Maintenance immunosuppressive therapy with resumption of immune checkpoint inhibitor treatment to reduce recurrence of immune-mediated colitis.

2642 Background: Immune-mediated colitis (IMC) may limit immune checkpoint inhibitors (ICI) treatment. Current guidelines recommend consideration of resuming ICI when IMC symptoms subside to ≤ grade 1. We aimed to investigate the effect of maintenance immunosuppressive therapy (IST) on the outcome of IMC in patients who resume ICI therapy. Methods: We retrospectively studied patients who resumed ICI therapy after adequate treatment of IMC from March 2015 to June 2020 at MD Anderson Cancer Center. Relevant demographic, oncologic, and ICI data were collected and analyzed. Univariate logistic regression analysis was conducted to assess risk factors of IMC recurrence. Results: We included 102 patients with a median age of 61 years. 66% were males and 97% were Caucasians. 48 patients (47%) received IST maintenance in conjunction with ICI resumption and 54 patients did not. Symptoms of IMC recurred in 28 patients, 8 (17%) in the concurrent IST group and 20 (37%) in the other group. Compared to no concurrent IST group, patients on concurrent IST were more likely to have received combined ICI regimen (60% vs 41%, p = 0.003) and more initial ICI doses (9 vs 5 doses, p = 0.030). Concurrent IST group had significantly longer ICI treatment duration on resumption (72 vs 62 days, p = 0.023), more ICI resumed doses (5 vs 4 doses, p = 0.038), and lower IMC recurrence (17% vs 37%, p = 0.027). Patient who received more IST doses, both therapeutic and prophylactic, had lower rate of IMC recurrence (OR 0.72, p = 0.012; table). IST maintenance treatment (OR 0.34, p = 0.024) was associated with lower IMC recurrence rate after ICI resumption. Vedolizumab was the predominant IST used. Overall survival was comparable among the two groups (p = 0.934). Conclusions: Concurrent IST treatment with ICI resumption after IMC was associated with significantly lower IMC recurrence and more extended ICI treatment while reserving similar overall survival to patients without IST maintenance therapy. Future prospective randomized trial of concurrent IST is still merited for further clarification.[Table: see text]