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PHOENIX – Across subgroups, patients who had their generalized myasthenia gravis (gMG) treated with rozanolixizumab (Rystiggo) maintained their responses through multiples cycles of treatment, based on extension data from the phase III MycarinG clinical trial.

Those with anti-acetylcholine receptor (AChR)-positive gMG receiving the higher dose of rozanolixizumab saw average Myasthenia Gravis-Activities of Daily Living (MG-ADL) scores fall by 3.7 points after the first cycle of treatment, reaching a 4.0-point reduction after the fourth cycle, reported Robert Pascuzzi, MD, of Indiana University, Indianapolis.

"The benefits of treatment with rozanolixizumab observed in the MycarinG trial were maintained for at least 6 months and as long as 12 months in some of these patients," Pascuzzi told MedPage Today at his poster presentation as part of the Myasthenia Gravis Foundation of America's scientific sessions embedded in this year's American Association of Neuromuscular & Electrodiagnostic Medicine meeting.

Continued improvement with rozanolixizumab did not change with prespecified subgroups by autoantibody status (AChR vs anti-muscle-specific tyrosine kinase [MuSK] antibodies), duration of disease (less than or at least 5.4 years), age (younger or older than 65 years), thymectomy status, or baseline MG-ADL score (less than or at least 5 points).

The main report of showed that rozanolixizumab, at both 7 mg/kg and 10 mg/kg doses, improved patient-reported and investigator-assessed outcomes in patients with gMG.

Based on this study, the FDA approved rozanolixizumab, a neonatal Fc receptor blocker, for adults with gMG in June. It became the first drug approved to treat either of the two most common gMG subtypes, AChR- and MuSK-antibody positive gMG.

Pascuzzi said that the present study supports rozanolixizumab for people with gMG, and noted it is the only drug approved for treatment of patients with MuSK antibody disease.

The finding of similar responses to the drug across subgroups was not surprising, commented Thomas Ragole, MD, of the University of Colorado Anschutz Medical Campus in Aurora.

"The data from the primary clinical trial for rozanolixizumab and similar drugs did not seem to show a whole lot of differences in response rates," he told MedPage Today. "If the disease is an antibody-mediated disease, and the drug reduces these antibodies, you would expect the disease response to be similar across groups, although the magnitude of the effect of the drug could differ among subgroups."

One cycle of rozanolixizumab comprises six weekly subcutaneous infusions. When the effects of treatment wane, another cycle is initiated, Pascuzzi said. "In general, patients require about four cycles of treatment a year," he said, "but it does vary a lot."

Overall, he reported that 152 patients in the study had at least 6 months exposure to rozanolixizumab, and 109 patients had exposure to the drug for at least 12 months. The patients included adults who had been diagnosed with gMG and who were eligible for treatment with immunoglobulin or plasma exchange therapies.

"What we have seen is that patients with generalized myasthenia gravis who are taking rozanolixizumab maintain their improvements out for more than a year," Pascuzzi concluded. As with any drug, he said, "not 100% of people respond, but a majority of them do, and that response is sustained across all the subgroups and with repeated exposure to rozanolixizumab, at least over the time frame of this study."

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