Despite a pair of clinical misfires in 2023, argenx has stuck by the thesis that its star drug Vyvgart, also known as efgartigimod, can tackle a wide array of autoimmune diseases linked to immunoglobulin G (IgG) antibodies.
Now, armed with solid phase 3 data, argenx is bolstering its case for Vyvgart’s next potential approval and preparing for a launch later this year—all while the company works to prove the medication’s worth in its inaugural generalized myasthenia gravis (gMG) indication.
Argenx on Tuesday gave a detailed glimpse at positive data from its late-stage ADHERE trial testing Vyvgart Hytrulo—the subcutaneous version of the company’s med—in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).
CIDP is a rare autoimmune disease of the peripheral nervous system that causes fatigue, muscle weakness and loss of feeling in patients’ arms and legs. That weakness can worsen over time or come and go, with the potential for symptoms to significantly impair a person’s ability to function on a day-to-day basis. Without treatment, one-third of people living with CIDP will need a wheelchair, argenx has previously pointed out.
Overall, the majority of CIDP patients who received Vyvgart Hytrulo, regardless of prior treatment, experienced rapid clinical improvement and reduced risk of relapse in ADHERE, argenx explained in a presentation Tuesday at the annual meeting of the American Academy of Neurology (AAN) in Denver.
Thanks to those positive results, Vyvgart Hytrulo appears “on track” for a potential approval in CIDP by the FDA decision date of June 21, argenx CEO Tim Van Hauwermeiren said in an interview.
Vyvgart Hytrulo could represent “the first meaningful innovation in 30-years’ time for these patients,” Van Hauwermeiren said, noting that there are “very few medications in the toolbox today” for doctors and CIDP patients.
For decades, treatment of CIDP has been propped up by steroids and intravenous immunoglobulin (IVIG) therapies, the CEO explained.
Meanwhile, Takeda recently won a U.S. CIDP approval for its subcutaneous immune globulin treatment HyQvia in January, portending a potential showdown later this year should Vyvgart Hytrulo pass muster with the FDA.
Taking a closer look at the data, 67% of CIDP patients in argenx’s ADHERE trial responded to Vyvgart, which also helped slash patients’ chances of relapses by 61%. Argenx’s drug was associated with a fast onset of action, according to the study, which found that 40% of patients had responded to the therapy by the trial’s four-week mark.
Additionally, 81% of patients on Vyvgart Hytrulo saw at least one point of improvement over baseline on their Inflammatory Neuropathy Cause and Treatment disability scores. The scale measures limb impairment in people with CIDP.
To hear Van Hauwermeiren tell it, “a fair number of patients who entered the trial in a wheelchair could leave the study basically out of the wheelchair.”
Aside from efficacy, argenx is touting Vyvgart’s “very clean safety profile,” which stacks up well against IVIG therapies. Those drugs bear black box warnings for thrombosis in certain patients, Van Hauwermeiren explained.
With regards to launch preparations, argenx is “significantly” bolstering its sales force and working to make sure employees who already market Vyvgart for gMG can do the same for CIDP, the CEO said, pointing to a “huge overlap” in neurologists who treat both indications.
To spread the word about CIDP, which the company believes is “underdiagnosed” and “underappreciated,” argenx has also launched an unbranded campaign known as "Shining Through." The campaign includes a website, a 30-second TV spot, a PBS Medical Stories documentary and a three-part “You, Shining Through” reality miniseries. As with myasthenia gravis, argenx co-created the campaign with the help of patient groups and individuals.
Speaking of gMG, argenx has continued to expand Vyvgart’s reach in its flagship indication while bolstering the ongoing clinical and commercial case for the med. In it's initial indication, Vyvgart is "firing from all cylinders," Van Hauwermeiren explained.
Argenx is now marketing Vyvgart for gMG in the U.S., Canada and multiple European countries, as well as China and Japan. The company also has Vyvgart distribution deals in places like the Middle East and Eastern Europe, Van Hauwermeiren said.
As of last year’s third quarter, more than 6,000 patients were on Vyvgart, the CEO added. The most recent numbers on patient use aren’t currently public, he said.
While argenx’s drug is growing in gMG and looks poised to sweep up a CIDP approval this summer, it hasn’t all been smooth sailing for Vyvgart, which notched two trial flops late in 2023.
In November, Vyvgart Hytrulo flunked primary and secondary endpoints in a phase 3 study in the rare bleeding disorder primary immune thrombocytopenia. Less than a month later, Vyvgart missed the mark in a phase 3 study in two subgroups of patients with the chronic blistering disease pemphigus, prompting argenx to abandon its ambitions in the disease area altogether.
Nevertheless, argenx still expects (PDF) to have 15 Vyvgart indications in active development by 2025, the company said during this year’s J.P. Morgan Healthcare Conference in January. Overall, Vyvgart and Vyvgart Hytrulo brought home $1.2 billion in sales in 2023.