Biomarker Development for Response Prediction by DNA Mutational Analysis

Inclusion Criteria: 1. Patients with a metastatic solid tumor who have failed at least one line of palliative chemotherapy and are irinotecan naïve. 2. Patients who are, as per local protocol, eligible for palliative treatment with (standard of care) irinotecan. 3. Measurable metastatic lesion(s), according to RECIST 1.1 criteria. 4. Radiological measurable metastatic lesion(s) of which a histological biopsy can safely be obtained: 1. Patients with safely accessible metastases. 2. Patients not known with bleeding disorders (such as hemophilia) or bleeding complications from biopsies, dental procedures or surgeries. 3. Patients not using any anti-coagulant medication at the time of biopsy: all aspirin derivatives, NSAID's, coumarines, platelet function inhibitors, heparins (including LMWHs) and oral factor Xa inhibitors are not allowed, unless medication can either be safely stopped or counteracted. 4. Adequate coagulation status on the day of biopsy as measured by: * PTT \< 1.5 x ULN * APTT \< 1.5 x ULN * Platelet count 100 x 10\*9 / L or higher * PT-INR \< 1.6 * HB \> 6 5. Biopsies should be performed at least four weeks after last bevacizumab administration. 5. Patients age 18 years or up, willing and able to comply with the protocol as judged by the investigator with a signed informed consent. Exclusion Criteria: Patients not meeting all of the above inclusion criteria.