Agenus Vaccine Shows Significant Reduction in Viral Burden after HerpV Generated Immune Activation
June 26 2014 - 7:00AM
Business Wire
- Phase 2 trial in patients with genital
herpes shows correlation between viral load reduction and CD8 T
cell activation, an important clinical surrogate
- Trial shows booster shot demonstrates
sustainable, long-term effect
Agenus Inc. (Nasdaq: AGEN), an immuno-oncology company
developing a portfolio of checkpoint modulators (CPMs), heat shock
protein peptide-based vaccines, and adjuvants, today announced
promising Phase 2 results for HerpV, a synthetic vaccine candidate
for the treatment of patients with genital Herpes Simplex Virus-2
(HSV-2). HerpV contains a defined mixture of peptides representing
HSV-2 antigens plus Agenus’ QS-21 Stimulon® adjuvant.
In a randomized, Phase 2, double-blind, multi-center study, the
majority of patients showed an immune response to the HSV antigens
after a series of vaccinations and a booster dose at six months.
More than half of those vaccinated developed a robust anti-HSV
cytotoxic T-cell immune response, and in those patients there was a
statistically significant 75% reduction in viral load (P<0.001;
CI: 46.2 – 88.6%). This level of reduction in viral load has the
potential to result in reduced incidence and severity of herpetic
outbreaks and a reduction in viral transmission1.
“We are pleased that the cellular immune response observed with
HerpV vaccination is associated with a significant reduction in
viral replication in the genital tract,” said Robert Stein, MD,
PhD, Chief Scientific Officer of Agenus. “The fact that our vaccine
contains multiple HSV-2 antigens may contribute to its desired
effects. We look forward to advancing discussions with potential
partners to take this program into the next phase of clinical
research.”
After the booster shot, HerpV demonstrated a durable reduction
in viral shedding approximating 14% (RR=0.86 and CIs: 0.58-1.26)
and remains consistent with the reduction in viral shedding
observed during the initial treatment period. The protocol defined
secondary analyses were viral load and viral shedding after the
booster shot, the primary endpoint of the study was reported in
November 2013.
In this study, the booster shot was given six months after the
first vaccination. Patients continue to be followed for safety and
long-term immune response. HerpV reported adverse events have
mostly been in line with expectations for a therapeutic vaccine and
with effects commonly associated with QS-21 Stimulon® adjuvant.
These adverse events are short-lived and include flu-like symptoms
and injection-site reactions.
About the Phase 2 HerpV Study
In November 2013, Agenus announced the trial met its primary
endpoint showing a statistically significant reduction in viral
shedding. A total of 80 subjects with a history of 1-9 herpes
recurrences within the prior 12 months were randomized into the
trial and 70 subjects received the active treatment, HerpV and
QS-21 Stimulon, and 10 subjects received placebo. Three injections
of HerpV at a dose of 240 µg (includes12 µg of a mix of 32
different HSV-2 antigenic peptides) or placebo were given at two
week intervals. HSV-2 activity in the genito-urinary tract was
monitored by PCR for HSV-2 DNA in genital swabs for 45 days before
and after the initial course of three vaccinations.
The primary analysis, which looked at viral shedding after the
initial three HerpV vaccinations, demonstrated that subjects who
received HerpV had a statistically significant reduction in viral
shedding (P=0.015; RR=0.85). These results suggest a 15% reduction
in viral shedding after the initial treatment period before the
administration of the booster injection. The results also
demonstrate a reduction in viral load of 34% (P=0.08). Placebo
patients showed no reduction compared to baseline in either
parameter. Notably, patients were not on any anti-viral treatments
during their swabbing period.
About Agenus’ Heat Shock Protein Platform (HSP) and
Recombinant Series HerpV
HerpV is a recombinant therapeutic vaccine for genital herpes
caused by the herpes simplex virus-2 (HSV-2). The vaccine is based
on Agenus' HSP platform technology, and contains Agenus’
proprietary QS-21 Stimulon, a plant-derived adjuvant that boosts
specific immune responses. HerpV consists of recombinant human heat
shock protein-70 complexed with 32 distinct 35-mer synthetic
peptides from the HSV-2 proteome. This broad spectrum of herpes
antigens is intended to allow for more accurate immune targeting
and surveillance, reducing the likelihood of immune escape.
Further, the diversity of antigens in HerpV increases the chance of
providing efficacy for a wide segment of the patient
population.
About HSV-2
About one in six Americans (16.2 percent) between the ages of 14
and 49 is infected with herpes simplex virus type 2 (HSV-2),
according to the Centers for Disease Control and Prevention
(http://www.cdc.gov/std/Herpes/STDFact-Herpes.htm). Herpes is the
fastest growing STD in America, and experts predict that one in
four Americans will contract an STD sometime in their life. Since
two thirds of the population that gets herpes is age 25 or younger,
it is a real health threat to society. HSV-2 is a lifelong and
incurable infection that can cause recurrent and painful genital
sores.
About Agenus
Agenus is an immuno-oncology company developing a portfolio of
checkpoint modulators (CPMs), heat shock protein peptide vaccines
and adjuvants. Agenus’ checkpoint modulator programs target GITR,
OX40, CTLA-4, LAG-3, TIM-3 and PD-1. The company’s proprietary
discovery engine Retrocyte Display® is used to generate fully human
therapeutic antibody drug candidates. The Retrocyte Display
platform uses a high-throughput approach incorporating IgG format
human antibody libraries expressed in mammalian B-lineage cells.
Agenus’ heat shock protein vaccines for cancer and infectious
disease are in Phase 2 studies. The company’s QS-21 Stimulon®
adjuvant platform is extensively partnered with GlaxoSmithKline and
Janssen and includes several candidates in Phase 3 trials. For more
information, please visit www.agenusbio.com, or connect with the
company on Facebook, LinkedIn, Twitter and Google+. For more
information, please visit www.agenusbio.com.
Forward-Looking Statement
This press release contains forward-looking statements,
including statements regarding clinical trial activities and
results and the potential application of the Company’s technologies
and product candidates in the prevention and treatment of diseases.
These forward-looking statements are subject to risks and
uncertainties that could cause actual results to differ materially.
These risks and uncertainties include, among others, the factors
described under the Risk Factors section of our Quarterly Report on
Form 10-Q filed with the Securities and Exchange Commission for the
period ended March 31, 2014. Agenus cautions investors not to place
considerable reliance on the forward-looking statements contained
in this release. These statements speak only as of the date of this
document, and Agenus undertakes no obligation to update or revise
the statements. All forward-looking statements are expressly
qualified in their entirety by this cautionary statement. Agenus’
business is subject to substantial risks and uncertainties,
including those identified above. When evaluating Agenus’ business
and securities, investors should give careful consideration to
these risks and uncertainties.
Stimulon and Retrocyte Display are registered trademarks of
Agenus Inc. and its subsidiaries.
1 Schiffer JT, et.al. J. R. Soc. Interface 11: 2014.
Media and Investor Contact:Agenus Inc.Jonae R. Barnes,
617-818-2985Vice PresidentInvestor Relations andCorporate
Communicationsjonae.barnes@agenusbio.com
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