Clinical outcomes of chemotherapy-based therapies for previously treated advanced colorectal cancer: a systematic literature review and meta-analysis.

Purpose: The purpose of this study was to evaluate clinical outcomes of standard therapies in previously treated, advanced colorectal cancer (CRC) patients.

Methods: A systematic literature review was conducted in Embase, MEDLINE, and CENTRAL databases (January 2000-July 2021), annual oncology conferences (2019-2021), and clinicaltrials.gov to identify studies evaluating the use of licensed interventions in second-line or later settings. The primary outcome of interest was objective response rate (ORR) and secondary outcomes included progression-free survival (PFS) and overall survival (OS). ORR was pooled using the Freeman-Tukey double arcsine transformation. For survival outcomes, published Kaplan-Meier curves for OS and PFS were digitized to re-construct individual patient-level data and pooled following the methodology described by Combescure et al. (2014).

Results: Twenty-three trials evaluating standard chemotherapies with or without targeted therapies across 4,791 advanced CRC patients contributed to our meta-analysis. In the second-line setting, the random effects pooled estimate of ORR was 22.4% (95% confidence interval (CI): 18.0, 27.1), median PFS was 7.0 months (95% CI: 6.4, 7.4), and median OS was 14.9 months (95% CI: 13.6, 16.1). In the third-line or later setting, the random effects pooled estimate of ORR was 1.7% (95% CI: 0.8, 2.7), median PFS was 2.3 months (95% CI: 2.0, 2.8), and median OS was 8.2 months (95% CI: 7.1, 9.1).

Conclusion: Standard treatments have limited efficacy in the second-line or later setting with worsening outcomes in later lines. Given the global burden of CRC, further research into novel and emerging therapeutic options following treatment failure is needed.