Precision oncology and personalized cancer treatment aim to determine an optimal therapy for each patient. However, translation of results of drug testing performed on patient‐derived tumor samples to the clinic is highly inefficient, partly because these models (e.g. xenografts, tumor tissue slices, and 2D cell cultures) do not sufficiently reflect the heterogeneity and complexity of human tumors. Therefore, there is an urgent need for novel patient-derived tumor models and novel functional testing capable of improving the care of cancer patients through better therapy monitoring, new drug development and rational treatment planning. The main goal of INTERCELLMED is to develop a platform for next-generation chemosensitivity assay producing 3D cell cultures that mimic the complex tumour-stroma interactions while measuring the changes of key analytes that are involved in regulation of crucial physiological mechanisms, such as K+, pH and O2 levels. The first objective of INTERCELLMED is to develop new protocols for synthesis of particles-based optical sensors sensitive to changes of K+, pH and oxygen. The second objective of INTERCELLMED is to create a biocompatible 3D matrix integrating K+, pH and O2 sensing elements and capable to induce formation of tumour-like structures (i.e. tumoroids) by using a rapid, inexpensive and reproducible synthesis method. The third objective is to validate the 3D sensing scaffold systems for pharmacological studies of anticancer therapy, revealing how K+, pH and O2 changes in and around cells correlate with cell response to drugs. The validation is focused on pancreatic cancer that is one of the most heterogeneous cancers, resulting in high resistance to therapy, with a dismal five-year survival rate of only 7 percent. Our approach is very important for the society because the development of a platform for sensing the tumour microenvironment and cell:cell interactions in 3D in vitro patient-derived tumour models is considered a crucial prerequisite for successful personalized drug development and treatment planning.