Argenx surges after hit in nerve disorder

The Belgian group is riding high as investors look for future successes in other inflammatory diseases.

Argenx has passed its hardest test to date with flying colours. Today’s win for Vyvgart Hytrulo in chronic inflammatory demyelinating polyneuropathy (CIDP) has not only validated the role of FcRn antagonism as a treatment option in the rare nerve disorder but could pave the way for future successes in less demanding inflammatory disease areas.

In the much-anticipated Adhere trial subcutaneous Vyvgart showed a 61% reduction in the risk of relapse versus placebo in patients with CIDP. A filling is now expected by the end of the year. With a win in this key label extension and expectations of positive pivotal data for Vyvgart in pemphigus and immune thrombocytopenia later this year Argenx shares rose 26% today.

With little known about the underlying disease pathology of CIDP it had looked like a huge gamble for Argenx to go after this particular indication. But the group’s clever trial design, which guaranteed patients had active disease, helped Argenx avoid the fate of UCB’s Rystiggo.

All in the design

CIDP is a progressive condition where the nerves' myelin sheaths are destroyed, causing weakness and sometimes paralysis. The current standard of care is intravenous immunoglobulins (IVIG).

In the 322-patient Adhere trial all participants were all initially given Vyvgart after a 12-week washout period. Patients showing a clinical response were advanced into the placebo-controlled part of the trial where time to relapse was measured.

Alongside the 61% reduction in relapse risk, Vyvgart showed a 28% difference in relapse rates against placebo at 24 weeks and a 26% difference at 48 weeks. Although some in the market had been hoping for a higher difference in relapse rate, this is comparable to the relapse reduction seen with IVIG.

To win share from the entrenched immunoglobulin market, where CSL and Grifols dominate, Argenx will almost certainly make much of the fact that a benefit was shown across all measurements of disability used in the trial, in all patient groups, regardless of prior therapy. This will likely see the group apply for as a broad label as possible when it files later this year.

Easy money

Argenx can also make both convenience and tolerability arguments for Vyvgart. The subcutaneous product takes under two minutes to administer, compared with infusion times of five to six hours for IVIG. Side-effects of headache and flu-like symptoms are common with IVIG, while most of Vyvgart’s side-effects were related to injection site reactions.

These factors could be enough to win patients and clinicians over from immunoglobulin therapies and Leerink analysts are forecasting $2bn in sales in CIDP for Vyvgart.

With approval already achieved in the much larger myasthenia gravis indication, and potential label extensions into pemphigus and immune thrombocytopenia, Vyvgart is shaping up to be a sizeable golden goose for Argenx, whose market cap is now over $23bn.

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