Merck & Co said yesterday it has licensed an experimental fusion inhibitor, code-named L’644, to the International Partnership for Microbicides to develop a potential vaginal microbicide.
Microbicides are gels which can be applied prior to sexual intercourse, containing agenst which block HIV from infecting vulnerable cells in the genital area. It is hoped that women will be able to adopt microbicides without having to negotiate their use with male partners, one of the big disadvantages of condoms.
There is increasing interest in the use of antiretroviral drugs within microbicides, following disappointing results from trials of first-generation vaginal microbicides such as cellulose sulphate (UsherCell) and Carraguard.
There is some concern that the incorporation of antiretroviral drugs into microbicides could lead to the development of drug resistance in HIV-positive women, if the compound passed through the vaginal wall into the bloodstream.
Fusion or entry inhibitors such as L’644 may be particularly attractive as a microbicide ingredient because this class of antiretroviral drug is not likely to be widely used in treatment, particularly in developing countries.
Merck’s compound is the sixth antiretroviral agent licensed to the IPM, and follows a similar agreement with Merck that granted IPM a royalty-free license in 2005 to develop another compound, L’167/CMPD167, which belongs to the class of molecules known as CCR5 blockers.
“Merck deserves recognition for its exemplary commitment to HIV prevention research,” says Dr. Zeda Rosenberg, CEO of the International Partnership for Microbicides. “This arrangement for L’644 helps IPM pursue development of compounds that target HIV at many points in the virus’s lifecycle. We’re working toward the day when millions of women around the world will have access to safe and effective microbicides — and partnerships like this will help us get there.”
In addition to Merck, IPM’s pharmaceutical partners include Pfizer, which in January 2008 agreed to allow IPM to develop the CCR5 blocker maraviroc as a microbicide. In December 2006, IPM and CONRAD reached independent agreements with Gilead Sciences to develop tenofovir (PMPA), a nucleoside reverse transcriptase inhibitor.
In October 2005, IPM entered agreements with Merck and Bristol-Myers Squibb to develop CCR5 blocker and entry inhibitor compounds early in development. In March 2004, IPM signed an agreement with Johnson & Johnson subsidiary Tibotec Pharmaceuticals to develop the company’s non-nucleoside reverse transcriptase inhibitor, dapivirine, as a microbicide; IPM expects to put that compound into a Phase III clinical trial late in 2009.