Background Oral cladribine has been effective in clinical trials but only a few studies report real world data. This study assessed efficacy and safety of oral cladribine in an east London hospital.

Methods Data were retrospectively collected on clinical relapses, new MRI lesions, EDSS change, annu- alised relapse rates (ARR), lymphocyte counts, and infections.

Results 56 patients had cladribine in our study (33 had cladribine years 1+2; 23 had only year 1; mean follow-up 24.9 months). Of 56 patients: 3 (5.4%) had a clinical relapse, 7 (12.5%) developed new asymp- tomatic MRI lesions, and 12 (21.4%) had EDSS progression. Overall, ongoing disease activity (either clinical relapse, MRI activity or EDSS progression) was seen in 15/56 patients (26.8%). EDSS improvement was seen in 12 patients (21.4%). Multiple logistic regression showed that prior ARR (p=0.18), baseline EDSS (p=0.52) and gender (p=0.49) did not influence likelihood of ongoing disease activity. Lymphopenia was seen in 31/56 patients (grade 3 = 6; grade 4 = 0).

Conclusions Fewer patients had relapses in our study as compared to other similar studies. This may be due to the lower median baseline EDSS (3.5) and shorter follow-up in our cohort. The proportion of patients with EDSS progression, however, was similar to other studies.