CStone Announces FDA Clearance of IND Application for Its Novel Trispecific Antibody CS2009 (PD-1/VEGF/CTLA-4) to Advance into Phase II Clinical Trial

• CS2009 (PD-1/VEGF/CTLA-4 trispecific antibody) has received Investigational New Drug (IND) clearance from the U.S. Food and Drug Administration (FDA) to initiate a Phase II clinical trial in patients with advanced solid tumors. This marks a significant milestone in the global development of this innovative immunotherapy.
• The ongoing global multicenter Phase II trial is currently enrolling patients in Australia and China. The study design includes 15 cohorts evaluating both monotherapy and combination therapy regimens across 9 solid tumor indications, including but not limited to:
  • Non-small cell lung cancer (NSCLC)
  • Colorectal cancer (CRC)
  • Triple-negative breast cancer (TNBC)
  • Extensive-stage small cell lung cancer (ES-SCLC)‌
  • Platinum-resistant ovarian cancer (PROC)
• Initial Phase I data for CS2009, previously presented at the 2025 European Society for Medical Oncology (ESMO) annual meeting, demonstrated a favorable safety profile with encouraging antitumor activities. Further clinical data from both the phase I and II is expected to be disclosed at the upcoming American Society of Clinical Oncology (ASCO) and ESMO congress later this year.

SUZHOU, China, Feb. 15, 2026 /PRNewswire/ -- 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 U.S. FDA has cleared the IND application to initiate a Phase II clinical trial of its core asset, CS2009, in patients with advanced solid tumors.

Dr. Jason Yang, CEO, President of R&D, and Executive Director at CStone, stated, "We are pleased to receive FDA clearance to proceed with the global Phase II clinical trial of CS2009. This milestone follows a productive interaction with the agency, during which they reviewed our comprehensive Phase I data—including safety and antitumor activity data collected during dose escalation and expansion—and provided alignment on key elements of the Phase II study design, including dose optimization and expansion strategies. We are now actively advancing CS2009 clinical program globally and look forward to sharing further updates as the study progresses."

About CS2009 (PD-1/VEGF/CTLA-4 Trispecific Antibody)

CS2009, an innovative trispecific antibody designed and developed by CStone, with the potential to be first- or best-in-class. It combines three clinically validated targets—PD-1, VEGFA, and CTLA-4—and exerts multidimensional anti-tumor effects through synergistic actions. Specifically, anti-PD-1 activity reverses T cell exhaustion, anti-CTLA-4 activity promotes T cell activation and proliferation, while anti-VEGFA activity blocks tumor angiogenesis and improves the tumor micro-environment (TME). In the TME, anti-PD-1 and anti-CTLA-4 activities are significantly enhanced by crosslinking with VEGFA. Meanwhile, CS2009 preferentially blocks PD-1 and CTLA-4 on double-positive tumor-infiltrating T cells while minimizing interference with CTLA-4 regulation in peripheral T cells.

The ongoing global, multicenter Phase II clinical trial of CS2009 features a multi-cohort, parallel expansion design to evaluate the efficacy, safety, tolerability, and pharmacokinetics/pharmacodynamics (PK/PD) of CS2009 as monotherapy and combination regimens. The study comprises 15 monotherapy and combination therapy cohorts across 9 solid tumor indications, including NSCLC, CRC, TNBC, ES-SCLC, PROC, cervical cancer (CC), hepatocellular carcinoma (HCC), gastric or gastroesophageal junction cancer (GC/GEJC), and esophageal squamous cell carcinoma (ESCC). The trial is actively enrolling patients in Australia and China and has received IND clearance in the U.S.

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 20 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. 

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SOURCE CStone Pharmaceuticals