KEY POINTS Leronlimab or PRO 140 is a humanized monoclonal antibody originally developed as a potential treatment for HIV

It's drawn attention as a candidate COVID-19 treatment because of its ability quell the “cytokine storm"

“The results are impressive,” said CytoDyn CEO Dr. Nader Pourhassan

Another experimental coronavirus drug currently being tested in the United States as a treatment for COVID-19 has shown "impressive" results, but in a small observational study.

The drug is PRO 140 -- better known as leronlimab -- developed by CytoDyn Inc. PRO 140 is a humanized monoclonal antibody originally developed as a potential treatment for HIV infection. A CCR5 antagonist, leronlimab interferes with HIV's ability to enter the cell. It's a viral-entry inhibitor targeting HIV and breast cancer, and works against the CCR5 receptor found on T lymphocytes of the human immune system.

Leronlimab has drawn attention as a potential COVID-19 treatment because of its ability to quell the “cytokine storm" that causes the immune system to go haywire, leading to patient death. Also called the cytokine release syndrome, this immune response occurs when large numbers of white blood cells are activated and release inflammatory cytokines, which activate yet more white blood cells repeating the cycle.

Leronlimab is already being investigated in phase two clinical trials as a treatment for HIV and has been awarded fast-track approval status by the U.S. Food and Drug Administration (FDA).

The COVID-19 trial for leronlimab involved 10 patients enrolled in Emergency Investigational New Drug treatments at Montefiore Medical Center, the academic medical center and the primary teaching hospital of the Albert Einstein College of Medicine in the Bronx, New York City. It showed leronlimab reducing the plasma viral load (the amount of coronavirus in the blood) and restoring the immune system of COVID-19 patients.

“The results are impressive,” said CytoDyn CEO Dr. Nader Pourhassan during a conference call Monday.

CytoDyn earlier revealed leronlimab had shown a “very promising” response in COVID-19 patients with mild-to-moderate symptoms.

Dr. Bruce Patterson, CEO of diagnostic specialist IncellDX, affirmed leronlimab did decrease plasma viral load while also restoring immune cells. He said his lab performed a blood-sample analysis of the first 10 COVID-19 patients.

“That is remarkable for one drug to restore the immune system and decrease the viral burden in these patients,” noted Dr. Patterson. “That is what gives us great hope and great excitement about leronlimab going forward in these trials.”

CytoDyn has been enrolling patients in two clinical trials for COVID-19. One is a Phase 2 randomized clinical trial for mild-to-moderate COVID-19 patients in the U.S. The other is a Phase 2b/3 randomized clinical trial for severe and critically ill COVID-19 patients in several hospitals throughout the country.