康宁杰瑞JSKN033获CDE同意开展复发或转移性宫颈癌III期临床

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# ALPHAMAB ONCOLOGY 康 寧 傑 瑞 生 物 製 藥

(Incorporated in the Cayman Islands with limited liability)

(Stock Code: 9966)

## VOLUNTARY ANNOUNCEMENT APPROVAL FROM CDE FOR JSKN033 TO INITIATE A PHASE III CLINICAL STUDY FOR THE TREATMENT OF CERVICAL CANCER

This announcement is made by Alphamab Oncology (the “Company”, together with its subsidiaries, the “Group”) on a voluntary basis to inform the shareholders (the “Shareholders”) and potential investors of the Group about the latest business advancement of the Group.

The board (the “Board”) of directors (the “Directors”) of the Company is pleased to announce that JSKN033 (a high-concentration subcutaneous co-formulation consisting of anti-human epidermal growth factor receptor 2 (“HER2”) bispecific antibody-drug conjugate (“ADC(s)”) and programmed death ligand 1 (“PD-L1”) immune checkpoint inhibitor) has received approval from the Center for Drug Evaluation (the “CDE”) of the National Medical Products Administration of China (國家藥品監督管理局) (the “NMPA”) to initiate a phase III clinical study of monotherapy in patients with recurrent or metastatic cervical cancer who have failed platinum-based chemotherapy and PD-1/PD-L1 inhibitor treatment (study number: JSKN033-301).

Globally, cervical cancer is the most common gynecological malignancy by incidence and the fourth leading cause of cancer-related death among women. Patients with locally advanced cervical cancer or high-risk early-stage cervical cancer are susceptible to recurrence and metastasis after treatment, and the five-year survival rate for patients with advanced cervical cancer is below 20%. Immunotherapy in combination with platinum-based doublet chemotherapy, with or without bevacizumab, is recommended by authoritative guidelines in China and overseas as a standard first-line treatment; however, disease progression due to drug resistance still occurs in most patients. For patients with cervical cancer who have failed both first-line platinum-based chemotherapy and PD-1/PD-L1 inhibitor treatment, there are currently no highly effective treatment options other than chemotherapy.

JSKN033-301 is a randomized, controlled, open-label, multicenter phase III clinical study to evaluate the efficacy and safety of JSKN033 compared with physician’s choice of chemotherapy in patients with recurrent or metastatic cervical cancer who have failed platinum-based chemotherapy and PD-1/PD-L1 inhibitor treatment.

#### ABOUT JSKN033

JSKN033 is a global first high-concentration subcutaneous co-formulation with JSKN003, the HER2 bispecific ADC and Envafolimab, the PD-L1 single domain antibody, developed by the Group. JSKN003 is a biparatopic HER2-targeting ADC, of which a topoisomerase I inhibitor is linked to the N glycosylation site of the antibody KN026 (a recombinant humanized anti-HER2 bispecific antibody) via the glycosite-specific conjugation. Envafolimab is a Fc fusion protein consisting of humanized anti-PD-L1 single domain antibody and human Immunoglobulin G1 Fc fragment, which has been approved by the NMPA as the global-first subcutaneous injection PD-L1 inhibitor in November 2021.

JSKN033 combines the benefits of immunotherapy and ADCs while enhancing safety and convenience through subcutaneous administration. Currently, multiple phase II clinical studies are progressing smoothly, including studies of JSKN033 in combination with platinum-based chemotherapy as first-line treatment for advanced cervical cancer and JSKN033 monotherapy as second-line or later treatment for cervical cancer and endometrial cancer. JSKN033 has also received approval from the CDE to initiate a phase III clinical study of JSKN033 monotherapy for the treatment of recurrent or metastatic cervical cancer following failure of platinum-based chemotherapy and PD-1/PD-L1 inhibitor treatment.

#### ABOUT THE COMPANY

The Company is a leading biopharmaceutical company in the PRC with a fully integrated proprietary technology platform in ADCs, bispecific antibodies and multi-functional protein engineering. The Company’s highly differentiated in-house pipeline consists of ADCs, monoclonal antibodies and bispecific antibodies in staggered development status in oncology, including, among others, two products approved for marketing by the NMPA and multiple products in phase III or pivotal clinical trial stages. The Company has developed various technologies and platforms of antibody-based therapies for oncology treatment and expertise in this regard. Benefitting from the proprietary protein engineering platforms and structure-guided molecular modeling expertise, the Company is able to create a new generation of multi-functional biological drug candidates that could potentially benefit patients globally.

Cautionary Statement required by Rule 18A.05 of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited: The Company cannot guarantee that it will be able to develop and/or ultimately market JSKN033 successfully. Shareholders and potential investors of the Company are advised to exercise due care when dealing in the shares of the Company.

By Order of the Board Alphamab Oncology Dr. XU Ting

### Chairman and Executive Director

Hong Kong, August 3, 2026

### As at the date of this announcement, the Board comprises Dr. XU Ting as the chairman of the Board and executive Director and Ms. LIU Yang as executive Director, Mr. CHO Man as non-executive Director, and Mr. WU Dong, Ms. WONG Yan Ki Angel and Dr. GAO Xiang as independent non-executive Directors.