Cladribine tablets added to IFN-ß in active relapsing MS: The ONWARD study.

ABSTRACT

OBJECTIVE: To evaluate the safety and efficacy of cladribine tablets in patients still experiencing active relapsing MS despite interferon (IFN)-ß treatment. METHODS: A 96-week phase II study, randomizing patients treated with IFN-ß to cladribine tablets 3.5 mg/kg/IFN-ß or placebo/IFN-ß. Patients were to receive cladribine tablets 3.5 mg/kg/IFN-ß or placebo/IFN-ß in a 21 ratio (n = 172) with safety and exploratory efficacy outcomes being assessed. RESULTS: Adverse events (AEs) and serious AEs were similar across treatment groups, except lymphopenia. Fifty of 124 (40.3%) cladribine/IFN-ß recipients vs 0% of placebo/IFN-ß recipients reported lymphopenia as an AE, with grade 3/4 lymphopenia (laboratory lymphocyte count < 500 cells/mm3) experienced by 79/124 (63.7%) vs 1 (2.1%), respectively. Patients treated with cladribine tablets 3.5 mg/kg/IFN-ß were 63% less likely to have a qualifying relapse than placebo/IFN-ß recipients, and cladribine tablets 3.5 mg/kg/IFN-ß reduced most MRI measures of disease activity. CONCLUSIONS: In patients with active relapsing MS despite IFN-ß treatment, cladribine tablets 3.5 mg/kg/IFN-ß reduced relapses and MRI lesion activity over 96 weeks compared with placebo/IFN-ß but led to an increased incidence of lymphopenia. CLASSIFICATION OF EVIDENCE This study provides Class I evidence that for patients with active relapsing MS despite IFN-ß treatment, cladribine tablets added to IFN-ß reduced relapses and MRI lesion activity over 96 weeks and increased the incidence of lymphopenia. CLINICAL TRIAL REGISTRATION NCT00436826.