Batoclimab hits main, secondary goals of Phase 3 trial in China

Treatment eased symptoms of gMG and impact on daily function

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Batoclimab (HBM9161) eased the symptoms of generalized myasthenia gravis (gMG) and their impact on daily function, hitting the main and secondary goals of a Phase 3 clinical trial in China.

No new side effects arose during the trial (NCT05039190) and the experimental therapy, which is being developed by Harbour BioMed, was generally safe and well tolerated.

“We are excited to bring this much-needed therapy to patients, and we look forward to continuing to advance our pipeline of next-generation therapeutics to improve the lives of patients worldwide,” Jingsong Wang, MD, PhD, Harbour’s founder, chairman, and CEO, said in a company press release.

In gMG, the immune system makes self-reactive antibodies that interfere with the normal communication between nerve and muscle cells. This prevents muscles from working properly, leading to fatigue and muscle weakness, hallmark MG symptoms.

Batoclimab is an antibody-based therapy designed to bind and block the action of the neonatal Fc receptor (FcRn) protein, which usually prevents antibodies circulating in the bloodstream from being destroyed. By blocking FcRn, batoclimab should lower the number of antibodies that disrupt nerve-muscle communication, easing the disease’s severity.

“Anti-FcRn treatment has received much attention in patients with gMG, and batoclimab is the first anti-FcRn treatment confirmed efficacious and safe in [the] Chinese gMG population,” said Chongbo Zhao, MD, the trial’s principal investigator.

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Goals include reductions in MG-ADL, QMG scores

The top-line data came from 132 adult patients randomly assigned at the trial’s start (baseline) to undergo two treatment cycles with either batoclimab (680 mg) or a placebo. Each cycle consisted of six weekly under-the-skin (subcutaneous) injections with a three-week interval between them. After the second cycle, which began on week nine, the patients were observed for four more weeks.

The trial’s main goal was to assess the proportion of patients with self-reactive antibodies against the acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) who achieved a reduction of three or more points in the MG Activities of Daily Living (MG-ADL) that was sustained for at least 64 days.

Doctors and researchers use the MG-ADL scale to score symptoms and their impact on daily function based on the patient’s recall of the previous week. The score can range from 0 (normal) to 24 (most severe). A score reduction signals improvement.

Secondary goals included assessing the percentage of patients who achieved a reduction of three or more points in the Quantitative MG (QMG) score that was sustained for at least 64 days. The QMG score rates the severity of symptoms linked to muscle weakness. The total score can range from 0 to 39, with a higher score indicating more severe muscle weakness and more severe disease.

“The pivotal clinical success sets a monumental milestone for the development of new drugs and further reinforces the position of FcRn antagonists in the treatment of MG through high-level evidence-based medicine,” said Zhao, a professor of neurology at Huashan Hospital of Fudan University in Shanghai, China.

The company previously sponsored a Phase 2 clinical trial (NCT04346888) that tested batoclimab (680 mg or 340 mg) against a placebo in 30 adult patients with moderate to severe gMG.

Batoclimab led to a rapid reduction in the levels of disease-causing self-reactive antibodies and this translated into symptoms being alleviated. Most side effects were mild and there were no serious side effects or instances of treatment being stopped due to side effects.

The therapy is being evaluated in a range of autoimmune diseases, including neuromyelitis optica spectrum disorder (NMOSD), according to the company.

“This breakthrough therapy represents a significant advance in the treatment of multiple … [antibody-]mediated autoimmune diseases, where there remains a significant unmet medical need,” Wang said.