Radiation Therapy Oncology Group 0247: a randomized Phase II study of neoadjuvant capecitabine and irinotecan or capecitabine and oxaliplatin with concurrent radiotherapy for patients with locally advanced rectal cancer.

Abstract

To evaluate the rate of pathologic complete response (pCR) and the toxicity of two neoadjuvant chemoradiotherapy (chemoRT) regimens for Stage T3-T4 rectal cancer in a randomized Phase II study. Patients with Stage T3 or T4 rectal cancer of <12 cm from the anal verge were randomized to preoperative RT (50.4 Gy in 1.8-Gy fractions) with concurrent capecitabine (1,200 mg/m(2)/d Mondays through Friday) and irinotecan (50 mg/m(2) weekly in four doses) (Arm 1) or concurrent capecitabine (1,650 mg/m(2)/d Monday through Friday) and oxaliplatin (50 mg/m(2) weekly in five doses) (Arm 2). Surgery was performed 4-8 weeks after chemoRT, and adjuvant chemotherapy 4-6 weeks after surgery. The primary endpoint was the pCR rate, requiring 48 evaluable patients per arm. A total of 146 patients were enrolled. The protocol chemotherapy was modified because of excessive gastrointestinal toxicity after treatment of 35 patients; 96 were assessed for the primary endpoint-the final regimen described above. The patient characteristics were similar for both arms. After chemoRT, the rate of tumor downstaging was 52% and 60% and the rate of nodal downstaging (excluding N0 patients) was 46% and 40%, for Arms 1 and 2, respectively. The pCR rate for Arm 1 was 10% and for Arm 2 was 21%. For Arm 1 and 2, the preoperative chemoRT rate of Grade 3-4 hematologic toxicity was 9% and 4% and the rate of Grade 3-4 nonhematologic toxicity was 26% and 27%, respectively. Preoperative chemoRT with capecitabine plus oxaliplatin for distal rectal cancer has significant clinical activity (10 of 48 pCRs) and acceptable toxicity. This regimen is currently being evaluated in a Phase III randomized trial (National Surgical Adjuvant Breast and Bowel Project R04).