Chiron Vision Receives U.S. Marketing Clearance for Vitrasert Implant to Deliver CMV Retinitis Drug; Vitrasert Is First Drug Delivery Implant For Local, Sustained Therapy of the Eye.

CLAREMONT, Calif.--(BUSINESS WIRE)--March 5, 1996--Chiron Vision Corporation, the ophthalmic business unit of Chiron Corporation (NASDAQ:CHIR), announced today that the U.S. Food and Drug Administration (FDA) has granted marketing clearance for the Vitrasert(TM) Implant, the first drug delivery system to provide local, sustained therapy for the eye.

Vitrasert is indicated for the treatment of cytomegalovirus (CMV) retinitis in people with AIDS. The implant releases ganciclovir (Cytovene(R); Roche Laboratories) to the site of disease in the eye in which it is implanted.

In July 1995, Chiron Vision filed a New Drug Application (NDA) with the FDA based on two independent Phase III trials demonstrating that the Vitrasert ganciclovir implant offers significant improvement over deferred therapy or standard therapy in delaying the progression of CMV retinitis in the treated eye.

CMV retinitis affects an estimated 15 percent to 40 percent of people with AIDS. CMV retinitis usually begins as a white infiltrate within the retina, and can progress rapidly to cause destruction of retinal tissue. Retinal damage can lead to detachment of the retina, occurring in 15 to 29 percent of patients with AIDS-related CMV retinitis, and permanent loss of vision.

"If left untreated, CMV retinitis will eventually progress in all AIDS patients with this potentially blinding disease," commented Baruch Kuppermann, M.D., Ph.D., Assistant Professor, Department of Ophthalmology at the University of California, Irvine. "Early diagnosis of CMV retinitis and prompt, appropriate intervention will continue to be a vital component of AIDS-related care."

Dr. Kuppermann continued, "The sustained, local release of ganciclovir from the Vitrasert implant into the eye lasts six months or more, eliminating the need for a central venous catheter, as used in chronic intravenous treatments. Further, clinicians are increasingly recognizing that direct, sustained delivery to the eye may be the best means to control disease by attaining higher, continuous levels of the drug at the disease site."

Patients with a Vitrasert implanted unilaterally should be continuously monitored for development of disease in the other eye or for development of non-ocular CMV manifestations.

"Based upon this marketing clearance, Chiron Vision will ensure the most rapid availability of this new and important therapy for a tragic condition that robs many people with AIDS of their vision," said William J. Link, Ph.D., Chief Executive Officer of Chiron Vision.

"Today's action by the FDA is the culmination of a model collaboration between the FDA, the National Eye Institute, community-based groups representing HIV-infected people and Chiron Vision. On behalf of all these collaborators, I want to thank the clinical investigators and study subjects whose participation and dedication have made the FDA's action possible."

"The result of six years of testing and development, Vitrasert is designed to benefit a broad range of patient populations, including those who may wish to avoid an indwelling catheter or certain systemic side effects," said Judy F. Gordon, D.V.M., Vice President, Scientific Affairs at Chiron Vision.

"In addition to the striking benefit in delaying progression of retinitis demonstrated in the pivotal trials, our studies have also shown clinical utility in patients whose retinitis has progressed despite systemic treatment or who are intolerant of currently available drugs."

Clinical Trial Results

Data from Chiron Vision's Phase III trial of 188 AIDS patients with newly diagnosed CMV retinitis have demonstrated that time to disease progression was significantly delayed for patients who received Vitrasert, compared with those on intravenous (I.V.) ganciclovir. The study showed that eyes in the primary analysis group treated with Vitrasert had a median time to progression of 216 days, versus 104 days for eyes on I.V. treatment.

In addition, results of a clinical study reported by the National Eye Institute (NEI) in the Archives of Ophthalmology showed that the median time to progression of peripheral CMV retinitis in newly diagnosed patients who received the implant was about 8 months, or 226 days. Those who received no immediate treatment or those assigned to deferred treatment progressed in approximately 15 days.

"The difference in time to progression of retinitis for patients treated with the ganciclovir implant was remarkable, particularly when compared with the time to progression of two to three months reported with currently available systemic therapies," explained Daniel F. Martin, M.D., the study's co-principal investigator and assistant professor of ophthalmology at the Emory University School of Medicine. Dr. Martin also reported that ophthalmic complications were uncommon in the study.

The Vitrasert Implant, surgically placed in the posterior segment of the eye, allows diffusion of drug (ganciclovir) locally to the site of infection over an extended period of months. Implantation normally takes less than one hour, requires only local anesthesia ("nerve block") and is conducted in an outpatient, day-surgery setting.

Immediately following insertion of the implant, most patients experience transient blurred vision in the operated eye, which generally clears within two to four weeks. The implant can be removed when depleted of drug, usually within five to eight months, and a new Vitrasert Implant can be inserted. The implant utilizes technology developed by Paul Ashton, Ph.D. and Thomas Smith, M.D. in association with the University of Kentucky, and was licensed from Control Delivery Systems, Inc.

"Chiron Vision is a leader in the development of innovative products for the surgical correction of vision," said Thomas W. Burns, Vice President, Vitreoretinal Surgery at Chiron Vision. "By introducing Vitrasert, we will expand the ability of ophthalmic surgeons to play a more active role in helping people with AIDS preserve their vision. We also look forward to continuing our efforts with the Roche Group to develop the most effective approach for the care of HIV-infected individuals at risk of CMV infection."

Chiron Vision and F. Hoffmann-La Roche Ltd., Basel are currently collaborating to market and co-promote Vitrasert worldwide. Marketing applications have been filed in Canada and with the Committee on Proprietary and Medicinal Products (CPMP) of the 15- nation European Union.

In addition, an ongoing clinical trial, conducted by Roche Laboratories, is studying Vitrasert in combination with oral Cytovene, recently approved for the prevention of CMV disease. This study will assess potential reduction in risk of developing CMV disease in sites other than the implanted eye. For more information on this study, the public can contact the PROFESSIONAL SERVICES GROUP at Chiron Corporation by dialing 1-800-CHIRON-8 (1-800-244-7668).

Chiron Corporation has a number of programs across its businesses directed at HIV infection as well as the opportunistic infections that frequently plague people with AIDS. On its own and together with the NIAID, Chiron is conducting clinical trials of its cancer drug Proleukin(R) (aldesleukin) interleukin-2 in patients with HIV infection.

Chiron has candidate vaccines for CMV and HIV in Phase II clinical trials, and a vaccine for genital herpes in Phase III trials. Chiron's bDNA probe tests are being used to measure HIV RNA levels in studies to determine the correlation between viral load and disease progress, to monitor therapy, and to help assess the effectiveness of potential new HIV drugs.

Chiron Viagene is conducting a Phase II trial for a gene therapy approach to treating HIV infection. Chiron is well known for its discovery of hepatitis C virus and the subsequent introduction of tests used to screen donated blood and plasma for the potential presence of this infectious agent, and for its development of the first genetically engineered vaccine, for hepatitis B.

Chiron Vision, headquartered in Claremont, California, researches, develops, manufactures and markets products for the surgical correction of vision, including intraocular lenses (IOLs), phacoemulsification instruments, viscoelastics, corneal shapers, excimer lasers and drug delivery systems. Chiron Vision is among the world's leading sellers of IOLs and related products.

Chiron Corporation, headquartered in Emeryville, California, is a diversified, science-driven healthcare company that combines diagnostic, vaccine and therapeutic strategies for managing disease.

Chiron participates in four global healthcare markets: diagnostics, including immunodiagnostics, critical care diagnostics and new quantitative viral probe tests; therapeutics, with an emphasis on oncological, infectious, neurological and cardiovascular disease; pediatric and adult vaccines; and ophthalmic surgical products for the correction of vision. Chiron also conducts research and development in the fields of biological proteins, gene therapy and combinatorial chemistry.

CONTACT: Chiron Vision Corporation

Missy Lowery, 800/352-1891

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Chiron Corporation

Larry Kurtz, 510/601-2476

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Burns McClellan

Lisa Burns, 212/505-1919

Justin Jackson, 415/352-6262

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