The study is to conduct a Phase I dose escalation study in order to evaluate the safety and clinical activity of a combined treatment associating an anti-CSF1R (PEXIDARTINIB) with an anti-PD-L1 (DURVALUMAB) in patients with advanced/metastatic colorectal or pancreatic cancers. Dose escalation part will determine the Maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of Pexidartinib given in combination with Durvalumab. Extension part will evaluate the clinical activity of the combination at the RP2D. This evidence concerns the gene CSF1R and familial pancreatic carcinoma.