Real-World Data Shows Rituximab Outperforms Cladribine for Relapsing-Remitting MS

In the evolving landscape of relapsing-remitting multiple sclerosis (RRMS) treatment, doctors often weigh aggressive therapeutic options based on clinical trial results and real-world performance. A recent Norwegian observational study, employing a rigorous “target trial emulation” framework, provides compelling evidence comparing two such agents: rituximab (Rituxan) and cladribine (Mavenclad). The study, which followed patients for a median of 4.5 years, found that rituximab demonstrated superior efficacy in controlling disease activity and improving disability outcomes.

The study analyzed data from 285 patients with RRMS at two university hospitals, where treatment preference was based on a patient’s residence. This unique setup allowed for a quasi-random allocation, which helped reduce selection bias and emulate a randomized controlled trial within an observational setting. Researchers used a matching score to ensure the patient groups were comparable in terms of age, sex, disease duration, past treatments, and disability scores.

Superior Disease Control with Rituximab

The findings revealed a clear advantage for rituximab across several key metrics:

New MRI Disease Activity: The primary endpoint of the study showed a stark difference in new MRI disease activity over four years. Only 17% of patients on rituximab experienced new MRI activity, compared to 57% of those on cladribine. This represents an absolute risk reduction of approximately 40 percentage points. Patients treated with rituximab also remained free from new MRI activity for an average of 16.8 months longer than the cladribine group.
Relapse and Discontinuation Rates: Rituximab also significantly reduced the risk of relapse (6% vs. 17%) and the risk of treatment discontinuation (7% vs. 21%), further solidifying its superior disease-modifying capabilities.

Disability and Safety Outcomes

Beyond controlling disease progression, rituximab also showed better outcomes in improving patient disability. While the overall change in disability did not differ between the two groups, a higher percentage of patients on rituximab (21%) showed disability improvement compared to the cladribine group (4%). The odds of achieving NEDA-3 (No Evidence of Disease Activity), a gold-standard measure of treatment success, were also much higher for patients on rituximab.

In terms of safety, the study found the number of hospitalizations for adverse effects was comparable between the two groups. However, more rituximab patients were hospitalized for COVID-19, which the authors speculate could be due to either a greater susceptibility to illness or closer monitoring during the pandemic. There were no reported deaths in either group, and the rates of other infections were similar.

In conclusion, this real-world study provides compelling evidence that rituximab is a more effective long-term treatment option than cladribine for RRMS. It excels at reducing radiological disease activity, preventing relapses, and improving disability outcomes, all while maintaining a comparable safety profile. These findings offer crucial, practical guidance for clinicians weighing treatment options and underscore the value of observational research in a real-world setting.