LAUSR

AIM To compare the cost of biweekly regimens of first-line (1L) treatments of cetuximab-FOLFIRI versus panitumumab-FOLFOX in patients with Kirsten's rat sarcoma wild type (KRAS WT) metastatic colorectal cancer (mCRC) in the US, across varying weights and body surface areas (BSAs). MATERIALS AND METHODS Cost-minimization analysis (CMA) was performed to estimate per-patient cost differences of cetuximab-FOLFIRI versus panitumumab-FOLFOX. The CMA estimated the costs of rat sarcoma (RAS) testing, premedication, drug acquisition, treating infusion reactions (IRs), supportive therapy, and biweekly administration of chemotherapy, cetuximab (500 mg/m2), and panitumumab (6 mg/kg) over 43 weeks (median progression-free survival). To calculate dose and cost, weight and height data were gathered from an electronic health record-derived de-identified database (n = 7,669; January 2013-October 2020). Base case analysis utilized mean weight/BSA of the overall cohort (82.04 kg/1.92 m2), and alternate scenarios were based on 88.18 kg/2.03 m2 (men, n = 4,477) and 73.43 kg/1.76 m2 (women, n = 3,192). RESULTS For the base case, total treatment costs were $167,853 for cetuximab-FOLFIRI and $168,254 for panitumumab-FOLFOX; cost savings per patient receiving cetuximab-FOLFIRI was $400. Cost savings in alternate scenarios (men, $15,138; women, $15,004) resulted from lower drug acquisition costs for cetuximab (men, $14,833; women $14,854) and administration cost ($440) versus panitumumab. Cost savings of cetuximab-FOLFIRI in treating IR ($353) were similar across all scenarios. LIMITATIONS With no head-to-head clinical trial data in the 1L setting, assumptions of similarity in efficacy and safety of cetuximab versus panitumumab was based on published network meta-analysis and the ASPECCT trial. This model did not consider a lifetime horizon. Costs of managing all adverse events (except IR) were not included. CONCLUSIONS Biweekly cetuximab-FOLFIRI offers cost savings compared with panitumumab-FOLFOX for 1L therapy of patients with KRAS WT mCRC in the US. These cost differences were observed for the overall population and across different BSA and weights for men and women.