Table 1.

Potential Advantages and Disadvantages of Pretargeted Radioimmunotherapy Systems

Advantages

• Favorable biodistribution and blood clearance

• High therapeutic ratio (high target to-nontarget organ ratio)

• Flexibility with respect to isotope and antigen target

• Multiple effector dosing possible

• Sequential amplification possible

Disadvantages

• Ab constructs may be difficult to manufacture

• Monovalent (to tumor antigen) Ab fragment constructs may decrease tumor residence time

• Tetravalent constructs (e.g., streptavidin) may crosslink antibody–antigens and internalize

• Immunogenicity (e.g., streptavidin)

• Hapten release from processed Ab may poison tumor-associated conjugate

• Perceived as complex with respect to dosing and timing

• Rapidly internalized antigens are nontargetable

Ab, antibody.