Additional testing or assessments may be performed as clinically necessary or where required by institutional or local regulations. 9.1 Efficacy Assessments Study evaluations will take place in accordance with the Schedule of Activities in Section 2 . Only data for the procedures and assessments specified in this protocol should be submitted to the Sponsor or designee on a CRF. Additional procedures a nd assessments may be performed as part of standard of care. However, data for these assessments should r emain in the participant’s medical record and should not be provided to the Sponsor or Designee, unless specifically requested from BMS or designee. 9.1.1 Methods of Assessment CT and MRI are essential parts of the work-up to establish recurrence. The following imaging assessments should be performed at prespecified intervals: CT of the chest and CT or MRI of the abdomen, pelvis, and other known/suspected sites of disease. •CT scans should be acquired wi th a slice thickness of 5 mm or less with no intervening gap (continuous). •Should a par ticipant have a contraindication for CT IV contrast, a non-contrast CT of the chest and a contrast-enhanced MRI of the abdomen and pelvis and other known/suspected sites of disease may be obtained. MRIs should be acquired with a slice thickness of 5 mm or less with no gap (continuous). •Every attempt should be made to image each participant using an identical acquisition protocol on the same scanner for all imaging time points. •PET alone will not be considered for the disease assessment. Complementary CT and/or MRI or biopsy must be performed in such cases. −Note: Use of CT component of a PET/CT scanner: Combined mod ality scanni ng, such as with fluorodeoxyglucose (FDG)-PET/CT, is increasingly used in clinical care and is a modality/technology that is in rapid evolution; therefore, the recommendations outlined here may change rather quickly with time. At present, low-dose or attenuation corrections of the CT portions of a combined FDG -PET/CT are of limited use in anatomically based efficacy assessments, and it is, therefore, suggest ed that they should not be substituted for dedicated diagnostic contrast enhanced CT scans for anatomically based RECIST v1.1 (see Appendix 5 ) or PCWG3 (prostate cancer only) (see Appendix 11 ) measurements. However, if a site can document that the CT performed as part of an FDG-PET/CT is of identical dia gnostic quality to a diagnostic CT (with IV and oral contrast), then the CT portion of the FDG-PET/CT can be used for RECIST v1.1 measurements. Note, however, that the FDG-PET portion of the CT introduces additional data that may bias an investigator if it is not routinely or serially performed. Revised Protocol No.: 04 Date: 31-May-2019 99 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS •Histology or cytological evidence of recurrence should be attempted in all cases except for brain metastases. Cytology and/or histology are mandatory to confirm recurrence in solitary or in equivocal lesions, any new lesions occurring in the kidney, and lymph nodes unless the lesion is too small to biopsy or the risk of biopsy is substantial (eg, inter-aortal node with risk of bleed after biopsy because of close proximity to the aorta and inferior vena cava), in which case, the recurrence must be confirmed with a repeat scan 4 weeks later. Disease assessment with CT and/or MRI, as appropriate, will be performed at baseline and approximately Q8W ( ±1 week) during the treatment phase (prior to dosing at Cycles 3, 5 and 7) until progressive disease per RECIST v1.1 (see Appendix 5 ) or PCWG3 (prostate cancer only) (see Appendix 11 ), or until confirmed progre ssive disease for participants treated beyond progression (defined as an additional 10% or greater increase in tumor burden volume from time of initial progression [including all target lesions and new measurable lesions]), or withdrawal from study. Tumor assessments at other time points may be performed if the investigator is concerned about tum or progression. Tumor res ponse will be assessed by the investigator according to RECIST v1.1 (see Appendix 5 ) or PCWG3 (prostate cancer only) (see Appendix 11) for participants with solid tumors. For participants wi th prostate cancer, bone lesions s hould be assessed using Technetium-99m (Tc-99m) based radionuclide bone scans. Anterior and posterior whole body planar images should be acquired.