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

Background Combination of pertuzumab, trastuzumab and chemotherapy is standard of care for first-line treatment of patients with human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer. Most randomized studies used combination of taxanes and anti HER2 targeted treatment as 1st line treatment. The combination of vinorelbine, trastuzumab and pertuzumab has shown anti-tumor activity in a phase 2 trial. No trials have compared outcomes between vinorelbine to taxane in combination with pertuzumab and trastuzumab. Methods We retrospectively evaluated all patients with metastatic HER-2 positive breast cancer treated in two institutions between 3/2013 and 3/2018. Patients9 clinical data were obtained from electronic medical records. We identified patients who were treated with vinorelbine (oral or intravenous) or a-taxane (docetaxel or paclitaxel) in combination with trastuzumab and pertuzumab as a first-line treatment. We compared progression free survival (PFS), overall survival (OS) and toxicity profiles between the two groups. Results The study included 120 patients (73 in the taxane and 47 in the vinorelbine group). There were several between-group differences: 65% of the taxane group patients were metastatic at diagnosis compared to 40% in the vinorelbine group (p=0.008), 18% of the taxane group received trastuzumab in the adjuvant setting vs. 45% in the vinorelbine group (p=0.003). More patients in the taxane group were asymptomatic (43.4% vs 23.4%, p=0.04). PFS was significantly longer in the taxane group compared to the vinorelbine group (35.4 months vs 13.9 months, p=0.0005). OS was also longer in the taxane group, but difference did not reach statistical significance (48.8 months vs 34.5 months, p=0.13). In the subgroup of patients with recurrent disease (excluding patients with de-novo metastatic disease), there was no difference for OS (32.6 vs 33.1 months for taxane and vinorelbine, respectively). Toxicity profiles differed between the groups, with more patients in the taxane group experiencing diarrhea, peripheral neuropathy and asthenia, and more patients in the vinorelbine group experiencing neutropenia. Discontinuation of chemotherapy due to toxicity was more common in the taxane group compared to the vinorelbime group. (38% vs. 17%, p=0.015). Conclusions In this retrospective analysis, first-line treatment with taxane combined with trastuzumab and pertuzumab for HER-2 positive metastatic breast cancer resulted in improved outcomes compared with the combination of vinorelbine, trastuzumab and pertuzumab. The vinorelbine arm revealed a favorable toxicity profile. Patients with recurrent disease (excluding de-novo metastatic disease) had similar outcomes with either chemotherapy. A randomized study is warranted. Citation Format: Daniel Jack Reinhorn, Irina Kuchuk, Judit Prus, Michal Sarfaty, Hadar Goldvaser, Ofer Rotem, Daniel Hendler, Dalia Zoref, Victoria Neiman, Tzipora Shohat, Olga Ulitsky, Shlomit Yust-Katz, Bella Nisenbaum, Maya Gottfried, Rinat Yerushalmi. Taxane versus vinorelbine in combination with pertuzumab and trastuzumab for first-line treatment of patients with metastatic HER2-positive breast cancer - A retrospective two-center study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-18-33.