Regorafenib in Patients with Antiangiogenic-Naive and Chemotherapy-Refractory Advanced Colorectal Cancer: Results from a Phase IIb Trial

Background Regorafenib is a multikinase inhibitor with antiangiogenic effects that improves overall survival (OS) in metastatic colorectal cancer (mCRC) after failure of standard therapies. We investigated the efficacy and safety of regorafenib in antiangiogenic therapy-naive chemotherapy-refractory advanced colorectal cancer. Patients and Methods This single-center, single-arm, phase IIb study (NCT02465502) enrolled adults with mCRC whose disease had progressed on, or who were intolerant to, standard therapy, but who were antiangiogenic therapy-naive. Patients received regorafenib 160 mg once daily for 3 weeks per 4-week cycle. The primary endpoint was progression-free survival (PFS) rate at week 8. Results Of 59 treated patients, almost half had received at least four prior lines of therapy. Patients received a median of 86% of the planned dose. The week 8 PFS rate was 53% (95% confidence interval [CI], 39.1-64.3); median PFS was 3.5 months (95% CI, 1.8-3.6). Median OS was 7.4 months (95% CI, 5.3-8.9). Tumor response (RECIST version 1.1) was 2%, and metabolic response rate (criteria from the European Organisation for Research and Treatment of Cancer) was 41%. The most frequently reported regorafenib-related grade >= 3 adverse events were hypertension (36%), hand-foot skin reaction (HFSR, 25%), and hypophosphatemia (24%). There were no regorafenib-related deaths. An exploratory analysis showed that patients with grade >= 2 HFSR had longer OS (10.2 months) with regorafenib treatment versus those with grades 0-1 (5.4 months). Conclusion These findings support the antitumor activity of regorafenib in antiangiogenic-naive patients with chemotherapy-refractory mCRC. Implications for Practice The multikinase inhibitor regorafenib improved overall survival in the phase III CORRECT and CONCUR trials in heavily pretreated patients with treatment-refractory metastatic colorectal cancer (mCRC). Exploratory subgroup analysis from CONCUR suggested that regorafenib treatment prior to targeted therapy (including bevacizumab) may improve outcomes. In this single-center, single-arm phase IIb study, regorafenib demonstrated antitumor activity in 59 antiangiogenic-naive patients with chemotherapy-refractory mCRC. Further studies should assess the efficacy of regorafenib in this patient population, as well as explore the reasons behind improved outcomes among patients who had a metabolic response and those who developed hand-foot skin reaction.