Transcenta Holding Limited has presented progression free survival (PFS) data by CLDN18.2 expression level from Phase I/II study of Osemitamab (TST001) plus Capecitabine and Oxaliplatin (CAPOX) as the first-line treatment of advanced gastric/gastroesophageal junction (G/GEJ) cancer at ESMO World Congress on Gastrointestinal Cancer 2023. These data will support the upcoming global Phase III pivotal trial to be initiated in the second half of 2023. The efficacy and safety of Osemitamab®? (TST001) plus CAPOX as the first-line treatment for patients with advanced G/GEJ cancer was explored in a dose escalation and expansion Phase I/II study in China (Cohort C of TranStar102, NCT04495296). In the expansion phase (except 8 patients from a safety run-in), CLDN18.2 positive was required, which is defined as IHC membrane staining =10% tumor cells with =1+ intensity per LDT assay, selecting approximately 55% of the screened patients. Study Results: As of April 21, 2023, a total number of 64 patients were dosed with Osemitamab (TST001) in combination with CAPOX, 15 patients received Osemitamab (tST001) at doses ranging from 1 to 8 mg/kg Q3W in the dose escalation and 49 patients at 6 mg/kg in the dose expansion. The median follow-up was 195 days. 41 out of 49 patients in the dose expansion at 6mg/kg had CLDN18.2 positive tumor (High: n=9, Medium: n=13, Low: n=19), 8 patients didn't get their tumor tested (unknown CLDN18.2 expression). The baseline demographics of this dose expansion are similar to that of the overall population published on 2023 ASCO (abstract 4046). Osemitamab (tST001) was generated using Transcenta's Immune Tolerance Breaking Technology (IMTB) platform. Osemitamab (SST001) 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. Clinical trials for Osemitamab (TST001) are ongoing in the U.S. and China
(NCT05190575, NCT04396821, NCT04495296, NCT05608785 /CTR20201281). Osemitamab (TST001) was 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.