• Confirmed diagnosis of one of the following:

∙ Relapsed/refractory Acute Myelogenous Leukemia (AML) where no alternative life prolonging therapy exists. Adverse genetic risk treatment naïve patients may also be considered eligible if, in the opinion of the investigator, these patients are unlikely to benefit from alternative therapy (e.g., an older patient with adverse risk MDS who progresses to AML after failing treatment for MDS (i.e. hypomethylating agent (HMA) or HMA and Venetoclax and is not a candidate for traditional AML induction chemotherapy).

‣ Relapsed/refractory Myelodysplastic Syndrome (MDS) those who fail to achieve a complete remission (CR) with at least 4 cycles of HMA (e.g. decitabine or azacitidine); or those who have progressive disease or have intolerance of HMA therapy after at least 2 cycles. Intolerance to HMA includes those patients forced to stop the HMA after at least 2 cycles due to severe infections/worsening cytopenias and are otherwise considered eligible. Patients with MDS have to have intermediate, high, or very high risk disease by International Prognostic Scoring System - Revised (IPSS-R score).

• Adult male or female patients 18 years of age or older.

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1 or 2.

• Patients must satisfy the following laboratory criteria:

∙ Pre-treatment bone marrow staining must demonstrate expression of the ST2 receptor by IHC (low or high expression is allowed).

‣ Total bilirubin \< 1.5 x greater upper limit of normal (UNL). Elevated indirect bilirubin associated with post-transfusion hemolysis is allowed.

‣ Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) must be \< 3 x UNL

‣ Creatinine \< 2 x UNL or calculated creatinine clearance \> 40 ml/min; or Estimated Glomerular Filtration Rate (eGFR) \<50 according to MDRD (Modification of Diet in Renal Disease) method.

‣ White blood cell count (WBC) \< 25,000/uL before the administration of NEROFE on Cycle 1 Day 1. Use of hydroxyurea to control the level of circulating leukemic blast cell counts is allowed before and during the study.

• Suitable venous access to allow for all study related blood sampling (safety and research).

• Estimated life expectancy, in the judgment of the investigator, which will permit receipt of at least 8 weeks of treatment.

• Voluntary written consent must be given before performance of any study related procedure not part of standard medical care, with the understanding that consent may be withdrawn by the patient at any time without jeopardy to future medical care.

• Female patients who are:

∙ Postmenopausal for at least one year before the screening visit, OR

‣ Surgically sterile, OR

‣ If they are of childbearing potential:

• Agree to practice one highly effective method and one additional effective (barrier) method of contraception, at the same time, form the time of signing the informed consent through 4 months after the last does of study drug (female and male condoms should not be used together), OR Agree to practice true abstinence, when this is in line with the preferred and usual lifestyle of the participant. (Periodic abstinence e.g. calendar, ovulation, symptothermal, postovulation methods; withdrawal; spermicides only; and lactational amenorrhea are not acceptable methods of contraception).

• Male patients even if surgically sterilized (e.g. status post vasectomy), who:

∙ Agree to practice effective barrier contraception during the entire study treatment period and through four months after the last dose of study drug (female and male condoms should not be used together), OR

‣ Agree to practice true abstinence, when this is in line with the preferred and usual lifestyle of the participant. (Periodic abstinence e.g. calendar, ovulation, symptothermal, postovulation methods; withdrawal; spermicides only; and lactational amenorrhea are not acceptable methods of contraception).

⁃ Able to undergo bone marrow examination at screening