Impact on survival of severe immuno-related adverse events in deficient mismatch repair/microsatellite instable-high digestive cancers treated with immunotherapy.

BACKGROUND

Deficient DNA mismatch repair/microsatellite instability-high (dMMR/MSI-H) cancers are very sensitive to immune checkpoint inhibitors (ICIs), yet their use is frequently complicated by immune-related adverse events (irAEs). Our study analyzed the impact of grade ≥3 irAEs (immune-related severe adverse events (irSAEs)) on survival in patients with dMMR/MSI-H digestive cancers treated with ICIs.

METHODS

We conducted an international, multicenter, ambispective study involving 1,175 patients from 34 centers. The primary endpoint was the correlation between the occurrence of irSAEs and progression-free survival (PFS). Secondary endpoints included factors associated with irSAEs, correlation between irSAEs and overall response rate (ORR) and overall survival (OS). Prespecified landmark and time-dependent survival models were used to account for the time to irSAE occurrence.

RESULTS

Among 1,175 patients treated with ICIs for digestive cancers, 49.1% were female, median age was 66.9 years (IQR 53.7-77.3) and 82.9% had colorectal cancer. Overall, 382 patients (32.5%) had an irAE, including 117 (10.0%) irSAEs. Median time to irSAEs occurrence was 3.78 months (IQR 1.97-7.62). The most frequent irSAEs were gastrointestinal (3.4%), hepatic (1.8%) and dermatologic (1.0%). The only factor associated with irSAEs was the use of an ICI combination versus monotherapy (20.0% vs 11.4%, p=0.03). Among patients with irSAEs, 71.5% received oral and 29.8% intravenous corticosteroids, and 15.7% immunosuppressive agents. Overall, in 26.9% of patients, ICIs were resumed following irSAEs, with an irAE recurrence rate of 57.1%. irSAE was associated with a better ORR (48.6% vs 34.6%, p<0.0001). The multivariable Cox model revealed that irSAE as a time-dependent variable was not associated with better PFS (HR=1.280 (95% CI 0.898 to 1.824), p=0.172) or OS (HR=1.043 (95% CI 0.712 to 1.528), p=0.828). Likewise, landmark analysis at 3 months and 6 months also showed that irSAEs were not associated with better PFS or OS.

CONCLUSIONS

The occurrence of irSAE was not independently associated with better survival in patients with dMMR/MSI-H digestive cancers treated with ICIs.