May 2007

FDA Panel Recommends Approval of New HIV Drug

In April 2007 an FDA panel of outside experts unanimously recommended accelerated approval of a new medication, maraviroc, proposed brand name Celsentri®. Celsentri® (cells- entry) is an appropriate name because the medication works by blocking the CCR5 receptor that serves as a main doorway for the HIV virus to enter the cell and replicate. Researchers found years ago that people who did not have the CCR5 receptor were resistant to HIV infection or had slow development of HIV to AIDS. This led to the interest in marketing a new line of medications that worked on the human receptor instead of on the virus itself. Though drugs that block the CCR5 receptor have had safety problems, such as liver damage and cancer, studies have not reported significant safety issues with maraviroc. However, panel members suggest the drug’s risks should be studied closely after approval. Other unwanted effects seen with maraviroc are headache, lowered blood pressure, nausea, bladder irritation, and an increased risk for infections such as herpes. 1,2

Maraviroc is a twice-a-day tablet being approved for treatment-experienced patients who have a form of HIV that uses the CCR5 receptor. A test to determine if the HIV strain is CCR5 dominant (meaning the virus uses the CCR5 receptor to enter the cell) will be performed on patients before maraviroc is started. Primary clinical trials showed that viral loads were decreased to undetectable levels in 45% of patients taking maraviroc after 24 weeks compared to 23% of patients taking placebo. 3

Studies have shown that the tablet can be taken with or without food. 4 Drug interactions with efavirenz (Sustiva®) and lopinavir/ritonavir (Kaletra®) have also been noted. Additional studies will need to be conducted to determine the appropriate dose adjustments of maraviroc, especially when taken with other antiretrovirals. 5

According to Katie Laessing from the FDA, the evaluation of maraviroc will likely be completed by the end of next month. 3

Notes
1. Intl AIDS Conf - 15th, 2004. Abstract TuPeB4605.

2. FDA - Pfizer Inc, Maraviroc Tablets NDA 22-128, Antiviral Drugs Advisory Commitee (AVDAC) Briefing Document, April 24, 2007. Available at: http://www.fda.gov/ohrms/dockets/ac/07/briefing/2007-4283b1-01-Pfizer.pdf. PDF - 2,000KB Accessed 04/27/07.

3. Corbett Dooren, Wall Street Journal, April 25 th, 2007.

4. Intl AIDS Conf - 15th, 2004. Abstract TuPeB4489.

5. Conf Retroviruses Opportunistic Infect - 12th, 2005. Abstract 663.

 

 

 

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