The multitargeted kinase inhibitor regorafenib improved overall survival (OS) and progression-free survival (PFS) and achieved superior disease control in patients with metastatic colorectal cancer (mCRC) who progressed on all standard therapy. These results of the international, phase 3, randomized, double-blind, placebo-controlled, multicenter CORRECT trial were presented at the American Society of Clinical Oncology Gastrointestinal Symposium in San Francisco, California. “Regorafenib increases overall survival versus placebo in patients with mCRC who have exhausted other treatment options. This is the first small-molecule multikinase inhibitor with proof of efficacy in colorectal cancer, and it is a potential new standard of care in this patient population,” stated Axel Grothey, MD, Mayo Clinic, Rochester, Minnesota.
Each year there are 1,234,000 new CRC cases diagnosed and 608,000 CRC deaths. The vast majority of patients with mCRC require palliative care because there are no good options after progression on all standard treatments. “There is a rationale for multitargeted therapy in this setting. Regorafenib is a multikinase inhibitor, and phase 1 studies suggested that regorafenib has a high disease control rate of about 74%,” he told listeners.
CORRECT randomized patients 2:1 to regorafenib 160 mg/day (3 weeks on and 1 week off) plus best supportive care (BSC) versus placebo and BSC. The study enrolled 760 patients with mCRC who progressed within 3 months of standard therapy (fluoropyridine, oxaliplatin, irinotecan, bevacizumab, cetuximab). Baseline disease characteristics were well balanced between treatment arms. About 55% to 60% had KRAS mutations, around 60% had received at least 4 lines of prior therapy, and every patient had been exposed to prior bevacizumab. “There are no specific therapies for patients with KRAS mutations,” he commented.
Regorafenib improved OS from 5.0 to 6.4 months (P = .0052). “This represents a 23% reduction of death events, which I perceive as clinically meaningful,” Grothey said. The trial was stopped when the primary OS end point was met. The PFS curve showed that the median difference in PFS between the 2 arms, although highly significant, does not explain the difference in survival between the 2 arms, he continued. Median PFS was 1.9 months in the regorafenib arm versus 1.7 months in the placebo group (P <.000001).
“The results suggest that regorafenib exerts its effect on disease control. There was a higher incidence of stable disease with regorafenib (43%) versus 14.9% with BSC alone,” Grothey said. The rate of disease control (response plus stable disease) was 44.8% for regorafenib versus 15.2% for BSC alone (P <.000001). Subgroup analyses are currently being conducted. Preliminary results show that KRAS wild-type and KRAS mutant tumors had similar benefit. Further subgroup analyses will be presented at future meetings. Side effects of any grade with a frequency of ≥10% in the regorafenib arm included hand-foot skin reaction, fatigue, hypertension, diarrhea, rash, anorexia, mucositis, thrombocytopenia, fever, nausea, bleeding, voice changes, and weight loss. Grade 3 side effects with ≥5% frequency were hand-foot skin reaction (16.6%), fatigue (9.2%), hypertension (7.2%), diarrhea (7%), and rash (5.8%).
Toxicities were manageable with dose delays and adjustments. Only 8.2% of the regorafenib group discontinued treatment due to side effects. Grothey was asked to speculate why these results with regorafenib were so much better than those of studies of other multikinase inhibitors in mCRC. He said that “a promiscuous drug” like regorafenib may be needed in this setting and may be best used as a single agent when patients have had prior treatments. Previous studies evaluated use of multitargeted kinase inhibitors in combination with chemotherapy, not as a single agent, he noted.