VANCOUVER, Wash.—Targeted toward ceasing the transmission of human immunodeficiency virus (HIV) while streamlining patient treatment, biotechnology firm CytoDyn recently reported that its lead candidate PRO 140 has documented a 98-percent success rate in a Phase 2b clinical trial. If PRO 140 shows positive results in its upcoming Phase 3 trial, the first self-injectable antibody for HIV could go commercial in 2017—and vastly change the way HIV patients take their medicine.
The National Institutes of Health (NIH) has shown its faith in PRO 140 by providing more than $28 million in grants for the development of the antibody. More than 1.2 million individuals are infected with HIV in the United States, with new infections surpassing 50,000 annually; an estimated 25 percent are unaware of their infection. Worldwide, 36 percent of the population need antiretroviral therapy, with 33.4 million infected individuals and 2.7 million new infections per year.
“Results from six Phase 1 and Phase 2 human clinical trials have shown that PRO 140 can significantly reduce viral load in people infected with HIV,” Dr. Nader Pourhassan, CytoDyn president and CEO, stated in an August 18 news release. “Our Phase 3 protocol provides for an upcoming 25-week study with 300 HIV-positive patients. Selection of clinical sites, IRB approvals, patient screening and other administrative matters are underway and expected to be completed in time for the first patient (in Phase 3) to be dosed in the third quarter of this year.”
Pourhassan tells DDNews that if approved, PRO 140 could serve as a substitute to the current HIV patient drug regimen of swallowing “anywhere from seven to 35 pills per week or taking from one to five pills a day.” PRO 140 has been successful in the previous Phase 2 trial using only the injectable to treat the disease and not allowing HIV patients to take their pill regimen.
“We believe our treatment substitution study has the potential to provide a drug holiday to patients from their daily pill regimen,” Pourhassen said. “PRO 140 could be the key to maintaining viral load suppression in the absence of pills. If the [Phase 3] study has a positive outcome, we believe this may address a significant unmet medical need and have high patient acceptance.”
Pourhassan wouldn’t go as far as calling PRO 140 a miracle drug, but “Considering PRO 140 has almost no toxicity or side effects, having the FDA acknowledge this fact in a letter to us and giving PRO 140 a fast-track status, I would say this product could make millions of HIV patients’ quality of life much better,” Pourhassan says. “CytoDyn purchased PRO 140 from Progenics more than 12 years ago, developing this product and receiving over $28 million from the NIH due to all the spectacular results PRO 140 kept getting.”
PRO 140 works by blocking the HIV co-receptor CCR5 on T cells, preventing viral entry, while effectively reducing viral loads by as much as 1.8log with one dose per week, according to CytoDyn. If the HIV patient’s viral load is completely suppressed, the transmission rate becomes almost zero.
The transmission of HIV, a highly infectious disease, “goes to almost zero when the viral load reaches a complete suppressed level,” Pourhassan notes. “PRO 140 can and has demonstrated keeping the viral load suppressed in HIV patients without taking pills.”
In the Phase 2b study, CytoDyn’s primary objective was to assess the efficacy of PRO 140 monotherapy for the maintenance of viral suppression in HIV patients who are stable on combination antiretroviral therapy, known as HAART (highly active antiretroviral therapy), but need or wish to discontinue HAART therapy temporarily, Pourhassan explains.
About 85 percent of the patients who are HIV positive in the United States and are not very experienced in treatment have a strain of HIV that is called R5, he adds. The R5 strain binds to CCR5 in order to enter the CD4 cell. However, the other 15 percent mostly have a small amount of X4 virus in addition to R5, which is called dual/mix virus. PRO 140 does not work on dual/mix viruses.
“Globally, HIV transmission rate is high,” Pourhassan says. “We definitely think PRO 140 can help decrease those numbers. Our long-term goal is for PRO 140 only to provide monotherapy for all HIV patients who are R5 exclusive.”
Phase 3 trials are expected to be conducted in more than 30 U.S. sites. The company plans to submit its New Drug Application for final approval of PRO 140 in November 2016. PRO 140’s previous fast-track designation carries a possibility of accelerated approval for the injectible.