Palbociclib in combination with either aromatase inhibitors or fulvestrant for patients with advanced HR+/HER2- breast cancer in Germany - Final results of the phase 2 multicohort INGE-B trial.

Introduction The INGE-B trial (NCT02894398) aimed to confirm the efficacy and safety data from the PALOMA trials for patients treated first line (1L) with palbociclib (PAL) and letrozole or 1L and later line with PAL and fulvestrant. In addition, efficacy and safety on the combination of PAL with anastrozole, exemestane (1L), or letrozole (later line) was investigated. Methods The prospective, multicenter, multi-cohort phase 2 trial INGE-B enrolled adult patients with locally advanced, inoperable, or metastatic HR+/HER2- breast cancer in Germany. The primary endpoint was the clinical benefit rate (CBR) in patients with measurable disease according to RECIST v1.1. Secondary endpoints were overall response rate (ORR), progression free survival (PFS), overall survival (OS), safety and quality of life. Data were analyzed with descriptive statistics. Results Between 2016 and 2018, 388 patients were enrolled at 64 German sites. Among patients with measurable disease treated with PAL in 1L (n=157), the CBR was 63.7% (100/157). Among all patients treated with PAL 1L (n=219), PFS was 20.1 months (95% CI 14.6 - 24.0) and OS was 40.9 months (95% CI 35.1-49.2). The most common grade 3/4 adverse event was neutropenia (33.4% n=77). There were no treatment-related deaths. Conclusion The INGE-B trial demonstrated good efficacy and tolerability of PAL with letrozole (1L) or fulvestrant (first and later line) in accordance with the PALOMA-trials. In addition, the so far lacking proof of efficacy and safety of PAL in combination with anastrozole or exemestane in 1L and with letrozole in later line was provided by INGE-B.