Anti-CD22 Chimeric Receptor T Cells in Pediatric and Young Adults With Recurrent or Refractory CD22-expressing B Cell Malignancies

Background:

- Adoptive cellular therapy with T cells genetically modified using viral-basedvectors to
express chimeric antigen receptors targeting the CD19 molecule have demonstrated
dramatic clinical responses in patients with acute lymphoblastic leukemia (ALL).
However, not all patients respond and CD19-negative escape has been observed following
CD19 CAR therapy, as well as anti-CD19/CD3 bispecific antibody therapy. Thus, additional
targets are needed.

- CD22 is a B-lineage-restricted, transmembrane phosphoglycoprotein of the Ig superfamily
that is widely expressed on B-cell malignancies including 96% to 100% of pediatric
Bprecursor ALL. Therefore, CD22 represents a promising target. Encouraging responses
targeting CD22 with an antibody based immunoconjugate have been seen in patients,
including children, with recurrent and refractory ALL. This will be the first in human
testing of anti-CD22 CAR adoptive cell therapy.

Objectives:

- To determine the feasibility of producing anti-CD22 CAR cells meeting established
release criteria. Complete

- To assess the safety of administering escalating doses of anti-CD22-CAR engineered T
cells in children and young adults with recurrent or refractory CD22- expressing B cell
malignancies following a cyclophosphamide/fludarabine preparative regimen.

Eligibility:

- Patients 1-30 years of age, at least 15 kg, with CD22-expressing B-cell malignancies that
have recurred after or not responded to one or more standard regimens and deemed incurable by
standard therapy. Patients with a history of allogeneic hematopoietic transplantation (SCT)
who meet all eligibility criteria are eligible to participate. Patients previously treated
with anti-CD19 CAR engineered T cells are also eligible.

Design:

- PBMC will be obtained by leukapheresis, CD3+ cells enriched and cultured in the presence
of anti-CD3/-CD28 beads followed by lentiviral vector supernatant containing the
anti-CD22 (M971BBz) CAR.

- On Day -4 (cell infusion is Day 0), patients will begin induction chemotherapy
comprising fludarabine 25 mg/m2 on Days -4, -3 and -2 and cyclophosphamide 900 mg/m2 on
day 2.

- The CD22-CAR cells will be infused on Day 0, with up to a 72h delay allowed for infusion
of fresh cells or a 7 day delay if cells are cryopreserved, if needed for resolution of
clinical toxicities, to generate adequate cell numbers, or to facilitate scheduling.

- A phase I cell dose escalation scheme will be performed using 4 dose levels (3 x 105
transduced T cells/kg; 1 x 106 transduced T cells/kg; 3 x 106 transduced T cells/kg; and
1 x 107 transduced T cells/kg ( 20%)). If 2/6 patients have DLT at dose level 1, safety
will be evaluated in a de-escalated dose of 1 x 105 transduced T cells/kg ( 20%)). Once
the maximum tolerated dose (or highest level evaluated) is reached, enrollment into an
expansion cohort of a total of 17 patients at MTD in two strata will proceed to provide
additional information regarding the feasibility, safety and efficacy of this treatment.
Patients who have previously received CD19 CAR T cells will be evaluated separately from
CARna(SqrRoot) ve patients as response may be different in these two groups.

- Patients will be monitored for toxicity, response and T cell persistence as well as
other biologic correlates.

-INCLUSION CRITERIA:

1. Patient must have a B cell ALL (inclusive of ALL blast transformation from CML) or
lymphoma and must have relapsed or refractory disease after at least one standard
chemotherapy regimen and one salvage regimen. In view of the PI and the primary
oncologist, there must be no available alternative curative therapies and subjects
must be either ineligible for allogeneic stem cell transplant (SCT), have refused SCT,
recurred after SCT, or have disease activity that prohibits SCT at the time of
enrollment.

2. CD22 expression must be detected on greater than 15% of the malignant cells by
immunohistochemistry or greater than 80% by flow cytometry. The choice of whether to
use flow cytometry or immunohistochemistry will be determined by what is the most
easily available tissue sample in each patent. In general, immunohistochemistry will
be used for lymph node biopsies, flow cytometry will be used for peripheral blood and
bone marrow samples and CSF when feasible.

3. Patients must have measurable or evaluable disease at the time of enrollment, which
may include any evidence of disease including minimal residual disease detected by
flow cytometry, cytogenetics, or polymerase chain reaction (PCR) analysis.

4. Greater than or equal to 1 year of age (and at least 15 kg) and less than or equal to
30 years of age at time of enrollment. NOTE: The first 3 patients in the first dose
cohort must be greater than or equal to 16 years of age, while the first 2 patients in
subsequent dose cohorts must be greater than or equal to 16 years of age.

5. Subjects with the following CNS status are eligible:

- CNS 1, defined as absence of blasts in cerebral spinal fluid (CSF) on cytospin
preparation, regardless of the number of WBCs;

- CNS 2, defined as presence of < 5/uL WBCs in CSF and cytospin positive for
blasts, or > 5/uL WBCs but negative by Steinherz/Bleyer algorithm:

- CNS 2a: < 10/uL RBCs; < 5/uL WBCs and cytospin positive for blasts;

- CNS 2b: greater than or equal to 10/uL RBCs; < 5/uL WBCs and cytospin
positive for blasts;

- CNS 2c: greater than or equal to 10/uL RBCs; greater than or equal to 5/uL
WBCs and cytospin positive for blasts but negative by Steinherz/Bleyer
algorithm.

6. CNS3 who has failed salvage systemic and intensive IT chemotherapy (and therefore not
eligible for radiation)

7. Patients with isolated CNS relapse will be eligible if they have previously been
treated with cranial radiation (at least 1800 cGy) but only in the absence of
neurologic symptoms suggestive of bulky CNS disease, such as cranial nerve palsy due

to active disease.

8. Patients, parents/guardian(s), legally authorized representative (LAR), or durable
power of attorney must be able to give consent and sign the informed consent document.
Pediatric subjects will be included in age appropriate discussion and verbal assent
will be obtained for those > 7 years of age, when appropriate.

9. Clinical performance status: Patients greater than or equal to 16 years of age:
Karnofsky greater than or equal to 50%; Patients < 16 years of age: Lansky scale
greater than or equal to 50%. Subjects who are unable to walk because of paralysis,
but who are upright in a wheelchair will be considered ambulatory for the purpose of
calculating the performance score.

10. Patients of child-bearing or child-fathering potential must be willing to practice
birth control from the time of enrollment on this study and for four months after
receiving the preparative regimen.

11. Females of child-bearing potential must have a negative pregnancy test because of the
potentially dangerous/unknown effects on the fetus.

12. Cardiac function: Left ventricular ejection fraction greater than or equal to 45% or
fractional shortening greater than or equal to 28%.

12. Patients with history of allogeneic stem cell transplantation are eligible if at least
100 days post-transplant, if there is no evidence of active GVHD and no longer taking
immunosuppressive agents for at least 30 days prior to enrollment.

13. Patients previously treated with anti-CD19 CAR or other adoptive cell therapies will be
eligible if all other eligibility criteria are met but will be evaluated as a separate
strata from CAR-naive patients in the expansion phase. Circulating CAR T cells must be <5%.

EXCLUSION CRITERIA:

Subjects meeting any of the following criteria are not eligible for participation in the
study:

1. Recurrent or refractory ALL limited to isolated testicular or isolated central nervous
system (CNS) disease.

2. Hepatic function: Inadequate liver function defined as total bilirubin > 2 x upper
limit of normal (ULN) (except in the case of subjects with documented Gilbert s
disease > 3 x ULN) or transaminase (ALT and AST) > 5 x ULN based on age- and
laboratory specific normal ranges;

3. Renal function: Greater than age-adjusted normal serum creatinine or a creatinine
clearance < 60 mL/min/1.73 m^2.

- Less than or equal to 5 years old, maximum serum creatinine:0.8 mg/dL

- Less than 5 years old, less than or equal to 10 years old, maximum serum
creatinine:1.0 mg/dL

- Greater than 10 years old, maximum serum creatinine:1.2 mg/dL

4. Hematologic function:

- Absolute neutrophil count (ANC) < 750/uL, or platelet count < 50,000/uL, if these
cytopenias are not judged by the investigator to be due to underlying disease
(i.e. potentially reversible with anti-neoplastic therapy);

- A subject will not be excluded because of pancytopenia greater than or equal to
Grade 3 if it is due to disease, based on the results of bone marrow studies.

5. Subjects with radiologically-detected CNS lymphoma

6. Hyperleukocytosis (greater than or equal 50,000 blasts/uL) or rapidly progressive
disease that in the estimation of the investigator and sponsor would compromise
ability to complete study therapy;

7. Pregnant or breast-feeding females;

8. Recent prior therapy:

9. Systemic chemotherapy less than or equal to 2 weeks (6 weeks for clofarabine or
nitrosoureas) or radiation therapy less than or equal to 3 weeks prior to apheresis;

- Exceptions:

1. There is no time restriction in regard to prior intrathecal chemotherapy
provided there is complete recovery from any acute toxic effects of such;

2. Subjects receiving hydroxyurea may be enrolled provided there has been no
increase in dose for at least 2 weeks prior to starting apheresis;

3. Patients who are on standard ALL maintenance type chemotherapy (vincristine,
6- mercaptopurine or oral methotrexate or a tyrosine kinase inhibitor for
patients with Ph+ ALL) may be enrolled provided that chemotherapy is
discontinued at least 1 week prior to apheresis.

4. Subjects receiving steroids may be enrolled, provided there has been no
increase in dose for at least 1 week prior to starting apheresis;

5. For radiation therapy: Radiation therapy must have been completed at least 3
weeks prior to enrollment, with the exception that there is no time
restriction if the volume of bone marrow treated is less than 10% and also
the subject has measurable/evaluable disease outside the radiation port.

- Other anti-neoplastic investigational agents, or antibody based
therapies currently or within 2 weeks prior to apheresis (i.e. start of
protocol therapy);

- Subjects must have recovered from the acute side effects of their prior
therapy, such that eligibility criteria are met. Cytopenias deemed to
be disease-related and not therapy-related are exempt from this
exclusion.

- Prior CAR therapy within 30 days prior to apheresis or prior CAR
therapy at any time with evidence for persistence of CAR T cells in
blood samples (circulating levels of genetically modified cells of
greater than or equal to 5% by flow cytometry).

10. HIV/HBV/HCV Infection:

1. Seropositive for HIV antibody. (Patients with HIV are at increased risk of lethal
infections when treated with marrow-suppressive therapy. Appropriate studies will
be undertaken in patients receiving combination antiretroviral therapy in the
future should study results indicate effectiveness.)

2. Seropositive for hepatitis C or positive for Hepatitis B surface antigen (HbsAG).

11. Uncontrolled, symptomatic, intercurrent illness including but not limited to
infection, congestive heart failure, unstable angina pectoris, cardiac arrhythmia,
psychiatric illness, or social situations that would limit compliance with study
requirements or in the opinion of the PI would pose an unacceptable risk to the
subject;

12. Second malignancy other than in situ carcinoma of the cervix, unless the tumor was
treated with curative intent at least two years previously and subject is in
remission;

13. History of severe, immediate hypersensitivity reaction attributed to compounds of
similar chemical or biologic composition to any agents used in study or in the
manufacturing of the cells (i.e. gentamicin)

14. Severely impaired lung function defined as spirometry and DLCO that is 50% of the
normal predicted value corrected for hemoglobin and alveolar volume and/or oxygen
saturation that is 92% or less on room air while at rest. For patients who do not have
respiratory symptoms (e.g. dyspnea at rest, known requirement for supplemental oxygen
therapy), pulmonary function tests are not required.

For children who are unable to cooperate for PFTs, the criterion is: No evidence of
dyspnea at rest, no exercise intolerance and no requirement for supplemental oxygen
therapy.

15. Active macrophage activation syndrome (MAS) as evidenced by laboratory abnormalities
(e.g. elevated ferritin,, elevated triglycerides), hemophagocytosis on the bone marrow
sample, and/or clinical indications.