Creation of a collection of blood samples that will be collected before and then under treatment in patients with digestive adenocarcinoma during the 1st and 2nd metastatic line and which, depending on scientific progress, can be used for research projects aimed at developing tailored patient management strategies.

Digestive cancers account for 30% of all cancers. The most common of these colorectal cancer (CRC) is the third most common cause of cancer in the world.

In the metastatic phase, patients with digestive cancers generally benefit from medical treatment based on cytotoxic chemotherapy, which can be combined with targeted therapy in certain locations. Their use is based on demonstrating a significant improvement in the overall survival of patients.

However, the therapeutic choice and follow-up of these treatments as a the first line treatment and beyond remain difficult given a cruel lack of biomarkers capable of predicting the response to these different molecules upstream but also usable during treatment to evaluate their efficacy or identify the development of secondary resistance mechanisms.

Indeed, the only biomarkers currently validated and used before the initiation of anti-cancer treatment to stratify patients are:

• the search for mutations in Kirsten rat sarcoma viral oncogene homolog (KRAS) and neuroblastoma rat sarcoma viral oncogene (NRAS) oncogenes as predictive factors for non-response to anti-Epidermal Growth Factor receptor (EGFR) in colorectal adenocarcinomas.
• the search for overexpression of the human epidermal growth factor (HER2) receptor to introduce trastuzumab treatment in esophageal adenocarcinomas.

In addition, they are conventionally determined from tumor tissue, which requires an invasive biopsy or surgical sampling that is difficult to repeat over time.

In this context, it seems essential to us to identify new parameters allowing a better personalization of anti-cancer treatments, by favouring blood biomarkers that have the advantage of being evaluated in a minimally invasive manner and therefore be repeated to be able to judge tumor dynamics.

To this end, we propose the creation of a collection of samples that will be collected before and then under treatment in patients with digestive adenocarcinoma in the 1st and 2nd metastatic line and which, depending on scientific progress, can be used for research projects aimed at developing tailored patient management strategies.

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