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

## TL;DR

This study compared vinorelbine with or without thiotepa in HER2-negative metastatic breast cancer patients, finding potential benefits in brain metastasis cases.

## Contribution

The novel contribution is identifying improved progression-free survival in CNS metastasis patients using vinorelbine–thiotepa.

## Key findings

- Vinorelbine-thiotepa did not improve overall survival or progression-free survival in general HER2-negative metastatic breast cancer patients.
- In patients with central nervous system metastases, vinorelbine-thiotepa was associated with significantly longer progression-free survival.
- The combination therapy had a higher rate of severe adverse events compared to vinorelbine alone.

## Abstract

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

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.

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).

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

Comparative analysis of thiotepa plus vinorelbine versus vinorelbine alone in patients with HER2‐negative metastatic breast cancer, using a propensity score emulated target trial. While no progression‐free survival benefit was observed in the overall population, vinorelbine–thiotepa was associated with significantly improved median progression‐free survival in patients with central nervous system metastases.