Non-Physiological Amino Acid (NPAA) Therapy in Pahenu2 Mice

Relevance to PKU Therapy

Mike Gibson, Professor and HeadSection of Clinical Pharmacology

Washington State University (WSU) SpokaneCollege of Pharmacy, Spokane WA

Disclosures: None

Rationale and Goals

• To Selectively Lower Brain Phenylalanine – NPAAs targeting L and A systems (BBB and gut)– Maintain Other LNAAs at or Near Normal Levels

• Adjuvant Therapy, Target Cognitive Improvements

Mammalian System L Transporters Specific for LNAAsTransporter Expression Amino AcidsTransported LAT-1 Li (fetal), BM, Br, Pl, Te L-I-V-F-Y-W-M-H LAT-2 Je, Ile, Ki, Pl, Br, Te, Sp L-F-W-T-N-I-C-S-Y-V-Q LAT-3 Pa, Li (fetal, adult), SM L-I-V-F LAT-4 Pl, Ki, Leuc L-F-I-M

Non-Physiological Amino Acids

A=Norleucine B=2-Aminoisobutyrate C=N-Methyl-2-aminoisobutyrate D=2-aminonorbornane-2-carboxylic acid

Only NL previously usedin a mammalian system

Km values of LNAAs for LAT(s) may lead to NPAA concentrations that selectively lower Phe while minimally altering other LNAAs

Brain Amino Acid Transport Systems

• ~ Amino Acid Specificity• Considerable Overlap• Glutamine (Q): Numerous• Na

Dependent/Independent• A ~ Smaller Amino Acids• L ~ Larger Amino Acids

Approach

• Dietary Administration-Clinical Relevance• Control Nitrogen Load with Casein• Monitor Brain LNAAs and Monoamines– Monitor Behavior/Movement in Future

• Blood Chemistries (Safety)– Assess Effects on Nitrogen Load

• Develop Methods to Quantify NPAAs

LNAA Metabolic Roles

Pilot Studies-Effect on Phe/TyrPhenylalanine Tyrosine

Results for Monoamines

Serotonin Dopamine

Additional LNAA Outcomes

Tryptophan Total Branched Chain AAs

Effects on 1-Methyl Transfer

Methionine SAMe

Conclusions

• Proof-of-Principle: Feasibility– Phe Reduction with NL, NB and MAIB– Other LNAA Effects: Lower Levels of NL and NB– Movement Effects of 3-5% NL Prominent– First Use of These in an Murine PKU Model

• MAIB is a Selective A System Inhibitor– Can Clearly Reduce Phe, However– Not Previously Documented– More Benign Effects than 5% NL, 0.5% NB

Goals in Future Studies

• Different Concentrations of NPAAs• Combinatorial Administration (BBB-Gut)• NPAA Characterization in High/Low Protein• Address Variability in Some LNAA Levels• Evaluate Method of Sacrifice• Characterize Behavior during NPAA

Intervention

AcknowledgementsColleagues/Funding

• Alliance Support• Kara Vogel• Brandi Wasek• Erland Arning• Terry Bottiglieri• R01 HD 58553• U54 DK 83916