Harbour BioMed resubmits request for batoclimab approval in China

New BLA to regulatory agency adds long-term safety data on gMG therapy

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Harbour BioMed has submitted a new, revised version of a biologics license application (BLA) to China’s regulatory agency requesting the approval of batoclimab (HBM9161) to treat generalized myasthenia gravis (MG).

The original application was accepted for review last year by China’s National Medical Products Administration (NMPA). The resubmitted application now includes additional long-term safety data on the investigational antibody therapy.

“We are delighted to resubmit the BLA to the NMPA as scheduled and will continuously communicate closely with the NMPA to advance the review process of this innovative therapy,” Jingsong Wang, MD, PhD, founder, chairman, and CEO of Harbour BioMed, said in a company press release.

According to the release, “batoclimab can quickly, significantly, and safely alleviate patients’ symptoms and improve quality of life.”

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Harbour BioMed originally submitted application in 2023

Batoclimab is designed to block the action of neonatal Fc receptor, or FcRn, a protein that helps antibodies stay longer in circulation by preventing them from being broken down. Blocking FcRn is expected to reduce the number of antibodies in the blood, including the harmful ones that cause generalized MG, known as gMG, and its symptoms.

Harbour BioMed’s application drew on data from a Phase 3 clinical trial (NCT05039190) in China that tested how well batoclimab worked against a placebo when given at a dose of 680 mg as six weekly subcutaneous (under-the-skin) injections. A second treatment cycle was given after about a month to most patients based on their response.

A total of 132 adults with generalized MG were involved in the study. The participants had a mean age of 43.8, and about two-thirds (67%) were women. All but one patient tested positive for self-reactive antibodies targeting the acetylcholine receptor (AChR) or the muscle-specific kinase (MuSK), the two most common types of MG-causing antibodies.

The trial met its main goal of sustained improvement, as defined by a reduction of three or more points in the MG Activities of Daily Living (MG-ADL) scale over at least the first four weeks of the first treatment cycle. Lower MG-ADL scores indicate less severe symptoms.

The proportion of antibody-positive patients in the batoclimab group who achieved sustained improvement was nearly double that of patients in the placebo group (58.2% vs. 31.3%), with batoclimab increasing the odds of sustained improvement by 3.45 times.

Based on the results of the Phase [3] clinical trial, which demonstrated the efficacy of batoclimab in both primary and secondary endpoints, we believe this innovative therapy will further enhance the treatment of generalized myasthenia gravis and benefit more patients.

Secondary goals also were met. For example, a greater proportion of antibody-positive patients in the batoclimab group achieved sustained improvement in the Quantitative MG (QMG) scale, defined by a reduction of three or more points in that scale, where lower scores indicate less muscle weakness (64.2% vs. 40.6%).

“Based on the results of the Phase [3] clinical trial, which demonstrated the efficacy of batoclimab in both primary and secondary endpoints, we believe this innovative therapy will further enhance the treatment of generalized myasthenia gravis and benefit more patients,” Wang said.

Treatment-related side effects were more common in patients treated with batoclimab than in those given the placebo (70.1% vs. 36.9%), but most were mild or moderate in severity and none led to treatment discontinuation. The most common side effects reported with batoclimab were swelling, followed by high levels of fatty molecules in the bloodstream, and upper respiratory tract infection.

Patients who completed the trial were offered the option to enroll in an open-label extension study (NCT05332210), in which all were given batoclimab in six-week cycles on top of background treatment. The dose of 680 mg could be reduced to 340 mg as decided based on the investigator’s own judgment.

Enrollment was completed in early 2023, according to a press release reporting on the company’s financial results for that full year. As of November last year, long-term treatment with batoclimab continued to be safe and effective.

Batoclimab also is being tested in another Phase 3 clinical trial, called Flex (NCT05403541), which is recruiting an estimated 240 adults with mild to severe generalized MG in the U.S., Canada, Japan, South Korea, and several European countries.

The Flex trial is sponsored by Immunovant, which is responsible for developing batoclimab in the U.S. and Canada. It will compare the safety and efficacy of batoclimab at a dose of either 680 or 340 mg with a placebo.