ESMO 2021: Interim Phase II Results With Dalpiciclib Plus Pyrotinib in HER2-Positive Breast Cancer
Posted: Friday, October 8, 2021
Min Yan, MD, of Henan Cancer Hospital/Affiliated Cancer Hospital of Zhengzhou University, China, and colleagues evaluated the safety and efficacy of dalpiciclib, a novel CDK4/6 inhibitor, plus the HER2-targeting tyrosine kinase inhibitor pyrotinib in patients with advanced breast cancer. Presented during the European Society for Medical Oncology (ESMO) Congress 2021 (Abstract 276P), their results concluded that this drug combination demonstrated manageable toxicity and promising efficacy. Notably, the authors suggested it may be “considered as a completely oral, chemotherapy-free regimen for patients with HER2-positive advanced breast cancer.”
The first stage of this single-arm, phase II study enrolled a total of 24 patients with HER2-positive advanced breast cancer who received at most one line of prior systemic therapy; prior HER2-targeted tyrosine kinase and CDK4/6 inhibitors were not allowed. Participants were administered 125 mg of dalpiciclib daily for 3 weeks with 1 off week and 400 mg of pyrotinib daily in 28-day cycles.
A total of 13 patients had hormone receptor (HR)-positive disease, 16 were previously treated with trastuzumab, and 22 had visceral metastasis. A confirmed objective response rate was observed in 15 of 23 evaluable patients, made up of 100% of HR-negative and 38.5% of HR-positive individuals achieving a partial response; stable disease and progressive disease were reported in 6 and 2 patients, respectively. Patients who had zero (69.2%) versus one (60.0%) line of previous therapy, as well as those who were trastuzumab-sensitive (66.7%) versus -resistant (63.6%), had similar response rates.
Grade 3 or 4 adverse events occurred in 15 patients, although most were reported to be tolerable, and 1 patient needed a dose reduction. The most common adverse events included neutropenia, leukopenia, and diarrhea, which affected 54.2%, 50.0%, and 8.3% of individuals, respectively.
Disclosure: The study authors reported no conflicts of interest.
