Claseprubart led to rapid and clinically meaningful improvements in adults with generalized myasthenia gravis (MG), while showing a favorable safety profile, according to results from the Phase 2 MaGic trial presented recently at the MDA Clinical and Scientific Conference.
Patients receiving the investigational therapy experienced better daily function and muscle strength compared with a placebo, with benefits appearing as early as the first week of treatment.
In generalized MG, the immune system attacks communication between nerves and muscles. In many patients this process is driven by antibodies targeting the acetylcholine receptor and activation of the complement system, a part of the immune response. Claseprubart is designed to block a specific protein in this pathway, called active C1s, to reduce damage at the neuromuscular junction.
The MaGic trial enrolled 65 adults with acetylcholine receptor antibody-positive MG and randomly assigned them to receive 300 mg of claseprubart, 600 mg of claseprubart or a placebo every two weeks for 13 weeks. Researchers measured changes in symptoms using several standard scales, including activities of daily living and muscle strength scores.
“With a favorable safety profile, claseprubart demonstrated rapid, statistically significant, and clinically meaningful improvements,” stated the investigators who conducted this research.
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At 13 weeks, patients receiving claseprubart showed greater improvement in daily functioning. MG activities of daily living (MG-ADL) scores improved by 4.6 points in the 300 mg group and 5.4 points in the 600 mg group, compared with 2.8 points for placebo. Muscle strength also improved more with treatment, with reductions in Quantitative Myasthenia Gravis scores of 4.4 and 4.5 points for the two dose groups versus 2.0 points with the placebo.
A higher proportion of patients achieved minimal symptom expression, meaning their symptoms were very mild or nearly absent. This occurred in 37% of patients receiving 300 mg and 27% receiving 600 mg, compared with 14% of those on placebo. Composite scores that reflect overall disease burden also improved substantially more with claseprubart.
The treatment was well tolerated, with no serious adverse events, no serious bacterial infections and no signs of autoimmune complications. Injection site reactions were uncommon and generally mild to moderate. These findings suggest the drug may offer a safer option compared with some existing therapies that broadly suppress the immune system.
For patients, these results point to the possibility of faster symptom relief and improved quality of life with a targeted therapy. A larger Phase 3 study is planned to confirm these findings and determine whether claseprubart could become a new treatment option for people living with generalized MG.
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