By Mary Welch
Gilead Sciences Inc. and Fujisawa Healthcare Inc. received FDA approval to expand the labeling of AmBisome (liposomal amphotericin B) to include the treatment of cryptococcal meningitis in HIV-infected patients.
"This is the second label expansion and we are pleased that we now have a broader label," said Sheryl Meredith, director of corporate communicants for Foster City, Calif.-based Gilead Sciences. "This indication is for an end-stage disease, and it's important that these patients are able to get this drug."
Gilead's partner, Deerfield, Ill-based Fujisawa USA Inc., submitted the supplemental new drug application last July seeking the label expansion.
With this approval, AmBisome is the first lipid agent to receive an indication for cryptococcal meningitis in HIV-infected patients, the company said.
Cryptococcal meningitis is a life-threatening infection of the membranes that line the brain and spinal cord. It can occur when a patient is exposed to the fungus Cryptococcus neoformans. The organism can infect almost all organs, although it most commonly causes diseases of the meninges, skin or lungs. The majority of those with cryptococcal meningitis have immune systems that are damaged by disease, such as AIDS, or suppressed by drugs.
Cryptococcal meningitis is the most common cryptococcal infection in people infected with HIV, affecting 5 percent to 10 percent of the patients. Gilead estimates the market for the new indication is about 733,000 patients in the U.S., Meredith said.
AmBisome was approved as an empiric therapy in August 1997 for the treatment of presumed fungal infections in febrile, neutropenic patients; in patients with Aspergillus species, Candida species and/or Cryptococcus species infections who did not respond to treatment with amphotericin B, and for the treatment of visceral leishmaniasis (a parasitic infection). (See BioWorld Today, Aug. 13, 1997, p. 1.)
It also is recommended for the treatment of patients in whom renal impairment or unacceptable toxicity suggests that conventional amphotericin B should not be used or should be discontinued.
The drug had 1999 revenues of $137 million worldwide, Meredith said.
Amphotericin B, which cures about half of all invasive fungal infections, can cause irreversible kidney damage. However, lipid formulations, such as AmBisome, are designed to lower the toxicities by delivering the drug directly to fungal cells
In February, the FDA approved a labeling supplement that provided data comparing the safety of AmBisome with Abelcet (amphotericin B lipid complex). Abelcet is marketed by The Liposome Co., of Princeton, N.J. (now part of Dublin, Ireland-based Elan Corp. plc). Abelcet has been on the market since 1995 and now is marketed in the U.S. and 25 other countries. In 1999 it had sales of $86.2 million
As a result of the FDA's action, the AmBisome label now includes a claim of superior safety compared to Abelcet in febrile neutropenic cancer patients. Despite the fact that those patients in the clinical trial who received AmBisome had significantly less nephrotoxicty, the possibility of dose-limiting renal toxicity with patients taking AmBisome still exists.
"In our view, AmBisome continues to demonstrate clinical utility in treating various types of severe fungal infections," said Carolyn Pratt, an analyst with Needham & Co. in Boston. "In addition, AmBisome's clinical profile appears to be superior to that of competitor Abelcet, and we expect that the drug will keep capturing market share."
Jon Alsenas, profile manager with ING Furman Selz Asset Management LLC, of New York, agreed the FDA comparison is the key to AmBisome's future success.
"Everyone knows that amphotericin works well against a number of fungal infections," he said. "When the FDA put it on the label that AmBisome was better than its chief rival, that was huge. We expect AmBisome to have a great 2001 and keep gaining market share from Abelcet."
AmBisome was developed by Vestar Inc., of San Dimas, Calif., which later merged with NeXstar Pharmaceuticals Inc., of Boulder, Colo. NeXstar was later acquired by Gilead Sciences in a $550 million stock deal. (See BioWorld Today, Nov. 1, 1994, p. 1; and March 2, 1999, p. 1.)
Gilead Sciences' stock (NASDAQ:GILD) closed Wednesday at $70.937, up $1.062.