KEY TAKEAWAYS
- The PATRICIA II phase 2 trial aimed to compare palbociclib + T + ET with TPC in HER2+ HR+ PAM50 Luminal ABC.
- The primary endpoint was to determine PFS.
- Researchers observed that the palbociclib combo demonstrates superior PFS over TPC in HER2+ luminal ABC.
The PATRICIA trial (cohort A-B) demonstrated that palbociclib plus trastuzumab (T) is safe and active in patients (pts) with T-pretreated HER2-positive Hormone Receptor-positive (HR+/HER2+) PAM50 Luminal advanced breast cancer (ABC).
Eva Ciruelos and the team aimed to present the primary efficacy analysis of the randomized cohort C from the PATRICIA trial that compares the efficacy of palbociclib + T + endocrine therapy (ET) with the treatment of physicians’ choice (TPC).
They performed an inclusive analysis of PATRICIA (cohort C), a randomized, open-label, phase II study conducted in Spain from August 2019 to August 2023. Patients with HER2+/HR+ and centrally tested PAM50 Luminal A or B intrinsic subtype ABC, previously treated with at least 1 anti-HER2 regimen, were eligible.
Patients were randomized 1:1 to Cohort C1 (Palbociclib 125 mg/day orally 3 weeks/1 week off + T + ET) or Cohort C2 (TPC, including T + any ET or chemotherapy (CT) + T, or T-DM1). Stratification factors included prior regimens for ABC and the presence of visceral disease. The primary endpoint was progression-free survival (PFS). The trial aimed to recruit 102 patients, with an 80% power to detect an HR of 0.62 favoring the palbociclib cohort, but was closed after randomizing 73 patients due to slow recruitment.
About 264 patients were pre-screened, and 73 were randomized. Baseline patient characteristics were summarized. In cohort C1, 50% received fulvestrant and 50% aromatase inhibitor as ET. In cohort C2, 37.1% were treated with TDM-1, 45.7% with CT+ T, 11.4% with ET + T, and 2 withdrew consent before treatment.
Palbociclib + T + ET showed longer PFS compared to TPC (median 9.1 vs. 7.5 months, stratified HR=0.52 [95%CI 0.29-0.94]; P=0.031); 12-months PFS rates were 43.7% and 21.4%, respectively. ORR was 18.9% (95% CI 8.6-35.7) in C1 and 8.3% (95% CI 1.4-28.5) in C2. Grade ≥3 adverse events occurred in 63.2% of C1 and 45.5% of C2. The most frequent grade ≥3 adverse event in the experimental arm was neutropenia (55.3%).
The study concluded that the combination of palbociclib, trastuzumab, and ET demonstrated a statistically significant improvement in PFS for patients with previously treated PAM50 luminal A or B HER2+ ABC compared to the treatment of physicians’ choice.
The trial was sponsored by the SOLTI Breast Cancer Research Group.
Source: https://meetings.asco.org/abstracts-presentations/233645
Clinical Trial: https://clinicaltrials.gov/study/NCT02448420
Ciruelos E, Pascual T, Villacampa G, et al. (2024). “Primary results from PATRICIA cohort C (SOLTI-1303), a randomized phase II study evaluating palbociclib with trastuzumab and endocrine therapy in pretreated HER2-positive and PAM50 luminal advanced breast cancer.” Presented at ASCO 2024. J Clin Oncol 42, 2024 (suppl 16; abstr 1008), 10.1200/JCO.2024.42.16_suppl.1008
