Transcenta Presented Safety / Tolerability and Preliminary Anti-tumor Activity Data in Gastric and Pancreatic Cancers of TST001 Monotherapy from China Phase I Clinical Trial at the 2022 International Gastric Cancer Congress

Transcenta Holding Limited (“Transcenta”) (HKEX: 06628), a clinical stage biopharmaceutical company with fully-integrated capabilities in discovery, research, development and manufacturing of antibody-based therapeutics, announces that Transcenta has presented the safety/tolerability and preliminary anti-tumor activity data in gastric and pancreatic cancers of TST001 China phase I clinical trial as a poster presentation at the 2022 International Gastric Cancer Congress (IGCC).

The primary objectives of this phase I study (NCT04495296) are to evaluate the safety and tolerability, to identify MTD and recommended phase 2 dose (RP2D) in patients with advanced or metastatic solid tumors who progressed on or after standard treatments. Secondary objectives include the assessment of pharmacokinetic parameter, immunogenicity, and preliminary anti-tumor activity.

In the dose escalation phase, patients without preselection of tumor Claudin18.2 expression were given increasing doses of TST001 intravenously every 3 weeks (Q3W) using a 3+3 design. As of November 23rd, 2021, 11 patients had been treated at the dose levels of 3, 6, and 10 mg/kg Q3W. 9 patients were DLT evaluable with no DLT reported and MTD has not been reached. TST001 demonstrated a roughly linear PK profile as both Cmax and AUC increased proportionally across the dose range following the first dose. No drug accumulation was observed in Q3W cohort. 10 mg/kg Q3W was designated as RP2D for further expansion study and additional patients with Claudin18.2 overexpression were enrolled into the expansion phase at the 10 mg/kg Q3W dose. The most common AEs (>20%) included nausea, vomiting, anemia, hypoalbuminemia, abdominal distension, constipation. In terms of efficacy, one patient in the 6 mg/kg Q3W dose-escalation cohort who progressed on multiple lines of chemotherapies, anti-PD1 and anti-VEGF therapies achieved a confirmed partial response at week 12. Post the data cut-off date, additional confirmed PRs were observed at recommended phase 2 dose in the newly enrolled monotherapy expansion cohorts including gastric cancer and pancreatic cancer patients with Claudin18.2 expression. One pancreatic cancer patient with medium-low Claudin 18.2 expression achieved 82% tumor reduction at 12 weeks post-treatment. Enrollment of patients for the monotherapy expansion cohorts is ongoing and full data will be updated and reported in future medical conference.

In this Phase 1 clinical study, TST001 demonstrated a manageable & tolerable safety profile in patients with advanced solid tumors and preliminary anti-tumor activity in a heavily pretreated gastric and pancreatic cancer patient expressing Claudin18.2.

“Claudin18.2 is an ideal target with great anti-tumor potential for cancer treatment. TST001, a high affinity Claudin18.2 humanized antibody, is safe and displayed promising anti-tumor activity in Claudin18.2 over-expressing gastric and pancreatic cancer patients.” said Dr. Michael Shi, EVP, Head of Global R&D and CMO of Transcenta, “We will continue to characterize the safety and anti-tumor activities of the monotherapy in various Claudin18.2 expressing solid tumors as well as combination therapy with standard of care for first line gastric cancer. We believe TST001 could offer new and more effective treatment options for gastric cancer patients.”

“Gastric cancer is one of the highly prevalent malignant tumor types in China. In recent years, Claudin18.2 has emerged as a promising cancer treatment target for gastric cancer beyond HER2 and PD-L1. TST001 is the second most advanced global program targeting Claudin 18.2 and has shown promising signals of anti-tumor activities with manageable safety profile. I look forward to the start of the global phase III registration-enabling trial for testing TST001 as the treatment for first line gastric cancer,” said Professor Lin Shen from Beijing Cancer Hospital.

Source: Transcenta Holding Limited