Taking A Closer Look at Humanized Monoclonal Antibody PRO 140 for HIV Treatment


Nader Pourhassan, PHD, president and chief executive officer of CytoDyn, the biotechnology company that acquired PRO 140, offers insight into the antibody as treatment for HIV.

A staggering 36.7 million individuals are living with HIV worldwide, and once an individual is infected, they have it for life. Having safe, effective treatment available is what allows these individuals to live as long, and for the most part, as healthy, as their non-infected counterparts.

One such treatment option, humanized monoclonal antibody PRO 140, “belongs to a new class of HIV/AIDS therapeutics,” according to biotechnology company CytoDyn, who acquired the antibody in July 2012, from original developer Progenics Pharmaceuticals.

CytoDyn paid an initial $3.5 million — with supplemental clinical milestone payments — for the investigational treatment. It was a price that Nader Pourhassan, PhD, CytoDyn president and chief executive officer, was footing for a larger idea. Dr. Pourhassan recently recalled a conversation with colleague Robert T. Schooley, MD, division head and professor of medicine in the Division of Infectious Disease’s Department of Medicine at the University of California, San Diego.

While discussing future HIV drugs, Dr. Pourhassan said that Dr. Schooley told him if he wanted to make the next drug “a game changer, it has to be monoclonal.”

Why might monoclonal antibodies be a gamechanger? Researchers believe that they "hold promise as long-acting therapies for people with limited treatment options due to drug resistance."

The efficacy results from 1 of 2 PRO 140 clinical trials should be announced in the next month, according to CytoDyn. What Dr. Pourhassan projects is a once-weekly subcutaneous self-injection antibody that protects healthy cells from HIV infection by binding to the C-C chemokine receptor type 5 (CCR5).

CCR5 is a white blood cell surface protein used by the virus to infect host cells. Paul J. Maddon, MD, PhD, the inventor of PRO 140, was credited by Dr. Pourhassan as one of the forefront researchers in CCR5’s role in HIV treatment for the past decade.

In previous trials, PRO 140 has been shown to reduce HIV viral load in the body, while maintaining a long-term reduction, according to CytoDyn. Patients observed in such trials have been on the treatment for over 2 years during the study’s extension, and have reported minimal adverse effects and toxicities—and no viral resistance.

The treatment also provides a buffer: patients could miss a treatment for up to 3 days, according to Dr. Pourhassan. “Many patients said they’d love to have an injection only per week, not a combination of injection and pills,” he stated. “Eight of our patients have almost gone 3 years with a simple injection per week.”

A notable addition to the trial was volunteer patient, actor Charlie Sheen, who publicly announced his HIV-positive status in November 2015.

Sheen reached out to CytoDyn last year, Dr. Pourhassan shared. At the time, his treatment included 4 weekly pill drugs, and he expressed interest in participating in the PRO 140 clinical trial. After consideration from advisors and the company board, he was allowed to participate under one stipulation: he had to follow the US Food and Drug Administration (FDA) regulation for the trial.

Sheen has been taking the treatment for 15 months now, according to Dr. Pourhassan. In fact, in text message conversations, the actor has thanked Dr. Pourhassan for “saving his life.” Those sentiments, coupled with the positive results of ongoing trial patients, is giving researchers affirmation.

“Their testimonies are that their lives have changed,” Dr. Pourhassan shared.

For now, PRO 140’s potential for limited treatment toxicity and use in HIV suppression is at CytoDyn’s forefront.

“We do have something we believe will change the paradigm of HIV treatment,” Dr. Pourhassan concluded.

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