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Foscarnet and Ganciclovir Compared as Treatment for CMV Retinitis

October 21, 1991

Results from a large, multicenter clinical trial show that patients with AIDS treated for cytomegalovirus (CMV) retinitis, a serious eye infection, with the antiviral drug foscarnet, lived longer than those who received the standard treatment for CMV retinitis, ganciclovir. CMV retinitis is a potentially blinding disease of the retina that affects about 20 percent of people with AIDS.

Trial results show that foscarnet and ganciclovir were equally effective in halting the progression of CMV retinitis and preserving vision in patients newly diagnosed with eye disease.

The Foscarnet-Ganciclovir Cytomegalovirus Retinitis Trial, a randomized, multicenter clinical trial, is supported by the National Eye Institute, a component of the National Institutes of Health. It was conducted in collaboration with the AIDS Clinical Trials Group sponsored by the National Institute of Allergy and Infectious Diseases at NIH.

According to Douglas Jabs, M.D., associate professor of ophthalmology at The Johns Hopkins School of Medicine and chairman of the study, “These results suggest that, for many patients with AIDS and CMV retinitis, foscarnet may be a better initial treatment than ganciclovir.”

After the development of CMV retinitis, patients with AIDS have a life expectancy of about eight months. In this study, patients taking foscarnet lived an average of 12 months, four months longer than patients taking ganciclovir. The difference in mortality between patients treated with foscarnet and those treated with ganciclovir cannot be fully explained by the differential use of zidovudine (AZT) or other anti-retroviral drugs by patients in these treatment groups. Nor could the difference in survival between study patients treated with foscarnet and those who received ganciclovir be explained by variations in disease severity between the two patient groups at the time they entered the study, or to other chance factors.

AZT generally cannot be taken in full doses concurrently with ganciclovir because both drugs have the side effect of suppressing the production of white blood cells. In the past, this incompatibility has forced AIDS patients with CMV retinitis to choose between taking ganciclovir to try to save their vision or opting to take AZT in the hope of prolonging their lives. Foscarnet is less likely to suppress white blood cell production and therefore can be taken concurrently with AZT.

It is possible that improved survival in patients taking foscarnet could be a combined effect of foscarnet and AZT against HIV, as some laboratory studies have suggested, according to Curtis L. Meinert, Ph.D., professor of epidemiology at The Johns Hopkins School of Public Health and director of the study’s coordinating center. However, he cautioned that the results of this study are only applicable to people with AIDS who have CMV retinitis.

Carl Kupfer, M.D., director of the National Eye Institute, said, “The findings from this study underscore the importance of conducting randomized, controlled trials that compare treatments for the ocular complications of AIDS, and the importance of collaboration between ophthalmologists and infectious disease specialists.”

While study patients taking foscarnet generally lived longer than those taking ganciclovir, in a small group of patients who entered the study with decreased kidney function, those taking ganciclovir lived longer.

The study’s Policy and Data Monitoring Board–an independent group of physicians, biostatisticians, and ethicists–recommended on Oct. 7 that the treatment protocol for the trial be suspended, and that study investigators and patients be notified of the findings. Where medically appropriate, study patients will be offered an opportunity to switch from ganciclovir to foscarnet. Foscarnet was recently approved by the Food and Drug Administration for the treatment of CMV retinitis.

Because of the important implications of these results, the National Eye Institute and study investigators decided that they should be released to the public prior to the publication of a detailed scientific report in a medical journal. A clinical alert describing these findings was sent last week to more than 40,000 physicians and others who care for patients with AIDS.

“The rapid release of this information underscores our commitment to making clinically relevant research results available to the public quickly,” said Assistant Secretary for Health James O. Mason, M.D., who heads the Public Health Service.

The National Eye Institute is the principal federal agency for the support of basic and clinical research on the prevention, diagnosis, and treatment of vision disorders. The NIH is one of the eight Public Health Service agencies within HHS.

Background Information on the Trial

The Foscarnet-Ganciclovir CMV Retinitis Trial was designed to evaluate the relative efficacy and safety of foscarnet and ganciclovir for the initial treatment of CMV retinitis in patients with AIDS.

A total of 240 patients with AIDS and previously untreated CMV retinitis were enrolled in the study between March 1990 and October 1991 at 12 clinical centers nationwide (see attached list). Ninety-two percent of patients were men and 8 percent were women. Eighty-one percent of patients were gay men, and the other 19 percent of participants included those who contracted the AIDS virus from intravenous drug use, blood transfusions, or through heterosexual Contact. Thirteen percent of the patients were black and 14 percent were Hispanic.

Both ganciclovir and foscarnet were administered as intravenous solutions. Patients underwent an intensive two-week induction period to bring the CMV retinitis under control, receiving either 60 mg/kg of foscarnet every eight hours, or 5 mg/kg of ganciclovir every 12 hours. Following this induction phase, patients were given either 90 mg/kg daily of foscarnet, or 5 mg/kg daily of ganciclovir to protect against reactivation of the infection.

Under the study protocol, patients who had serious adverse reactions to the drug they were taking, or for whom the drug appeared to be ineffective, could switch to the alternative drug.

The Foscarnet-Ganciclovir CMV Retinitis Trial was conducted as part of a collaborative clinical research project called the Studies of the Ocular Complications of AIDS (SOCA). The purpose of SOCA is to facilitate the evaluation of promising drugs against CMV retinitis and other ocular complications of AIDS.

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Studies of Ocular Complications of AIDS Foscarnet-Ganciclovir Cytomegalovirus Retinitis Trial: 1. Rationale, Design, and Methods. Aids Clinical Trials Group (ACTG). Control Clin Trials. 1992 Feb. PubMed