CStone Pharmaceuticals and Blueprint Medicines Initiate Phase 1b/2 Clinical Trial of Fisogatinib in Combination with CS1001 for Patients with Hepatocellular Carcinoma

SUZHOU, China and CAMBRIDGE, Mass., Jan. 6, 2020 /PRNewswire/ -- CStone Pharmaceuticals ("CStone", HKEX: 2616), a biopharmaceutical company focused on developing and commercializing immuno-oncology and precision medicines, and Blueprint Medicines Corporation (NASDAQ: BPMC), a precision therapy company focused on genomically defined cancers, rare diseases and cancer immunotherapy, today announced the dosing of the first patient in a Phase 1b/2 trial evaluating fisogatinib in combination with CS1001 for the treatment of locally advanced or metastatic hepatocellular carcinoma (HCC). The study will be conducted across multiple clinical sites in China, where according to GLOBOCAN data, nearly half of the world's new HCC cases occurred in 2018.

This trial will assess the potential for two complementary treatment approaches – precision therapy and immuno-oncology therapy – to enhance anti-tumor activity in locally advanced or metastatic HCC. Discovered by Blueprint Medicines, fisogatinib is an investigational, potent and highly selective inhibitor of fibroblast growth factor receptor 4 (FGFR4) in clinical development for the treatment of advanced FGFR4-driven HCC. CS1001 is an investigational anti-PD-L1 monoclonal antibody being developed by CStone for multiple tumor types. Preclinical studies in an HCC model have shown that treatment with fisogatinib stimulated T-cell infiltration into the tumor microenvironment, suggesting that combining fisogatinib with a PD-L1 inhibitor may enhance anti-tumor activity in patients with FGFR4-driven HCC.

Blueprint Medicines and CStone Pharmaceuticals have an exclusive collaboration and license agreement for the development and commercialization of fisogatinib and certain other drug candidates in Mainland China, Hong Kong, Macau and Taiwan. Blueprint Medicines retains development and commercial rights for these drug candidates in the rest of the world.

"The CStone collaboration has rapidly expanded our global development activities into the Asia-Pacific region, where our partner has deep experience working with leading academic centers and local regulatory authorities," said Andy Boral, M.D., Ph.D., Chief Medical Officer at Blueprint Medicines. "We look forward to advancing our fisogatinib clinical program by conducting a Phase 1b/2 trial in China, where the incidence of HCC is disproportionately high. Because fisogatinib has exquisite selectivity against an oncogenic driver, we believe this investigational treatment is well-positioned for combination therapy. Fisogatinib and CStone's PD-L1 inhibitor CS1001 have complementary mechanisms of action that may offer durable clinical activity in patients with HCC."

"HCC is a particularly aggressive disease and China is currently faced with enormous challenges due to limited effective treatment options and poor prognosis in HCC patients at advanced stages," said Archie Tse, M.D., Ph.D., Chief Translational Medicine Officer at CStone. "CStone is committed to addressing unmet clinical needs through identifying potentially transformative combination regimens against complex cancers like HCC. We are pleased that through our dedicated efforts, we have successfully achieved the dosing of the first patient in the Phase 1b/2 trial of fisogatinib in combination with CS1001, which hopefully will bring meaningful clinical benefits to advanced HCC patients. CS1001 is one of CStone's backbone immuno-oncology assets and multiple combination therapy trials with CS1001 have been carried out."

Data from Blueprint Medicines' ongoing Phase 1 trial, which was published online in Cancer Discovery on October 1, 2019, showed that fisogatinib monotherapy was clinically active and well-tolerated in patients with heavily pretreated advanced HCC. These results support fisogatinib's potential as the first molecular biomarker-driven targeted therapy in HCC.

A Phase 1 dose-escalation study of CS1001 has been completed in China. Phase 1 data published at the 22^nd Annual Meeting of the Chinese Society of Clinical Oncology (CSCO 2019) has demonstrated sustained clinical benefits from CS1001 in multiple tumor types, including gastric cancer, esophageal cancer and microsatellite instability high/deficient mismatch repair (MSI-H/dMMR) solid tumors. Pooled safety data from the Phase 1b trial released at the European Society of Medical Oncology 2019 Congress (ESMO 2019) showed that CS1001 had a promising safety and tolerability profile. These data indicate CS1001's therapeutic potential in multiple tumor types including HCC.

About HCC

Liver cancer is the second leading cause of cancer-related deaths worldwide, with HCC accounting for most liver cancers. The highest incidence of HCC occurs in regions with endemic hepatitis B virus, including Southeast Asia and sub-Saharan Africa. Nearly half of the world's new HCC cases are diagnosed in China. Treatment options for patients with advanced HCC are limited, with currently approved therapies providing time to progression of three to seven months and an overall survival of nine to 13 months. FGF19 is the ligand that activates FGFR4, a receptor that promotes hepatocyte proliferation and regulates bile acid homeostasis in the liver. Blueprint Medicines estimates that approximately 30 percent of patients with HCC have tumors with aberrantly activated FGFR4 signaling.

About the Phase 1b/2 Clinical Trial of Fisogatinib in Combination with CS1001

The Phase 1b/2 clinical trial is an open-label study of fisogatinib in combination with CS1001 for the treatment of patients with locally advanced or metastatic HCC. The trial consists of two parts: a dose-escalation phase and a dose-expansion phase. The dose-escalation phase was designed to evaluate two doses of fisogatinib in combination with a fixed dose of CS1001. The objective of the dose-escalation phase is to identify the recommended Phase 2 dose that will be used in the dose-expansion phase.

Objectives of the trial include evaluating the safety, tolerability, pharmacokinetics and anti-tumor activity of the combination regimen. FGF19 expression will be determined at a central laboratory. The trial is designed to enroll approximately 50 patients across multiple sites in China. For additional information on the trial, please go to clinicaltrials.gov.

About Fisogatinib

Fisogatinib is an orally available, potent, irreversible inhibitor of FGFR4. Fisogatinib was specifically designed by Blueprint Medicines to inhibit FGFR4 with exquisite selectivity, thereby sparing the paralogs FGFR1, FGFR2 and FGFR3. Preclinical data has validated FGFR4 as an oncogenic driver for a subset of patients with advanced HCC.

Blueprint Medicines is developing fisogatinib, an investigational medicine, for the treatment of patients with FGFR4-activated HCC. The U.S. Food and Drug Administration has granted orphan drug designation to fisogatinib for the treatment of HCC.

About CS1001

CS1001 is an investigational monoclonal antibody directed against PD-L1 being developed by CStone. Authorized by the U.S. based Ligand Corporation, CS1001 is developed by the OMT transgenic animal platform, which can generate fully human antibodies in one step. As a fully human, full-length anti-PD-L1 monoclonal antibody, CS1001 mirrors natural G-type immune globulin 4 (IgG4) human antibody, which can reduce the risk of immunogenicity and potential toxicities in patients, potentially representing a unique advantage over similar drugs.

CS1001 has completed a Phase 1 dose-escalation study in China, in which the drug showed good tolerability. During Phase 1a and 1b stages of the study, CS1001 produced sustained clinical benefits in multiple tumor types.

CS1001 is being investigated in a number of ongoing clinical trials, including one Phase 1 bridging study in the U.S. In China, its clinical program includes one multi-arm Phase 1b study, two pivotal Phase 2 studies, and four Phase 3 studies for several tumor types.

About Blueprint Medicines

Blueprint Medicines is a precision therapy company striving to improve human health. With a focus on genomically defined cancers, rare diseases and cancer immunotherapy, we are developing transformational medicines rooted in our leading expertise in protein kinases, which are proven drivers of disease. Our uniquely targeted, scalable approach empowers the rapid design and development of new treatments and increases the likelihood of clinical success. We are currently advancing three investigational medicines in clinical development, along with multiple research programs. For more information, visit www.BlueprintMedicines.com and follow us on Twitter (@BlueprintMeds) and LinkedIn.

About CStone

CStone Pharmaceuticals (HKEX: 2616) is a biopharmaceutical company focused on developing and commercializing innovative immuno-oncology and precision medicines to address the unmet medical needs of cancer patients in China and worldwide. Established in 2015, CStone has assembled a world-class management team with extensive experience in innovative drug development, clinical research, and commercialization. The company has built an oncology-focused pipeline of 15 drug candidates with a strategic emphasis on immuno-oncology combination therapies. Currently, 5 late-stage candidates are at pivotal trials. With an experienced team, a rich pipeline, a robust clinical development-driven business model and substantial funding, CStone's vision is to become globally recognized as a leading Chinese biopharmaceutical company by bringing innovative oncology therapies to cancer patients worldwide.

For more information about CStone Pharmaceuticals, please visit: www.cstonepharma.com

Blueprint Medicines - Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding plans and timelines for the development of fisogatinib, including the timing, design, implementation, enrollment, plans and announcement of results regarding Blueprint Medicines' ongoing and planned clinical trials for fisogatinib; the potential benefits of fisogatinib and CS1001 in treating patients with locally advanced or metastatic HCC either as monotherapy or combination therapy; and Blueprint Medicines' strategy, goals and anticipated milestones, business plans and focus. The words "may," "will," "could," "would," "should," "expect," "plan," "anticipate," "intend," "believe," "estimate," "predict," "project," "potential," "continue," "target" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks and uncertainties related to the delay of any current or planned clinical trials or the development of Blueprint Medicines' drug candidates; Blueprint Medicines' ability to successfully demonstrate the safety and efficacy of its drug candidates and gain approval of its drug candidates on a timely basis, if at all; the preclinical and clinical results for Blueprint Medicines' drug candidates, which may not support further development of such drug candidates; actions of regulatory agencies, which may affect the initiation, timing and progress of clinical trials; Blueprint Medicines' ability to develop and commercialize companion diagnostic tests for its current and future drug candidates; and the success of Blueprint Medicines' current and future collaborations and licensing arrangement, including its collaboration with CStone Pharmaceuticals. These and other risks and uncertainties are described in greater detail in the section entitled "Risk Factors" in Blueprint Medicines' filings with the Securities and Exchange Commission (SEC), including Blueprint Medicines' most recent Quarterly Report on Form 10-Q and any other filings that Blueprint Medicines has made or may make with the SEC in the future. Any forward-looking statements contained in this press release represent Blueprint Medicines' views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, Blueprint Medicines explicitly disclaims any obligation to update any forward-looking statements.

CStone - Cautionary Note Regarding Forward-Looking Statements

The forward-looking statements made in this article relate only to the events or information as of the date on which the statements are made in this article. Except as required by law, we undertake no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, after the date on which the statements are made or to reflect the occurrence of unanticipated events. You should read this article completely and with the understanding that our actual future results or performance may be materially different from what we expect. In this article, statements of, or references to, our intentions or those of any of our Directors or our Company are made as of the date of this article. Any of these intentions may alter in light of future development.

SOURCE Blueprint Medicines Corporation

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