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 1000mg/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 (1000mg/m2 / 125 mg/m2) and afatinib (30mg) was established. In a cohort of 11 patients, the combination showed an acceptable safety profile.