Allergan's Esmya inches closer to U.S. approval, but FDA label is key to its blockbuster fate

Allergan prospect Esmya is the first oral uterine fibroids therapy to prove safe and effective two U.S. pivotal studies.

Allergan’s uterine fibroids prospect, Esmya, has racked up more data that’ll support the FDA filing it expects to make later this year. But the med will still face some market hurdles that could thwart the major sales potential its maker expects.

Tuesday, the Dublin pharma and partner Gedeon Richter rolled out phase 3 results showing their candidate had topped placebo at staving off uterine bleeding. The data follow up on earlier phase 3 results that dropped last May and make Esmya the first oral uterine fibroids therapy to prove safe and effective two U.S. pivotal studies, Allergan said.

Now, the companies are turning their attention to an FDA filing set to drop in the second half of this year. But the way Barclays analyst Doug Tsao sees it, thanks to “potential labeling limitations” and the “competitive landscape,” the relative market size for Esmya “remains uncertain,” he wrote in a Tuesday note to clients.

Uterine fibroids are the most common benign tumors in women of childbearing age, he noted, amounting to “an incremental 600,000 hysterectomies per year.” AbbVie’s Lupron is also an option for patients, though the “pseudo-menopausal” state it brings on comes along with “burdensome” side effects and symptoms.

Still, the FDA could restrict Esmya’s patient population only to those women eligible for surgery, and it also still unclear whether regulators will restrict dosing of the once-daily treatment to two cycles—both of which could limit the U.S. potential that Allergan pegs between $500 million and $1 billion.

Analysts are less optimistic, Tsao wrote, citing a $286 million peak sales consensus estimate from First Order Analytics. And that’s in part because AbbVie and partner Neurocrine have a competitor on the rise in elagolix, which is currently in phase 3.

Regardless, an FDA green light for Esmya would be a win for Allergan, whose buyer Watson has been here with the med before. The company went after a U.S. approval for Esyma in 2013, but it withdrew a phase 3 study before completion. Allergan replaced the study with the two current phase 3 studies after negotiations with the FDA.

That’s not to say Allergan hasn't already profited stateside off the compound. The company marketed Esmya’s active ingredient as contraception pill Ella in the U.S. before selling those rights to HRA Pharma.