Novel therapeutic gene editing to induce fetal hemoglobin for sickle cell disease

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PROJECT SUMMARY Despite advances in the medical care of sickle cell disease (SCD), most patients continue to experience debilitating pain, poor quality of life, progressive organ deterioration, and premature death. We are developing a novel, potentially curative therapy for SCD based on genome editing of autologous hematopoietic stem cells (HSCs) to induce the production of fetal hemoglobin (HbF, 22) in red blood cells (RBCs). Natural genetic variants can generate high levels of HbF that alleviate or eliminate the pathophysiology of SCD. Our published studies show that one of these variants can be recreated by Cas9-mediated disruption of a -globin gene promoter motif recognized by BCL11A, a transcriptional repressor protein that drives the normal perinatal switch from -globin to -globin expression. New preliminary data show that transfection of normal or SCD patient donor CD34+ cells with ribonucleoprotein (RNP) complex consisting of Cas9 and guide RNA (gRNA) targeting the BCL11A binding motif, followed by xenotransplantation into immunodeficient mice, consistently achieved ≥70% on-target editing in bone marrow-repopulating HSCs, with no off-target mutations detected by rigorous genome- wide activity analysis at a sensitivity of 0.1%. The modified HSCs generated RBCs in vivo with >30% pancellular HbF and 18-31% sickling in 2% O2, compared to <5% HbF and 62-71% sickling in unmodified control RBCs (P<0.0001). We will now translate our findings “from bench to bedside” by designing and carrying out a first-in- human clinical study, termed St. Jude Autologous Genome Edited Stem Cells (SAGES1), examining the safety and efficacy of autologous -globin promoter-edited CD34+ cells (drug product SJ-1001) according to 3 Aims. Aim 1 will define the mechanism of action, potency, and safety profile of SJ-1001 through FDA-enabling and exploratory research studies. Aim 2 will establish cGMP clinical scale manufacturing of SJ-1001 by optimizing process development, generating drug product release assays for the clinical trial, and transferring these protocols to the St. Jude current good manufacturing practice (cGMP) facility. Aim 3 will establish and manage the SAGES1 clinical trial to evaluate one-time SJ-1001 infusion as a cure for SCD. This will include the development of an enhanced multidisciplinary informed consent process, safety and efficacy assessments, and post therapy mechanistic studies. Our work has the potential to relieve suffering and extend the lifespan of thousands of patients with severe SCD.