Key Efficacy Outcomes

Median overall survival (mOS) was 20.4 months in all 82 patients enrolled.

In 26 patients with CLDN18.2 expression ≥40% (2+ intensity) and known PD-L1 CPS, mOS reached 21.7 months, mPFS 16.6 months, cORR 68%, and mDoR 16.5 months at a 22.6-month median follow-up. 

PRINCETON, N.J. and SUZHOU, China, June 2, 2025 -- Transcenta Holding Limited ("Transcenta") (HKEX: 06628), a global clinical stage biopharmaceutical company with fully-integrated capabilities in discovery, research, development and manufacturing of antibody-based therapeutics, announced updated results from the Cohort-G of an ongoing Phase II trial of Osemitamab (TST001) plus Nivolumab and CAPOX as the first-line treatment for patients with advanced G/GEJ cancer (TranStar102). The findings were showcased in a poster presentation (Abstract #4032) at the 2025 ASCO Annual Meeting in Chicago, IL, U.S.

New data, reinforcing earlier encouraging results from the Osemitamab (TST001) triple combo trial, revealed a median overall survival (mOS) of 20.4 months in all 82 patients enrolled in the study regardless of CLDN18.2 status at a median follow-up of 22.6 months. In the 26 patients who have CLDN18.2 expression on at least 40% of the tumor cells with 2+ or higher staining intensity (≥40%, ≥2+) per 14G11 IHC LDT assay and PD-L1 known, the mOS reached 21.7 months and the median progression-free survival (mPFS) was 16.6 months. The confirmed objective response rate (cORR) was 68% with a median duration of response (mDoR) of 16.5 months in this population.

The safety profile from the updated data was consistent with previously presented data (2024 ESMO poster), and was primarily characterized by manageable on-target, off-tumor effects, such as nausea, vomiting and hypoalbuminemia, most of which were Grade 1 or 2 in severity.

Osemitamab (TST001) is the second CLDN18.2-targeting antibody in global development and has received Orphan Drug Designation from the U.S. FDA for the treatment of patients with gastric or gastroesophageal junction (G/GEJ) and pancreatic cancers. Patient enrollment for the Phase I/II clinical trial in China (NCT04495296) is complete, and the study is now in the follow-up stage. Phase III trial initiation is currently underway.

"The updated Cohort-G data indicates that Osemitamab (TST001), when used in combination with checkpoint inhibitor and chemotherapy, can deliver prolonged overall survival and progression-free survival benefits especially for patients with CLDN18.2≥40%, ≥2+ expression regardless of PD-L1 CPS compared with the historical data of existing standard of care or emerging therapies,” said Dr. Charlie Qi, Executive Vice President, Head of Global Clinical Development at Transcenta. “These favorable outcomes deepen our commitment to advance this treatment through accelerated clinical trials, with the ultimate goal of making it available to patients globally.”

"Our confidence in the Osemitamab (TST001) triple combo trial is further strengthened by this updated Cohort-G data,” said Professor Lin Shen, Director, Department of Gastrointestinal Oncology and Phase I Clinical Trial Center at Peking University Cancer Hospital; and Principal Investigator of the trial. “These promising data suggest that Osemitamab (TST001) can offer meaningful clinical benefits to patients with advanced G/GEJ cancer, improving their survival and quality of life."

A brief profile of the study is as follows:

Cohort-G from Transtar102 study (NCT04495296) was designed to evaluate the safety and preliminary efficacy of Osemitamab (TST001) plus Nivolumab and CAPOX as the first-line treatment in patients with G/GEJ cancer. Key eligible criteria included HER2 negative or unknown, unresectable locally advanced or metastatic G/GEJ cancer, regardless of CLDN18.2 or PD-L1 expression and treatment naïve for advanced disease. CLDN18.2 and PD-L1 status were analyzed retrospectively using IHC 14G11 LDT assay and PD-L1 IHC 28-8 pharmDx at a central laboratory.

About Osemitamab (TST001)

Osemitamab (TST001) is a high affinity humanized anti-CLDN18.2 monoclonal antibody with enhanced antibody-dependent cellular cytotoxicity ("ADCC"). It has shown potent anti-tumor activities in tumor xenograft models. Osemitamab (TST001) is the second CLDN18.2 targeting antibody being developed globally. Osemitamab (TST001) was generated using Transcenta's Immune Tolerance Breaking Technology (IMTB) platform. Osemitamab (TST001) kills CLDN18.2 expressing tumor cells by mechanisms of ADCC. Leveraging advanced bioprocessing technology, the fucose content of Osemitamab (TST001) was significantly reduced during the production, which further enhanced NK cells mediated ADCC activity of Osemitamab (TST001). Osemitamab (TST001) has been granted Orphan Drug Designation in the U.S. by FDA for the treatment of patients with gastric or gastroesophageal junction (G/GEJ) and pancreatic cancer.

About Transcenta

Transcenta (HKEX: 06628) is a clinical stage biopharmaceutical company with fully integrated capabilities in antibody-based biotherapeutics discovery, research, development and manufacturing.

Transcenta has established global footprint, with Headquarters and Discovery, Clinical and Translational Research Center in Suzhou, Process and Product Development Center and Manufacturing Facility in Hangzhou, and Clinical Development Centers in China, U.S. and Europe. Transcenta is developing 15 therapeutic antibody molecules for oncology and selected non-oncology indications including bone and kidney disorders.

For more information, please visit www.transcenta.com and https://www.linkedin.com/company/transcenta.

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