New Hope in Fighting Multi-Drug Resistant HIV

A new, long-acting injectable HIV medication offers hope for those who have multi-drug resistant strains of HIV. Early findings from Phase 3 trials show that ibalizumab, a drug developed by Theratechnologies Inc., has been effective in significantly decreasing viral loads after just the first week of treatment. Revealed at ID Week 2016 in New Orleans, the results are based on 40 participants with multi-drug resistant strains of HIV who were given a shot of 2,000 mg of ibalizumab in addition to their failing antiretroviral therapies — or no therapy at all. 

Seven days later, 83 percent had achieved a decrease in their viral loads and 60 percent saw a decrease above 1.0 log10. According to study author Dr. Jacob Lalezari, CEO of San Francisco’s Quest Clinical Research, a “one log decrease in viral load represents a 90 percent decrease in virus.” While that sounds impressive, it wouldn’t make the drug potent enough as a single therapy, but combined into a cocktail with other drugs it will offer effective treatment.
More than 85 percent of participants came to the study with at least one identified mutation, conferring resistance to nucleoside reverse transcriptase inhibitors (like Viread), non-nucleoside reverse transcriptase inhibitors (like Rescriptor), or protease inhibitors (like Lexiva); and more than 60 percent had resistance to at least one integrase inhibitor (like Isentress). On average, the participants’ strains of HIV were resistant to more than 75 percent of all drugs in the NRTI, NNRTI, and PI classes; as well as to one or two drugs from the INI class.  Finally, 50 percent of patients had a strain with resistance to all available drugs from at least three classes of antiretrovirals.

Lalezari tells Plus, “The HIV virus is a complex pathogen that finds ways to elude treatment by mutating to become resistant.”  While only 0.6 percent of all new HIV cases are resistant to three classes of drugs, that’s still thousands of people, who Lalezari says, “have limited or no remaining options to treat their infection.” Because drug resistant strains can also be transmitted to others, there’s pressing need develop new therapies.

That’s what makes ibalizumab potentially so exciting, Lalezari says, “If approved by the FDA, [it] would be the first long-acting biologic to show such efficacy in patients with highly resistant HIV-1."

Furthermore, he says, ibalizumab may help to reduce viral loads in patients whose HIV cannot be controlled by currently- available treatments. "When combined with other agents, ibalizumab could help these patients in dire need of new treatment options, and could change the way multi-drug resistant HIV is managed in the future.”
The biggest news here is that ibalizumab will be the first long-acting non-oral therapy approved for treating HIV. As renowned HIV doctor Dr. David Ho told the 2016 U.S. Conference on AIDS, “Injectables are the future of HIV treatment,” because they take the issue of adherence out of the picture.  “These drugs could become important in combination with other drugs, and could offer a subset of patients an alternative to daily oral therapy," adds Lalezari. 

That’s one reason the Food and Drug Administration declared ibalizumab a “breakthrough therapy,” a designation that speeds up the approval process for new therapies treating serious and life-threatening conditions, when they may provide a substantial improvement over what is currently available.

The last clinical trial required by the FDA—the 24-week ibalizumab Phase III study — wrapped last October, but the final findings were not available as this issue went to print. Still, these initial results are very positive, and Theratechnologies Inc has already started recruiting participants for an “expanded access study,” which will give needy patients (who didn’t qualify for the clinical trial) access to the new drug prior to official FDA approval.