Palbociclib plus fulvestrant as first-line therapy for patients with locally advanced, inoperable or metastatic HR+/HER2- breast cancer in Germany: Interim results of the INGE-B phase II study

Abstract

Purpose: In the PALOMA‐3 trial, palbociclib plus fulvestrant demonstrated a clinically meaningful improvement in overall survival compared with fulvestrant plus placebo in patients (pts) with hormone receptor‐positive (HR+), HER2‐negative (HER2‐) metastatic breast cancer who had relapsed or progressed on prior endocrine therapy (Turner NC et al., NEJM 2018). Detailed analyses for first‐line (1L) and later‐line (2L+) therapy are still limited. Methods: The prospective, multicenter phase 2 INGE‐B trial was designed to generate efficacy and safety data on the combination of palbociclib with aromatase inhibitors or fulvestrant (1L, 2L+). This pre‐planned interim analysis was conducted to evaluate data on pts receiving palbociclib plus fulvestrant as 1L or 2L+ therapy. The primary objective was the clinical benefit rate (CBR) in pts with measurable disease according to RECIST v1.1. Key secondary endpoints included the overall response rate (ORR), the CBR for all pts, and safety. Data were analyzed with descriptive statistics. Results: At the cut‐off date of the interim analysis (Dec 17, 2018), 124 pts have been recruited to receive palbociclib plus fulvestrant (1L: 57 pts; 2L+: 67 pts). Of those, 54 pts treated in 1L were evaluable. Median age was 69.5 years, 96.3% of pts had an ECOG performance score of 0 or 1. 31.5% (n=17) of pts had non‐measurable bone‐only disease. The CBR was 58% (n=21) for the 36 pts with measurable disease (RECIST v1.1) and 65% (n=35) for all pts (investigator assessment). Grade 3/4 adverse events experienced by at least 10% of pts were neutropenia (n=17, 31.5%) and leukopenia (n=8, 14.9%). Conclusions: This INGE‐B interim analysis showed for the first time a remarkable clinical benefit for palbociclib plus fulvestrant as first‐line therapy for pts with HR+/HER2‐advanced breast cancer. No new safety signals emerged.