Used as a linker in antibody-drug conjugates (ADCs), enabling targeted delivery of cytotoxic agents to cancer cells. The Alloc group acts as a protecting group that can be selectively removed under mild conditions, allowing precise control during synthesis. The PAB (para-aminobenzyloxycarbonyl) spacer enables efficient release of the drug payload inside the cell through enzymatic cleavage, enhancing therapeutic efficacy while minimizing off-target effects. Commonly employed in the development of novel anticancer agents where controlled drug activation is critical.