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 mission is 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. We have a 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. The objectives of this study is to establish safety and efficacy of lentivector transduced autologous HSPCs in improving immunity and ameliorate clinical problems. To address problems related to low transduction efficiencies and need for large amounts of clinical vector for older/larger patients, we have incorporated the use of LentiBoost and prostaglandin (PEG2) during transduction. With these improved conditions, we have treated nineteen subjects to date. Our surveillance of the vector insert sites in peripheral blood cells of treated subjects led to our discovery of a cryptic splice acceptor within the vector that has led to aberrant fusion transcripts of vector and insert gene. This led resulted in HMGA2 clonal expansion observed in molecular studies but without any clinical or laboratory abnormalities. A modified version of the vector is in progress to continue the clinical trial. Long-term follow up is necessary to establish the efficacy and safety of the LV-transduced HSCs 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 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. We initiated a first-in-man mRNA correction of autologous granulocytes from CGD patients (FDA IND 27037; NIH Protocol 22-I-0001; ClinicalTrials.gov NCT05189925). The goal is to develop autologous granulocyte infusions for treatment of invasive infections in CGD patients. 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. An important milestone this year is that we obtained approval from FDA to initiate our first-in-man clinical trial in patients with X-linked Chronic Granulomatous Disease (CGD) (FDA IND 27037; NIH Protocol 22-I-0001; ClinicalTrials.gov NCT05189925). The objectives of the study is to evaluate the feasibility and safety of infusing autologous granulocytes (grans) from CGD patients that are functionally corrected by electroporation transfection with therapeutic mRNA. CGD patients are at risk of highly invasive infections. They can make grans like healthy individuals but their grans are non-functional because of their disease or gene mutation. By providing the mRNA, the cells are able to express the necessary protein to function, which in the case of grans, is to kill pathogens. This provides proof of concept that primary blood cells from patients can be made functional for short term purposes of infection control which improves their clinical status for subsequent higher-risk definitive treatment approaches such as gene therapy or allogeneic stem cell transplant.