Primary objective To study the relationship between the blood levels of soluble PDL1 and β2-microglobulin measured at the diagnostic stage, and the clinical course of a metastatic solid tumor (non-small cell lung cancer, kidney cancer, or melanoma) treated with a 1st line therapeutic immune checkpoint inhibitor.~The secondary objectives are:~To study the relationship between the blood levels of soluble PDL1 and β2-microglobulin measured during treatment, and the clinical course of a metastatic solid tumor treated with a first-line therapeutic immune checkpoint inhibitor.~To study the correlation between the soluble PDL1 level and the tumor PDL1 level.~To study the correlation between the blood levels of soluble PDL1 and β2-microglobulin.~To study the relationship between the blood levels of soluble PDL1 and β2-microglobulin measured during the treatment, and the tolerance of treatment with immune checkpoint inhibitor in 1st line therapy.
Exploratory interventional study of prognostic serum biomarkers of cancer progression.~Study of the relationship between the blood levels of soluble PDL1 and β2-microglobulin, and the clinical course of a metastatic solid tumor treated with a first-line therapeutic of checkpoint immune inhibitor.