Cladribine and alemtuzumab have proven to be effective treatments for relapsing-remitting multiple sclerosis (RRMS), and both act as immune reconstitution therapies administered in a pulsed manner (1–3). Disease activity may occur early after the first course of treatment. However, this does not necessarily imply a treatment failure that requires further modifications to the treatment strategy. For this reason, drug response evaluation is generally performed at least a few months after the second drug course (4). Nevertheless, relevant disease activity early after a treatment course of one of these drugs may sometimes represent a serious clinical problem, potentially leading to permanent disability. In the CLARITY trial, interferon beta-1a rescue therapy was used (1). However, evidence of managing such a problem is scarce, subsequently leading to different clinical choices in a real-world setting (5). Here, we report a case of considerable ongoing disease activity after the first course of cladribine treatment, which was managed with alemtuzumab administration. Data regarding this sequence of therapies, which act through immune system depletion and reconstitution, are lacking, and real-world observations are, therefore, of interest. After alemtuzumab treatment, the patient achieved disease stability; however, several infectious complications were observed. This suggests that this sequential treatment strategy can be applied but warrants caution and careful monitoring.
