Rozanolixizumab Reaches a Broad Real-World Myasthenia Gravis Population in the USA

A large real-world study has now mapped who actually receives rozanolixizumab, a neonatal fragment crystallizable receptor blocker approved in the USA for adults with anti-acetylcholine receptor or anti-muscle-specific tyrosine kinase antibody-positive generalized myasthenia gravis. The retrospective, observational cohort study drew on de-identified data collected between July 2023 and February 2025 from a patient support program called ONWARD™ and from specialty pharmacy records, and it included 877 adults whose diagnosis of myasthenia gravis was documented before they started treatment. The findings, published in Drugs – Real World Outcomes, offer one of the first detailed portraits of rozanolixizumab use outside the tightly controlled environment of clinical trials.

The cohort looked markedly different from the populations enrolled in the Phase 3 program that secured the drug’s approval. Mean age was 62.2 years, with a standard deviation of 16.6, and 60.3 percent of patients with recorded age were older than 60. In the pivotal MycarinG study, by contrast, the mean age was 51.8 years. More than half of the real-world patients, 54.1 percent, had Medicare coverage, and nearly half, 47.9 percent, lived in the South region of the USA. Women made up 51.5 percent of the cohort. Body weight spanned an unusually wide range, with a median of 87.0 kilograms and recorded values from 36 to 180 kilograms; 30.0 percent of patients with recorded weight weighed at least 100 kilograms, compared with 22 percent in MycarinG. Both older patients and those with obesity are frequently underrepresented in, or excluded from, clinical studies, which makes this broader sample a useful complement to trial data.

Disease characteristics also revealed a heterogeneous population. Among patients with recorded antibody status, 73.1 percent had anti-AChR antibody-positive disease and 15.1 percent had anti-MuSK antibody-positive disease. The anti-MuSK share was higher than the 11 percent seen in MycarinG and higher than the estimated 5 to 8 percent of the overall myasthenia gravis population, a difference the authors attribute partly to rozanolixizumab being the only FcRn blocker available for MuSK antibody-positive disease at the time of the study. Conversely, the anti-AChR proportion was lower than the 90 percent in MycarinG, likely because alternative targeted treatments were available for that subgroup. Most patients, 84.5 percent, were in Myasthenia Gravis Foundation of America Clinical Class II or III, while 13.2 percent had Class IV disease, more than twice the proportion in MycarinG. The mean baseline MG Activities of Daily Living score was 8.4, closely matching the 8.3 reported in the Phase 3 trial.

Treatment history data, collected through a mandatory-free start form, were available for a subset of patients. Among the 546 patients with recorded prior therapies, the most common were corticosteroids at 59.3 percent, intravenous immunoglobulin at 41.9 percent, acetylcholinesterase inhibitors at 36.8 percent, and nonsteroidal immunosuppressive therapy at 22.5 percent. Current therapies, recorded for 780 patients, most often included acetylcholinesterase inhibitors at 49.7 percent, an other category at 49.1 percent, corticosteroids at 39.9 percent, and nonsteroidal immunosuppressive therapy at 20.4 percent. The vast majority of patients, 98.3 percent of the 588 with known treatment history, were naïve to rozanolixizumab when they started, and neurologists were the prescribing specialty for 96.2 percent of the 652 patients with provider information.

Dosing followed the weight-based categories specified in the prescribing information, which assigns 420 mg to patients under 50 kilograms, 560 mg to those between 50 and 99 kilograms, and 840 mg to those at 100 kilograms or more. Among the 344 patients with both weight and dose recorded, most weighed 50 to 99 kilograms and received the 560 mg dose, while 29.7 percent weighed at least 100 kilograms and received 840 mg. The drug became available in the USA in July 2023 after FDA approval in June of that year, and the study captures the first 18 months of commercial use, a period during which clinicians were applying the label’s guidance that subsequent six-week treatment cycles should be based on clinical evaluation rather than a fixed schedule.

Follow-up analysis focused on the 393 of 582 specialty pharmacy patients who had at least one additional treatment date, meaning at least one infusion after the index date. Mean follow-up in this group was 33.5 weeks, with a standard deviation of 19.1, and a median of 31 weeks with a range of 3 to 80 weeks. These patients initiated a mean of 3.0 cycles, and the mean treatment-free interval between cycles was 5.9 weeks. For the subset of 100 patients with at least one year of follow-up since starting rozanolixizumab, the mean number of cycles started in the first year was 3.7, a figure that sits close to the 4.1 cycles observed among patients with more than one year of participation in the Phase 3 clinical trial program.

Kaplan-Meier analysis sharpened the picture of cycle cadence. Among the 100 patients who had either initiated a second cycle or completed a first cycle with at least one year of follow-up, the analysis estimated that 50 percent had started a second cycle by day 58, or 8.3 weeks, after the last infusion of the first cycle. The method accounts for right censoring, which occurs when a patient’s follow-up ends before the event of interest or when the patient discontinues, with the study end date of 3 February 2025 serving as the censoring time. Assuming a six-week treatment pattern, the authors note with the caveat that real-world patterns vary, a mean of roughly four cycles per year implies a treatment-free interval of about six to eight weeks, which aligns with what patients in the clinical trials experienced.

The comparison with a separate real-world analysis using the Komodo Healthcare Map, a claims-based data source, adds nuance. That analysis found patients with at least one year of follow-up initiated a mean of 2.9 cycles in year 1, lower than the 3.7 cycles seen here. The authors suggest the cycle pattern in the current cohort aligns more closely with the Phase 3 program, in which initiation of a new cycle was left to the discretion of the prescribing clinician without a mandatory disease score threshold, an approach they argue is reflected in everyday practice. Because the trial design allowed treatment-free intervals of varying length, the real-world cadence suggests clinicians are personalizing cycles in a manner similar to the trial protocol.

Assessing symptom impact proved difficult. MG-ADL score recording was optional, and follow-up scores were captured for only 29 patients, of whom 27 also had a baseline score. Twenty-eight of these patients had a single follow-up score, and one had five. Scores were recorded within six months of the index date for 5 patients, at 7 to 12 months for 13 patients, and at 13 to 18 months for 11 patients. Overall, 36.4 percent of the scores fell within the first treatment cycle, and the mean reduction from baseline to the lowest follow-up score was 2.6 points. The authors describe a trend toward improvement but explicitly caution that the limited dataset, wide variation in capture timing, and the possibility that patients responding well may need fewer follow-up appointments bias the results, so no firm conclusions about changes in MG-ADL scores have been drawn.

The study’s limitations extend beyond the sparse symptom data. Collection of prior and current therapy information was not mandatory, and while 88.9 percent of patients had current treatment data, only 62.3 percent had prior treatment data, making the latter less reliable. The data are susceptible to bias from individual physician treatment patterns and insurance coverage, and patients who discontinued participation contributed no further data, introducing cohort selection bias during follow-up. The authors note that the length of rozanolixizumab treatment varied from patient to patient and call for future studies to better understand long-term outcomes. Still, as one of the largest real-world studies of rozanolixizumab to date, the work demonstrates that the drug has reached a broad adult population unconstrained by trial exclusion criteria, and that the cycle cadence observed in practice mirrors the individualized approach validated in the clinical trial program, information that could help clinicians manage patient expectations about treatment frequency and gaps between cycles.

Subject of Research: Real-world characterization of US adults with generalized myasthenia gravis initiating rozanolixizumab treatment

Article Title: Characterization of Patients Living with Generalized Myasthenia Gravis Initiating Rozanolixizumab in the USA

Article References: Park, M., Ting, A., Nair, A., Harrold, A., & Kumar, M. (2026). Characterization of Patients Living with Generalized Myasthenia Gravis Initiating Rozanolixizumab in the USA. Drugs – Real World Outcomes. https://doi.org/10.1007/s40801-026-00590-6

Image Credits: AI Generated

DOI: 10.1007/s40801-026-00590-6

Keywords: rozanolixizumab, generalized myasthenia gravis, FcRn blocker, real-world evidence, patient support program, specialty pharmacy, MG-ADL score, treatment cycles, anti-AChR antibodies, anti-MuSK antibodies, cohort study, drug utilization