CStone Submits Clinical Trial Application in Australia for CS5001 (ROR1 ADC) in Combination with First-Line Standard-of-Care for DLBCL

• Phase Ib trial to evaluate CS5001 in combination with R-CHOP as a first-line treatment for diffuse large B-cell lymphoma (DLBCL), aiming to reshape the standard-of-care landscape.
• CS5001 is also being investigated globally in a multi-center Phase Ib clinical trial for multiple solid tumor types.

SUZHOU, China, March 6, 2025 /PRNewswire/ -- CStone Pharmaceuticals ("CStone", HKEX: 2616), a biopharmaceutical company dedicated to developing innovative cancer therapies, today announced the submission of a Phase Ib clinical trial application in Australia for CS5001, its ROR1-targeting antibody-drug conjugate (ADC), in combination with first-line standard-of-care (SoC) for DLBCL. CS5001 is also being evaluated as both a monotherapy and in combination with a PD-L1 inhibitor for advanced solid tumors in an ongoing global multi-center clinical trial.

Building on promising data from CS5001 monotherapy in later-line aggressive and indolent lymphomas, this Phase Ib trial aims to expand the therapeutic potential of CS5001 across all DLBCL stages and solid tumors. The study will explore:

• CS5001 + R-CHOP: First-line treatment for DLBCL patients who have not received prior systemic therapy.
• CS5001 + SoC: For patients with relapsed or refractory DLBCL.
• CS5001 Monotherapy: Targeting ROR1-expressing solid tumors.
• CS5001 + Sugemalimab: Combination therapy for advanced solid tumors.

Dr. Jason Yang, CEO, President of R&D, and Executive Director at CStone, stated: "We are thrilled to reach another key clinical milestone for CS5001. The existing data underscore its broad potential in both lymphomas and solid tumors. Notably, a ROR1 ADC combined with R-CHP has demonstrated an impressive complete response (CR) rate in a Phase II trial for first-line DLBCL. As we advance from late-line monotherapy to frontline combination therapy, we are optimistic that CS5001 will provide significant clinical benefits to DLBCL patients and establish itself as a first-line treatment option. Meanwhile, we continue to explore CS5001's potential in solid tumors and eagerly anticipate further positive outcomes."

The global multi-center Phase Ib trial for CS5001 is actively enrolling patients across the United States, Australia, and China. Recruitment is ongoing for monotherapy cohorts targeting aggressive and indolent advanced lymphomas, which could potentially expand into a Phase II single-arm registrational study. Additional cohorts, including the first-line DLBCL combination therapy and solid tumor monotherapy and combination therapy arms, will be initiated soon.

About CS5001 (ROR1 ADC)

CS5001 is a clinical-stage antibody-drug conjugate ("ADC") targeting ROR1 (receptor tyrosine kinase-like orphan receptor 1). CS5001 has been uniquely designed with 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 address the toxicity associated with traditional PBD payloads, leading to a better safety profile. CS5001 has demonstrated complete tumor suppression in several preclinical cancer models and demonstrated favorable serum half-life and pharmacokinetic characteristics. CS5001 is a promising candidate drug with precision treatment potential in both hematologic tumors and malignant solid tumors. Additionally, CS5001 utilizes site-specific conjugation for a precise drug antibody ratio of which enables homogeneous production and large-scale manufacturing.

In October 2020, CStone signed a licensing agreement with LigaChem 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 develop and commercialize CS5001 outside the Republic of Korea.

The first-in-human data for CS5001 in patients with advanced solid tumors and lymphomas was presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting. Additionally, the latest clinical data on CS5001 as a monotherapy in patients with advanced lymphomas has recently been presented at the 66th American Society of Hematology (ASH) Annual Meeting.

CS5001 has demonstrated encouraging safety and robust anti-tumor activity in the Phase 1a dose escalation trials across 10 dose levels.

• At the tentative recommended Phase 2 dose (RP2D) of DL8 (125 μg/kg), CS5001 achieved objective response rates (ORRs) of 70% in advanced B-cell lymphoma and 100% in Hodgkin lymphoma.
• Encouraging efficacy signals were also observed in advanced solid tumors, including non-small cell lung cancer and pancreatic cancer.
• CS5001 was well tolerated in heavily pre-treated patients with advanced B-cell lymphomas and solid tumors.

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.

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