PRO 140 Results for HIV Suppression Nearing Announcement


The monoclonal antibody — a once-weekly injection endorsed by actor Charlie Sheen — has been undergoing current clinical phases for over 2 years.

Nader Pourhassan

Humanized monoclonal antibody PRO 140 has been touted for its potential by 2 different companies about a decade now.

The human immunodeficiency virus (HIV) treatment was acquired by biotechnology company CytoDyn 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 (pictured), PhD, CytoDyn president and chief executive officer, was footing for a larger idea. 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, Schooley told him if he wanted to make the next drug “a game changer, it has to be monoclonal,” Pourhassan said.

The efficacy results from 1 of 2 PRO 140 clinical trials should be announced in the next month, according to CytoDyn. What Pourhassan projects is, indeed, a game-changing treatment: 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 HIV to infect host cells. Paul J. Maddon, MD, PhD, the inventor of PRO 140, was credited by Pourhassan as one of the forefront researchers in CCR5’s role in HIV treatment in 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.

It is currently undergoing 3 trials for HIV treatment. Two of these Phase II-B/III trials compared the treatment versus current standard-of-care Highly Active Antiretroviral Therapy (HAART). One trial tests the treatment in part of combination therapy with antiretroviral therapy (ART), while the other tests PRO 140 as a long-term monotherapy.

The treatment additionally provides a blanket: patients could miss a treatment for up to 3 days, Pourhassan said. The efficacy of the once-weekly treatment is everything Pourhassan believes patients want.

“Many patients said they’d love to have an injection only per week, not a combination of injection and pills,” Pourhassan said. “Eight of our patients have almost gone 3 years with a simple injection per week.”

A notable addition to the trial was a volunteer patient: actor Charlie Sheen, who publicly announced being HIV positive in November 2015.

Sheen reached out to CytoDyn last year, Pourhassan said. 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 stipulation he followed US Food and Drug Administration (FDA) regulation for the trial.

Sheen has been taking the treatment for 15 months now, Pourhassan said. In text message conversations, the actor has thanked 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,” Pourhassan said.

CytoDyn is also investigating PRO 140’s utility as an immunology treatment, currently pursuing clinical studies for its efficacy on colon cancer, multiple sclerosis (MS), and graft versus host disease (GvHD). Studies on its treatment for GvHD have reached a Phase II trial thus far.

In trials, researchers have been able to apply human bone marrow with Pro 140 into mice subjects without rejection — complying to an FDA request that Pourhassan said of which he was initially uncertain. These results were considered “stunning” by its researchers.

“If we can eliminate GvHD that could be an immediate (FDA) approval,” Pourhassan said.

Animal studies for MS and cancers have also returned early positive results, Pourhassan said, and the GvHD Phase II study results will soon be submitted to journals.

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,” Pourhassan said.

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