ATLANTA—For metastatic colorectal cancer, the benefits of maintenance therapy with 5-FU/leucovorin appear questionable, according to results of the OPTIMOX2 study, presented by Frederique Maindrault-Goebel, MD, of Saint Antoine Hospital, Paris, France, at the American Society of Clinical Oncology 42nd Annual Meeting (abstract 3504). In the randomized phase II trial, maintenance therapy with 5-FU/leucovorin prolonged progression-free survival but did not improve duration of disease control, as compared to stopping chemotherapy after FOLFOX7, the Groupe Cooperateur Multidisciplinaire en Oncologie investigators showed.

OPTIMOX2 randomized 202 patients with metastatic colorectal cancer to either chemotherapy with modified FOLFOX7 followed by a chemotherapy-free interval, then a reintroduction of FOLFOX7 as needed (the experimental arm), or to chemotherapy followed by maintenance therapy and reintroduction of FOLFOX7 in a "stop and go" strategy as used in the previous OPTIMOX1 trial. OPTIMOX1 found the oxaliplatin(Drug information on oxaliplatin) "stop and go" strategy to be as active as continuous treatment, but less toxic, Dr. Maindrault-Goebel said.

The modified FOLFOX7 regimen had a lower oxaliplatin dose than that used in OPTIMOX1 (100 vs 130 mg/m2) and a slightly higher dose of continuous infusion 5-FU (3,000 vs 2,400 mg/m2).

Both arms received six cycles of modified FOLFOX7 (oxaliplatin 100 mg/m2 and leucovorin 400 mg/m2 on day 1, then 5-FU 3,000 mg/m2 as a 46-hour continuous infusion, every 2 weeks).

The OPTIMOX1 strategy arm then received maintenance with a simplified regimen of leucovorin 400 mg/m2, followed by a 5-FU 400 mg/m2 bolus and 5-FU 3,000 mg/m2 46-hour infusion. Upon "baseline progression," patients in both arms received modified FOLFOX7 for six more cycles. Baseline progression was defined as regrowth of the tumor to its baseline size. At this point, or when patients became symptomatic, FOLFOX7 was reintroduced in both arms.

Study Results

The response rates to both regimens were equal, at 61%, with each arm achieving a 3% complete response rate. After a median follow-up of 70 weeks, however, progression-free survival was significantly longer in the OPTIMOX1 maintenance arm (8.7 months vs 6.9 months, P = .009). Similarly, more OPTIMOX1 patients remained progression free more than 6 and 12 months later.