MK-4208

A DLT is any of a prespecified list of adverse events (AEs) of a pre-specified severity that occur during Cycle 1 (up to 28 days) if attributed to the study treatment and not attributed to any other clearly identifiable cause. The percentage of participants who experience DLTs will be reported. Each cycle is 28 days.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of trial intervention, whether or not considered related to the trial intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding that is determined to be clinically significant by the investigator), symptom, or disease (new or exacerbated) temporally associated with the use of trial intervention. The number of participants with at least one AE will be reported.

An SAE is defined as any untoward medical occurrence that, at any dose: Results in death; Is life-threatening; Requires in-patient hospitalization or prolongation of existing hospitalization; Results in persistent disability/incapacity; Is a congenital anomaly/birth defect; Other situations determined to be SAEs by the investigator. The number of participants with at least one SAE will be reported.

An AE is any untoward medical occurrence in a participant, temporally associated with the use of trial intervention, whether or not considered related to the trial intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding that is determined to be clinically significant by the investigator), symptom, or disease (new or exacerbated) temporally associated with the use of trial intervention. The number of participants who discontinued study intervention due to an AE will be reported.

The hematologic response will be evaluated by hematology and differential blood count. A CHR is defined by meeting all the following criteria and lasting for at least 4 weeks: Peripheral blood white blood cell count \< 10 × 109/L ; Peripheral blood platelet count \< 450 × 109/L; No immature cells in peripheral blood, such as myelocytes, promyelocytes, blasts and immature cells, and a basophil level \< 5%; No symptoms or signs of the disease under trial, and the palpable splenomegaly has disappeared. The number of participants with a CHR will be reported.

The MR will be evaluated for all participants, and peripheral blood will be collected and tested for breakpoint cluster region::Abelson (BCR::ABL1/ABLIS) using real-time quantitative polymerase chain reaction performed locally and centrally with validated polymerase chain reaction technology that has a sensitivity of at least 4.5 logs. An MR is defined as follows: MR1: BCR::ABL1IS \> 1% to 10%; MR2: BCR::ABL1IS \> 0.1% to 1%; MR3 (MMR): BCR::ABL1IS \> 0.01% to 0.1%; MR4.0: BCR::ABL1IS \> 0.0032% to 0.01%; MR4.5: BCR::ABL1IS \> 0.001% to 0.0032%, MR5: ≤ 0.001%. The number of participants with a MR will be reported.

The number of participants who had best categorical molecular response shift on treatment relative to baseline will be reported.