CStone announces first patient enrollment in the U.S. in the Phase 1 clinical trial of CS5001, a potential global best-in-class ROR1-targeting ADC

• Commencement of the first-in-human clinical trial of CS5001 marks another key milestone for CStone's Pipeline 2.0 
• Global development of CS5001 is conducted in the form of a multi-regional clinical trial, with sites initiated in the US and Australia, and an IND application accepted by the NMPA in China
• As one of the most advanced ROR1 ADCs in clinical development, CS5001 has demonstrated therapeutic potential in multiple hematological and solid malignancies

SUZHOU, China, March 30, 2022 /PRNewswire/ -- CStone Pharmaceuticals ("CStone", HKEX: 2616), a leading biopharmaceutical company focused on the research, development, and commercialization of innovative immuno-oncology therapies and precision medicines, today announced that the first patient has been enrolled in the U.S. in the Phase 1 clinical trial for CS5001. This is a remarkable milestone for CStone's Pipeline 2.0 strategy.

CS5001 is a potential global best-in-class antibody-drug conjugate (ADC), targeting receptor tyrosine kinase-like orphan receptor 1 (ROR1). As one of the three most advanced ROR1 ADCs worldwide, CS5001 has been approved for the initiation of a multi-regional clinical trial in the US and Australia. The China National Medical Products Administration (NMPA) has accepted the investigational new drug (IND) application of CS 5001. This first-in-human Phase 1 study aims to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of CS5001 in advanced B cell lymphomas and solid tumors.

ROR1 is an oncofetal protein with low or no expression in adult tissues but high expression in a variety of cancers including various forms of leukemia and non-Hodgkin lymphoma, breast, lung, and ovarian cancers, making it an ideal ADC target. Results from pre-clinical studies showed that CS5001 exhibited potent and selective cytotoxicity to a variety of ROR1-expressing cancer cell lines and demonstrated remarkable in vivo antitumor activity in both hematological and solid tumor xenograft models. The preclinical data were presented as a late-breaking abstract at the 33rd AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics 2021.

Dr. Archie Tse, Chief Scientific Officer of CStone, said: "We are very glad to have the first patient enrolled in the first-in-human study of CS5001. This potentially best-in-class ROR1 ADC contains a number of differentiated features which may translate into a wider therapeutic window against a variety of cancer types -- a fully human antibody backbone, proprietary site-specific conjugation, and tumor-cleavable linker and prodrug technology. Results from the preclinical studies of CS5001 already showed its therapeutic potential in ROR1-expressing hematological and solid malignancies. We will swiftly execute the global development program of CS5001, starting with this Phase 1 study to characterize its safety and preliminary efficacy in the treatment of advanced B-cell lymphoma and selected solid tumors."

About CS5001（ROR1 ADC）

CS5001 is a clinical-stage antibody-drug conjugate (ADC) targeting ROR1 (receptor tyrosine kinase-like orphan receptor 1). CS5001 has uniquely designed and LCB's proprietary tumor-cleavable linker and pyrrolobenzodiazepine (PBD) prodrug. Only after reaching the tumor, the linker and prodrug are cleaved to release the PBD toxin, resulting in lethal DNA cross-links in cancer cells. The use of the linker plus PBD prodrug effectively helps addressing the toxicity problem associated with traditional PBD payloads, leading to a better safety profile. Additionally, CS5001 utilizes site-specific conjugation for a precise drug antibody ratio of 2 which enables homogeneous production and large-scale manufacturing.

In October 2020, CStone signed a licensing agreement with LegoChem Biosciences, Inc. (LCB) for the development and commercialization of CS5001 which was originally generated by collaboration of LCB and ABL Bio, both South Korea-based leading biotech companies. Under the agreement, CStone obtains the exclusive global right to lead development and commercialization of CS5001 outside the Republic of Korea.

About CStone

CStone Pharmaceuticals (HKEX: 2616) is a biopharmaceutical company focused on research, development, and commercialization of innovative immuno-oncology and precision medicines to address the unmet medical needs of cancer patients in China and worldwide. Established in 2015, CStone has assembled a world-class management team with extensive experience in innovative drug development, clinical research, and commercialization. The company has built an oncology-focused pipeline of 15 drug candidates with a strategic emphasis on immuno-oncology combination therapies. Currently, CStone has received seven NDA approvals for four drugs. CStone's vision is to become globally recognized as a world-renowned biopharmaceutical company by bringing innovative oncology therapies to cancer patients worldwide.

For more information about CStone, please visit: www.cstonepharma.com.

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SOURCE CStone Pharmaceuticals