Large-Scale, Prospective Observational Study of Regorafenib in Japanese Patients with Metastatic Colorectal Cancer in a Real-World Clinical Setting

Background Regorafenib improved the overall survival (OS) of patients with metastatic colorectal cancer (mCRC) who progress after standard therapies in two phase III trials. The present large-scale prospective observational study evaluated the safety and effectiveness of regorafenib administered to Japanese patients with mCRC in real-life setting. Materials and Methods Patients with mCRC were prospectively registered and initially received <= 160 mg oral regorafenib daily, at the investigator's discretion, for weeks 1-3 of each 4-week cycle. The study's primary aim was to assess safety, particularly unexpected clinically significant adverse drug reactions (ADRs). A Cox's proportional hazards model was used to evaluate the association between OS, hand-foot skin reaction (HFSR), and baseline characteristics. Results We evaluated 1,227 of 1,301 patients (enrolled from March 2013 to May 2015). ADRs occurred in 89.3% of patients (mostly within the first 4 weeks) and were a major reason for discontinuing treatment. The most frequent ADRs were HFSR, liver injury, and hypertension. The cumulative incidence of HFSR and liver injury was higher in patients who initially received 160 mg than in those who received <= 120 mg. The incidence of hypertension and fatigue was similar between groups. Median OS was 6.9 months (95% confidential interval, 6.4-7.4). OS was associated with early onset of HFSR and good performance status (PS) but not with the initial dose. Conclusion The outcomes of this study were consistent with those of clinical trials. There were no new safety concerns. Regorafenib treatment would not be recommended for patients with higher PS. Implications for Practice Previous clinical trials demonstrated regorafenib improved overall survival in patients with metastatic colorectal cancer who progress after standard chemotherapies. Because the eligibility criteria of the trials were restricted compared with a real-world setting, the data from the trials may not fully represent the profiles of regorafenib in clinical practice. This large-scale observational study showed that the safety and effectiveness of regorafenib in clinical practice were generally consistent with previous trials. The majority of patients reported adverse drug reactions within the first 4 weeks, most commonly hand-foot skin reaction. Regorafenib treatment would not be recommended for patients with higher performance status.