The efficacy of oxaliplatin in combination with fluorouracil (FU)/leucovorin (LV) was evaluated in a North American, multicenter, open-label, randomized, active-controlled trial (A Randomized Phase III Trial of Three Different Regimens of CPT-11 Plus 5-Fluorouracil and Leucovorin Compared to 5-Fluorouracil and Leucovorin in Patients with Advanced Adenocarcinoma of the Colon and Rectum; NCT00003594). The trial included 7 arms at different times during its conduct, four of which were closed due to either changes in the standard of care, toxicity, or simplification. During the trial, the control arm was changed to irinotecan with fluorouracil/leucovorin.

The results reported below compared the efficacy of oxaliplatin with fluorouracil/leucovorin and oxaliplatin with irinotecan to an approved control regimen of irinotecan with fluorouracil/leucovorin in 795 concurrently randomized patients previously untreated for locally advanced or metastatic colorectal cancer. Table 19 presents the dosing regimens for the three arms. After completion of enrollment, the dose of irinotecan with fluorouracil/leucovorin was decreased due to toxicity.

Eligible patients were at least 18 years of age; had known locally advanced, locally recurrent, or metastatic colorectal adenocarcinoma not curable by surgery or amenable to radiation therapy; with an Eastern Cooperative Oncology Group (ECOG) performance status ≤0, 1, or 2. Patients had to have absolute neutrophil count (ANC) greater than or equal to 1.5 × 109/L, platelets greater than or equal to 100 × 109/L, hemoglobin greater than or equal to 9.0 g/dL, creatinine less than or equal to 1.5 × upper limit of normal (ULN), total bilirubin less than or equal to 1.5 mg/dL, aspartate transaminase (AST) less than or equal to 5 × ULN, and alkaline phosphatase less than or equal to 5 × ULN. Patients may have received adjuvant treatment for resected Stage II or III disease without recurrence within 12 months. Randomization was stratified by ECOG performance status (0, 1 vs 2), prior adjuvant chemotherapy (yes vs no), prior immunotherapy (yes vs no), and age (less than 65 vs greater than or equal to 65 years). Although no post study treatment was specified in the protocol, 65% to 72% of patients received additional post study chemotherapy after study treatment discontinuation on all arms. Fifty-eight percent of patients on the oxaliplatin with fluorouracil/leucovorin arm received an irinotecan-containing regimen and 23% of patients on the irinotecan with fluorouracil/leucovorin arm received an oxaliplatin-containing regimen. The main efficacy outcome measure was 3-year disease-free survival (DFS) and additional efficacy outcome measures were overall survival (OS).

Table 20 presents the baseline characteristics.

The median number of cycles administered per patient was 10 (23.9 weeks) for the oxaliplatin plus fluorouracil/leucovorin regimen, 4 (23.6 weeks) for the irinotecan plus fluorouracil/leucovorin regimen, and 7 (21.0 weeks) for the oxaliplatin plus irinotecan regimen.

Patients who received oxaliplatin with fluorouracil/leucovorin had a significantly longer time to tumor progression based on investigator assessment, longer OS, and a significantly higher confirmed response rate based on investigator assessment compared to patients who received irinotecan with fluorouracil/leucovorin. Efficacy results are summarized in Table 21 and Figure 3.

Figure 3: Kaplan-Meier Curves for Overall Survival in Previously Untreated Advanced Colorectal Cancer Trial

In descriptive subgroup analyses, the improvement in overall survival (OS) for oxaliplatin with fluorouracil/leucovorin compared to irinotecan with fluorouracil/leucovorin appeared to be maintained across age groups, prior adjuvant treatment, number of organs involved and both sexes; however, the effect appeared larger among women than men.