Dr Desai on the Role of Palbociclib in HR+, HER2+ Metastatic Breast Cancer

“The data are compelling—I certainly would consider adding palbociclib in the maintenance phase for patients who [have] both hormone receptor–positive and HER2-positive metastatic disease.”

Neelam Desai, MD, a breast medical oncologist and hematologist at the Atrium Health Levine Cancer Institute, discussed the role of palbociclib (Ibrance) plus anti-HER2 therapy and endocrine therapy (ET) in patients with hormone receptor (HR)–positive, HER2-positive metastatic breast cancer.

Data from the phase 3 AFT-38 PATINA trial (NCT02947685) are compelling, as the investigators concluded that the combination of palbociclib, anti-HER2 therapy, and ET could represent a new standard of care for patients with HR-positive, HER2-positive metastatic breast cancer, Desai began. Following these findings, she noted that this regimen could be one she considers as maintenance therapy for her patients with HR-positive, HER2-positive metastatic breast cancer.

At a data cutoff of October 15, 2024, patients (n = 518) were randomly assigned to either receive palbociclib plus trastuzumab (Herceptin) or pertuzumab (Perjeta) and ET (n = 261), or anti-HER2 therapy plus ET alone (n = 257). Of note, the final progression-free survival (PFS) analysis was performed after 262 events and 53 months of median follow-up. Data demonstrated that palbociclib plus anti-HER2 and ET significantly improved PFS (HR, 0.74; 95% CI, 0.58-0.94; 1-sided P = .0074). Notably, the median PFS was 44.3 months (95% CI, 32.4-60.9) vs 29.1 months (95% CI, 23.3-38.6) in the palbociclib and control arms, respectively. The confirmed objective response rate was 29.2% compared with 22.2% (P = .0458), with a clinical benefit rate of 89.3% vs 81.3% (2-sided P = .0106).

Adverse effects occurred most frequently in patients in the palbociclib arm, specifically grade 3 neutropenia (63.2%). More patients from the palbociclib arm also experienced grades 2 and 3 fatigue (grade 2, 22.9%; grade 3, 5.4%), stomatitis (17.2%; 4.2%), and diarrhea (25.4%; 11.1%).

Treatment with palbociclib was generally well-tolerated in the study, and there were no new safety signals, which demonstrated a potential option for the respective patient population, Desai concluded.