North American pharma company CytoDyn has announced that its primary product leronlimab exceeded expectations as a monotherapy for human immunodeficiency virus (HIV).

The company has published new data that shows a weekly 525mg and 700mg dose of leronlimab led to a 90% response rate in HIV-infected patients who made it through ten weeks of monotherapy without virologic failure. Approximately 30% of the 525mg group and 17% of the 700mg group failed the first ten weeks of monotherapy.

Those patients taking 525mg dose who reached the ten week mark without virologic failure have reached an average of 32 weeks with sustained viral load suppression.

Cytodyn is in the process of submitting a biologics license application (BLA) to the US Food and Drug Administration (FDA) for a 700mg dose leronlimab in combination with standard anti-retroviral therapies for HIV. This follows the combination therapy being granted fast track designation and rolling review by the FDA.

The company believes that FDA approval of a leronlimab combination therapy could serve as a solid foundation for a potential label expansion to include leronlimab as a monotherapy.

CytoDyn president, CEO and director Dr Nader Pourhassan said: “If leronlimab is proven to be a successful monotherapy and is approved by FDA, it would be a game changer for HIV patients, offering a safe, highly effective, durable, once weekly treatment option.

“We are excited that our response rate with the 525 mg and 700 mg dosages is close to 90% for those patients who pass the first 10 weeks of monotherapy without virologic failure.

Leronlimab is an investigational humanised IgG4 monoclonal antibody that blocks the receptor CCR5, which has roles and implications in HIV infection, cancer tumour metastases and immune signalling, hence why this drug has multiple indications.

In HIV, the drug masks CCR5, meaning the predominant HIV subtype R5 cannot enter and infect healthy T cells.

In order to help optimise leronlimab dosages for HIV patients in the future, CytoDyn is collaborating with diagnostics company IncellDx ’s CEO Dr Bruce K. Patterson, who is an expert in CCR5. The companies will use laboratory tests to match doses to the individual CCR5 receptor density of each patient.

Pourhassan said: “We believe HIV patients who have R5-tropic virus may respond to monotherapy with a different dose structure depending on their CCR5 density of each T-cell. We will explore a CCR5 receptor occupancy test and genotyping tests for each patient prior to initiating monotherapy with the goal of determining the right dose for each patient.

“If we are successful, it would represent a major step forward in personalized medicine for treatment of HIV patients.”