• Patients who have given their free and voluntary written consent to participate in this clinical trial.

• Patients must be at least 18 years of age at the time consent is obtained.

• Patients with a confirmed diagnosis of AML according to the WHO classification (2022 edition) by pathological examination at the performing institution conducted as screening test.

• Patients who meet the following definition of relapsed or refractory. Relapse: Patients with any of the following relapse findings after achieving CR, CRh, or CRi.

‣ Myeloblasts \>5%

⁃ Blood blasts reappear in two peripheral blood samples at least one week apart Refractory: Patients who have failed to achieve CR, CRh, or CRi after a sufficient duration of initial intensive chemotherapy or initial treatment with venetoclax or hypomethylating agents.

• Patients who are considered to have no standard treatment with sustained remission, who have failed to complete a potentially curative treatment, who have no treatment with a promising therapeutic effect, or who have refused standard treatment.

• Patients with an ECOG PS of 0 to 2 on screening test.

• Patients with hematopoietic, hepatic, renal, and cardiac function that meet all of the following criteria on screening test.

‣ Hematopoietic capacity

• Neutrophil count greater than 500/mm3 However, even if the neutrophil count is less than 500/mm3, if the principal investigator or sub investigator judges that the neutrophil count is expected to improve, enrollment in this study is acceptable.

⁃ Liver function

• AST within 3.0 times the upper reference limit

∙ ALT within 3.0 times the upper reference limit

∙ T-Bil within 1.5 times the upper limit of the standard

⁃ Kidney function

• Creatinine clearance (Cockcroft-gault formula) equal to or greater than 50 mL/min

• However, even if the creatinine clearance calculated using the above formula is less than 50 mL/min, if the value is equal to or greater than 30 mL/min and the serum creatinine level is within 1.5 times the upper limit of the standard value, enrollment in this study is acceptable

• ・Cardiac function

⁃ LVEF of 50% or more (MUGA or ECHO)

⁃ QTcF \< 450 msec for males and \< 480 msec for females

• Patients who are expected to survive longer than 3 months.

• Patients who agree to use a method of contraception which is available and effective in their country from (e.g., condom use) from signing informed consent form to 7 months after completion of KK2845 administration in women of child-bearing potential (WOCBP), or from the first KK2845 administration to 4 months after completion of KK2845 administration in male. WOCBP patients must show negativity of serum or urine pregnancy test at screening. Administration should be initiated only after confirmation of negativity of pregnancy test performed before the first administration of KK2845 (Cycle 1 Day 1). However, even in the case of patients with negative pregnancy test, if the possibility of pregnancy cannot be ruled out based on a medical interview, patients cannot enrolled in this study.