By Kim Coghill
QLT Inc. said it received an approvable letter from the FDA and expects within the next two to four months to receive agency approval for Visudyne therapy for treatment of predominantly classic subfoveal choroidal neovascularization (CNV) caused by pathologic myopia and ocular histoplasmosis syndrome.
QLT and its collaboration partner, Atlanta-based Novartis Ophthalmics, the eye health unit of Novartis AG, submitted a supplemental new drug application for the product, which in April was approved to treat wet age-related macular degeneration (AMD) in CNV patients. (See BioWorld Today, April 14, 2000.)
"We've submitted all of our supplemental information and it is just a matter of them reviewing it and asking questions if necessary," said Julia Levy, president and CEO of Vancouver, British Columbia-based QLT.
Choroidal neovascularization is a growth of abnormal blood vessels under the central part of the retina or macula.
CNV due to pathologic myopia is caused by abnormal blood vessels that grow under the center of the retina as a result of an abnormal elongation of the back of the eye associated with severe near-sightedness or myopia. It usually occurs among people 30 and over and can result in a progressive loss of vision. Worldwide, there are about 50,000 new cases of CNV due to pathologic myopia.
Ocular histoplasmosis syndrome is caused by a fungal infection of the retina. It can lead to severe, irreversible vision loss and is a leading cause of blindness in adults who have lived in the geographic areas where the soil mold Histoplasma capsulatum is found. The condition is caused by inhaling the fungus from soil or other areas that have been contaminated by the droppings of birds or bats.
Robert Uhl, a research analyst with Leerink Swann & Co. in Boston, said sales for both indications should be between $30 million and $40 million a year. "One of the problems is that no one really knows how many patients there are out there [who suffer from these indications].
"But Visudyne is the best product out there for these indications," Uhl said. "It doesn't cure degeneration of the retina, but it delays it."
QLT's stock dropped 31 percent to close at $28.062 in December after the company announced slower-than-expected growth for Visudyne in AMD. Company officials at that time said the drug was still bound for blockbuster status with projected sales of $500 million to $600 million in a peak year, and the product was expected to log $36 million to $38 million in the fourth quarter 2000. (See BioWorld Today, Dec. 15, 2000.)
Uhl said the drop in December resulted from Visudyne failing to produce the expected minimum of $40 million in fourth-quarter sales.
QLT's stock (NASDAQ:QLTI) closed Monday at $27.687, up $1.937, or 7.5 percent. Novartis AG's stock (NYSE:NVS) closed at $42.89, up 49 cents.
Visudyne is a two-step procedure that can be performed in a doctor's office. First, Visudyne is injected intravenously into the patient's arm. A nonthermal laser light is then shone into the patient's eye to activate the drug. Visudyne therapy uses a specially designed laser that produces the low-level, nonthermal 689nm light required to activate the drug.
The product is generally well tolerated and has an excellent safety profile. Potential side effects include injection site reactions, headaches, blurring, decreased sharpness and gaps in vision and in 1 percent to 4 percent of patients a substantial decrease in vision with partial recovery in many patients.
Visudyne therapy is being co-developed for various ocular conditions. It is approved in 31 countries for treating AMD.