Monitoring of Vector Integration Sites in In Vivo Gene Therapy Approaches by Liquid-Biopsy-Integration-Site Sequencing

Highlights From the ESGCT 28th Annual Congress

Monitoring of Vector Integration Sites in In Vivo Gene Therapy Approaches by Liquid-Biopsy-Integration-Site Sequencing

D Cesana¹, A Calabria¹, L Rudilosso¹, P Gallina¹, G Spinozzi¹, A Magnani², M Pouzolles³, F Fumagalli¹, V Calbi¹, M Witzel⁴, F D Bushman⁵, A Cantore¹, N Taylor³, V S Zimmermann³, C Klein⁴, A Fischer², M Cavazzana², E Six², A Aiuti¹, L Naldini¹, E Montini¹

¹San Raffaele Telethon Insitute for Gene Therapy (HSR-TIGET)

²Laboratory of Human Lymphohematopoiesis, INSERM, France

³Institut de Génétique Moléculaire de Montpellier, CNRS, France

⁴Dr. von Hauner Children's Hospital, LMU, Germany

⁵Department of Microbiology, UPenn, USA

Key Data Points

IS Retrieval From Cell-free DNA Purified From Body Fluids
Characterization of Lentivirus (LV) Integration Profile in Hemophilic Dogs

IS Retrieval From Cell-free DNA Purified From Body Fluids

Cell-free DNA (cfDNA) is released into the blood from healthy, inflamed, or diseased solid organ cells (such as liver or thymus) undergoing apoptosis or necrosis. Genetic alterations in purified cfDNA, including vector–genomic integration sites (IS) from transduced cells, can be detected by liquid biopsy integration site sequencing (LiBIS-seq).

Three adult hemophilic dogs (O21, M57, and O59) received a single injection of LVs expressing different versions of canine coagulation FIX. For each dog, cfDNA was purified from blood serum harvested at 7–8 different time points starting from 30 to 532 d after injection. This graph shows the estimated population size of marked cell clones contributing to the shared ISs over time in dogs M57 and O59.