Clinicians widely prescribe disease-modifying therapies to alter the course of relapsing neuroinflammatory disorders. Among modern options, ofatumumab in multiple sclerosis provides powerful disease control as a self-administered, subcutaneous anti-CD20 monoclonal antibody. It selectively depletes circulating B cells and demonstrates high clinical efficacy against acute inflammatory relapses. However, real-world neurological outcomes often show noticeable heterogeneity among treated individuals. While pivotal trials validated standardized dosing regimens, questions remain regarding how physiological variables impact long-term prognosis. Specifically, host metabolic factors like body composition may alter drug pharmacokinetics or exacerbate progressive neurodegenerative mechanisms. Recent prospective multicentre data reveal that elevated body mass index correlates with increased risks of confirmed disability accumulation. Although acute inflammatory attacks remain well controlled, patients with high adiposity experience greater functional worsening. Consequently, neuroimmunologists must evaluate how baseline metabolic health influences long-term therapeutic response. Addressing these physiological interactions helps clinicians refine risk stratification and deliver personalized patient management.

Evaluating Ofatumumab in Multiple Sclerosis Across BMI Strata

To evaluate this issue, investigators conducted a prospective multicentre cohort study across four specialized academic medical centres. They analyzed 536 adult patients initiating subcutaneous ofatumumab for relapsing multiple sclerosis. Researchers stratified the entire cohort into quartiles based on baseline body mass index measurements. The highest quartile consisted of individuals presenting with a body mass index equal to or exceeding 29.2 kg/m². Baseline characteristics, including patient age, sex distribution, disease duration, and Expanded Disability Status Scale scores, demonstrated balanced distribution across quartiles. Because baseline neurological impairment was evenly distributed, preexisting disability did not bias prospective comparative outcomes. Furthermore, all participants adhered to the standard monthly dosing protocol of twenty milligrams subcutaneously. Clinical teams tracked relapses, radiological parameters, and confirmed disability progression during regular prospective follow-up assessments. Therefore, this multicentre real-world study provided an ideal clinical model to isolate the specific impact of body composition on disease activity.

Relapse Suppression and Magnetic Resonance Imaging Parity

The multicentre trial demonstrated that subcutaneous ofatumumab maintained robust anti-inflammatory efficacy across all body habitus categories. Clinical relapse rates remained equally low across every body mass index quartile throughout follow-up. Moreover, the proportion of patients suffering acute clinical attacks showed no statistically significant differences between strata. Radiological surveillance confirmed these reassuring clinical observations through standardized magnetic resonance imaging protocols. The development of new or newly enlarging T2 lesions occurred at comparable, minimal rates across all cohorts. Additionally, contrast-enhancing T1 lesions were similarly rare, indicating consistent suppression of active focal blood-brain barrier breakdown. Therefore, elevated body mass index does not impair the core capability of the therapy to abolish acute inflammatory relapses. However, clinicians must remember that acute focal lesions represent only one dimension of multiple sclerosis pathology. Because visible inflammation remained suppressed in all groups, radiological scans alone failed to reflect the divergent functional trajectories observed clinically.

Disability Worsening and Relapse-Independent Progression

In stark contrast to inflammatory metrics, longitudinal functional outcomes diverged markedly according to patient body habitus. Participants within the fourth body mass index quartile exhibited a significantly higher frequency of confirmed disability worsening. Statistical modeling demonstrated a striking adjusted hazard ratio of 3.33 for confirmed worsening in this highest quartile. Crucially, the researchers distinguished between relapse-associated worsening and progression independent of relapse activity. Relapse-associated worsening occurred at similar rates across quartiles, yielding an adjusted hazard ratio of 1.19. Conversely, progression independent of relapse activity was twice as prevalent in the highest quartile, with a hazard ratio of 2.00. This dissociation proves that disability accumulation progressed silently without preceding acute clinical relapses. Interestingly, analyzing absolute body weight alone failed to predict confirmed disability worsening with statistical significance. Patients in the heaviest weight quartile showed an adjusted hazard ratio of 1.91, which did not attain significance. Consequently, adipose tissue distribution, rather than gross total body weight, appears to drive progressive neurological decline.

Pharmacokinetic Variations and Adipose-Driven Neuroinflammation

Pharmacokinetic evaluations provide key insights into why patients with high body mass index experience accelerated progression. Laboratory analyses revealed that serum ofatumumab trough concentrations were significantly lower in patients within the highest body mass index quartile. Because ofatumumab follows fixed-dose administration, elevated adiposity expands the distribution volume and accelerates therapeutic clearance. Lower circulating drug concentrations might reduce antibody penetration into protected compartments, including secondary lymphoid organs and central nervous system parenchyma. In addition, white adipose tissue acts as an active endocrine organ that secretes inflammatory mediators, including leptin and tumor necrosis factor. These systemic cytokines sustain chronic microglial activation and accelerate subclinical axonal loss. Furthermore, metabolic disturbances like insulin resistance impair oligodendrocyte precursor maturation and endogenous remyelination. As a result, reduced monoclonal antibody exposure converges with adiposity-related neuroinflammation to hasten insidious neurodegeneration. Thus, both altered pharmacokinetics and chronic metabolic inflammation compromise long-term neural preservation.

Translating Evidence into Comprehensive Neurological Care

These clinical findings carry immediate implications for routine practice when managing relapsing multiple sclerosis. Neurologists should avoid equating absent magnetic resonance imaging lesions with complete therapeutic success. Instead, clinicians must recognize body mass index as an independent prognostic marker for silent progression. Therefore, tracking body habitus and implementing sensitive ambulatory metrics, such as timed walking tests, should become routine. Furthermore, healthcare teams must provide comprehensive lifestyle interventions alongside pharmacotherapy. Structured aerobic exercise, dietary counseling, and metabolic weight management can lower systemic adipokine levels and protect neurovascular structures. Additionally, ongoing clinical investigations should explore whether individualized dosing strategies or therapeutic drug monitoring could improve outcomes in patients with high adiposity. Until revised protocols emerge, multidisciplinary care models connecting neurologists with primary care physicians and nutritionists provide optimal care. By managing metabolic risk factors alongside targeted immunotherapy, practitioners can mitigate silent disease progression. Ultimately, integrating metabolic health into neuroimmunology care ensures more comprehensive protection against long-term physical disability.

How does a high body mass index influence ofatumumab effectiveness?

A high body mass index does not impair ofatumumab's ability to suppress acute relapses or new magnetic resonance imaging lesions. However, patients with a body mass index of 29.2 kg/m² or greater experience a threefold increased risk of confirmed disability worsening, largely driven by progression independent of relapse activity.

Why is progression independent of relapse activity higher in patients with obesity?

Higher adiposity reduces circulating ofatumumab trough levels and stimulates persistent systemic inflammation through elevated pro-inflammatory adipokines. This metabolic environment promotes chronic microglial activation and oxidative stress, thereby accelerating neuroaxonal degeneration. Consequently, patients suffer gradual functional deterioration even while peripheral immune therapy successfully prevents acute clinical relapses and new focal brain lesions.

Should clinicians adjust the dosage of ofatumumab based on patient weight?

Current prescribing guidelines recommend a standardized fixed dose of twenty milligrams monthly regardless of body weight. While pharmacokinetic data show reduced serum concentrations in heavier patients, clinical trials have not validated weight-adjusted dosing protocols. Neurologists should focus on aggressive metabolic risk factor management, lifestyle counseling, and close functional monitoring during routine clinical follow-up.

Disclaimer: This content is for informational and educational purposes only... Refer to the latest local and national guidelines for clinical practice.

References

1. Winter P et al. Association of body mass index and clinical response in patients receiving ofatumumab for treatment of multiple sclerosis. J Neurol Neurosurg Psychiatry. 2025 Jul 16. doi: 10.1136/jnnp-2024-335673. PMID: 40050009.
2. Hauser SL, Bar-Or A, Cohen JA, et al. Ofatumumab versus Teriflunomide in Multiple Sclerosis. N Engl J Med. 2020;383(6):546-557. doi: 10.1056/NEJMoa1917246.
3. Kappos L, Wolinsky JS, Giovannoni G, et al. Contribution of relapse-independent progression to disability accumulation in multiple sclerosis. JAMA Neurol. 2020;77(9):1132-1140. doi: 10.1001/jamaneurol.2020.1568.