SAN FRANCISCOIn advanced colorectal cancer, the combination of
oxaliplatin (investigational) and 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
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 combinationoxaliplatin 85
mg/m² and irinotecan 175 mg/m², both given as a 2-hour infusion on days 1 and
15 every 4 weekswas 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
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).