Suzhou, China, October 7^th, 2024 — CStone Pharmaceuticals (HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of anti-cancer therapies, today announced a presentation at the 39^th Annual Meeting of the Society for Immunotherapy of Cancer (SITC), reporting preclinical data of CS2009, one of the key assets in CStone Pipeline 2.0 targeting PD-1, CTLA-4, and VEGFa. The SITC meeting will be held from November 6 to 10, 2024, in Houston, USA.

• Presentation Format: Poster
• Abstract Title: CS2009, a novel first-in-class trispecific antibody targeting PD-1, CTLA-4, and VEGFa, demonstrates promising anti-tumor activity in preclinical evaluation
• Abstract Number: 504
• Presentation Date: November 8-9, 2024 (EST)

As a key asset in CStone's Pipeline 2.0, CS2009 is a potentially first-in-class/best-in-class, next-generation I/O backbone that targets three critical immune suppressive pathways in tumor microenvironment: PD-1, CTLA-4, and VEGFa, with the ability to reinvigorate exhausted tumor-infiltrating T cells (TILs) and demonstrate comparable VEGFa neutralization versus existing anti-VEGFa antibodies. CS2009 is expected to enhance the potency of PD-(L)1-based therapies, thus it could potentially cover a broader range of indications, including non-small cell lung cancer, ovarian cancer, renal cell carcinoma, cervical cancer, hepatocellular carcinoma, and gastric cancer. Moreover, aided by the anti-CTLA-4 arm, CS2009 could potentially benefit patients with low or negative PD-L1 expression who are not sensitive to anti-PD-(L)1 therapies.

Preclinical data has demonstrated that CS2009 exhibits superior anti-tumor activity in immune-competent mouse models, compared to potential competitors, such as PD-(L)1/CTLA-4 and PD-(L)1/VEGFa bispecific antibodies. CS2009 is currently in Investigational New Drug (IND)-enabling stage, and we expect to submit IND application by the end of 2024 or in early 2025, followed by initiation of the first-in-human trial in early 2025.

About CS2009 (PD-1, CTLA4 and VEGFa Trispecific Antibody)

CS2009 is a trispecific antibody targeting PD-1, CTLA-4, and VEGFa, with first-in-class/best-in-class potential for major tumor types. CS2009 has a differentiated molecular design that combines three clinically validated targets, preferentially invigorating exhausted TILs and demonstrating VEGFa neutralization comparable to existing anti-VEGFa antibodies. It covers a wide range of cancers, including non-small cell lung cancer, ovarian cancer, renal cell carcinoma, cervical cancer, hepatocellular carcinoma, and gastric cancer.

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 15 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 bjjmwy.com.cn.

IR contact: ir@cstonepharma.com

PR contact: pr@cstonepharma.com

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