Eiger BioPharmaceuticals Announces Identification of a Novel Class of HCV Inhibitors

Publication describes key domain essential for HCV replication and basis for new small molecule inhibitors

PALO ALTO, California, January 20 - Eiger BioPharmaceuticals, Inc., a biotechnology company developing
antiviral therapies, announced today the publication of research from the
labs of Stanford scientist and Eiger Founder, Dr. Jeffrey Glenn, M.D., Ph.D.
and colleagues entitled, "Identification of a Novel Class of HCV Inhibitors".
Published in the January 20th edition of Science and Translational Medicine,
the research validates a domain, termed 4BAH2, within the non-structural
protein (NS4B) of the HCV genome, as essential for HCV replication and
describes the development of a high-throughput screen leading to the
identification of small molecule inhibitors of 4BAH2.

"The 4BAH2 is the second new domain within NS4B now proven necessary and
essential for HCV replication, and which has been shown to be susceptible to
pharmacologic inhibition. Eiger is developing small molecule inhibitors of
both NS4B-RNA binding and small molecule inhibitors of NS4B-AH2, each of
which has significant activity alone and significant synergy when combined,"
said David Cory, President and CEO of Eiger. "Inhibiting these NS4B functions
represents an exciting new approach toward developing new classes of
virus-specific agents to treat HCV."

"The discovery of a new class of HCV inhibitors against a novel target
that is described in this paper paves the way for the development of novel
anti-HCV strategies. This is of particular benefit because, like AIDS and
tuberculosis, future effective therapy for HCV is expected to require a
cocktail of several independent classes of drugs, each designed against a
different viral target. As such, the types of inhibitors described in this
paper represent ideal components of future anti-HCV drug cocktails," said
Jeffrey Glenn, M.D., Ph.D., Founder of Eiger. "I am particularly excited to
be working with the Eiger team because they have proven their ability to
rapidly develop potent derivatives of the initial compounds described in my
lab, and to efficiently move leads to the clinic."

About 4BAH2

Representing a second target of interest to Eiger within NS4B, 4BAH2 has
been genetically-validated and consists of a conserved amphipathic helix (AH)
essential for viral genome replication. 4BAH2 has a dramatic specific
biochemical activity of promoting the aggregation of lipid vesicles, with
likely relevance to the establishment of the membranous web, the site of HCV
replication. This biochemical activity was leveraged into a new high
throughput screening assay for pharmacologic inhibitors of 4BAH2 function.
Analysis of these inhibitors reveals a mechanism of action involving
inhibition of 4BAH2 induced vesicle aggregation. Eiger has developed a next
generation series of potent 4BAH2 inhibitors that are highly active as single
agents against HCV, and highly synergistic when combined with the NS4B-RNA
inhibitor, clemizole.

About Eiger BioPharmaceuticals, Inc. www.eigerbio.com

Eiger is focused on the discovery and development of new antiviral agents
against novel targets for the treatment of hepatitis virus infections.
Eiger's pipeline includes repurposed clinical stage therapeutic agents as
well as preclinical NCEs from discovery that exhibit antiviral activity
against Hepatitis C, Hepatitis D, and other viruses. Eiger investors include
InterWest Partners www.interwest.com and Vivo Ventures www.vivoventures.com.

    Contact:
    +1-650-320-9900
    info@eigerbio.com

Eiger BioPharmaceuticals, Inc., +1-650-320-9900, info at eigerbio.com