Switching from FOLFIRI Plus Cetuximab to FOLFIRI Plus Bevacizumab Based on Early Tumor Shrinkage in RAS Wild-Type Metastatic Colorectal Cancer: A Phase II Trial (HYBRID)

Background: Long-term anti-EGFR antibody treatment increases the risk of severe dermatologic toxicities. This single-arm, phase II trial aimed to investigate the strategy of switching from cetuximab to bevacizumab in combination with FOLFIRI based on early tumor shrinkage (ETS) in patients with RAS wild-type metastatic colorectal cancer (mCRC). Methods: Radiologic assessment was performed to evaluate ETS, defined as >= 20% reduction in the sum of the largest diameters of target lesions 8 weeks after the introduction of FOLFIRI plus cetuximab. ETS-negative patients switched to FOLFIRI plus bevacizumab, whereas ETS-positive patients continued FOLFIRI plus cetuximab for eight more weeks, with a switch to FOLFIRI plus bevacizumab thereafter. The primary endpoint was progression-free survival. Results: This trial was prematurely terminated due to poor accrual after a total enrollment of 30 patients. In 29 eligible patients, 7 were ETS-negative and 22 were ETS-positive. Two ETS-negative patients and 17 ETS-positive patients switched to FOLFIRI plus bevacizumab 8 weeks and 16 weeks after initial FOLFIRI plus cetuximab, respectively. Median progression-free and overall survival durations were 13.4 and 34.7 months, respectively. Six (20%) patients experienced grade >= 3 paronychia, which improved to grade <= 2 by 18 weeks. Grade >= 3 acneiform rash, dry skin, and pruritus were not observed in any patients. Conclusions: Our novel treatment strategy delivered acceptable survival outcomes and reduced severe dermatologic toxicities.