CStone Pharmaceuticals Announces First Patient Dosed in Global Clinical Trial of CS1001 Combined with Bayer’s Regorafenib

SUZHOU, China, Jan. 24, 2020 /PRNewswire/ -- CStone Pharmaceuticals (Suzhou) Co., Ltd. ("CStone Pharmaceuticals" or the "Company," HKEX stock code: 2616) recently announced that the first patient has been dosed in Australia in a study evaluating the combination of its investigational PD-L1 inhibitor, CS1001, and regorafenib, an oral multi-kinase inhibitor developed by Bayer. This marks the first global proof-of-concept clinical study under the collaboration between the two parties, aiming to explore the recommended dose of CS1001 in combination with regorafenib, and to assess the safety, tolerability, pharmacokinetics, and anti-tumor efficacy of this regimen in the treatment of various cancers, including gastric cancer.

CS1001 is an investigational anti-PD-L1 monoclonal antibody independently developed by CStone Pharmaceuticals. Currently, CS1001 is undergoing multiple clinical trials. In addition to a U.S. bridging Phase I trial, CS1001 is being evaluated in China through a multi-arm Phase Ib trial, two registrational Phase II trials, and four Phase III trials across various cancer types. According to data presented at the 2019 Chinese Society of Clinical Oncology (CSCO) Annual Meeting, CS1001 demonstrated favorable antitumor activity and tolerability in multiple cancer types during Phase Ia and Ib studies.

Regorafenib is an oral multi-kinase small-molecule inhibitor developed by Bayer, targeting VEGFR, FGFR, CSF1R, and other kinases. Currently, regorafenib has been approved in more than 90 countries, including China, for the treatment of second-line or later advanced colorectal cancer, advanced gastrointestinal stromal tumors, and advanced hepatocellular carcinoma.

In May 2019, CStone Pharmaceuticals and Bayer AG entered into a global clinical collaboration study, with CStone Pharmaceuticals serving as the sponsor of the clinical study evaluating CS1001 in combination with regorafenib, and Bayer AG providing the regorafenib required for the trial.

Multiple studies have demonstrated the efficacy of kinase inhibitor monotherapy or anti-PD-1/PD-L1 antibody monotherapy in the treatment of various tumor types. Meanwhile, preclinical studies indicate that targeted agents such as regorafenib can enhance the efficacy of immune checkpoint inhibitors by modulating the immune microenvironment of certain solid tumors. Therefore, the combination of these two mechanisms of action may exert a synergistic effect on tumor regression.

Dr. Jiang Ningjun, Chairman and Chief Executive Officer of CStone Pharmaceuticals, stated, “This clinical trial, conducted jointly by CStone Pharmaceuticals and Bayer, represents a significant step in the company’s global strategy. We are pleased to see the first patient dosed in the study evaluating the combination therapy of CS1001 and regorafenib. We hope that this collaborative exploration will not only complement our product pipeline but also benefit more cancer patients who lack effective treatment options.”

Dr. Xie Yizhao, Chief Translational Medicine Officer at CStone Pharmaceuticals, stated, “Preclinical studies in animal disease models have demonstrated that the combination of CS1001 and regorafenib enhances antitumor efficacy, providing data support for the initiation of this clinical study. Meanwhile, numerous international trials are currently investigating similar combination therapies for advanced or metastatic solid tumors, with some promising results already reported. We are highly optimistic about the clinical trial outcomes of CS1001 in combination with regorafenib.”

About Bavencio^®(Regorafenib)

Regorafenib is an oral multi-kinase inhibitor that blocks multiple protein kinases involved in tumor angiogenesis (VEGFR1, -2, -3, TIE2), tumor proliferation (KIT, RET, RAF-1, BRAF), tumor metastasis (VEGFR3, PDGFR, FGFR), and tumor immunity (CSF1R).

Regorafenib is a compound developed by Bayer. In 2011, Bayer reached an agreement with the biopharmaceutical company Onyx. Under the agreement, Onyx would receive royalties based on the global net sales of regorafenib in the oncology field.

Currently, regorafenib has been approved in more than 90 countries for the treatment of metastatic colorectal cancer (mCRC), metastatic gastrointestinal stromal tumors (GIST), and second-line advanced hepatocellular carcinoma (HCC). The drug is marketed under the brand name Stivarga.^®（Stivarga^®), the countries where it has been approved include the United States, European Union member states, China, and Japan.

About CS1001

CS1001 is an investigational anti-PD-L1 monoclonal antibody developed by CStone Pharmaceuticals. Generated using the OMT transgenic animal platform licensed from Ligand Pharmaceuticals of the United States, this platform enables one-stop production of fully human antibodies. As a fully human, full-length anti-PD-L1 monoclonal antibody, CS1001 closely resembles the natural human immunoglobulin G4 (IgG4). Compared with similar agents, CS1001 carries a lower risk of immunogenicity and related toxicities in patients, conferring potential unique advantages in terms of safety.

CS1001 has completed dose escalation in Phase I clinical studies in China. In the Phase Ia and Ib studies, CS1001 demonstrated favorable anti-tumor activity and tolerability across multiple indications.

Currently, CS1001 is undergoing multiple clinical trials. In addition to a U.S. bridging Phase I trial, CS1001 is being evaluated in China through a multi-arm Phase Ib trial across multiple cancer types, two registrational Phase II trials, and four Phase III trials.

About CStone Pharmaceuticals

CStone Pharmaceuticals (HKEX: 2616) is a biopharmaceutical company focused on the development and commercialization of innovative immuno-oncology and precision medicine therapies to address the urgent medical needs of cancer patients in China and globally. Established in late 2015, CStone has assembled a world-class management team with extensive experience in new drug R&D, clinical research, and commercialization. Centered on combination therapies, the company has built a robust oncology pipeline comprising 15 candidate drugs. Currently, five late-stage candidates are in or approaching pivotal trials. Leveraging its experienced team, rich pipeline, strong clinical development-driven business model, and ample capital, CStone aims to become a globally recognized leading Chinese biopharmaceutical company by delivering innovative oncology treatments to cancer patients worldwide.

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