Research in my laboratory has made critical findings related to the molecular, cellular, and genetic basis of Myelodysplastic Syndromes (MDS), a complex and poorly understood hematopoietic stem cell (HSC) failure syndrome. The complexity and heterogeneity of MDS, and the lack of mouse models, remain as major obstacles to understanding and effectively treating this disease. Overexpression of immune-related genes is widely reported in MDS, and chronic innate immune pathway activation, primarily via Toll-like receptors (TLRs), increases the risk of developing MDS. Multiple independent mechanisms contribute to hyperactivation of TLR signaling in MDS, which converge on the central complex involving IRAK1, IRAK4, and TRAF6. Based on our published and preliminary data, IRAK1 and IRAK4 (IRAK1/4), a dual kinase complex is activated in MDS patients. Moreover, the importance of the IRAK1/4-TRAF6 complex in primary MDS comes from our recent observation that describes genetic and pharmacologic approaches to inhibit IRAK1/4 as effective agents to suppress TRAF6 and the MDS clone. Collectively, these molecular and genetic alterations clearly implicate IRAK1/4-TRAF6 signaling as a pathogenic driver and druggable complex in MDS. Therefore, we hypothesize that small molecule dual inhibitors of IRAK1 and IRAK4 will suppress MDS-propagating cells. We derived a novel chemical series of potent dual IRAK1/4 inhibitors. The lead compound shows potent inhibition of IRAK1 and IRAK4 in MDS, efficacy at suppressing MDS cell viability and function in vitro, and promising pharmacokinetic and pharmacodynamics properties in vivo. As such, the objective of this proposal is to optimize and evaluate our candidate dual IRAK1/4 inhibitors in human MDS cells in vitro (Aim 1), and in mouse and human MDS models in vivo (Aim 2).
The specific aims will provide necessary preclinical information on the therapeutic potential of rationally designed dual IRAK1/4 inhibitors for future human MDS trials.

Public Health Relevance

Myelodysplastic syndromes (MDS) are a collection of acquired or inherited diseases wherein the bone marrow produces too few blood cells, and patients progress to acute leukemia. We idenitified that aberrant activation of the Toll-like receptor (TLR) pathway is a unifying driver of MDS pathogenesis, and that IRAK1/4, a central mediator of TLR signaling in MDS, is a druggable target. The objective of this proposal is to develop drug-like dual IRAK1/4 inhibitors for MDS. The specific aims will provide necessary preclinical information on the therapeutic potential of rationally designed dual IRAK1/4 inhibitors for future human MDS trials.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Drug Discovery and Molecular Pharmacology Study Section (DMP)
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Roy, Cindy
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Cincinnati Children's Hospital Medical Center
United States
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Fang, Jing; Muto, Tomoya; Kleppe, Maria et al. (2018) TRAF6 Mediates Basal Activation of NF-?B Necessary for Hematopoietic Stem Cell Homeostasis. Cell Rep 22:1250-1262
Culver-Cochran, Ashley E; Starczynowski, Daniel T (2018) Chronic innate immune signaling results in ubiquitination of splicing machinery. Cell Cycle 17:407-409
Fang, Jing; Bolanos, Lyndsey C; Choi, Kwangmin et al. (2017) Corrigendum: Ubiquitination of hnRNPA1 by TRAF6 links chronic innate immune signaling with myelodysplasia. Nat Immunol 18:474
Niederkorn, Madeline; Starczynowski, Daniel T (2017) GMP-ing to Spatial Conclusions about Emergency and Leukemic Myelopoiesis. Cell Stem Cell 20:579-581