Developing Innovative Cell and Gene Therapy Strategies to Treat Fanconi Anemia

About This Grant

ABSTRACT/SUMMARY: Fanconi Anemia (FA) is the leading cause of inherited bone marrow failure (BMF) affecting thousands of patients worldwide. While allogenic (allo)-hematopoietic stem cell transplantation (HSCT) outcomes have been improving for FA patients, these treatments currently cause significant morbidity and mortality in part due to the non-specific and genotoxic chemotherapy and/or irradiation conditioning traditionally used pre-transplant. This is especially problematic in FA patients due to their exquisite sensitivity to DNA damage which results in DNA interstrand crosslinks (ICLs) and heightened risk of malignancies in all patients. Our long-term goal is to develop alternative non-toxic FA therapies using cell and gene therapy. Towards this goal, we have generated HSC-targeted conditioning approaches using monoclonal antibodies (mAbs) and mAb-drug-conjugates against the CD117 HSC cell-surface protein that clear host HSCs without non-specific tissue damage. However, from this research we have found that host HSC depletion is not critical in the FA setting. This has been further observed in the setting of autologous FANCA lentiviral gene therapy and somatic mosaicism, which have both shown that a small number of initial functional hematopoietic stem and progenitor cells (HSPCs) can stabilize hematopoiesis in FA patients. The overall objective of this work is to leverage distinctive strategies that elude the immune system to safely establish functional HSPCs in the bone marrow that can maintain hematopoiesis in the FA setting. The preliminary data supports a central hypothesis that stable hematopoiesis with ability to repair DNA ICLs can be established in FA without the use of genotoxic chemotherapy or irradiation due to the competitive advantage of functional HSPCs over failing FA HSPCs. This hypothesis will be tested through three specific aims in FA mice: 1) Achieving and optimizing haploidentical in utero HSCT without use of any conditioning, 2) Evaluating post-natal HSCT with immune conditioning alone, and 3) Developing HSC and systemic CRISPR-based base editing correction methods using engineered virus-like-particles (eVLPs) to stabilize host FA cells. The proposed research is both innovative and significant because it will identify multiple strategies that safely enable stabilization of hematopoiesis in the FA setting that will subsequently be translated into non-genotoxic therapies for FA patients. These novel approaches that enable functional HSC correction using both cell and gene therapy strategies are aimed at treatment of FA at different stages of hematopoietic disease, with the additional capacity to uniquely correct FA mutations in non-hematopoietic tissues. This work will have a major impact on improving treatment for FA patients and findings from this research will subsequently be utilized to improve the treatment of millions of people worldwide that suffer from diverse hematopoietic and genetic diseases.