This phase II trial investigates how well CPX-351 and ivosidenib work in treating patients with acute myeloid leukemia or high-risk myelodysplastic syndrome that has IDH1 mutation. The safety of this drug combination will also be studied. IDH1 is a type of genetic mutation (change). Chemotherapy drugs, such as CPX-351, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Ivosidenib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. The purpose of this trial is to learn if CPX-351 in combination with ivosidenib can help to control IDH1-mutated acute myeloid leukemia or high-risk myelodysplastic syndrome.

PRIMARY OBJECTIVE:

I. To determine the overall response rate (ORR) including CR, CRh, CRi, MLFS, and PR of the combination of CPX-351 and ivosidenib in IDH1-mutated patients with AML or high-risk MDS

SECONDARY OBJECTIVES:

I. To assess safety of CPX-351 in combination with ivosidenib. II. To determine time to event endpoints including duration of response (DOR), event free survival (EFS) and overall survival (OS).

EXPLORATORY OBJECTIVES:

I. Evaluate minimal residual disease (MRD) using multiparameter flow cytometry, cytogenetics and molecular evaluation.

II. To evaluate molecular and cellular biomarkers that may be predictive of antitumor activity and/or resistance to treatment including evaluation of 2HG, IDH1 and other co-occurring mutations and VAF levels before, during and after treatment.

OUTLINE:

INDUCTION: Patients receive CPX-351 intravenously (IV) over 90 minutes on days 1, 3, and 5, and ivosidenib orally (PO) once daily (QD) on days 1-28. Patients who do not achieve complete remission may receive a second cycle of induction therapy in the absence of disease progression or unacceptable toxicity. Patients achieving complete remission proceed to consolidation.

CONSOLIDATION: Patients receive CPX-351 IV over 90 minutes on days 1 and 3, and ivosidenib PO QD on days 1-28. Treatment repeats every 28 days for up to 2 cycles in the absence of disease progression or unacceptable toxicity.

MAINTENANCE: Patients receive ivosidenib PO QD for up to 2 years in the absence of disease progression or unacceptable toxicity. Patients who are experiencing clinical benefit and who have not experienced excessive toxicity after completion of 2 years of maintenance may be eligible to continue therapy after discussion with the principal investigator.

After completion of study treatment, patients are followed up at 30 days, then monthly for 3 years.

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2
• IDH1-R132 mutated disease status as assessed by local laboratory. 2HG-producing IDH1 variants outside of R132 (i.e. R100) may be eligible after discussion with the principal investigator (PI)
• Treatment naive or relapsed/refractory AML who are eligible for intensive chemotherapy. Patients with high-risk MDS or MPN (defined as International Prognostic Scoring System Revised [IPSS-R] score ≥ 4 or dynamic [D]-IPSS ≥ 3) may also be eligible after discussion with the PI
• Adequate hepatic function (direct bilirubin ≤ 2 x upper limit of normal (ULN), Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) ≤ 3 x ULN unless deemed to be related to underlying leukemia
• Adequate renal function including creatinine clearance ≥ 30 ml/min based on the Cockcroft-Gault equation.
• Willing and able to provide informed consent
• In the absence of rapidly proliferative disease, the interval from prior treatment to time of initiation will be at least 7 days for cytotoxic or non-cytotoxic (immunotherapy) agents.
• Male subjects must agree to refrain from unprotected sex and sperm donation from initial study drug administration until 90 days after the last dose of study drug

Exclusion Criteria:

• Patients who have previously received CPX-351.

• Patients with any concurrent uncontrolled clinically significant medical condition including infection, laboratory abnormality, or psychiatric illness, which could place the patient at unacceptable risk of study treatment.

• The use of other chemotherapeutic agents or anti-leukemic agents is not permitted during study with the following exceptions (1) intrathecal chemotherapy for prophylactic use or for controlled CNS leukemia. (2) use of hydroxyurea, and/or cytarabine (1 or 2 doses; up to 2 g/m2) for patients with rapidly proliferative disease is allowed before the start of study therapy.

• Patients with active graft-versus-host-disease (GVHD) status post stem cell transplant (patients without active GVHD on chronic suppressive immunosuppression and/or phototherapy for chronic skin GVHD are permitted after discussion with the PI).

• Patients with any severe gastrointestinal or metabolic condition which could interfere with the absorption of oral study medications.

• Patients with symptomatic congestive heart failure (NYHA Class III or IV), unstable angina, or an ejection fraction < 45%.

• Patients with prior anthracycline exposure of > 360 mg/m2 daunorubicin (or equivalent), or > 210 mg/m2 daunorubicin (or equivalent) in patients with prior mediastinal radiation.

• QTc interval using Fridericia's formula (QTcF) > 470 msec. A prolonged QTc interval in the setting of right bundle branch block is permitted after discussion with the PI.

• Nursing women, women of childbearing potential (WOCBP) with positive urine or serum pregnancy test, or women of childbearing potential who are not willing to maintain adequate contraception

  a. Appropriate highly effective method(s) of contraception include oral or injectable hormonal birth control, IUD, and double barrier methods (for example a condom in combination with a spermicide).

• Subjects with a known medical history of progressive multifocal leukoencephalopathy (PML).

• Subjects taking strong CYP3A4 inducers are excluded from the study unless they can be transferred to other medications within ≥ 5 half-lives prior to dosing

• Patients with a diagnosis of acute promyelocytic leukemia (APL).

• Unresolved toxicities > grade 1 from prior treatment including chemotherapy, targeted therapy, immunotherapy, experimental agents, radiation, or surgery.