Inclusion Criteria:  Lung cancer (n= 30):  Adult patients Patients who gave its written informed consent to participate to the study Weight at inclusion ≥ 48 kg NSCLC histology only Stage IV according to 8th TNM classification Planned to be treated with immunotherapy (+/- chemotherapy) as a first line treatment in metastatic setting PD-L1 status on primary tumor available at the inclusion Patients affiliated to a social insurance regime  Head and neck cancer (n= 30):  Adult patients Patients who gave its written informed consent to participate to the study Weight at inclusion ≥ 48 kg Recurrent or metastatic epidermoid carcinomas from oral cavity, oropharynx, hypopharynx, larynx (except nasopharynx) Stage IV according to 8th TNM classification Planned to be treated with immunotherapy (+/- chemotherapy) PD-L1 status on primary tumor available at the inclusion Patients affiliated to a social insurance regime  Exclusion Criteria:  History of previous cancers, except for adequately treated non-melanoma skin cancer, curatively treated in-situ cancer of the cervix, treated and with no evidence of disease for ≥ 5 years Patients under tutorship or guardianship Pregnant or breast feeding women Patients under psychiatric care  Exclusion Criteria specific pour head and neck cohort:  - Patients already treated with immunotherapy