One of the most significant hurdles found in successfully treating cancer is that cancers acquire resistance to the treatments they are subjected to. Resistance can be mediated by the microenvironment, preexisting in the tumour population or evolve as genetic and epigenetic alterations confer some tumour cells the capacity to survive and proliferate in the presence of the treatment. Mathematical models can help to identify the mechanisms by which tumours become resistant and investigate the best combinations and scheduling of treatments that would hinder the emergence of a resistant tumour. In this mini symposium we aim to bring together some of the leading researchers in the field and learn about how mathematical models, developed in collaboration with cancer researchers and doctors and validated experimentally and clinically, can be used to gain insight on the mechanisms that lead to tumour resistance to therapies.