In a Chinese phase II trial reported in the Journal of Clinical Oncology by Ma et al, the combination of the pan-ErbB inhibitor pyrotinib and capecitabine improved response rate vs lapatinib/capecitabine in women with HER2-positive relapsed or metastatic breast cancer previously treated with taxanes, anthracyclines, and/or trastuzumab.
In the open-label multicenter study, 128 patients were randomly assigned between May 2015 and March 2016 to receive oral pyrotinib 400 mg/day (n = 65) or oral lapatinib 1,250 mg/day (n = 63) in 21-day cycles, plus oral capecitabine 1,000 mg/m2 twice per day on days 1 to 14.
Prior trastuzumab had been received in the neoadjuvant, adjuvant, or metastatic setting by 54% of patients in both groups.
The primary endpoint was investigator-assessed overall response rate on RECIST v1.1.
Median follow-up was 14.9 months. Objective response was observed in 51 patients (78.5%) in the pyrotinib group vs 36 patients (57.1%) in the lapatinib group (P = .01). Median duration of response was 16.7 months vs 8.4 months. Median progression-free survival was 18.1 months vs 7.0 months (adjusted hazard ratio [HR] = 0.36, P < .001). Unadjusted HRs were 0.37 (P = .0031) among patients with prior trastuzumab and 0.37 (P = .0013) among those without prior trastuzumab. Overall survival data were not mature; at the time of analysis, 24 patients in the pyrotinib group and 28 patients in the lapatinib group had died.
Grade 3 or 4 adverse events occurred in 61.3% of the pyrotinib group and 47.6% of the lapatinib group, with the most common in the pyrotinib group being hand-foot syndrome (24.6% vs 20.6%), diarrhea (15.4% vs 4.8%), decreased neutrophil count (9.2% vs 3.2%), and decreased white blood cell count (7.7% vs 1.6%). No febrile neutropenia was observed, and no grade ≥ 3 cardiac events were reported.
The investigators concluded, “In women with HER2-positive metastatic breast cancer previously treated with taxanes, anthracyclines, and/or trastuzumab, pyrotinib plus capecitabine yielded statistically significant better overall response rate and progression-free survival than lapatinib plus capecitabine in this randomized phase II trial.”
Binghe Xu, MD, of the Department of Medical Oncology, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by Jiangsu Hengrui Medicine, CAMS Initiative for Innovative Medicine, and National Science and Technology Major Project of the Ministry of Science and Technology. For full disclosures of the study authors, visit jco.ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.