ChemoCentryx Reports Safety Results Available from Ongoing Phase I Trial of Orally Administered PD-L1 Inhibitor, CCX559, at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting

-- Consistent with approved antibody inhibitors of PD-L1, CCX559 demonstrates immunomodulatory activity in first cycle of treatment --

-- Safety and tolerability allow for continued dose escalation with no dose limiting toxicities to date --

SAN CARLOS, Calif., June 06, 2022 (GLOBE NEWSWIRE) -- ChemoCentryx, Inc., (Nasdaq: CCXI), today announced the presentation of safety results from the ongoing Phase I clinical study of CCX559, the Company’s highly potent, orally administered PD-L1 checkpoint inhibitor, in patients with advanced solid tumors during a poster session at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting.

In the ASCO poster titled, Results From an Ongoing Phase 1 Dose-Escalation Study of CCX559, an Orally Administered Small Molecule PD-L1 Inhibitor, in Patients With Advanced Solid Tumors (abstract #2593), ChemoCentryx reported patient baseline characteristics and safety data available from the ongoing study as of April 27, 2022, from the first 13 patients enrolled across four dose cohorts: 30 mg, 60 mg, 120 mg, and 180 mg.

The first-in-human Phase I study is assessing CCX559 in patients with a range of advanced solid tumors. Ten of the 13 patients enrolled have received at least two or more prior lines of systemic therapy. The primary objectives of the study are to evaluate the safety and tolerability, and to inform dose selection for the planned Phase Ib/II clinical trial.

To date, there have been no dose limiting toxicities (DLTs) or treatment-related serious or severe (≥ grade 3) adverse events (AEs) reported. Two patients receiving 120 mg once daily CCX559 presented with three probable immune-related AEs, which provides supportive evidence of immune activation. There have been no treatment-related AEs reported in more than one patient.

The ASCO poster also includes pharmacokinetic (PK) and pharmacodynamic (PD) data that build on the positive findings during the 2022 American Association for Cancer Research (AACR) Annual Meeting in April, providing evidence that CCX559 is pharmacologically active and 120 mg once daily is a therapeutically relevant dose. Results presented during ASCO indicate continued dose-dependent PK exposure at Day 1 for CCX559. The mean exposure at 120 mg (n=10) remains in line with preclinical projections and continues to increase at the 180 mg level (n=1). Consistent with approved antibody inhibitors of PD-L1, CCX559 demonstrates immunomodulatory activity in first cycle of treatment.

ChemoCentryx expects to present additional findings from this ongoing Phase I study at major oncology conferences through 2022. The tumor types being evaluated in the Phase I study are not known to be responsive to treatment with anti-PD-1/PD-L1 therapies, and the Company plans to advance CCX559 into a Phase Ib/II clinical trial to measure anti-tumor effects of CCX559 more directly during the second half of 2022.

About CCX559

CCX559 is a highly potent orally administered small molecule PD-L1 checkpoint inhibitor. Preclinical characterization has demonstrated that CCX559 blocks binding to PD-1 and CD80, and prevents PD-L1 inhibition of T cell activation. CCX559, when orally administered in animal models, demonstrated anti-tumor efficacy, including the ability to induce complete responses.

The PD-L1/PD-1 interaction is one of the major immune checkpoints that limits the ability of effector T cells to destroy cancer cells. As a potential next generation therapy, an orally administered small molecule inhibitor of PD-L1 could have advantageous properties compared to approved monoclonal antibodies, such as better penetration into solid tumors, reduced immunogenicity, lack of Fc-mediated side effects and convenience of oral administration.

During 2021, ChemoCentryx initiated a first-in-human Phase I dose escalation study to evaluate the safety, tolerability, PK and PD of CCX559 in patients with various types of advanced cancer. During the second half of 2022, the Company plans to advance CCX559 into a Phase Ib/II clinical trial to measure anti-tumor effects of CCX559 more directly.

About ChemoCentryx

ChemoCentryx is a biopharmaceutical company commercializing and developing new medications for inflammatory and autoimmune diseases and cancer. ChemoCentryx targets the chemokine and chemoattractant systems to discover, develop and commercialize orally administered therapies. In the United States, ChemoCentryx markets TAVNEOS^® (avacopan), the first approved orally administered inhibitor of the complement 5a receptor as an adjunctive treatment for adult patients with severe active ANCA-associated vasculitis. TAVNEOS is also in late-stage clinical development for the treatment of severe Hidradenitis Suppurativa (HS) and C3 glomerulopathy (C3G).

ChemoCentryx is also developing CCX559, a highly potent orally administered small molecule PD-L1 checkpoint inhibitor, for the treatment of patients with solid tumors. A Phase I dose escalation study for CCX559 is ongoing and ChemoCentryx plans to advance to a Phase Ib/II study in the second half of 2022. Additionally, ChemoCentryx has early-stage drug candidates that target chemoattractant receptors in other inflammatory and autoimmune diseases and in cancer. For more information about the Company visit .

TAVNEOS^® is a registered trademark of ChemoCentryx, Inc. For more information, please see the and , available at .

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," "continue" or "project" or the negative of these terms or other comparable terminology are intended to identify forward-looking statements. These statements include the Company's statements regarding the achievement of anticipated goals and milestones, whether the Company's drug candidates, including CCX559, will have better drug properties than approved medicines, such as better penetration into solid tumors, reduced immunogenicity, lack of Fc-mediated side effects and convenience of oral administration, or will be shown to be safe and effective in ongoing or future clinical trials. 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 on March 1, 2022, and its other reports which are available from the SEC's website () and on ChemoCentryx's website () 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.

Contacts

Investors:

Bill Slattery, Jr.

Vice President, Investor Relations

& Corporate Communications

650.210.2970

Media:

Stephanie Tomei

408.234.1279