Japanese Regulatory Agency Weighs in on Upcoming Phase 3 MG Trial for Efgartigimod

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by Alice Melão |

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Argenx efgartigimod trial

Argenx is one step closer to launching a global Phase 3 trial to evaluate the potential of its therapy candidate efgartigimod (ARGX-113) for generalized myasthenia gravis (gMG).

Following feedback from the U.S. Food and Drug Administration in June, the Pharmaceuticals and Medical Devices Agency (PMDA) in Japan has now also provided its guidance on the design of the trial.

Based on the PMDA’s response, argenx expects that data collected in the global Phase 3 registration trial will serve as the basis for filing a marketing authorization for efgartigimod in Japan.

“There remains a significant unmet need in Japan for new treatment options for MG, and we are grateful for the feedback from the PMDA in facilitating a regulatory path towards achieving this goal,” Keith Woods, chief operating officer of argenx, said in a press release.

Planned to start before the end of 2018, the Phase 3 trial is expected to enroll about 150 gMG patients from clinical centers across Japan, North America, and Europe. The trial will include patients who are positive for acetylcholine receptor (AChR) autoantibodies, as well as those whose disease is driven by MuSK and LRP4 autoantibodies.

Participants will be randomized to receive 10 mg/kg of efgartigimod or a placebo for up to 26 weeks. After completion of the predefined treatment duration, the patients will have the opportunity to roll over into an open-label extension study in which they will receive the treatment for another year.

Data from the trial is also expected to support an FDA biologics license application to commercialize the investigative therapy in the U.S.

“We look forward to launching the global Phase 3 trial of efgartigimod in gMG and continuing the ongoing discussions with the PMDA as we map out a potential path to market for our drug candidate, if approved,” Woods said.

Efgartigimod is a man-made antibody fragment specifically designed to promote the destruction and clearance of circulating disease-causing autoantibodies.

Results of a Phase 2 trial (NCT02965573) in 24 myasthenia gravis patients with generalized muscle weakness have already demonstrated efgartigimod’s potential.

Adding efgartigimod to standard treatments reduced disease severity scores in 75% of the patients, compared with only 25% of patients treated with standard-of-care alone. Clinical improvements were seen as soon as after the first of four weekly infusions.

In addition, results from a Phase 1 trial (NCT03457649) in healthy volunteers showed that the investigative therapy can effectively reduce the levels of disease-associated autoantibodies in circulation.

The therapy candidate received orphan drug status in both Europe and the U.S., which is expected to support and expedite its regulatory review and approval.