AstraZeneca bags FDA OK on gout drug lesinurad as safety doubts linger

AstraZeneca's headquarters in London--Courtesy of AstraZeneca

AstraZeneca ($AZN) has scored another drug approval. Just weeks after the FDA flagged through its landmark cancer drug Tagrisso, the agency has delivered an OK on lesinurad, a new gout drug that will be marketed as Zurampic.

The agency's approval marks its 45th marketing green light for the year, easily topping 2014's chart-topping 41 approvals.

Unlike Tagrisso, though, this approval wasn't a clear win for AstraZeneca, raising doubts about whether AstraZeneca can match forecasts of $500 million-plus in annual sales.

The drug fell short of hitting all its primary endpoints in a slate of three late-stage studies, and a slight minority of 6 of the FDA's expert advisers fretted that the drug's safety profile did not merit an approval, leaving AstraZeneca with a narrow one-vote margin in its favor. (The advisory group voted 10 to 4 for an approval.) And those safety concerns were also reflected in the agency's internal review.

Physicians treat gout by going after lower serum uric acid (sUA) levels. In that respect, AstraZeneca ($AZN) believes that it has abundant evidence of success for the drug as an add-on to febuxostat. But in the final study reported out investigators for the company reported that lesinurad, in combination with febuxostat, demonstrated greater sUA lowering to the target for tophaceous gout compared to febuxostat alone "at all months except at the time of the primary endpoint." The 56.6% vs. 46.8% scores did not represent a statistically significant outcome. 

Testing a 200-mg and 400-mg dose, there has been data to support its argument that the drug works as billed. But there's also been mixed results on improving symptoms of the disease and the 400-mg dose is also linked to renal-related adverse events, which is why AstraZeneca stuck with the 200-mg dose for its regulatory applications.

The FDA didn't ignore the safety warnings. The drug will come with a black box warning on potential renal failure and AstraZeneca is being required to run a post marketing study to evaluate renal and cardiovascular safety.

AstraZeneca bagged the drug in its $1.3 billion acquisition of Ardea. And a European approval is likely soon. The European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) recently recommended granting marketing authorization.

Bernstein's Timothy Anderson has projected 2020 sales for this drug at $582 million, though other analysts' projections have reached up to the billion-dollar level as gout afflicts a growing patient population.

"A new approach to treating gout is long overdue given there has been limited therapy innovation over the last 50 years," Lawrence Edwards, the CEO of the Gout and Uric Acid Education Society, said in a statement. "Combination therapy with Zurampic is an important addition to the medicines available to physicians that will help more gout patients reach their serum uric acid treatment targets, which may ultimately relieve their suffering from this painful disease."

- here's the release