Phase II trial of irinotecan in combination with amifostine in patients with advanced colorectal carcinoma

BACKGROUND: Irinotecan is effective in patients with advanced colorectal carcinoma in both first-line and salvage settings but its use can be limited by serious side effects. Amifostine has been shown to reduce the incidence of cisplatin-induced cumulative renal toxicity in patients with advanced ovarian carcinoma and nonsmall cell lung carcinoma. In the current pilot Phase II trial, the authors examined the potential role of amifostine as a protective agent against irinotecan-induced diarrhea and myelosuppression and evaluated an every-2-weeks regimen as an alternative schedule for the administration of irinotecan in patients with previously treated metastatic colorectal carcinoma. METHODS: All patients received amifostine, 740 mg/m2, followed by irinotecan, 250 mg/m2, every 2 weeks. A 6-week cycle of chemotherapy (every 2 weeks for 3 treatments) was chosen to assess toxicity and response. The main objective of the current study was to evaluate the impact of amifostine on gastrointestinal and hematologic toxicity. RESULTS: A total of 22 patients entered the current study. Six of these 22 patients (27%) had WHO Common Toxicity Criteria Grade 3 or 4 diarrhea, including 2 patients (9%) with Grade 4 diarrhea. Eight of 22 patients (36.3%) developed Grade 3 or 4 neutropenia (Grade 4 in 4 of the 22 patients [18%]). Dose reduction was required in 25% of the treatment cycles. Five of the 22 patients (23%) withdrew from the trial due to amifostine toxicity. Of the 15 patients who were evaluable for response, 4 patients (26.6%) had achieved a partial response and 9 (60%) had stable disease as their best response.CONCLUSIONS: The combination of irinotecan with amifostine in patients with previously treated metastatic colorectal carcinoma did not appear to reduce irinotecan toxicity. Amifostine did not appear to interfere with the cytotoxic effect of irinotecan. The results of the current study did demonstrate efficacy and safety of the every-2-weeks irinotecan schedule that was comparable to other established regimens and these results support its feasibility as a reasonable alternative in this disease setting.