Regeneron Pharmaceuticals (NASDAQ:REGN) unveiled phase 3 study data for its autoimmune disease drug Dupixent earlier this week that show it is effective in treating asthma. The success has management planning to file for Dupixent's approval in asthma patients soon, and that suggests Dupixent could win an OK next year. If so, then this drug could end up on the fast track to becoming a billion-dollar drug. 

A big market opportunity

An estimated $50 billion annually is spent directly caring for asthma patients, and a lot of that money goes toward paying for costly hospital care for patients suffering an asthma attack.

A woman with asthma using a rescue inhaler.


Despite the widespread availability of albuterol and levalbuterol inhalers and maintenance therapies, including Advair Diskus and Singulair, asthma control remains difficult for many patients. As a result, there are about 400,000 asthma-related hospitalizations per year in the United States.

Clearly, there's an important need for new treatments that can help patients with asthma and, fortunately, drug developers have stepped up to the challenge by creating new drugs that can better control this condition.

For example, GlaxoSmithKline (NYSE:GSK) -- the maker of Advair Diskus -- won approval for Nucala in November 2015 and Teva Pharmaceutical (NYSE:TEVA) won approval for Cinqair in March 2016. Nucala and Cinqair belong to a new class of drugs that target interleukin-5 to reduce inflammation, and in trials, both drugs reduced attacks in patients with inadequately controlled moderate to severe asthma.

Sales of Nucala and Cinqair so far only represent a tiny fraction of overall spending on asthma, but demand is growing. Nucala's sales totaled 73 million sterling in the second quarter, including 50 million sterling in the United States. For comparison, sales were 20 million sterling in the comparable quarter last year. Teva Pharmaceutical didn't break out Cinqair's sales last quarter. However, it did cite Cinqair as a bright spot in its quarterly performance, suggesting that it's gaining traction, too.

A new contender

Like Nucala and Cinqair, Dupixent is a biologic that reduces inflammation, though unlike those two drugs, it targets interleukin-4 and interleukin-13, two other cytokines involved in immune system response.

In Regeneron Pharmaceuticals' phase 3 study, adding a 300 mg dose of Dupixent to standard asthma therapies reduced severe asthma attacks by 46% after 52 weeks. Patients with 150 or 300 eosinophilic cells/microliter or greater (a sign of IL-4 and IL-13 activity) saw reductions of 60% and 67%, respectively. Dupixent also boosted lung function versus placebo, as assessed by forced expiratory volume over one second.

Importantly, Dupixent's efficacy came alongside a safety profile that doesn't appear to raise too many questions. The overall rate of adverse events and discontinuation for Dupixent was similar to placebo.

A rubber stamp that reads approved.


Looking forward

There's no guarantee that Dupixent will win Food and Drug Administration approval for asthma, but if it does, Regeneron estimates about 1 million U.S. adults and adolescents could benefit from it. Personally, I think it has a good shot at getting a regulatory OK. In my opinion, the bigger question is whether doctors will prescribe it instead of Nucala and Cinqair. For now, that's up for debate.

Perhaps, Dupixent's case with doctors might be helped by the fact that it's already on the market for use in eczema patients. It won FDA approval in that indication earlier this year, and sales of $29 million last quarter show that it's off to a fast start. If Dupixent continues to win over doctors in eczema, it may become easier to convince them to prescribe it for asthma as well. Only time will tell.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.