San Raffaele Telethon Institute for Gene Therapy

Goal 2. Be at the forefront of gene editing development

SR-Tiget Goal 2

CD40L def: CD40 ligand deficiency; FH: Familial Hypercholesterolemia; HD: Huntington’s Disease; HSC: Hematopoietic Stem Cells; RAG1 def: RAG1 deficiency

Targeted genome editing has opened the possibility to develop more precise genetic engineering strategies that may stringently reconstitute gene function and expression control by in situ gene correction and abrogate any residual risk of insertional mutagenesis by targeted integration. Successful application of homology-directed repair (HDR)-mediated and DNA break-free gene editing to hematopoietic stem cells (HSC) would establish new golden standards for precise genetic engineering of hematopoiesis.

After reporting the first pioneering studies of targeted gene editing of human HSCs, we have continued to contribute to the field by investigating adverse HSC responses to the procedure and improving the efficiency and yield of HDR-mediated gene editing by optimizing protocols and reagents. However, despite all these advances, several hurdles remain to be addressed before HDR-mediated gene editing might be safely and effectively applied to HSC gene therapy. Firstly, its efficiency in HSCs remains borderline for most clinical applications, with the likely exception of diseases where gene correction provides a selective growth advantage. In addition, the genotoxic risk of editing at the target site and genome-wide, and whether exploiting endonucleases, nucleotide deaminases or reverse transcriptases, remain to be fully explored.

We have thus embarked in a comprehensive R&D program aiming to further optimize the editing process in hematopoietic stem and progenitor cells by:

  1. systematic investigation and counteraction of adverse responses of treated cells;
  2. testing the potential of emerging break-less/free editors, including epigenome editors;
  3. devising strategies for enriching cells with the intended edit in the product to be administered;
  4. moving towards first clinical testing of the best performing protocol in diseases selected for providing the most suitable risk-benefit profile.

We expect to leverage on SR-Tiget proven capacity for developing early phase clinical trials of HSC-based therapies for inherited diseases, such as primary immunodeficiencies, to continue being at the forefront of technological advances and leading their translation towards the next generation GT.

Main Principal Investigators involved: AIUTI, DI MICCO, KAJASTE, LOMBARDO, NALDINI, VILLA.