Simulating the Effect of Removing Circulating Tumor Cells (CTCs) from Blood Reveals That Only Implantable Devices Can Significantly Reduce Metastatic Burden of Patients.

Simple Summary: Circulating tumor cells (CTCs) play an important role in the formation of metastases in the body. Various approaches have been proposed to cleanse the blood of these CTCs and thus prevent the formation of metastases. However, the efficiency of non-implantable blood purification devices for CTC removal has not yet been clearly demonstrated. Here, we have attempted to evaluate, with a simple computer simulation, whether the use of a non-implantable device for CTC excision can be effective and lead to a significant reduction in metastases. We show that non-implantable devices for CTC removal are de facto ineffective in terms of reducing metastases due to various factors. The results of this work argue that only implantable devices can successfully deplete metastasis-relevant CTCs and potentially reduce the metastatic burden of cancer patients. Circulating tumor cells (CTCs) are cells that have separated from a solid cancerous lesion and entered the bloodstream. They play a crucial role in driving the metastatic spread to distant organs, which is the leading cause of cancer-related deaths. Various concepts for blood purification devices aiming to remove CTCs from the blood and prevent metastases have been developed. Until now, it is not clear if such devices can indeed reduce new metastasis formation in a significant way. Here, we present a simple theoretical model of CTCs in the bloodstream that can be used to predict a reduction in metastatic burden using an extracorporeal or intracorporeal blood purification device. The model consists of a system of ordinary differential equations that was numerically solved and simulated. Various simulations with different parameter settings of extracorporeal and intracorporeal devices revealed that only devices implanted directly in tumor-draining vessels can reduce the metastatic burden significantly. Even if an extracorporeal device is used permanently, the reduction in metastases is only 82%, while a permanently operating implanted device in the tumor-draining vessel would achieve a reduction of 99.8%. These results are mainly due to the fact that only a small fraction of CTCs reaches peripheral circulation, resulting in a proportionally small amount of purified blood in extracorporeal devices. [ABSTRACT FROM AUTHOR]