The CORRECT trial demonstrated survival benefits with regorafenib monotherapy in patients with treatment-refractory, metastatic colorectal cancer (mCRC). However, the trial's stringent eligibility criteria for regorafenib may limit its external validity. We aimed to examine treatment attrition rates and eligibility for regorafenib in routine practice. We identified patients at the British Columbia Cancer Agency diagnosed with mCRC who demonstrated disease progression or intolerable toxicity on 2 or more lines of systemic therapy. During the study timeframe, panitumumab and cetuximab were only used in the chemo-refractory setting. Data on clinicopathologic variables and patient outcomes were ascertained and analyzed. Eligibility was determined using the CORRECT trial criteria. A total of 391 patients were identified, among whom only 39% were eligible for regorafenib: 35% in the panitumumab group and 51% in the cetuximab group. The main reasons for ineligibility in all patients were Eastern Cooperative Oncology Group Performance Status (ECOG PS) > 1 (69%), an elevated total bilirubin (21%), and thromboembolic events in the past 6 months (10%). No difference in eligibility for regorafenib was observed between patients previously receiving panitumumab or cetuximab (P = 0.914; 95% CI 0.550-1.951). Kaplan-Meier analyses showed that regorafenib-eligible compared to regorafenib-ineligible patients had an increased median overall survival of 5.3 versus 2.1 months, respectively (P < 0.001). However, Cox proportional hazard analyses showed that only ECOG PS rather than trial eligibility was correlated with outcomes. The strict eligibility criteria disqualify most patients with treatment-refractory mCRC for regorafenib therapy. Future trials should broaden the eligibility criteria to improve external validity.
Keywords: Colorectal cancer; Eligibility; Metastasis; Palliative chemotherapy; Survival.