Today, thanks to the advances made in antiretroviral treatment, many people with HIV are living long healthy lives. But there are still many who carry a drug-resistant form of the virus, and for whom the standard therapy is ineffective. Unfortunately for these people, HIV can still be a very debilitating and life-threatening condition. The good news is that researchers and scientists continue to work tirelessly around the clock to find more ways to attack drug-resistant HIV.
Last week, at the 16th European AIDS Conference in Milan, Italy, a representative from ViiV Healthcare reported the discovery of a new experimental HIV attachment inhibitor that was effective in treating people with “highly drug-resistant HIV.” In the BRIGHTE Phase 3 study (in which ViiV was a participating partner), researchers found that a drug called fostemsavir was able to control the viral load in about half the study’s participants, according to a report by NAM's AIDSMap.
Fostemsavir is being developed by ViiV as an agent for use in treatment-experienced people with resistance to several classes of antiretroviral drug. The drug was acquired from Bristol-Myers Squibb along with several other experimental antiretroviral drugs in 2016. Clinical trials of fostemsavir have tested the drug in people with HIV who have two or fewer active classes of antiretroviral drug available to them.
A substantial minority of people living with HIV (most of whom began treatment in the mid-1990s) have been forced to remain on “suboptimal regimens” and have developed resistance to non-nucleoside reverse transcriptase inhibitors, nucleoside reverse transcriptase inhibitors and most protease inhibitors.
Before the discovery of fostemsavir, the only other similar inhibitors of HIV entry — enfuvirtide and maraviroc — had very limited roles in treating HIV. Enfuvirtide is an injectable HIV fusion inhibitor that is prescribed only for people with no other treatment options. Maraviroc is a CCR5 antagonist (it prevents HIV from using the CCR5 receptor on the surface of CD4 cells to gain entry to the cell) and is also used in “treatment-experienced” people. Unfortunately, neither treatment has been very successful in achieving long-lasting viral suppression.
In the study, nearly 300 HIV-positive individuals who had previously experienced “extreme drug-resistance” in the United States, France, and Brazil starting taking fostemsavir. Researchers found that the fostemsavir was able to bind to the HIV gp120 protein, preventing HIV attachment to CD4 cells. Over half of the participants (54 percent) taking fostemsavir achieved virologic suppression (40 c/mL or less) after 24 weeks.
Fostemsavir has been designated a “breakthrough therapy” by the U.S. Food and Drug Administration (FDA) for answering an unmet clinical review and will receive rapid review when submitted for licensing. The FDA is expected to review a licensing application in the first half of 2018.