This is a prospective, double-blind placebo-controlled, multicenter, randomized phase II trial testing the adjuvant immunotherapy with Nivolumab plus Ipilimumab Placebo or Nivolumab plus Ipilimumab versus Double Placebo Control as a post-surgical/post-radiation treatment for stage IV melanoma with no evidence of disease (NED).

This study will allow for direct comparison of the clinical benefit provided by Nivolumab monotherapy or Nivolumab combined with Ipilimumab versus double placebo control. Furthermore, it will also allow for direct comparison of the respective safety profiles of Nivolumab monotherapy or Nivolumab combined with Ipilimumab. Nivolumab monotherapy was chosen as one of the experimental arms because of a favourable risk-benefit ratio assessed in the large Phase 1 study (MDX1106-03/CA209-003). The combination of Nivolumab and Ipilimumab was chosen as an experimental arm because of the preliminary evidence from the Phase 1 study CA209-004 suggesting synergy between Nivolumab and Ipilimumab resulting in a higher frequency of patients with increased tumour burden reduction. Evaluating both Nivolumab monotherapy and the combination of Nivolumab and Ipilimumab will provide clinical data allowing clinicians to select the appropriate treatment for each patient based on their individual risk-benefit ratio.

Inclusion Criteria:

• Stage IV melanoma arising from a primary cutaneous site or metastatic from an unknown primary site with no evidence of disease (NED) after surgery or radiation therapy (conducted within 8 weeks before enrolment)
• Signed written informed consent
• Known BRAF status
• Subjects must be willing and able to comply with scheduled visits, treatment schedule, laboratory testing, and other requirements of the study
• Minimum life expectancy of five years excluding their melanoma diagnosis
• ECOG performance status of 0 or 1
• Tumor tissue from the resected site of disease must be provided for biomarker analyses. In order to be randomized a subject must have a PD-L 1 expression classification (positive (≥ 5% tumor cells expressing PD-L1) or negative (< 5% tumor cells expressing PD-L1)). If an insufficient amount of tumor tissue from the resected site is provided for analysis, acquisition of additional archived tumor tissue (block and/or slides) for the biomarker analyses is required.
• Prior radiotherapy must have been completed at least 2 weeks prior to study drug administration
• Required laboratory values
• Negative pregnancy test for female subjects and effective contraception (Pearl-Index <1) for both male and female subjects if the risk of conception exists

Exclusion Criteria:

• History of primary uveal or mucosal melanoma
• Prior therapy with CTLA4 or PD1 antibodies
• The patient has psychiatric or addictive disorders that may compromise his/her ability to give informed consent or to comply with the trial procedures.
• Lack of availability for clinical follow-up assessments.
• Any immunosuppressive therapy given within the past 30 days prior to study drug administration (excluding physiologic steroid hormone replacement)
• Other malignancies within the past five years requiring treatment except basal or squamous skin carcinomas or carcinoma in situ of the cervix
• Serious cardiac, gastrointestinal, hepatic or pulmonary disease reducing life expectancy to less than five years
• Patients with serious intercurrent illness, requiring hospitalization.
• Other serious illnesses, e.g., serious infections requiring antibiotics or bleeding disorders.
• The patient is known to be positive for Human Immunodeficiency Virus (HIV) or other chronic infections (HBV, HCV) or has another confirmed or suspected immunosuppressive or immunodeficient condition.
• Known hypersensitivity reaction to any of the components of study treatment
• Pregnancy (absence to be confirmed by ß-HCG urinary test, minimum sensitivity 25IU/L or equivalent units of HCG)) or lactation period
• Women of childbearing potential (WOCBP): Refusal or inability to use effective means of contraception (Pearl-Index <1). WOCBP will be instructed to adhere to contraception until 31 weeks after the last dose of investigational product
• Men who are sexually active with WOCBP must use any contraceptive method with a failure rate of less than 1% per year (Pearl-Index <1). Men receiving Nivolumab and who are sexually active with WOCBP will be instructed to adhere to contraception until 31 weeks after the last dose of investigational product
• Known alcohol or drug abuse
• Participation in another clinical study and use of any investigational or non-registered product (drug or vaccine) within the 30 days before registration
• Significant disease or condition which, in the investigator's opinion, would exclude the patient from the study
• Legal incapacity or limited legal capacity