Last updated on April 18, 2014 at 16:58 EDT

Virobay and LEO Pharma Initiate a Phase 1 Trial of VBY-891, a Compound Intended for Oral Treatment of Psoriasis

March 18, 2013

MENLO PARK, California and BALLERUP, Denmark, March 18, 2013 /PRNewswire/ –

Virobay, Inc. and LEO Pharma A/S today announced that their collaboration on the
development of an oral treatment for psoriasis has reached an important milestone as
Virobay has now initiated a Phase 1 clinical trial of VBY-891 – a selective cathepsin S

http://photos.prnewswire.com/prnh/20130221/595427 )

The first Phase 1 trial of VBY-891 is a double-blind, randomized, placebo-controlled
study designed to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics
of single and multiple escalating doses of VBY-891 in healthy adults.

“The initiation of this Phase 1 trial represents a significant development objective
for Virobay’s collaboration with LEO Pharma,” stated Robert Booth, Ph.D., Chief Executive
Officer of Virobay. “Virobay has plans to initiate clinical studies with additional
cathepsin inhibitors during 2013 as we seek to develop new therapies for underserved
diseases. Published prelinical data suggest that cathepsin S inhibition may provide a
therapeutic benefit in patients with dermatological disorders such as psoriasis. In
addition, our own preclinical data with selective cathepsin S inhibitors has demonstrated
efficacy in models of both psoriasis and atopic dermatitis,” stated Robert Booth. “We look
forward to assessing the data from these Phase 1 trials, which will incorporate the
evaluation of several biomarkers, to guide our Phase 2 clinical development plans for

“Reaching this important milestone in our collaboration with Virobay brings us one
step closer to provide an oral treatment for psoriasis patients. We believe that VBY-891
has the potential to provide an oral treatment that may alleviate symptoms of psoriasis.
LEO Pharma strives to constantly expand and improve treatment options for patients and
this is an important example of our commitment to meeting patient needs. To the best of
our knowledge, the VBY-891 compound has the potential to be the first in class on the
market,” said Kim Kjoller, Senior Vice President, Global Development, LEO Pharma.


About Cathepsin S and VBY-891

Cathepsin S is a member of the cysteine protease family of cathepsin inhibitors that
catalyzes the final proteolytic step in the processing of invariant chain in specific
antigen presenting cells. This step is essential in the maturation and loading of MHC
Class II with antigenic peptides and subsequent activation of CD4+ T cells. Continuous
presentation of antigenic self-peptides is thought to be involved in the maintenance of
chronic disease in autoimmune disorders, including psoriasis. Inhibition of cathepsin S is
likely to result in a reduction in antigen presentation without an impact on innate

VBY-891 is a next generation cathepsin S inhibitor that is a potent, competitive and
reversible inhibitor of purified cathepsin S. It has picomolar inhibitory potency against
the cathepsin S enzyme and nanomolar inhibitory potency in cellular assays. VBY-891 is
also highly selective against human cathepsins L, B, F and K. Sustained cathepsin S
inhibition after oral dosing has been demonstrated in vivo through the use of a biomarker.
VBY-891 shows potent inhibitory activity in models of autoimmunity and neuropathic pain.
Therefore, inhibition of cathepsin S may have therapeutic potential across a range of
dermatological conditions.

About the collaboration

The multi-million dollar collaboration between Virobay Inc. and LEO Pharma A/S was
entered in 2012 when LEO Pharma in-licensed the promising compound from Virobay. The
collaboration agreement involves up-front payment to Virobay of USD 7m, followed by
milestone payments totalling up to USD 300m and tiered to royalties. The compound has been
tested in pre-clinical studies and the project is now entering the next phase – a phase 1
clinical trial in healthy human volunteers. After this trial has been completed, the plan
is to do testing on psoriasis patients later this year. If the process proceeds as
planned, the collaboration may result in an oral treatment for psoriasis in 6-7 years.

About Virobay, Inc.

Founded in 2006, Virobay is a leader in the design, synthesis and development of small
molecule inhibitors of cysteine proteases, a class of enzymes that are key mediators in a
variety of diseases, including autoimmunity, neuropathic pain, liver disease, cancer and
cardiovascular disorders. Virobay’s clinical pipeline currently includes product
candidates in autoimmune disease, neuropathic pain and liver fibrosis. For more
information, please visit http://www.virobayinc.com

About LEO Pharma

LEO Pharma helps people achieve healthy skin. By offering care solutions to patients
in more than 100 countries globally, LEO Pharma supports people in managing their skin
conditions. Founded in 1908 and owned by the LEO Foundation, the healthcare company has
devoted decades of research and development to delivering products and solutions to people
with skin conditions. LEO Pharma is headquartered in Denmark and employs approximately
5,000 people worldwide.

For more information, visit http://www.leo-pharma.com.



SOURCE Virobay, Inc. and LEO Pharma A/S

Source: PR Newswire