Any toxicities that occur beyond the 4-week DLT period will also be considered in dose-level d ecisions. For the purpose of participant management, any AE that meets DLT criteria ( Section 7.3.2 ), regardless of the cycle in which it occurs, w ill lead to discontinuation of study tr eatment. Participants who discontinue study treatment during the 4-week DLT evaluation period for reasons other than a DLT may be replaced with a new participant at the same dose level. AEs will be graded according to the National Cancer Institute (NCI) Co mmon Terminology Criteria for Adverse Events (CTCAE) v4.0327. Once the safety (during the 4 weeks DLT period) of 2 mg and 8 mg of BMS-986226 has been established in a single, independent participant per dose, Part A will start. Additional participants may be enrolled in the Preliminary Safety Cohorts per dose level as early as 5 days after the first participant is treated at each dose level to gather additional information on the safety, PK, and PD profile. Intra-participant dose escalation is only allowed in the Preliminary Safety Cohorts as follows: •Once the observation period of 4 weeks for 8 m g is completed, pa rticipant(s) treated at 2 mg may be offered the possibility to dose escal ate at 8 mg. •Once the DLT period of 5 weeks for 25 mg is completed, participant(s) treated at 2 mg that escalated to 8 mg or participant(s) treated with 8 mg may be offered the possibility to dose escalate at 25 mg The decision to dose escalate may be allowed in select participants after discussion and agreement with the BMS Medical Monitor/Study Dir ector (or de signee), as long as the par ticipant is tolerating treatment. The decision to treat a participant with addition al cycles of study treatment (up to a maximum of 24 weeks), will be based on safety, tolerability, and tumor assessment Q8W ( ±1 week) prior to dose administration in the next cycle. Revised Protocol No.: 04 Date: 31-May-2019 56 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS Part A Dose escalation decisions in Part A of the study will be guided by Bayesian Logistic Regression Model (BLRM). Each participant will be administered IV dos es of BMS-986226 per the cohort assignment as follows: •25 mg flat dose Q4W in 4-week cycles for up to 24 weeks of study treatment •80 mg flat dose Q4W in 4-week cycles for up to 24 weeks of study treatment •200 mg flat dose Q4W in 4-week cycles for up to 24 weeks of study treatment •400 mg flat dose Q4W in 4-week cycles for up to 24 weeks of study treatment •800 mg flat dose Q4W in 4-week cycles for up to 24 week s of study treatment A sentinel participant will be used for all c ohorts of monotherapy in Part A and combination therapy in Parts B and C. The first participant in each cohort will receive the Cycle 1 Day 1 dose of study treatment and be observed for 5 days before additional participants (ie, Participant 2 onward) in that cohort receive study treatment. The decision to tr eat a participant with additional cycles of study tr eatment (up to a maximum of 24 weeks), will be based on safety, tolerability, and tumor assessment Q8W ( ±1 week) prior to dose administration in the next cycle. Planned dose levels may be modified or intermediate dose levels added guided by the BLRM analysis with consideration of all available safety, PK, and PD data. Once the safety (during the DLT evaluation) of a dose level has been established, additional participants (up to a total of 12) may be added at that dose level to better characterize the safety, PK, and PD profile. Dose Escalation Decisions for Part A The dose-escalation phase of the study will evaluate the safety and tolerability of BMS- 986226 monotherapy based on DLTs using a BLRM model. During the dose-es calation phase, a set of a pproximately 3 participants w ill be treated initially at each specified dose level. Cohort tolerability assessment and subsequent dose recommendation will occur when at least 2 evaluable participants within a cohort have completed a 5-week DLT period. Any toxicities that occur beyond the 5- week DLT period will be accounted for in making dose level decisions and/or dose level modifications. If the potential DLT occurring in the third evaluable participant regarding the specific dose level does not influence the dose recommendation by BLRM, the next dose level may proceed without waiting for the third participant to complete the corresponding DLT observation period after discussion and agreement betw een the Sponsor and investigators. Continuous re-assessment of dose recommendation, by BLRM in the monotherapy escalation phase, will be carried out for each dose level. Planned dose levels for dose escalation are provided in Table 5.1.2.1-1 . Planned dose levels may be modified, or additional intermediate dose levels added, based upon the BLRM Revised Protocol No.: 04 Date: 31-May-2019 57 Approved 5.0 v Approved 1.0 v Clinical Protocol CA021002 BMS-986226 anti-ICOS analysis. Once the safety (during the DLT evaluation) of a monotherapy dose level has been established (Preliminary Safety Cohorts and Part A ), additional participants (up to 12 total) may be added at that dose level to better characterize the safety, PK, and PD profile. Table 5.1.2.1-1: Dose Escalation (Preliminary Safety Cohorts and Part A) Dose Level BMS-986226 1 2 mg (Preliminary Safety Cohorts) 2 8 mg (Preliminary Safety Cohorts) 3 25 mg (Part A) 4 80 mg (Part A) 5 200 mg (Part A) 6 400 mg (Part A) 7 800 mg (Part A) Dose-limiting Toxicities in Part A For the purpose of guiding dose escalation, DLTs will be defined based on the incidence, intensity, and duration of AEs for which no clear alternative cause is identified. The DLT period will be 35 days (5 weeks) in Part A.