William Blair said Argenx’s Phase III ALKIVIA results for Vyvgart in autoimmune myositis increased its confidence in the drug’s potential path toward approval in dermatomyositis.
Argenx reported that the study achieved a clinically meaningful and statistically significant improvement in its primary endpoint, total improvement score, versus placebo across the overall trial population.
The results sent Argenx shares about 15% higher to record levels, with William Blair arguing that the market reaction reflects both strong efficacy in immune-mediated necrotizing myopathy and greater confidence in Vyvgart’s potential in dermatomyositis.
ALKIVIA Data Supports Broader Vyvgart Opportunity
William Blair highlighted the strength of the ALKIVIA findings, particularly in immune-mediated necrotizing myopathy, or IMNM.
The firm also said the results improve the outlook for dermatomyositis, or DM, even though some regulatory uncertainty remains around whether the U.S. Food and Drug Administration could request an additional study specifically focused on DM patients.
In William Blair’s view, however, any such study would have a high probability of success based on the ALKIVIA data.
That leads the firm to frame the remaining question as one of timing rather than ultimate approvability.
FDA May Still Require Additional Dermatomyositis Trial
One issue that remains unresolved is whether the FDA will accept the existing data package as sufficient for a dermatomyositis indication or require another dedicated trial.
William Blair acknowledged that this remains a risk for investors.
However, the firm argued that the strength of the current data substantially reduces the clinical uncertainty surrounding such a study.
As a result, William Blair said it increasingly views eventual Vyvgart approval in dermatomyositis as likely, even if the regulatory process ultimately takes longer than investors currently expect.
Argenx Shares Hit All-Time Highs
Argenx shares rose approximately 15% following the announcement, reaching all-time highs.
William Blair said the move likely reflects a reassessment of the commercial potential of Vyvgart across autoimmune myositis indications.
A successful expansion into dermatomyositis could add another meaningful growth opportunity for Vyvgart, broadening its use beyond its existing indications and strengthening Argenx’s position in antibody-mediated autoimmune disease.
The firm reiterated its Outperform rating on Argenx following the results.
