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Tam A, Chen S, Schauer E, Grafe I, Bandi V, Shapiro JR, Steiner RD, Smith PA, Bober MB, Hart T, Cuthbertson D, Krischer J, Mullins M, Byers PH, Sandhaus RA, Durigova M, Glorieux FH, Rauch F, Sutton VR, Lee B, Rush ET, Nagamani SCS. A multicenter study to evaluate pulmonary function in osteogenesis imperfecta. Clin Genet 2018; 94:502-511. [PMID: 30152014 PMCID: PMC6235719 DOI: 10.1111/cge.13440] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 01/04/2023]
Abstract
Pulmonary complications are a significant cause for morbidity and mortality in osteogenesis imperfecta (OI). However, to date, there have been few studies that have systematically evaluated pulmonary function in individuals with OI. We analyzed spirometry measurements, including forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1 ), in a large cohort of individuals with OI (n = 217) enrolled in a multicenter, observational study. We show that individuals with the more severe form of the disease, OI type III, have significantly reduced FVC and FEV1 which do not follow the expected trends of the normal population. We also show that "normalization" of FVC and FEV1 using general population data to generate percent predicted values underestimates the pulmonary involvement in OI. Within each subtype of OI, we used linear mixed models to find potential correlations between FEV1 and FVC with the clinical variables including mobility, bisphosphonate use, and scoliosis. Our results are an important step in understanding the extent of pulmonary involvement in individuals with OI and for developing pulmonary endpoints for use in the routine patient care as well as in the investigation of new therapies.
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Affiliation(s)
- Allison Tam
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Shan Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Evan Schauer
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Ingo Grafe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Venkata Bandi
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Jay R Shapiro
- Department of Bone and Osteogenesis Imperfecta, Kennedy Krieger Institute, Baltimore, MD, USA
- Department of Medicine at Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Robert D Steiner
- University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Oregon Health & Science University, and Shriners Hospital for Children, Portland, OR USA
| | | | - Michael B Bober
- Division of Medical Genetics, Alfred I du Pont Hospital for Children, Wilmington, DE, USA
| | - Tracy Hart
- Osteogenesis Imperfecta Foundation, Gaithersburg, MD, USA
| | | | - Jeff Krischer
- College of Medicine, University of South Florida, Tampa, FL, USA
| | - Mary Mullins
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Peter H Byers
- Departments of Medicine and Pathology, Division of Medical Genetics, University of Washington, Seattle, WA, USA
| | | | | | | | - Frank Rauch
- Shriner’s Hospital for Children and McGill University, Montreal
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
| | | | - Eric T Rush
- Children’s Mercy Hospital, University of Missouri - Kansas City, Kansas City, MO, USA
| | - Sandesh CS Nagamani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
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2
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Lee JS, Carmel N, Karathia H, Auslander N, Rabinovich S, Keshet R, Stettner N, Silberman A, Agemy L, Helbling D, Eilam R, Sun Q, Brandis A, Weiss H, Dimmock D, Stern-Ginossar N, Scherz A, Ulitsky I, Nagamani SCS, Elhasid R, Hannenhalli S, Ruppin E, Erez A. Abstract A69: Mutagenicity of urea cycle dysregulation and its implications for cancer immunotherapy. Cancer Immunol Res 2018. [DOI: 10.1158/2326-6074.tumimm17-a69] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Immune checkpoint therapy leads to durable clinical responses in many cancer patients, but fails in others. To improve the clinical response to immunotherapy, it is highly important to identify predictive biomarkers. While checkpoint genes’ expression levels, tumor neo-antigen load and microsatellite instability (MSI) have been associated with enhanced response to checkpoint immunotherapies, they yet provide only a modest predictive signal and hence there is a need to identify additional predictive factors. Specifically, while there is growing evidence that metabolic alterations can affect the tumor and modulate the immune response, the potential effects of altered cancer metabolism on tumor mutagenesis and immunotherapy remain unexplored.
The urea cycle (UC) converts excess nitrogen derived from the breakdown of nitrogen-containing molecules (e.g., ammonia) to urea, a relatively non-toxic and disposable nitrogenous compound. We and others have shown that silencing of the UC enzyme ASS1 promotes cancer proliferation by diverting its substrate aspartate toward CAD enzyme, which mediates the first three reactions in the pyrimidine synthesis pathway. We now demonstrate, by analysis of the TCGA data, tumor samples and cancer cell line experiments, that UC dysregulation (UCD) is a much wider common metabolic phenomenon that maximizes nitrogen utilization in cancer, favoring pyrimidine synthesis over urea disposal. Of note, while UCD is significantly associated with decreased cancer patient survival, the overall mutational load is not.
Remarkably, we find that the UCD changes the 1:1 purine (R)-to-pyrimidine (Y) ratio in favor of pyrimidine in cancer cells. Moreover, in analysis of both TCGA data and UC perturbed cancer cells we find that: (a) UCD is significantly associated with a novel and unique pattern of purine-to-pyrimidine transversion mutational bias across many cancer types at the DNA coding (sense) strand, and (b) this trend becomes stronger and more significant at both the mRNA and protein levels, testifying to its functional implications. Notably, the overall mutational load in cancer is negatively correlated with UCD, testifying to their independence.
To test whether the mutational bias is associated with better immunotherapy response, we analyze published data of three large melanoma cohorts. We find that responders of both anti-PD1 and anti-CTLA4 therapy exhibit significantly higher UCD and R->Y mutational bias than non-responders. We further observe that the peptides carrying transverse R->Y mutations are preferentially presented as neoantigens in responders independent of mutational load, and this trend becomes significant for more clonal neoantigens, promoting UCD as a potential biomarker for the success of immunotherapy.
Finally, as nitrogen metabolites are excreted in the urine, we hypothesize that these changes may be detectable in urine of UCD-cancers. We observe increased levels of pyrimidine derived metabolites in the urine of mice bearing colon tumors associated with UCD in the tumors compared to normal intestine. In an analogous manner, we find significantly higher levels pyrimidine derived metabolites in the urine of human patients with prostate cancer compared to controls.
Collectively, these results support our hypothesis that UCD is a prevalent metabolic phenomenon in cancer, generating mutational biased neo-peptides, worsening patients’ prognosis and yet enhancing the response to immune therapy independent of mutational load and MSI. Taken together, our findings point to the important role of UCD in a broad spectrum of cancers, to the potential use of UCD related metabolites as cancer biomarkers, and last but not least, to the role of UCD in predicting response to immune check point therapy. Broadly, our results suggest future therapeutic interventions aiming to increase UCD levels to enhance the coverage and efficiency of cancer immunotherapy.
Citation Format: Joo Sang Lee, Narin Carmel, Hiren Karathia, Noam Auslander, Shiran Rabinovich, Rom Keshet, Noa Stettner, Alon Silberman, Lilach Agemy, Daniel Helbling, Raya Eilam, Qin Sun, Alexander Brandis, Hila Weiss, David Dimmock, Noam Stern-Ginossar, Avigdor Scherz, Igor Ulitsky, Sandesh CS Nagamani, Ronit Elhasid, Sridhar Hannenhalli, Eytan Ruppin, Ayelet Erez. Mutagenicity of urea cycle dysregulation and its implications for cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A69.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Qin Sun
- 4Baylor College of Medicine, Houston, TX,
| | | | | | - David Dimmock
- 5University of California, San Diego, San Diego, CA,
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3
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Marini JC, Agarwal U, Didelija IC, Azamian M, Stoll B, Nagamani SCS. Plasma Glutamine Is a Minor Precursor for the Synthesis of Citrulline: A Multispecies Study. J Nutr 2017; 147:549-555. [PMID: 28275102 PMCID: PMC5368584 DOI: 10.3945/jn.116.243592] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/10/2017] [Accepted: 02/10/2017] [Indexed: 01/21/2023] Open
Abstract
Background: Glutamine is considered the main precursor for citrulline synthesis in many species, including humans. The transfer of 15N from 2-[15N]-glutamine to citrulline has been used as evidence for this precursor-product relation. However, work in mice has shown that nitrogen and carbon tracers follow different moieties of glutamine and that glutamine contribution to the synthesis of citrulline is minor. It is unclear whether this small contribution of glutamine is also true in other species.Objective: The objective of the present work was to determine the contribution of glutamine to citrulline production by using nitrogen and carbon skeleton tracers in multiple species.Methods: Humans (n = 4), pigs (n = 5), rats (n = 6), and mice (n = 5) were infused with l-2-[15N]- and l-[2H5]-glutamine and l-5,5-[2H2]-citrulline. The contribution of glutamine to citrulline synthesis was calculated by using different ions and fragments: glutamine M+1 to citrulline M+1, 2-[15N]-glutamine to 2-[15N]-citrulline, and [2H5]-glutamine to [2H5]-citrulline.Results: Species-specific differences in glutamine and citrulline fluxes were found (P < 0.001), with rats having the largest fluxes, followed by mice, pigs, and humans (all P < 0.05). The contribution of glutamine to citrulline as estimated by using glutamine M+1 to citrulline M+1 ranged from 88% in humans to 46% in pigs. However, the use of 2-[15N]-glutamine and 2-[15N]-citrulline as precursor and product yielded values of 48% in humans and 28% in pigs. Furthermore, the use of [2H5]-glutamine to [2H5]-citrulline yielded lower values (P < 0.001), resulting in a contribution of glutamine to the synthesis of citrulline of ∼10% in humans and 3% in pigs.Conclusions: The recycling of the [15N]-glutamine label overestimates the contribution of glutamine to citrulline synthesis compared with a tracer that follows the carbon skeleton of glutamine. Glutamine is a minor precursor for the synthesis of citrulline in humans, pigs, rats, and mice.
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Affiliation(s)
- Juan C Marini
- Section of Critical Care Medicine, .,USDA/Agricultural Research Service, Children's Nutrition Research Center, and
| | - Umang Agarwal
- USDA/Agricultural Research Service, Children’s Nutrition Research Center, and
| | - Inka C Didelija
- USDA/Agricultural Research Service, Children’s Nutrition Research Center, and
| | - Mahshid Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - Barbara Stoll
- USDA/Agricultural Research Service, Children’s Nutrition Research Center, and
| | - Sandesh CS Nagamani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
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4
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Lee B, Diaz GA, Rhead W, Lichter-Konecki U, Feigenbaum A, Berry SA, Le Mons C, Bartley J, Longo N, Nagamani SC, Berquist W, Gallagher RC, Harding CO, McCandless SE, Smith W, Schulze A, Marino M, Rowell R, Coakley DF, Mokhtarani M, Scharschmidt BF. Glutamine and hyperammonemic crises in patients with urea cycle disorders. Mol Genet Metab 2016; 117:27-32. [PMID: 26586473 PMCID: PMC4915945 DOI: 10.1016/j.ymgme.2015.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/10/2015] [Accepted: 11/10/2015] [Indexed: 12/30/2022]
Abstract
UNLABELLED Blood ammonia and glutamine levels are used as biomarkers of control in patients with urea cycle disorders (UCDs). This study was undertaken to evaluate glutamine variability and utility as a predictor of hyperammonemic crises (HACs) in UCD patients. METHODS The relationships between glutamine and ammonia levels and the incidence and timing of HACs were evaluated in over 100 adult and pediatric UCD patients who participated in clinical trials of glycerol phenylbutyrate. RESULTS The median (range) intra-subject 24-hour coefficient of variation for glutamine was 15% (8-29%) as compared with 56% (28%-154%) for ammonia, and the correlation coefficient between glutamine and concurrent ammonia levels varied from 0.17 to 0.29. Patients with baseline (fasting) glutamine values >900 μmol/L had higher baseline ammonia levels (mean [SD]: 39.6 [26.2]μmol/L) than patients with baseline glutamine ≤ 900 μmol/L (26.6 [18.0]μmol/L). Glutamine values >900 μmol/L during the study were associated with an approximately 2-fold higher HAC risk (odds ratio [OR]=1.98; p=0.173). However, glutamine lost predictive significance (OR=1.47; p=0.439) when concomitant ammonia was taken into account, whereas the predictive value of baseline ammonia ≥ 1.0 upper limit of normal (ULN) was highly statistically significant (OR=4.96; p=0.013). There was no significant effect of glutamine >900 μmol/L on time to first HAC crisis (hazard ratio [HR]=1.14; p=0.813), but there was a significant effect of baseline ammonia ≥ 1.0 ULN (HR=4.62; p=0.0011). CONCLUSIONS The findings in this UCD population suggest that glutamine is a weaker predictor of HACs than ammonia and that the utility of the predictive value of glutamine will need to take into account concurrent ammonia levels.
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Affiliation(s)
- B Lee
- Baylor College of Medicine, Houston, TX, USA.
| | - G A Diaz
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - W Rhead
- The Medical College of Wisconsin, Milwaukee, WI, USA
| | | | | | - S A Berry
- Univ. of Minnesota, Minneapolis, MN, USA
| | - C Le Mons
- National Urea Cycle Disorders Foundation, Pasadena, CA, USA
| | - J Bartley
- Miller Children's Hospital, Long Beach, CA, USA
| | - N Longo
- Univ. of UT, Salt Lake City, UT, USA
| | | | | | | | | | - S E McCandless
- Case Western Reserve Univ. Medical Center, Cleveland, OH, USA
| | - W Smith
- Maine Medical Ctr., Portland, ME, USA
| | - A Schulze
- The Hospital for Sick Children, Univ. of Toronto, Canada
| | - M Marino
- Oregon Health Sciences, Portland, OR, USA
| | - R Rowell
- MED Technical Consulting, Inc., Union City, CA, USA
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5
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Bellur S, Jain M, Cuthbertson D, Krakow D, Shapiro JR, Steiner RD, Smith PA, Bober MB, Hart T, Krischer J, Mullins M, Byers PH, Pepin M, Durigova M, Glorieux FH, Rauch F, Sutton VR, Lee B, Nagamani SC. Cesarean delivery is not associated with decreased at-birth fracture rates in osteogenesis imperfecta. Genet Med 2015; 18:570-6. [PMID: 26426884 PMCID: PMC4818203 DOI: 10.1038/gim.2015.131] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 08/14/2015] [Indexed: 11/18/2022] Open
Abstract
Purpose Osteogenesis imperfecta (OI) predisposes to recurrent fractures. The moderate-to-severe forms of OI present with antenatal fractures and the mode of delivery that would be safest for the fetus is not known. Methods We conducted systematic analyses on the largest cohort of individuals (n=540) with OI enrolled to-date in the OI Linked Clinical Research Centers. Self-reported at-birth fracture rates were compared in individuals with OI types I, III, and IV. Multivariate analyses utilizing backward-elimination logistic regression model building were performed to assess the effect of multiple covariates including method of delivery on fracture-related outcomes. Results When accounting for other covariates, at-birth fracture rates did not differ based on whether delivery was by vaginal route or by cesarean section (CS). Increased birth weight conferred higher risk for fractures irrespective of the delivery method. In utero fracture, maternal history of OI, and breech presentation were strong predictors for choosing CS for delivery. Conclusion Our study, the largest to analyze the effect of various factors on at-birth fracture rates in OI shows that delivery by CS is not associated with decreased fracture rate. With the limitation that the fracture data were self-reported in this cohort, these results suggest that CS should be performed only for other maternal or fetal indications, but not for the sole purpose of fracture prevention in OI.
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Affiliation(s)
- S Bellur
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - M Jain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - D Cuthbertson
- College of Medicine, University of South Florida, Tampa, Florida, USA
| | - D Krakow
- Department of Orthopedic Surgery, University of California, Los Angeles, California, USA.,Department of Human Genetics, University of California, Los Angeles, California, USA.,Department of Obstetrics and Gynecology, University of California, Los Angeles, California, USA
| | - J R Shapiro
- Department of Bone and Osteogenesis Imperfecta, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - R D Steiner
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA.,Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon, USA.,Marshfield Clinic Research Foundation and University of Wisconsin, Marshfield and Madison, Wisconsin, USA
| | - P A Smith
- Shriners Hospitals for Children, Chicago, Illinois, USA
| | - M B Bober
- Division of Medical Genetics, Alfred I. DuPont Hospital for Children, Wilmington, Delaware, USA
| | - T Hart
- Osteogenesis Imperfecta Foundation, Gaithersburg, Maryland, USA
| | - J Krischer
- College of Medicine, University of South Florida, Tampa, Florida, USA
| | - M Mullins
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - P H Byers
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington, USA.,Department of Pathology, Division of Medical Genetics, University of Washington, Seattle, Washington, USA
| | - M Pepin
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington, USA.,Department of Pathology, Division of Medical Genetics, University of Washington, Seattle, Washington, USA
| | - M Durigova
- Department of Orthopedic Surgery, Shriners Hospital for Children and McGill University, Montreal, Québec, Canada
| | - F H Glorieux
- Department of Orthopedic Surgery, Shriners Hospital for Children and McGill University, Montreal, Québec, Canada
| | - F Rauch
- Department of Orthopedic Surgery, Shriners Hospital for Children and McGill University, Montreal, Québec, Canada
| | - V R Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
| | - B Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
| | | | - S C Nagamani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
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Mokhtarani M, Diaz GA, Rhead W, Berry SA, Lichter-Konecki U, Feigenbaum A, Schulze A, Longo N, Bartley J, Berquist W, Gallagher R, Smith W, McCandless SE, Harding C, Rockey DC, Vierling JM, Mantry P, Ghabril M, Brown RS, Dickinson K, Moors T, Norris C, Coakley D, Milikien DA, Nagamani SC, Lemons C, Lee B, Scharschmidt BF. Elevated phenylacetic acid levels do not correlate with adverse events in patients with urea cycle disorders or hepatic encephalopathy and can be predicted based on the plasma PAA to PAGN ratio. Mol Genet Metab 2013; 110:446-53. [PMID: 24144944 PMCID: PMC4108288 DOI: 10.1016/j.ymgme.2013.09.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 09/29/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Phenylacetic acid (PAA) is the active moiety in sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB, HPN-100). Both are approved for treatment of urea cycle disorders (UCDs) - rare genetic disorders characterized by hyperammonemia. PAA is conjugated with glutamine in the liver to form phenylacetyleglutamine (PAGN), which is excreted in urine. PAA plasma levels ≥ 500 μg/dL have been reported to be associated with reversible neurological adverse events (AEs) in cancer patients receiving PAA intravenously. Therefore, we have investigated the relationship between PAA levels and neurological AEs in patients treated with these PAA pro-drugs as well as approaches to identifying patients most likely to experience high PAA levels. METHODS The relationship between nervous system AEs, PAA levels and the ratio of plasma PAA to PAGN were examined in 4683 blood samples taken serially from: [1] healthy adults [2], UCD patients of ≥ 2 months of age, and [3] patients with cirrhosis and hepatic encephalopathy (HE). The plasma ratio of PAA to PAGN was analyzed with respect to its utility in identifying patients at risk of high PAA values. RESULTS Only 0.2% (11) of 4683 samples exceeded 500 μg/ml. There was no relationship between neurological AEs and PAA levels in UCD or HE patients, but transient AEs including headache and nausea that correlated with PAA levels were observed in healthy adults. Irrespective of population, a curvilinear relationship was observed between PAA levels and the plasma PAA:PAGN ratio, and a ratio>2.5 (both in μg/mL) in a random blood draw identified patients at risk for PAA levels>500 μg/ml. CONCLUSIONS The presence of a relationship between PAA levels and reversible AEs in healthy adults but not in UCD or HE patients may reflect intrinsic differences among the populations and/or metabolic adaptation with continued dosing. The plasma PAA:PAGN ratio is a functional measure of the rate of PAA metabolism and represents a useful dosing biomarker.
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Affiliation(s)
- M Mokhtarani
- Hyperion Therapeutics, 601 Gateway Blvd., Suite 200, South San Francisco, CA 94080, USA.
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7
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Abstract
Argininosuccinic aciduria (ASA) is a urea cycle disorder with a complex phenotype. In spite of a lower risk for recurrent hyperammonemic episodes as compared to the proximal disorders of ureagenesis, subjects with ASA are at risk for long-term complications including, poor neurocognitive outcome, hepatic disease and systemic hypertension. These complications can occur in spite of current standard therapy that includes dietary modifications and arginine supplementation suggesting that the presently available therapy is suboptimal. In this article, we discuss the natural history of ASA and the recent mechanistic insights from animal studies that have shown the requirement of argininosuccinate lyase, the enzyme deficient in ASA, for systemic nitric oxide production. These findings may have therapeutic implications and may help optimize therapy in ASA.
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Affiliation(s)
- Sandesh CS Nagamani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Howard Hughes Medical Institute, Houston, USA
- Corresponding author: Brendan Lee, M.D., Ph.D., Investigator, Howard Hughes Medical Institute, Professor, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030., Phone: 713-798-5443, Fax: 713-798-5168,
| | - Ayelet Erez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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