Inclusion Criteria: Eligible Diseases

          -  Diagnosis of one of the following CD33-expressing myeloid malignancies with greater
             than or equal to 50% CD33+ target cells with no good standard of care treatment
             options including:

          -  High Risk Myelodysplastic Syndromes (MDS) progressive on two or more prior regimens
             and requiring treatment that meets at least one of the following:

               -  IPSS-R High or Very High Risks

               -  WHO Classification: RAEB-1 or RAEB-2

               -  Poor and very-poor risk cytogenetic abnormality as defined by the IPSS-R
                  cytogenetic classifications

               -  WHO Based Prognostic Scoring System (WPSS): High or Very High Risk

          -  Therapy related MDS and not a candidate for induction chemotherapy or had an
             inadequate treatment response after induction chemotherapy.

          -  Refractory or Relapsed Acute Myelogenous Leukemia (AML) meeting at least one of the
             following:

               -  Refractory AML defined as failure to achieve remission after at least 3 induction
                  attempts

                  ** Elderly AML not fit for induction therapy can be enrolled after 2 failed
                  inductions

               -  Relapsed AML

                    -  Not a candidate for hematopoietic stem cell transplant (HSCT), at least one
                       re-induction attempt required

                    -  Prior HSCT relapse beyond 3 months may be included only if off
                       immunosuppression for a minimum of 4 weeks and do not have GVHD

          -  Advanced systemic mastocytosis (defined as mast cell leukemia, aggressive systemic
             mastocytosis, and systemic mastocytosis associated with hematologic neoplasm) may
             enroll without any prior treatment, given there is no standard established therapy.

        Inclusion Criteria: Age, Performance Status, Organ Function, Contraception Use At least 18
        years of age

          -  Karnofsky score ≥ 70%

          -  Adequate organ function within 14 days (30 days for cardiac and pulmonary) of study
             enrollment defined as:

               -  Renal: an estimated glomerular filtration rate ≥ 60 mL/min/1.73 m2

               -  Hepatic: AST, ALT, alkaline phosphatase and total bilirubin within normal range

               -  Pulmonary function: DLCO corrected (ml/min/mm Hg) defined as no more than 5 units
                  below lower limit of normal (CTCAE v5 Grade 1 carbon monoxide diffusing capacity
                  decreased) based on patient's height, weight, and gender as reported by the
                  institutional pulmonary function lab.

               -  Cardiac: Absence of decompensated congestive heart failure, or uncontrolled
                  arrhythmia; left ventricular ejection fraction ≥ 45% by echocardiogram, MUGA or
                  cardiac MRI.

          -  Absolute lymphocyte count (ALC) ≥ 200 cells/mm³ OR absolute circulating CD56+/CD3- NK
             cell count >25 cells/μl within the 14 days prior to start of therapy

          -  Sexually active females of childbearing potential and males with partners of
             child-bearing potential must agree to use adequate birth control during study
             treatment

          -  Participant provides voluntary written consent signed before performance of any
             study-related procedure not part of normal medical care

        Exclusion Criteria

          -  New or progressive pulmonary infiltrates on screening chest x-ray or chest CT scan
             unless cleared for study by Pulmonary. Infiltrates attributed to infection must be
             stable/improving with associated clinical improvement after 1 week of appropriate
             therapy (4 weeks for presumed or documented fungal infections).

          -  Uncontrolled bacterial, fungal or viral infections, known history of HIV

          -  Active Hepatitis B or Hepatitis C (virus detectable by PCR) - chronic asymptomatic
             viral hepatitis is allowed

          -  Other concurrent active cancer within the last year (excluding non-melanoma skin
             cancers)

          -  Severely clinically obese patients, BMI >38

          -  Currently taking any over-the-counter [OTC], vitamin, mineral, or dietary supplement
             within 14 days prior to study drug administration on Day 1 and during study conduct
             that may confound study safety goals (e.g., St. John's wort). Questions should be
             discussed with GT Biopharma.

          -  Pregnant or breast feeding. The effect of GTB-3550 TriKE on the fetus is unknown.
             Females of childbearing potential must have a blood test within 7 days prior to
             enrollment to rule out pregnancy - must be repeated if not within 7 days of treatment
             initiation

          -  History of central nervous system malignancy or symptoms of active CNS disease

          -  A family history of long QT syndrome or with a QTc interval > 480 msec at screening

          -  Currently taking medications known to prolong QT/QTc interval as the potential risk of
             QT/QTc prolongation is unknown in humans.

          -  A candidate for potentially curative therapy, including hematopoietic cell transplant

          -  Unwilling to remain within a 90 minute drive of the study center through at least Day
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