SHANGHAI, April 23, 2026

Mabwell has announced the initiation of a Phase III clinical trial for its proprietary Nectin-4-targeting antibody-drug conjugate (ADC), 9MW2821, for the treatment of triple-negative breast cancer (TNBC). This milestone marks a significant advancement in oncology innovation, as 9MW2821 becomes the world’s first Nectin-4-targeting ADC to enter Phase III development for TNBC, addressing a critical gap in treatment options for patients with advanced disease. The trial represents the fourth pivotal study for this asset, reinforcing Mabwell’s commitment to advancing next-generation targeted cancer therapies across multiple tumor types.

Phase III Trial Targets High Unmet Need in TNBC

The newly initiated study is a randomized, open-label, multicenter Phase III trial designed to evaluate the efficacy and safety of 9MW2821 compared to standard chemotherapy in patients with locally advanced or metastatic TNBC. Eligible participants include those who have previously received taxane-based chemotherapy, immunotherapy, and topoisomerase inhibitor-based ADC treatments, highlighting the focus on heavily pretreated patients with limited therapeutic options.

Currently, topoisomerase inhibitor-based ADCs (TOPi-ADCs) are among the standard treatments for advanced TNBC; however, patients who progress after these therapies are often left with chemotherapy as the only remaining option, underscoring a significant unmet clinical need. By targeting Nectin-4, a protein highly expressed in certain cancer cells, 9MW2821 aims to deliver precision cytotoxic therapy directly to tumors, potentially improving outcomes while minimizing systemic toxicity.

Innovative ADC Platform with Regulatory Momentum

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9MW2821 represents a next-generation antibody-drug conjugate, combining targeted antibody specificity with potent cytotoxic payload delivery, a strategy that has rapidly gained traction in oncology drug development. The therapy has already received Fast Track Designation (FTD) from the U.S. Food and Drug Administration (FDA) for the treatment of Nectin-4-positive TNBC, reflecting its potential to address a serious condition with limited treatment options.

Notably, TNBC is the third cancer indication in which 9MW2821 has advanced to Phase III trials, following urothelial carcinoma and cervical cancer, highlighting its broad therapeutic potential across multiple tumor types. Additionally, the program has expanded internationally, with a U.S.-based clinical study already initiated and the first patient dosed in 2025, supporting a global development strategy aimed at accelerating regulatory approvals and market access.

Rising Global Burden of TNBC Drives Innovation

Triple-negative breast cancer is widely recognized as one of the most aggressive and difficult-to-treat breast cancer subtypes, characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and HER2 expression, which limits the effectiveness of targeted therapies. TNBC accounts for approximately 15–20% of global breast cancer cases and is more commonly diagnosed in younger and premenopausal women, often with poorer prognosis compared to other subtypes.

The global incidence of TNBC continues to rise, increasing from 320,000 cases in 2019 to nearly 365,000 in 2024, with projections indicating continued growth in the coming years. This growing disease burden highlights the urgent need for innovative, targeted treatment approaches that can improve survival and quality of life. The advancement of 9MW2821 into Phase III trials signals a critical step forward in addressing this unmet need, with the potential to redefine the standard of care in advanced TNBC and contribute to the broader evolution of precision oncology and targeted therapeutics.

Source: Mabwell press release