CytoDyn, a biotechnology company that has been testing a monoclonal antibody called PRO140 in HIV infected patients,  have released some very exciting results revealing that the first group of patients, have now reached one year of viral suppression whilst having weekly injections of PRO 140 and not taking any antiretrovirals. This is a real milestone, because as PRO 140 is not really a drug it has almost no toxicity, unlike most of the commonly used antiretrovirals. It also doesn’t interfere with immune responses.

PRO 140 is a monoclonal antibody and a new type of HIV drug being investigated. It belongs to a class called viral entry inhibitors and aims to protect healthy cells from infection with HIV. It specifically works for the strain of HIV that uses CCR5 as an entry point. In simple terms this antibody attaches to the CCR5 receptor that would normally allow the HIV to enter the cell. In doing so it blocks HIV from entering the cells. Also of importance is that it does not affect the immune response, it has been extensively tested and has been effective in reducing or suppressing viral loads, with very few side effects.

The Phase 2b study in the initial group of patients finished in January 2015, but patients on the study who did well, were allowed to continue with weekly injections of PRO 140. They were taken off their antiretrovirals and now a year later these patients still have a suppressed viral load. All the patients have reported feeling better whilst on the injections, compared to their daily tablets, with very few side effects noted and an improved quality of life.

The company has started a Phase 3 trial with 300 patients who will be monitored over 25 weeks and have also requested permission from the FDA for a Phase 3 trial for long term PRO140 monotherapy.