Clinical Oncology NewsAdding Palbociclib to Endocrine Therapy Shows No Benefit in Study

According to the final results from the phase 3 PALLAS trial, palbociclib offers no benefit over endocrine therapy alone in women with early HR+ HER2- breast cancer. The primary endpoint — 4-year invasive DFS — was nearly equivalent in the test and control arms of the study. None of the secondary endpoints showed a significant difference either. There was a high rate of palbociclib discontinuation (42%), mostly due to grade 3 or 4 neutropenia. But even in those who completed the two-year planned course showed no benefit over endocrine therapy alone. The results were not just disappointing, but surprising given that CDK 4/6 inhibitors plus endocrine therapy is the standard of care for advanced breast cancer.