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.
This study proposes a safe dosing regimen IFN-γ that is sufficient to stimulate IFN-γ receptors on malignant blasts in patients who developed relapsed acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) after alloSCT with no active or history of III-IV acute graft-versus-host disease (GVHD). It is hypothesized that IFN-γ will promote graft-vs-leukemia (GVL) in patients with AML/MDS that has relapsed after alloSCT.