Mabwell (Shanghai) Bioscience Co., Ltd. (SHA: 688062; HKG: 2493) announced that it will present, as an oral report, Phase II clinical data for 9MW2821 – its innovative Nectin‑4‑targeted antibody‑drug conjugate (ADC) – at the 2026 European Society for Medical Oncology (ESMO) Congress, to be held October 23–27, 2026 in Madrid, Spain. The data cover locally advanced or metastatic triple‑negative breast cancer (TNBC) patients previously treated with a topoisomerase I inhibitor payload‑based ADC, a heavily pretreated population with limited options. As of the April 10, 2026 data cutoff, among 60 efficacy‑evaluable patients, 9MW2821 achieved an objective response rate (ORR) of 30.0%, a disease control rate (DCR) of 80.0%, a median progression‑free survival (mPFS) of 3.7 months and a median duration of response (mDOR) of 8.7 months; median overall survival (mOS) is not yet mature, and no new safety signals were observed during this follow‑up.
Presentation Snapshot
| Item | Detail |
|---|---|
| Company | Mabwell (Shanghai) Bioscience Co., Ltd. (SHA: 688062; HKG: 2493) |
| Asset | 9MW2821 – first site‑specific conjugation Nectin‑4‑targeted ADC from Mabwell’s ADC platform |
| Venue | ESMO 2026 Congress, Madrid, Spain (23–27 Oct 2026), oral presentation |
| Study | Phase II clinical trial |
| Population | Locally advanced or metastatic TNBC previously treated with topoisomerase I inhibitor payload‑based ADC |
| Data Cutoff | 10 Apr 2026 |
| Evaluable Patients | 60 |
| Safety | No new safety signals observed during follow‑up |
Clinical Evidence – Phase II in Post‑TOP1i‑ADC TNBC
| Endpoint | Result (9MW2821) |
|---|---|
| Objective Response Rate (ORR) | 30.0 % (n = 60 evaluable) |
| Disease Control Rate (DCR) | 80.0 % |
| Median Progression‑Free Survival (mPFS) | 3.7 months |
| Median Duration of Response (mDOR) | 8.7 months |
| Median Overall Survival (mOS) | Not yet mature |
| Safety | No new safety signals; controllable safety profile |
The study results indicate that 9MW2821 demonstrates a controllable safety profile and positive therapeutic effect in TNBC patients – notably in a population already exposed to topoisomerase I inhibitor payload ADCs, where cross‑resistance is a recognized clinical challenge.
Drug Profile & Mechanism of Action
- Molecule: 9MW2821 – Mabwell’s first site‑specific conjugation ADC targeting Nectin‑4, developed on the company’s proprietary ADC drug development platform.
- Conjugation Technology: Through an intellectual‑property‑owned conjugation linker technology and an optimized ADC conjugation process, the antibody achieves site‑specific modification – a design intended to improve homogeneity and payload control versus stochastic conjugation.
- Mechanism: Upon administration, 9MW2821 binds Nectin‑4 on the tumor cell surface and is internalized; through enzymatic cleavage, it directionally releases its cytotoxic payload, achieving precision tumor killing.
- Payload Class: The TNBC program positions 9MW2821 after failure of topoisomerase I inhibitor payload ADCs, suggesting differentiation in payload and/or bystander pharmacology (payload identity not disclosed in the announcement).
Clinical Development Landscape – Four Phase III Trials, 2,200+ Patients Enrolled
9MW2821 is being developed across urothelial carcinoma (UC), cervical cancer (CC), TNBC and esophageal cancer (EC), with cumulative clinical enrollment exceeding 2,200 patients:
- Four Phase III Key Registrational Trials: Covering UC monotherapy and combination therapy, CC monotherapy, and TNBC (post‑topoisomerase I inhibitor payload ADC) monotherapy.
- Breakthrough Therapy Recognition: The UC monotherapy and combination therapy programs have been successively included in the National Breakthrough Therapy Program list.
- Global Firsts: The CC monotherapy program is the world’s first Nectin‑4‑targeted drug to enter Phase III, and the TNBC program is likewise the world’s first in the same indication to reach this development stage – conferring a prominent competitive position.
- Phase I/II Expansion: TNBC combination therapy, UC perioperative combination therapy and EC monotherapy are in Phase II; EC combination and CC combination are in Phase Ib/II.
- Overseas Footprint: TNBC (post‑topoisomerase I inhibitor payload ADC) monotherapy has entered Phase Ib in the United States.
- 2026 Milestones Ahead: Per the company’s R&D plan, the Phase III trials of UC monotherapy, UC combination therapy and CC monotherapy will conduct interim analyses in 2026, and based on interim data Mabwell expects to hold pre‑NDA meetings with the Center for Drug Evaluation (CDE) of China’s NMPA.
Market Impact & Outlook
- Post‑ADC Sequencing Opportunity: With topoisomerase I inhibitor ADCs now standard in advanced TNBC, an effective next‑line Nectin‑4 ADC addresses a rapidly growing sequencing need – the 80.0% DCR and 8.7‑month mDOR in evaluable patients underline durable activity in this setting.
- First‑Mover Position: Mabwell’s global first‑to‑Phase III status in both Nectin‑4 CC and TNBC programs positions 9MW2821 ahead of same‑target competitors in registration timelines.
- Registration Catalysts: The planned 2026 interim analyses of three Phase III trials and potential pre‑NDA meetings with the CDE represent the next major value inflection points for the asset.
- Global Expansion: The U.S. Phase Ib TNBC program provides an initial bridge toward overseas development of the franchise (further ex‑China plans not disclosed).
Forward‑Looking Statements
This brief contains forward‑looking statements regarding 9MW2821, including the upcoming ESMO 2026 oral presentation, ongoing and planned clinical trials, interim analyses of Phase III studies, potential pre‑NDA meetings and future marketing applications. Whether clinical trial results can support the submission of a marketing application, whether marketing approval will ultimately be obtained, and when such approval may be granted remain uncertain. Investors are advised to note potential investment risks; the company will fulfill its information disclosure obligations in a timely manner in accordance with applicable regulations.-Fineline Info & Tech
