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| |  Exciting Results with Crixivan Could Change Treatment of AIDS WASHINGTON, Jan. 29, 1996 -- Exciting results from new studies with Crixivan(R) (Indinavir sulfate), Merck's investigational protease inhibitor, could change the way doctors treat HIV disease and AIDS, according to a major presentation to leading AIDS researchers at the Third Conference on Retroviruses and Opportunistic Infections. Early data show levels of HIV were reduced so that the AIDS virus could no longer be detected by the currently available assay, after four months of treatment, in about 85 percent of patients taking a triple combination of Crixivan and two other AIDS medications (AZT plus 3TC). This triple combination represents an emerging treatment strategy for HIV disease, made possible by the development of powerful protease inhibitors such as Crixivan. Dr. Emilio Emini, Executive Director of Antiviral Research at Merck Research Laboratories, presented these results today in a "State-of-the-Art Lecture" on protease inhibitors, the first new class of AIDS medications in nearly a decade. "Leaders in AIDS research have theorized that, by adding a very potent protease inhibitor like Merck's Crixivan to other antiretroviral drugs, one could knock down the virus to undetectable levels and significantly reduce its ability to reproduce," said Dr. Emini. "While these are early results, these and other data from new studies to be presented this week are the strongest evidence to date that this approach may work, which could change the standards for AIDS treatment. We are continuing to study the duration of such viral suppression." Merck scientists pioneered research on inhibitors of HIV protease, an enzyme critical to HIV's reproduction, and have now led investigation into the use of Crixivan in different combinations with one or two other available AIDS medications, as well as with Crixivan alone. Two Studies Highlighted Dr. Emini described preliminary data from two new studies to be presented later this week. One three-arm trial compared Crixivan alone, the available antiretroviral agents AZT (Retrovir(R), Glaxo-Wellcome) plus 3TC (Epivir(R), Glaxo-Wellcome) and the combination of all three, among HIV-positive patients who had previously taken AZT. At the study's onset, participants had a median level of virus in the blood of approximately 40,000/ml. In the study, 24 of 26 patients receiving all three medications had HIV levels reduced below detection (<500/ml) after four months, and 13 of 26 (50 percent) taking Crixivan alone also achieved this result, based on the currently available test used to measure the amount of HIV in the bloodstream (Roche PCR assay). Although people treated with the combination of only AZT plus 3TC had their virus lowered, their virus remained detectable after four months. Detailed results from this study will be presented at the conference on Thursday by Dr. Roy Gulick of The New York University School of Medicine. Another study presented by Dr. Emini compared Crixivan, the antiretroviral agents AZT plus ddI (Videx(R), Bristol-Myers Squibb), and the combination of all three, among HIV-positive people who had not previously taken AZT. At the study's onset, patients had a median viral level in the blood of approximately 100,000/ml. In 59 percent of people (13 of 22) receiving all three medications, HIV was reduced below detectable levels (<200/ml with the assay used in this study) after five months. Detailed results from this study will be presented Tuesday at the conference by Dr. Ferdinand Massari of Merck Research Laboratories. In one encouraging case from earlier research discussed in Dr. Emini's presentation, a patient in another trial taking Crixivan alone has maintained an undetectable level of HIV and has remained healthy, for two years. "We are at a pivotal time in the treatment of HIV disease and AIDS, where for the first time, we may be close to achieving almost total suppression of the AIDS virus reproduction in most patients," Dr. Emini said. "We are currently carrying out a large-scale trial to demonstrate the impact of this strategy on clinical outcomes, such as disease progression." Dr. Emini also presented results of earlier trials using Crixivan at various doses. Based on these studies, the optimal dose of Crixivan was determined (800 mg every eight hours), at which maximal anti-HIV activity was achieved. The antiviral activity was enhanced when Crixivan was used in combination with several other available antiretroviral agents. "The critical goal of therapy now should be to reduce viral levels and replication as much as possible, for as long as possible, in as many people as possible," according to Dr. Emini. "To achieve these optimal results, therapy must begin with the most potent and tolerable combination of medications, and in early studies to date, Crixivan has demonstrated its potential usefulness in this approach." In all studies, Crixivan has been generally well tolerated, with nephrolithiasis (defined as flank pain, blood in urine or kidney stones) occurring in 2 - 3 percent of patients in current trials. Patients in current clinical trials are encouraged to regularly drink water to maintain hydration, and the vast majority of patients that experienced nephrolithiasis have continued on therapy. Clinically significant drug interactions have not been seen except with rifabutin and ketoconazole, which have been managed with dose adjustments. "While Crixivan is not a cure for AIDS, these results should be extremely encouraging to doctors and patients," said Dr. Emini. Crixivan is a potent and highly specific compound in a new class of AIDS drugs called protease inhibitors. Unlike earlier AIDS therapies, Crixivan attacks HIV at a different stage in its life-cycle. The promising effects of Crixivan on virus level reductions and CD4 cell recovery, combined with the generally good tolerability seen in ongoing clinical trials, reinforces Merck's commitment to developing Crixivan as rapidly as possible, and Merck is continuing Phase III trials of Crixivan worldwide. Merck & Co., Inc. (NYSE: MRK) is a leading research-driven pharmaceutical products and services company. Merck discovers, develops, manufactures and markets a broad range of innovative products to improve human and animal health. Crixivan(R) is the Merck-registered trademark for Indinavir sulfate. CONTACT: Jan Weiner, 215-652-6462, Michael Watts, 908-423-5491, or Michael
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