Irinotecan associated with cetuximab given every 2 weeks versus cetuximab weekly in metastatic colorectal cancer

The aim of the present study was to compare the efficacy and safety of weekly versus an every 2-week administration of cetuximab in association with irinotecan in patients with metastatic colorectal cancer (MCRC).

We reviewed the clinical records of 50 patients with MCRC who began treatment with cetuximab from February 2004 to January 2007. Two different treatment schedules were used. In the first group (N = 32), cetuximab was given at an initial dose of 400 mg/m2, followed by weekly infusions of 250 mg/m2. In the second group (N = 18), cetuximab was administered every 2 weeks at a dose of 500 mg/m2. The two groups were compared for tumor response, time to progression (TTP), overall survival (OS), and toxicity.

All patients had received irinotecan and 5-fluorouracil; a majority had previously received oxaliplatin. Disease control (partial response + stable disease) was achieved in 56.3% of patients receiving weekly cetuximab versus 77.8% in the other group (P = 0.21). The median follow-up for all patients was 34.2 months. TTP (Group 1: 28% vs. Group 2: 18%, P = 0.9356) and OS (Group 1: 75% vs. Group 2: 72%, P = 0.6748) rates at 7 months were similar in the two groups. Skin toxicity was the most relevant adverse event: 78.1% of the patients had acne-like rash in the first group and 61% in the second group. However, only one patient in each group had a grade 3 toxic reaction.

There is no major difference of efficacy and safety between cetuximab given every 2 weeks and a weekly dosing regimen, in association with irinotecan.