Mabwell has announced the initiation of a phase-III clinical study of its proprietary Nectin-4-targeting Antibody Drug Conjugate (ADC) (R&D code: 9MW2821) for the treatment of Triple-Negative Breast Cancer (TNBC). 9MW2821 is the world's first Nectin-4 ADC to enter phase-III clinical study for TNBC. This marks the fourth pivotal trial initiated for 9MW2821.

This is a randomised, open-label, controlled, multicenter phase-III clinical study designed to evaluate the efficacy of 9MW2821 compared with investigator's choice of chemotherapy in patients with locally advanced or metastatic TNBC who have previously received taxane-based chemotherapy with or without immunotherapy and an ADC with a topoisomerase inhibitor payload.

Currently, topoisomerase inhibitor-based ADCs (TOPi-ADCs) are among the standard treatment options for patients with advanced TNBC. For TNBC patients who have failed prior TOPi-ADC therapy, treatment remains primarily based on chemotherapy, representing a significant unmet medical need.

9MW2821 is the world's first Nectin-4?targeting ADC to report efficacy data in TNBC. It has received Fast Track Designation (FTD) from the FDA for the treatment of locally advanced or metastatic Nectin-4?positive TNBC.

TNBC is the third tumor type for which 9MW2821 has entered phase-III pivotal trial, following Urothelial Carcinoma (UC) and Cervical Cancer (CC). 9MW2821 has also initiated a clinical study in the US for ADC-treated TNBC, with the first patient dosed in August 2025.