Phase I Clinical Trial to Determine the Feasibility and Maximum Tolerated Dose of Panitumumab to Standard Gemcitabine-Based Chemoradiation in Locally Advanced Pancreatic Cancer.

Purpose: Epidermal growth factor receptor (EGFR) inhibitors may improve both the therapeutic efficacy of radiotherapy and the radiosensitizing activity of gemcitabine. Based on this rationale and the nonoverlapping toxicity profiles of gemcitabine and the monoclonal EGFR antibody panitumumab, we designed a phase I trial to investigate the maximum-tolerated dose (MTD), safety, and activity of panitumumab added to gemcitabine-based chemoradiotherapy (CRT) in patients with locally advanced pancreatic cancer (LAPC).

Experimental Design: Patients with LAPC and WHO performance status 0 to 1 were treated with weekly panitumumab at four dose levels (1-2.5 mg/kg), combined with weekly gemcitabine 300 mg/m(2) and radiotherapy (50.4 Gy in 28 fractions) for 6 weeks, followed by gemcitabine 1,000 mg/m(2) weekly for 3 weeks every 4 weeks until disease progression or unacceptable toxicity. Each cohort was monitored during the combination therapy to establish dose limiting toxicity. Tumor evaluation was performed after CRT and during gemcitabine monotherapy.

Results: Fourteen patients were enrolled; 14 were evaluable for toxicity and 13 for response. The MTD for panitumumab was 1.5 mg/kg. Three of the 6 patients, treated at MTD, experienced grade 3 adverse events during the combination therapy; neutropenia (n = 2; 33%), fatigue (n = 1; 17%), nausea (n = 1; 17%), and vomiting (n = 1; 17%). Partial response was achieved by 3 patients (23%), 1 in each dose cohort. Median progression free survival of the three cohorts together was 8.9 months.

Conclusions: The addition of panitumumab to gemcitabine-based chemoradiotherapy in LAPC has manageable toxicity and potential clinical efficacy.