Disease-modifying treatments for multiple sclerosis have not affected the incidence of neoplasms in clinical trials over 3 decades: a meta-analysis with meta-regression

Objective: Our study aimed to estimate the incidence of neoplasms in clinical trials of DMTs for MS and to test the hypothesis that DMTs increase the risk of neoplasms in the duration of MS randomized controlled trials (RCTs).

Methods: Data were extracted from 42 RCTs of DMTs published between 1991 and 2020. The incidence rate (IR) of neoplasms was estimated by pooling the neoplasms in the active and placebo-treatment arm per patient-year. The neoplasm incidence rate ratio (IRR) of active over placebo-treatment arms was used as measure of the effect of DMTs on the risk of developing neoplasms.

Results: The meta-analysis included 10,638 placebo and 16,360 active-treatment arm patients. A non-significant pooled neoplasm incidence rate ratio (IRR: 1.0797; 95% CI: 0.8281 to 1.4077; P = 0.5711) with no heterogeneity (I² = 0%) was observed in active over placebo-treatment groups from 1991 to 2020. We found a significant association between the incidence of neoplasms and the year of publication in both active and placebo arms of RCTs. Trials of sequestrating and depletive DMTs were associated with significantly higher incidence of neoplasms in both active and placebo-treated arms compared to immunomodulatory treatment trials.

Conclusions: Our study indicates that treatment with DMTs has not modified the risk of neoplasms in MS clinical trials from 1991 to 2020, which may reflect a low carcinogenic potential of DMTs and/or that the neoplasia latencies far exceed the typical MS trial observation periods.