In the company’s Phase 2 proof-of-concept clinical trial, biopharmaceutical company Harbour BioMed (“Harbour”) sought to understand the impact of batoclimab (HBM9161) on patients with generalized myasthenia gravis (gMG). The study, which took place in China, was extremely important. After all, some patients with gMG often do not respond well to conventional treatments, with a small group completely treatment-averse. However, according to a news release, batoclimab showed promise for patients with gMG.

Batoclimab (HBM9161)

To start, it is first important to understand what batoclimab is. As described by Harbour, batoclimab is:

a novel, fully human monoclonal antibody that selectively binds to and inhibits the neonatal fragment crystallizable receptor (FcRn). In several preclinical studies and Phase 1 clinical trials in healthy volunteers in Greater China and in Canada and Australia, HBM9161 has demonstrated dose-dependent reductions in serum levels of immunoglobulin G (IgG) antibodies and was well-tolerated following subcutaneous and intravenous administration to healthy volunteers.

Altogether, batoclimab was the first subcutaneously administered treatment which showed IgG reductions in both Caucasian and Chinese patients, highlighting its efficacy across backgrounds. Additionally, the therapy received Breakthrough Therapy designation in China.

Within this Phase 2 clinical trial, 30 participants enrolled. Of these, 10 patients received 340mg batoclimab, 11 patients received 680mg, and 9 patients received a placebo. Study findings show:

• The trial achieved its primary efficacy endpoint (improved MG-ADL score). Overall, both 340mg and 680mg batoclimab showed significant improvement in patient quality of life (QOL) and symptom relief as compared to the placebo.
• Patients receiving either dose of batoclimab had significant IgG level reductions of up to 74%.
• As compared to a placebo, batoclimab was quickly efficacious, and promoted sustained and durable response.
• Generally, the treatment was safe and well-tolerated. No serious adverse reactions occurred during the course of the trial. Additionally, no patients discontinued the trial due to side effects.

Moving forward, Harbour now seeks to continue its batoclimab evaluation in a Phase 3 clinical trial.

Generalized Myasthenia Gravis (gMG)

In patients with myasthenia gravis (MG), an autoimmune disorder characterized by muscle weakness, the immune system mistakenly attacks the neuromuscular junction. While no cure exists, there are a variety of treatments designed for patients with MG. However, some patients remain refractory to conventional treatments, meaning these treatments often do not work. This subset of patients have generalized myasthenia gravis (gMG). Typically, patients with gMG do not remain clinically stable on immunotherapy, may relapse, and sometimes develop severe or even life-threatening side effects following treatment. In fact, an estimated 20% of patients with gMG could undergo a myasthenia crisis, which requires respiratory assistance.

gMG symptoms include:

• Disabling fatigue
• Difficulty chewing, swallowing, or speaking
• Shortness of breath and/or difficulty breathing
• Episodes of respiratory failure
• Muscle weakness in both the upper and lower body
• Slurred speech (or other speech-related changes)
• Eyelid drooping
• Changes in vision, such as blurring or double vision
• Thymomas (tumors of the thymus)