Donor Th2 Cells to Prevent Graft-Versus-Host Disease in Bone Marrow Transplants

Allogeneic peripheral blood stem cell transplantation (PBSCT) is primarily limited by
graft-versus-host disease (GVHD). In murine models, we found that donor CD4+ Th1 cells
(secretion of IL-2 and IFN-Gamma) mediate GVHD. In contrast, donor Th2 cells (secretion of
IL-4 and IL-10) do not generate GVHD, and abrogate Th1-mediated GVHD. We also found that
murine allografts enriched with Th2 cells reduced GVHD without impairing the ability of donor
T cells to prevent graft rejection. These studies indicate that donor Th2 cells may be a new
approach to reducing GVHD.

In addition to GVHD, allogeneic PBSCT has been limited by toxicity associated with
conventional myeloablative preparative regimens. Although non-myeloablative regimens may
reduce regimen-related toxicity, such transplants have been associated with a 30 to 40%
incidence of severe acute GVHD (similar to rates observed with myeloablative regimens).
Because non-myeloablative regimens appear to have reduced regimen-related toxicity, we have
conducted this pilot study of Th2 cells in the setting of an immunoablative
(non-myeloablative) preparative regimen.

In this protocol, patients with lymphoid or hematologic malignancy receive induction therapy
(fludarabine and EPOCH) and transplant chemotherapy (fludarabine and cytoxan) to deplete host
T cells that mediate graft rejection. In our initial NCI cohort receiving HLA-matched
sibling, G-CSF mobilized PBSCT on this protocol (n=19), graft rejection was prevented in all
cases, with most recipients having 100% donor chimerism by day 28 post-SCT. With this reduced
intensity regimen, GVHD remained a significant complication, with 6/19 recipients having
grade II and 6/19 recipients having grade III acute GVHD. Importantly, potent
graft-versus-tumor responses were observed, with 9/19 patients remaining in complete
remission at a median of 17 months post-SCT.

Given that this allogeneic SCT regimen achieves engraftment and durable anti-tumor responses,
yet is associated with GVHD, this protocol represents an appropriate setting for evaluation
of donor Th2 cells. Initial patients will receive Th2 cells in a phase I manner. Three
patients will receive 5 x 10(6) Th2/kg, six patients will receive 2.5 x 10(7) Th2/kg, and six
patients will receive 1.25 x 10(8) Th2/kg. The highest dose of Th2 cells that results in an
acceptable toxicity profile (not more than 1/6 serious adverse events) and a favorable rate
of acute GVHD (not more than 2/6 cases of grade II or greater acute GVHD) will be selected
for the phase II study arm. Eighteen patients will be treated with allogeneic SCT and Th2
cells on this phase II study arm. In the event that Th2 recipients have reduced GVHD, further
clinical trials involving Th2 cells will be warranted.

- INCLUSION CRITERIA - Patient:

Patients with lymphoid malignancy and leukemia (including myelodysplasia) are candidates
for this study. The following diagnoses and ages will be considered:

Chronic Lymphocytic Leukemia, Age 18-75

1. Relapse Post-fludarabine, or

2. Non-CR after Salvage Regimen

Hodgkin's and Non-Hodgkin's Lymphoma (all types, including Mantle Cell Lymphoma), Age 18-75

1. Primary Treatment Failure, or

2. Relapse after AutoSCT, or

3. Non-CR after Salvage Regimen

Multiple Myeloma, Age 18-75

1. Primary Treatment Failure, or

2. Relapse after AutoSCT, or

3. Non-CR after Salvage Regimen

Acute Myelogenous Leukemia, Age 18-75

1. In CR #1, 2, or 3

2. Any Relapse with less than 10% blasts (marrow and blood)

Acute Lymphocytic Leukemia, Age 18-75

1. In Complete Remission #2

2. In Complete Remission #3

3. Any Relapse with less than 10% blast (marrow and blood).

Myelodysplastic Syndrome, Age 18-75

1. RAEB

2. RAEB-T (if blasts are less than 10% in marrow and blood after induction chemotherapy)

Chronic Myelogenous Leukemia, Age 18-75

1. Chronic Phase CML

2. Accelerated Phase CML

Patient age of at least 18 and not greater than 75 years of age.

Availability of 6/6 antigen (A, B, and DR) HLA-matched sibling donor.

Karnofsky performance status of greater than or equal to 70%.

Life expectancy greater than 3 months.

Serum bilirubin less than 2.5 mg/dL, and serum ALT and AST values less than or equal
to 2.5 times the upper limit of normal. Values above these levels may be accepted, at
the discretion of the PI or study chairman, if such elevations are thought to be due
to tumor involvement by the lymphoid malignancy. If these values do not normalize
during the induction chemotherapy, such patients will not be eligible for the
transplant phase of the protocol, and will thus be taken off study.

Creatinine clearance greater than or equal to 60 ml/min or serum creatinine of less
than or equal to 1.5 mg/dl.

DLCO greater than 50% of predicted.

Left ventricular ejection fraction of greater than or equal to 45% by MUGA or ECHO.

Ability to give informed consent.

Durable power of attorney form completed.

INCLUSION CRITERIA - Donor:

Must be sibling, matched with recipient at 6/6 of the HLA loci (A, B, and DR).

Adequate venous access for peripheral apheresis, or consent to use a temporary central
venous catheter for apheresis.

Must be at least 12 years of age.

Ability to give informed consent. For donors under 18 years of age, an assent form
must be completed.

EXCLUSION CRITERIA - Patient:

Infection that is not responding to anti-microbial therapy.

Active CNS involvement by tumor.

HIV positive (due to unacceptable risk after allogeneic transplantation).

Hepatitis B or C surface antigen positive.

Lactating or pregnant females (due to risk to fetus or newborn).

History of psychiatric disorder which may compromise compliance with transplant
protocol, or which does not allow for appropriate informed consent (as determined by
principal investigator or study chairman).

EXCLUSION CRITERIA - Donor:

History of psychiatric disorder which may compromise compliance with transplant
protocol, or which does not allow for appropriate informed consent.

History of hypertension that is not controlled by medication, stroke, or severe heart
disease. Individuals with symptomatic angina, or a history of coronary artery bypass
grafting or angioplasty will be considered to have severe heart disease, and thus will
not be eligible to be a donor.

Anemia (Hb less than 11 gm/dl) or thrombocytopenia (PLT less than 100,000 per ul).

Lactating or pregnant females.

HIV positive.

Hepatitis B or C antigen positive.