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Researchers investigate PRO 140 as standalone therapy for HIV
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BOSTON — Findings from a phase 2b trial of PRO 140, a humanized monoclonal antibody, suggest the treatment could be used as a standalone therapy in place of ART for some patients with HIV-1 infection.
“We set out to prove a hypothesis that PRO 140 monotherapy — or single-agent maintenance therapy — after ART can maintain virologic suppression in HIV-infected patients,” Paul J. Maddon, MD, PhD, senior science adviser to CytoDyn, told Infectious Disease News. “And I think that’s what we showed. Patients treated with PRO 140 were able to maintain virologic suppression after discontinuing ART.”
Paul J. Maddon
In a 12-week study, researchers enrolled 40 patients aged 18 years or older who were infected exclusively with CCR5-tropic HIV-1 — a strain that is found in 80% to 90% of patients starting treatment, according to Maddon. The PRO 140 monoclonal antibody was developed to bind to the CCR5 receptor, blocking HIV from infecting target cells.
Virally suppressed patients were asked to replace their daily oral ART regimens with weekly, 350-mg subcutaneous injections of PRO 140. Maddon said many of these patients had been treated with ART for a long time, some even for decades. Those who maintained virologic suppression at 12 weeks with PRO 140 were trained to self-administer the injection for an additional 108 weeks (n = 15).
According to the researchers, 10 of the 15 patients who were allowed to continue monotherapy with PRO 140 after the initial 12 weeks have now achieved virologic suppression for approximately 1.5 years. Maddon said four patients in the extension study experienced virologic failure — three of whom were receiving concomitant medications for concurrent infections, which may have contributed to the treatment failures — and one patient who had a viral load of 40 copies/mL at last visit withdrew from the study after relocating.
“PRO 140 was considered generally well-tolerated as both an intravenous and subcutaneous injection,” Maddon said during his presentation at ASM Microbe 2016. “There were no drug-related [serious adverse events], and no pattern of toxicity was seen.”
In addition, Maddon said patient acceptability of PRO 140 was high.
The researchers will continue to develop PRO 140 as a standalone treatment, Maddon said, while an ongoing phase 3 trial will investigate the monoclonal antibody in combination with ART. So far, more than 200 patients have been evaluated in clinical trials of PRO 140.
“The PRO 140 study and the extension study are both ongoing,” Maddon said. “We plan to continue treating patients with PRO 140 monotherapy beyond the 120-week duration of the current study. For greater than a year — and we’re actually approaching 2 years — we believe PRO 140 subcutaneous monotherapy provided full virologic suppression, was well-tolerated and enabled the avoidance of potential toxicity of ART while preserving drug options.” – by John Schoen
Reference:
Maddon PJ, et al. Pro140 Sc monotherapy provides long-term, full virologic suppression in HIV patients. Presented at: ASM Microbe; June 16-20, 2016; Boston.
Disclosure: Maddon is a board member of Progenics Pharmaceuticals, a consultant and independent contractor for CytoDyn, and a shareholder of both companies.
Perspective
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Daniel R. Kuritzkes, MD
I think these data are really very preliminary. In my mind, they do not really tell us much about how the drug might be used. There are lots of therapies that might be used to maintain suppression once people are suppressed on a triple-drug regimen — protease monotherapy, integrase inhibitor monotherapy, etc. There may be a small number of patients who would want to get weekly injections in order to avoid having to take daily pills. However, I think that PRO 140 being limited to CCR5 virus is an another issue, and there is some concern whether people might relapse over time. It is an intriguing result, but this a small subset of a larger study, and I think we just need more data.
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