HDM201 Added to CT in R/R or Newly Diagnosed AML

Inclusion Criteria:

All Subjects

* Signed informed consent must be obtained prior to participation in the study
* Age ≥18
* Diagnosis of AML based on WHO 2016 classification. Patients with APL (acute promyelocytic leukemia) with PML-RARA are not eligible.
* Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) that is 0 - 2.
* Adequate organ functions
* Left ventricular ejection fraction \> 45%

For 1L AML population:

* For Part 1 or Part 2 Expansion Cohorts 1 or 2: subjects with de novo AML suitable for induction treatment with cytarabine and anthracyclines as per investigator judgement
* For Part 2 Expansion Cohort 2: documented presence of FLT3 mutation (ITD or TKD ) and suitable for midostaurin treatment as per investigator judgement.
* For Part 2 Expansion Cohort 3: Subjects with secondary AML (e.g. AML-MRC , secondary to myelodysplasia/MDS or therapy-related AML). Prior use of hypomethylating agents or other therapies with curative intent for treatment previous hematological malignancies or therapy-related AML is allowed. Subjects suitable for induction treatment with liposomal cytarabine/daunorubicin as per investigator judgement.

For R/R AML population:

* All Parts: Diagnosis of relapsed or refractory AML and suitable for treatment with IDAC as per investigator judgement.
* For Part 3 only: willingness and suitability to participate in DDI Cohort 1 or 2.

Exclusion Criteria:

* Prior exposure to MDM2 and MDM4 inhibitor (e.g. idasanutlin)
* Known symptomatic CNS leukemia not controlled by adequate therapy.
* Isolated extramedullary leukemia
* Subjects with prior malignancy (some exceptions apply)
* QTcF \> 470 ms at screening
* Subjects who require treatment with moderate or strong CYP3A4 inducers within 14 days prior to starting study treatment or during the study
* Subjects who require use of herbal preparations/medications and dietary supplements within 7 days prior to first dose and during the study
* Subjects who require treatment with substrates of CYP3A4/5 with narrow therapeutic index (within 24 hours prior to during and 48 hours after HDM201 administration)
* Subjects who require treatment with moderate or strong CYP3A4 inhibitors within 48 hours prior to, during and 48 hours post HDM201 administration. (except for Part 3 DDI Cohort 1 and 2)
* Subject is pregnant or breastfeeding
* WOCBP unless using highly effective methods of contraception during study treatment and for an appropriate time period after last study treatment
* Sexually active males unless they use a condom during intercourse while taking study drug and for an appropriate time period after last study treatment

For Part 1 only:

\- Subjects with a known favorable risk AML subtype at screening or subjects with FLT3 mutation

For Part 3 only:

* DDI Cohort 1: use of posaconazole (other than the planned dosing required by the protocol) within 7 days prior to start of the DDI investigation and for the duration of the DDI period
* DDI Cohort 2: use of midazolam (other than the planned dosing required by the protocol) within 2 days prior to start of the DDI investigation and for the duration of the DDI period
* DDI Cohort 1 and 2: subjects who have received, or are expected to receive moderate or strong inhibitors of CYP3A4 within 7 days prior to start of the DDI investigation, for the duration of the investigation, and 24 hours after last blood sample collection for PK assessment

Other protocol-defined inclusion/exclusion may apply.