Taxane versus vinorelbine in combination with trastuzumab and pertuzumab for first-line treatment of metastatic HER2-positive breast cancer: a retrospective two-center study

Background: The combination of a taxane with trastuzumab and pertuzumab is standard of care for first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The combination of vinorelbine with trastuzumab and pertuzumab showed anti-tumor activity in a phase 2 trial. Patients and methods: The databases of two tertiary medical centers were retrospectively searched for patients with HER2-positive metastatic breast cancer who underwent first-line treatment in 2013–2019 with a taxane or vinorelbine in combination with trastuzumab and pertuzumab. Groups were compared for progression-free survival (PFS), overall survival (OS), and toxicity profile. Results: The study included 87 patients in the taxane group and 65 in the vinorelbine group. Overall median PFS was significantly longer in the taxane group [HR 0.56 (0.36–0.88), P = 0.01], but on multivariate analysis the difference was not statistically significant [HR 0.68 (0.4–1.1, P = 0.11)]. PFS was comparable in both groups of patients with recurrent disease [HR 0.94 (0.5–1.79), P = 0.85]. However, in patients with de novo metastatic disease, the difference in favor of the taxane group was pronounced [HR 0.4 (0.2–0.78), P = 0.007] and maintained significance on multivariate analysis [HR 0.46 (0.2–0.97, P = 0.04)]. There was no statistical significant difference in OS in the whole cohort [HR 0.69 (0.39–1.23)] or the subgroups. Conclusions: Patients with HER2-positive metastatic breast cancer had similar survival with first-line treatment of taxane or vinorelbine combined with trastuzumab and pertuzumab. When the analysis was adjusted for prognostic factors, there was no PFS benefit for taxanes except in the subgroup with de novo disease.