The p53 Colorectal Cancer Trial

Inclusion Criteria: * Metastatic colorectal cancer patients for whom conventional therapy has failed; defined as 2 lines of chemotherapy including oxaliplatin or irinotecan- containing regimens as well as an EGFR inhibitor if applicable. * Tumor lesion suitable for biopsy * Age \>18 years * Clinically or radiologically measurable tumor deposits according to the RECIST criteria * WHO performance status 0-1 * Radiology studies (CT thorax/abdomen/pelvis) and echo cor and ECG must be performed within 28 days prior to registration. * Before patient registration in the trial, written informed consent must be given according to national and local regulations. * Blood test requirements: Neutrophils \> 1.0 e9/L Platelets \> 75 e9/L Bilirubin \< 20 µmol / L. Serum creatinine \< 1.5 x ULN Exclusion Criteria: * Co-morbidity including, but not limited to, impaired renal-, liver or bone marrow function, that based on the assessment of the treating physician, may preclude the use of cyclophosphamide at actual doses. * Known hypersensitivity to the study drug, its metabolites or any excipients in the infusion solution. * Psychological, familial, sociological or geographical condition(s) potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial * Pregnant or lactating patients cannot be included. * Clinical evidence of serious coagulopathy. Prior arterial/venous thrombosis or embolism does not exclude patients from inclusion, unless patient is considered unfit by study oncologist. * Patient not able to give an informed consent or comply with study regulations as deemed by study investigator.