The HiHat trial is a Phase 2 study aimed at evaluating the safety and feasibility of sequential treatment with rituximab and cladribine in patients with relapsing-remitting multiple sclerosis (RRMS). The study follows a prospective, open-label, single-arm design, with 60 RRMS patients receiving both treatments in a controlled regimen: two cycles of rituximab (1,000 mg each, biweekly) followed by two cycles of cladribine (30 mg per cycle for three days per cycle) spaced one month apart. Participants are monitored over 24 months through clinical assessments, MRI, and biomarker analyses. The primary objective is to evaluate whether the rate of serious adverse events (SAE) is acceptably low. Secondary objectives include assessing impacts on MRI lesion count, relapse rates, disability progression, quality of life, and safety.