Product will combine Gilead’s Truvada and Tibotec’s NNRTI candidate in Phase III studies.

Gilead Sciences and Tibotec Pharmaceuticals are joining forces to develop and market a once-daily pill for HIV. The fixed-dose antiretroviral regimen will contain Gilead’s Truvada® (emtricitabine and tenofovir disoproxil fumarate) and Tibotec’s investigational non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC278 (rilpivirine hydrochloride, 25 mg) for treatment-naïve individuals. Tibotec is currently studying the combination in Phase III trials.

Gilead will assume the lead role in the manufacturing, registration, distribution, and commercialization worldwide excluding Japan and the developing world. Tibotec has the right to co-promote in Gilead’s regions and remains responsible for the commercialization of TMC278 as a stand-alone product.

“Based on the deal terms, it appears that Gilead had the dominant hand at the negotiating table, as it reads to us more like a licensing agreement than a partnership,” according to Joshua Schimmer, M.D., and Steve Y. Yoo, biotech equity research analysts at Leerink Swann.

If approved, the new product would become the second complete antiretroviral treatment regimen for HIV available in a single tablet taken once daily. The first and currently the only such therapy is Gilead’s Atripla® (efavirenz 600 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg). It was approved by the FDA in 2006. Both Atripla and the new fixed-dose combination contain an NNRTI backbone of Truvada.

Gilead’s current HIV franchise comprises Viread, Truvada, and Atripla. It faces patent expiries from 2017 to 2021. While it is difficult to assign value to the new combination therapy being developed in the absence of Phase III data, expected in 2010, Dr. Schimmer and Yoo say that the deal gives them some comfort that Gilead’s lead role in HIV drug commercialization today will provide the company with opportunities to sacrifice the efavirenz portion of Atripla in exchange for Truvada’s presence well beyond its patent expiry.

The efavirenz component of Atripla is 600 mg, whereas the TMC278 dose in the combination therapy being developed will be 25 mg, add Dr. Schimmer and Yoo. “Therefore, the resulting pill may be smaller with lower patient discomfort. Additionally, ‘278’s CNS side effects appear less pronounced. The Phase II ‘278 study did show QT prolongation at higher doses and somewhat lower efficacy at the 25 mg/d dose.”

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