Novartis announced compelling new data from two Kesimpta (ofatumumab) studies in relapsing multiple sclerosis (RMS) at the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) 2025 Annual Meeting, demonstrating sustained efficacy and safety over extended treatment periods.
Breakthrough Disease Control After Oral Therapy Switch
The ARTIOS Phase IIIb, open-label, single-arm, prospective study revealed substantial disease control improvements in patients who switched to Kesimpta after experiencing breakthrough disease on fingolimod or fumarate-based therapies. Following the switch, patients achieved a remarkably low annualized relapse rate (ARR) of 0.06 over 96 weeks, with over 90% of participants achieving no evidence of disease activity (NEDA-3).
"These findings add to the growing evidence on the efficacy and safety of ofatumumab after a switch from oral DMTs," stated lead investigator Dr. Riley Bove of the University of California, San Francisco. "Crucially, we observed robust disease control sustained over two years in patients with RMS who did not respond well to oral DMTs."
The study also demonstrated almost complete suppression of MRI activity, with no new safety concerns observed following the switch to Kesimpta, regardless of the previous disease-modifying treatment.
Seven-Year Efficacy in Treatment-Naïve Patients
The separate ALITHIOS open-label extension study provided even more encouraging long-term data for recently diagnosed treatment-naïve patients. More than 90% of patients receiving first-line continuous Kesimpta achieved NEDA-3 at seven years, with sustained low ARR and profound suppression of MRI activity.
"The long-term data from these studies underscore Kesimpta's ability to deliver sustained efficacy and a consistent safety profile for people with RMS," said Norman Putzki, M.D., Ph.D., Global Head Development, Neuroscience & Gene Therapy at Novartis. "These findings reinforce Kesimpta's position as a therapy that empowers patients to take early control of their disease."
Supporting Evidence for Early Intervention
Previous data presented at ECTRIMS 2022 had already highlighted the importance of early treatment initiation. Dr. Jeffrey Cohen, director of research for the Cleveland Clinic's Mellen Center for Multiple Sclerosis, noted that continuous treatment with Kesimpta for up to four years showed sustained safety and efficacy, with approximately 95% of patients maintaining 80% or more compliance with their treatment.
The Phase 3 ALITHIOS open-label extension study subgroup analysis in recently diagnosed treatment-naïve patients demonstrated continued efficacy on relapses, MRI lesions, and risk of disability worsening. When compared to patients who switched to Kesimpta later, the results highlighted the value of earlier initiation of high-efficacy therapy.
Clinical Impact and Treatment Landscape
Multiple sclerosis affects nearly 3 million people worldwide, with relapsing-remitting MS (RRMS) being the most common form, affecting around 85% of patients initially diagnosed with MS. According to the MS Trust, Kesimpta reduces the number of relapses by approximately two-thirds (70%).
Kesimpta is an anti-CD20 monoclonal antibody administered as a once-monthly subcutaneous injection, providing patients with the flexibility of self-administration. The drug has been approved for the treatment of relapsing forms of multiple sclerosis in over 92 countries worldwide, with more than 150,000 patients treated as of August 2025.
The selective mechanism of action and subcutaneous administration of Kesimpta allows precise delivery to the lymph nodes, where B-cell depletion in MS is needed, and preclinical studies have shown that it may preserve B-cells in the spleen.
Safety Profile Maintained
Throughout both studies, Kesimpta maintained a favorable safety profile with no new safety concerns identified. The drug's established safety profile includes potential risks such as infections, hepatitis B virus reactivation, and progressive multifocal leukoencephalopathy, which are monitored through regular clinical assessments.
The new data adds to the previously presented efficacy data from the Phase 3 ASCLEPIOS I/II trials, further supporting Kesimpta's use as first-line therapy at an early stage of the MS disease course. The differences in relapses, MRI lesion activity, and risk of disability worsening observed between continuous treatment and switch groups continue to highlight the value of earlier initiation of high-efficacy therapies like Kesimpta.
