Globally, one in six deaths is caused by cancer. Thereof, 90% is due to metastasis (the spread of the primary tumor to different parts of the body). The first step of metastasis is invasion, in which the cancer cells penetrate and move through nearby tissues. Because our understanding of invasion and metastasis is limited, no drugs have been developed that selectively stop these processes. The majority of anticancer drugs is indeed still targeting tumor growth, although the unmet need for substances countering invasion and metastasis is by far larger. We have identified and patented new compounds that, when added to tumor cells in very low concentrations, dramatically limit their capacity to invade healthy tissues. Based on the currently available evidence, our substances exploit a new yet unknown mechanism related to specific processes in the mutual attachment of tumor cells. The goals of the project are (i) to obtain a thorough understanding of the mechanism of action of these compounds that will contribute new fundamental insights to the biology of metastasis, and (ii) to develop an assay to evaluate the effect of the compounds on the invasive phenotype in a rapid, robust and reproducible model. There is an unmet need for such a tool and it will also be of general use beyond this project.