By the end of 48 weeks of treatment, 27.9% had relapsed on E-PH20 according to the aiNCAT disability score versus 53.6% on those on placebo. By hazard ratio (HR 0.39), the active treatment arm was associated with a highly significant 61% (P = .000039) greater likelihood of avoiding relapse.
When stratified by a background of no therapy, IVIg, subcutaneous immunoglobulins (SCIg), or corticosteroids, all groups in the active treatment arm did better in stage B than any group in the placebo arm, according to Dr. Allen.
In the 48-week deterioration curves, sustained control was observed among responders out to the end of controlled study. Although there appeared to be numerical advantage for those on both E-PH20 and corticosteroids, E-PH20 arms with concomitant IVIg, SCIg, or no treatment also showed sustained control without significant differences between them.
On functional aINCAT scores, 80.9% achieved at least a 1-point improvement. The improvement was at least 2 points in 42.7%, at least 3 points in 28.2%, and at least 4 points in 11.8%.
E-PH20 Is Characterized as Well Tolerated
Injection site erythema (5.4% vs 0%) and injection site bruising (5.4% vs 0.9%) were more common on E-PH20 than placebo, but there was no difference in serious adverse events, and events possibly related to active treatment, such as headache (3.6% vs. 1.8%) were considered to be of mild to moderate severity.
“The safety profile of efgartigimod plus PH20 was consistent with the safety profile of efgartigimod in other autoimmune diseases,” Dr. Allen said.
The weekly subcutaneous injection can be administered within 90 seconds or less, Dr. Allen said. He called this drug a potential “new therapeutic option to reduce treatment burden in patients with CIDP” if it is approved.
There is a need for new options, according to Brett M. Morrison, MD, PhD, associate professor of neurology at the Johns Hopkins School of Medicine, Baltimore, and an expert in neuromuscular disorders. Dr. Morrison was not involved in the study.
“Although there are three currently approved treatments — steroids, IVIg, and plasmapheresis, at least 20% of CIDP patients have minimal or no response” to any of these, Dr. Morrison said. He added that many of those who do respond to standard therapies have a substantial side effect burden that has created a need for alternatives.
Based on the data presented so far, which suggest substantial efficacy and a favorable safety profile, efgartigimod, if and when it becomes available, “would be an important new treatment for CIDP,” according to Dr. Morrison.
Dr. Allen has financial relationships with more than 10 pharmaceutical companies, including Argenx, which provided funding for the ACHIEVE trial. Dr. Morrison reported no potential conflicts of interest.