EXPERT-C: A randomized phase II European multicenter trial of neoadjuvant chemotherapy (capecitabine/oxaliplatin) and chemoradiation (CRT) with or without cetuximab followed by total mesorectal excision (TME) in patients with MRI-defined high-risk rectal cancer.

Abstract

360 Background: We previously demonstrated the feasibility of administering neoadjuvant chemotherapy before CRT and TME in patients with MRI selected poor prognosis rectal cancer (Chua Y J et al Lancet Oncol 2010). This trial evaluates the addition of the anti-EGFR antibody cetuximab to this treatment strategy. KRAS and BRAF mutations have been established as predictive for lack of response to anti-EGFR therapy in metastatic colorectal cancer. Methods: Patients with newly diagnosed, histologically confirmed, MRI defined high risk rectal adenocarcinoma were randomised to receive 4 cycles of capecitabine 1,700mg/m2 with oxaliplatin 130mg/m2 (CAPOX) followed by CRT, 45Gy/25# + 5.4Gy/3# boost with concurrent continuous capecitabine 1,650mg/m2/day, TME and 4 cycles of adjuvant CAPOX (EXPERT) or the same regimen with the addition of cetuximab (400mg/m2 loading dose week 1, followed by 250mg/m2/week) (EXPERT-C). The primary endpoint is complete response (CR) (defined as pathological complete response or radiological complete response in patients who decline surgery) in KRAS and BRAF wild type tumours. Secondary endpoints include radiological response to CRT, CR in both KRAS wild type and mutant patients, R0 resection rates, progression free and overall survival and safety. Results: Between 2005-2008, 165 eligible patients were recruited from 15 centres (EXPERT n=81, EXPERT-C n=84). 99% of patients had performance status 0-1, 98% had ≥ T3 disease, 56% had an involved or threatened circumferential resection margin and 72% had evidence of extramural venous invasion determined by MRI. The current median follow up is 30 months. 72/81 (89%) and 79/84 (94%) of patients completed neoadjuvant CRT and 72/81 (89%) and 77/84 (92%) patients underwent curative-intent surgery on the EXPERT and EXPERT-C arms respectively. Two patients declined surgery. Conclusions: The primary and secondary endpoints will be analyzed in October 2010 and will be presented at the meeting. [Table: see text]