Pyrotinib plus capecitabine improved progression-free survival (PFS) when compared with lapatinib plus capecitabine in patients with HER2-positive metastatic breast cancer, according to phase 3 trial results published in The Lancet Oncology.
The PHOEBE trial (ClinicalTrials.gov Identifier: NCT03080805) enrolled 267 patients from 29 hospitals in China. The patients had pathologically confirmed HER2-positive metastatic breast cancer and had previously received trastuzumab and taxanes.
The patients were randomly assigned to receive pyrotinib plus capecitabine (n=134) or lapatinib plus capecitabine (n=132).
At the interim analysis data cutoff (March 31, 2019), the median follow-up was 10.5 months for the pyrotinib arm and 9.7 months for the lapatinib arm.
The median PFS was 12.5 months in the pyrotinib arm and 6.8 months in the lapatinib arm (hazard ratio [HR], 0.39; 95% CI, 0.27-0.56; 1-sided P <.0001), which met the criterion for statistical significance.
At the cutoff for the overall survival (OS) analysis (March 31, 2020), the median follow-up was 21.8 months for the pyrotinib arm and 21.5 months for the lapatinib arm.
The median OS was 26.8 months for the pyrotinib arm and was not reached for the lapatinib arm. The estimated 12-month OS rate was 90.9% and 80.1%, respectively.
Grade 3 or higher adverse events (AEs) occurred in 64% of patients in the pyrotinib arm and 43% of those in the lapatinib arm. The most common grade 3 or higher AEs were diarrhea (31% in the pyrotinib arm and 8% in the lapatinib arm) and hand-foot syndrome (16% and 15%, respectively).
Serious AEs were observed in 10% of patients in the pyrotinib arm and 8% of those in the lapatinib arm.
There were no treatment-related deaths in the pyrotinib arm, but there was 1 sudden death in the lapatinib arm that was considered related to treatment.
“The findings from this study suggest that pyrotinib plus capecitabine is a novel treatment for patients with HER2-positive metastatic breast cancer after trastuzumab and chemotherapy and is an alternative option to the current treatment landscape, particularly in regions with scarce access to HER2-directed drugs,” the study authors wrote.
Disclosures: This research was supported by Jiangsu Hengrui Medicine and the National Key R&D Program of China. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Xu B, Yan M, Ma F, et al. Pyrotinib plus capecitabine versus lapatinib plus capecitabine for the treatment of HER2-positive metastatic breast cancer (PHOEBE): a multicentre, open-label, randomised, controlled, phase 3 trial. Lancet Oncol. 2021;22(3):351-360. doi:10.1016/S1470-2045(20)30702-6