Rigel Pharma Gets Orphan Status for R289
FDA has granted Rigel Pharmaceuticals an orphan drug designation for R289 and its use in treating myelodysplastic syndromes (MDS). The “potent and selective” dual inhibitor of IRAK1 and IRAK4 is being studied in an ongoing Phase 1b study evaluating the safety, tolerability, pharmacokinetics and preliminary activity in patients with lower-risk (LR) MDS who are relapsed or refractory to prior therapies, Rigel says. R289 was previously granted fast track designation for treating patients with previously-treated transfusion transfusion-dependent lower-risk MDS.
Rigel says the drug has been shown in preclinical studies to block inflammatory cytokine production in response to toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) family signaling. “TLRs and IL-1Rs play a critical role in the innate immune response and dysregulation of these pathways can lead to various inflammatory conditions,” it says, adding that chronic stimulation of these systems is thought to cause the pro-inflammatory environment in the bone marrow responsible for persistent cytopenias in lower-risk MDS patients.