Additional Cladribine tablets treatment courses in multiple sclerosis patients. A retrospective observational study in Latin American countries.

The use of additional cladribine tablets treatment courses is becoming an option in patients with multiple sclerosis (MS) showing disease activity after treatment initiation. Despite the availability over the past year of several expert opinion guidance on the subject, there is a need for real-world assessment of the efficacy and safety of cladribine tablets in these patients. Thus, the aim of the present retrospective observational study is to describe the characteristics of patients that received additional treatment courses within the cohort of cladribine tablets-treated MS patients enrolled in the patient support program (PSP) Adveva® in Latin America countries. Clinical and demographic characteristics of cladribine tablets-treated MS patients enrolled in the PSP Adveva® offered by Merck from launch (2018) until June 30th, 2023 in Latin America countries were included. Within this sample, patients who had received additional treatment courses, defined as treatment courses received after the first 2 treatment courses of 3.5mg/kg in two years, were identified. Further clinical data from these patients was obtained using an anonymized questionnaire completed by their treating physicians. From launch to June 30th, 2023, 1643 MS patients were enrolled in the Latin America PSP Adveva®. In patients with sufficient follow-up, treatment completion (2 courses) was 93 %. Only 2.4 % of patients switched to a different treatment during follow-up. Regarding additional cladribine tablets treatment courses, 14 patients, representing 0.9 % of the total cohort and 1.4 % of treatment completers, received one. The main drivers for receiving additional treatment courses were the presence of clinical and MRI activity (50 %) and the presence of MRI activity without clinical symptoms (42.9 %). In conclusion, this observational real-world study from Latin America PSP Adveva® program confirms the effectiveness of cladribine tablets considering the high completion and low switch out rate. Treatment with an additional course of oral cladribine tablets has been considered in a small proportion of patients with disease activity after treatment initiation.