Development and Clinical Application of Gene and Cell therapies for Patients with Immune Deficiencies

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

Our lentivector gene therapy clinical trial (IND 15041, NIAID IRB approved 11-I-0007) for treatment of older patients (aged 2 to 40 years) with X-linked Severe Combined Immunodeficiency is open. We treated four subjects this year, including two children from France, with immune deficiency and progressive medical problems despite prior transplant(s). The objectives of this study is to establish safety and efficacy of lentivector transduced autologous HSPCs in improving immunity and ameliorate clinical problems. Long-term follow up is necessary to establish the efficacy and safety of the LV-tranduced HSCs. Our goals are to develop gene and cell therapies for primary immunodeficiency diseases (PID). This program has a long history with the development and implementation of gene therapy for treatment of patients with PID. Currently we have active clinical trials using lentivector to treat Chronic Granulomatous Disease and X-linked Severe Combined Immunodeficiency. This experience has revealed advantages and shortcomings of these approaches and allow us to develop improvement to the cell manufacture procedures and treatment of patients to overcome problems such as low transduction efficiencies and development of autoimmune problems following cell infusion. To address low transduction efficiencies, we have incorporated the use of LentiBoost and prostaglandin (PEG2) during transduction. With these improved conditions, we have treated five patients in the past year, including two from France. We continue close surveillance of integration sites in all treated patients and are planning to modify the vector to improve safety. To aim at improving the specificity of gene insertion, we recently evaluated the CRISPR/Cas system to achieve specific genetic modifications in hematopoietic stem cells for gene therapy, and primary immune cells for cellular therapy. The goals are to restrict the genomic perturbation to the locus of interest and to restore physiological regulation of expression by the endogenous promoter. This approach relies on delivery of a DNA-break at a specific site (guided by single guide RNA), followed by homology-directed repair to incorporate the desired DNA change as determined by the donor, a short oligonucleotide for a mutation repair, or insertion of gene delivered by a engineered virus. The same delivery approach can be efficiently applied to HSPCs or to apheresis derived lymphocytes. To improve the efficiency of the desired homology-directed repair and to abrogate DNA damage response following exposure to AAV, we have added editing enhancers (i53 and GSE) to augment the efficacy of targeted insertion and cell viability with genome editing using CRISPR/Cas9. Encouraging preclinical data generated with these conditions is used for IND application to support clinical trials. The preclinical data is reported at scientific meetings and journals. Preliminary studies using a variety of base editor variants also demonstrate comparable gene correction efficacy rates. This is an exciting development due to its improved safety profile from the lack of double strand DNA breaks and possible increased specificity. We have ongoing studies to demonstrate the feasibility and safety of base-editing approaches on CD34+ HSCs for clinical applications. The goals of ex vivo gene therapy by infusion of gene-corrected hematopoietic stem/progenitor cells potentially provides long term benefit requires marrow preparation with conditioning agents such as busulfan. Cellular therapy with gene-corrected lymphocytes can potentially be used for treatment of infections prior to gene therapy or stem cell transplant. Choices of treatment approaches require good understanding of the pathogenesis of the disease. We work closely with colleagues who are experts in an array of PIDs and the disease pathogenesis to ensure optimal treatment approaches are developed. Another approach to restore function to primary lymphocytes and granulocytes from PID patients is to transfect the cells with therapeutic mRNA by electroporation. Donor granulocytes have been used to augment treatment of neutropenic or CGD patients with intractable invasive infections but carries risks of developing alloimmunization. Treatment using autologous cells addresses such concerns. While developing novel gene correction approaches, we continue to refine current lentivector-mediated gene therapy used for treating multiple PIDs, including the use of transduction enhancers (LentiBoost and Prostaglandin E2), and hope to apply this modality to treatment of patients with adenosine deaminase deficient SCID as well as Wiskott-Aldrich syndrome. Our hope is in generating specific novel therapeutic modalities appropriate for many rare immune-deficient genetic disorders.