Prognostic scores for evaluating the survival benefit of regorafenib or trifluridine/tipiracil in patients with metastatic colorectal cancer: an exploratory analysis of the REGOTAS study

Background Although regorafenib or trifluridine/tipiracil (FTD/TPI) has been recognized as a later-line standard treatment in patients with metastatic colorectal cancer (mCRC), not all patients have beneficial outcomes. This study aimed to develop a prognostic scoring system for evaluating the overall survival (OS) benefit. Methods Patients included in the REGOTAS study, which comprised 489 patients (regorafenib group: 199; FTD/TPI group: 290 patients), were evaluated. OS was analyzed using multivariate Cox proportional model. The prognostic score was calculated using the worst four individual factors weighted by hazard ratio, and the total scores were categorized as low-, moderate-, and high-OS benefit. Results The worst four factors in the regorafenib group were AST > 40 IU/dL (point, + 3), CRP ≥ 1.0 mg/dL (+ 2), number of metastatic organ site ≥ 3 (+ 2), and duration from initiation of 1st-line chemotherapy 37.0 U/mL (+ 2), and ECOG PS ≥ 1 (+ 2) in the FTD/TPI group. These corresponded to a total prognostic score of > 5, 2–4, and 0 points in the regorafenib group and 8, 2–6, and 0 points in the FTD/TPI group. The median OS in the low, moderate, and high OS benefit group was 3.3 (95% CI 3.0–3.7), 8.1 (95% CI 6.4–9.7), and 12.6 months (95% CI 10.6–14.6) in the regorafenib group and 2.8 (95% CI 2.0–3.5), 7.5 (95% CI 6.6–8.3), and 15.4 months (95% CI 9.7–21.2) in the FTD/TPI group. Conclusion These prognostic scores are useful for identifying patients with mCRC who will obtain survival benefits from these drugs.