Pfizer’s Antiretroviral Maraviroc Reduces Viral Loads Among People Taking Additional Treatments, Study Says
Pharmaceutical company Pfizer on Tuesday at the 47th Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago presented results of a new long-term study of its antiretroviral drug maraviroc, AFP/Yahoo! News reports. According to the company, data from a 48-week study showed that nearly three times as many HIV-positive people who took maraviroc in combination with a traditional treatment regimen achieved undetectable levels of HIV, compared with those receiving only the traditional regimen (AFP/Yahoo! News, 9/19). Pfizer also said that CD4+ T cell counts significantly were increased among people taking maraviroc, compared with participants who took only the standard regimen (AP/Yahoo! Finance News, 9/18).
FDA in August approved maraviroc, which belongs to a new class of antiretrovirals that could provide an alternative to HIV-positive people who have developed resistance to multiple drugs. FDA gave expedited approval of maraviroc for use in combination with other antiretrovirals. Maraviroc works by blocking a protein, called CCR5, on human immune system cells that HIV uses as a portal to enter and infect the cell. Pfizer has proposed using the drug to treat people with advanced HIV or AIDS who have not responded to other medications. FDA approved maraviroc on the condition that the drug's label include a black-box warning -- the strongest possible advisory. The drug also will have a warning about an increased risk of heart attack. FDA also is requiring Pfizer to conduct further research into the drug's long-term side effects (Kaiser Daily HIV/AIDS Report, 8/7).
Pfizer on Tuesday said the side effects recorded among participants who took maraviroc resembled those experienced by participants who received only the traditional regimen, the AP/Yahoo! Finance News reports. The most common side effects reported included diarrhea, nausea, fatigue and headache. Pfizer also said that maraviroc, sold under the brand name Selzentry, is now on the market across the U.S. and that the company is working with private and public payers to secure coverage and reimbursement, the AP/Yahoo! Finance News reports (AP/Yahoo! Finance News, 9/18). "The safety and durability of response seen with Selzentry ... in our study is reassuring," Jacob Lalezari, director of Quest Clinical Research at the University of California, said, adding, "This drug is an important new weapon for clinicians who treat HIV" (AFP/Yahoo! News, 9/19).
J&J Presents Data on Antiretroviral Prezista
Johnson & Johnson on Tuesday at the ICAAC conference announced that its antiretroviral darunavir, sold under the brand name Prezista, proved as effective in a late-stage trial as Abbott Laboratories' antiretroviral Kaletra in reducing HIV viral loads among people not previously treated for the virus, Reuters reports. For the study, researchers gave Prezista, a once-daily protease inhibitor, to participants along with Abbott's Norvir and Gilead Science's Truvada. A separate group of people was given Kaletra and Truvada. The study showed that HIV decreased to undetectable levels after 48 weeks among 84% of patients taking experimental 800mg doses of Prezista, compared with 78% of those on Kaletra.
The trial was the first to test Prezista among people who previously have not taken other antiretrovirals, Reuters reports. Abbott spokesperson Ilke Arici said the study's findings are somewhat questionable because the trial design did not reflect how the drugs are distributed in real-life medical settings, Reuters reports. Arici said many participants were given a soft gel form of Kaletra, which she said is less effective than a new tablet formulation now widely available in the U.S. J&J spokesperson Pam Van Houten said that most participants taking Kaletra began on the soft gel form but later were switched to tablets after they became available. Van Houten said J&J plans to seek FDA approval by the end of 2007 for the use of Prezista by people never previously treated for HIV (Pierson, Reuters, 9/18).