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  • CStone to release preliminary results from Phase I/II bridging study of avapritinib in Chinese patients with unresectable or metastatic gastrointestinal stromal tumors at the 2020 ASCO Annual Meeting

    Times:2020.05.28   Author:CStone

    -Avapritinib was generally well-tolerated in Chinese patients with unresectable or metastatic gastrointestinal stromal tumors (GIST), consistent with previously reported data in global study patients. No dose-limiting toxicities were observed in the study, and no patients discontinued treatment with avapritinib due to treatment-related adverse events (AEs). These data support the further evaluation of avapritinib in Chinese patients.

    -Preliminary study results show that avapritinib has demonstrated promising anti-tumor activity in Chinese patients with PDGFRA D842V -mutant GIST.

    (Suzhou, China, May 28th, 2020) - CStone Pharmaceuticals (“CStone” or the “Company”, HKEX: 2616) today announced that it will release the partial results from its Phase I/II bridging study of avapritinib, an investigational treatment developed by the company’s partner, Blueprint Medicines, in Chinese patients with unresectable or metastatic GIST.

    “We are pleased to be able to present the updated clinical data for avapritinib, a drug candidate with high therapeutic potential, at the upcoming 2020 ASCO Annual Meeting,” said Dr. Jason Yang, Chief Medical Officer of CStone. “The preliminary data from the Phase I/II bridging study of avapritinib in China show no dose-limiting toxicities, while demonstrating the strong anti-tumor activity of avapritinib in Chinese patients harboring the PDGFRA D842V mutation. The data has also helped determine the recommended dosing regimen among a Chinese patient population. CStone submitted New Drug Applications for avapritinib in Taiwan, China and mainland China in March and April this year. The preliminary safety, pharmacokinetics and efficacy data of avapritinib support its further investigation in Chinese patients.”

    This open-label, multi-center Phase I/II bridging study was designed to evaluate the safety, pharmacokinetics and anti-tumor activity of avapritinib in Chinese patients with unresectable or metastatic GIST.

    This study enrolled adult patients with unresectable or metastatic GIST who had progressed after imatinib and ≥ 1 other tyrosine kinase inhibitor, or could not tolerate standard treatment or had PDGFRA D842V mutant GIST.

    As of a data cutoff date of December 25, 2019, preliminary results from the Phase I dose-escalation study in 12 Chinese patients were consistent with previously reported data in global study patients with unresectable or metastatic GIST:

    a)   Avapritinib was generally well-tolerated at 200 mg and 300 mg once daily (QD) doses, and no dose-limiting toxicities were observed.

          Avapritinib was generally safe, and no Grade 4 or 5 AEs were reported. The most common Grade 3 TEAE was anemia (n=2), and no patients discontinued treatment with avapritinib due to treatment-related AEs.

    b)   Avapritinib was rapidly absorbed (median Tmax 2.0-4.0 hours), and the exposure increased proportionally with doses at the steady state. The mean half-life of avapritinib ranged from 42.2 to 44.4 hours, which supports the use of QD dosing.

    c)   Avapritinib has demonstrated promising preliminary anti-tumor activity in Chinese patients with PDGFRA D842V mutant GIST. Among the three patients harboring the PDGFRA D842V mutation as of the data cutoff date, two achieved partial responses (PRs) and one achieved stable disease , as assessed by investigators at the first tumor assessment.

    Based on the safety profile of avapritinib in Chinese patients, and consistent with results from the dose-escalation portion of the global NAVIGATOR study, 300 mg QD was determined to be the recommended Phase II dose for Chinese patients.

    Also at the 2020 ASCO Annual Meeting, CStone’s partner, Blueprint Medicines plans to present updated data on pralsetinib in advanced RET fusion-positive non-small cell lung cancer, thyroid cancer and other solid tumors.

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

    ***

    About Avapritinib

    Avapritinib is an investigational, selective and potent inhibitor of KIT and PDGFRA mutant kinases.

    Avapritinib is a kinase inhibitor approved by the U.S. Food and Drug Administration under the brand name AYVAKIT™ for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations.

    Avapritinib is not approved for the treatment of any other indication in the U.S., or for the treatment of any indication by the National Medical Products Administration in mainland China or by any other health authority in any other jurisdiction.

    Blueprint Medicines, a partner of CStone, is pursuing a broad clinical development program for avapritinib for the treatment of advanced, smoldering and indolent systemic mastocytosis.


    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

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