Efgartigimod Offers Hope in Chronic Inflammatory Demyelinating Polyneuropathy

Ed Susman,
Ed Susman,
5 Min Read

PHOENIX — A subcutaneous infusion of efgartigimod cut the risk of relapse in patients with a rare but serious immune-mediated neuropathy, according to the phase II ADHERE trial.

Patients with diagnosed chronic inflammatory demyelinating polyneuropathy (CIDP) treated with efgartigimod alfa and hyaluronidase-qvfc (Vyvgart Hytrulo) saw a 61% reduction in the risk of relapse versus placebo, based on time to the first adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) deterioration of ≥1 point (HR 0.39, P=0.000039), reported Richard Lewis, MD, of Cedars-Sinai Medical Center in Los Angeles.

Patients on the study agent also experienced longer time to relapse versus those on placebo, Lewis and colleagues stated in a poster at the American Association of Neuromuscular & Electrodiagnostic Medicine annual meeting. The rapid separation of the Kaplan-Meier curves began at week 4 and was sustained through week 48.

All ADHERE patients were treated in clinics where they received the 90-second infusion of efgartigimod coformulated with recombinant human hyaluronidase PH20 (rHuPH20) which allows for rapid subcutaneous administration of larger volumes, Lewis said. IV efgartigimod (Vyvgart) was approved by the FDA in 2021 as a treatment for generalized myasthenia gravis (gMG) and the subcutaneous formulation was approved in 2023 for gMG.

Lewis told MedPage Today that ADHERE “did not have an at-home component to it…but I think in the future there may very well be a way that patients can self-administer PH20.”

Arindra Jayasekara, MD, of Riverside Community Hospital/University of California Riverside, told MedPage Today said the ADHERE results will broaden the treatment field for people with this rare and serious autoimmune disease of the peripheral nervous system. “Right now, these patients have limited options such as IV immunoglobulin or plasma exchange…I think that eventually the subcutaneous infusion will be something that can be done at home.”

But Jayasekara, who was not involved in the study, cautioned that “patients have to be educated about the risks and benefits. It will be helpful for those individuals who may not have the wherewithal to go to an infusion center. Subcutaneous infusion would be a better choice for these people or others who have problems with IV infusions.”

ADHERE had two stages: Stage A enrolled 322 patients with CIDP who underwent treatment. Responders in stage A were entered into Stage B, where the primary endpoint was the relative risk of relapse based on time to relapse on the INCAT Disability Score, which ranges from 0-10 for arm and leg disabilities.

Patients in both stages were about age 54 and over a third were female. The average time since diagnosis with CIDP was around 4 years. The adjusted INCAT scores for those in stage A, stage B, and placebo were 4.6, 3.1, and 3.3, respectively. Grip strength scores in the dominant hand were 38.5 kPa, 54.9 kPa, and 58 kPa, respectively. More than 60% had unstable, active CIDP.

In stage A, patients on the study agent demonstrated a clinically meaningful mean improvement of 7.7 points on the Inflammatory Rasch-built Overall Disability Scale (I-RODS) of upper and lower limb disability, along with a 12.3 kPa improvement in grip strength. This clinically meaningful benefit was maintained in stage B by patients on the study agent but was lost in those on placebo.

In stage B, those on the study drug had a lower relapse rate versus placebo at week 24 (26% vs 54%) and week 48 (34% vs 60%).

The most frequent treatment-related adverse event (TRAE) was injection site reactions (20% of stage A patients; 10% of stage B patients), but all cases were mild to moderate and resolved over time. Lewis stated that about 5% of patients in both groups reported a serious AE, but none were TRAEs. There were two deaths in stage A (n=1 COVID-19; n=1 worsening CIDP). There was a single pneumonia-related death of a placebo patient in stage B.

Disclosures

The trial was funded by argenx.

Lewis disclosed relationships with CSL Behring, Grifols, Pfizer, Sanofi, argenx, Roche, Johnson & Johnson, Takeda, Boehringer Ingelheim, and Momenta.

Jayasekara disclosed no relationships with industry.

Primary Source

American Association of Neuromuscular & Electrodiagnostic Medicine

Source Reference: Lewis R, et al “Efficacy, safety and tolerability of subcutaneous efgartigimod PH20 in patients with chronic inflammatory demyelinating polyneuropathy: Results from the ADHERE trial” AANEM 2023.

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