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Principal Investigator: Xiao Wang
Organization: UNIVERSITY OF PENNSYLVANIA
Fiscal Year: 2024
Award: $675,157
Funding agency: Eunice Kennedy Shriver National Institute of Child Health and Human Development
PROJECT SUMMARY
Phenylketonuria (PKU) is an autosomal recessive disorder caused by mutations in the gene encoding
phenylalanine hydroxylase (PAH), resulting in the accumulation of phenylalanine (Phe) to neurotoxic levels.
Although there are treatment options, ranging from a strict low-Phe diet to an oral medication (sapropterin, a
cofactor of PAH) to an injectable enzyme substitution therapy (pegvaliase), many PKU patients find it challenging
to adhere to the dietary intervention and have limited responses to or access to the medical therapies and, as a
result, have impaired cognitive development and develop a range of neuropsychiatric problems. Durable and,
ideally, curative therapies are needed to address the unmet medical needs of PKU patients.
More than 1,000 PAH variants have been cataloged in patients. These vary in their consequences for PAH
activity, from having little or no effect to eliminating PAH activity completely. Certain variants occur much more
commonly than others in PKU patients. The most frequently occurring pathogenic PAH variant worldwide is the
R408W (c.1222C>T, p.Arg408Trp) variant. Patients homozygous for this variant do not respond to sapropterin,
limiting their treatment options.
In vivo gene editing is an emerging therapeutic approach to making DNA modifications in the body of a patient,
such as in the liver. Gene-editing tools include nucleases, cytosine base editors, adenine base editors, and prime
editors. CRISPR base editors and prime editors are attractive because they can function efficiently for introducing
precise targeted alterations without the need for double-strand breaks, in contrast to CRISPR-Cas9 and other
gene-editing nucleases. We and others have demonstrated the ability of base editors to make specific DNA edits
with very high efficiency and limited off-target effects in the liver in mouse models and non-human primates.
We now seek to assess whether a one-time delivery of adenine base editing or prime editing can be used to
permanently correct the human PAH R408W variant in human hepatocytes in vitro and in the liver in humanized
mice in vivo efficiently and safely and, if so, the optimal editing system to use for this purpose. Success in
completing this translational project will provide critical information on the feasibility of an in vivo genome-
editing approach that could ultimately yield a one-shot, long-term therapy that permanently corrects the most
frequent PAH pathogenic variant and thus serves as a potential cure for PKU patients with this variant. The
proposed work, if successful, could open the door to a new therapeutic modality for many PKU patients—
not just for patients with the PAH R408W variant, but those with other editable pathogenic variants in the PAH
gene—as well as patients with such variants in other liver-expressed, disease-associated genes.
Terms: <1H-Purin-6-amine><AAV vector><AAV-based vector><Aberrant Chromosome><Address><Adenine><Amino Acids><CRISPR><CRISPR approach><CRISPR based approach><CRISPR method><CRISPR methodology><CRISPR technique><CRISPR technology><CRISPR tools><CRISPR-CAS-9><CRISPR-based method><CRISPR-based technique><CRISPR-based technology><CRISPR-based tool><CRISPR/CAS approach><CRISPR/Cas method><CRISPR/Cas system><CRISPR/Cas technology><CRISPR/Cas9><CRISPR/Cas9 technology><Cas nuclease technology><Chromosomal Aberrations><Chromosomal Abnormalities><Chromosomal Alterations><Chromosome Aberrations><Chromosome Alterations><Chromosome Anomalies><Chromosome abnormality><Chromosomes><Classical phenylketonuria><Clustered Regularly Interspaced Short Palindromic Repeats><Clustered Regularly Interspaced Short Palindromic Repeats approach><Clustered Regularly Interspaced Short Palindromic Repeats method><Clustered Regularly Interspaced Short Palindromic Repeats methodology><Clustered Regularly Interspaced Short Palindromic Repeats technique><Clustered Regularly Interspaced Short Palindromic Repeats technology><Cognitive Disturbance><Cognitive Impairment><Cognitive decline><Cognitive function abnormal><Cytogenetic Aberrations><Cytogenetic Abnormalities><Cytosine><DNA><DNA Modification><DNA Modification Process><Deoxyribonucleic Acid><Diet><Dietary Intervention><Disease><Disorder><Disturbance in cognition><Drugs><Enzyme Gene><Enzymes><Folling's Disease><Gene variant><Genes><Genetic Alteration><Genetic Change><Genetic Diversity><Genetic Variation><Genetic defect><Guide RNA><Hepatic Cells><Hepatic Parenchymal Cell><Hepatocyte><Hereditary Disease><Human><Human Genetics><Impaired cognition><In Vitro><Inborn Genetic Diseases><Inherited disorder><Injectable><Liver><Liver Cells><Medical><Medication><Methods><Modality><Modern Man><Mutation><Nutrition Interventions><Nutritional Interventions><Oligo><Oligonucleotides><Oral><Pathogenicity><Patients><Pharmaceutical Preparations><Phenylalanine><Phenylalanine 4-Hydroxylase><Phenylalanine 4-Monooxygenase><Phenylalanine Hydroxylase><Phenylalanine Hydroxylase Deficiency Disease><Phenylalanine hydroxylase deficiency><Phenylketonurias><Safety><Severe Phenylalanine Hydroxylase Deficiency Disease><System><Therapeutic><Therapeutic Gene Editing><Variant><Variation><Vitamin B4><Work><adeno-associated viral vector><adeno-associated virus vector><allele variant><allelic variant><aminoacid><autosome><base editing><base editor><chromosomal defect><chromosome defect><chromothripsis><cofactor><cognitive development><cognitive dysfunction><cognitive loss><curative intervention><curative therapeutic><curative therapy><curative treatments><determine efficacy><diet intervention><diets><disease causing variant><disease-causing mutation><drug/agent><efficacy analysis><efficacy assessment><efficacy determination><efficacy evaluation><efficacy examination><evaluate efficacy><examine efficacy><experience><gRNA><gene editing platform><gene editing system><gene editing technology><gene editing tools><gene-editing therapy><gene-editing toolkit><genetic variant><genome editing><genome editing based therapy><genome editing therapy><genome editing treatment><genome editing-based therapeutics><genome mutation><genomic editing><genomic variant><hepatic body system><hepatic organ system><hepatoma cell><hereditary disorder><heritable disorder><humanized mice><humanized mouse><in vivo><in vivo Model><inborn error><inherited diseases><inherited genetic disease><inherited genetic disorder><lipid based nanoparticle><lipid nanoparticle><minimal risk><mouse model><murine model><neuropsychiatric><neuropsychiatry><neurotoxic><new drug treatments><new drugs><new pharmacological therapeutic><new therapeutics><new therapy><next generation therapeutics><non-human primate><nonhuman primate><novel><novel drug treatments><novel drugs><novel pharmaco-therapeutic><novel pharmacological therapeutic><novel therapeutics><novel therapy><nuclease><oligos><pathogenic variant><phenylalaninase><phenylalaninemia><phenylpyruvic oligophrenia><prime editing><prime editor><response><success><therapeutic editing><therapeutic genome editing>