Cetuximab in combination with capecitabine, irinotecan, and radiotherapy for patients with locally advanced rectal cancer: results of a Phase II MARGIT trial.

Purpose: To evaluate the safety and efficacy of preoperative radiotherapy (RT) in combination with cetuximab, capecitabine, and irinotecan in patients with locally advanced rectal cancer.

Methods And Materials: Patients with rectal cancer (clinical stage T3/4 or N+) were scheduled to receive cetuximab (400 mg/m(2) Day 1, 250 mg/m(2) Days 8, 15, 22, 29) in combination with weekly irinotecan 40 mg/m(2) and capecitabine 500 mg/m(2) twice daily (Days 1-38). RT was given to a dose of 50.4 Gy (45 + 5.4 Gy). Primary endpoint was toxicity, and antitumor activity as assessed by the pathologic complete remission (pCR) rate was a secondary endpoint.

Results: Fifty patients were enrolled; 88% showed T3 or T4 and 76% nodal-positive tumors with a median distance from the anal verge of 7.5 cm. The actual dose intensity was as follows (median/mean, %): cetuximab 100/92, irinotecan 100/91, capecitabine 100/89). Main adverse events Grades 2/3/4 were (National Cancer Institute common toxicity criteria version 3.0, %): leukocytopenia 6/2/2, nausea/vomiting 4/2/0, diarrhea 34/30/0, proctitis 26/2/0, elevation of liver transaminases 8/10/0, and acnelike skin rash 46/6/0. All patients underwent surgery, and no postoperative deaths occurred. Eighty-four percent underwent low-anterior resection, and 68% of the specimen exhibited moderate or good tumor regression, but only 4 patients had a pCR.

Conclusion: Preoperative chemoradiation with cetuximab-CapIri-RT has manageable toxicity, with diarrhea being the most commonly observed adverse event. Nevertheless, the efficacy of this regimen with a pCR rate of only 8% was significantly lower than that observed in a previous Phase I trial.