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Source: Aerie Pharmaceuticals

What: Despite reporting that its kicked-off its phase 3 trial of Roclatan, a therapy that treats glaucoma, shares in Aerie Pharmaceuticals (NASDAQ:AERI) tumbled by 12% today.

Take Long View

So what: Roclatan is Aerie Pharmaceuticals next-generation therapy for reducing intraocular pressure in patients with eye disorders, including glaucoma.

Earlier this month, Aerie Pharmaceuticals announced its timeline for an FDA filing for approval of its most advanced candidate, Rhopressa, a drug that matched up to the efficacy of timolol, a long-standing current therapy.

Assuming that safety data that will be coming next year for Rhopressa is solid, Aerie Pharmaceuticals plans to file for FDA approval in the first half of 2016, which could allow it to launch Rhopressa commercially in 2017.

Roclatan is a fixed-dose combination therapy comprising Rhopressa and latanoprost, a prostaglandin analogue therapy that is already being used in this patient population.

In phase 2 trials, Roclatan demonstrated superiority to both Rhopressa and latanoprost, indicating the potential for Roclatan to be the best-in-class therapy option for glaucoma patients.

Now what: Rhopressa has an opportunity to make it to the market more quickly, but Roclatan could end up moving the needle more.

Earlier this year, Rhopressa failed to achieve its primary endpoint in one phase 3 trial, which led to a reconfiguring of the addressable patient population to include only those with intraocular pressure below 26 mmHg for its other phase 3 trial, which succeeded. As a result, Rhopressa -- if approved -- may not be suitable for up to 20% of all glaucoma patients.

Roclatan, however, will be studied in a larger patient pool that includes people with intraocular pressure below 36 mmHg and as a result, if its trials are successful, then it could address most glaucoma patients. Efficacy results from Roclatan's phase 3 trial are expected in about a year, with full safety results likely to come later.

Since it will be a while before we know if Roclatan works, investors should probably focus more on Rhopressa's opportunity than Roclatan. Because glaucoma is a potential billion dollar treatment market, risk tolerant investors might want to keep Aerie Pharmaceuticals on their radar.

Todd Campbell has no position in any stocks mentioned. Todd owns E.B. Capital Markets, LLC. E.B. Capital's clients may have positions in the companies mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.