Docetaxel rechallenge in HER2-negative metastatic breast cancer: a real-world study of previously discontinued patients for non-progression reasons.

Purpose: This study aimed to evaluate the efficacy and safety of docetaxel rechallenge in HER2-negative metastatic breast cancer (MBC) patients who discontinued docetaxel for reasons other than disease progression.

Patients and methods: We retrospectively analyzed HER2-negative MBC patients treated with docetaxel-based therapy (DBT) at our institution from 2010 to 2020. Objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were assessed. Multivariate Cox regression and propensity score matching analysis (PSMA) were used to minimize bias.

Results: Among 600 patients, 369 only received docetaxel once (control group), while 231 (38.5%) received docetaxel rechallenge as second or later-line therapy (rechallenge group). In the second-line rechallenge subset (143 patients), ORR was 51.0%, and PFS was 6.7 months. Multivariate analysis showed that a response to initial DBT (stable disease [SD] vs. complete response/partial response [CR/PR]: odds ratio [OR] 2.615, 95% confidence interval [CI] 1.373-4.981; p = 0.03) independently predicted the ORR. Beyond second-line rechallenge, the ORR and PFS were 37.5% and 5.6 months, respectively. After PSMA, the rechallenge group demonstrated significantly improved OS compared to the control group: 50.5 months vs. 46.0 months (Hazard Ratio [HR] 0.632; 95% CI 0.455-0.878; p = 0.006). The toxicities reported were manageable, primarily hematologic, with grade 3-4 events occurring in 19.5% of cases.

Conclusion: This study suggests that docetaxel rechallenge may be an effective and tolerable later-line treatment option for patients with HER2-negative MBC, particularly those who responded to initial DBT. However, further prospective, randomized controlled research is needed to fully evaluate its impact on disease response in this patient population.