Inclusion Criteria:  Voluntarily provide signed informed consent after review of verbal and written material about the trial and agree to abide with protocol requirements. All study related activities must be carried out after written consent is obtained. Subjects must be ≥18 years of age at the time of signing the ICF (Informed Consent Form). Subjects must have an Eastern Cooperative Oncology Group status of 0 or 1. For MM, subjects must have measurable disease by IMWG (International Myeloma Working Group) 2016 criteria For DLBCL, subjects must have measurable disease by Lugano criteria Females must not be breastfeeding or pregnant at screening Females of childbearing potential must not have had unprotected sexual intercourse while participating in this study Male subjects must have had either a successful vasectomy OR they and their female partner must meet the criteria above ie, not of childbearing potential OR practicing highly effective contraception and use a condom throughout the study period  Exclusion Criteria:  Subjects with plasma cell leukemia defined as a plasma cell count >2000/mm3. Subjects with Waldenstrom's macroglobulinemia or smoldering MM. Subjects who had prior treatment with SETD2 or NSD2 inhibitor. Subjects with active acute or chronic systemic infection requiring systemic treatment, including COVID-19. Has cardiovascular impairment Prolongation of corrected QT interval using Fridericia's formula (QTcF) to > 480 msec or history of long QT syndrome. Known left ventricular ejection fraction (LVEF) < 50% by either echocardiogram (ECHO) or multigated acquisition (MUGA). Prior major surgery within 4 weeks of treatment start. Known hypersensitivity to components of the investigational product. Subjects who have received treatment with any unapproved drug product within 4 weeks prior to screening. Current participation in any other interventional clinical study except for follow up. Subjects with a history of or active malignancy other than disease under study Underlying medical/social conditions that in PI opinion will place the subject in significant risk and affect the interpretation of toxicity and adverse events assessments. Inability to take oral medication or known gastrointestinal (GI) disease, GI procedure or medical condition that could interfere with the oral absorption or tolerance of the study drug