New research describes a molecular tool that shows great promise as a therapeutic for human acute myeloid leukemia (AML), a notoriously treatment-resistant blood cancer. The study, published in the July 2nd issue of the journal Cell Stem Cell, describes exciting preclinical studies in which a new therapeutic approach selectively attacks human cancer cells grown in the lab and in animal models of leukemia.This news release is about the article Monoclonal antibody-mediated targeting of CD123, IL-3 receptor alpha chain, eliminates human acute myeloid leukemic stem cells by Liqing Jin and 14 co-authors, including John E Dick and Richard B Lock, Cell Stem Cell 2009(Jul 2); 5(1): 31-42. PubMed Abstract:
Leukemia stem cells (LSCs) initiate and sustain the acute myeloid leukemia (AML) clonal hierarchy and possess biological properties rendering them resistant to conventional chemotherapy. The poor survival of AML patients raises expectations that LSC-targeted therapies might achieve durable remissions. We report that an anti-interleukin-3 (IL-3) receptor alpha chain (CD123)-neutralizing antibody (7G3) targeted AML-LSCs, impairing homing to bone marrow (BM) and activating innate immunity of nonobese diabetic/severe-combined immunodeficient (NOD/SCID) mice. 7G3 treatment profoundly reduced AML-LSC engraftment and improved mouse survival. Mice with pre-established disease showed reduced AML burden in the BM and periphery and impaired secondary transplantation upon treatment, establishing that AML-LSCs were directly targeted. 7G3 inhibited IL-3-mediated intracellular signaling of isolated AML CD34(+)CD38(-) cells in vitro and reduced their survival. These results provide clear validation for therapeutic monoclonal antibody (mAb) targeting of AML-LSCs and for translation of in vivo preclinical research findings toward a clinical application.