TRANSTHERA-B - VOLUNTARY ANNOUNCEMENT

FIRST PATIENT DOSED IN PHASE II CLINICAL TRIAL OF TINENGOTINIB IN COMBINATION WITH FULVESTRANT FOR THE TREATMENT OF PREVIOUSLY TREATED HR+/HER2 - RELAPSED OR METASTATIC BREAST CANCER

TransThera Sciences (Nanjing), Inc.

藥捷安康 ( 南京 ) 科技股份有限公司 (a joint stock company incorporated in the People's Republic of China with limited liability) (Stock Code: 2617)

VOLUNTARY ANNOUNCEMENT

FIRST PATIENT DOSED IN PHASE II CLINICAL TRIAL OF TINENGOTINIB IN COMBINATION WITH FULVESTRANT FOR THE TREATMENT OF PREVIOUSLY TREATED HR+/HER2 – RELAPSED OR METASTATIC BREAST CANCER

This announcement is made by TransThera Sciences (Nanjing), Inc. (the "Company", together with its subsidiaries, the "Group") on a voluntary basis to inform the shareholders and potential investors of the Company about the latest business advancement of the Group.

The board of directors of the Company (the "Board") is pleased to announce that the first patient has been dosed recently in the phase II clinical trial of the Company's core product Tinengotinib (TT-00420) in combination with Fulvestrant for the treatment of previously treated hormone receptor positive (HR+) and human epidermal growth factor receptor 2 negative or low expression (HER2-) relapsed or metastatic breast cancer.

This is an open-label, multicenter phase II clinical study conducted in China to evaluate the safety, efficacy, and pharmacokinetics of Tinengotinib in combination with Fulvestrant injection for the treatment of patients with previously treated HR+/HER2 – relapsed or metastatic breast cancer.

The primary target population of this trial is patients with HR+/HER2 – recurrent or metastatic breast cancer who have failed prior standard of care of endocrine therapy and CDK4/6 inhibitor treatment, with an aim to explore the clinical application value of Tinengotinib in combination with Fulvestrant therapy, providing a new treatment option for such treatment-resistant breast cancer patients.

Breast cancer is one of the malignant tumors with high incidence among women globally, with the HR+/HER2 – subtype accounting for approximately 70% of all breast cancer cases. Such patients are prone to drug resistance and relapse following standard treatments, and there is an urgent clinical need for new and effective treatment options. Early clinical study results of Tinengotinib monotherapy demonstrated encouraging clinical efficacy in HR+/HER2 – breast cancer patients who have undergone multiple treatments, supporting its further development in combination with endocrine therapy.

ABOUT TINENGOTINIB

Tinengotinib is an internally discovered, NDA stage, innovative multi-target small molecule kinase inhibitor that exerts antitumor effects by targeting tumor cells and improving the tumor microenvironment. Currently, multiple clinical trials of Tinengotinib are ongoing globally, targeting various solid tumors, such as cholangiocarcinoma (CCA), prostate cancer, breast cancer, and liver cancer. It was granted the Priority Review and Approval Procedure and the Breakthrough Therapy Designation (BTD) by the National Medical Products Administration (NMPA) in China, the Orphan Drug Designation (ODD) and Fast Track Designation by the FDA for the treatment of CCA, and the Orphan Drug Designation (ODD) for the treatment of biliary tract cancer by the European Medicines Agency (EMA).

Warning under Rule 18A.08(3) of the Listing Rules: There is no assurance that the relevant products will ultimately be successfully developed and marketed by the Company.

By order of the Board TransThera Sciences (Nanjing), Inc. 藥捷安康(南京)科技股份有限公司 Dr. Frank Wu Chairman and Chief Executive Officer

Hong Kong, March 18, 2026