Conference Coverage

Age does not influence cladribine’s efficacy in MS



Treatment with 3.5 mg/kg of cladribine tablets effectively reduces relapse rate and the number of MRI lesions in patients with relapsing-remitting multiple sclerosis (MS), regardless of age. In addition, age does not affect the likelihood that a patient who receives cladribine will achieve no evidence of disease activity (NEDA), according to a study presented at the annual meeting of the Consortium of Multiple Sclerosis Centers.

Dr. Gavin Giovannoni, professor and chair of neurology at the Blizard Institute of Cell and Molecular Science, Barts, and The London School of Medicine and Dentistry, Queen Mary University of London

Dr. Gavin Giovannoni

In the phase 3 CLARITY study, a cumulative dose of 3.5 mg/kg of cladribine over 2 years was associated with significantly reduced relapse rate and disability progression and improved MRI outcomes, compared with placebo. The drug’s efficacy persisted in patients who were switched to placebo in a 96-week extension study.

A post hoc analysis

A 2017 study by Weideman et al. suggested that disease-modifying treatment (DMT) is less effective in older patients. For this reason, Gavin Giovannoni, MBBCh, PhD, professor of neurology at Queen Mary University of London, and colleagues decided to investigate the effect of age on the efficacy of treatment with 3.5 mg/kg of cladribine. The investigators performed a post hoc analysis of the CLARITY and CLARITY extension studies of patients with relapsing-remitting MS. They categorized patients as older than 45 years or age 45 years or younger.

Patients enrolled in CLARITY were between ages 18 years and 65 years. They underwent MRI at pretrial assessment and at weeks 24, 48, and 96 or early termination. The investigators defined a qualifying relapse as one associated with changes in Kurtzke Functional Systems score and other specified clinical parameters. Qualifying relapses were confirmed by an independent evaluating physician who was blinded to treatment assignment.

In the CLARITY extension study, 98 participants who had received cladribine tablets 3.5 mg/kg in CLARITY were randomized to placebo for 2 additional years. Participants who continued on placebo in the CLARITY extension were evaluated according to age at entry into CLARITY.

Dr. Giovannoni and colleagues performed efficacy analyses for qualifying relapses; all relapses; and mean and cumulative numbers of new T1 gadolinium-enhancing lesions, active T2 lesions, and combined unique lesions. They defined NEDA as freedom from qualifying relapses, 6-month confirmed disability progression (as measured by the Expanded Disability Status Scale [EDSS] score), T1 gadolinium-enhancing lesions, and active T2 lesions. The investigators performed equivalent analyses for patients who received placebo in the CLARITY extension.

Age did not influence efficacy

Within each age group, participants in both treatment arms had similar baseline demographic and disease characteristics. In CLARITY, 221 patients were older than 45 years, and 649 were age 45 years or younger. In the CLARITY extension, 22 patients were older than 45 years, and 76 were age 45 years or younger. In CLARITY, but not the extension, the proportion of women was higher in the older group than in the younger group (77.7% vs. 66.1%). In CLARITY, patients aged 45 years or younger had a higher number of T1 gadolinium-enhancing lesions at baseline, compared with older patients.

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