Actinium
Pharmaceuticals’ Technology |
Background
Cancer cells originate at one site and spread through the body at different
rates. Current therapy relies upon surgical intervention to remove macroscopic
tumors and irradiation of the tumor site with gamma rays to treat the remaining
microscopic tumors. Chemotherapy is used to attack any residual or non-resectable
disease, either at the surgical site or elsewhere in the body. Unfortunately,
such measures rarely eradicate all of the residual disease. Complementary and/or
alternate therapies are urgently needed to eradicate the remaining tumor cells.
Radioimmunotherapy targets therapeutic radiation to cancer cells anywhere in
the
body through the use of monoclonal antibodies. These targeting moieties identify
and deliver the radiation to the tumor cells without causing significant damage
to normal tissues.
While monoclonal antibodies are made to selectively bind onto specific target molecules, they often lack the necessary therapeutic efficacy and the ability to offer a significant advantage over conventional therapies. Efforts to achieve greater therapeutic effects on the basis of antibody constructs, which include conjugates with chemotherapeutic compounds or Beta particles emitting isotopes, have provided encouraging results, but point to the need for a more focused modality for selective cell-kill.
Full realization of the monoclonal antibodies' inherent
benefits could be achieved by combining their specific targeting characteristics
with the extreme
potency and optimal target range of the alpha particle emitting isotopes,
actinium-225 and bismuth-213. These isotopes provide for the required
selectivity and potency
to directly kill its target cells without any dependency on the patient's
immune system or need for a biological conversion into an active compound.