Promising Results for Investigational Myasthenia Gravis Drug

Well Tolerated

On discontinuation of batoclimab, serum total IgG returned to a level comparable with the baseline after 4 weeks. Reversibility of the drug’s effect is important considering the risk for infection from prolonged immune suppression, the authors noted.

The rate of peripheral edema was significantly higher in the treatment than in the placebo groups (39% vs 5%), but all cases were mild or moderate and deemed not clinically significant. The treatment group also had higher rates of upper respiratory tract infections (36% vs 22%) and of urinary tract infections (19% vs 15%).

“Although the incidence of upper respiratory tract and urinary tract infections was higher in the batoclimab group numerically, these were mild infections that did not require special treatment, so this is not a concern,” said Dr. Zhao.

Plasma albumin levels in the batoclimab group decreased significantly throughout the treatment cycle, starting at week 1 and reaching a decline of up to 31% at week 6. These levels increased rapidly toward baseline after treatment discontinuation.

High cholesterol levels were noted in the batoclimab group, plateauing by week 6. But levels returned to near baseline levels within 4 weeks after the final dose, and there were no serious related adverse reactions.

The rate of headache was slightly higher in the treatment group (6% vs 5% for placebo). “This finding may seem minor but could potentially translate into improved adherence in daily practice settings,” the authors wrote.

In previous studies, the efficacy of FcRn inhibitors in the Asian population was only examined in subgroup analyses with limited subjects. Finding an effective FcRn antagonist for China and surrounding regions is particularly important “considering the high mortality rate in hospitalized generalized myasthenia gravis patients in China,” the researchers noted.

The trial included only two treatment cycles, although results of an open-label extension trial examining longer-term efficacy of batoclimab should be available by the end of this year, said Dr. Zhao.

The trial was also not designed to investigate long-term safety, particularly infections and cardiovascular events. Only one study subject was negative for AChR or MuSK antibodies, which prevented researchers from assessing the drug’s efficacy in this subpopulation.
 

Questions Remain

Commenting on the study, Fredrik Piehl, MD, PhD, professor of neurology, Karolinska Institute, Stockholm, Sweden , said that recent studies of the two other FcRn antagonists were short-term and had limited long-term data. “We don’t know how valuable they may be for continued treatment,” Dr. Piehl said.

It’s also unclear how this new treatment modality compares with existing and emerging drug strategies in terms of the long-term benefit-risk balance, he added.

The rate of adverse events with batoclimab was high compared with placebo in this study and higher than in earlier studies of efgartigimod, Dr. Piehl noted.

“In this study, almost twice as many reported adverse events in the active arm compared with controls, while these differences tended to be smaller in previously reported trials,” he said.

The trial was funded by Nona Biosciences (Suzhou). Dr. Zhao reported being a full-time employee of Nona Biosciences (Suzhou), a subsidiary of Harbour BioMed Inc. He also reported receiving advisory board/consultant fees from Nona Biosciences, Roche, Sanofi, and Zailab outside the submitted work. Dr. Piehl has received research grants from Janssen, Merck KGaA, and UCB; and fees for serving on DMC in clinical trials with Chugai, Lundbeck, and Roche; and preparation of expert witness statement for Novartis.

A version of this article first appeared on Medscape.com.