The research, published in BMC Psychiatry, was conducted across twelve outpatient psychiatric clinics and followed 155 adults with bipolar disorder who had been taking aripiprazole, quetiapine, or olanzapine for at least eight weeks. All of them had gained weight on those medications, and all were switched to lurasidone because of it. To keep the analysis clean, the investigators excluded anyone who stopped lurasidone or moved entirely to another antipsychotic within the first eight weeks, ensuring that the patients being measured had genuinely stayed on the new drug through the critical early period of treatment change.

The primary endpoint was simple and clinically meaningful: the change in body weight from the moment of switching to sixteen weeks later. Using a non-parametric statistical test appropriate for weight data that do not follow a neat bell curve, the researchers found that mean body weight fell from 74.49 kilograms at baseline to 72.43 kilograms at week sixteen. That difference of 2.06 kilograms came with a 95 percent confidence interval stretching from 2.50 kilograms down to 1.62 kilograms, and the probability that such a change arose by chance was reported as less than one in ten thousand. The median weight change was 2.0 kilograms, with the middle half of patients losing between 0.75 and 3.0 kilograms, indicating that the benefit was not confined to a handful of exceptional responders.

Body mass index told the same story. Average BMI declined from 27.03 to 26.28 kilograms per square meter, again with a p value below 0.0001, a shift large enough to matter at the population level even if it does not yet rescue most individual patients from the overweight range. Perhaps most striking was a descriptive post hoc finding: forty patients, or 25.8 percent of the cohort, achieved a weight reduction of at least five percent, the threshold clinicians typically regard as the minimum for meaningful cardiometabolic benefit. A quarter of patients crossing that line, in a real-world outpatient setting, is a notable result for a simple medication switch.

The benefits were not limited to the bathroom scale. Depressive symptom severity, measured with the 17-item Hamilton Depression Rating Scale, improved by an average of 5.36 points over the sixteen weeks, while global illness severity on the Clinical Global Impression-Severity scale dropped by 0.80 points, both statistically robust changes. This dual effect matters because lurasidone was designed with bipolar depression in mind; it carries established efficacy for the depressive phase of the illness, which is often the most disabling and prolonged component of bipolar disorder. A drug that lightens both mood symptoms and metabolic load addresses two of the biggest drivers of treatment non-adherence at once.

Safety data reinforced the picture. Treatment-emergent adverse events were recorded in only five patients, or 3.2 percent of the cohort, and every one of those events was judged mild. In a field where switching medications often triggers withdrawal effects, symptom flares, or new side-effect burdens, the low rate of recorded problems in this selected group suggests the transition to lurasidone was, for most patients who stayed on it, remarkably well tolerated. The authors stress, however, that the design itself filtered for tolerability: patients who abandoned lurasidone early were excluded, so the study speaks to those who persist with the switch rather than to everyone who attempts one.

That caveat sits at the heart of how these findings should be read. This was a retrospective observational study of a selected follow-up cohort, not a randomized controlled trial. Patients were chosen precisely because they had gained weight on their prior antipsychotic and were motivated or clinically directed to change, and those who stayed on lurasidone for the full observation window may differ systematically from those who did not. Without a control group, some of the weight loss could reflect behavioral changes that accompany a medication switch, increased clinical attention, or regression toward the mean after a period of weight gain. The authors themselves describe the post-switch weight trajectories as descriptive and explicitly call for prospective controlled evaluation.

Even with those limitations, the study fills a genuine gap. Lurasidone’s favorable metabolic profile has been established in registration trials, but real-world evidence in patients switched specifically because of antipsychotic-induced weight gain has been thin, particularly for bipolar disorder as opposed to schizophrenia. The subgroup findings add texture: weight decreases were observed across all three prior medication groups, including the 129 patients who switched from aripiprazole, a drug already considered relatively weight-neutral. That 83.2 percent of the cohort came from aripiprazole makes the consistency of the effect across subgroups especially informative, hinting that lurasidone’s metabolic advantage may be apparent even against a comparatively benign starting point.

The clinical implications reach beyond any single prescription. Antipsychotic-induced weight gain is one of the most persistent obstacles in psychiatry, quietly converting an effective psychiatric treatment into a risk factor for diabetes, hypertension, and cardiovascular disease, the conditions that ultimately shorten the lives of people with severe mental illness by years to decades. Strategies to counter it, from lifestyle programs to adjunctive weight-loss medications, exist but add complexity and cost. A straightforward switch to an efficacious, weight-sparing agent offers an appealingly simple lever, and the Korean data suggest that in ordinary clinic conditions that lever can move both weight and mood in the right direction within four months.

The study was investigator-initiated and partially funded by Bukwang Pharmaceutical, with the funder excluded from design, analysis, interpretation, and the decision to submit, and the authors had unrestricted access to the data. Those disclosures, together with the open-access publication, allow independent scrutiny of a result that will inevitably attract attention from clinicians weighing medication choices for weight-sensitive patients. For now, the message is measured but hopeful: in this carefully characterized Korean cohort, switching to lurasidone for antipsychotic-induced weight gain was followed by modest, statistically convincing weight loss, meaningful improvement in depressive symptoms, and very few adverse events. Whether the same trajectory holds for unselected patients over longer horizons is the question that prospective controlled trials, which the authors themselves now call for, will need to answer.

Subject of Research: Body weight and metabolic outcomes after switching to lurasidone for antipsychotic-induced weight gain in bipolar disorder

Article Title: Body weight changes after switching to lurasidone for antipsychotic-induced weight gain in bipolar disorder: a multicenter retrospective study of a selected follow-up cohort

Article References: Kim, Y.-C., Han, J.-W., Jang, W.-S., Kim, S.-W., Kwak, K.-H., Kwon, S.-J., Kwon, Y.-D., Na, Y.-S., Shin, H.-S., Shin, Y.-S., Song, H.-R., Song, M.-K., & Kim, D.-W. (2026). Body weight changes after switching to lurasidone for antipsychotic-induced weight gain in bipolar disorder: a multicenter retrospective study of a selected follow-up cohort. BMC Psychiatry. https://doi.org/10.1186/s12888-026-08642-5

Image Credits: AI Generated

DOI: 10.1186/s12888-026-08642-5

Keywords: bipolar disorder, lurasidone, antipsychotic-induced weight gain, drug switching, psychopharmacology, body mass index, retrospective study, BMC Psychiatry, weight management, cardiometabolic health, depressive symptoms, Korea

The study, published as a letter to the editors in the Journal of Neurology, comes from the Neurology Unit and Multiple Sclerosis Center at IRCCS Ospedale San Raffaele in Milan, with co-first authors Veronica Marino and Lucia Moiola and co-senior authors Simone Guerrieri and Massimo Filippi. The team conducted a retrospective, real-world comparison of patients with multiple sclerosis who discontinued natalizumab and were subsequently switched either to ocrelizumab, an intravenous anti-CD20 monoclonal antibody, or to ofatumumab, a subcutaneously injected antibody of the same class. The work was approved by the institutional ethics committee at San Raffaele and conducted in accordance with the Helsinki Declaration, with patients providing dedicated informed consent for inclusion in the Italian Multiple Sclerosis and Related Disorders Register.

To understand why this comparison matters, it helps to look at the biology. Both ocrelizumab and ofatumumab belong to a class of drugs that target the CD20 molecule, a protein found on the surface of most B cells, the immune cells that are central players in the inflammatory attacks of relapsing multiple sclerosis. By binding CD20, these antibodies deplete circulating B cells, quieting the autoimmune storm. Yet the two drugs are not identical twins. Ocrelizumab is delivered by intravenous infusion every six months and is approved for both relapsing and primary progressive forms of the disease. Ofatumumab is self-injected under the skin once a month and binds a slightly different region of the CD20 molecule, a difference in epitope that influences how the antibody interacts with its target and with the immune system more broadly.

Those pharmacological distinctions translate into different clinical profiles. Ofatumumab’s subcutaneous route produces rapid and sustained B-cell depletion with a more continuous exposure, while ocrelizumab’s intermittent infusions create a pulsatile pattern of depletion and repopulation. Previous research, including pharmacokinetic and pharmacodynamic analyses of the pivotal OPERA and ORATORIO trials for ocrelizumab and the phase 2 APLIOS study of subcutaneous ofatumumab, has documented these characteristics. A recent comparative analysis published in Annals of Neurology in 2025 suggested that treatment outcomes can differ between patients receiving the two agents, adding urgency to the question of which drug is the better landing spot for patients stepping down from natalizumab.

The natalizumab discontinuation problem is well known to specialists. Natalizumab works by blocking the trafficking of immune cells across the blood-brain barrier, and when it is stopped, that barrier traffic resumes, sometimes with a vengeance. Systematic reviews and meta-analyses have documented post-natalizumab disease reactivation, including severe rebound phenomena in which patients experience bursts of new relapses and magnetic resonance imaging activity within weeks to months of the last infusion. Risk factors for reactivation after cessation have been identified in large cohort studies, and the timing of the switch is critical. A prolonged gap between stopping natalizumab and starting the next therapy leaves a window in which the disease can flare, while certain successor drugs, particularly those with slower onset, may not close that window quickly enough.

Against that backdrop, anti-CD20 agents have emerged as favored switch options, because they act on a different arm of the immune response and can maintain disease control across the transition. Several earlier studies, including pilot work on switching to ocrelizumab from natalizumab given at extended interval dosing in patients at high risk of progressive multifocal leukoencephalopathy, have reported favorable outcomes over follow-up periods as long as 96 weeks. But head-to-head real-world data comparing ocrelizumab and ofatumumab specifically in the post-natalizumab setting had been lacking, leaving clinicians to extrapolate from trials that enrolled different populations. The Milan study was designed to fill that gap using the kind of messy, unselected patient data that randomized trials rarely capture.

The retrospective design has both strengths and limits that readers should keep in mind. On the strength side, real-world cohorts reflect the full spectrum of patients seen in clinic, including those with comorbidities, atypical disease courses, and prior treatment histories that trial populations often exclude. The San Raffaele center is one of the largest multiple sclerosis referral hubs in Italy, and its registry-based approach allows researchers to track outcomes such as relapse rates, magnetic resonance imaging activity, and safety events under routine clinical conditions. On the limit side, retrospective comparisons cannot fully control for why clinicians chose one drug over the other, and such selection bias can color the results. The authors acknowledge the inherent constraints of this design, and the findings should be read as hypothesis-generating evidence that complements, rather than replaces, randomized trials.

Safety is a central concern in any switch strategy. Anti-CD20 therapies deplete B cells broadly, and while they have accumulated a substantial safety record since ocrelizumab’s approval, questions remain about infection risk, hypogammaglobulinemia over the long term, and the theoretical concern that B-cell depletion could modulate the immune response to the JC virus itself. The risk stratification for progressive multifocal leukoencephalopathy relies on anti-JC virus antibody testing using second-generation assays such as the STRATIFY JCV DxSelect, which supports clinical decisions about when natalizumab must be abandoned. The Milan team evaluated safety alongside efficacy in both switch groups, providing clinicians with a side-by-side view of how patients tolerate each transition in everyday practice.

The broader significance of the study lies in the evolution of multiple sclerosis treatment. The field has moved decisively toward high-efficacy therapies earlier in the disease course, and natalizumab, once a flagship of that movement, is increasingly managed with extended interval dosing to reduce infection risk before ultimately being withdrawn in patients who accumulate risk factors. As the population of patients needing a post-natalizumab home grows, the choice between intravenous ocrelizumab and subcutaneous ofatumumab becomes a practical fork in the road, influenced by efficacy signals, safety profiles, dosing convenience, patient preference, and health system logistics. Real-world comparisons like this one give neurologists evidence grounded in clinical reality rather than idealized trial conditions.

For patients and clinicians alike, the message from Milan is one of cautious reassurance paired with continued vigilance. Switching from natalizumab to either anti-CD20 agent appears to be a viable strategy for maintaining disease control, but the details of timing, monitoring, and individual risk profiling remain decisive. The study’s data are held at IRCCS Ospedale San Raffaele and are available upon reasonable request to the corresponding author, an approach that supports transparency and further analysis by the research community. As longer follow-up accumulates and more centers contribute their own switch cohorts, the evidence base will mature, helping to convert one of neurology’s trickiest transitions from an act of clinical judgment into an evidence-based protocol.

Subject of Research: Comparison of ocrelizumab and ofatumumab as post-natalizumab switch therapies in multiple sclerosis

Article Title: Ocrelizumab versus ofatumumab efficacy and safety after natalizumab discontinuation in multiple sclerosis: a retrospective real-world comparison

Article References: Marino, V., Moiola, L., Zanetta, C., Rubin, M., Rossi, L., Margoni, M., Nozzolillo, A., Gattuso, I., Viti, V., Petza, E., Rocca, M. A., Guerrieri, S., & Filippi, M. (2026). Ocrelizumab versus ofatumumab efficacy and safety after natalizumab discontinuation in multiple sclerosis: a retrospective real-world comparison. Journal of Neurology, 273(10), Article 577. https://doi.org/10.1007/s00415-026-14124-1

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14124-1

Keywords: multiple sclerosis, natalizumab, ocrelizumab, ofatumumab, anti-CD20 therapy, B-cell depletion, progressive multifocal leukoencephalopathy, JC virus, drug switching, real-world evidence, disease reactivation, neuroimmunology