall survival (OS), and objective response rate (ORR)-were evaluated. Univariate and multivariate analyses were performed to identify factors influencing outcomes. Adverse events (AEs) were also documented and graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 5 (NCI-CTCAE v5.0). Results: The cohort included 35 (51.5%) mTNBC and 33 (48.5%) mHRPBC patients. The median PFS was 6.1 months, and the median OS was 12.5 months, with no significant differences between subtypes. The ORR was 52.9%, with a complete response observed in 10.3% of patients. A high Eastern Cooperative Oncology Group Performance Status (ECOG PS) and liver metastasis were independent predictors of poorer PFS and OS. Prior immunotherapy did not negatively impact SG's efficacy. SG was generally well tolerated; the most common AEs were alopecia, anemia, neutropenia, and diarrhea. Treatment discontinuation due to AEs was rare (2.9%). Conclusions: SG was associated with similar clinical outcomes and tolerability in both the mTNBC and mHRPBC subtypes. Although the real-world PFS and OS outcomes mirror those seen in clinical trials, the absence of a control group means that these findings should be interpreted descriptively rather than as confirmation of treatment efficacy. Importantly, this study provides one of the first real-world datasets evaluating SG in the mHRPBC subgroup, highlighting its potential role beyond clinical trials. These results support SG as a valuable therapeutic option in heavily pretreated patients, warranting further prospective and biomarker-driven studies.