ALT-801-activated Natural Killer Cells After FLAG Induction for Acute Myeloid Leukemia

Hematopoietic stem cell transplantation (SCT) is an effective treatment for acute myeloid
leukemia (AML) and myelodysplastic syndrome (MDS). For patients transplanted in first
remission or with low risk MDS, approximately 60% of patients have achieved long-term
disease free survival. Patients with relapsed leukemia have a poorer outcome; the long-term
disease free survival rate for relapsed AML is 5-10% without hematopoietic stem cell
transplantation (HSCT). With HSCT, survival after relapse approaches 40%, but success
depends greatly on whether patients are in remission at the time of transplant. Many
relapsed patients have refractory chemoresistant disease and never attain remission to be
eligible for potentially curative HSCT, or develop significant complicating comorbidities
during the prolonged intensive reinduction of their disease. Thus, improved strategies for
achieving remission in relapsed patients prior to transplantation are critical to improving
the survival of these patients. Relapsed/refractory AML requires remission prior to
allogeneic HSCT for optimal survival, but responds poorly to chemotherapy. Human leukocyte
antigen (HLA)-haploidentical, NK-enriched peripheral blood cell infusions may augment
induction chemotherapy in patients with poor prognosis AML, but there are significant
toxicities related to the IL-2 infusions given for optimal NK cell activity. The purpose of
this trial is to estimate the toxicity and feasibility of treating relapsed/refractory AML
with FLAG chemotherapy followed by haploidentical donor-derived natural killer (NK) cells
using ALT-801 for ex vivo and in vivo NK cell activation as an alternative to interleukin-2
(IL-2).

ALT-801 is a genetically engineered fusion protein, that is, a single protein made by
combining the DNA of two or more different genes. ALT-801 is a combination of IL-2 (an
important protein for stimulating immune cells) and a binding portion that recognizes tumor
cells.

The primary objective of this study is to evaluate the safety and feasibility of an infused
allogeneic donor NK cell product and ALT-801 following a FLAG preparative regimen to treat
relapsed/refractory acute myelogenous leukemia. The primary endpoint for toxicity is the
absence of NK cell Product or ALT-801-related grade 2 toxicity, excluding grade 2 fever,
rigor/chills, fatigue, vomiting/nausea, pruritus/itching, electrolyte imbalance,
hypoalbuminemia or lymphopenia within 21 days of the ALT-801 or NK cell product infusion.
The primary endpoint of feasibility is defined as being able to infuse NK-cells at the
maximum tolerated cell dose or the highest dose level on day 0 and complete all 8 planned
doses of ALT-801, with a safety that does not exceed toxicity limits, in greater than or
equal to 7 of 10 subjects.

Recipient Inclusion Criteria:

1. Patients with relapsed AML, including those with CNS disease or previous
hematopoietic stem cell transplantation, or primary refractory AML (primary AML that
has failed remission to at least two cycles of induction therapy)

2. For patients of Cohorts 2 to 4, availability of a haploidentical family peripheral
blood stem cell donor selected for best possible KIR reactivity

3. Patient is between 2 and 59 years of age, inclusive

4. Patient must have recovered from the treatment-related toxicities of prior cytotoxic
agents received in the 4 weeks prior to beginning treatment on this protocol, with
the exception of cytopenias resulting from persistent disease, and alopecia

5. Zubrod performance scale (Refer to Appendix C) ≤ 2 or Lansky (Refer to Appendix D) >
60

6. Adequate renal function defined as:

- For adults serum creatinine < 2 mg/dL

- For children serum creatinine < 2 mg/dL or < 2 times upper limit of normal (ULN)
for age (which ever is less) If abnormal creatinine level, 24h creatinine
clearance > 60 mL/min/1.73m^2

7. Adequate liver function, defined as: Total bilirubin ≤ 2 mg/dL and SGPT (ALT) ≤ 2.5 x
ULN for age (unless Gilbert's disease or abnormal liver function due to primary
disease)

8. Pulmonary symptoms controlled by medication and pulse oximetry> 92% room air

9. New York Heart Association classification < III

10. Negative serum test to rule out pregnancy within 2 weeks prior to registration in
females of childbearing potential (non childbearing potential defined as
premenarchal, greater than one year post-menopausal, or surgically sterilized)

11. Sexually active males and females of childbearing potential must agree to use a form
of contraception considered effective and medically acceptable by the Investigator

12. Negative serology for human immunodeficiency virus (HIV)

Recipient Exclusion Criteria:

1. Investigational therapies in the 4 weeks prior to beginning treatment on this
protocol

2. Congestive heart failure < 6 months prior to screening

3. Unstable angina pectoris < 6 months prior to screening

4. Myocardial infarction < 6 months prior to screening

Donor Inclusion Criteria:

1. Related to recipient (sibling, parent, offspring, offspring of a sibling)

2. HLA-haploidentical to recipient (need not be re-tested if already performed
previously, provided copies of the original results are available)

3. Able and willing to undergo apheresis

4. Willing to donate blood for baseline chimerism assessment

5. Negative serum test to rule out pregnancy within two weeks prior to registration in
females of childbearing potential (non childbearing potential defined as
premenarchal, greater than one year post-menopausal, or surgically sterilized)

6. Donor must meet institutional eligibility criteria for allogeneic blood stem cell
donation including infectious disease screening panel (Hepatitis B, Hepatitis C, HIV,
CMV, and West Nile Virus) and CBC, differential and platelet studies

7. Donor must meet stem cell donor eligibility criteria as set forth in 21 CFR 1271
subpart C

8. The preferred Donor will be selected as the most alloreactive of the available
haploidentical related donors on the basis of predicted NK cell alloreactivity using
Recipient and Donor HLA type. If necessary, the best of equally alloreactive donors
will be determined by Donor KIR type. NK alloreactivity is defined as o A KIR gene
is present on the Donor NK cells for which

- the HLA haplotype (KIR ligand) for the KIR receptor in question is absent in the
Recipient, and

- the HLA haplotype (KIR ligand) for the KIR receptor in question is present in
the Donor

Donor Exclusion Criteria:

1. Active infection (defined as on antimicrobial therapy and/or febrile)

2. Pregnant females

3. Breast-feeding females