Sex and Regorafenib Toxicity in Refractory Colorectal Cancer: Safety Analysis of the RegARd-C Trial

Predictive factors for adverse events in metastatic colorectal cancer patients treated with regorafenib are currently lacking. In this safety analysis of a prospective phase II clinical trial, we assess the association between several clinical, laboratory, and imaging parameters and the occurrence of adverse events. Our results show that female sex is an independent risk factor for increased toxicity. Background: Regorafenib is a standard treatment for refractory metastatic colorectal cancer (mCRC). In view of the toxicity burden, significant research efforts have been made to increase the therapeutic ratio of this multikinase inhibitor. Predictive factors for treatment-related adverse events (TRAEs), however, are still lacking. Materials and Methods: We assessed the association between a number of baseline clinical, laboratory and imaging parameters and the occurrence of TRAEs in 136 patients who had received regorafenib (160 mg/day, 3-weeks-on/1-week-off) in a prospective phase II clinical trial. Results: Grade >= 2 TRAEs during the first cycle of treatment (84% vs. 60%, P=.002) and grade >= 3 TRAEs throughout the whole treatment (71% vs. 53%, P=.035) occurred more frequently in females, with sex being the only independent predictive factor of early and any-time toxicity (OR 3.4; 95% CI: 1.2-11.1, P=.02 and OR 2.1; 95% CI: 1.0-4.4, P=.045, respectively). Fatigue, anorexia, hypertension, and rash were reported significantly more frequently by females than males (P <.04). Females were also more likely to suffer early (19% vs. 5%, P=.014) and any-time serious AEs (28% vs. 9%, P=.005), and to require early dose modifications (55% vs. 37%, P=.055). Conclusion: This is the first study showing an association between sex and TRAEs during regorafenib treatment for mCRC. If confirmed in larger, independent series, these results could pave the way for the implementation of personalized regorafenib dosing strategies with the potential to optimize oncological outcomes while reducing toxicity and preserving quality of life. (C) 2021 Elsevier Inc. All rights reserved.