Phase III study of gemcitabine [G] plus cetuximab [C] versus gemcitabine in patients [pts] with locally advanced or metastatic pancreatic adenocarcinoma [PC]: SWOG S0205 study

Abstract

LBA4509 Background: Epidermal growth factor receptor [EGFR] pathway is a rational target for therapeutic intervention. This study tested the efficacy of an anti-EGFR monoclonal antibody and gemcitabine [G] combination in the Phase III setting in patients with advanced PC. Methods: Eligibility included locally advanced unresectable or metastatic PC; adequacy of organ function; performance status (PS) 0- 2; no prior EGFR therapy; no prior systemic chemotherapy except for adjuvant chemotherapy; and submission of tumor for EGFR immunostaining. The primary endpoint was overall survival. Secondary endpoints included objective response, time to progression, pain control, and quality of life. Assuming 6 months median survival, the study was designed to detect a median improvement to 8 months (1.33 hazard ratio) with 90% power, based on a one-sided 0.0125 test, and 704 eligible patients. Primary analyses used a Cox regression model, stratified for factors used in the randomization. Patients were stratified by PS, stageand prior pancreatectomy, and randomized to either G alone or G plus C. G was given at a dose of 1,000 mg/m2/wk for seven weeks out of 8, then 3 weeks on and one week off. C was given as a loading dose of 400 mg/m2 on week 1 and then 250 mg/m2 weekly. Results: 766 pts (735 eligible) with a median age of 64 (30–91) were enrolled by SWOG and CTSU between January 2004 and April 2006. Of those, 51% were males, 21.5% had locally advanced disease, and 13% had PS of 2. The study closed with full accrual. The median survival was 6 months in the G arm and 6.5 months in the G plus C arm for an overall HR of 1.09 (95% CI 0.93–1.27, p= 0.14) . The corresponding PFS was 3 months and 3.5 months, for G and G+C arms, respectively (HR =1.13, 95%CI .97–1.3, p=.058). The confirmed response probabilities were 7 % in each arm, and inclusion of unconfirmed responses yielded 14% in the G arm and 12% in the G + C arm.702 pts were evaluable for toxicity. 90 pts experienced at least one grade 4 toxicity; 14% on the G plus C, 11% on G alone. Conclusions: This study failed to demonstrate a clinically significant advantage of the addition of cetuximab to gemcitabine for overall survival, PFS and response in advanced PC. No significant financial relationships to disclose.