Palbociclib-Based Therapy for HER2-Positive and PAM50 Luminal Advanced Breast Cancer

By: Jenna Carter, PhD
Posted: Tuesday, July 9, 2024

Efficacy findings from the Cohort C of the PATRICIA trial were recently presented at the 2024 of the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1008). Eva Ciruelos, PhD, of Hospital Universitario 12 de Octubre, Madrid, and colleagues presented the primary efficacy results with the CDK4/6 inhibitor palbociclib plus trastuzumab and endocrine therapy in patients with pretreated HER2-positive and PAM50 luminal advanced breast cancer. The investigational combination treatment led to improved progression-free survival compared with treatment of physician’s choice in this patient population.

A total of 264 patients were prescreened for inclusion in this randomized, open-label, phase II study between August 2019 to August 2023. The study was conducted at 34 sites in Spain. Eligible patients included those with HER2-positive, hormone receptor–positive, and centrally tested PAM50 luminal A or B intrinsic subtype advanced breast cancer who received at least one prior line of anti-HER2–based regimens. Patients were randomly assigned on a 1:1 basis to cohort C1 (palbociclib plus trastuzumab and endocrine therapy) or cohort C2 (treatment of physician’s choice, including trastuzumab plus any endocrine therapy or chemotherapy plus trastuzumab, or ado-trastuzumab emtansine). However, the study was closed because of slow recruitment after 73 patients were randomly assigned.

Findings revealed that the investigational combination was associated with longer progression-free survival compared with treatment of physician’s choice (median 9.1 vs 7.5 months, stratified hazard ratio [HR] = 0.52, 95% confidence interval [CI] = 0.29–0.94, two-sided P = .031); the 12-month progression-free survival rates were 43.7% and 21.4%, respectively. Additionally, the overall response rate was 18.9% (95% CI = 8.6–35.7) in cohort C1 and 8.3% (95% CI = 1.4–28.5) in cohort C2.

Disclosure: For full disclosures of the study authors, visit coi.asco.org.

2024 ASCO Annual Meeting

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