Ascentage Pharma announced that the Center for Drug Evaluation (CDE) of China'sNational Medical Product Administration (NMPA) has approved a global registrational Phase III study of the company's novel drug candidate olverembatinib (HQP1351), in patients with succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumor (GIST) who had failed prior systemic treatment. This approval marks a major milestone in Ascentage Pharma's clinical development in solid tumors. This global, multicenter, single-arm, open-label, pivotal registrational Phase III study is designed to evaluate the efficacy and safety of olverembatinib in patients with SDH-deficient GIST.

The CDE has agreed that results from the study can be used to support a future New Drug Application (NDA) for olverembatinib in SDH-GIST. GIST is the most common type of soft tissue sarcoma that arises in the gastrointestinal track, with a global incidence of 1-1.5/100,000 per year.1 KIT and PDGFRA are key genetic drivers of GIST, and 85% - 90% of all patients with GIST harbor KIT or PDGFRA mutations. The introduction of tyrosine kinase inhibitors (TKIs) has improved the prognosis of patients with this subset of GIST.

However, 85% of pediatric patients and 10%-15% of adult patients with GIST do not harbor KIT or PDGFRA mutations, thus belong to a subtype dubbed wild-type GIST. Depending on whether the SDH expression is lost in the patient, wide-type GIST can be further categorized into SDH-deficient and non-SDH-deficient GISTs.2-3 SDH-deficient GIST has unique clinical and pathological characteristics. According to existing literatures, SDH-deficient GIST has a median age of diagnosis of 21 years and is more common in women.

SDH-deficient GIST, primarily arises in the gastric area with a high propensity to metastasize, is characterized in immunohistochemistry essays by the loss of SDHB protein expression. Patients with early-stage localized SDH-deficient GIST can be treated with surgeries, although most patients eventually relapse. At present, there is no standard treatment option for relapsed and advanced SDH-deficient GISTs.

Imatinib is generally considered ineffective for the condition and other TKIs have also failed to demonstrate satisfactory efficacy2-5, offering a five-year event-free survival (EFS) rate of just 24%.4 Being commonly diagnosed at young ages, patients with SDH-deficient GIST endure significant impact on their quality of life and survival, therefore have urgent unmet medical needs for new treatment options. Olverembatinib is an orally-available novel third-generation TKI developed by Ascentage Pharma. The drug has been granted a Breakthrough Therapy Designation by the China CDE for the treatment of patients with SDH-deficient GIST who had received first-line treatment.

As a multi-targeted TKI, olverembatinib has shown excellent efficacy and manageable safety in patients with SDH-deficient GIST. Since 2022, the clinical study evaluating olverembatinib in SDH-deficient GIST has been selected for presentations at the American Society of Clinical Oncology (ASCO) Annual Meeting for three consecutive years, including an oral report at the 60th ASCO Annual Meeting just took place this month. According to the latest results, olverembatinib has achieved a clinical benefit rate (CBR) of 92.3% in patients with SDH-deficient GIST.

Olverembatinib is the first China-approved third-generation BCR-ABL inhibitor. To date, the drug has been approved for two indications in China, including adult patients with TKI-resistant chronic-phase chronic myeloid leukemia (CML-CP) or accelerated-phase CML (CML-AP) harboring the T315I mutation; and adult patients with CML-CP resistant to and/or intolerant of first-and second-generation TKIs. Olverembatinib is jointly commercialized in China by Ascentage Pharma and Innovent Biologics.