Modern frontline therapy for patients with hematologic malignancies is based on intensive administration of multiple drugs. In patients with relapsed disease, response to the same drugs is generally poor, and dosages cannot be further increased without unacceptable toxicities. For most patients, particularly those who relapse while still receiving frontline therapy, the only therapeutic option is hematopoietic stem cell transplantation (SCT). For those who relapse after transplant, or who are not eligible for transplant because of persistent disease, there is no proven curative therapy.

There is mounting evidence that NK cells have powerful anti-leukemia activity. In patients undergoing allogeneic SCT, several studies have demonstrated NK-mediated anti-leukemic activity. NK cell infusions in patients with primary refractory or multiple-relapsed leukemia have been shown to be well tolerated and void of graft-versus-host disease (GVHD) effects. Myeloid leukemias are particularly sensitive to NK cells cytotoxicity, while B-lineage acute lymphoblastic leukemia (ALL) cells are often NK-resistant.

We have developed a novel method to expand NK cells and enhance their cytotoxicity. Expanded and activated donor NK cells have shown powerful anti-leukemic activity against acute myeloid leukemia (AML) cells and T-lineage ALL cells in vitro and in animal models of leukemia.

The present study represents the translation of these laboratory findings into clinical application.. We propose to determine the safety of infusing expanded NK cells in pediatric patients who have chemotherapy refractory or relapse hematologic malignancies including AML, T-lineage ALL, T-cell lymphoblastic lymphoma (T-LL), chronic myelogenous leukemia (CML), juvenile myelomonocytic leukemia (JMML), and myelodysplastic syndrome (MDS). The NK cells used for this study will be obtained from the patient's family member who will be a partial match to the patient's immune type (HLA type).