CStone Pharmaceuticals, a leading biopharmaceutical company focused on researching, developing, and commercializing innovative immuno-oncology therapies and precision medicines, presented results from a phase 1/2 clinical study of AYVAKIT® (avapritinib) in Chinese patients with advanced GIST, via a short oral report at the virtual European Society for Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer 2021. The results bring additional clinical evidence for the treatment of patients with GIST that could potentially improve clinical practice.
Discovered by CStone's partner Blueprint Medicines, AYVAKIT is a potent, selective and orally available inhibitor of KIT and PDGFRA mutant kinases. CStone has an exclusive collaboration and license agreement with Blueprint Medicines for the development and commercialization of AYVAKIT and certain other drug candidates in Mainland China, Hong Kong, S.A.R., China, Macau, S.A.R., China and Taiwan, China. Blueprint Medicines retains development and commercial rights for AYVAKIT in the rest of the world.
The results are based on an open-label, multi-center phase I/II clinical study, evaluating the safety, pharmacokinetics and anti-tumor activity of AYVAKIT in Chinese patients with unresectable or metastatic GIST. As of a data cutoff date of July 31, 2020, safety was evaluated in 60 patients who received 200 or 300 mg once-daily dosing of AYVAKIT. Efficacy was assessed in 20 evaluable patients with PDGFRA D842V mutant GIST. Clinical activity was determined by the Independent Radiological Review Committee (IRRC), according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) version 1.1.
The updated results further confirm the significant anti-tumor activity of AYVAKIT for the treatment of patients with advanced PDGFRA D842V mutant GIST, who have a poor remission rate and prognosis using existing tyrosine kinase inhibitors. The objective response rate (ORR) was 70%, the clinical benefit rate (CBR) was 80% and the median progression-free survival (PFS) has not been reached.
AYVAKIT showed anti-tumor activity in Chinese patients with GIST in the fourth-line or later treatment setting. The ORR was 17%, the CBR was 52% and the median PFS was 5.6 months, supporting the potential of AYVAKIT for patients with GIST in later lines of therapy.
The study further demonstrated the generally well-tolerated safety profile of AYVAKIT for the treatment of Chinese patients with GIST, consistent with results observed in prior studies globally. The most common treatment-emergent adverse events were anemia, increased blood bilirubin, decreased white blood cell count, increased blood creatine phosphokinase, increased aspartate aminotransferase, face edema, eyelid edema, decreased neutrophil count and hair color changes.
Professor Lin Shen, Principal Investigator of the phase 1/2 study of AYVAKIT in Chinese patients with GIST, and Vice President of Peking University Cancer Hospital, said, "Due to the extremely limited benefits from existing therapies, patients with PDGFRA D842V mutant GIST have high medical needs. The updated data presented at ESMO GI further prove the anti-tumor activity of AYVAKIT in Chinese patients with advanced PDGFRA exon 18-mutant GIST, and these results also support the potential of AYVAKIT for patients with fourth-line and above GIST. AYVAKIT has shown a well-tolerated safety profile, and brings an important additional treatment option to patients."
Dr. Jason Yang, Chief Medical Officer of CStone, said, "We are glad to present updated results from the phase I/II bridging study of AYVAKIT in Chinese patients with GIST at the ESMO World Congress on Gastrointestinal Cancer 2021. The data show that AYVAKIT was well-tolerated in Chinese patients and further highlight the drug's anti-tumor activity in patients with GIST harboring PDGFRA exon 18 mutations, including PDGFRA D842V mutant GIST. AYVAKIT also showed potential in the fourth-line or later treatment setting for Chinese GIST patients. We expect AYVAKIT to benefit patients with GIST."
About AYVAKIT® (avapritinib)
AYVAKIT (avapritinib) is a kinase inhibitor approved by the China National Medical Products Administration (NMPA) for the treatment of adults with unresectable or metastatic GIST harboring the PDGFRA exon 1...
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