Inclusion Criteria:

1. Male or female ≥ 18 years old
2. Histological documentation of adenocarcinoma of the colon or rectum, small intestine, pancreas, stomach, bile duct, oesophagus
3. Patient who will receive a first or second line metastatic chemotherapy and/or targeted therapy
4. Informed consent form (ICF) signed

Exclusion Criteria:

1. Male or female < 18 years old
2. Non-adenocarcinoma histological type
3. Patient already undergoing specific treatment (chemotherapy and/or targeted therapy) in 1st or 2nd metastatic line
4. Pregnant and/or breastfeeding woman
5. Patient not affiliated to a social security system
6. Patient whose regular follow-up is impossible for psychological, family, social or geographical reasons
7. Patient who is included in a Phase I-II therapeutic trial modifying usual management and involving additional and specific blood samples