Suzhou, China, September 23, 2025—CStone Pharmaceuticals (“CStone,” HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, autoimmune/inflammation, and other key disease areas, today announced that the first patient has been enrolled in Australia in the global multicenter Phase II clinical trial of core asset CS2009 (PD-1/VEGF/CTLA-4 trispecific antibody). The trial enrollment is currently ongoing in Australia and China, with subsequent expansion planned for the United States.
Phase I Dose-Escalation Study Demonstrates Promising Profile
In the Phase I dose-escalation study (6 cohorts, 1-45mg/kg, escalation and backfilling), CS2009 showed:
- Favorable Safety: No dose-limiting toxicities (DLT) observed across all evaluated doses, and well-tolerated in dozens of patients.
- PK/PD Characteristics as Expected:
- Broad & Deepening Antitumor Activity:
Phase I data will be presented at the European Society for Medical Oncology (ESMO) Congress in October 2025.
Global Phase II Trial Design Across Multiple Tumors
The multi-cohort expansion trial will evaluate CS2009 monotherapy and combination regimens across 15 cohorts covering multiple solid tumor indications:
- Non-Small Cell Lung Cancer (NSCLC):
- Hepatocellular Carcinoma (HCC): Monotherapy in unresectable advanced HCC after ≤2 prior systemic therapies.
- Colorectal Cancer (CRC): Combination with chemotherapy in first-line proficient mismatch repair/microsatellite stable (pMMR/MSS) patients.
- Platinum-Resistant Ovarian Cancer (PROC):
- Triple-Negative Breast Cancer (TNBC):
- Extensive-Stage SCLC (ES-SCLC): Combination with chemotherapy as first-line treatment.
- Cervical Cancer (CC): Combination with chemotherapy as first-line treatment.
- Gastric/Gastroesophageal Junction Cancer (GC/GEJC): Combination with chemotherapy as first-line treatment.
- Esophageal Squamous Cell Carcinoma (ESCC): Combination with chemotherapy as first-line treatment.
About CS2009 (PD-1/VEGF/CTLA-4 Trispecific Antibody)
CS2009 is a novel trispecific antibody targeting PD-1, VEGFA, and CTLA-4 to achieve multidimensional antitumor effects through synergistic mechanisms. It is independently developed by CStone from molecular inception, with the potential to be first- or best-in-class. Its differentiated molecular design combines these validated targets, preferentially invigorating exhausted tumor infiltrating lymphocytes (TILs) while demonstrating VEGF neutralization comparable to existing anti-VEGF antibodies. CS2009 covers a wide range of cancers, including but not limited to non-small cell lung cancer, small cell lung cancer, hepatocellular carcinoma, gastric cancer, ovarian cancer, cervical cancer, breast cancer, colorectal cancer, esophageal cancer etc.
About CStone
CStone (HKEX: 2616), established in late 2015, is an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, autoimmune/inflammation, and other key disease areas. Dedicated to addressing patients’ unmet medical needs in China and globally, the Company has made significant strides since its inception. To date, the Company has successfully launched 4 innovative drugs and secured approvals for 16 new drug applications covering 9 indications. The company’s pipeline is balanced by 16 promising candidates, featuring potentially first-in-class or best-in-class antibody-drug conjugates (ADCs), multispecific antibodies, immunotherapies and precision medicines. CStone also prides itself on a management team with comprehensive experiences and capabilities that span the entire drug development spectrum, from preclinical and translational research to clinical development, drug manufacturing, business development, and commercialization.
For more information about CStone, please visit: www.cstonepharma.com.
IR contact: ir@cstonepharma.com
PR contact: pr@cstonepharma.com
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