In doing so, this targeted approach enables the selective destruction of those cells expressing the target antigen, the immunogenic signature of a given tumor cell type. Furthermore, higher doses of the cytotoxic drug can be delivered to the aberrant cells because they don't accumulate peripherally and induce systemic toxicity as they accumulate. Nevertheless, sufficient quantities of the prodrug must be effectively targeted to the tumor cells and converted into an active drug for the cytotoxic effect to be achieved. Bind and bomb. Transition to catalysis.
Researchers allow the unbound antibody to clear and then administer the prodrug.
The enzyme part of the conjugate then cleaves the prodrug to unleash the active form of the drug at the tumor site. Not all tumor cells need be targeted, because activated drug accumulates and diffuses at the tumor site, killing nearby cells. The problem is to identify an enzyme not already present in humans. Using such an enzyme results in the nonspecific activation of the prodrug at peripheral sites as well as near the desired target. To overcome this pitfall, nonhuman enzymes, such as those found in bacteria, have been used.