Predictive Value of Drug Sensitivity Testing Tumorspheres From Patients With Metastatic Colorectal Cancer

Inclusion Criteria: * Metastatic colorectal cancer * Biopsy proven adenocarcinoma compatible with colorectal origin (primary tumor or metastasis) * If only biopsy from metastasis can be obtained, the patient must have a previously resected or image proven tumor of the colon or rectum (scanning or endoscopy) * Non-resectable metastatic spread * Previously exposed to or intolerance or contraindications to standard systemic therapy, defined as * oxaliplatin * irinotecan * 5-fluorouracil (or similar such as capecitabine, S1) * VEGF inhibitor bevacizumab * EGFR inhibitor panitumumab or cetuximab (if RAS/RAF wt) * Progressive disease defined as progression according to RECIST 1.1 * ECOG performance status 0-2 * Age at least 18 years * Adequate bone marrow, liver and renal function allowing systemic chemotherapy * Absolute neutrophil count ≥1.5x10\^9/l and thrombocytes ≥ 100x10\^9/l. * Bilirubin ≤ 1.5 x upper normal value and alanine aminotransferase ≤ 3 x upper normal value * Calculated or measured renal glomerular filtration rate at least 30 mL/min * Anticonception for fertile women and for male patients with a fertile partner. Intrauterine device, vasectomy of a female subject's male partner or hormonal contraceptive are acceptable * Written and orally informed consent Exclusion Criteria: * Incapacity, frailty, disability, or comorbidity to a degree that according to the investigator is not compatible with participation in the protocol * Other active malignant disease requiring therapy * Other systemic anti-cancer therapy (palliative radiotherapy is allowed). * Pregnant (positive pregnancy test) or breast feeding women