Test Shows One AIDS Eye Drug Is Better : Health: Those taking a newly approved treatment for infection are unexpectedly found to live longer than those given a standard treatment.
A study designed to compare two drugs used to treat a sight-threatening condition common to AIDS patients has unexpectedly found that patients taking one of the drugs lived longer than those given the second, federal health officials announced Monday.
AIDS patients taking the recently approved foscarnet lived an average of four months longer than those who were taking ganciclovir, which has been on the market since 1989. Both drugs are used to treat cytomegalovirus retinitis, a serious eye infection that often leads to blindness and afflicts 20% of all persons suffering from AIDS.
“These results suggest that, for many patients with AIDS and CMV retinitis, foscarnet may be a better initial treatment than ganciclovir,” said Dr. Douglas Jabs, associate professor of ophthalmology at the Johns Hopkins School of Medicine, who chaired the study sponsored by the National Institutes of Health.
An independent scientific board monitoring the study found the interim results so compelling that earlier this month it recommended suspending the trial and telling investigators and patients participating in the study of the findings. Moreover, a “clinical alert” describing the results was also sent to more than 40,000 physicians in the United States who care for persons with AIDS.
After the development of CMV retinitis, which typically occurs in advanced stages of AIDS, patients have a life expectancy of about eight months. In this study, however, patients taking foscarnet lived an average of 12 months.
The study showed that both drugs were equally effective in stopping the progression of CMV retinitis and preserving vision in patients newly diagnosed with the eye infection.
Initially, researchers speculated that the reason for the increased longevity in patients taking foscarnet was related to the fact that many patients on ganciclovir either must stop taking, or at least reduce the dosage of, AZT, an antiviral drug that attacks the underlying viral condition.
Both AZT and ganciclovir suppress production of white blood cells by the body’s bone marrow and often cannot be taken together. Foscarnet is less likely to suppress white blood cell production and, therefore, can be taken concurrently with AZT.
But further analysis of the data showed that patients on foscarnet who were taking antiviral drugs other than AZT--or no antiviral drugs--also showed the same benefit, the researchers said.
A total of 240 patients with AIDS and previously untreated CMV retinitis participated in the trial between March, 1990, and October, 1991, at 12 clinical centers nationwide, including UCLA, UC San Diego, and UC San Francisco. Under the study protocol, patients who suffered serious adverse reactions to the drug they were taking were allowed to change to the other drug.
Syntex Corp., of Palo Alto, the manufacturer of ganciclovir, called the study results “difficult to interpret because substantial numbers of patients were switched from ganciclovir to foscarnet.”
But Jacobson, of UC San Francisco, said that when researchers “looked at people who crossed over from ganciclovir to foscarnet or vice versa, they saw shorter survival in people who were always on ganciclovir and never crossed over than in any of the other groups who crossed, or who stayed on foscarnet.”
While AIDS organizations hailed the study findings, they expressed concern that the news would result in a price increase. Foscarnet costs $58 a day, or more than $20,000 a year. Like ganciclovir, which costs about $8,000 a year, the drug must be administered intravenously. Foscarnet is manufactured by Astra Pharmaceutical Products Inc. of Westborough, Mass.
