mAb can be applied as cytotoxic moieties or drug delivery carriers when conjugated to payload including radioactive molecules, cytotoxic small molecules and cellular components of the immune system. https://www.creativebiolabs.net/nanocarriers.htm

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advantage of these conjugates over conventional drugs is that cytotoxic agents (payloads) can be
delivered directly and at higher local concentrations to tumor tissues, without causing damage to normal
cells.
Radioimmunoconjugates. One approach of
antibody as targeted drug delivery is the
use of radioimmunoconjugates in which a
radionuclide takes the place of the
cytotoxic chemical. Two uses of
radioimmunoconjugates are therapeutic
application and imaging for diagnostic
purposes. Experience over the past 26
years has demonstrated that
radioimmunoconjugates directed towards
solid tumors can be useful as diagnostic
agents, but that they have limited therapeutic impact owing to radioresistance of the tumors. Two
radioimmunoconjugates, ibritumomab tiuxetan (murine IgG1k anti-CD20 mAb) and to situmomab
(murine IgG2a anti-CD20 mAb), have been approved by the FDA as therapeutic agents for the treatment
of lymphoma. Ibritumomab tiutexan comes as either a 90
Y (therapeutic) or 111
I (imaging) radioconjugate,
whereas to situmomab-I131 comes only as the 131
I radionuclide (used for both imaging and therapeutic
purposes). Due to the complex logistics of providing radioimmunotherapy and the emergence of a
number of other new therapies for lymphoma that are less complex to deliver, the modality of
radioimmunotherapy to lymphoma has been surprisingly limited to use, despite it has clear clinical
efficacy and limited toxicity. To explore radioimmuncojugate with highly specific delivery of radiation,
novel radioisotopes is discovered and clinical studies are ongoing.
Antibody–drug conjugates. Attaching cytotoxic effector
molecules to an antibody to form an antibody --drug
conjugate (ADC) provides a mechanism for the selective
delivery of the cytotoxic payload to cancer cells via the
specific binding of the antibody moiety to cancer-selective
cell surface molecules.
Instead of protein toxins of recombinant immunotoxins, ADCs use small molecules to reduce
immunogenicity and overcome the limitations of both nonspecifıc cytotoxic drugs and specifıc but often
ineffective mAbs. Drugs used as components of ADCs include potent drugs such as calicheamicin which
binds to the minor groove in DNA and causes strand scission monomethyl auristatin E which blocks
polymerization of tubulin, maitansine which inhibits the assembly of microtubules and, most recently,
pyrroloben zodiazepines which crosslink DNA. The first marketed ADC was gemtuzumab ozogamicin
(Mylotarg; Wyeth/Pfizer), a humanized anti-CD33 IgG4 conjugated to calicheamicin that was approved
for the treatment of acute myeloid leukaemia in 2000. ADCs are complex. The multiple parameters for
optimization include target antigen and epitope, antibody, drug, linker, attachment chemistry and
drug-to-antibody ratio (DAR).The field is rapidly expanding with more than 60 ADCs currently in
development and in clinical trials, and many have shown encouraging preliminary results. The ADC field