Multicenter Cohort Study to Assess the Association between Changes on Imaging and Outcome after Regorafenib Treatment (KSCC1603)

Background: Molecular targeted drugs having angiogenesis-inhibiting properties allow the induction of necrosis inside tumors. We retrospectively investigated the relationship between changes on imaging associated with regorafenib (REGO) and treatment outcomes using real-world data. Patients and Methods: The eligibility criteria included an ECOG PS of 0-1, a starting dose of 120 or 160 mg/day of REGO, and a duration of treatment of at least 35 days. Regarding changes on imaging, cavitation in lung lesions (CLL), morphologic response of liver lesions (MRL), and change of liver metastasis density (CLD) were evaluated. Results: We finally screened 671 cases, and 226 cases were eligible. In total, 172 and 145 patients had lung and liver metastases, respectively. Among the patients with lung metastasis, CLL was found in 69 patients (40.0%). The median progression-free survival (PFS) of the patients with and those without CLL was 3.2 and 2.4 months, respectively (hazard ratio [HR] = 0.758; 95% confidence interval [CI]: 0.529-1.087), and the median overall survival (OS) of these groups was 10.5 and 8.9 months, respectively (HR = 0.862; 95% CI: 0.579-1.285). MRL and CLD of liver metastasis were analyzed in 145 and 90 patients, respectively. The median OS with and without MRL was 8.9 and 8.2 months, respectively, whereas the median OS with and without CLD was 11.6 and 7.7 months, respectively (HR = 0.523; 95% CI: 0.275-0.992). Conclusion: CLL may predict PFS but not OS among patients with lung metastasis. CLD was predictive of favorable outcomes for REGO in patients with liver metastasis.