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FDA Drafts New Rules for Testing and Approval of Combination Regimens for Diseases such as Tuberculosis and HIV

SUMMARY: The U.S. Food and Drug Administration (FDA) recently announced that it is drafting new guidelines for testing and approving multi-drug regimens for life-threatening diseases. A new initiative known as Critical Path to TB Drug Regimens will bring together pharmaceutical companies and others to collaborate on combination regimens for tuberculosis, which is expected to significantly speed up drug development; similar initiative for HIV/AIDS may come together in the future.

By Liz Highleyman

Diseases such as tuberculosis and HIV must be treated with combination therapy in order to fully suppress pathogens and prevent emergence of drug resistance, but testing individual agents in a multi-drug regimen presents challenges.

To date, the FDA has required that each drug in a regimen must be tested and approved individually, with each successive agent added to a background regimen of existing approved drugs. But it can be difficult to demonstrate the independent efficacy of a single agent in a regimen with other active drugs, as shown recently in the case of Merck's investigational CCR5 antagonist vicriviroc.

Gilead Sciences is currently developing a 4-in-1 combination Quad pill in which one of the ingredients -- the experimental boosting agent cobicistat (GS 9350) -- has no anti-HIV activity of its own, and the company plans to seek approval of cobicistat in conjunction with the other drugs.

Now, a public-private collaboration known as Critical Path to TB Drug Regimens has launched to test combinations of investigational tuberculosis drugs from different companies early in the development pipeline. About 10 promising anti-TB candidates from at least 6 antibiotic drug classes are currently in clinical trials or late preclinical development.

The collaboration was created by the Global Alliance for TB Drug Development, the Critical Path Institute, and the Bill & Melinda Gates Foundation, and includes FDA representatives and researchers from several pharmaceutical companies including Anacor, AstraZeneca, Bayer, GlaxoSmithKline, Johnson & Johnson, Novartis, Otsuka, Pfizer, Sanofi-Aventis, and Sequella. GlaxoSmithKline and Pfizer have also formed a partnership, called ViiV Healthcare, to work together to develop HIV therapies.

The new TB collaboration will welcome participation from any company with a promising drug candidate in development, as well as other companies and organizations with the technical expertise or resources to help develop new TB regimens.

The initiative could potentially reduce the time it takes to introduce new combination TB treatments from as much as a quarter century to as few as 6 years, according to the Alliance. The initiative has the commitment of the FDA and regulatory authorities in Europe "to help develop and validate improved, safe, and accurate regulatory pathways to test and register combination TB treatments."

"FDA is absolutely committed to working with partners to speed access to new, safe and highly-effective treatments for TB, which continues to mutate and spread," said FDA commissioner Margaret Hamburg in a press release issued by the Alliance. "This creative approach mirrors FDA's own investments in innovative regulatory science that ensures the best new medical technologies -- including combination therapies -- reach patients as soon as possible."

"With its leadership on TB, FDA is poised to repeat its creative regulatory approach to AIDS drugs in the 1990s, which helped save the lives of millions without compromising drug quality," said Mark Harrington of Treatment Action Group.

Some experts, however, think the approval mechanism for HIV drugs is itself due for an overhaul now that more than 20 antiretroviral drugs are available to build effective combination regimens, making it harder for a new candidates to stand out even if they work as well as existing agents.

For more information about the Critical Path Institute, please visit

For more information about the Global Alliance for TB Drug Development, please visit



Kaiser Family Foundation. FDA Drafts New Rules for Testing, Approving Drug Cocktails; Public-Private Partnership for TB Treatment Development Launched. Kaiser Daily Global Health Policy Report. March 18, 2010.

M Schoofs. FDA Is Easing Way for Drug Cocktails. Wall Street Journal. March 18, 2010.

Global Alliance for TB Drug Development. Global Partners Join Forces to Speed Development of New TB Drug Combinations. Press release. March 18, 2010.
















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