Biparatopic HER2-targeting ADC JSKN003 Was Granted Another Breakthrough Therapy Designation for HER2-Positive Advanced Colorectal Cancer

SUZHOU, China, Oct. 20, 2025 /PRNewswire/ -- October 20, 2025- Alphamab Oncology (stock code: 9966.HK) and CSPC Pharmaceutical Group Co., Ltd. ("CSPC") (Stock Code: 1093.HK) jointly announced that biparatopic HER2-targeting antibody-drug conjugate (ADC) JSKN003 has been granted another breakthrough therapy designation by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) for the indication of monotherapy for the treatment of HER2-positive advanced colorectal cancer (CRC) in patients who have failed prior treatments with oxaliplatin, fluorouracil and irinotecan. Previously, JSKN003 had received breakthrough therapy designation from the CDE for platinum-resistant ovarian cancer (PROC) (not restricted by HER2 expression), as well as clinical trial approval from the U.S. Food and Drug Administration (FDA). It has also been granted Orphan Drug Designation by the U.S. FDA for gastric and gastroesophageal junction cancer. This latest designation in colorectal cancer further underscores its clinical value and global development potential across multiple refractory tumor types.

Colorectal cancer is among the most common malignancies worldwide. According to data from the International Agency for Research on Cancer (IARC), there were approximately 1.93 million newly diagnosed cases and about 903,900 deaths attributed to CRC globally in 2022, ranking third in incidence and second in mortality among all cancers. In China, CRC has the second-highest incidence after lung cancer, with over 500,000 new cases annually and a continuing upward trend. There are currently no HER2-targeted therapies approved in China for CRC. For patients with HER2-positive advanced CRC who have failed prior treatments with oxaliplatin, fluorouracil and irinotecan, the median progression-free survival (mPFS) of approved therapies is only 2.0 to 3.7 months, and the median overall survival (mOS) is approximately 7 to 10 months. There remains a significant unmet clinical need within this patient population.

Clinical studies demonstrated that JSKN003 monotherapy exhibited notable efficacy and a favorable safety profile in patients with HER2-positive advanced CRC, showing meaningful clinical advantages over existing therapeutic options. As of June 30, 2025, a total of 33 patients with HER2-positive advanced metastatic CRC, were enrolled and received JSKN003 monotherapy in a phase I (dose escalation and expansion) and phase II (cohort expansion) clinical study in China (JSKN003-102, NCT05744427), with 42.4% of these patients having previously received 3 or more prior lines of antitumor therapy. Among 32 efficacy-evaluable patients , the overall response rate (ORR) was 68.8%, the disease control rate (DCR) was 96.9%. Additionally, among 31 BRAF V600E wild-type patients, the ORR was 71.0%, the DCR was 100%, and median duration of response (DoR) was 9.89 months, the median PFS achieved 11.04 months, with a 9-month PFS rate of 66.6%. In terms of safety, the median follow-up time was 9.26 months. 7 patients experienced Grade 3 or above treatment-related adverse events (TRAEs). There were no TRAEs led to discontinuation or death. Detailed data from the study were presented recently at the 2025 European Society for Medical Oncology Congress (ESMO Congress 2025). By comparison, in a similar patient population, trastuzumab deruxtecan (DS-8201) previously reported an ORR of 37.8%, a PFS of 5.8 months, and Grade 3 or above adverse events in nearly 50% of patients.

JSKN003 is currently being evaluated in multiple Phase II and Phase III clinical studies in China for the treatment of various solid tumors including breast cancer, ovarian cancer, and gastric cancer. This latest breakthrough therapy designation for JSKN003 is expected to further accelerate its development and review processes, with the aim of bringing benefits to more cancer patients sooner.

About JSKN003

JSKN003 is Alphamab Oncology's first bispecific ADC, developed based on HER2-targeting bsAb KN026, and utilizing the proprietary glycan-specific conjugation platform. It binds to two HER2 epitopes on tumor cells and release topoisomerase I inhibitors (TOPIi) through cellular endocytosis, exerting anti-tumor effects. Compared to similar ADCs, JSKN003 demonstrates better serum stability, reduced hematological toxicity, and stronger tumor inhibition and bystander effect, resulting in significantly wider therapeutic window.

Clinical data in heavily pretreated advanced solid tumors have shown high-security profile, with promising efficacy of JSKN003, particularly in platinum-resistant ovarian cancer (PROC), HER2-high/low breast cancer (BC), HER2-positive colorectal cancer (CRC)/ gastric cancer (GC) and other HER2-expressing tumors. JSKN003 was granted breakthrough therapy designation by CDE for platinum-resistant recurrent epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer and HER2-positive advanced colorectal cancer that has failed prior oxaliplatin, fluorouracil, and irinotecan therapy. It has also been granted Orphan Drug Designation (ODD) by the U.S. Food and Drug Administration (FDA) for GC and gastroesophageal junction cancer (GEJ). Three Phase III trials in HER2-low expressing BC, PROC, and HER2-positive BC and multiple Phase II studies are underway.

In September 2024, the Company entered a licensing agreement with JMT-Bio Technology Co., Ltd. ("JMT-Bio"), a wholly-owned subsidiary of CSPC Pharmaceutical Group Co., Ltd. ("CSPC") (stock code: 1093.HK). JMT-Bio was granted the exclusive license and sublicense rights to develop, sell, offer for sale and commercialize JSKN003, for tumor-related indications in mainland China (excluding Hong Kong, Macau or Taiwan). Alphamab retains exclusive production rights for JSKN003.

About Alphamab Oncology

Alphamab Oncology is an innovative biopharmaceutical company focused on oncology. On December 12, 2019, the Company was successfully listed on the Main Board of the Hong Kong Stock Exchange (Stock Code: 9966.HK).

Leveraging proprietary platforms-including single-domain antibodies, bispecific antibodies, glycan-specific conjugation, linker-payloads, dual-payload ADCs, and high-concentration subcutaneous formulations-the Company has built a differentiated and globally competitive pipeline, covering cutting-edge candidates in ADCs, bispecific antibodies, and single-domain antibodies.

One product has received market approval: Envafolimab (KN035, brand name: 恩维达®), the world's first subcutaneously injected PD-(L)1 inhibitor, offering greater convenience and accessibility in cancer treatment. The NMPA has accepted the new drug application for KN026 (Anbenitamab Injection), a HER2 bispecific antibody, for second-line or later HER2-positive gastric cancer. Four bispecific ADC candidates have entered clinical stages, and next-generation ADC pipelines—such as dual-payload ADCs—are advancing rapidly. The Company has established strategic partnerships with organizations including CSPC, ArriVent, and Glenmark, covering both product development and technology platforms.

Our overarching mission is to make cancer manageable and curable by addressing unmet clinical needs in oncology. Alphamab Oncology is continuously dedicated to the development of effective, safe, and globally competitive anti-tumor drugs, delivering China-innovated cancer therapies to benefit patients worldwide.

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SOURCE Alphamab Oncology