CSTONE PHARMA-B(02616) showcases three new/differentiated ADC preclinical research results including CS5007 (EGFR/HER3) at AACR Annual Meeting.

CSTONE PHARMA-B (02616) announced that the company showcased the latest preclinical research results of three independently developed pipelines, including CS5007 (EGFR/HER3 ADC), CS5006 (ITGB4 ADC), and CS5008 (DLL3/SSTR2 ADC), at the American Association for Cancer Research (AACR) Annual Meeting held from April 17 to 22, 2026. The showcased CS5007 (EGFR/HER3 ADC), CS5006 (ITGB4 ADC), and CS5008 (DLL3/SSTR2 ADC) at AACR are all based on the proprietary antibody-drug conjugate (ADC) technology platform developed by CStone Pharma, which has the following features: High stability and precise release: utilizing CStone Pharma's proprietary CSL20 linker with strong hydrophilicity, enhancing loop stability; and achieving efficient tumor-selective payload release through a tandem cleavage mechanism (involving -glucuronidase and protease) Potent payload: utilizing Exatecan as the payload, a clinically validated potent topoisomerase I inhibitor that has strong bystander effects, effectively reducing multidrug resistance sensitivity. CS5007 is a bispecific ADC composed of a human IgG1 antibody targeting EGFR/HER3, CStone Pharma's proprietary hydrophilic CSL20 linker, and the clinically validated topoisomerase I inhibitor Exatecan. The drug utilizes semi-random conjugation to combine the linker payload with the antibody, with an average drug-antibody ratio (DAR) of approximately 4. CStone Pharma plans to initiate the new drug application (IND) for CS5007 in the first half of 2026. The CS5007-101 study is a single-agent dose escalation and expansion study aimed at evaluating the safety and recommended Phase 2 dose (RP2D) of CS5007 in patients with advanced solid tumors who have progressed after standard therapy, are ineligible for standard therapy, or have no effective treatment options, with an expected enrollment of 70 patients. CS5007 is a highly-promising bispecific ADC with potent anti-tumor activity and good safety and PK characteristics. Key preclinical studies have shown that CS5007 not only has high binding affinity, enabling rapid internalization in tumor cells with different levels of EGFR and HER3 expression, but also effectively inhibits downstream signaling of EGFR and HER3, thereby strongly inhibiting tumor cell proliferation. In addition, the drug exhibits potent bystander effects, inhibiting tumor growth. In summary, these robust preclinical data provide a solid scientific basis for advancing the clinical development of CS5007 in the field of solid tumors. CS5006 is a novel ADC targeting the new target ITGB4, composed of a human IgG1 antibody targeting ITGB4, CStone Pharma's proprietary hydrophilic CSL20 linker, and the clinically validated topoisomerase I inhibitor Exatecan, with an average DAR value of approximately 4. CS5006 is a very promising novel ADC with broad-spectrum potent anti-tumor activity, good safety, and PK characteristics. Key preclinical studies show that CS5006 can efficiently and specifically kill ITGB4-positive cells through rapid and deep internalization, while also clearing ITGB4-negative cells, demonstrating broad and deep in vivo anti-tumor activity in CDX models. In non-human primates (NHPs), CS5006 exhibits expected half-life and HNSTD. Furthermore, CS5006 has high antibody production, strong ADC stability, and good developmental potential. In conclusion, detailed preclinical data provide strong support for the clinical development of CS5006. CStone Pharma plans to initiate the IND application work for CS5006 in the second half of 2026. CS5008 is a bispecific ADC composed of a human IgG1 antibody targeting DLL3/SSTR2, CStone Pharma's proprietary hydrophilic CSL20 linker, and the clinically validated topoisomerase I inhibitor Exatecan, utilizing semi-random conjugation to combine the linker payload with the antibody, with an average DAR of approximately 4. CS5008 is a highly promising bispecific ADC with broad-spectrum potent anti-tumor activity, good safety, and pharmacokinetic characteristics. Key preclinical studies show that CS5008 can efficiently and specifically kill tumor cells with different levels of DLL3 and SSTR2 expression through rapid and deep internalization, showing broad and deep in vivo anti-tumor activity in CDX models. In NHPs, CS5008 exhibits good tolerability and excellent PK characteristics. Additionally, CS5008 has high antibody production, strong ADC stability, and good drug-like properties. In conclusion, detailed preclinical data provide a strong scientific basis for the clinical development of CS5008 in solid tumors including SCLC, NECs. CStone Pharma plans to officially initiate the IND application work for CS5008 in the second half of 2026.