Background

Multiple sclerosis (MS) diagnostic criteria have changed since the ORACLE-MS study was conducted; 223 of 616 patients (36.2%) would have met the diagnosis of MS vs clinically isolated syndrome (CIS) using the newer criteria.

Objective

The objective of this paper is to assess the effect of cladribine tablets in patients with a first clinical demyelinating attack fulfilling newer criteria (McDonald 2010) for MS vs CIS.

Methods

A post hoc analysis for subgroups of patients retrospectively classified as fulfilling or not fulfilling newer criteria at the first clinical demyelinating attack was conducted.

Results

Cladribine tablets 3.5 mg/kg (n = 68) reduced the risk of next attack or three-month confirmed Expanded Disability Status Scale (EDSS) worsening by 74% vs placebo (n = 72); p = 0.0009 in patients meeting newer criteria for MS at baseline. Cladribine tablets 5.25 mg/kg (n = 83) reduced the risk of next attack or three-month confirmed EDSS worsening by 37%, but nominal significance was not reached (p = 0.14). In patients who were still CIS after applying newer criteria, cladribine tablets 3.5 mg/kg (n = 138) reduced the risk of conversion to clinically definite multiple sclerosis (CDMS) by 63% vs placebo (n = 134); p = 0.0003. Cladribine tablets 5.25 mg/kg (n = 121) reduced the risk of conversion by 75% vs placebo (n = 134); p < 0.0001.

Conclusions

Regardless of the criteria used to define CIS or MS, 3.5 mg/kg cladribine tablets are effective in patients with a first clinical demyelinating attack. ClinicalTrials.gov registration: The ORACLE-MS study (NCT00725985).