By Lisa Seachrist
WASHINGTON — Initial results of two Phase III trials of QLT PhotoTherapeutics Inc.'s Visudyne (verteporfin) therapy shows the light-activated therapy preserves vision in a significant number of patients suffering from the "wet" form of age-related macular degeneration (AMD).
The news pushed QLT's stock (NASDAQ:QLTIF) up more than 23 percent Tuesday, to $28, a gain of $5.312.
Under an agreement with the FDA that granted the therapy priority review status, the 12-month results will serve as the basis for filing a new drug application (NDA) sometime mid-1999. Vancouver-based QLT anticipates European regulatory filings around the same time.
"The good news in this study is that Visudyne was beneficial to a broad patient base," said Julia Levy, president and CEO of QLT. "While we restore sight lost, we are trying to stop the condition in its tracks. Absolutely, we will have to heighten the awareness of eye-care professionals that early diagnosis of AMD makes a difference."
AMD is the leading cause of adult blindness, and the disease affects at least 10 percent of the U.S. population over age 65. Almost 15 percent of all cases of AMD are the wet form, which is characterized by the formation of abnormal leaky blood vessels that grow across the central part of the retina, called the macula. However, nearly 90 percent of the severe vision loss associated with AMD occurs in patients with wet-form AMD as a result of retinal scarring.
QLT's Visudyne therapy is a relatively non-invasive, two-step process that targets rapidly growing abnormal blood vessels. In the first step, patients receive an intravenous infusion of Visudyne, a light-sensitizing agent that binds excess lipoproteins produced by the rapidly growing blood vessels. The drug is then activated by shining a red light into the patient's eyes.
Following discussions with FDA, the company initiated two randomized, double-blind, placebo-controlled clinical trials, involving 609 patients at 22 centers in North America and Europe. Patients received either an infusion of Visudyne or a placebo infusion, followed by a dose of red light. The patients were evaluated every three months, and received additional treatments depending upon the course of the disease.
After 12 months, 61.4 percent of the patients treated with Visudyne therapy had stable or improved vision, compared to 45.9 percent of placebo patients. Overall, treated patients were more likely to retain their vision, compared to the placebo group.
Among treated patients, 16 percent had their vision improve as measured by an increase of one or two lines on a standard vision test, compared to 7 percent of the placebo group.
The trial is ongoing for another 12 months, but at this halfway point, it is showing a statistically significant difference between treated and placebo group in all primary and secondary endpoints.
Neil Bressler, chair of the study advisory group and professor of ophthalmology at the Wilmer Eye Institute of Johns Hopkins University, in Baltimore, said the drug is "unlike other photosensitizers because of the incredibly benign safety profile. Less than 2 percent of the patients dropped out of the study due to adverse events. Basically, there is no risk for this procedure."
Patients with side effects were most likely to have injection-site reactions; mild to moderately decreased vision; and photosensitivity reactions that were self-resolving, since Visudyne is cleared from the body in 24 hours. The only currently available therapy for AMD is laser surgery, which can destroy normal retinal tissue as well as the abnormal tissue.
The company plans to file an NDA for the therapy mid-1999, with an early-2000 target date for launching the product. In the meantime, the two clinical studies will continue, to determine the long-term effects of treatment. QLT is developing the drug in conjunction with Atlanta-based CIBA Vision Corporation, the eye-care unit of Novartis AG.
Luzi von Bidder, president of CIBA's worldwide business unit, said Visudyne "satisfies an unmet medical need. We would like to make the drug available worldwide in the year 2000, and we assume we will be making regulatory submissions in the U.S. and Europe around the same time." *