Exclusion Criteria: 1. Received any prior treatment with monoclonal antibody against Programmed death 1 (PD1), Programmed death ligand 1 (PD-L1) and CTLA-4 (eg, ipilimumab) 2. The last dose of prior chemotherapy or radiation therapy was received less than 2 weeks prior to randomization 3 Currently receiving systemic corticosteroids or other immunosuppressive medications or has a medical condition that requires the chronic use of corticosteroids. 4. Receipt of live attenuated vaccination within 30 days of starting tremelimumab treatment 5. Active, untreated central nervous system (CNS) metastasis (subjects with brain metastases who are identified at screening 6. History of other malignancy unless the subject has been disease-free for at least 3 years. 7. Any unresolved chronic toxicity CTCAE grade ≥2 from previous anticancer therapy at the time of randomization, 8. Major surgical procedure within 30 days of starting