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With 31 HIV drugs on the market, it is getting harder to develop new compounds that improve on existing highly effective antiretroviral therapy regimens, drugmakers say. Just six have been approved since 2004."The bar for bringing on a drug in HIV has gotten higher," said George Hanna, vice president of virology for US medical and HIV early development at New York-based Bristol-Myers Squibb (BMS). "You can no longer bring to market a drug you're going to have to take three times a day. All of a sudden, we're seeing a lot less in the pipeline."
Most existing classes stop HIV from using proteins to enter cells, or block HIV's ability to copy itself once inside. However, the absence of new drug development could spark HIV resistance, leaving patients without ready alternatives, said Scott Hammer, a Columbia University professor of medicine.
Approved in 2006, Gilead's Atripla, combining Gilead's Truvada (emtricitabine and tenofovir) and BMS's Sustiva (efavirenz), is the most widely used AIDS treatment. The last drugs in new classes, Pfizer Inc.'s CCR5 blocker Selzentry, and Merck & Co.'s integrase inhibitor Isentress, were introduced in 2007.
Three years ago, seven HIV drugs were in final testing ahead of regulatory approval. None are on the market today, though two remain in the third phase of testing. The number of AIDS drugs in various development stages has dropped from 100 in 2006 to about 60 today, said Courtney Stanton, an analyst with Decision Resources. In just the past year, 10 were discontinued or put on hold. Seven are at the end of development, she said.
In January 2010, Merck abandoned vicriviroc, a drug similar to Selzentry, for treatment-experienced patients, because it did not perform better than existing therapies. With robust treatments available, fewer patients are seeking enrollment into trials, and regulators want longer-term data - 48 weeks rather than 16 weeks.
The Friends of AIDS Foundation is dedicated to enhancing the quality of life for HIV positive individuals and empowering people to make healthy choices to prevent the spread of the HIV virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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