The CLARITY (CLAdRIbine Tablets treating multiple sclerosis orallY) study in patients with active MS showed that annualized relapse rates and sustained disability worsening were reduced in patients treated with cladribine tablets annually for two years in short-duration courses, compared with placebo. The efficacy observed in CLARITY was maintained without further active treatment during the CLARITY extension study. In the ORACLE-MS study in patients with a first demyelinating event, cladribine tablets (3.5 mg/kg and 5.25 mg/kg) significantly reduced the risk of conversion to clinically definite MS, compared with placebo. If clinically definite MS occurred in the double-blinded, initial treatment period, patients were treated with subcutaneous interferon beta-1a in an open-label maintenance period.
The present study was designed to assess the annualized relapse rate during the ORACLE-MS open-label maintenance period in patients randomized to cladribine (3.5 mg/kg and 5.25 mg/kg) or placebo in the initial treatment period.
Similar to previous trials, participation in the ORACLE-MS open-label maintenance period was dependent upon the clinical course of the patient’s disease in the initial treatment period. Patients in ORACLE-MS who converted to clinically definite MS (according to Poser criteria) during the initial treatment period entered the open-label maintenance period and were treated with subcutaneous interferon beta-1a (titrated over four weeks up to the dose of 44 μg) administered three times per week.
A total of 109 patients in ORACLE-MS converted to clinically definite MS in the initial treatment period and received at least one dose of interferon beta-1a. The median time on interferon beta-1a was 56.0 weeks. Estimated annualized relapse rates in the open-label maintenance period were 0.14 for patients (n = 25) originally treated with cladribine 3.5 mg/kg, 0.24 for patients (n = 24) originally treated with cladribine 5.25 mg/kg, and 0.42 for patients (n = 60) who originally received placebo in the initial treatment period.
According to the researchers, durable efficacy of cladribine tablets in ORACLE-MS into the open-label maintenance period is consistent with results of the CLARITY and CLARITY extension studies.
This study was sponsored by EMD Serono Inc.
—Glenn S. Williams