By Lisa Seachrist
Since receiving an approvable letter for its photodynamic therapy Visudyne (verteporfin) on Feb. 11, QLT PhotoTherapeutics Inc. has been awaiting the final OK to sell the drug as a therapy for age-related macular degeneration (AMD).
The Vancouver, British Columbia-based company released two-year results from its Phase III clinical study (called TAP) demonstrating the beneficial effect of Visudyne therapy is sustained and more pronounced. In November, an FDA advisory panel recommended the therapy for classic "wet form" AMD based on the one-year data from the TAP trial. The company also announced positive Phase III results for patients with pathologic myopia treated for one year with Visudyne.
"This is really good news for patients," said Ken Galbraith, executive vice president for QLT. "Not only is the effect sustained but the magnitude of the benefit is greater. You are almost two times as likely to be better off following treatment with Visudyne than if you were treated with placebo. This really eliminates concerns that the effect is modest or temporary."
While recommending the therapy as a treatment for a disease that currently has no adequate therapy, members of the Ophthalmic Drugs Subcommittee of the Dermatologic & Ophthalmic Drugs Advisory Committee raised concerns whether there were any long-term safety or efficacy issues associated with Visudyne.
The company's two-year results largely satisfy such concerns. The study examined 242 patients with classic wet form AMD. At 24 months, 59.1 percent of patients receiving Visudyne therapy lost less than three lines of vision as measured on a standard eye chart compared to 31.3 percent of patients administered placebo. In addition, patients required fewer Visudyne treatments the second year compared to the first year. The company also reported no increase in side effects with extended Visudyne therapy.
"These data really exceeded our expectations," Galbraith said. "Patients required less-frequent treatments in the second year, making this treatment safe and friendly for patients."
AMD is the leading cause of blindness and the disease affects at least 10 percent of the U.S. population over the age of 65. Almost 15 percent of all cases of AMD are the wet form, which is characterized by the growth of abnormal leaky blood vessels growing across the central part of the retina, called the macula. This overgrowth of abnormal blood vessels, also called choroidal neovascularization, scars the retina. Wet form AMD destroys central vision, which is necessary for reading, driving and recognizing faces.
QLT's Visudyne Therapy is a two-step process that targets rapidly growing abnormal blood vessels. The first step is an intravenous infusion of verteporfin, a light sensitizing agent that binds excess lipoproteins produced by abnormal blood vessels. The drug is then activated by shining a red laser light into the patients' eyes.
The second trial the company reported was in younger patients suffering form pathologic myopia - a progressive loss of vision caused by the elongation of the back of the eye resulting in choroidal neovascularization. The disorder generally occurs in people over the age of 30 and afflicts approximately 50,000 people each year.
In the first year of the study, 86.4 percent of the pathologic myopia patients treated with Visudyne lost less than three lines of vision compared to 66.7 percent of placebo patients. Patients received an average of 3.4 treatments during the year.
"With these patients, you are typically talking about people no longer being able to work," Galbraith said. "And there is no effective treatment to stop the progression of vision loss."
QLT is developing Visudyne in collaboration with Atlanta-based CIBA Vision, the eye care unit of Novartis. The two companies are awaiting final marketing approval from the FDA. Galbraith said once they receive the final word, the drug will be shipped within days.
"We have people who are waiting for this therapy," Galbraith said.
QLT's stock (NASDAQ:QLTI) closed Tuesday at $55.00 a share, down $2.50.