CD3-PDD

**CD3-PDD** is a preclinical **protease-activatable anti-CD3 Prodrug DARPin** T-cell engager developed by **Molecular Partners** for oncology. It was described as a tumor-selective construct containing a **tumor-associated antigen binder**, a **CD3 binder**, and a linked **anti-idiotypic blocking DARPin** connected through a **protease-cleavable linker**; in the non-cleaved state the blocker masks CD3-mediated T-cell recruitment, and after cleavage by **tumor-associated proteases** in the tumor microenvironment the molecule becomes an active T-cell engager. Publicly described exemplars used a **mouse cross-reactive EGFR binder** as the tumor-targeting arm in preclinical models to demonstrate reduced systemic cytokine release and improved tolerability relative to an unmasked anti-CD3 engager, with reported anti-tumor activity in humanized mouse models. The program appears to have been presented as a technology/platform-style preclinical construct rather than a marketed or clinically named product.

Other names

anti-CD3 Prodrug DARPinanti-CD-3 Prodrug DARPinanti-CD 3 Prodrug DARPin