This is a multi-cohort proof of concept study involving patients with sarcomas or melanomas. Patient models, both two- and three-dimensional, will be derived from tumour samples. These will then be used to evaluate drug sensitivities ex vivo. Enrolled patients will undergo resections or biopsies as part of standard-of-care, which will be used to generate patient models. Patients will receive standard-of-care systemic treatment. Patient models will also be subjected up to a 14-drug screening panel. The majority of drugs in the respective drug panels has been shown to have activity in the respective cancers and would be used in the standard-of-care setting by treating physicians.