Global Registrational Phase III Study of Olverembatinib for the Treatment of Patients with SDH-Deficient GIST Approved by the China CDE

SUZHOU, China, and ROCKVILLE, Md., June 11, 2024 /PRNewswire/ -- Ascentage Pharma (6855.HK), a global biopharmaceutical company engaged in developing novel therapies for cancer, chronic hepatitis B (CHB), and age-related diseases, announced today that the Center for Drug Evaluation (CDE) of China's National 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 efficacy^2-5, 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.

"In earlier studies, olverembatinib has already shown encouraging efficacy and favorable safety in patients with SDH-deficient GIST," said Dr. Yifan Zhai, Chief Medical Officer of Ascentage Pharma. "We are excited by the approval for this global registrational Phase III study because it could potentially lead to a clinical breakthrough for another indication that currently lacks approved treatment options while marking a major milestone for Ascentage Pharma's clinical development in solid tumors. Remaining steadfastly committed to the mission of addressing unmet clinical needs in China and around the world, we will expeditiously advance this clinical development program for the benefit of more patients."

References

1. Mantese G. Gastrointestinal stromal tumor: epidemiology, diagnosis, and treatment. Curr Opin Gastroenterol. 2019; 35(6): 555-559.
2. Call JW, Wang Y, Rothschild S, et al. Treatment responses in SDH-deficient GIST. LRG Science, https://liferaftgroup.org/2019/08/treatmentresponses-in-sdh-deficient-gist-2/(2019, accessed 4 May 2022).
3. Nannini M, Rizzo A, Indio V, et al. Targeted therapy in SDH-deficient GIST. Ther Adv Med Oncol. 2021; 13: 17588359211023278.
4. Weldon CB, Madenci AL, Boikos SA, et al. Surgical Management of Wild-Type Gastrointestinal Stromal Tumors: A Report From the National Institutes of Health Pediatric and Wildtype GIST Clinic. J Clin Oncol. 2017; 35(5): 523-528.
5. Mullassery D, Weldon CB. Pediatric/"Wildtype" gastrointestinal stromal tumors. Semin Pediatr Surg. 2016; 25(5): 305-310.

*Olverembatinib is an investigational drug that has not been approved for any indication outside the Chinese mainland.

About Ascentage Pharma
Ascentage Pharma (6855.HK) is a globally focused biopharmaceutical company engaged in developing novel therapies for cancers, chronic hepatitis B, and age-related diseases. On October 28, 2019, Ascentage Pharma was listed on the Main Board of the Stock Exchange of Hong Kong Limited with the stock code 6855.HK.

Ascentage Pharma focuses on developing therapeutics that inhibit protein-protein interactions to restore apoptosis, or programmed cell death. The company has built a pipeline of 9 clinical drug candidates, including novel, highly potent Bcl-2, and dual Bcl-2/Bcl-xL inhibitors, as well as candidates aimed at IAP and MDM2-p53 pathways, and next-generation tyrosine kinase inhibitors (TKIs). Ascentage Pharma is also the only company in the world with active clinical programs targeting all three known classes of key apoptosis regulators. The company is conducting more than 40 Phase I/II clinical trials, including 6 global registrational phase III studies, in the US, Australia, Europe, and China. Ascentage Pharma has been designated for multiple Major National R&D Projects, including five Major New Drug Projects, one New Drug Incubator status, four Innovative Drug Programs, and one Major Project for the Prevention and Treatment of Infectious Diseases.

Olverembatinib, the company's core drug candidate developed for the treatment of drug-resistant chronic myeloid leukemia (CML) and the company's first approved product in China, has been granted Priority Review Designations and Breakthrough Therapy Designations by the Center for Drug Evaluation (CDE) of China National Medical Products Administration (NMPA). To date, the drug had been included into the China 2022 National Reimbursement Drug List (NRDL). Furthermore, olverembatinib has been granted an Orphan Drug Designation (ODD) and a Fast Track Designation (FTD) by the US FDA, and an Orphan Designation by the EMA of the EU. To date, Ascentage Pharma has obtained a total of 16 ODDs from the US FDA and 1 Orphan Designation from the EMA of the EU for 4 of the company's investigational drug candidates.

Leveraging its robust R&D capabilities, Ascentage Pharma has built a portfolio of global intellectual property rights and entered into global partnerships with numerous renowned biotechnology and pharmaceutical companies and research institutes such as UNITY Biotechnology, MD Anderson Cancer Center, Mayo Clinic, Dana-Farber Cancer Institute, MSD, and AstraZeneca. The company has built a talented team with global experience in the discovery and development of innovative drugs and is setting up its world-class commercial manufacturing and Sales & Marketing teams. One pivotal aim of Ascentage Pharma is to continuously strengthen its R&D capabilities and accelerate its clinical development programs, in order to fulfil its mission of addressing unmet clinical needs in China and around the world for the benefit of more patients.

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