At week 96 in CLARITY, the annual rate of qualifying relapses among patients older than 45 years was 0.14 for cladribine and 0.28 for placebo. Among patients aged 45 or younger, the annual rate of qualifying relapses was 0.15 for cladribine and 0.37 for placebo. For patients older than 45 years, the annual rate of all relapses was 0.28 for cladribine and 0.55 for placebo. For patients aged 45 years or younger, the annual rate of all relapses was 0.26 for cladribine and 0.65 for placebo. The treatment effect of cladribine, compared with placebo, on qualifying relapses and all relapses was similar for both age groups. In the CLARITY extension, the annualized relapse rate (ARR) was 0.17 in patients aged 45 years or younger and 0.05 in patients older than 45 years.
The mean number of new T1 gadolinium-enhancing lesions and cumulative new T1 gadolinium-enhancing lesions was reduced with cladribine, compared with placebo, in both age groups at week 96 in CLARITY. The mean number of active T2 lesions per patient per scan also was significantly reduced with cladribine, compared with placebo, in both age groups. The reduction was 0.167 in patients older than 45 years and 0.667 in patients aged 45 years and younger. In addition, the mean number of combined unique lesions per patient per scan also was significantly reduced with cladribine, compared with placebo, in both age groups. The reduction was 0.333 in patients older than 45 years and 0.667 in patients aged 45 years or younger.
The proportion of participants who achieved NEDA in CLARITY was 55.6% among patients older than 45 years who received cladribine, 39.6% among patients aged 45 years or younger who received cladribine, 28.2% among patients older than 45 years who received placebo, and 9.5% of patients aged 45 years or younger who received placebo. The odds ratio for achieving NEDA was significantly more favorable for the cladribine group, compared with the placebo group, in both age groups (3.19 for patients older than 45 years and 6.23 for patients aged 45 years or younger). In the CLARITY extension, the proportion of participants who achieved NEDA was 40.9% among patients older than 45 years and 28.2% among patients aged 45 years or younger.
“These data are consistent with previous analyses from CLARITY using a different age cutoff and with results from the overall study population,” said Dr. Giovannoni and colleagues.
Merck KGaA, which manufactures and markets cladribine, supported the study. Dr. Giovannoni and several of his coinvestigators have received speaker honoraria, consulting fees, or other funding from companies including Merck KGaA.