Abstract
Cladribine is an immune reconstitution therapy for multiple sclerosis (MS) that selectively produces long-term reductions in highly pathological memory B cells, with temporary reductions in other B- and T-cell subsets, thereby restoring immune function close to baseline levels in the short term. Here, we describe two cases of relapsing MS (RMS) treated with a second course of cladribine. Both patients were initially diagnosed with clinically isolated syndrome and later enrolled in the ORACLE-MS and CLASSIC-MS studies. After receiving cladribine in ORACLE-MS, neither patient required additional treatment until RMS was diagnosed 8-10 years later. In each case, a second course of cladribine was administered, and both patients remained without clinical or radiological disease activity as per their most recent assessments (November 2023 and August 2023, respectively). No serious or unexpected adverse events were reported during follow-up. These cases provide further real-world evidence of the long-term effectiveness and safety of cladribine after a second course of treatment in patients with RMS.