(CCXI) Positive Results From ChemoCentryx Phase II Diabetic Nephropathy Trial

— Significant reduction in proteinuria over 52 weeks of treatment suggests CCX140 may have renoprotective effects exceeding current standard of care alone —

— Separately, poster describing anti-thrombogenic potential of complement C5a receptor inhibitor CCX168 in serum from patients with atypical hemolytic uremic syndrome (aHUS) to be presented —

MOUNTAIN VIEW, Calif., May 28, 2015  — ChemoCentryx, Inc., (Nasdaq:CCXI), a clinical-stage biopharmaceutical company focused on autoimmune diseases, inflammatory disorders and cancer, today announced data presentations from two of its chemoattractant receptor programs, CCR2 and C5aR, at the 52^nd European Renal Association – European Dialysis and Transplant Association (ERA-EDTA) Congress being held May 28 to 31 in London, UK.

Today, in a Late Breaking Clinical Trial presentation, positive 52-week data from the Company’s Phase II clinical trial in patients with diabetic nephropathy with CCX140, an inhibitor of the chemokine receptor known as CCR2, were presented by Professor Dick de Zeeuw, M.D., Ph.D., Chair of the Research Section of the Department of Clinical Pharmacy and Pharmacology at the University Medical Center in Groningen, The Netherlands. Professor de Zeeuw’s oral presentation focused on the CCX140 Phase II study and its primary endpoint.

“We are pleased to have such an esteemed nephrologist as Professor de Zeeuw present his analyses of the results from our Phase II study in patients with diabetic nephropathy. The focus of his presentation on the treatment effect of CCR2 inhibition on reducing levels of albuminuria, the study’s primary endpoint, is particularly relevant given Professor de Zeeuw’s expertise and understanding of proteinuria and its effect on renal function,” said Thomas J. Schall, Ph.D., President and Chief Executive Officer, ChemoCentryx. “We look forward to presenting additional CCX140 Phase II data, including important pre-specified subgroup analyses at future medical meetings.”

As previously announced, top line data from the CCX140 Phase II trial in patients with diabetic nephropathy included the following results:

• The trial met its primary endpoint by demonstrating that treatment with 5 mg of CCX140 given orally once daily added to a standard of care regimen (SOC) of angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor II blocker (ARB) treatment resulted in a statistically significant (p=0.0148) reduction in urinary albumin:creatinine ratio (UACR), beyond that achieved with SOC alone;
• The maximum treatment effect was reached at 12 weeks; in patients who received 5 mg CCX140 continuously for 52 weeks, a sustained reduction in albuminuria induced by CCX140 relative to SOC alone was observed over the full year;
• Treatment with CCX140 showed improvements in the profile of the estimated glomerular filtration rate (eGFR), represented by an attenuation in the slope of annual decline in eGFR. The treatment group receiving 5 mg of CCX140 in addition to SOC showed an attenuated annual slope decline of 1.9 mL/min/1.73 m², compared to SOC alone group, 3.4 mL/min/1.73 m². These results represent a 44 percent annualized improvement in eGFR over SOC alone;
• In a pre-specified sub-population in the study, patients who were highly proteinuric (baseline albuminuria levels of 800mg/g creatinine and above), a 66 percent annualized relative improvement in eGFR slope over SOC alone was observed;
• CCX140 appeared to be well tolerated with a low overall dropout rate over the 52-week treatment period.

Regarding another chemoattractant receptor inhibitor program at the Company, ChemoCentryx scientists and their collaborators will outline research in atypical Hemolytic Uremic Syndrome (aHUS) and the ability of CCX168, a C5aR inhibitor, to significantly reduce the formation of platelet micro-thrombi on an ex-vivo assay system of endothelial cells. These data will be presented in a poster session on Saturday, May 30^th. The inhibition of micro-thrombi was dose-dependent on CCX168 and, in side-by-side experiments, the anti-thrombotic effect of CCX168 was comparable to that of eculizumab, which is the first agent approved for aHUS. The Company is initiating a CCX168 Phase IIa proof-of-concept study in aHUS patients with end stage renal disease.

About the CCX140 Study

The objectives of the Phase II study, which took place at multiple sites across six European countries, were to determine the safety, tolerability and signs of clinical effect of CCX140 in patients with diabetic nephropathy. CCX140 was studied in a randomized, double-blind, placebo controlled clinical trial in 332 patients with residual albuminuria, despite having received an ACE inhibitor or ARB for at least eight weeks prior to screening for this trial. The original protocol had a 12-week treatment period that was extended to 52 weeks by protocol amendment. Of the 332 patients enrolled in the study initially, 102 patients were ineligible to re-enroll after the protocol amendment approval due to the length of time off treatment. As such 196 patients participated in the study extension to receive treatment for 52 weeks. The primary safety objective was evaluation of the safety profile of CCX140 based on the incidence of adverse events. The primary efficacy endpoint was the evaluation of the effect of CCX140 treatment over 52 weeks on first morning urinary albumin:creatinine ratio. Secondary objectives included evaluation of the effect of CCX140 on eGFR and HbA1c. At baseline, the mean age of the study population was 63 years, the median duration of type 2 diabetes was 14.5 years and the median duration of nephropathy was 3.3 years. The baseline mean urinary ACR for the population overall was 636 mg/g creatinine and baseline mean eGFR was 63 mL/min/1.73 m². Baseline mean arterial blood pressure was 98 mm Hg.

About CCX140

CCX140 targets the chemokine receptor known as CCR2 and is being developed as an orally administered therapy for the treatment of diabetic nephropathy, or diabetic kidney disease. CCR2 is found on subsets of monocytes and macrophages, which are cells of the immune system believed to play an important role in inflammatory processes. Blocking CCR2 is intended to reduce the abnormal monocyte- and macrophage-driven inflammatory response implicated in renal diseases such as diabetic nephropathy. CCR2 may also have a direct role in the function of other specialized cells in the kidney, where its inhibition would correlate with a positive therapeutic effect. CCX140 has successfully completed a Phase II clinical trial where it was shown to be safe and well tolerated while demonstrating statistically significant improvements in kidney function in patients with diabetic nephropathy.

About CCX168

CCX168, a C5aR inhibitor, targets the chemoattractant receptor known as C5aR (which binds to the complement fragment C5a). ChemoCentryx is developing CCX168 for various autoimmune disorders including anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV), Immunoglobulin A nephropathy (IgAN) and atypical Hemolytic Uremic Syndrome (aHUS). CCX168 appears to be safe, well tolerated and successful in allowing both reduction and elimination of high-dose corticosteroids, part of standard of care for AAV patients, without compromising efficacy or safety during a 12-week treatment period.

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 biological network that regulates inflammation via a collection of secreted chemokine molecules, or ligands, and their specific cell surface receptors. Based on its proprietary drug discovery and drug development platform, ChemoCentryx has generated multiple clinical and preclinical-stage programs, each targeting distinct chemokine and chemoattractant receptors with different small molecule compounds. CCX140, a CCR2 inhibitor, successfully completed a Phase II clinical trial where it was shown to be safe and well tolerated while demonstrating statistically significant improvements in kidney function in patients with diabetic nephropathy. CCX168, a C5aR inhibitor, is in Phase II development for the treatment of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). CCX168 appears to be safe, well tolerated and successful in allowing both reduction and elimination of high-dose corticosteroids, part of standard of care for AAV patients, without compromising efficacy or safety during a 12-week treatment period. CCX872, a second CCR2 inhibitor, successfully completed Phase I development and is in development for the treatment of non-resectable pancreatic cancer. Vercirnon (also known as Traficet-EN or CCX282) is a specific CCR9 inhibitor for the treatment of inflammatory bowel disease. Other clinical programs include CCX507, a next generation CCR9 inhibitor, which has successfully completed Phase I development and CCX354, a CCR1 inhibitor which successfully completed a Phase II clinical trial for the treatment of rheumatoid arthritis. ChemoCentryx also has several programs in advanced preclinical development.

Forward-Looking Statements

ChemoCentryx cautions that statements included in this press release that are not a description of historical facts are forward-looking statements. Words such as “may,” “could,” “will,” “would,” “should,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “intend,” “predict,” “seek,” “contemplate,” “potential” or “continue” or the negative of these terms or other comparable terminology are intended to identify forward-looking statements. These statements include statements regarding whether CCX140 will be shown to be effective in Phase III clinical trials in the treatment of diabetic nephropathy or whether CCX168 will be effective in the treatment of atypical hemolytic uremic syndrome. The inclusion of forward-looking statements should not be regarded as a representation by ChemoCentryx that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risks and uncertainties inherent in the ChemoCentryx business and other risks described in the Company’s filings with the Securities and Exchange Commission (“SEC”). Investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and ChemoCentryx undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof. Further information regarding these and other risks is included under the heading “Risk Factors” in ChemoCentryx’s periodic reports filed with the SEC, including ChemoCentryx’s Annual Report on Form 10-K filed with the SEC March 13, 2015 and its other reports which are available from the SEC’s website (www.sec.gov) and on ChemoCentryx’s website (www.chemocentryx.com) under the heading “Investors.” All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995.

Source: ChemoCentryx (CCXI-G)

CONTACT: Susan M. Kanaya
         Senior Vice President, Finance and
         Chief Financial Officer or
         Markus J. Cappel, Ph.D.
         Chief Business Officer
         650.210.2900
         investor@chemocentryx.com

         Media:
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         Investors:
         Kimberly Minarovich
         Burns McClellan
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