This limit is set to avoid instances in which the model could recommend adding subjects indefinitely to a specific dose level due to uncertainty in the tolerability profile. •If, for a specific dose level, 6 subjects have been treated and the chance of determining that the dose level to be the “target” dose is > 50%, then the model will suggest to stop and declare the current dose level to be the maximum tolerated dose (MTD). Model-recommended MTD: The MTD is the dose that satisfies the following 3 conditions: 1) The empirical posterior probability that the ‘DLT rate of 16% -< 33%’ is greater than 50%. 2) This probability needs to be the largest among the dose levels that satisfy the EWOC condition (ie, the probability that ‘DLT rate ≥33%’ must be less than 30%). 3) Minimum number of participants (ie, 6) were treated at this dose level. Final MTD: The final recommended MTD in Part A will be based on the recommendation from the BLRM and overall clinical assessment of all available sa fety, PK/pharmacodynamics, and efficacy data. Lower doses of BMS-986226 ma y be tested if none of the planned doses are found to be tolerable. Such decisions will be made after discussion and agreement between the investigators and the BMS Medical Monitor. 2.1 Simulation Parameters One thousand trial simulations will be used for each scenario. All simulations will be run using EAST v6.3.1 software for BLRM model for the BMS-986226 monotherapy. The number of subjects to be treated in each cohort in a specific dose level and the stopping rules used to declare MTD are defined as: •Fixed cohort size: 3 •Probability of overdosing: < 30% •Probability of achieving the target toxicity: > 50% •Maximum number of participants treated: 30 •Minimum number of participants treated at a given dose level in order to declare MTD: 6 •Maximum number of participants at a dose:12 The provisional dose levels for BMS-986226 monotherapy are 25 mg, 80 mg, 200 mg, 400 mg, and 800 mg. Revised Protocol No.: 04 Date: 31-May-2019 206 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS 2.2 Operating Characteristics Section 2.2.1 demonstrates operating characteristics of BLRM for monotherapy. 2.2.1 Operating Characteristics of BLRM for Monotherapy Five scenarios were investig ated by selecting (1) dose-DLT r elationship derived by prior, (2) dose- DLT curve flatter than the on e by the prior; (3) narrow safety window in order to explore how EWOC limits the risk of exposing participants from a toxic dose level, (4) all doses below the target toxicity, and (5) all doses above the target toxicity. Simulations were performed using EAST v6 BLRM which allows dose skipping.