51P - Efficacy and safety of sintilimab as first-line therapy in patients with microsatellite instability-high metastatic colorectal cancer: A real-world study

Background

Based on the results of KEYNOTE-177 and Checkmate-142, PD-1 inhibitor was recommended for the first-line treatment of microsatellite instability-high (MSI-H) metastatic colorectal cancer. The present study was conducted to evaluate the efficacy and safety of sintilimab as first-line therapy in patients with MSI-H metastatic colorectal cancer.

Methods

Patients with MSI-H metastatic colorectal cancer who received sintilimab as first-line therapy from January 2019 to June 2021 were retrospectively analyzed based on real-world clinical practice. The primary end point was progression free survival (PFS). Secondary end points included objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety.

Results

632 metastatic colorectal cancer patients were screened and 24 MSI-H metastatic colorectal cancer who received sintilimab as first-line therapy were analyzed. In the general population, the ORR and DCR were 41.7% and 75.0%,and the median PFS was 13.8 months (95% CI=3.4-24.2). The median OS was not reached for the overall group. There were no statistically significant differences in different tumor site and KRAS/NRAS status with respect to ORR, DCR, PFS and OS. Subgroup analysis suggested that there was a statistically significant improvement in OS in favor of without liver metastasis compared with liver metastasis (NR vs. 19.8(0-40.0) months, P=0.030). The incidence of Grade 3-4 adverse events(AEs) was 8.3% and the toxicities were well tolerated and manageable.

Conclusions

Sintilimab as first-line therapy provide a feasible treatment regimen for MSI-high metastatic colorectal cancer with fewer treatment-related AEs. Patients without liver metastasis obtained better OS may be the preferred population for this regimen.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Medical Science and Technique Foundation of Henan Province.

Disclosure

All authors have declared no conflicts of interest.