In May 2007, results from the phase I clinical trial of the drug demonstrated "potent, rapid, prolonged, dose-dependent, highly significant antiviral activity" for PRO 140.

[6] The report discloses that a single 350mg subcutaneous injection of PRO 140 resulted in a HIV-1 RNA viral load reduction greater than 0.5log or 68% within one week compared with those who received a placebo.

On February 18, 2019, CytoDyn announced it will begin 8 pre-clinical studies on melanoma, pancreatic, breast, prostate, colon, lung, liver, and stomach cancer.

On November 23, 2018, CytoDyn received FDA approval of its IND submission and allowed to initiate a Phase 1b/2 clinical trial for metastatic triple-negative breast cancer (mTNBC) patients.

In May 2019, the U.S. Food and Drug Administration (FDA) granted Fast Track Designation for Leronlimab (PRO 140) for use in combination with carboplatin for the treatment of patients with CCR5-positive mTNBC.

If successful, the data from treatment-naïve mTNBC patients could serve as the basis for potentially seeking accelerated US FDA approval.

[9] On November 11, 2019, CytoDyn reported that the first TNBC patient injected under its naïve protocol (not previously treated for triple-negative breast cancer) demonstrated significantly reduced levels of circulating tumor cells (CTCs) and decreased tumor size at two-week and five-week observation intervals compared to baseline observations.

CTCs are a potential surrogate endpoint in oncology trials, with reduced levels suggesting long-term clinical benefit.

[medical citation needed] On December 15, 2020, CytoDyn reached full enrollment in its Phase 3 registrational trial for patients with severe-to-critical COVID-19.

The results showed a reduction in the primary end point of mortality of 24 percent after 28 days compared to the current standard of care.