ChemoCentryx's Traficet-EN(TM) Phase II/III Induction Phase Data in Crohn's Disease...

ChemoCentryx's Traficet-EN(TM) Phase II/III Induction Phase Data in Crohn's
Disease to be Featured in Oral Presentation at 2009 Digestive Disease Week

First-in-class Oral Therapeutic for IBD with Novel Mode of Action

MOUNTAIN VIEW, Calif., May 19 /PRNewswire/ -- ChemoCentryx, Inc., today
announced that data from the company's PROTECT-1 (the Prospective Randomized
Oral Therapy Evaluation in Crohn's disease Trial) Phase II/III clinical trial
of Traficet-EN(TM) (CCX282-B) in patients with moderate-to-severe Crohn's
disease will be presented in an oral session at the upcoming 2009 Digestive
Disease Week (DDW) meeting. Traficet-EN is an orally-available small molecule
drug that controls the inappropriate immune system response underlying
inflammatory bowel diseases by blocking the CCR9 chemokine receptor.
Targeting the CCR9 chemokine receptor represents a novel approach for the
treatment of Crohn's disease and other inflammatory disorders of the
gastrointestinal system. DDW 2009 will be held on May 30 - June 4, 2009, at
McCormick Place in Chicago, Illinois.

Satish Keshav, M.D., Ph.D., Department of Gastroenterology, John Radcliffe
Hospital, Oxford University, will present Phase II/III clinical trial results
from more than 430 patients in the induction phase of the PROTECT-1 study in
the following session:

Abstract (#392): PROTECT-1 Study Demonstrated Efficacy of the
Intestine-Specific Chemokine Receptor Antagonist CCX282-B (Traficet-EN) in
Treatment of Patients with Moderate to Severe Crohn's Disease

Session/Track: IBD Controlled Clinical Trials - Immunology, Microbiology &
Inflammatory Bowel Disease
Location: McCormick Place, Room E450B
Date/Time:Monday, June 1, 2009, 3:30-3:45 PM

About CCX282-B (Traficet-EN)
Traficet-EN is an orally-available small molecule drug which is administered
in capsule form and which is believed to control the inappropriate immune
system response underlying inflammatory bowel disease (IBD) by blocking the
CCR9 chemokine receptor. In adults, CCR9 is a highly specific receptor
expressed by T cells that migrate selectively to the digestive tract. The
trafficking of T cells to the small and large intestine causes persistent
inflammation that may result in Crohn's disease or ulcerative colitis - the
two principal forms of IBD. In preclinical studies, the compound worked both
therapeutically and prophylactically in models of Crohn's disease and
ulcerative colitis. Traficet-EN may offer advantages over existing
therapeutic approaches for Crohn's disease by potentially offering convenient
once-daily oral dosing and reduced side effects. Because of its specificity,
Traficet-EN does not globally suppress the immune system.

About the PROTECT-1 Trial
PROTECT-1 is a randomized, placebo-controlled, double-blind study comprised of
three discrete phases that allow for evaluation of efficacy and safety of
Traficet-EN in inducing a clinical response or remission, as well as
maintaining response/remission in Crohn's disease over a combined total of 12
months. The innovative trial design includes a 12-week induction phase,
during which patients with moderate-to-severe Crohn's disease will receive
either Traficet-EN or placebo in order to evaluate the drug's ability to
induce a clinical response or remission. The induction phase of the study is
followed by a four-week, open label active phase, during which all subjects
receive Traficet-EN. Patients who achieve a pre-specified reduction in disease
severity are re-randomized to active drug or placebo for an additional 36-week
maintenance phase, thereby permitting an evaluation of the drug's ability to
maintain a treatment response. The primary efficacy endpoint in the induction
phase of the study is the attainment of a clinical response defined as a
decrease from baseline in the Crohn's Disease Activity Index (CDAI) score of
at least 70 points.

About ChemoCentryx
ChemoCentryx, Inc., is a clinical-stage biopharmaceutical company focused on
discovering, developing and commercializing orally-administered therapeutics
that target the chemokine and chemoattractant systems in order to treat
autoimmune diseases, inflammatory disorders and cancer. The chemokine system
is a network of secreted chemokine molecules, or ligands, and cell surface
receptors that regulates inflammation. Based on its proprietary drug discovery
and drug development platform, ChemoCentryx has internally generated multiple
clinical and preclinical-stage programs, each targeting distinct chemokine and
chemoattractant receptors with different small molecule compounds.
ChemoCentryx's lead compound, Traficet-EN, a specific CCR9 antagonist, is in a
Phase II/III multi-national clinical trial, called PROTECT-1, in patients with
moderate-to-severe Crohn's disease. CCX025, also a CCR9 antagonist, is in a
Phase I clinical trial. Additional clinical programs include the development
of CCX140, which targets the CCR2 receptor, currently in Phase I clinical
development and intended for subsequent development to treat diseases such as
Type 2 diabetes, multiple sclerosis and vascular restenosis, and CCX354, a
CCR1 antagonist in Phase I clinical testing, being developed for inflammatory
diseases such as rheumatoid arthritis. ChemoCentryx also has several programs
in preclinical development. ChemoCentryx is privately held. For more
information, please refer to www.chemocentryx.com.

Any statements in this press release about ChemoCentryx's expectations,
beliefs, plans, objectives, assumptions or future events or performance are
not historical facts and are forward-looking statements. These statements are
often, but not always, made through the use of words or phrases such as may,
believe, will, expect, anticipate, estimate, intend, predict, seek, potential,
continue, plan, should, could and would or the negative of these terms or
other comparable terminology. Forward-looking statements are not guarantees of
performance. They involve known and unknown risks, uncertainties and
assumptions that may cause actual results, levels of activity, performance or
achievements to differ materially from any results, levels of activity,
performance or achievements expressed or implied by any forward-looking
statement. Some of the risks, uncertainties and assumptions that could cause
actual results to differ materially from estimates or projections contained in
the forward-looking statements include but are not limited to (i) the
initiation, timing, progress and results of ChemoCentryx's preclinical studies
and clinical trials, (ii) ChemoCentryx's ability to advance product candidates
into clinical trials, (iii) GSK's exercise of its license options, (iv) the
commercialization of ChemoCentryx's product candidates, (v) the implementation
of ChemoCentryx's business model, strategic plans for its business, product
candidates and technology, (vi) ChemoCentryx's ability to maintain and
establish collaborations or obtain additional government grant funding, (vii)
ChemoCentryx's estimates of its expenses, future revenues, capital
requirements and its needs for additional financing, (viii) the timing or
likelihood of regulatory filings and approvals, (ix) the availability of
corporate partners, (x) the scope of protection ChemoCentryx is able to
establish and maintain for intellectual property rights covering its product
candidates and technology, (xi) the impact of competitive products and
technological changes, (xii) the availability of capital and the cost of
capital, (xiii) ChemoCentryx's financial performance, (xiv) developments
relating to ChemoCentryx's competitors and other vagaries in the biotechnology
industry and (xv) other risks.

You are cautioned not to place undue reliance on these forward-looking
statements, which speak only as of the date hereof. All forward-looking
statements are qualified in their entirety by this cautionary statement and
ChemoCentryx undertakes no obligation to revise or update this press release
to reflect events or circumstances after the date hereof. This caution is made
under the safe harbor provisions of Section 21E of the Private Securities
Litigation Reform Act of 1995.

SOURCE ChemoCentryx, Inc.

Susan M. Kanaya, SVP, Finance and Chief Financial Officer, or Markus J.
Cappel, Ph.D., Chief Business Officer, both of ChemoCentryx, Inc.,
+1-650-210-2900, investor@chemocentryx.com; or Karen L. Bergman,
+1-650-575-1509 (mobile), or Susan Pietropaolo, +1-201-923-2049 (mobile), both
of BCC Partners, for ChemoCentryx, Inc.