Sirion Therapeutics, Inc., a privately held ophthalmic-focused biopharmaceutical company, announced today that the US Food and Drug Administration (FDA) has approved its New Drug Application for Zirgan(TM) (ganciclovir ophthalmic gel) 0.15% as a treatment for acute herpetic keratitis (dendritic ulcers). The FDA granted orphan drug designation to Zirgan for this indication in April 2007.
Herpetic keratitis, an ocular disease caused by the herpes simplex virus (HSV), is a significant cause of corneal blindness and a leading indication for corneal transplantation in the US, with approximately 50,000 new and recurrent cases each year. After the initial outbreak, HSV becomes a latent infection in the trigeminal ganglion or cornea, with repeated recurrences that frequently lead to corneal scarring and ocular inflammation, increasing the risk of blindness.
The FDA approval was based on the results of clinical trials conducted by Laboratoires Thea of France in Europe, Asia, and Africa that compared the efficacy and tolerability of Zirgan to acyclovir ophthalmic ointment 3% in patients with herpetic keratitis. Both ganciclovir gel and acyclovir ointment are standard-of-care therapies outside of the US, and selectively target the replication of HSV DNA, unlike older antivirals which affect both healthy and infected cells.
In one open-label, randomized, controlled, multicenter clinical trial which enrolled 164 patients with herpetic keratitis, Zirgan was non-inferior to acyclovir in patients with dendritic ulcers. Clinical resolution (defined as percentage of healed ulcers) at Day 7 was achieved in 77% (55/71) for Zirgan versus 72% (48/67) for acyclovir.
In three randomized, single-masked, controlled, multicenter clinical trials which enrolled 213 patients, Zirgan was noninferior to acyclovir in patients with dendritic ulcers. Clinical resolution at Day 7 was achieved in 72% (41/57) for Zirgan versus 69% (34/49) for acyclovir.
"The approval of Zirgan represents a true advance in topical antiviral therapies in the US," commented Barry Butler, CEO of Sirion. "Up to this point, no therapy targeting only viral-infected cells was available for topical ocular use. Zirgan provides doctors with a much needed modern treatment for herpetic keratitis."
The recommended dosing regimen for Zirgan is 1 drop in the affected eye 5 times per day until the ulcer heals, and then 1 drop 3 times per day for 7 days. Trifluridine ophthalmic solution, which is commonly used for topical treatment of herpetic keratitis, is dosed at 1 drop every 2 hours while awake for a maximum of 9 drops daily until the ulcer heals. Zirgan will be supplied in a 5 gram tube and will be available by prescription through retail pharmacies.
"We anticipate Zirgan will be commercially available to US physicians in early 2010," noted Susan Benton, Senior Vice-President of Sales and Marketing for Sirion. "We're pleased to introduce this important treatment option for herpetic keratitis to the US," she continued, "especially since it has been the standard of care in the Europe for over 10 years. We believe it will provide patients and physicians with an effective, safe, and convenient treatment for herpetic keratitis."