SAN FRANCISCO—In advanced colorectal cancer, the combination of oxaliplatin(Drug information on oxaliplatin) (investigational) and irinotecan(Drug information on irinotecan) (Camptosar) is beneficial as a first-line therapy, according to phase II clinical trial results presented at the 37th Annual Meeting of the American Society of Clinical Oncology (abstract 538).
Preclinical evidence that oxaliplatin and irinotecan are synergistic in combination provided the rationale for the current trial, noted Werner Scheithauer, MD, Vienna University Medical School.
In this randomized, multicenter trial, the combination—oxaliplatin 85 mg/m² and irinotecan 175 mg/m², both given as a 2-hour infusion on days 1 and 15 every 4 weeks—was compared with raltitrexed (Tomudex, investigational in the US) 3 mg/m² every 3 weeks as a 15-minute infusion).
A total of 92 chemotherapy-naïve patients with measurable metastatic colorectal cancer were entered into the trial. When patients progressed, they were crossed over to second-line treatment with the other study regimen.
At the initial dose level, the oxaliplatin/irinotecan regimen caused severe adverse hematologic and gastrointestinal reactions in 10 of 20 patients, generally during the first two courses. Tolerance became acceptable after the irinotecan dose was reduced to 150 mg/m².
Objective complete responses were seen in 3 patients on the combination regimen (6.5%) and in none on raltitrexed. Partial responses were reported in 17 patients on the combination (37%) and in 9 (19.6%) on raltitrexed. Stable disease was seen in 15 (32.6%) and 16 (34.8), respectively, and progression in 9 (19.6%) and 17 (37.0%), with the remainder not evaluable.
The overall response rate for the oxaliplatin/irinotecan arm was 43.5% and for raltitrexed, 19.6%. Improvements in WHO performance scores for the patients on the combination (62% vs 29%) were also significant (P = .021).
