Pyrotinib, an irreversible pan-ErbB inhibitor, provides an effective treatment option in combination with capecitabine for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer, according to results of a phase 3 trial to be presented later this month in the 2020 American Society of Clinical Oncology (ASCO) Virtual Scientific Program.
The open-label, multicenter PHOEBE trial enrolled patients with HER2-positive metastatic breast cancer following treatment with trastuzumab and taxanes and/or anthracyclines; patients had 0 to 2 previous lines of chemotherapy for metastatic disease. Patients were randomized in a 1:1 ratio to receive pyrotinib 400 mg or lapatinib 1,250 mg daily on a continuous basis in combination with capecitabine 1,000 mg/m2 on days 1 to 14 of 21-day cycles. Of 267 enrolled patients, 266 received study treatment and were included in the analysis. The trial's primary end point was progression-free survival.
At the planned interim analysis, pyrotinib/capecitabine resulted in a median progression-free survival of 12.5 months, compared with 6.8 months for lapatinib/capecitabine. Pyrotinib/capecitabine also resulted in prolonged progression-free survival among patients resistant to trastuzumab (12.5 months vs 6.9 months), but the difference did not reach statistical significance. The most frequent adverse events of grade 3 or higher were diarrhea (30.6% for pyrotinib/capecitabine vs 8.3% for lapatinib/capecitabine) and hand-foot syndrome (16.4% vs 15.2%).
"In patients with HER2+ metastatic breast cancer after trastuzumab and chemotherapy, pyrotinib plus capecitabine achieved a significant better progression-free survival than lapatinib plus capecitabine, with manageable toxicity, verifying the phase 2 findings," conclude the investigators, led by first author Binghe Xu, MD, PhD, Professor and Director of the Department of Medical Oncology at the Cancer Hospital and Institute of the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing, China.
For More Information
Xu B, Yan M, Ma F, et al (2020). Pyrotinib or lapatinib plus capecitabine for HER2+ metastatic breast cancer (PHOEBE): a randomized phase III trial. J Clin Oncol (ASCO Virtual Scientific Program), 38(suppl_15). Abstract 1003. DOI:10.1200/JCO.2020.38.15_suppl.1003
Image credit: Steve Seung-Young Lee. Courtesy of the National Cancer Institute / University of Chicago Comprehensive Cancer Center