Suzhou, China, May 7 2025 – CStone Pharmaceuticals (“CStone”, HKEX: 2616), an innovation-driven biopharmaceutical company focused on anti-cancer therapies, announced today that a poster presentation of preclinical data of CS2011 (EGFR/HER3 bispecific antibody), a key asset in CStone Pipeline 2.0, has been delivered at the 2025 American Association for Cancer Research (AACR) Annual Meeting.
EGFR and HER3 are members of the human epidermal growth factor receptor (HER) family and are validated therapeutic targets in advanced solid tumors. EGFR overexpression drives tumor progression in approximately 70% of colorectal cancers (CRC), 60% of lung cancers, and over 90% of head and neck squamous cell carcinomas (HNSCC). Meanwhile, HER3 upregulation frequently emerges as a resistance mechanism to MAPK/PI3K inhibitors, EGFR tyrosine kinase inhibitors (TKIs), and hormone therapies. CS2011 is a bispecific antibody with high binding affinity to both EGFR and HER3. It effectively blocks downstream signaling of both targets, thereby inhibiting tumor growth on EGFR/HER3 positive tumor cells.
Key Highlights:
1. CS2011 targets almost all HER family signaling except HER2 homodimers, addressing tumor heterogeneity effectively.
2. CS2011 demonstrates potent binding affinity to EGFR and/or HER3 individually and enhanced dual binding affinity to EGFR and HER3 concurrently driven by avidity-based synergy.
3. CS2011 inhibits tumor growth by binding to EGFR and/or HER3-positive tumor cells.
4. CS2011 shows superior in vivo and in vitro anti-tumor activity versus potential major competitors.
（1）Compared to anti-EGFR, anti-HER3 and competing bispecific antibody, CS2011 induces faster and deeper internalization in tumor cells across varying EGFR & HER3 expression levels.
（2）CS2011 demonstrated potent inhibition of EGFR downstream signaling, comparable to anti-EGFR antibodies, and superior inhibition of HER3-mediated signaling compared to competitive bispecific antibody.
（3）CS2011 exhibited robust anti-proliferative activity in tumor cells with diverse EGFR and HER3 expression levels.
（4）In in vivo CDX tumor models, CS2011 demonstrated superior tumor-growth inhibition compared to anti-EGFR or anti-HER3 monoclonal antibodies alone and showed comparable efficacy to the combination treatment.
5. CS2011 exhibited a pharmacokinetic (PK) profile comparable to those of monoclonal antibodies in rodents.
In summary, CS2011 has demonstrated potent blockage activity on EGFR and HER3 and exhibited synergistic effects on their downstream signaling. It thereby shows the potent tumor growth inhibitory effects in in vitro and in vivo experiments. The patent of CS2011 has been filed in March 2025, and its Investigational New Drug (IND) application is expected to be submitted in the near term.
Poster Information:
【Title】CS2011: A novel bispecific antibody targeting EGFR and HER3 that demonstrates promising anti-tumor activity in preclinical evaluation
【Session Title】Growth Factor Receptors and Other Surface Antigens as Targets for Therapy 1
【Abstract Number】2927
【Date & Time】Monday, April 28, 2025, 2:00 PM - 5:00 PM ET
【Location】Poster Section 17, Board #1
About CStone
CStone (HKEX: 2616), established in late 2015, is an innovation-driven biopharmaceutical company focused on the research and development of anti-cancer therapies. 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 (NDAs) 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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