Long-term outcomes of cladribine tablets in multiple sclerosis: Treatment completion, persistence, and subsequent therapy transitions in Southeast Europe.

This study aimed to assess treatment completion rates, persistence, administration of a third course of cladribine tablets, and switching to other disease-modifying therapies (DMTs) in people with multiple sclerosis (pwMS) treated with cladribine tablets in Southeast European MS centers. We conducted a retrospective, observational, multi-center, and multi-national study including 195 pwMS who initiated cladribine tablets at three centers across three European countries. The mean follow-up period was 4.06 1.17 years. Among the participants, 184 (94.4 %) completed both courses of cladribine tablets, while 7 (3.6 %) were lost to follow-up. Four (2.1 %) switched to another DMT due to disease activity before receiving the second course. Over the follow-up period, 132 (67.7 %) did not require any additional treatment after completing two courses. Eighteen (9.2 %) received a third course of cladribine tablets, while 40 (20.5 %) switched to another DMT, with two of these switches occurring after the third course. The median time to the third course was significantly longer (3.18 years [IQR 2.20-3.91]) compared to the median time to switch (2.27 years [IQR 1.79-3.13]) from the administration of the second course (p = 0.009). An exploratory and hypothesis-generating multivariate logistic regression analysis identified prior DMT use as the only significant predictor for requiring a third course of cladribine tablets and/or switching to another DMT (exp(B) 2.429, 95 % CI 1.034-5.707, p = 0.042). A substantial proportion of pwMS treated with cladribine tablets remain treatment-free for over four years. In selected cases, a third course of cladribine tablets may be beneficial.