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UPDATE: Gilead Reports Preclinical Data

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Gilead Sciences, Inc. (NASDAQ: GILD) today announced results from a preclinical
study conducted in collaboration with researchers at Beth Israel Deaconess
Medical Center evaluating a proprietary investigational oral toll-like
receptor 7 (TLR7) agonist and analogue of GS-9620 as part of an HIV
eradication strategy. Data demonstrate that treatment with the TLR7 agonist
induced transient plasma Simian Immunodeficiency Virus (SIV) RNA, as well as
reduced SIV DNA in virally suppressed rhesus macaques given antiretroviral
therapy (ART). In addition, the study found that after discontinuation of ART,
SIV viral loads were lower among macaques that received the proprietary TLR7
agonist compared to the placebo group. These data were presented in an oral
session (Session O-9) at the 22^nd Conference on Retroviruses and
Opportunistic Infections (CROI) in Seattle.

"One reason current therapies can't cure HIV is that latent reservoirs of the
virus persist even among individuals who are virally suppressed on ART," said
James Whitney, PhD, Assistant Professor of Medicine, Harvard Medical School,
and study Principal Investigator in the Center for Virology and Vaccine
Research at Beth Israel Deaconess Medical Center in Boston. Dr. Whitney is
also an Associate Member of The Ragon Institute of MGH, MIT and Harvard, which
was founded in 2009 to contribute to the accelerated discovery of an HIV/AIDS
vaccine and to establish itself as a world leader in the collaborative study
of immunology. "These data demonstrate that, given alongside ART, the TLR7
agonist may have the potential to both stimulate virus production and
eliminate latently infected cells – an eradication strategy being explored

In this placebo-controlled study, 10 SIV-infected rhesus macaques received ART
for 38 weeks, at which point they were virally suppressed (plasma RNA less
than 50 copies/mL). At week 38, six macaques were given placebo and four
macaques were given seven bi-weekly doses of the TLR7 agonist, while
maintaining ART. Total viral DNA levels were measured at baseline and two
weeks after completion of the TLR7 agonist dosing in peripheral blood
mononuclear cells (PBMC), colon and inguinal lymph nodes – where latent SIV
reservoirs are common. ART was discontinued two weeks after the final dose of
the TLR7 agonist to assess plasma viral rebound.

The four macaques receiving bi-weekly doses of the TLR7 agonist were given 0.1
mg/kg for the first dose, 0.2 mg/kg for the second dose and 0.3 mg/kg for each
of the last five doses. Doses 1-3 had no effect on plasma viremia, whereas
doses 4-7 led to transient and consistent increases in plasma virus (500-1,000
SIV RNA copies/mL) in all four macaques with a return to less than 50
copies/mL within four to seven days after receiving the TLR7 agonist. In
addition, SIV DNA levels of the four treated macaques were reduced by 30 to 90
percent compared to the placebo group, which remained unchanged. Following
discontinuation of ART in the macaques that received the TLR7 agonist, plasma
SIV RNA was ~0.5 log[10] lower compared to the placebo group.

"These preliminary results suggest that TLR7 agonists may have a role to play
in HIV eradication strategies," said Norbert W. Bischofberger, PhD, Gilead's
Executive Vice President, Research and Development and Chief Scientific
Officer. "GS-9620 is a potent TLR7 agonist currently being evaluated in a
Phase 2 study in patients with chronic hepatitis B for its potential to reduce
HbSAg. Based on today's results, we are now also looking forward to moving
GS-9620 into proof-of-concept studies in HIV-infected individuals taking ART."

The proprietary TLR7 agonist compound and GS-9620 are investigational agents
and their safety and efficacy have not been established.

Posted-In: News FDA Press Releases


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