Conventional biopsy and surgical tumor resection are invasive procedures that capture only one instance of the progression of the tumor. However, the genome of tumor is not static, but it is constantly altered during treatment.

Liquid biopsy is a non-invasive approach based on the extraction of information through peripheral blood analysis. It makes it possible to characterize the development of a solid tumor in real time, through detailed molecular analysis of circulating genetic material in peripheral blood.

Conventional biopsy and surgical tumor resection are invasive procedures that capture only one instance of the progression of the tumor. However, the genome of tumor is not static, but it is constantly altered during treatment.

Liquid biopsy is a non-invasive approach based on the extraction of information through peripheral blood analysis. It makes it possible to characterize the development of a solid tumor in real time, through detailed molecular analysis of circulating genetic material in peripheral blood.

Study procedure:

1. Initial Visit (V0-Baseline): For the purposes of the study the following information will be collected: the demographics, medical and social history, the characteristics of the disease (stage, molecular characterization e.t.c) and the treatment regimen that is followed. As part of the visit, 20 mL of peripheral blood will be drawn prior to their treatment according to physician's suggestion as per common clinical practice. Blood samples will be then sent to ACTC laboratory for plasma/CTC isolation, DNA and RNA extraction and subsequent test for biomarkers. Primary tumor tissue samples will be also collected.

2. Follow-up visit (V1): All patients will provide a 10 mL peripheral blood sample during their planned visit at the end of a series of immunotherapy cycles as per clinical practice and physician's judgment. More specifically:

   For HNSCC/NSCLC: at the end of four (4) treatment cycles with nivolumab (2 months) or at the end of three (3) treatment cycles with pembrolizumab (2 months) or on disease progress (PD) For melanoma: at 6 months after treatment initiation (antiPD-1) Blood samples will be then sent to laboratory for plasma/CTC isolation, DNA and RNA extraction and subsequent test for biomarkers. Clinical response (CR, PR, SD, PD) will be also documented.

3. Follow-up visit (V2): All patients will provide a 10 mL peripheral blood sample on progress of the disease or at the end of the observation period, as diagnosed during their planned visit as per clinical practice and physician's judgment. Blood samples will be then sent to laboratory

Inclusion Criteria:

1. Male or female aged ≥ 18 years of age.

2. Patients with a diagnosis of

   1. recurrent or metastatic head and neck squamous cell carcinoma (HNSCC), who are going to receive PD-1 inhibitor nivolumab OR
   2. metastatic Non-Small Cell Lung Cancer (NSCLC), who are going to receive PD-1 inhibitor, e.g. nivolumab, pembrolizumab,OR
   3. metastatic melanoma, who are going to receive to receive PD-1 inhibitor, e.g. nivolumab, pembrolizumab.

3. Available tumor tissue sample for immunohistochemical and molecular analysis.

4. Life expectancy ≥ 4 months.

5. Signed informed consent form.

Exclusion Criteria:

1. Male or female younger than 18 years old.
2. History of another malignancy within 3 years or current 2nd primary malignancy.
3. Patients that have not signed the informed consent.

155 subjects as follows: 25 patients with metastatic/recurrent HNSCC 120 patients with metastatic NSCLC 10 patients with metastatic melanoma 30 healthy subjects