Revolutionary Medication for Multidrug Resistance

Developed by Theratechnologies Inc, ibalizumab, is the first long-acting biologic injectable to treat multidrug resistant HIV. 

“It’s actually really exciting,” says Yale School of Medicine’s Dr. Brinda Emu, one of the study’s authors. She says ibalizumab, a monoclonal antibody, binds to CD4 receptors, preventing HIV from attaching. Other monoclonal antibodies have targeted CCR5, but targeting CD4 is “a completely new mechanism of action; and because of this, it has no cross resistance with any other antiretrovirals out there.” This is great news for those with HIV resistance, as building resistance to one drug can make all other drugs in that class ineffective. 

Emu says that “all of the other approved molecules out there are small molecules, so they are metabolized quite quickly.” But IBA is larger and has a longer half-life, making it well suited for biweekly administration.

When paired with optimized antiretro-viral therapy, IBA offers new hope to those with the most difficult cases of HIV, who previously had “limited or no remaining options to treat their infection,” Dr. Jacob Lalezari, of Quest Clinical Research told Plus. 

Phase III trial participants had been HIV-positive on average 20 years and, Emu says, “Over 50 percent had exhausted three classes of drugs, 35 percent had exhausted four classes of drugs, and 15 percent of participants had actually exhausted all antiretrovirals — meaning they were resistant to everything that’s been approved.”

After a single week, IBA was already proving effective in decreasing viral loads. Researchers later “optimized” participants’ antiretroviral regimens, and those no longer susceptible to any of the HIV drugs on the market were also given a booster of fostemsavir (another new attachment inhibitor). 

As part of combination therapy IBA proved effective for the majority of study participants, who experienced both reductions in viral loads and increases in the number of T cells. Even better, 43 percent of study participants were able to lower their viral loads to undetectable levels, a remarkable feat given how difficult their HIV had become to treat.