Combination of Spartalizumab, mDCF and Radiotherapy in Patients With Metastatic Squamous Cell Anal Carcinoma

"PBMC collection at baseline, after radiotherapy 8 Gy (gray), at 6 months and at 12 months from inclusion: 6 EDTA tubes of 6 ml of peripheral blood mononuclear cell \[PBMC\] will be sent to the central laboratory (Biomonitoring Platform of Besançon, CHRU de Besançon located at Etablissement Français du Sang) at room temperature within 24 hours via an approved carrier for their processing, storage and immunomonitoring analysis. A sending sheet of the samples will be attached to each single sample.~Plasma collection at baseline, after radiotherapy 8 Gy, at 6 months and at 12 months from inclusion: One 6 ml EDTA tube should be frozen in each investigation center for plasma collection.~Plasma for circulating tumoral DNA (ctDNA) collection at baseline, at 2, 6 and 12 months from inclusion: two EDTA tube of 4 ml should be frozen in each investigation center for ctDNA collection."