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19-03-2024 | Myasthenia Gravis | News

Sustained efficacy with batoclimab in myasthenia gravis

Author: Matthew Williams

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medwireNews: The monoclonal immunoglobulin (Ig)G1 antibody batoclimab offers superior sustained improvement in activities of daily living score versus placebo in people with myasthenia gravis, reports a study from China.

In the randomized phase 3 trial, which was conducted across 27 centers in China between 2021 and 2022, 58.2% of 131 patients with generalized MG who received the neonatal fragment crystallizable receptor (FcRn) antagonist batoclimab achieved at least a 3-point reduction in Myasthenia Gravis Activities of Daily Living (MG-ADL) score from baseline for at least 4 consecutive weeks in the first treatment cycle.

This equated to them being 3.45 times more likely to achieve this primary outcome than the 67 patients who instead received placebo, for whom the rate was 31.3%.

Chongbo Zhao (Huashan Hospital, Fudan University, Shanghai, China) and colleagues comment in JAMA Neurology that the rate of improvement was lower than the 68% rate previously reported for efgartigimod in the ADAPT trial, most likely due to the more stringent definition for sustained MG-ADL improvement of a 3-point reduction versus a 2-point reduction in ADAPT.

The researchers recruited 131 patients (67.2% women) aged a mean 43.8 years who tested positive for acetylcholine receptor (94.7%), muscle-specific kinase antibodies (3.8%), or both (1.5%).

The participants had a MG Foundation of America (MGFA) clinical classification of IIa to IVa, an MG-ADL score of 5 points or more (mean 8.4 points), and a Quantitative MG (QMG) score of 11 or above (mean 18.1 points).

Each treatment cycle comprised six weekly injections of batoclimab 680 mg or placebo, plus standard of care, followed by 4 weeks of observation and a second cycle if needed. In all, 90.0% of patients completed the first cycle and 87.8% of 115 patients completed the second cycle.

Treatment benefit with batoclimab was seen from week 2 in the first cycle, reaching maximum benefit at week 6 (1 week after treatment completion), with mean reductions from baseline at this point of 3.6 points with batoclimab and 1.9 points with placebo.

The main findings were supported by sensitivity analyses, demonstrating the “robustness of study results,” say the researchers.

They also highlight the “broad efficacy” of batoclimab, reporting that a significantly higher proportion of patients in the batoclimab than the placebo arm achieved minimum symptom expression (MG-ADL score of 0 or 1) in the first cycle, at 25.4% versus 4.7%.

And the rate of sustained QMG improvement (≥3-point reduction for at least 4 weeks) in the first cycle was a corresponding 64.2% versus 40.6%, with significantly greater mean reductions at week 6 of 6.4 points versus 1.6 points, respectively.

Treatment with batoclimab showed similar benefits in the second cycle, with sustained MG-ADL improvement seen in 62.7% of patients, compared with 36.4% in the placebo group. Scores diverged at week 1 with a maximal difference at week 5.

When outcomes from the two cycles were combined, sustained MG-ADL improvement was achieved by 50.8% in those who completed both cycles of batoclimab treatment and 23.6% of those who completed both cycles of placebo.

Treatment-related adverse events occurred in 70.1% of patients in the batoclimab arm and 36.9% of those in the placebo arm, mainly peripheral edema (38.8 vs 4.6%), hypercholesterolemia (10.4 vs 1.5%), hyperlipidemia (7.5 vs 1.5%), and upper respiratory tract infections (7.5 vs 7.7%).

Zhao and colleagues conclude that “batoclimab is an important addition to the FcRn antagonist family from a global perspective, especially as a valuable alternative source of FcRn antagonist for China and the surrounding regions,” where mortality rates from MG are high.

They point out that an ongoing open-label extension study to monitor batoclimab’s long-term safety is currently underway.

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2024 Springer Healthcare Ltd, part of the Springer Nature Group

JAMA Neurology 2024; doi:10.1001/jamaneurol.2024.0044

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