On January 13, 2025, Duality Biologics (Shanghai) Co., Ltd. (“DualityBio”), a client of Fangda, jointly announced a cooperation agreement (the “Agreement”) with Shenyang Sunshine Pharmaceutical Co., Ltd. (“Shenyang Sunshine”), a subsidiary of 3SBio Inc., for a HER2 ADC drug namely DB-1303. Under the Agreement, Shenyang Sunshine will obtain the right to commercialize the HER2 ADC drug namely DB-1303 developed by DualityBio for several indications in mainland China, Hong Kong and Macau. Shenyang Sunshine will pay Duality Biologics a non-refundable upfront of USD 25 million and up to USD 42 million as R&D milestone payments, as well as potential additional sales milestone payments. Meanwhile, Duality Biologics will continue to be responsible for the clinical development, registration and other works in the cooperation regions.

DB-1303 is a next-generation HER2 ADC molecule developed using DualityBio’s Proprietary DITAC platform, with a topoisomerase-1 inhibitor as the cytotoxic payload. HER2 (human epidermal growth factor receptor 2) is a protein expressed on the surface of solid tumors and is associated with aggressive tumor growth and metastasis. DB-1303 targets HER2 receptors and has the potential to kill tumor cells while also exhibiting a bystander killing effect. DB-1303 has shown promising efficacy and safety in patients with various advanced solid tumors, including breast and endometrial cancers. It is currently undergoing a global Phase I/II trial for patients with advanced/metastatic solid tumors and a pivotal Phase III trial for patients with hormone receptor-positive (HR+) and HER2-low expressing metastatic breast cancer. In China, DB-1303 is being studied in a pivotal Phase III trial for patients with HER2-positive unresectable/metastatic breast cancer. The drug has received Fast Track and Breakthrough Therapy designations from the U.S. FDA and Breakthrough Therapy designation from China’s CDE.

DualityBio is a clinical-stage company focused on developing the next-generation ADC therapeutics for patients with cancer and autoimmune diseases. The company has successfully established a number of next generation Antibody-Drug Conjugate (ADC) technology platforms with global intellectual property rights. Building upon deep understanding of disease biology and translational capability, DualityBio has advanced multiple clinical-stage assets into global multi-regional clinical trials across 17 countries, enrolling more than 1,500 patients. Additionally, DualityBio is continuing to develop its novel protein engineering and ADC technology platforms to create the next wave of “Super ADC” molecules including bispecific ADCs, novel MOA payload ADCs and autoimmune ADCs.

3SBio is a leading biopharmaceutical company engaged in the R&D, production, and sales of high-quality medicines aimed at improving patient quality of life and contributing to human health. The company holds over 100 national invention patents and has more than 40 marketed products covering nephrology, oncology, autoimmune diseases, ophthalmology, and dermatology. It operates the National Engineering Research Center for Antibody Drugs and four R&D centers across both biologics and chemical drug platforms, with 28 pipeline products, four production bases, and four CDMO bases.

The Fangda team provided comprehensive legal services to DualityBio in this transaction, including transaction structure design, transaction document preparation, and ancillary document negotiation, revision and finalization. The team was led by partner Josh SHIN, with support from partner Henry HE and counsel Bella WANG. Team members also included Jessica ZHUANG and Essie ZHAO.