Figure 4.

Radioligand therapy interaction with a cancer patient’s (closed) system. There are three ways in which a radioligand interacts with a tumor: (a) spatial interaction may be direct binding of the radioligand to the specific target on tumor or through interaction with tumor microenvironment e.g., vessels; (b) radioligand leads to modulation of tumor microenvironment to immune system and thus contributes to the efficacy of the treatment; and (c) temporal interaction due to differential physical and biological half-life, different rates of internationalization of the receptor–radioligand complex and also through the influence of amount of tumor burden in a patient as it directly influences the pharmacokinetics of the drug.