Introduction: Although use of contraception was pre-specified during cladribine clinical trials for multiple sclerosis, some pregnancies did occur.
Objective: This analysis reports on pregnancy outcomes in the cladribine clinical development program.
Methods: Pregnancy outcomes in female patients (direct pregnancies) and those arising from partner pregnancies (i.e., female partners of male study participants with multiple sclerosis) were evaluated from an integrated safety analysis of ten studies of cladribine in multiple sclerosis (nine clinical trials and a long-term safety registry), with patients treated with cladribine tablets, parenteral cladribine, or placebo (all-exposed cohort; 1976 patients received cladribine and 802 received placebo). Pregnancies that occurred during the 'at-risk' period for cladribine (during treatment or within 6 months thereafter) are reported as a separate group.
Results: In the all-exposed cohort, 70 direct pregnancies occurred among 62 female patients (cladribine, n = 49; placebo, n = 21). Pregnancy outcomes were: live births (cladribine, n = 19 [38.8%]; placebo, n = 9 [42.9%]), elective terminations (cladribine, n = 14 [28.6%]; placebo, n = 4 [19.0%]), spontaneous abortions (cladribine, n = 11 [22.4%]; placebo, n = 5 [23.8%]), and therapeutic terminations (cladribine, n = 5 [10.2%]; placebo, n = 2 [9.5%]); in the remaining placebo recipient, the pregnancy outcome was unknown. There were two reports of congenital malformations (cladribine, n = 1; placebo, n = 1), both of which occurred with pregnancies arising > 2 years after exposure to the last dose of study medication. Sixteen direct pregnancies occurred during the 'at-risk' period for cladribine; outcomes for these were: live births, n = 3 (18.8%); elective terminations, n = 10 (62.5%); spontaneous abortions, n = 2 (12.5%); and therapeutic terminations, n = 1 (6.2%). Corresponding findings for direct pregnancies among placebo recipients were (n = 11): live births, n = 5 (45.5%); elective terminations, n = 2 (18.2%); spontaneous abortions, n = 3 (27.3%); and unknown, n = 1 (9.1%). No cases of congenital malformation were reported for pregnancies during the 'at-risk' period. There were an additional nine partner pregnancies in female partners of cladribine-treated male patients, all of which resulted in live births; of these, two pregnancies occurred within the 'at-risk' period for cladribine.
Conclusions: While limited by the small number of pregnancies and related data from the cladribine clinical development program, highlighting the need for further study, the observations made in the present analysis were generally consistent with epidemiological data on pregnancy outcomes for the general population or women with multiple sclerosis. There were no congenital malformations in pregnancies that occurred during cladribine treatment or within 6 months after the last dose. As the data available for cladribine-exposed pregnancies in patients with multiple sclerosis are limited, a non-interventional post-authorization safety study has been initiated to obtain more information on this subject.