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3633 Preclinical Assessment for Gene Addition Strategy in Familial Hemophagocytic Lymphohistiocytosis Related to Munc 13-4 Deficiency

Program: Oral and Poster Abstracts
Session: 801. Gene Therapies: Poster II
Hematology Disease Topics & Pathways:
Research, Biological therapies, Translational Research, Diseases, Immune Disorders, Gene Therapy, Therapies
Sunday, December 10, 2023, 6:00 PM-8:00 PM

Chantal Lagresle-Peyrou, PhD1*, Jean-Sebastien Diana, MD; PhD2*, Elisa Magrin, PharmD; PhD3*, Clotilde Aussel, PharmD; PhD3*, Natael Sorel1*, Yetki Aslan1*, Cécile Roudaut4*, Eden Schwartz, PharmD3*, Aurélie Gabrion5*, Caroline Tuchmann-Durand, PrarmD3*, Francois Lefrere, M.D3*, Anne Galy, PharmD, PhD6*, Despina Moshous, MD; PhD7* and Marina Cavazzana, MD, PhD8,9,10

1Institut Imagine, Paris, France
2Université de Paris Cité, Paris, France
3Necker Hospital (APHP), Paris, France
4Hopital Necker - Enfants Malades, Paris, FRA
5Hopital Necker Enfants-Malades, Paris, France
6INSERM U790 Genethon, Evry, FRA
7Hôpital Necker-Enfants Malades, Paris, FRA
8Department of Biotherapy, Hospital Necker, University Paris Descartes, Paris, France
9Imagine Institute, Paris, FRA
10Biotherapy Clinical Investigation Center, Inserm Assistance Publique Hôpitaux de Paris, Paris, France

Introduction: Familial Hemophagocytic Lymphohistiocytosis (FHL) comprises a group of rare genetic disorders with defect cytotoxicity in T and NK cells predisposing to severe hyperinflammation with the clinical hallmark of the Hemophagocytic LymphoHistiocytosis (HLH) syndrome. The uncontrolled proliferation of activated T-CD8 lymphocytes and macrophages infiltrates lymphoid tissues, bone marrow, and multiple organs including the brain. Thus, if untreated full-scale FHL is usually fatal. FHL3 is due to mutations in the UNC13D gene coding for Munc 13-4 protein, one of the components of the perforin-dependent cytotoxicity apparatus. This condition accounts for 30% to 35 % of all genetic cases of HLH. Hematopoietic stem and progenitor cell (HSPC) transplantation, which is the only curative treatment for FHL3 to date, remains difficult even when a compatible donor is available because of the patients’ critical inflammatory background. In this context, gene therapy could be a promising therapeutic option, especially for those patients without HLA-compatible donor.

Method: The feasibility and efficacy of gene addition strategy for FHL3 have been previously demonstrated in mouse models. We then translated this approach to human cells using a third-generation self-inactivated lentivirus vector pseudo-typed with a conventional vesicular stomatitis virus-G (VSVG) expressing a codon-optimized UNC13D gene under the transcriptional control of EF1 alpha (LV-EF1a-UNC13D). HSPC or CD3+ T-cells were transduced with a GMP-like-grade LV-EF1a-UNC13D lentiviral vector. We studied the restoration of cytotoxic function.

Results: Our GMP transduction protocol led to efficient transcription of optimized mRNA codon and expression of Munc 13-4 protein as evidenced by RT qPCR and western blot, respectively. Interestingly, we show restored cytotoxicity activity after CD34+ differentiation toward CD3+ T-cells and NK cells. The vector copy number is compatible with a clinical approach. In vivo experiments are ongoing to validate the absence of genotoxicity in this setting.

Discussion conclusion: Our results support the feasibility and efficacy of UNCD13D gene transfer into hematopoietic stem and progenitor cells or T cells from Munc 13-4 deficient patients. Alternatively, gene therapy of HSPCs could be combined with transduced autologous T-cells infusion. The first attempts regarding this option are encouraging. UNC13D gene addition strategy could dramatically improve the care of FHL3 patients lacking an HLA-genoidentical donor.

Disclosures: No relevant conflicts of interest to declare.

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