Study Population: Eligible participants will have advanced solid tumors, including, but not limited to cervical cancer (CC), colorectal cancer (CRC), head and neck squamous cell carcinoma ( HNSCC), melanoma (MEL), non-small cell lung cancer (NSCLC), prostate cancer (PRC), renal cell carcinoma (RCC), triple negative breast cancer (TNBC) and urothelial carcinoma (UCC). There must be histological or cytological confirmation of a malignancy that is advanced (metastatic and/or unresectable) with measureable disease as defined by Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 or Prostate Cancer Working Group 3 (PCWG 3) (prostate only), including at least 1 lesion accessible for biopsy in addition to the target lesion. Revised Protocol No.: 04 Date: 31-May-2019 10 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS Objectives and Endpoints: Objective Endpoint Primary To characterize the safety and tolerability of BMS-986226 administered alone and in combination with nivolumab or ipilimumab in participants with advanced solid tumorsIncidence of AEs, SAEs, AEs meeting protocol defined DLT criteria, AEs leading to discontinuation, and AEs resulting in death. Incidence of clinical laboratory test abnormalities Secondary To explore the preliminary efficacy of BMS-986226 administered alone and in combination with either nivolumab or ipilimumab in participants with advanced solid tumorsORR, median DOR, and PFS rate at 24 weeksa To characterize the PK of BMS-986226 when administered alone and in combination with either nivolumab or ipilimumab in participants with advanced solid tumorsPK parameter estimates of BMS-986226 To characterize the immunogenicity of BMS-986226 when administered alone and in combination with either nivolumab or ipilimumab in participants with advanced solid tumorsIncidence of anti-drug antibodies (ADA) specific for BMS-986226 To monitor target engagement of BMS- 986226 administered alone and in combination with either nivolumab or ipilimumab in participants with advanced solid tumorsSummary measures of changes from baseline (% or absolute change) in cell surface ICOS expression on T cells and ICOS-ligand + B cells Revised Protocol No.: 04 Date: 31-May-2019 11 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS aThese endpoints will be assessed based on RECIST v1.1 or PCWG3 (prostate only) criteria and will be determined based on tumor measurements occurring every 8 weeks ( ±1 week) during the treatment period and at least every 12 weeks ( ±2 week) in the response and survival follow-up periods. For Part A, scans will be collected centrally and may be reviewed by BICR at a later date, or at any time during the study .