NKX101, Intravenous Allogeneic CAR NK Cells, in Adults With AML or MDS

Inclusion Criteria: * General: * ECOG performance status ≤2 * Disease related: * For AML subjects: * Previously treated relapsed/refractory AML, including subjects with MRD+ disease * Received at most 3 lines of previous anti-leukemia therapy * For subjects with targetable fms-like tyrosine kinase 3 (FLT3)-mutated or isocitrate dehydrogenase (IDH)1/2 mutated disease, subjects must have received at least 1 prior respective targeted therapy and may receive up to 4 lines of prior therapy * White blood cell count of ≤25 × 10\^9/L * For groups receiving NKX101 after lymphodepletion with fludarabine/cyclophosphamide +/- decitabine: Disease localized to the bone marrow, as evidenced by ≤ 5% peripheral blasts and no evidence of extramedullary disease * For groups receiving NKX101 after lymphodepletion with fludarabine/ cyclophosphamide +/- decitabine, group receiving NKX101 after lymphodepletion with fludarabine/ara-C: Additional subjects with specifically high-risk genetic mutations may be enrolled. High risk genetic mutation per ELN 2022 should be evaluated as per local assay and discussed with the Sponsor prior to study entry * For groups receiving NKX101 after lymphodepletion with fludarabine/cyclophosphamide +/- decitabine, group receiving NKX101 after lymphodepletion with fludarabine/ara-C: Additional subjects who have relapsed following HCT may be enrolled. * For MDS subjects: * Intermediate-, high-, or very high-risk MDS * Previously treated relapsed/refractory MDS * Received at least 1 and at most 3 lines of previous standard anti-MDS therapy * For groups receiving NKX101 after lymphodepletion with fludarabine/ cyclophosphamide +/- decitabine: Additional subjects with specifically high-risk disease may be enrolled. High-risk genetic mutation should be evaluated as per local assay * For group receiving lymphodepletion with fludarabine/cyclophosphamide +/- decitabine and NKX101: Additional subjects who have relapsed following HCT may be enrolled. * Adequate Organ Function * Platelet count ≥30,000/uL (platelet transfusions acceptable) * Other: * Signed informed consent * Agree to use an effective barrier method of birth control Exclusion Criteria: * Disease related: * Acute promyelocytic leukemia with t(15;17) (q22;q12); or abnormal promyelocytic leukemia/retinoic acid receptor alpha (APML-RARA) and AML arising from chronic myelomonocytic leukemia (CMML) * Evidence of leukemic meningitis or known active central nervous system disease * Peripheral leukocytosis with ≥ 20,000 blasts/μL or other evidence of rapidly progressive disease that would preclude subject from completing at least 1 cycle of treatment * Use of any anti-AML/MDS chemotherapeutic or targeted small molecule drug within protocol specified window prior to the first dose of NKX101 * Presence of residual non-hematologic toxicity from prior therapies that has not resolved to ≤ Grade 1 * Any hematopoietic cell transplantation within 16 weeks * Other comorbid conditions and concomitant medications prohibited as per study protocol * Other: * Pregnant or lactating female