The FDA has approved dupilumab (Dupixent) to treat allergic fungal rhinosinusitis in adults and children ages 6 years and older with a history of sinonasal surgery. 

The approval makes the drug the first approved for the treatment of the condition, according to Regeneron, which makes the medication jointly with Sanofi. Allergic fungal rhinosinusitis is a subtype of chronic rhinosinusitis caused by an extreme reaction to fungi. It can lead to loss of smell, discharge of thick mucus, nasal congestion, nasal polyps, and — in some cases — loss of bone in the sinus cavities.

Dupilumab is an antibody that inhibits interleukin (IL)-4 and IL-13. The medication — which has been approved for atopic dermatitis, bullous pemphigoid, and several other conditions — is administered by injection every 2-4 weeks.

The approval comes after a phase 3, placebo controlled trial of 62 adults and children ages 6 years and older with allergic fungal rhinosinusitis. Patients were randomly assigned to receive age- and weight-based doses of Dupixent (200 mg or 300 mg) every 2 or 4 weeks or a placebo. 

According to Regeneron, the drug was associated with:

• An improvement in sinus inflammation, measured by sinus opacification scores, which fell by 50% in the Dupixent group compared with 10% in the placebo group after 52 weeks.
• Relief of nasal congestion, with patients reporting 67% improvement at week 24 and 81% at week 52, compared with 25% and 11% in the placebo group.
• A reduction in the size of nasal polyps, which shrank by 61% at week 24 and remained reduced at 63% by week 52 in the treatment group, compared with 15% and 4% in the placebo group.
• Improvement in loss of smell, which reduced by 67% at week 24 in patients on Dupixent, compared to 19% in the placebo group.
• A lower treatment burden, with a 92% reduction in the risk for needing steroids or surgery over 52 weeks; only 3% of patients receiving Dupixent required steroids, and 0% underwent surgery, compared with 31% and 7%, respectively, in the placebo group.

Dupixent may cause side effects, including allergic reactions, eye problems, inflammation of blood vessels, psoriasis, and joint aches and pain, according to Regeneron.

Editor's Note: An earlier version of this article misstated the approved indications for dupilumab. This information has been corrected.