To estimate the annualized relapse rate (ARR) in patients with multiple sclerosis (PwMS) who switched from an anti-CD20 to fumarates (anti-CD20-FUM) vs those who switched from an anti-CD20 to cladribine (anti-CD20-CLAD).

Anti-CD20s are highly effective MS disease-modifying therapies (DMTs). However, long-term treatment with anti-CD20s in PwMS can increase infection risks. Strategies to mitigate risks with anti-CD20s include switching to oral DMTs such as FUM (dimethyl fumarate; diroximel fumarate) or oral CLAD.

PwMS were identified retrospectively from 01Jan2017 to 31Dec2023 in the Komodo Health claims database with ≥1 claim for anti-CD20 and ≥1 claim for FUM or CLAD within ≤270 days of their last anti-CD20 claim. PwMS who switched to CLAD but did not have a second dose within 8 weeks of their first dose were excluded. Baseline demographic characteristics, MS severity, relapse rates, baseline anti-CD20, medication use, comorbidities, and MS- and infection-related healthcare encounters/costs were used for 1:1 propensity score matching. MS relapses were identified based on a previously published algorithm.

Prior to matching, there were 134 PwMS in the anti-CD20-FUM cohort and 204 in the anti-CD20-CLAD cohort; 83 PwMS in each cohort after matching. Baseline characteristics were well-balanced (all SMDs ≤0.12). The anti-CD20-FUM and anti-CD20-CLAD cohorts were treated for a mean (SD) of 15.3 (10.8) and 22.7 (12.7) months, respectively, after switching from an anti-CD20. The majority of PwMS in the anti-CD20-FUM (88.0%) and anti-CD20-CLAD (81.9%) cohorts had no relapses after switching. The mean ARR (95% CI) was comparable between the cohorts: anti-CD20-FUM, 0.11 (0.06–0.22) vs anti-CD20-CLAD, 0.10 (0.06–0.16); p=0.76. Additional results will be presented.

These results indicate that relapse rates were comparable between FUM and CLAD and suggest FUM may be as effective as CLAD in controlling disease activity in PwMS transitioning from anti-CD20 therapies.