CSPC Pharma Releases Latest Studies on SYSA1801 at ASCO Annual Meeting

The Annual Meeting of American Society of Clinical Oncology (ASCO) was held in Chicago on February 2-6, 2023. It was the largest scale academic conference on cancer research in the world where top-notch scientists, research institutions and pharmaceutical companies in the global cancer research community officially announced the latest study results. CSPC Pharmaceutical Group also released the study results of several products at this academic gathering. Recently, we will sort out and present these study results one after another. 

Study Summary 

The results of Phase I clinical study of SYSA1801 (Recombinant Anti-human CLDN18.2 Monoclonal Antibody-MMAE Conjugate Drug) in the treatment of patients with advanced malignant solid tumor expressing CLDN18.2, led by Professor Shen Lin of Peking University Cancer Hospital, were displayed in the form of wall poster (No.3016) at the 2023 ASCO Annual Meeting. The results showed the good anti-tumor activity of SYSA1801. 

It is a multi-center phase I clinical study (NCT05009966), which aims to evaluate the safety, tolerability, pharmacokinetics, immunogenicity and preliminary efficacy of SYSA1801 in the treatment of patients with advanced malignant solid tumor patients expressing CLDN18.2. 

Study Contents 

As of November 5, 2022, 33 subjects were enrolled, including 26 cases of gastric cancer and 7 cases of pancreatic cancer. Twenty-five subjects (75.8%) were observed with adverse events (TRAE) related to the investigational drug, of which 8 patients (24.2%) experienced Grade 3 or above TRAEs. Twenty-one subjects, including 17 subjects with gastric cancer, were available for evaluating the efficacy. The ORR and DCR of gastric cancer population were 47.1% (95%CI 23.0-72.2%, 8PRs) and 62.7% (95%CI 38.3-85.8%, 3SDs), respectively. In addition, two subjects with gastric cancer were observed with particularly significant response, i.e. 1 subject who previously failed the therapy targeting CLDN18.2 monoclonal antibody achieved a PR after administration of SYSA1801, and the other subject achieved a lasting PR after administration of SYSA1801, which has been lasting as long as 44 weeks by the deadline. 

Study Results 

The preliminary results showed the very promising anti-tumor effect of SYSA1801 in advanced malignant solid tumors with CLDN18.2 expression, especially in gastric cancer. SYSA1801 is safe and well-tolerated in the dosage range, and the studies of the dose expansion phase are currently in process. 

SYSA1801 Injection is a recombinant anti-human CLDN18.2 monoclonal antibody -MMAE conjugate drug developed by CSPC Pharmaceutical Group. It is composed of an anti-CLDN18.2 fully humanized monoclonal antibody conjugated with an MMAE derivative (LND002) on Q295 amino acid of each heavy chain; and by selectively binding to CLDN18.2 receptor ring I, lysosomes in target cells degrade and release active chemotherapy drug MMAE to achieve the anti-cancer effect. 

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