Purpose: Progression-free survival (PFS) is not an optimal end point to evaluate therapeutic strategies in advanced colorectal cancer (ACRC). Therefore, composite end points have been proposed to evaluate a chemotherapy strategy when sequential treatments are available: duration of disease control (DDC) and time to failure of strategy (TFS). The goal of this study was to evaluate these alternative end points and their potential surrogacy for overall survival (OS).
Methods: We pooled individual patient data from three randomized trials evaluating chemotherapy strategy, which accrued 1,042 patients with previously untreated ACRC. In these trials, first-line treatment was either oxaliplatin- or irinotecan-based chemotherapy. Compared with TFS, DDC included neither time interval between progression and next sequence of treatment nor time to progression if the best result of the next sequence of treatment was progression.
Results: There was good correlation between DDC and OS (correlation of median: r, 0.62; correlation of hazard ratio [HR]: adjusted copula R(2), 0.72) and between TFS and OS (correlation of median: r, 0.59; correlation of HR: adjusted copula R(2), 0.67). There was no correlation between PFS and OS (correlation of median: r, 0.45; correlation of HR: adjusted copula R(2), 0.47).
Conclusion: DDC and TFS roughly achieved the same results. Both are acceptable new end points to evaluate a therapeutic strategy in ACRC. Although TFS achieved a pragmatic evaluation of a multiline strategy, DDC captured the effect of a specific sequence in a therapeutic strategy.