A Study for Oral SY-2101 for Participants With Acute Promyelocytic Leukemia

Key Inclusion Criteria: * Participants must have a diagnosis of APL characterized by the presence of the t(15;17) translocation or PML/RARA gene expression via reverse transcription polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), or cytogenetics. Participants with low-risk APL may be eligible for all parts of this study; participants with high-risk APL are only eligible for the single-dose modules if they have completed a treatment regimen that included ATO within 6 months prior to the Screening Visit. * Participants must have received ATO plus ATRA induction therapy and must have received or be eligible and planning to receive consolidation therapy with ATO plus ATRA in alignment with National Comprehensive Cancer Network (NCCN) guidelines for low-risk APL prior to their enrollment in the study; or participants must have completed a treatment regimen that included ATO within 6 months prior to the Screening Visit. * Participants must be able to tolerate full dose ATO per NCCN guidelines. * Participants must be in morphological complete remission (CR) at the end of induction. * Participants must have a serum or high-sensitivity urine pregnancy test (for females of childbearing potential) that is negative at the Screening Visit and immediately prior to initiation of study treatment (first dose of study drug). Key Exclusion Criteria: * Participants who have demonstrated relapse and therefore are not eligible for further consolidation. * Particip…