P15

Proof-of-concept for a one-step CRISPR-based gene therapy approach for STAT1 gain-of-function

C Iglesias-Herrero(1) T Kristoforus(1) S Perian(2) E Verhoeyen(2,3) R Schrijvers(1) R Gijsbers(1)

1:KU Leuven; 2:CIRI; Inserm U1111; 3:Université de Nice

Inborn errors of immunity (IEIs) are rare inherited disorders affecting the immune system presenting with increased susceptibility to pathogens and often associated with severe non-infectious comorbidities. The monogenic nature of IEIs converts them in a perfect target for precision medicine. Autosomal dominant (AD) signal transducer and activator of transcription 1 (STAT1) gain-of-function (GoF), which presents a wide range of mutations with a broad, mostly unexplained phenotype. STAT1 is a pivotal transcription factor in the immune response. Allogeneic hematopoietic stem cell transplantation, being the only curative option, comes with high morbidity and mortality. Gene editing offers a viable curative treatment for the patients given that STAT1 GoF is monogenic in nature. Here, we provide a proof-of-concept for a gene knock-in in STAT1 locus of genomic DNA by incorporating engineered virus-like particles and adeno-associated viral vectors to deliver CRISPR/Cas9 components and a donor template. Exploiting the homology-directed repair mechanism after Cas9-induced double-strand break, we report targeted integration in the STAT1 locus. Moreover, we are also able to achieve the endogenous regulation by STAT1 promoter. Our study highlights the potential of CRISPR/Cas9-mediated gene therapy for patients holding any mutation causing STAT1 GoF disease.