Avila Presents Preclinical Data on its Novel, Orally-Available, Pan-Genotype Protease Inhibitor, AVL-181, Demonstrating Protein Silencing of Hepatitis C Virus

In Vivo Data Demonstrates Covalent Modification Achieved for Prolonged Duration
of Action
NICE, France & WALTHAM, Mass.--(Business Wire)--
Avila Therapeutics, Inc., a biotechnology company developing novel covalent
drugs that treat diseases through protein silencing, presented results of
preclinical studies on its highly selective, pan-genotype, small molecule
Hepatitis C Virus (HCV) protease inhibitor, AVL-181. The data showed that
AVL-181 bonds selectively, covalently and irreversibly to HCV protease (also
known as "NS3/4A"), thus silencing a key protein necessary for successful viral
replication resulting in a prolonged duration of action.

Furthermore, the data demonstrate that the amount of HCV protease silenced by
AVL-181 can be measured in a dose- and time-dependent manner in an animal model
using Avila`s novel translational technology known as a covalent probe. With
this novel technology, Avila demonstrated that AVL-181 successfully blocked HCV
protease enzyme activity and that the HCV protease target was covalently bonded
and silenced in vivo. These data were presented today at the 16th International
Symposium on HCV and Related Viruses in Nice, France.

"In addition to the ability of AVL-181 to provide sustained inhibition across
multiple genotypes and drug-resistant mutations of the HCV protease, these data
now demonstrate a unique translational advantage. With Avila`s covalent probe
technology, efficacy and target occupancy can be directly correlated and
measured, which is a powerful tool for drug development," said Katrine Bosley,
Chief Executive Officer, Avila. "These data provide further support for the
clinical evaluation of AVL-181, and we are planning to advance into clinical
development next year."

In the study, "Protein Silencing of Hepatitis C Virus NS3/4A Protease In Vitro
and In Vivo Using a Novel Drug Design Strategy" (Poster P203), the data
demonstrate that the orally available, novel HCV protease inhibitor, AVL-181:

* Potently and irreversibly silences wild-type and drug-resistant HCV proteases;

* Durably inhibited the HCV protease, including drug resistant mutants, for more
than 24 hours after a single exposure as measured in a novel in vivo model in
which NS3/4A is expressed and active in the mouse liver; this prolonged
inhibition correlates with the protease half-life and contrasts with the need
for nearly continuous exposure required by the reversible HCV protease
inhibitors currently in late-stage clinical trials;
* Occupies the HCV protease target for several hours after the drug had been
cleared, as measured with a novel covalent probe technology; this protease
occupancy correlated directly with sustained inhibition of the protease, and the
return of protease activity was correlated with new synthesis of NS3 protease;
and
* Has excellent pharmacokinetic properties, including excellent oral
bioavailability in rats as measured in both plasma and liver.

About the Avilomics Platform and Covalent Drugs

The Avilomics platform is Avila`s powerful approach to design and develop
covalent drugs that strongly, selectively, and resiliently bond to
disease-causing proteins, thereby silencing their activity and producing
superior pharmacological outcomes. The approach with covalent drugs inherently
provides prolonged duration of action through this silencing of the disease
target. Covalent drugs can also solve the critical therapeutic challenges of
drugging difficult targets and addressing resistance mutations. The three
components of Avilomics are:

* Compositions: Innovative chemical structures for forming highly selective, not
indiscriminate, covalent bonds
* Design: Proprietary informatics to uniquely identify sites amenable to
selective covalent modification and target silencing
* Testing: Empirical methods to demonstrate covalent specificity at both target
and proteomic levels

Together, these components provide a platform for efficient design and testing
of covalent drugs. Avilomics opens up the broad potential of covalent drugs
across target classes and disease areas, as demonstrated with the company`s
emerging pipeline of novel, protein-silencing covalent drugs.

About Avila Therapeutics, Inc.

Avila focuses on design and development of covalent drugs to achieve
best-in-class outcomes that cannot be achieved through traditional chemistries.
This approach is called "protein silencing". The company is developing a
pipeline of novel, protein-silencing covalent drugs with a current focus on
viral infection, cancer and autoimmune disease. Avila is funded by leading
venture capital firms: Abingworth, Advent Venture Partners, Atlas Ventures,
Novartis Option Fund, and Polaris Venture Partners. For additional information,
please visit http://www.avilatx.com.

Yates Public Relations
Adriana Jenkins, 617-710-8350

Copyright Business Wire 2009