One approach of antibody as targeted drug delivery is the use of radioimmunoconjugates in which a radionuclide takes the place of the cytotoxic chemical. https://www.creativebiolabs.net/girentuximab-overview.htm

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is currently in its infancy, and major advances based on the design of new ADCs and a better
understanding of how to use them are sure to come.
Retargeting T cells
immunology. The initial step of cell-mediated cytolysis involves the formation of conjugates between T
cells and target cells. After cytotoxic responses, cancer cell will be killed by engagement of receptors and
co-receptors on T cells. To enhance immune rejection of cancer, two broad approaches combining the
specificity of mAbs with the power of T cell immune responses have been explored. Both of these
approaches are designed to retarget large numbers of T cells towards the tumor by bypassing the need
for the T cell receptor to recognize target antigens as processed and expressed by target cell major
histocompatibility complexes (MHCs).
Bispecific antibodies - for engaging T cells or other
immune cells. Bispecific antibody (BsAb) binding
two different epitopes have been used to
cross-link various cells, receptors, and
molecules. Numerous methods for generating
BsAb have been developed, generation of
hybrid hybridoma or quadroma and chemical
and genetic coupling of the Fab. Developments
in the field of bispecific antibodies for
therapeutic applications have therefore been
focused on the selective retargeting of potent
effector cells of the immune system to tumor cells by binding with one arm to a tumor-associated
antigen and with the other arm to a trigger molecule on the effector cell. Effector cells retargeted with
bispecific antibodies include CTLs, NK cells, monocytes, and macrophages, as well as PMNs. The first
clinical validation of BsAb came with the 2009 approval of catumaxomab (Removab, a bispecific IgG
antibody that targets CD3 and epithelial cell adhesion molecule (EPCAM)) for the treatment of malignant
ascites. Additional bispecific antibodies are under development, including some with different structures
that have longer half-lives and that may not require continuous infusion.
Chimeric antigen receptor T cells. CAR (chimeric
antigen receptor) T cells are genetically
modified to respond to target cells expressing a
given antigen, and consist of a mAb variable
region linked to a T cell-activating motif. CAR T
cells are unique among mAb-based treatment
strategies in that the antitumor effect can
expand over time without additional therapy as
the CAR T cells divide and the tumor specificity
of the CAR T cells is passed on to daughter cells. Although they can result in significant toxicity owing to
cytokine storm that occurs as a consequence of massive activation and proliferation of CAR T cells.
Activation and proliferation are induced when CAR T cells come into contact with a large tumor burden.