IFN-γ to Treat Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS) That Has Relapsed After Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloSCT) can cure patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, relapsed AML/MDS is the most significant single cause of treatment failure, and the majority of relapsed patients ultimately succumb. Alloreactive T cells in the donor graft can kill residual leukemia cells, mediating the graft-vs-leukemia (GVL) effect. Consistent with this, recipients of T cell-depleted grafts have higher rates of relapse. GVL is more potent against chronic leukemias than acute myeloblastic diseases, and the higher incidence of relapse in patients with AML/MDS reflects a failure in GVL. The central goal of this pilot trial will be to explore whether IFN-γ in this setting is safe and whether it has the desired biological activities on malignant blasts in vivo. IFN-γ will be tested in relapsed patients as monotherapy and in conjunction with donor leukocyte infusions (DLI). The clinical and biological information from this study is essential to design a phase II trial with a therapeutic endpoint. Treatment will be initiated at 100mcg (almost equal to the dose of 50 mcg/m2 for an adult) three times a week, with the potential to deescalate the frequency of injection for unacceptable toxicity. To explore whether this dosing regimen is sufficient to activate myeloblasts, pre- and post-treatment bone marrow specimens will be harvested to analyze for IFN-γ action (upregulation of HLA class I; HLA class II, ICAM-1 and phosphorylation of STAT1). The primary safety concern is the development of GVHD, which is routinely monitored for all alloSCT patients.