Chinese authorities considering approval of efgartigimod for gMG

Under-the-skin formulation now under review by regulators

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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An under-the-skin formulation of efgartigimod is now being considered for approval in China for treating adults with generalized myasthenia gravis (gMG), according to Zai Lab, which will market the therapy if approved.

Chinese authorities have agreed to review a biologics license application (BLA) seeking the approval of this subcutaneous — or given by injection into the fatty tissue just under the skin — formulation of efgartigimod.

This formulation was approved by U.S. regulators last month under the brand name Vyvgart Hytrulo for gMG patients who have antibodies against the acetylcholine receptor, the most common type of MG-causing antibody.

The acceptance by the National Medical Products Administration (NMPA) of Zai Lab’s application in China comes on the heels of a decision last month from the regulatory body to approve the standard intravenous, or into-the-vein formulation of efgartigimod — sold under the brand name Vyvgart — for this patient group.

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Zai Lab has an exclusive license agreement with the therapy’s developer, Argenx, to commercialize Vyvgart in the greater China area. This region includes mainland China, Hong Kong, Macau, and Taiwan.

“We are pleased to have the NMPA’s acceptance of the BLA for efgartigimod alfa injection for subcutaneous use,” Harald Reinhart, MD, president and head of global development in neuroscience autoimmune and infectious diseases at Zai Lab, said in a company press release.

“We’re excited about the potential of efgartigimod to offer patients multiple ways to receive treatment through various administrations and an individualized dosing schedule,” Reinhart said, adding, “We look forward to bringing another first-in-class option for gMG patients in Greater China.”

Efgartigimod, the main ingredient in Vyvgart, works by blocking the neonatal Fc receptor. This protein in the bloodstream helps to stabilize the family of antibodies — called immunoglobulin Gs or IgGs — to which the self-reactive ones that cause gMG.

In doing so, the therapy is expected to speed the breakdown of disease-causing antibodies, thus easing symptoms of muscle weakness for gMG patients.

While Vyvgart is delivered as an into-the-vein infusion directly into the bloodstream over the course of about an hour, Vyvgart Hytrulo is instead designed to be given as a subcutaneous injection that takes only a couple of minutes. Both are given once per week in four-week cycles.

We’re excited about the potential of efgartigimod to offer patients multiple ways to receive treatment through various administrations and an individualized dosing schedule.

As with the request in the U.S., Zai Lab’s application for approval of the subcutaneous therapy in China is backed by data from the Phase 3 ADAPT-SC study (NCT04735432), which involved 110 adults with gMG.

The results generally showed that IgG reductions were comparable between the subcutaneous and intravenous versions of the therapy. Patients treated with Vyvgart Hytrulo experienced a mean 66.4% reduction of IgGs in the bloodstream after 29 days of treatment, while those given the intravenous formulation experienced a mean drop of 62.2%.

Many patients saw reductions in disease severity on Vyvgart Hytrulo, as has been observed with standard Vyvgart.

The safety profile of the two formulations also was similar, with the most common adverse event associated with subcutaneous efgartigimod being mild-to-moderate injection site reactions.

Most trial participants chose to enter an open-label extension study, called ADAPT-SC+ (NCT04818671), in which all participants are now receiving Vyvgart Hytrulo for up to 3.5 years.