Eighty patients have received Alemtuzumab. Ten patients transitioned from Alemtuzumab directly to Ocrelizumab due to disease activity. Two (20%) of the 10 patients received three courses of Alemtuzumab, and one (10%) patient received one course prior to transitioning to Ocrelizumab. Eight (80%) of the patients transitioned due to breakthrough disease, while two (20%) transitioned due progression of disability. One (10%) and eight (80%) patients developed grade 2 and grade 3 lymphopenia while on Alemtuzumab, respectively.  Six (60%) and one (10%) patient(s) developed grade 2 and grade 3 lymphopenia while on Ocrelizumab, respectively. One (10%) patient developed a neoplasm after transitioning DMTs.

Three patients (30%) developed disease activity after transitioning to Ocrelizumab. The average annualized relapse rate (ARR) of the patients on Alemtuzumab was 0.353, and after transitioning to Ocrelizumab was 0. Five patients (50%) developed IgG levels greater than 600. No patients had IgG lower than 300. Two patients developed single infections and had IgG levels between 300 and 600. Two additional patients developed recurrent urinary tract infections, both patients had IgG levels greater than 600. 

Patients who demonstrate evidence of disease activity on Alemtuzumab therapy can be safely transitioned to Ocrelizumab therapy with acceptable efficacy and safety profile.