A phase 1/2 multicenter open-label study to investigate treatment of hydroxyurea (HU) in combination with valproic acid (VPA) or 6- mercaptopurine (6-MP) in combination with VPA in patients with acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (HR-MDS) considered unfit for standard chemotherapy- HUVAMER

Prior treatment

• Patients on treatment for AML (any anti-leukemic therapy including investigational agents) or treated less than 2 weeks before inclusion
• Concurrent history of active malignancy in the past six months prior to diagnosis except for: (a) basal and squamous cell carcinoma of the skin (b) in situ carcinoma of the cervix
• Concurrent severe and/or uncontrolled medical condition (e.g. uncontrolled diabetes, infection, hypertension, pulmonary disease et cetera) at the investigators discretion.
• Patients with any serious concomitant medical condition that could, in the opinion of the investigator, compromise participation in the study.
• Current concomitant chemotherapy, radiation therapy, or immunotherapy other than as specified in the protocol.

Other illness

• Known hypersensitivity to study medications or its excipients
• Any psychological, familial, sociological, and geographical condition potentially hampering compliance with the study protocol and follow-up schedule.
• SARS-CoV-2 infection < 7 days or Covid-19-vaccine < 7 days from study onset
• Patients with a history of non-compliance to medical regimens or who are considered unreliable with respect to compliance
• Patients with senile dementia, mental impairment or any other psychiatric disorder that prohibits the patient from understanding and giving informed consent.

Lab values

• Cardiac dysfunction as defined by: (a) myocardial infarction within the last 3 months of study entry, or (b) medical history recorded reduced left ventricular function with an ejection fraction < 40% as measured by MUGA scan or echocardiogram, or (c) congestive heart failure NYHA class IV or (d) unstable angina, or (e) unstable cardiac arrhythmias

• Female or male, age 18 years or older
• Written informed consent
• Patients NOT eligible for standard therapy (ELN 2022 ), defined as HCT-CI ≥ 3
• Patients NOT eligible for standard therapy for other reasons, including patient’s choice of therapy
• Patients with a diagnosis of AML according to ELN 2022 classification, or relapsed / refractory AML, or sAML (MDS-related/ therapy- induced), or high-risk MDS, or acute promyelocytic leukemia not eligible for standard therapy and/or specific therapy
• Adequate renal and hepatic functions unless clearly disease related as indicated by the following laboratory values: (a) Serum creatinine ≤1.5 x ULN; (b) Estimated creatinine clearance ≥40 mL/min (Cockcroft-Gault equation); (c) Hepatic function; i. Serum bilirubin ≤ 1.5 x upper limit of normal (ULN); ii. Aspartate aminotransferase (AST) 1. ≤2.5 × ULN 2. ≤5 × ULN for patients with liver metastases iii. Alanine aminotransferase (ALT) 1. ≤2.5 × ULN 2. ≤5 × ULN for patients with liver metastases iv. Alkaline phosphatase (ALP) 1. ≤2.5 × ULN
• European Cooperative Oncology Group (ECOG) performance status 0, 1 or 2
• Breastfeeding women
• Female patients of childbearing potential must have a negative serum pregnancy test within 3 days prior to taking their first dose of study medication. Male patients and female patients of reproductive potential must agree to practice highly effective methods of contraception (such as hormonal implants, combined oral contraceptives, injectable contraceptives, intrauterine device with hormone spirals, total sexual abstinence, vasectomy) throughout the study and for >3 months after the last dose of study medication. Female patients are considered NOT of childbearing potential if they have a history of surgical sterility or evidence of post-menopausal status defined as any of the following: (a) Natural menopause with last menses >1 year ago (b) Radiation induced oophorectomy with last menses >1 year ago (c) Chemotherapy induced menopause with last menses >1 year ago