PRX-102 for treating Fabry disease: immunogenicity and PK results from a phase 1-2 study

Abstracts / Molecular Genetics and Metabolism 120 (2016) S17–S145 outcome. (This work is part of our lysosome storage disease research project and quality improvement study. Sponsored by Pfizer/ACMG 2016 Fellowship Award and Resident Research Award from OUHSC Children’s Hospital Research Foundation.) doi:10.1016/j.ymgme.2016.11.361 353 Different ARSB variants causing mucopolysaccharidosis type VI in dogs Ping Wang, Carol Margolis, Gloria Lin, Karthik Raj, Rachel Han, Lisa Berman, Polly Foureman, Adrian Sewell, Urs Giger, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States Mucopolysaccharidoses (MPS) type VI (Maroteaux-Lamy disease, OMIM # 253200) caused by a severe deficiency of arylsulphatase B (ARSB, EC 3.1.6.12) has been reported in human patients and companion animals. MPS VI affected animals (OMIA # 000666) show clinical signs of stunted growth, facial dysmorphia, skeletal deformities, organ enlargements and corneal opacities similar to humans. As part of the NIH National Referral Center for Animal Models of Human Genetic Disease (NIH OD 010939), we describe here the biochemical and molecular characterization of MPS VI in different breeds of dogs. Clinically affected dogs showed many metachromatic granules in leukocytes and a strongly positive urinary mucopolysaccharide spot test due to excessive dermatan sulfate excretion. Tested leukocytes, fibroblasts and/or liver tissue revealed a complete absence of ARSB activity. The ARSB coding and adjacent intronic regions were amplified and sequenced and the results were compared to the CanFam 3.1: CM000003.3 and NCBI RefSeq# NM_001048133.1, and also the sequences from healthy dogs of the same breed. Affected dogs were found to be homozygous for a single base missense (SIFT deleterious) mutation, two polynucleotide deletions, and an early nonsense mutation in Miniature Pinschers, Miniature Schnauzers, Toy Poodles and Great Danes, respectively. Utilizing these breed-specific genomic variants, DNA tests were established to screen related dogs and breeds at the PennGen Laboratories of the School of Veterinary Medicine, University of Pennsylvania. Based upon screening results MPS VI is commonly found in Miniature Pinschers, and like in cats, dogs with MPS VI serve as valuable animal models for studying therapeutic safety and efficacy in human patients. doi:10.1016/j.ymgme.2016.11.362 354 Canine GM2-gangliosidosis (Sandhoff disease) caused by a 3 base pair deletion in the HEXB gene Ping Wang, Evelyn Galban, Paula S Henthorn, Gloria Lin, Teiko Takedai, Margret Casal, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States GM2-gangliosidosis type II (Sandhoff disease, O variant) is a fatal neurodegenerative lysosomal storage disease caused by mutations in the HEXB gene, coding for the beta subunit of β-hexosaminidase type A (HEX-A) and B (HEX-B). Deficiencies in HEX-A and HEX-B lead to accumulation of GM2 gangliosides in neurons and thus to neuronal dysfunction and degeneration. This study characterizes the S137 phenotype and genotype of a naturally occurring GM2-gangliosidosis in a Shiba Inu dog. A 14-month-old, female Shiba Inu presented with clinical signs of gradually decreasing coordination, difficulty ambulating as well as standing, and tremors. Neurologic evaluation demonstrated the presence of severe cerebellar ataxia, bilateral lack of menace response, and severe intention tremors. Blood smears revealed storage granules in leukocytes, and brain magnetic resonance images were indicative of a neurodegenerative disease. Lysosomal enzymes assays performed on plasma and leukocytes revealed a deficiency in the activities of both HEX-A and HEX-B. Sequencing of the HEXB gene identified a homozygous sequential 3base pair deletion in exon 7 (c.615_617delCCT), which predicts the loss of a leucine residue at amino acid position 206 (p.Leu206del). Protein structure modeling studies predict that the missing leucine could have a deleterious effect on the functional structures of the β subunit of HEX-A and HEX-B. Using this genetic variant as an informative molecular marker, an allelic discrimination real-time PCR based genotyping assay was established to detect the mutant allele. Two hundred clinically healthy dogs of various breeds were homozygous for the wild-type allele, suggesting that this is not a polymorphism in dogs but a unique, disease-causing mutation in the affected dog. This is the first Sandhoff GM2- gangliosidosis described in the Shiba Inu breed and only the second recognized genetic variation responsible for this disorder in dogs. doi:10.1016/j.ymgme.2016.11.363 355 PRX-102 for treating Fabry disease: immunogenicity and PK results from a phase 1-2 study David Warnocka, Derralynn Hughesb, Simeon Boydc, Pilar Giraldod, Derlis Gonzaleze, Myrl Holidaf, Ozlem Goker-Alpang, Gustavo Maegawah, Mohamed Attai, Kathy Nichollsj,k, Raphael Schiffmannl, Ahmad Tuffaham, Martha Charneyn, Raul Chertkoff o, Sari Alonp, Einat Brill-Almonp, aUAB, Birmingham, AL, United States, bUniversity Colege London, London, United Kingdom, cUC Davis Medical Center, Sacramento, CA, United States, dHospital de Dia Quiron, Zaragoza, Spain, eInstituto Privado De Hematologia Investigacion Clinica, Asuncion, Paraguay, f University of Iowa, Iowa City, IA, United States, gO&O Alpan LLC, Fairfax, VA, United States, hUniversity of Florida, Gainesville, FL, United States, i Johns Hopkins University School of Medicine, Baltimore, MD, United States, j Royal Melbourne Hospital, Melbourne, Australia, kThe University of Melbourne, PArkville, Australia, lBaylor University, Dallas, TX, United States, mKansas University Medical Center, Kansas City, KS, United States, n Pharmacokinetics Consultant, Toronto, ON, Canada, oProtalix, Carmiel, AL, United States, pProtalix, Carmiel, Israel PRX-102 is a novel, chemically modified, α-galactosidase A for the treatment of Fabry disease (FD). Immune responses to therapeutic protein could potentially impact its efficacy and-or safety. In FD, an X-linked disorder caused by the loss of function of the lysosomal enzyme α-galactosidase-A, anti-drug antibody (ADA) formation towards the enzyme has been shown to occur in a high percentage of male patients, especially with nonsense mutations. Immunogenicity and its impact on plasma PRX-102 pharmacokinetics (PK) was evaluated in 16 FD patients participating in a Phase 1/2 study of PRX-102 administered IV every 2 weeks in 3 cohorts (cohort 1, 2 and 3 received 0.2, 1.0 and 2.0 mg/kg PRX-102, respectively). Results: Immunogenicity: Three (3) male patients developed treatment induced IgG antibodies to PRX-102 (ADA +); two patients from Cohort 1 and one from Cohort 2. There were no ADA + patients in Cohort 3. All 3 ADA+ patients became negative in the second year of S138 Abstracts / Molecular Genetics and Metabolism 120 (2016) S17–S145 treatment, consistent with reduced immunogenicity and induced tolerance during PRX-102 treatment. Impact on PK: PRX-102 has a favorable PK profile [maximum concentration (Cmax) and overall enzyme amount (AUC)] with higher amount of active enzyme available throughout the 2-week treatment intervals. The 2 ADA + patients in Cohort 1 exhibited a distinct and reversible effect on PK profile resulting in decreased Cmax and AUC at 3 and 6 months compared to Day 1, with improvement back to the baseline profile after 12 months of treatment, suggesting that the ADA impact on PRX-102 activity was transient. The ADA + patient in Cohort 2 had a low ADA titer and had stable PK parameters throughout the study. In summary, it appears that the reduced immunogenicity of PRX-102 is associated with improved PK profiles that may reflect longer term induction of tolerance in previously seroconverted patients. 357 Consensus recommendation on a diagnostic guideline for acid sphingomyelinase deficiency Melissa Wassersteina, Carlo Dionisi-Vicib, Roberto Giuglianic, Paul Hwud, Olivier Lidovee, Zoltan Lukacsf, Eugen Mengelg, Pramod Mistryh, Edward Schuchmani, Margaret McGovernj, aChildren’s Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY, United States, b Hospital Bambino Gesu, Rome, Italy, cMedical Genetics Service, HCPA, Porto Alegre, Brazil, dNational Taiwan University Hospital, Taipei, Taiwan, e Hopital de la Croix St Simon, Paris, France, fUniversity Medical Center Hamburg-Eppendorf, Hamburg, Germany, gMedical Center of the Johannes Gutenberg University, Mainz, Germany, hYale University School of Medicine, New Haven, CT, United States, iIcahn School of Medicine at Mt. Sinai, New York, NY, United States, jStony Brook University School of Medicine, Stony Brook, NY, United States doi:10.1016/j.ymgme.2016.11.364 356 The New York pilot newborn screen for lysosomal diseases: 40 month data Melissa Wassersteina, Sean Baileyb, Michele Cagganac, Robert J Desnickd, Ian Holzmand, Nicole Kellya, Gabriel Kupchike, Monica Martinc, Randi Wassermanf, Amy Yangd, Joseph J Orsinic, aChildren's Hospital at Montefiore, Bronx, NY, United States, bNew York University Medical Center, New York, NY, United States, cNew York State Department of Health, Albany, NY, United States, dIcahn School of Medicine at Mount Sinai, New York, NY, United States, eMaimonides Medical Center, Brooklyn, NY, United States, fElmhurst Hospital Center, Queens, NY, United States A prospective, consented pilot study is currently underway at four New York City hospitals in order to assess the utility of newborn screening for lysosomal diseases, to define the pre-symptomatic natural history, and to evaluate the ethical, legal, and social issues associate with such screening. Between May 2013 and September 1, 2016, 49,996 of 68, 094 (73%) approached parents verbally consented to participate. Lysosomal disease testing is performed at the NYS NBS LSD Lab using tandem MS-MS to measure enzyme activity with referral cutoffs set to 15% of daily mean activity for GAA, IDUA, ABG, ASM, and 25% for GLA. 19,197 specimens were screened for Pompe between May 2013 and October 2014. Of 6 referred infants, 1 has genotype consistent with lateronset disease and 5 have pseudodeficiency alleles (PPV=0.17). 20,320 were screened for MPS I since it was added in May 2015. 5 of 5 referred infants are unaffected based on genotype (PPV=0). Of 49,996 infants screened for Fabry, Gaucher and Niemann-Pick disease type A/B: 10 of 16 referred Fabry disease infants have later-onset genotypes, 3 are negative, 1 was lost to follow-up and 2 results are pending (PPV=0.77); 9 of 11 infants who underwent confirmatory testing for Gaucher have genotypes consistent with later-onset disease, 1 is negative and 1 result is pending (PPV=0.9), and the 2 infants referred for Niemann-Pick disease type A/B have genotypes consistent with later-onset disease (PPV=1.0). In summary, we have detected only later-onset lysosomal diseases, which challenges traditional NBS criteria. NBS using enzyme activity alone results in a wide range of PPVs as defined by genotypes. Gaucher and Niemann-Pick disease type A/B have the highest PPVs, whereas MPS I and Pompe disease, the only two lysosomal diseases currently on the RUSP, have the lowest. Concurrent molecular analysis to reduce the number of false positives is recommended. doi:10.1016/j.ymgme.2016.11.365 Acid sphingomyelinase deficiency (ASMD) is a rare, progressive, multiorgan lysosomal disease historically known as Niemann-Pick disease types A (NPD A) and B (NPD B). ASMD results in the progressive accumulation of sphingomyelin in reticuloendothelial organs (liver, spleen, bone marrow, and lung), hepatocytes, and in severe cases, brain. ASMD manifests as a clinical spectrum ranging from a rapidly progressive infantile neurovisceral form (NPD A) which is uniformly fatal by age 3, to chronic neurovisceral (NPD B variant) and visceral (NPD B) forms that have variable ages of onset, slower progression, and longer lifespans. Disease management is aimed at mitigating symptoms and regular assessments for multisystem involvement. An international panel of laboratory and clinical ASMD experts gathered to review the evidence base and develop guidelines for the diagnosis, nomenclature, and management of ASMD. During a meeting at which published material and personal experience were reviewed, the panel members discussed the best approach for diagnosis and developed a diagnostic guideline and new recommended nomenclature to better capture the clinical spectrum of ASMD. The diagnosis of ASMD is based on ASMD enzyme activity and SMPD1 gene sequencing. Because of symptom overlap between ASMD and Gaucher disease, it is recommended that, whenever possible, parallel enzyme testing for Gaucher disease and ASMD is performed. Although care of ASMD patients is typically provided by metabolic disease specialists, the guideline is directed at a wide range of providers since it is important that primary care providers (e.g., pediatricians) and specialists (e.g., pulmonologists, hepatologists, and hematologists) be able to recognize ASMD in order to provide the appropriate patient care and referrals. Early diagnosis is essential for effective disease and symptom management. (Supported by Sanofi Genzyme.) doi:10.1016/j.ymgme.2016.11.366 358 Genistein: a lysosomal stimulator for treatment of various lysosomal diseases Grzegorz Wegrzyna, Karolina Pierzynowskaa, Aleksandra Haca, Magdalena Gabig-Ciminskab, Joanna Jakobkiewicz-Baneckaa, aUniversity of Gdansk, Gdansk, Poland, bInstitute of Biochemistry and Biophysics of Polish Academy of Sciences, Gdansk, Poland The use of genistein (5, 7-dihydroxy-3- (4-hydroxyphenyl)-4H-1benzopyran-4-one) has been proposed as a putative treatment for lysosomal diseases, particularly mucopolysaccharidoses (MPS). This proposal was based on findings that this isoflavone can inhibit