Describe emerging antibody engineering approaches beyond traditional IgG formats.

Next-generation antibody engineering creates novel formats addressing IgG limitations: 1) Antibody fragments - Fab, scFv, VHH (nanobodies from camelids); smaller size enables tissue penetration but shorter half-life. 2) Half-life extended fragments - Fc fusion, albumin binding, PEGylation extend nanobody half-life. 3) Multi-specific formats - trispecifics, tetraspecifics for complex biology (T-cell redirection plus costimulation). 4) Conditional activation - probodies masked until cleaved by tumor proteases; Cytomx platform. 5) Intracellular antibodies - cell-penetrating peptides or mRNA delivery for intracellular targets. 6) Antibody-cytokine fusions (immunocytokines) - target cytokines to tumor microenvironment. 7) Fc-engineered formats - enhanced or silenced effector functions. 8) Multivalent constructs - increased avidity through multiple binding sites. 9) pH-sensitive antibodies - recycling antibodies that release target in endosome and recycle. Each format optimizes for specific therapeutic application.