The Evolving Role of Current and Novel Therapies in Improving Outcomes in Adults with PKU

The Evolving Role of Current and Novel Therapies in Improving Outcomes in Adults With PKU

The symposium is not part of the official ACMG Annual Meeting program, and ACMG does not approve or endorse any commercial products or services discussed during the symposium or offered for sale by the corporate supporter of the symposium. ACMG has reviewed and approved this symposium as appropriate for presentation as an independent educational activity held in conjunction with the ACMG Annual Meeting. Disclosures

Barbara K. Burton, MD, has a financial interest/relationship or affiliation in the form of: Consultant for BioMarin Pharmaceutical Inc.; Horizon Pharma; REGENXBIO Inc.; Reneo Pharmaceuticals, Inc.; Shire; and Viking Therapeutics. Grant/Research Support from Sangamo Therapeutics, Inc.; Shire; and Ultragenyx Pharmaceutical. Speakers Bureau participant with Alexion Pharmaceuticals Inc.; Sanofi Genzyme; and Shire. Advisory Board for Alexion Pharmaceuticals Inc. and Shire. Other Financial or Material Support from Horizon Pharma for the Data and Safety Monitoring Board. BioMarin Pharmaceutical Inc. for clinical trial steering committee.

Barbara K. Burton, MD, does intend to discuss either non–FDA-approved or investigational use for the following products/devices: treatments for phenylketonuria.

This CME activity is jointly provided by Medical Learning Institute, Inc. and PVI, PeerView Institute for Medical Education. This activity is supported by an educational grant from BioMarin Pharmaceuticals Inc. Disclosures

Nicola Longo, MD, PhD, has a financial interest/relationship or affiliation in the form of: Consultant for Aeglea BioTherapeutics; BioMarin; Censa Pharmaceuticals; Dimension Therapeutics; Genzyme Corporation/sanofi-aventis U.S. LLC; HemoShear Therapeutics, LLC; Horizon Pharma plc; Lumos Pharma; Mitobridge, Inc.; Moderna Therapeutics; Pfizer Inc.; Retrophin, Inc.; and Stealth BioTherapeutics Inc. Grant/Research Support from Lumos Pharma. Clinical Trial Support for Aeglea BioTherapeutics; BioMarin; Censa Pharmaceuticals; Genzyme Corporation/sanofi-aventis U.S. LLC; Horizon Pharma plc; Pfizer Inc.; Protalix Ltd.; Retrophin, Inc.; Shire; Stealth BioTherapeutics Inc.; and Ultragenyx Pharmaceutical. Travel Support for Cello Health and Sigma-Tau Pharmaceuticals, Inc./Alfasigma USA, Inc.

Nicola Longo, MD, PhD, does intend to discuss either non–FDA-approved or investigational use for the following products/devices: treatments for phenylketonuria.

CME Reviewer Medical Director Staci M. Kallish, DO Kirk A. Tacka, PhD University of Pennsylvania School of Medicine PVI, PeerView Institute for Medical Education Philadelphia, Pennsylvania Kirk A. Tacka, PhD, has no financial Staci M. Kallish, DO, has no financial interests/relationships or affiliations in relation to interests/relationships or affiliations in relation to this activity. this activity.

The associates of Medical Learning Institute, Inc., the accredited provider for this activity, and PVI, PeerView Institute for Medical Education do not have any financial relationships or relationships to products or devices with any commercial interest related to the content of this CME activity during the past 12 months.

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Barbara K. Burton, MD Professor of Pediatrics Northwestern University Feinberg School of Medicine Photo Director, PKU Clinic Pending Ann & Robert H. Lurie Children’s Hospital of Chicago Chicago, Illinois Phenylketonuria (PKU)1

Autosomal Recessive Inborn Error Characterized by Mutations in Gene of Metabolism Affecting Phenylalanine Encoding for the Hepatic Enzyme, (Phe) Catabolic Pathway Phenylalanine Hydroxylase Chromosome 12

PAH gene (12q22-12q24.2)

 >500 known mutations  Identified by newborn screening  Incidence: 1:10,000 to 1:15,000

1. Vockley J et al. Genet Med. 2014;16:188-200. Phenylalanine Metabolism: A Simplified View1

Phenylalanine Hydroxylase (PAH)

Phenylalanine Tyrosine BH4 (cofactor) and O2

1. Vockley J et al. Genet Med. 2014;16:188-200. Alterations in Phenylalanine Metabolism in PKU1

PAH Defective

BH (cofactor) and O Phenylalanine 4 2 Tyrosine Phenylpyruvic acid

Phenyllactic acid Phenylacetic acid

1. Vockley J et al. Genet Med. 2014;16:188-200. Clinical Manifestations of Neurocognitive and Neuropsychiatric Effects in Early Treated PKU1-6

Executive Function Deficits Psychiatric Symptoms Psychological Behavioral • Depression • ADHD • Agoraphobia • Anxiety • Self-harm • Agitation • Mood swings • Schizophrenia

Neurological Abnormalities • Spasticity • Gait disturbances • Tremor • Seizures

1. Channon S et al. Neuropsychology. 2004;18:613-620. 2. Brumm VL et al. Mol Genet. 2010;99:S59-S63. 3. Sullivan JE, Chang P. J Pediatr Psychol. 1999;24:281-299. 4. Burton BK et al. Mol Genet Metabol. 2013;108:8-12. 5. Waisbren SE, Levy HL. J Inherit Metab Dis. 1991;14:755-764. 6. Pietz K. Curr Opin Neurol. 1998;11:679-688. Executive Function Deficits in PKU1

P < .001

a 20 15 10 5 Range, % Range, 5

Children in Severe in Children 0 Control PKU

a Based on Behavior Rating Inventory of Executive Function (BRIEF) Global Executive Composite; severe range is >1 SD above the mean. 1. Anderson VA et al. Child Neuropsychol. 2002;8:231-240. Neuropsychiatric Comorbidities in Adults With PKU1

25 General population a PKU 19.5 20 b Rates of intellectual disability, 15.6 anxiety, and depression 15 significantly higher for PKU 11.8 cohort vs general population 10 9.2

Adults, % Adults, a cohort across all age groups 4.8 (20-29, 30-39, 40-49, 50-59, 5 60-69, and 70+ years of age) 0.6 0 Intellectual Anxiety Depression Disability a P < .0001. b P = .0001. 1. Bilder D et al. Mol Genet Metabol. 2017;121:1-8. Overall Burden of PKU1

PKU Burden

Health Status Psychological Family Life Social Function • Cognitive Function • Future family • Isolation function • Mood changes • Psychological • Relationships • Symptoms • Emotions impact on • School • Monitoring • Feelings family members • Work

1. Regnault A et al. Oprhanet J Rare Dis. 2015;10:59-76. Moving on to This Evening’s Agenda

First, we’ll review current guidelines for PKU management and consider their relevance to adult patients

Then, we’ll discuss available data on approved and emerging adjunctive pharmacologic approaches for the treatment of PKU

Be prepared for polling questions both before and during tonight’s scientific sessions Contemporary Practice Guidelines for Maintaining Metabolic Control and Mitigating the Neurocognitive Impairments of PKU How Are They Pertinent to Adult Patients?

Nicola Longo, MD, PhD Professor and Chief Medical Genetics/Pediatrics Photo University of Utah Pending Salt Lake City, Utah Goals of Treatment in Patients With PKU1

120 to 360 μM Control blood [Phe] in all patientsa

Ongoing Monitoring • Phe and tyrosine testing • Nutritional markers and micronutrients • Plasma amino acids and protein status • Bone density • Neuropsychological testing aEuropean guidelines: recommended blood [Phe] range for patients > 12 years of age =120-600 μM2 1. Vockley J et al. Genet Med. 2014;16:188-200. 2. van Wegberg AMJ, et al. Orphanet J Rare Dis. 2017;12(1):162. Dietary Management of PKU1,2

• Omission of all high-protein food • Inclusion of modified low-protein food • Replacement of restricted protein and calories with metabolic formulas − Contain Phe-free proteins, fats, carbohydrates − Supplemented with tyrosine, vitamins, minerals However …

1. Vockley J et al. Genet Med. 2014;16:188-200. 2. Singh R et al. Genet Med. 2014;16:121-131. Dietary Management Also Contributes to Overall Burden of PKU1

Phe-Free Health Status Supplements • Cognitive PKU • Daily life function Burden • Social • Symptoms • Taste • Monitoring • Convenience

Psychological Social Diet Family Life Function Function • Daily life • Future family • Mood • Isolation • Food • Impact on changes • Relationships • Social family • Emotions • School • Psychological members • Feelings • Work • Family

Consequently…

1. Regnault A et al. Oprhanet J Rare Dis. 2015;10:59-76. Compliance With Dietary Treatment Decreases With Age1

Plasma [Phe] increases

with age as children have a /L

more varied diet and start mol

μ having a social life.

], ],

Phe [

1. Viau KS et al. J Inherit Metab Dis. 2001;34:963-971. Compliance With Medical Nutritional Therapy Decreases With Age1

Above target range Within target range Below target range

100% 4% 4% 1% 1% 2% 3%

31% 80% 49% 41% 60% 70% 73% 84% 40% 67%

Patients 58% 20% 50% 27% 12% 24% 0% 0-4 Years (N=625) 5-12 Years (N=900) 13-17 Years (N=608) 18-29 Years (N=658) ≥ 30 years (N=687) Pregnant/Planning on Becoming Pregnant (N=106) 0-4 y 5-12 y 13-17 y 18-29 y ≥30 y Pregnant/ (N = 625) (N = 900) (N = 608) (N = 658) (N = 687) Planning Pregnancy Many adult patients with PKU are (N = 106) not followed at metabolic clinics

1. Jurecki ER et al. Mol Genet Metab. 2017;120:190-197. Children With PKU on Diet Have Significantly Lower

IQ Than Unaffected Peers and Sibling Controls1,2

120 P < .0001 120 P = .001 112 110 110 107 102 100 100 100

90 90

Peers PKU 80 80 Siblings PKU n = 21 a n = 26b n = 55 c Peers Scale Intelligence Wechsler PKU Wechsler Intelligence Scale Intelligence Wechsler PKU Siblings (n = 21) (n = 26) (n = 55) (n = 55) a Controls were age and sex matched. b Ages 7 to 19 years, managed early and continuously with Phe-restricted diet. c Children aged 8 years with PKU; direct relationship between IQ and Phe level over preceding 6 months. 1. Gassio R et al. Pediatr Neurol. 2005;33:267-271. 2. Koch R et al. J Inherit Metab Dis. 1984;7:86-90. Blood Phe and IQ Are Significantly Correlated in Patients With PKU1

Lifetime IQ Loss for Each Range of Blood Observation Period 100 μmol/L Increase [Phe], μmol/L in Blood [Phe], IQ Points Critical period 423-750 1.3-3.1 (ages 0-12 y) Lifetime 394-666 1.9-4.1 (all ages up to 18 y) Data based on meta-analysis of 40 studies and 3,361 patients with PKU

1. Waisbren SE et al. Mol Genet Metab. 2007;92:63-70. Phenylketonuria in Adults1

• Mood and psychiatric disorders seem more frequent in adults with PKU than in general population – Executive function is also compromised • In adults with PKU, trials have been done to decrease or increase Phe levels – In general, higher [Phe] associated with worsening of behavior (even in individuals with intellectual disability missed by newborn screening), and lowering of [Phe] improved behavior and mood in addition to executive function

1. Bilder DA et al. Dev Neuropscyhol. 2016;41:245-260. Effects of Phe-Restricted Diet in Adults With PKU1-9

Multiple blinded crossover studies and single-cohort interventional studies have shown Phe-restricted diet is effective in lowering blood [Phe] in adults with PKU

Although measures and results varied, better neuropsychiatric outcomes were associated with on-diet and/or low [Phe] in numerous studies

1. Bilder DA et al. Dev Neuropscyhol. 2016;41:245-260. 2. Lee PJ et al. Neurosurg Psychiatry. 2009;80:631-635. 3. Marholin D et al. Pediatr Res. 1978;12:179-187. 4. ten Hoedt AE et al. J Inherit Metab Dis. 2011;34:165-171. 5. Bik-Multanowski M et al. J Inherit Metab Disord. 2008;31(suppl 2):S415-S418. 6. Brom MC, Guest JF. J Intellect Diabil Res. 1999;43:30-37. 7. Finkelson L et al. J Inherit Metab Dis. 2001:24:515-516. 8.Schuett VE et al. Am J Pub Health. 1985;75:39-42. 9. Yannicelli S, Ryan A. J Inherit Metab Dis. 1995;18:131-134. Psychiatric Symptoms in Adults With PKU1,2

Adults with PKU had increase Adult patients with PKU with in psychiatric symptoms compared positive screening for psychiatric with normative population symptoms had higher [Phe] a P < .05. 1. Bilder DA et al. Mol Genet Metab. 2013;108:155-160. 2. Burton BK et al. Mol Genet Metab. 2013;108:8-12. Psychiatric Outcomes in Adults With PKU1

a Control (n = 181) 40 37 a PKU (n = 35) 31 30

19 a a 20 16 14 14

Patients, % Patients, a 10 5 5 6 1 0 Depressed Phobias Generalized Hypochondriac Anxiety at Mood Anxiety Worries Work a P < .05 as compared with 18-year-old controls. 1. Pietz J et al. Pediatrics. 1997;99:345-350. Lower Phe Levels Associated With Better Executive Function in Adults1

Z-scores calculated with data from matching group of healthy controls. Higher Z-scores always indicate worse performance. a P < .05. b P < .01. 1. Romani C et al. Neuropsychology. 2017;31:242-254. High [Phe] Directly Affects Mood and Sustained Attention in Adults With PKU: Blinded Cross-Over Study1

• Adults with PKU were given Phe supplements (2.5 to 5 g/d based on weight and gender) or placebo for 4 weeks • This increased Phe levels from 709±322 to 1,209±332 mmol/L (P < .01)

1. ten Hoedt AE et al. J Inherit Metab Dis. 2011;34:165-171. Lower Blood [Phe] Levels Associated With Better Neuropsychiatric Outcomes1

Increase in [Phe] had negative effect on sustained attention, as well as on mood of patients

a P < .10. b P ≤ .05. c P ≤ .01. 1. ten Hoedt AE et al. J Inherit Metab Dis. 2011;34:165-171. Large Neutral Amino Acids (LNAAs) in the Treatment of PKU1

Compete with Phe for uptake LNAAs by membrane transporters

Histidine Isoleucine 0.1 to 1 g/kg/d suggested as an alternative Leucine treatment to improve cognitive outcome Lysine in patients with PKU Methionine Threonine LNAA might: Tryptophan 1. ↓ Brain [Phe] Tyrosine 2. ↓ Blood [Phe]a Valine 3. ↑ Brain neurotransmitter 4. ↑ Brain essential amino acids aOnly lysine-containing formulations 1. van Spronsen FJ et al. J Inherit Metab Dis. 2010;33:671-676. LNAA Supplementation Increases Melatonin Synthesis in PKU1

However, blood [Phe] levels in patients with PKU did not change significantly from placebo phase after supplementation with LNAA (P = .74)

1. Yano S et al. J Pediatr. 2013;162:999-1003. Effects of LNAA on the Function of Patients With PKU1

• Prospective, double blind, cross over study consisting of four 2-week phases with a 4-week washout period – Phase 1: usual medical product, protein-restricted diet, and 250 mg/kg/d LNAA (active) tablets – Phase 2: usual medical product, protein-restricted diet, and placebo tablets – Phase 3: no medical product, protein-restricted diet, and LNAA (active) tablets – Phase 4: no medical product, protein-restricted diet, and placebo tablets • At end of each phase, brain [Phe] and other metabolites measured by proton magnetic resonance spectroscopy (MRS) and plasma amino acids quantified – Detailed neuropsychological assessment performed on same day as MRS and plasma collection

1. Schindeler S et al. Mol Genet. 2007;91:48-54. Effects of LNAA on the Function of Patients With PKU1

• No significant difference in brain [Phe] between phases − For samples in phase 4 of study where plasma [Phe] was ≥1,200 μmol/L, there was a positive correlation (Spearman’s rs = 0.90; P = .04) • Better performances on attention measures when subjects were on standard medical product (phase 1 and 2) in comparison with off-standard medical product (phase 3 and 4) • Higher levels of anxiety symptoms also reported when on LNAA (phase 1 and 3) compared with off LNAA (phase 2 and 4)

1. Schindeler S et al. Mol Genet. 2007;91:48-54. 1 Comparison of Theoretical and Experimental Glycomacropeptide Amino Acid Contents of GMP

Amino Amino Theoretical Experimental Theoretical Experimental Acid Acid Glycomacropeptide (GMP) Trp 0.00 0.00 His 0.00 0.30 C-terminal part (f 106-169) of κ-casein, Phe 0.00 0.50 Lys 5.59 5.90 which is released in whey during cheese making by the action of chymosin. Tyr 0.00 0.10 Met 1.89 1.80 Leu 1.70 2.60 Pro 11.73 12.50 Val 9.00 8.00 Ser 8.04 6.10 Ile 10.00 10.10 Threo 18.23 15.80 Ala 5.68 5.50 Asp 3.39 8.60 Arg 0.00 0.50 Asn 5.05 0.00 Cys 0.00 0.10 Glu 15.01 20.50 Gly 0.96 1.10 Gln 3.73 0.00

Amino Acid Theoretical Experimental Total 100.00 100.00 BCAA 20.70 20.70 1. Badawy A. Psychopharmacology (Berl). 2013;228:347-358. GMP for Nutritional Management of PKU: A Randomized Controlled Crossover Trial1

[Phe] remains the same with GMP, but provides advantages in taste, convenience, and reduced GI AEs

1. Ney DM et al. Am Clin J Nutr. 2016;104:334-345. Summary

• Adults with PKU can have psychiatric and other symptoms that can be reduced by decreasing [Phe] • As such, adults with PKU should still be treated with diet, but dietary supplementation may improve adherence and or lessen restrictions – These include the use of LNAA and GMP-based supplements • Treatment should be individualized based on patient adherence to diet, blood [Phe], and the presence and severity of neuropsychiatric symptoms Adjunctive Pharmacologic Approaches What Are the Potential Implications for Relaxing Dietary Restrictions and Improving Neurocognitive Symptoms in Adults With PKU?

• Approved – Sapropterin

• In later stage of clinical development – Pegvaliase

• In early stage of clinical development Tetrahydrobioptern (BH4): An Important Cofactor in Phe Metabolism1

1. Thony B, Auerbach G, Blau N. Biochem J. 2000;347:1-16. 1-4 Sapropterin: Pharmacologic Form of BH4

• Approved by FDA in 2007 • Approximately 25%-50% of patients with PAH deficiency are sapropterin responsive – Patients with mild-moderate PAH deficiency most likely to respond; some stable protein is required for sapropterin to function Sapropterin – However, responsive patients have been identified among those with complete PAH deficiency

Current guidelines recommend that every PAH-deficient patient should be offered a trial of sapropterin therapy to assess responsiveness except those with two null mutations in trans5

1. Levy HL et al. Lancet. 2007;370:504-510. 2. Ziesch B et al. J Inherit Metab Dis. 2012;35:983-992. 3. Leuret O et al. J Inherit Metab Dis. 2012;35:975-981. 4. Utz JR et al. Mol Genet Metab. 2012;105:193-197. 5. Vockley J et al. Genet Med. 2014;16:188-200. Sapropterin: Dosing Considerations1

Available Dosage Forms Safety and Tolerability • Tablets: 100 mg • Excellent safety profile with • Powder for oral solution: 100 mg, 500 mg minimal side effects in clinical practice Starting Dosea • Most common AEs • Patients 1 mo to 6 years: 10 mg/kg 1x/d (incidence ≥ 4%): • Patients 7 years and older: 10-20 mg/kg 1x/d − Headache − Rhinorrhea a − Pharyngolaryngeal pain Dose Adjustment − Diarrhea • Doses may be adjusted in the range of − Vomiting 5-20 mg/kg 1x/d based on patient response − Cough • Blood [Phe] must be monitored regularly − Nasal congestion a20 mg/kg most commonly used dose used for initiation and maintenance2,3 1. Kuvan (sapropterin dihydrchloride) Prescribing Information. http://www.kuvan.com/hcp/wp-content/file/KUVAN _Prescribing_Information1.pdf. Accessed March 22, 2018.2. Gordon P et al. Mol Genet Metab. 2012;105:672-676. 3. Cunningham Mole Genet Metab 2012;106:269-276. Practical Considerations for Sapropterin

Initiation of sapropterin does not eliminate need for dietary

management; most patients with BH4-responsive PKU still require dietary restriction to maintain [Phe] in recommended range1

A subset of patients with milder forms of PKU can be adequately controlled on sapropterin alone

Data to be presented at 2018 ACMG meeting

1. Kuvan (sapropterin dihydrchloride) Prescribing Information. http://www.kuvan.com/hcp/wp-content/file/KUVAN _Prescribing_Information1.pdf. Accessed March 22, 2018. Executive Function Deficits Are Evident in Diet-Treated Patients of All Ages1-4

The following executive function deficits have been observed: • Working memory • Impulse control • Behavioral inhibition • Attentional flexibility

1. Diamond A et al. Monogr Soc Res Child Dev. 1997;62:1-208.2. Huijbregts SC et al. Neuropsychology. 2003:17:369-379. 3. White DA et al. J Int Neuropsycholog Soc. 2002; 8:1-11. 4. Channon S et al. Neuropsychology. 2004;4:613-620. PKU ASCEND Study: How Does Sapropterin Impact Executive Function?1

Double-Blind RCT of Sapropterin to Treat ADHD Symptoms and Executive Function Impairment in Children and Adults With Sapropterin-Responsive PKU ADHD RS/ASRS Total Score ADHD RS/ASRS Inattention Subscale Score

a P < .05 for improvement in sapropterin group vs PBO (MMRM analysis of least squares mean). 1. Burton BK et al. Mol Genet Metab. 2015:114:415-424. Enzyme-Substitution Therapy for PKU: Phenylalanine Ammonia Lyase (PAL)1

PAL • Phe-metabolizing enzyme found in many plants, several fungi, and bacteria • Requires no exogenous cofactor

NH Low 3 toxicity Ammonia Rapid conversion & Urinary excretion Phenylalanine Cinnamic Acid

1. Hoskins JA et al. Biomed Mass Spectrom. 1984;11:296-300. Pegvaliase: PEGylated PAL1

Recombinant Anabaena variabilis PAL (rAV-PAL) rAvPAL Pegvaliase (rAvPAL-PEG) PEGylation

Intended to (partially) mask antibody binding sites on PAL Monomer (Mw 64,000) ~ 150,000 atoms (MW 1,200,000) • Potential enzyme substitution therapy to decrease blood [Phe]; under investigation for the treatment of adults with PKU

1. Longo N et al. Lancet. 2014;384:37-44. Pegvaliase Clinical Development

• Injectable therapy; can be administered subcutaneously at home by patient or partner – Fixed dosing using prefilled syringes • Lengthy development period with multiple phase 2 trials – Many different dosing regimens explored  Most patients will require 1-2 injections daily – Evaluation of strategies to mitigate hypersensitivity reactions and risk of anaphylaxis • Culminated in a phase 3 trial involving a placebo-controlled, randomized discontinuation trial – 35 clinics in US participated • BLA under review by FDA; decision expected May 2018 PRISM-1: Phase 3, Open-Label, Randomized Trial of Fixed-Dose Pegvaliase in Adults With PKU

PRISM-1: Phase 3 Clinical Trial of Pegvaliase

Adult patients 2.5 mg weekly 20 mg daily 20 mg daily with blood Phe >600 µmol/L 2.5 mg weekly 40 mg daily 40 mg daily

Screening Induction Upward Titration Maintenance of Patients randomized Set dose Until target dose Target Dose 1:1 to maintenance 4 weeks achieved from week 5 At least 3 weeks target dose of 20 mg up to week 34 or 40 mg daily • PRISM-1 patients treated with pegvaliase to target maintenance dose in preparation to enter phase 3 PRISM-2 study

1. Longo N et al. 2016 Genetic Metabolic Dieticians International Meeting (GDMI 2016). Poster 23. PRISM-2: Pivotal Phase 3, Placebo-Controlled Randomized Discontinuation Trial in Adults With PKU1

PRISM-2: Pivotal Study of Pegvaliase With Randomized Discontinuation Trial (RDT)

20 mg daily 20 mg daily 20 mg daily Placebo 5 to 60 mg daily 40 mg daily 40 mg daily 40 mg daily Placebo Long-Term, ≥20% Blood Phe RDT PK and PD Open-Label Reduction From Randomized 2:1 6 weeks Extension Entry Into PRISM-1 8 weeks Dosing to individual 13 weeks efficacy targets 212 weeks Part 1 Part 2 Part 3 Part 4

1. Longo N et al. GDMI 2016. Poster 23. Change in Blood [Phe] With Pegvaliase1-2

Placebo Pegvaliase

[Phe] <360 μmol/L /L 2,000 P < .0001 by 6 mo

mol 1,460 1,385

μ 1,500 1,284 1,318 29% ], ], 1,000

Phe [Phe] <360 μmol/L 536 503 534 527 500 by 12 mo

Mean Observed Observed Mean 46%

Blood [ Blood 0 PRISM-1 PRISM-2 PRISM-2 PRISM-2 Pre-Tx RDT RDT RDT [Phe] <360 μmol/L Baseline Baseline Wk 4 Wk 8 by 24 mo 62% 53% had blood [Phe] <120 μmol/L by 24 mo

1. Harding C et al. J Inherit Metab Dis. 2016;39:S107. 2. Harding C et al. ACMG 2017. Abstract 822. Pegvaliase: Adverse Events1

Total Pegvaliase Daily Dose Adverse Effects, % <20 mg 20 to <40 mg Any 98 81 Related to study drug 97 72 Cause study discontinuation 3 <1 Generalized skin reaction (≥14-day duration) 9 11 Arthralgia 52 35 Injection site reaction 82 42 Injection-site skin reaction (≥14-day duration) 20 8 Hypersensitivity AE 78 58 Anaphylaxis (NIAD/FAAN Criteria) 2 4 Anaphylaxis (Brown’s Severe Criteria) <1 <1

1. Longo N et al. GDMI 2016. Poster 23. Pegvaliase: Safety Summary1,2

• Hypersensitivity reactions are very common; premedication with H1 and H2 blockers and ibuprofen required

• Patients cannot be started on an effective dose; a period of induction and titration required

– During this time, a significant impact on blood [Phe] not expected

• Although rare, anaphylactic reactions possible; patients must have epinephrine auto-injector

1. Harding C et al. J Inherit Metab Dis. 2016;39:S107. 2. Harding C et al. ACMG 2017. Abstract 822. PRISM-2 RDT: Neurocognitive Impact of Pegvaliase Treatment1,2

• Inattention, anxiety, and depression were assessed, and no statistically significant differences were observed • Patients on long-term open-label pegvaliase showed significant improvement in inattention scores (ADHD-RS) • Functional tests of executive function (CANTAB) showed a trend toward improvement in a small number of patients studied

1. Harding C et al. J Inherit Metab Dis. 2016;39:S107. 2. Harding C et al. ACMG 2017. Abstract 822. Challenges in Assessing Neurocognitive Function in PKU and Relationship to Treatment

Very heterogeneous patient population with variable symptoms and variable metabolic control

Many of the instruments used are self-report, and poor self-awareness is characteristic of the PKU phenotype

Improvement in many domains may take a long time and may not be captured in short-term clinical trials PRISM-1 and PRISM-2: Blood [Phe] and ADHD1

Mean (SD) Blood [Phe] and Investigator-Rated ADHD-RS Inattention Over Time From PRISM-1 Pretreatment Baseline to PRISM-2 Long-Term Extension

1. Longo N et al. GDMI 2016. Poster 23. Future Prospects for Adjunctive Pharmacologic Therapy for PKU Management1,2

Probiotics that metabolize Phe before absorbed

Oral PAL

Erythrocyte-mediated delivery of PAL

Enzyme replacement therapy with PAH

Liver-directed gene therapy

1. Al Hafid N, Christodoulou.J. Transl Pediatr. 2015;4:304-317. 2. Sumaily KM, Mujamammi AH. Int J Health Sci (Qassim). 2017;11:63-70. Summary

• Current guidelines recommend that every PAH-deficient patient should be offered a trial of sapropterin therapy to assess responsiveness, except those with two null mutations in trans – Patients with mild-moderate PAH deficiency most likely to respond; some stable protein is required for sapropterin to function – However, responsive patients have been identified among those with complete PAH deficiency

• Clinical trial data support enzyme substitution therapy with pegvaliase as a viable approach for lowering blood [Phe] in adult patients with PKU and may provide patients with a new option that may permit easing of dietary restrictions Conclusions

• Newborn screening programs along with prompt institution of a low-Phe diet successfully prevents intellectual disability in early treated PKU patients • However, dietary compliance remains a major issue as patients approach adolescence and adulthood, resulting in poor blood [Phe] control and leading to suboptimal outcomes in psychosocial and cognitive outcomes • Contrasting data have been generated from studies using LNAA as an alternative to dietary therapy; it has been only recommended for adult PKU patients who do not adhere to the diet Conclusions (Cont’d)

• The incorporation of GMP into low-Phe diet has improved palatability, variety, and convenience of the diet and provides a more physiological form of amino acid to be consumed by PKU patients • Sapropterin and the emerging therapy pegvaliase offer the opportunity to substantially lower blood [Phe] and potentially ease dietary restrictions in patients with PKU • As such, any combination of therapies that facilitates improvement in blood [Phe] levels for a given patient with PKU is appropriate; treatment should be individualized Please remember to complete and submit your Post-Test and Evaluation for CME credit. Missed anything?

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Thank you and good evening.