Use of an oversized AAV8 vector for CPS1 deficiency results in long-term survival and ammonia control

Taryn Diep; Wesley Zhou; Rachel E. Reyes; Matthew Nitzahn; Isabel L. Day; Georgios Makris; Lindsay Lueptow; Irina Zhuravka; Stuti Bakshi; Jon Gangoiti; Hyacinth Padaon; Yunfeng Li; Bruce A. Barshop; Johannes Haberle; Gerald S. Lipshutz

Molecular Therapy: Nucleic Acids (Mar 2025)

Use of an oversized AAV8 vector for CPS1 deficiency results in long-term survival and ammonia control

Taryn Diep,
Wesley Zhou,
Rachel E. Reyes,
Matthew Nitzahn,
Isabel L. Day,
Georgios Makris,
Lindsay Lueptow,
Irina Zhuravka,
Stuti Bakshi,
Jon Gangoiti,
Hyacinth Padaon,
Yunfeng Li,
Bruce A. Barshop,
Johannes Haberle,
Gerald S. Lipshutz

Affiliations

Taryn Diep: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Wesley Zhou: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Rachel E. Reyes: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Pathology, Children’s Hospital, Los Angeles, CA, USA; School of Pharmacy, University of Southern California, Los Angeles, CA, USA
Matthew Nitzahn: Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Isabel L. Day: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Georgios Makris: Division of Metabolism and Children’s Research Center, University Children’s Hospital Zurich, Zurich, Switzerland
Lindsay Lueptow: Department of Psychology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Irina Zhuravka: Department of Psychology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Stuti Bakshi: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Jon Gangoiti: Department of Pediatrics, Division of Biochemical Genetics, University of California, San Diego, San Diego, CA, USA
Hyacinth Padaon: Department of Pediatrics, Division of Biochemical Genetics, University of California, San Diego, San Diego, CA, USA
Yunfeng Li: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Bruce A. Barshop: Department of Pediatrics, Division of Biochemical Genetics, University of California, San Diego, San Diego, CA, USA
Johannes Haberle: Division of Metabolism and Children’s Research Center, University Children’s Hospital Zurich, Zurich, Switzerland
Gerald S. Lipshutz: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Intellectual and Developmental Disabilities Research Center at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Semel Institute for Neuroscience, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Corresponding author: Gerald S. Lipshutz, Department of Surgery, David Geffen School of Medicine at UCLA, 757 Westwood Plaza, Room 8501G, Los Angeles, CA 90095-7054 USA.

Journal volume & issue: Vol. 36, no. 1
p. 102470

Abstract

Read online

Carbamoyl phosphate synthetase 1 (CPS1) deficiency, a urea-cycle disorder, results in hyperammonemia initiating a sequence of adverse events that can lead to coma and death if not treated rapidly. There is a high unmet need for an effective therapeutic for this disorder, especially in early neonatal patients where mortality is excessive. However, development of an adeno-associated virus (AAV)-based approach is hampered by large cDNA size and high protein requirement. We developed an oversized AAV vector as a gene therapy to treat CPS1 deficiency. In order to constrain genome size, we utilized small liver-specific promoter/enhancers and a minimal polyadenylation signal. Long-term survival (9 months, end of study) with ammonia control was achieved in AAV8.CPS1-administered Cps1flox/flox mice, while all null vector-injected controls died with marked hyperammonemia; female mice demonstrated improved survival over treated males. While glutamine remained elevated compared to controls, ammonia was controlled in surviving animals. Mice maintained their weights and were not sarcopenic. While drinking water did contain carglumic acid, no nitrogen scavengers were administered. Although there were concerns with vector genomic integrity, these findings demonstrate proof of concept for an oversized gene-therapy approach for a challenging urea-cycle disorder where high-level hepatic protein is essential for survival.

Published in Molecular Therapy: Nucleic Acids

ISSN: 2162-2531 (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Medicine: Therapeutics. Pharmacology
Website: https://www.cell.com/molecular-therapy-family/nucleic-acids/latest-content

About the journal

Abstract

Keywords