What is the mechanism of action of enfortumab vedotin?

Mechanism of Action of Enfortumab Vedotin

Enfortumab vedotin is a Nectin-4-directed antibody-drug conjugate (ADC) that delivers the microtubule-disrupting agent monomethyl auristatin E (MMAE) directly to cancer cells, causing cell cycle arrest and apoptosis. 1

Structural Components

Enfortumab vedotin consists of three key elements that work together to achieve targeted cancer cell destruction 1:

• Antibody backbone: A fully human IgG1 kappa monoclonal antibody (AGS-22C3) that specifically recognizes and binds to Nectin-4, an adhesion protein highly expressed on urothelial carcinoma cell surfaces 1

• Cytotoxic payload: Monomethyl auristatin E (MMAE), a potent microtubule-disrupting agent that interferes with cell division 1

• Linker: A protease-cleavable maleimidocaproyl valine-citrulline (vc) linker (SGD-1006) that connects approximately 3.8-4 molecules of MMAE to each antibody molecule via cysteine residues in the antibody's interchain disulfide bonds 1

Mechanism of Cytotoxic Action

The anticancer activity follows a precise sequence of events 1:

1. Targeting and binding: The antibody component selectively binds to Nectin-4-expressing cells on the tumor cell surface 1

2. Internalization: Following binding, the entire ADC-Nectin-4 complex is internalized into the cell 1

3. Payload release: Once inside the cell, proteolytic cleavage of the linker releases MMAE 1

4. Microtubule disruption: The released MMAE disrupts the microtubule network within the cell 1

5. Cell death: Microtubule disruption leads to cell cycle arrest and subsequent apoptosis 1

Immunomodulatory Effects

Beyond direct cytotoxicity, enfortumab vedotin demonstrates important immunologic activity 1:

• Immune upregulation: When combined with PD-1 blocking antibodies like pembrolizumab, enfortumab vedotin results in upregulation of immune function 1

• Enhanced anti-tumor activity: Preclinical studies in syngeneic mouse tumor models expressing Nectin-4 showed increased anti-tumor activity with the combination compared to either agent alone 1

This dual mechanism—direct cytotoxicity plus immune activation—explains the superior clinical outcomes observed with enfortumab vedotin plus pembrolizumab combination therapy in the EV-302/KEYNOTE-39A trial, which demonstrated median overall survival of 31.5 months versus 16.1 months with platinum-based chemotherapy 2.

Clinical Pharmacology Considerations

The exposure-response relationship reveals important safety correlations 1:

• Higher enfortumab vedotin exposure correlates with increased incidence of grade ≥2 peripheral neuropathy and grade ≥3 hyperglycemia 1

• Peak ADC concentrations occur near the end of intravenous infusion, while peak unconjugated MMAE concentrations appear approximately 2 days after dosing 1

• The elimination half-life is 3.6 days for the ADC and 2.6 days for unconjugated MMAE 1