- A phase 2 trial of patients in Japan showed that first-line palbociclib-letrozole treatment for hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2−) advanced breast cancer (ABC) is safe and effective, with PFS probability at 1 year of 75.6%.
Why this matters
- Japanese patients were not included in the PALOMA-1 clinical trial, the first major clinical trial to evaluate palbociclib-letrozole for ABC.
- Phase 2 multicenter, open-label, single-group clinical trial of 42 patients.
- Primary outcome: probability of 1-year PFS.
- Health-related quality of life evaluated by Functional Assessment of Cancer Therapy-Breast and Trial Outcome Index.
- Funding: Pfizer Inc.
- Median duration of treatment, 33.0 (range, 1.8-49.2) months.
- Probability of PFS at 1 year, 75.6% (90% CI, 62.4%-84.7%).
- Median PFS was 35.7 (95% CI, 21.7-46.7) months.
- Objective response rate: 47.6% (95% CI, 32.0%-63.6%).
- Disease control rate: 85.7% (95% CI, 71.5%-94.6%).
- Most common treatment-related adverse events (all grades; grades 3/4):
- Neutropenia (100.0%; 92.9%).
- Leukopenia (83.3%; 59.5%).
- Stomatitis (76.2%; 0%).
- Health-related QoL was stable throughout the trial, with no clinically meaningful deterioration.
- Single-group, open-label design.