Gemcitabine and nab-paclitaxel combined with afatinib in metastatic pancreatic cancer – Results of a phase 1b clinical trial

Purpose: The combination of gemcitabine/nab-paclitaxel is an established standard treatment in the first-line treatment of metastatic ductal adenocarcinoma of the pancreas (mPDAC). Afatinib, an oral second-generation pan ErbB family tyrosine kinase inhibitor, has shown promising pre-clinical signs in the treatment of pancreatic cancer. The aim of this phase 1b trial was to determine the maximum tolerated dose (MTD) of afatinib in combination with gemcitabine/nab-paclitaxel in patients with mPDAC. Methods: Treatment naïve patients (≥18 years) with histologically proven mPDAC and good performance status (ECOG 0/1) were enrolled to receive gemcitabine/nab-paclitaxel in combination with afatinib. Treatment was continued until disease progression, or unacceptable toxicity. The primary endpoint MTD was determined using a 3 + 3 design. Treatment started at dose level 0 with intravenous gemcitabine/nab-paclitaxel 1000 mg/m² / 125 mg/m² (day 1, 8, 15 of a 28-day cycle) + oral afatinib 30 mg daily. At dose level + 1 afatinib was increased to 40 mg. Secondary endpoints included safety parameters and exploratory endpoints evaluated treatment efficacy. Results: Twelve patients were included in this trial, and 11 patients were treated and analysed in the safety and full analysis set (FAS). At dose level 0 the first three patients did not experience a dose-limiting toxicity (DLT). At dose leve (DL) + 1 two patients experienced a DLT. Accordingly, enrolment continued at DL 0 with three more patients, of which one experienced DLT (skin rash ≥ CTCAE grade 3). Seven patients (63.6%) experienced at least one treatment-emergent serious adverse event (TESAE), with four patients (36.4%) experiencing TESAEs grade 3–5 related to the study medication. In the FAS, the objective response rate (ORR) was 36.4%, median progression-free survival (PFS) was 3.5 months and median overall survival in nine evaluable patients was 7.5 months. Conclusions: In this phase 1b clinical trial, the MTD of gemcitabine/nab-paclitaxel (1000 mg/m² / 125 mg/m²) and afatinib (30 mg) was established. In a cohort of 11 patients, the combination showed an acceptable safety profile.