This trial is a translational proof-of-concept, open-label, prospective cohort study of 60 patients aiming to identify the clinical markers and/or biomarkers associated with therapeutic response to immune checkpoints inhibitors, in patients with advanced melanoma.

The study will be conducted on a population of patients treated with anti-PD-1 alone (nivolumab or pembrolizumab) or in combination (nivolumab + ipilimumab) in the context of routine care.

For each included patient, blood samples will be collected at different time points.

If feasible, an optional tumor biopsy specimen will be collected during baseline visit.

All included patients will be followed-up for tumor response and toxicity until Week 12.

After Week 12, survival data (tumor status and/or survival status) will be collected every 3 months until a maximum duration of 1 year from the first study dose.

Inclusion Criteria:

1. Age ≥18 years at the time of study entry.
2. Patient with histologically-proven metastatic and/or unresectable melanoma (stage IIIc-IV, M1a-c as per AJCC 8th edition), including mucosal melanoma, without intracranial active disease.
3. Patient for which a treatment with immune checkpoint inhibitor (nivolumab alone, pembrolizumab alone, nivolumab plus ipilimumab) has been decided.
4. Subjects are included regardless of BRAFV600 mutation status. BRAFV600 mutation status must be documented.
5. Patient must be naïve to immune checkpoint inhibitor treatment for locally advanced and/or metastatic disease (i.e., no prior treatment with ICI and current treatment with ICI not yet started).
6. ECOG Performance status 0-2.
7. Life expectancy of at least 3 months.
8. Patient able to participate and willing to give informed consent prior performance of any study-related procedures and to comply with the study protocol.
9. Patient affiliated to a Social Health Insurance in France.

Exclusion Criteria:

1. Patient pregnant, or breast-feeding.
2. Uveal melanoma.
3. Any condition contraindicated with sampling procedures required by the protocol.
4. Any psychological, familial, geographic or social situation, according to the judgment of investigator, potentially preventing the provision of informed consent or compliance to study procedure.
5. Any current severe or uncontrolled disease, including, but not limited to ongoing or active infection.
6. Patient who has forfeited his/her freedom by administrative or legal award or who is under guardianship.