Trials leading to Cladribine (CLD) approval for the treatment of Multiple Sclerosis (MS) were conducted over a decade ago: there is a need of proof of CLD efficacy and safety profile in the present MS therapeutic landscape.
To evaluate CLD efficacy and safety profile in the current MS population, and to identify early predictors of response.
Before the drug was marketed under the national healthcare system, in Italy CLD was available through a Free Of Charge (FOC) program. We asked all participating MS centres to contribute to the present study, collecting demographic, clinical and MRI data of the patients who received CLD in the FOC program.
56 MS centres participated to the study, for a total of 236 patients (71% F) (mean age: 39 + 11,5 years; mean disease duration: 10 + 8,5 years). Mean Annualized Relapse Rate (ARR) in the two years before CLD was 0,7 + 0,6; median baseline EDSS was 3 (quartiles 1,5-3,5; range 0-6,5). 53 patients (22,5%) were treatment naïve, 107 (45,3%) switched to CLD from first-line DMDs (for inefficacy), 76 (32,2%) switched to CLD from a second line therapy (33/76 for safety or loss of tolerability, 43/76 for inefficacy). Mean follow up was 12,2 + 5 months. 84,7% of the patients were relapse-free at follow-up. Mean ARR at follow-up was 0,2 + 0,6. Patients taking CLD as first therapy were less likely to experience a relapse (HR 0,6; 95% CI: 0,2-0,8; p = 0,04) while a higher baseline ARR was a predictor of clinical activity (HR 2,7, 95% CI: 1,4-5,6; p = 0,004). Median EDSS at follow up was 2 (quartiles 1-3,5). EDSS was stable in 73.7%, improved of at least 1 point in 21,6% and worsened of at least 1 point in 4,7% of the patients. 157/236 patients completed one year of follow up. Of these 92 (59,7%) reached No Evidence of Disease Activity (NEDA-3); NEDA-3 was achieved more frequently by naive patients (70%) than switchers from a first (57%) or a second line (50%) (HR 2,3; 95% CI: 1,01-5,3; p = 0,04). 33/236 patients reported at least one adverse event (AE), most frequently infections (15 cases); other AEs included gastrointestinal side effects, cutaneous rash, aphthous stomatitis and headache. Two severe AEs were reported (one pneumonia, one melanoma).
Even with the limitations of a retrospective study, our data confirm CLD safety and efficacy profile. Consistently with previous studies on patients with a first demyelinating event, CLD efficacy is maximized when used early in the course of MS.