Vinorelbine With or Without Thiotepa for HER2-Negative Metastatic Breast Cancer: A Propensity Score Analysis.

Background: Vinorelbine is commonly used to treat metastatic breast cancer (mBC), while thiotepa is known for its ability to cross the blood-brain barrier.

Methods: Our retrospective study aimed to compare the efficacy and safety of vinorelbine with or without thiotepa in patients with HER2-negative mBC. We used propensity score inverse probability of treatment weighting to ensure comparability between groups.

Results: Vinorelbine-thiotepa was not significantly associated with improved median progression-free survival (PFS) (4.9 vs. 3.0 months, p = 0.138) or median overall survival (OS) (11.8 vs. 11.9 months, p = 0.961) compared to vinorelbine. However, in the central nervous system (CNS) metastasis subgroup, vinorelbine-thiotepa was associated with a longer median PFS (4.9 vs. 2.1 months, p = 0.013) and CNS-PFS (6.12 vs. 2.20 months, p = 0.007). The combination was also associated with a higher rate of grade ≥ 3 adverse events (54.3% vs. 37.9%, p = 0.021).

Conclusion: While no overall benefit in PFS or OS was found, vinorelbine-thiotepa may be associated with improved PFS in mBC patients with CNS metastasis.