Phase 3 Trial for Novel HIV Drug Begins Enrollment

New class of HIV medications called viral-entry inhibitors protect healthy cells from viral infection.

The first patient has been enrolled in a phase 3 trial of the HIV drug PRO 140 under a newly revised trial protocol that was approved by the FDA.

PRO 140 is part of a new class of HIV/AIDS therapeutics called viral-entry inhibitors, which protect healthy cells from viral infection. The investigational drug is a humanized IgG4 monoclonal antibody directed against the molecular portal CCR5.

PRO 140 blocks the predominant HIV (R5) subtype entry into T cells by masking the CCR5. The modified protocol for the trial caused a 50% reduction in enrollment, which dropped to 150 participants.

Furthermore, the enrollment criteria became more relaxed, giving HIV-infected individuals the opportunity to enter the study before confirmation of the R5 strain of HIV.

“We expected to enroll subjects at a much faster pace under this newly modified protocol, which allows for those with HIV viral load over 400 cp/mL to be treated with PRO 140 and OBT without waiting for their tropism test results,” said Nader Pourhassan, PhD, President and CEO of CytoDyn. “The prior protocol required that study subjects continue on failed ART while waiting for validation of the R5 strain, which could take several weeks and was a deterrent to enrollment. We have shown that PRO 140 is safe for HIV-infected patients with dual mix or X4 exclusive strains of HIV in our completed phase 2b monotherapy clinical trial.”

The phase 3 trial is a multicenter, randomized, combination study to evaluate the safety and efficacy of PRO 140 in combination with standard of care antiretroviral therapy (ART) in HIV patients who are treatment experienced, and who are failing ART therapy.

The trial will be split into 2 parts, with the first part being a double-blind treatment where patients are randomized to receive either weekly subcutaneous injection of PRO 140 or placebo in combination with the failing ART regimen for up to 1 week. During the week, each of the participants will be evaluated for HIV-1 genotypic drug resistance and a newly developed optimized ART regimen.

In part 2 of the study, participants will continue treatment with PRO 140 or placebo in combination with the optimized background therapy (OBT) for up to an additional 3 weeks, when the HIV co-receptor tropism assay results become available. Participants will then be switched to a 24-week, open-label period.

Individuals with R5 virus will be the only participants treated with OBT and PRO 140, and the participants with X4 or dual/mixed-tropic virus will be given OBT alone during the 24-week, open-label period.

“We are excited to quickly enroll our first subject following FDA-clearance of the modified protocol and we anticipate being able to announce topline findings on the primary endpoint in 2017,” Pourhassan said.