Background: Cetuximab (CET) 250 mg/m² weekly (q1w) after an initial dose of 400 mg/m² added to chemotherapy (CT) is licensed for treatment of (K)RAS wild-type metastatic colorectal cancer (mCRC). In practice, administration of CET 500 mg/m² plus CT every 2 weeks (q2w) is common. We compared healthcare costs between q2w and q1w regimens in a US claims database study. Methods: A cohort of 2,943 mCRC patients CET-treated between 2010 and 2016, identified in IBM MarketScan, was analyzed for costs associated with CET+CT q2w vs q1w. All-category costs (ACC), stratified by overall outpatient (OO), inpatient (OI), and pharmacy (OP) claimed costs during the exposure period, were compared between groups. Additionally, subcategories of CRC- and skin toxicity (ST)–related claims were explored, and imputation of capitated claim costs was performed. Patients were weighted by the stabilized inverse probability of treatment (IPTW) based on a high-dimensional propensity score to control for confounding. Generalized linear models (GLMs) with gamma distributions were used to compare regimens. Inflation-adjusted costs (2016 US dollars) are presented per patient per month ($PPPM) with 95% CIs. Results: 1,779 and 951 patients were classified as q1w and q2w, respectively. Median ACC were 14,089 (q2w) vs 14,034 (q1w) $PPPM. Mean ACC and OO, OI, and OP costs are summarized in the table. CIs overlapped in each category, with GLMs showing no statistically significant differences. This finding was similar for CRC and ST subcategories. Conclusions: No cost differences were found between q2w and q1w regimens. In line with published noninferiority of overall survival with the q2w regimen, it represents an effective, cost-neutral option for treating mCRC patients.

^a Two-sided test for difference in mean IPTW costs from the GLM with a 5% type I error rate.