Inclusion Criteria:

          -  Participants must be diagnosed with either relapsed or refractory CD33+ AML or higher
             risk MDS

          -  Absolute lymphocyte count ≥ 0.2 k/μL.

          -  Karnofsky performance status score ≥60%.

          -  Life expectancy 12 weeks or more from the time of enrollment.

          -  Pretreatment calculated or measured creatinine clearance (absolute value) of ≥ 40
             mL/minute or Cr > 2x upper limit of normal (ULN).

          -  Serum bilirubin ≤ 2.0 mg/dL or total bilirubin ≤ 3.0 x IULN with direct bilirubin
             within normal range in Participants with well documented Gilbert's syndrome or
             hemolysis or who require regular blood transfusions

          -  Alanine aminotransferase (AST) and aspartate aminotransferase (ALT) < 3.0 x IULN.

          -  Ejection fraction measured by echocardiogram (ECHO) or multi gated acquisition scan
             (MUGA) > 45%.

          -  Participant does not require supplemental oxygen or mechanical ventilation AND has an
             oxygen saturation by pulse oximetry of ≥ 92% or higher on room air.

          -  Negative serum pregnancy test.

          -  Participant has a matched bone marrow donor and is otherwise able to receive a bone
             marrow transplant (dose escalation part only)

          -  Participants who have undergone allo-SCT are eligible if they are at least 3 months
             post SCT, have relapsed AML/MDS as defined above, are not on treatment or prophylaxis
             for GVHD for at least 6 weeks before administration of CAR T cells, and have no active
             GVHD.

          -  All Participants must have the ability to understand and willingness to sign a written
             informed consent.

        Exclusion Criteria:

          -  Diagnosis of acute promyelocytic leukemia

          -  Participants with extramedullary disease as their sole site of relapsed AML.

          -  Known central nervous system (CNS) leukemic involvement that is refractory to
             intrathecal chemotherapy and/or cranio-spinal radiation; Participants with a history
             of CNS disease that have been effectively treated to complete remission will be
             eligible.

          -  Prior treatment with investigational CAR-T therapy for any disease.

          -  Participants enrolled in another investigational therapy protocol for AML within 14
             days or 5 half-lives of enrollment, whichever is shorter.

          -  Ongoing uncontrolled serious infection, symptomatic congestive heart failure, unstable
             angina pectoris, uncontrolled cardiac arrhythmia, poorly controlled pulmonary disease
             or psychiatric illness/social situations that would limit compliance with study
             requirements.

          -  Human immunodeficiency virus (HIV) seropositivity, or active hepatitis B or C
             infection based on testing performed within 28 days of enrollment.

          -  Participants requiring agents other than hydroxyurea to control blast counts within 14
             days of study enrollment.

          -  Participants with presence of other active malignancy within 1 year of study entry.

          -  Participants with adequately resected basal or squamous cell carcinoma of the skin, or
             adequately resected carcinoma in situ may enroll irrespective of the time of
             diagnosis.

          -  Pregnant and breastfeeding women.

          -  History of allergic reactions attributed to compounds of similar chemical or
             biological composition to cetuximab (anti-EGFR).

          -  Active autoimmune disease requiring systemic immunosuppressive therapy (i.e. > 10mg of
             prednisone daily or equivalent).

          -  Participants who, in the opinion of the investigator, may not be able to comply with
             the safety monitoring requirements of the study.