• Preliminary results from the first-in-human (FIH) global multicenter study of CS5001 have been disclosed for the first time. As one of the two most advanced ROR1 ADCs in clinical stage globally, CS5001 has been evaluated at seven dose levels in its phase I clinical study, in which promising safety, stability and anti-tumor activity were observed in various hematological and solid malignancies. The evaluation at higher dose levels and longer follow-up is ongoing.
• The regulatory review on sugemalimab in major overseas markets such as the European Union (EU) and the United States (U.S.) is proceeding smoothly. The marketing authorization application (MAA) of sugemalimab as first-line treatment for metastatic non-small cell lung cancer (NSCLC) is under review by the European Medicines Agency (EMA) and the Medicines & Healthcare Products Regulatory Agency (MHRA) of the United Kingdom (U.K.). The EMA has already completed the inspection of one clinical site, and the remaining Good Clinical Practice (GCP) inspection is to be completed by early February of 2024 as scheduled. In addition, CStone and the U.S. Food and Drug Administration (FDA) have reached an agreement in a Type B consultation regarding the registration pathway for relapsed or refractory extranodal NK/T-cell lymphoma (R/R ENKTL) indication.
• In order to further improve the commercialization efficiency, CStone has recently established commercial collaborations with two companies to leverage their strengths while enabling CStone to strategically focus on research and development. In addition, the Company currently has multiple assets at/near IND stage and intends to advance more innovative drugs into clinical development in the near future.
• Other businesses have also been progressing recently, anticipating multiple upcoming milestones.

(Suzhou, China, December 20, 2023) CStone Pharmaceuticals (“CStone”, HKEX: 2616), a leading biopharmaceutical company focused on the research, development, and commercialization of innovative immuno-oncology therapies and precision medicines, announced that it will hold a conference on latest business update today.

Data Update on Safety and Effectiveness of ROR1 ADC

Preliminary results from the ongoing FIH global multicenter study of CS5001 have been disclosed for the first time. As one of the two most advanced ROR1 ADCs clinical stage globally, CS5001 has been evaluated at seven dose levels in its phase I clinical study, in which promising safety, stability and anti-tumor activity were observed in various hematological and solid malignancies.

• In this clinical study, dose level eight is currently being evaluated. The data from prior seven dose levels suggests that the drug is safe and well-tolerated; the majority of the adverse events observed were Grade 1 or 2; no dose limiting toxicity (DLT) was observed.
• CS5001 has exhibited anti-tumor activity in heavily pre-treated patients, with partial responses (PRs) observed in cancer types including advanced Hodgkin's lymphoma and pancreatic cancer. The evaluation at higher dose levels and continued follow-up is ongoing.
• CS5001 has demonstrated excellent human pharmacokinetics (PK) characteristics and linker stability as demonstrated by similar exposure level of ADC and total antibody in the blood.
• Updated phase I clinical data is expected to be presented at an international academic conference in the first half of next year.

Update on PD-L1 Overseas Progress

The Company is accelerating the regulatory review on sugemalimab in major global markets to further realize its asset value and is also actively engaging with potential partners worldwide. Currently, the overseas activities of sugemalimab in major markets such as the EU and the U.S. are progressing smoothly.

• The MAA of sugemalimab as first-line treatment for metastatic NSCLC is under review by the EMA and the MHRA of the U.K..The EMA has completed the inspection of one clinical site, and the remaining inspection will be completed by early February of 2024. It is expected that the regulatory decision by EMA for this indication will be received in the first half of next year.
• CStone and the FDA have reached an agreement in a Type B consultation regarding the registration pathway for R/R ENKTL indication.
• The Company will also discuss with the U.S. FDA regarding registration pathways for gastric/gastroesophageal junction (G/GEJ) adenocarcinoma and esophageal squamous cell carcinoma (ESCC) indications in the future.

Update on Commercialization Strategy

In order to further improve the commercialization efficiency, CStone has recently established commercial collaborations with two companies to leverage their strengths while enabling CStone to strategically focus on research and development going forward. In addition, the Company currently has multiple assets at/near IND stage and intends to advance more innovative drugs into clinical development in the near future.

• CStone has entered into a strategic collaboration for nofazinlimab (anti-PD-1 antibody) in Mainland China with 3SBio Inc. (“3SBio”) and granted 3SBio exclusive rights for the development, registration, manufacturing, and commercialization of nofazinlimab (anti-PD-1 antibody) in Mainland China. CStone will retain the rights to nofazinlimab outside of Mainland China. This partnership will combine the strengths of CStone and 3SBio in research and development, manufacturing, and commercialization, thus accelerating the clinical development and commercialization of nofazinlimab and benefitting more patients in mainland China.
• CStone has granted the exclusive commercial rights for GAVRETO ^® (pralsetinib), a selective rearranged during transfection (RET) inhibitor, to Allist Pharmaceuticals (“Allist”) in Mainland China.

About Other Recent Business Updates

CStone has made other business progresses recently and is expected to achieve multiple milestones in the near future:

• The supplemental biologics license application (sBLA) for sugemalimab in combination with fluorouracil and platinum-based chemotherapy as the first-line treatment for unresectable locally advanced, recurrent, or metastatic ESCC has been approved by the NMPA, making it the world’s first approved anti-PD-L1 monoclonal antibody for the first-line ESCC indication. As a result of the approval, the Company will receive a milestone payment from Pfizer for this indication. It is the fourth approved indication for sugemalimab in China following stage III and IV NSCLC and R/R ENKTL, and is also the thirteenth NDA approval received since the establishment of CStone.
• The sBLA for sugemalimab in combination with chemotherapy for the first-line treatment of locally unresectable advanced or metastatic G/GEJ adenocarcinoma has been accepted by the NMPA in China and is currently under review. It is expected to be approved in the first quarter of the next year, and upon achievement of this milestone, a regulatory milestone payment from the partner is expected.
• The global multi-regional phase III study of CS1003-305 of nofazinlimab in combination with lenvatinib versus placebo in combination with lenvatinib as the first-line treatment for patients with advanced hepatocellular carcinoma (HCC) has completed its prespecified patient enrollment and a topline readout is expected in the first quarter of 2024.

About CStone

CStone (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 management team with extensive experience in innovative drug development, clinical research, and commercialization. The company has built an oncology-focused pipeline of 14 drug candidates with a strategic emphasis on immuno-oncology combination therapies. Currently, CStone has received 13 NDA approvals for its four drugs. Multiple late-stage drug candidates are now under pivotal clinical trials or registration. CStone’s vision is to bring innovative oncology therapies to cancer patients worldwide.

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

Forward Looking Statements

There is no assurance that any forward-looking statements regarding the business development of the Group in this announcement or any of the matters set out herein are attainable, will actually occur or will be realized or are complete or accurate. The financial and other data relating to the Group as disclosed in this announcement has also not been audited or reviewed by its auditors. Shareholders and/or potential investors of the Company are advised to exercise caution when dealing in the securities of the Company and not to place any excessive reliance on the information disclosed herein. Any shareholder or potential investor who is in doubt is advised to seek advice from professional advisors.