Gilead Announces Data from New Preclinical Study Evaluating a Combination of an Investigational TLR7 Agonist and an Investigational HIV Envelope Targeting Antibody in SHIV-Infected, Virally Suppressed Monkeys
“HIV has the ability to hide in certain immune cells, which is called the latent viral reservoir and which represents a key barrier to curing HIV. New HIV therapies that aim to wake up and target the viral reservoir have the potential to play an important role in long-term viral suppression without ART,” said Dan H. Barouch, MD, PhD, Professor of Medicine, Harvard Medical School, and Director, Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center. Dr. Barouch, who led the study, is also a member of the Ragon Institute of MGH, MIT and Harvard. “In this proof-of-concept preclinical study, 45 percent of the animals that received both GS-9620 and PGT121 did not demonstrate viral rebound after stopping ART, suggesting that this combination may be able to target the viral reservoir in virally suppressed monkeys.”
In the study, 44 SHIV-infected rhesus monkeys started ART on day 7 post-infection. After 96 weeks of continuous ART, the animals were divided into four equal groups that received either 5 doses of PGT121 (10 mg/kg infusion every two weeks for 10 weeks) (n=11), 10 doses of GS-9620 (0.15 mg/kg by oral gavage every two weeks for 20 weeks) (n=11), both PGT121 and GS-9620 (n=11), or neither (placebo) (n=11). Animals continued to receive ART throughout this period and for 16 weeks afterwards. ART was discontinued at week 130 and viral rebound was monitored in plasma.
After ART discontinuation, 11 of 11 animals in the placebo arm experienced viral rebound with a median rebound time of 21 days, nine of 11 animals that received only PGT121 demonstrated viral rebound and 10 of 11 animals that received only GS-9620 showed viral rebound. In contrast, five of 11 animals that received the combination of PGT121 and GS-9620 demonstrated no viral rebound for at least 168 days, and the other six animals in the combination group rebounded but then began re-suppressing the virus without ART.
“We remain committed to researching and developing HIV eradication strategies, and we are encouraged by these data presented at CROI from a preclinical animal model of HIV infection showing that the combination of GS-9620 and PGT121 may potentially induce viral remission in the absence of ART,” said Norbert W. Bishofberger, PhD, Gilead’s Executive Vice President, Research and Development and Chief Scientific Officer. “GS-9620 is currently in a Phase 1b dose-escalation study in ART-suppressed people living with HIV and we have advanced GS-9722, a derivative of PGT121, into Phase 1 testing.”
The proprietary bNAbs PGT121 and GS-9722, as well as the TLR7 agonist GS-9620, are investigational agents and their safety and efficacy have not been established. There is no cure for HIV or AIDS.
This research was supported by the Bill & Melinda Gates Foundation and the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.