PRINCETON, N.J. and SUZHOU, China, April 29, 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 late-breaking presentation of preclinical study results of novel humanized FGFR2b antibody based ADC (TST105) at AACR Annual Meeting 2025. This ADC, with a novel topoisomerase I inhibitor payload by using glycosyltransferase mediated site-specific conjugation, demonstrated significantly enhanced anti-tumor activity compared to MMAE-based ADCs in preclinical gastric and colorectal tumor models.

Fibroblast growth factor receptor 2 IIIb (FGFR2b), one of the four members of FGFR family that encode transmembrane receptor tyrosine kinases, is overexpressed in a variety of cancers, such as gastric/GEJ (29%)¹, esophageal (41%)², squamous NSCLC (31%)³, TNBC (13%)³, ovarian (40%)³, endometrial (86%)⁴, cervical (80%)⁴, colorectal (62%)⁵, and cholangiocarcinoma (22%)³.

Significant internalization, specific killing activity and bystander killing effect were observed in vitro. TST105 also shows outstanding in vivo tumor killing efficacy in gastric and colorectal tumor models, which may be contributed by the site-specific conjugation.

In vitro studies demonstrated that TST105 induced specific cytotoxicity to gastric and colorectal tumor cells with a potency between 0.3 nM and 0.4 nM, thus expressing higher potent bystander effect than MMAE based ADCs.

In vivo pharmacology study revealed that TST105 exhibited more potent anti-tumor activity than Bema-MMAE in a gastric tumor model. At 3 mg/kg, the tumor growth inhibition (TGI)% were: TST105 91.25%, Bema-MMAE 48.32% on Day 30. The overall response rate (ORR, 50% reduction of tumor volume from baseline) at 3mg/kg for TST105 was 70%, while the ORR for Bema-MMAE was 0%.

Similarly, in a colorectal cancer model, TST105 induced a better anti-tumor efficacy than 38D4-MMAE. At 5 mg/kg the tumor growth inhibition (TGI)% were: TST105 57.43%, 38D4-MMAE 1.92% on Day 30.

“We are highly encouraged by the preclinical profile of TST105, our next-generation FGFR2b-targeted ADC, which combines a novel topoisomerase I inhibitor payload with site-specific conjugation technology. The data presented at AACR underscore its transformative potential in addressing cancers with high FGFR2b overexpression.” said Dr. Yi Gu, senior vice president of Transcenta’s Research Department, “As we advance TST105 into clinical development, We are committed to translating this promising candidate into a transformative therapy for patients globally.”

AACR 2025 held from April 25-30, in Chicago, USA. It is the critical driver of progress against cancer, the place where scientists, clinicians, other health care professionals, survivors, patients, and advocates gather to share and discuss the latest breakthroughs. From population science and prevention; to cancer biology, translational, and clinical studies; to survivorship and advocacy; the AACR Annual Meeting showcases cutting-edge cancer science and medicine.

Reference:

[1] Based on the 910 patients screened for potential participation in the FIGHT Phase 2 clinical trial of bemarituzumab.

[2] Yoshino et al Int J Oncol 2007.

[3] Based on IHC staining conducted by Five Prime and Ventana of commercially sourced tissue samples.

[4] Kurban et al Oncol Rep 2004.

[5] Yoshino et al Oncol Rep 2005.

 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, US and Europe. Transcenta is developing 15 therapeutic antibody molecules for oncology and selected non-oncology indications including bone and kidney disorders.