Critères d'inclusion : 1) Participants must have been diagnosed with stage IIB/C cutaneous melanoma (AJCC Cancer Staging, 8th edition) and have histologically confirmed melanoma that is completely surgically resected with documented negative margins (per local standard) for disease on resected specimens. All melanomas, except ocular and mucosal melanoma, regardless of primary site of disease will be allowed.
2) Complete resection must be performed within 12 weeks prior to randomization.
Participants must have had a negative sentinel lymph node biopsy. Patients in whom a sentinel lymph node biopsy procedure could not be done or a sentinel lymph node was not detected are not eligible.
3) Participants must have disease-free status documented by a complete physical examination (within 14 days) and imaging studies within 4 weeks (28 days) prior to randomization.
Imaging studies must include CT scans of the chest/abdomen/pelvis or CT scan of the chest and MRI scans of the abdomen and pelvis, and all known sites of resected disease (lymph nodes ≥ 15 mm in short axis). Participants with signs and symptoms consistent with brain metastases should have imaging studies done to rule out the presence of brain metastases.
4) Has not been previously treated for melanoma beyond complete surgical resection of the melanoma lesion.
5) Has recovered adequately from toxicity and/or complications from surgery prior to study start.
6) ECOG performance status of 0 or 1 at the time of enrollment
7) Tumor tissue (minimum of 15 unstained slides or 1 FFPE block) from the resected site of disease must be provided to the central lab prior to randomization
Critères de non-inclusion : 1) History of ocular and mucosal melanoma.
2) Participants with active, known, or suspected autoimmune disease. Participants with type I diabetes mellitus, hypothyroidism only requiring hormone replacement, skin disorders (such as vitiligo, psoriasis, or alopecia) not requiring systemic treatment or conditions not expected to recur in the absence of an external trigger are permitted to enroll.
3) Prior malignancy active within the previous 3 years except for locally curable cancers that have been apparently cured, such as basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the prostate, cervix, or breast.
4) Participants with a condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalent) or other immunosuppressive medications within 14 days of randomization. Inhaled or topical steroids, and adrenal replacement steroid doses > 10 mg daily prednisone equivalent, are permitted in the absence of active autoimmune disease.
5) Women who are pregnant or breastfeeding
6) Participants with serious or uncontrolled medical disorder