Currently, one in four deaths is caused by cancer, mainly as a result of systemic spread and metastatic disease. Despite new drugs, the currently available therapies are effective only in one in four cancer patients.This could be due to the finding that primary tumors and disseminated tumor cells differ considerably in both genotype and phenotype, so that the target cells of therapies cannot be inferred directly from the properties of the primary tumor.
To reduce the time required for development of novel systemic therapies, companion diagnostic tests are thus needed to enable prediction of whether disseminated tumor cells will respond to the treatment.