Evaluation of FDA Labeling Changes Related to PREA Safety-Waivers

PURPOSE

The Pediatric Research Equity Act (PREA) gives the US Food and Drug Administration (FDA) authority to require pediatric studies for drug and biologics products under certain circumstances and to waive this requirement in some, or all, pediatric ages. When studies are waived for safety, PREA stipulates the safety issue must be described in labeling. This study assessed the rate of including waiver-related safety information in labeling.

METHODS

FDA databases were reviewed to determine the number of safety-related pediatric study waivers and issued from December 2003 through August 2020, and corresponding labeling to establish when relevant safety information was included. Descriptive comparisons were conducted across Cohort 1: December 2003-2007, Cohort 2: 2008-2011, Cohort 3: 2012-2015, and Cohort 4: 2016-August 2020.

RESULTS

One hundred sixteen safety waivers were issued [Cohort 1 (n = 1); Cohort 2 (n = 38), Cohort 3 (n = 37), and Cohort 4 (n = 40)] for 84 unique drugs or biologics. Most (106 of 116; 91%) waiver-related safety issues were described in labeling [Cohort 1 (1 of 1), Cohort 2 (33 of 38), Cohort 3 (33 of 37), and Cohort 4 (39 of 40)]. Safety waivers were most common in patients ≤ 17 years (n = 40) and least common in patients ≤ 6 months (n = 15). Products for infections (n = 32) were the most common group receiving safety waivers; 17 for non-antiviral anti-infective products including treatments for dermatologic infestations/infections, and 15 for antiviral products.

CONCLUSION

The data confirm that FDA consistently describes waiver-related safety information in drug/biologic product labeling since the inception of PREA in December of 2003.

Development of a Prospective Real-World Data Clinical Registry of Children and Adolescents With Migraine

OBJECTIVE

To develop a multicenter, multistakeholder, prospective clinical registry of children and adolescents with migraine to support the collection of real-world data of sufficient quality to support regulatory submissions and provide site-based infrastructure support for future clinical trials.

BACKGROUND

As new migraine treatments come to market, pediatric efficacy and safety trials of these agents are needed. A clinical registry is an ideal regulatory strategy to provide both real-world data and site infrastructure to execute these trials.

DESIGN

Multicenter, multistakeholder, prospective real-world data clinical registry of children and adolescents, 4-17 years of age, diagnosed with migraine with or without aura. Participants will be followed for up to 12 months at 3-month intervals, with interval recording of clinical data at study sites and self-reported data via mobile health application, as well as biobanking. We developed electronic case report forms that incorporated routinely collected clinical data with National Institute of Neurological Disorders and Stroke Headache Common Data Elements (Version 2.0). All data are captured in a 21 CFR Part 11 - compliant electronic data capture system - augmented by a real-time, web-based, and customizable data visualization platform. We engaged vendors to provide ancillary biobanking, patient data entry, and data visualization services.

RESULTS

We used an iterative and highly collaborative multistakeholder approach to design and implement a streamlined registry protocol with input from all participating US sites. At each design and implementation step, we received input from therapeutic area experts, the US Food and Drug Administration (FDA), the National Institutes of Health, patient and parent advocates, health technology partners, drug developers, and site-based clinical investigators. The registry is governed by a multistakeholder steering committee with representation from sites, industry partners, patient advocates, and a member from the FDA (non-voting with respect to steering committee matters). The multistakeholder and site-driven approach to registry design and execution was highly efficient and resulted in the first patient enrolled within 6 months of concept development.

CONCLUSIONS

By ensuring regulatory compliant implementation of the registry, we created both a source of real-world data and a multisite platform for the conduct of future clinical trials that can be submitted to regulatory authorities to support inclusion of pediatric data in approved drug labeling. A highly collaborative approach with broad stakeholder engagement at all stages of the registry development was a key to our operational success.

Consensus interpretation of the p.Met34Thr and p.Val37Ile variants in GJB2 by the ClinGen Hearing Loss Expert Panel

PURPOSE

Pathogenic variants in GJB2 are the most common cause of autosomal recessive sensorineural hearing loss. The classification of c.101T>C/p.Met34Thr and c.109G>A/p.Val37Ile in GJB2 are controversial. Therefore, an expert consensus is required for the interpretation of these two variants.

METHODS

The ClinGen Hearing Loss Expert Panel collected published data and shared unpublished information from contributing laboratories and clinics regarding the two variants. Functional, computational, allelic, and segregation data were also obtained. Case-control statistical analyses were performed.

RESULTS

The panel reviewed the synthesized information, and classified the p.Met34Thr and p.Val37Ile variants utilizing professional variant interpretation guidelines and professional judgment. We found that p.Met34Thr and p.Val37Ile are significantly overrepresented in hearing loss patients, compared with population controls. Individuals homozygous or compound heterozygous for p.Met34Thr or p.Val37Ile typically manifest mild to moderate hearing loss. Several other types of evidence also support pathogenic roles for these two variants.

CONCLUSION

Resolving controversies in variant classification requires coordinated effort among a panel of international multi-institutional experts to share data, standardize classification guidelines, review evidence, and reach a consensus. We concluded that p.Met34Thr and p.Val37Ile variants in GJB2 are pathogenic for autosomal recessive nonsyndromic hearing loss with variable expressivity and incomplete penetrance.

SubILM Injection of AAV for Gene Delivery to the Retina

Adeno-associated virus (AAV) has emerged as the vector of choice for delivering genes to the retina. Indeed, the first gene therapy to receive FDA approval in the United States is an AAV-based treatment for the inherited retinal disease, Leber congenital amaurosis-2. Voretigene neparvovec (Luxturna™) is delivered to patients via subretinal (SR) injection, an invasive surgical procedure that requires detachment of photoreceptors (PRs) from the retinal pigment epithelium (RPE). It has been reported that subretinal administration of vector under the cone-exclusive fovea leads to a loss of central retinal structure and visual acuity in some patients. Due to its technical difficulty and potential risks, alternatives to SR injection have been explored in primates. Intravitreally (Ivt) delivered AAV transduces inner retina and foveal cones, but with low efficiency. Novel AAV capsid variants identified via rational design or directed evolution have offered only incremental improvements, and have failed to promote pan-inner retinal transduction or significant outer retinal transduction beyond the fovea. Problems with retinal transduction by Ivt-delivered AAV include dilution in the vitreous, potential antibody-mediated neutralization of capsid in this nonimmune privileged space, and the presence of the inner limiting membrane (ILM), a basement membrane separating the vitreous from the neural retina. We have developed an alternative "subILM" injection method that overcomes all three hurdles. Specifically, vector is placed in a surgically induced, hydrodissected space between the ILM and neural retina. We have shown that subILM injection promotes more efficient retinal transduction by AAV than Ivt injection, and results in uniform and extensive transduction of retinal ganglion cells (RGCs) beneath the subILM bleb. We have also demonstrated transduction of Muller glia, ON bipolar cells, and photoreceptors by subILM injection. Our results confirm that the ILM is a major barrier to transduction by AAV in primate retina and that, when it is circumvented, the efficiency and depth to which AAV2 promotes transduction of multiple retinal cell classes is greatly enhanced. Here we describe in detail methods for vector preparation, vector dilution, and subILM injection as performed in macaque (Macaca sp.).

Genetic landscape and novel disease mechanisms from a large LGMD cohort of 4656 patients

Objective

Limb‐girdle muscular dystrophies (LGMDs), one of the most heterogeneous neuromuscular disorders (NMDs), involves predominantly proximal‐muscle weakness with >30 genes associated with different subtypes. The clinical‐genetic overlap among subtypes and with other NMDs complicate disease‐subtype identification lengthening diagnostic process, increases overall costs hindering treatment/clinical‐trial recruitment. Currently seven LGMD clinical trials are active but still no gene‐therapy‐related treatment is available. Till‐date no nation‐wide large‐scale LGMD sequencing program was performed. Our objectives were to understand LGMD genetic basis, different subtypes’ relative prevalence across US and investigate underlying disease mechanisms.

Methods

A total of 4656 patients with clinically suspected‐LGMD across US were recruited to conduct next‐generation sequencing (NGS)‐based gene‐panel testing during June‐2015 to June‐2017 in CLIA‐CAP‐certified Emory‐Genetics‐Laboratory. Thirty‐five LGMD‐subtypes‐associated or LGMD‐like other NMD‐associated genes were investigated. Main outcomes were diagnostic yield, gene‐variant spectrum, and LGMD subtypes’ prevalence in a large US LGMD‐suspected population.

Results

Molecular diagnosis was established in 27% (1259 cases; 95% CI, 26–29%) of the patients with major contributing genes to LGMD phenotypes being: CAPN3(17%), DYSF(16%), FKRP(9%) and ANO5(7%). We observed an increased prevalence of genetically confirmed late‐onset Pompe disease, DNAJB6‐associated LGMD subtype1E and CAPN3‐associated autosomal‐dominant LGMDs. Interestingly, we identified a high prevalence of patients with pathogenic variants in more than one LGMD gene suggesting possible synergistic heterozygosity/digenic/multigenic contribution to disease presentation/progression that needs consideration as a part of diagnostic modality.

Interpretation

Overall, this study has improved our understanding of the relative prevalence of different LGMD subtypes, their respective genetic etiology, and the changing paradigm of their inheritance modes and novel mechanisms that will allow for improved timely treatment, management, and enrolment of molecularly diagnosed individuals in clinical trials.

SLC6A1 variants identified in epilepsy patients reduce γ-aminobutyric acid transport

Previous reports have identified SLC6A1 variants in patients with generalized epilepsies, such as myoclonic-atonic epilepsy and childhood absence epilepsy. However, to date, none of the identified SLC6A1 variants has been functionally tested for an effect on GAT-1 transporter activity. The purpose of this study was to determine the incidence of SLC6A1 variants in 460 unselected epilepsy patients and to evaluate the impact of the identified variants on γ-aminobutyric acid (GABA)transport. Targeted resequencing was used to screen 460 unselected epilepsy patients for variants in SLC6A1. Five missense variants, one in-frame deletion, one nonsense variant, and one intronic splice-site variant were identified, representing a 1.7% diagnostic yield. Using a [³ H]-GABA transport assay, the seven identified exonic variants were found to reduce GABA transport activity. A minigene splicing assay revealed that the splice-site variant disrupted canonical splicing of exon 9 in the mRNA transcript, leading to premature protein truncation. These findings demonstrate that SLC6A1 is an important contributor to childhood epilepsy and that reduced GAT-1 function is a common consequence of epilepsy-causing SLC6A1 variants.

De novo variants in GABRA2 and GABRA5 alter receptor function and contribute to early-onset epilepsy

GABAA receptors are ligand-gated anion channels that are important regulators of neuronal inhibition. Mutations in several genes encoding receptor subunits have been identified in patients with various types of epilepsy, ranging from mild febrile seizures to severe epileptic encephalopathy. Using whole-genome sequencing, we identified a novel de novo missense variant in GABRA5 (c.880G > C, p.V294L) in a patient with severe early-onset epilepsy and developmental delay. Targeted resequencing of 279 additional epilepsy patients identified 19 rare variants from nine GABAA receptor genes, including a novel de novo missense variant in GABRA2 (c.875C > A, p.T292K) and a recurrent missense variant in GABRB3 (c.902C > T, p.P301L). Patients with the GABRA2 and GABRB3 variants also presented with severe epilepsy and developmental delay. We evaluated the effects of the GABRA5, GABRA2 and GABRB3 missense variants on receptor function using whole-cell patch-clamp recordings from human embryonic kidney 293T cells expressing appropriate α, β and γ subunits. The GABRA5 p.V294L variant produced receptors that were 10-times more sensitive to GABA but had reduced maximal GABA-evoked current due to increased receptor desensitization. The GABRA2 p.T292K variant reduced channel expression and produced mutant channels that were tonically open, even in the absence of GABA. Receptors containing the GABRB3 p.P301L variant were less sensitive to GABA and produced less GABA-evoked current. These results provide the first functional evidence that de novo variants in the GABRA5 and GABRA2 genes contribute to early-onset epilepsy and developmental delay, and demonstrate that epilepsy can result from reduced neuronal inhibition via a wide range of alterations in GABAA receptor function.

Is exon 8 the most critical or the only dispensable exon of the VCAN gene? Insights into VCAN variants and clinical spectrum of Wagner syndrome

Wagner syndrome and erosive vitreoretinopathy together constitute the phenotypic continuum of an autosomal dominant vitreoretinopathy, with clinical findings typically isolated to the eye. The disease is caused by pathogenic variants in the VCAN gene and all such variants reported to date are those that plausibly result in haploinsufficiency of exon 8 containing vcan transcripts. Here, we report the molecular findings and long-term follow-up of a 16-year-old female with a history of retinal detachments and pigmentary retinal changes. Next-generation sequencing and microarray analysis of 141 genes established a diagnosis of Wagner syndrome in this individual, by detection of an 11.7 kilobase (kb) deletion encompassing exon 8 of VCAN. In light of the emerging functions and roles of versican protein in human disease, we discuss how variants within exon 8 of the VCAN gene can be compared to those in exon 2 of the COL2A1 gene that cause atypical Stickler syndrome and propose that variants in other regions of the gene can be expected to present with a more systemic disease. The distinctive facial features and atypical gastrointestinal symptoms observed in this long-term follow-up study support the possibility that individuals with VCAN-related vitreoretinopathy may have extra-ocular clinical features.

Urine oligosaccharide screening by MALDI-TOF for the identification of NGLY1 deficiency

N-glycanase deficiency (NGLY1 deficiency, NGLY1-CDDG), the first autosomal recessive congenital disorder of N-linked deglycosylation (CDDG), is caused by pathogenic variants in NGLY1. The majority of affected individuals have been identified using exome or genome sequencing. To date, no reliable, clinically available biomarkers have been identified. Urine oligosaccharide analysis was included as part of a routine evaluation for possible biomarkers in patients with confirmed NGLY1-CDDG. During the qualitative review of oligosaccharide profiles by an experienced laboratory director an abnormal analyte with a proposed structure of Neu5Ac1Hex1GlcNAc1-Asn was identified in NGLY1-CDDG patient urine samples. The same species has been observed in profiles from individuals affected with aspartylglucosaminuria, although the complete spectra are not identical. Additional studies using tandem mass spectrometry confirmed the analyte's structure. In addition to the known NGLY1-CDDG patients identified by this analysis, a single case was identified in a population referred for clinical testing who subsequently had a diagnosis of NGLY1-CDDG confirmed by molecular testing. Urine oligosaccharide screening by MALDI-TOF MS can identify individuals with NGLY1-CDDG. In addition, this potential biomarker might also be used to monitor the effectiveness of therapeutic options as they become available.

Moonlighting newborn screening markers: the incidental discovery of a second-tier test for Pompe disease

PURPOSE

To describe a novel biochemical marker in dried blood spots suitable to improve the specificity of newborn screening for Pompe disease.

METHODS

The new marker is a ratio calculated between the creatine/creatinine (Cre/Crn) ratio as the numerator and the activity of acid α-glucosidase (GAA) as the denominator. Using Collaborative Laboratory Integrated Reports (CLIR), the new marker was incorporated in a dual scatter plot that can achieve almost complete segregation between Pompe disease and false-positive cases.

RESULTS

The (Cre/Crn)/GAA ratio was measured in residual dried blood spots of five Pompe cases and was found to be elevated (range 4.41-13.26; 99%ile of neonatal controls: 1.10). Verification was by analysis of 39 blinded specimens that included 10 controls, 24 samples with a definitive classification (16 Pompe, 8 false positives), and 5 with genotypes of uncertain significance. The CLIR tool showed 100% concordance of classification for the 24 known cases. Of the remaining five cases, three p.V222M homozygotes, a benign variant, were classified by CLIR as false positives; two with genotypes of unknown significance, one likely informative, were categorized as Pompe disease.

CONCLUSION

The CLIR tool inclusive of the new ratio could have prevented at least 12 of 13 (92%) false-positive outcomes.

Early-Life Epilepsies and the Emerging Role of Genetic Testing

IMPORTANCE

Early-life epilepsies are often a consequence of numerous neurodevelopmental disorders, most of which are proving to have genetic origins. The role of genetic testing in the initial evaluation of these epilepsies is not established.

OBJECTIVE

To provide a contemporary account of the patterns of use and diagnostic yield of genetic testing for early-life epilepsies.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective cohort, children with newly diagnosed epilepsy with an onset at less than 3 years of age were recruited from March 1, 2012, to April 30, 2015, from 17 US pediatric hospitals and followed up for 1 year. Of 795 families approached, 775 agreed to participate. Clinical diagnosis of the etiology of epilepsy were characterized based on information available before genetic testing was performed. Added contributions of cytogenetic and gene sequencing investigations were determined.

EXPOSURES

Genetic diagnostic testing.

MAIN OUTCOMES AND MEASURES

Laboratory-confirmed pathogenic variant.

RESULTS

Of the 775 patients in the study (367 girls and 408 boys; median age of onset, 7.5 months [interquartile range, 4.2-16.5 months]), 95 (12.3%) had acquired brain injuries. Of the remaining 680 patients, 327 (48.1%) underwent various forms of genetic testing, which identified pathogenic variants in 132 of 327 children (40.4%; 95% CI, 37%-44%): 26 of 59 (44.1%) with karyotyping, 32 of 188 (17.0%) with microarrays, 31 of 114 (27.2%) with epilepsy panels, 11 of 33 (33.3%) with whole exomes, 4 of 20 (20.0%) with mitochondrial panels, and 28 of 94 (29.8%) with other tests. Forty-four variants were identified before initial epilepsy presentation. Apart from dysmorphic syndromes, pathogenic yields were highest for children with tuberous sclerosis complex (9 of 11 [81.8%]), metabolic diseases (11 of 14 [78.6%]), and brain malformations (20 of 61 [32.8%]). A total of 180 of 446 children (40.4%), whose etiology would have remained unknown without genetic testing, underwent some testing. Pathogenic variants were identified in 48 of 180 children (26.7%; 95% CI, 18%-34%). Diagnostic yields were greater than 15% regardless of delay, spasms, and young age. Yields were greater for epilepsy panels (28 of 96 [29.2%]; P < .001) and whole exomes (5 of 18 [27.8%]; P = .02) than for chromosomal microarray (8 of 101 [7.9%]).

CONCLUSIONS AND RELEVANCE

Genetic investigations, particularly broad sequencing methods, have high diagnostic yields in newly diagnosed early-life epilepsies regardless of key clinical features. Thorough genetic investigation emphasizing sequencing tests should be incorporated into the initial evaluation of newly presenting early-life epilepsies and not just reserved for those with severe presentations and poor outcomes.

Highly Efficient Delivery of Adeno-Associated Viral Vectors to the Primate Retina

Adeno-associated virus (AAV) has emerged as the preferred vector for targeting gene expression to the retina. Subretinally injected AAV can efficiently transduce retinal pigment epithelium and photoreceptors in primate retina. Inner and middle primate retina can be transduced by intravitreally delivered AAV, but with low efficiency. This is due to dilution of vector, potential neutralization of capsid because it is not confined to the immune-privileged retinal compartment, and the presence of the inner limiting membrane (ILM), a barrier separating the vitreous from the neural retina. We here describe a novel "subILM" injection method that addresses all three issues. Specifically, vector is placed in a surgically induced, hydrodissected space between the ILM and neural retina. In an initial experiment, we injected viscoelastic (Healon(®)), a substance we confirmed was biocompatible with AAV, to create a subILM bleb and subsequently injected AAV2-GFP into the bleb after irrigation with basic salt solution. For later experiments, we used a Healon-AAV mixture to place single, subILM injections. In all cases, subILM delivery of AAV was well tolerated-no inflammation or gross structural changes were observed by ophthalmological examination or optical coherence tomography. In-life fluorescence imaging revealed profound transgene expression within the area of the subILM injection bleb that persisted for the study duration. Uniform and extensive transduction of retinal ganglion cells (RGCs) was achieved in the areas beneath the subILM bleb. Transduction of Müller glia, ON bipolar cells, and photoreceptors was also observed. Robust central labeling from green fluorescent protein-expressing RGCs confirmed their continued survival, and was observed in the lateral geniculate nucleus, the superior colliculus, and the pretectum. Our results confirm that the ILM is a major barrier to transduction by AAV in primate retina and that, when it is circumvented, the efficiency and depth to which AAV2 promotes transduction of multiple retinal cell classes are greatly enhanced.

Optimization of Retinal Gene Therapy for X-Linked Retinitis Pigmentosa Due to RPGR Mutations

X-linked retinitis pigmentosa (XLRP) caused by mutations in the RPGR gene is an early onset and severe cause of blindness. Successful proof-of-concept studies in a canine model have recently shown that development of a corrective gene therapy for RPGR-XLRP may now be an attainable goal. In preparation for a future clinical trial, we have here optimized the therapeutic AAV vector construct by showing that GRK1 (rather than IRBP) is a more efficient promoter for targeting gene expression to both rods and cones in non-human primates. Two transgenes were used in RPGR mutant (XLPRA2) dogs under the control of the GRK1 promoter. First was the previously developed stabilized human RPGR (hRPGRstb). Second was a new full-length stabilized and codon-optimized human RPGR (hRPGRco). Long-term (>2 years) studies with an AAV2/5 vector carrying hRPGRstb under control of the GRK1 promoter showed rescue of rods and cones from degeneration and retention of vision. Shorter term (3 months) studies demonstrated comparable preservation of photoreceptors in canine eyes treated with an AAV2/5 vector carrying either transgene under the control of the GRK1 promoter. These results provide the critical molecular components (GRK1 promoter, hRPGRco transgene) to now construct a therapeutic viral vector optimized for RPGR-XLRP patients.

Novel Methodology for Creating Macaque Retinas with Sortable Photoreceptors and Ganglion Cells

Purpose: The ability to generate macaque retinas with sortable cell populations would be of great benefit to both basic and translational studies of the primate retina. The purpose of our study was therefore to develop methods to achieve this goal by selectively labeling, in life, photoreceptors (PRs) and retinal ganglion cells (RGCs) with separate fluorescent markers. Methods: Labeling of macaque (Macaca fascicularis) PRs and RGCs was accomplished by subretinal delivery of AAV5-hGRK1-GFP, and retrograde transport of micro-ruby™ from the lateral geniculate nucleus, respectively. Retinas were anatomically separated into different regions. Dissociation conditions were optimized, and cells from each region underwent fluorescent activated cell sorting (FACS). Expression of retinal cell type- specific genes was assessed by quantitative real-time PCR to characterize isolated cell populations. Results: We show that macaque PRs and RGCs can be simultaneously labeled in-life and enriched populations isolated by FACS. Recovery from different retinal regions indicated efficient isolation/enrichment for PRs and RGCs, with the macula being particularly amendable to this technique. Conclusions: The methods and materials presented here allow for the identification of novel reagents designed to target RGCs and/or photoreceptors in a species that is phylogenetically and anatomically similar to human. These techniques will enable screening of intravitreally-delivered AAV capsid libraries for variants with increased tropism for PRs and/or RGCs and the evaluation of vector tropism and/or cellular promoter activity of gene therapy vectors in a clinically relevant species.

Factor H uptake regulates intracellular C3 activation during apoptosis and decreases the inflammatory potential of nucleosomes

Factor H (FH) binds apoptotic cells to limit the inflammatory potential of complement. Here we report that FH is actively internalized by apoptotic cells to enhance cathepsin L-mediated cleavage of endogenously expressed C3, which results in increased surface opsonization with iC3b. In addition, internalized FH forms complexes with nucleosomes, facilitates their phagocytosis by monocytes and induces an anti-inflammatory biased cytokine profile. A similar cytokine response was noted for apoptotic cells coated with FH, confirming that FH diminishes the immunogenic and inflammatory potential of autoantigens. These findings were supported by in vivo observations from CFH(-/-) MRL-lpr mice, which exhibited higher levels of circulating nucleosomes and necrotic cells than their CFH(+/+) littermates. This unconventional function of FH broadens the established view of apoptotic cell clearance and appears particularly important considering the strong associations with genetic FH alterations and diseases such as systemic lupus erythematosus and age-related macular degeneration.

Csf2 and Ptgs2 Epigenetic Dysregulation in Diabetes-prone Bicongenic B6.NODC11bxC1tb Mice

In Type 1 diabetic (T1D) human monocytes, STAT5 aberrantly binds to epigenetic regulatory sites of two proinflammatory genes, CSF2 (encoding granulocyte-macrophage colony-stimulating factor) and PTGS2 (encoding prostaglandin synthase 2/cyclooxygenase 2). Bicongenic B6.NOD C11bxC1tb mice re-create this phenotype of T1D monocytes with only two nonobese diabetic (NOD) Idd subloci (130.8 Mb-149.7 Mb, of Idd5 on Chr 1 and 32.08-53.85 Mb of Idd4.3 on Chr11) on C57BL/6 genetic background. These two Idd loci interact through STAT5 binding at upstream regulatory regions affecting Csf2 (Chr 11) and Ptgs2 (Chr 1) expression. B6.NODC11bxC1tb mice exhibited hyperglycemia and immune destruction of pancreatic islets between 8 and 30 weeks of age, with 12%-22% penetrance. Thus, B6.NODC11bxC1tb mice embody NOD epigenetic dysregulation of gene expression in myeloid cells, and this defect appears to be sufficient to impart genetic susceptibility to diabetes in an otherwise genetically nonautoimmune mouse.

Pediatric patient-reported outcome instruments for research to support medical product labeling: report of the ISPOR PRO good research practices for the assessment of children and adolescents task force

BACKGROUND

Patient-reported outcome (PRO) instruments for children and adolescents are often included in clinical trials with the intention of collecting data to support claims in a medical product label.

OBJECTIVE

The purpose of the current task force report is to recommend good practices for pediatric PRO research that is conducted to inform regulatory decision making and support claims made in medical product labeling. The recommendations are based on the consensus of an interdisciplinary group of researchers who were assembled for a task force associated with the International Society for Pharmacoeconomics and Outcomes Research (ISPOR). In those areas in which supporting evidence is limited or in which general principles may not apply to every situation, this task force report identifies factors to consider when making decisions about the design and use of pediatric PRO instruments, while highlighting issues that require further research.

GOOD RESEARCH PRACTICES

Five good research practices are discussed: 1) Consider developmental differences and determine age-based criteria for PRO administration: Four age groups are discussed on the basis of previous research (<5 years old, 5-7 years, 8-11 years, and 12-18 years). These age groups are recommended as a starting point when making decisions, but they will not fit all PRO instruments or the developmental stage of every child. Specific age ranges should be determined individually for each population and PRO instrument. 2) Establish content validity of pediatric PRO instruments: This section discusses the advantages of using children as content experts, as well as strategies for concept elicitation and cognitive interviews with children. 3) Determine whether an informant-reported outcome instrument is necessary: The distinction between two types of informant-reported measures (proxy vs. observational) is discussed, and recommendations are provided. 4) Ensure that the instrument is designed and formatted appropriately for the target age group. Factors to consider include health-related vocabulary, reading level, response scales, recall period, length of instrument, pictorial representations, formatting details, administration approaches, and electronic data collection (ePRO). 5) Consider cross-cultural issues.

CONCLUSIONS

Additional research is needed to provide methodological guidance for future studies, especially for studies involving young children and parents' observational reports. As PRO data are increasingly used to support pediatric labeling claims, there will be more information regarding the standards by which these instruments will be judged. The use of PRO instruments in clinical trials and regulatory submissions will help ensure that children's experience of disease and treatment are accurately represented and considered in regulatory decisions.

The human rhodopsin kinase promoter in an AAV5 vector confers rod- and cone-specific expression in the primate retina

Adeno-associated virus (AAV) has proven an effective gene delivery vehicle for the treatment of retinal disease. Ongoing clinical trials using a serotype 2 AAV vector to express RPE65 in the retinal pigment epithelium have proven safe and effective. While many proof-of-concept studies in animal models of retinal disease have suggested that gene transfer to the neural retina will also be effective, a photoreceptor-targeting AAV vector has yet to be used in the clinic, principally because a vector that efficiently but exclusively targets all primate photoreceptors has yet to be demonstrated. Here, we evaluate a serotype 5 AAV vector containing the human rhodopsin kinase (hGRK1) promoter for its ability to target transgene expression to rod and cone photoreceptors when delivered subretinally in a nonhuman primate (NHP). In vivo fluorescent fundus imaging confirmed that AAV5-hGRK1-mediated green fluorescent protein (GFP) expression was restricted to the injection blebs of treated eyes. Optical coherence tomography (OCT) revealed a lack of gross pathology after injection. Neutralizing antibodies against AAV5 were undetectable in post-injection serum samples from subjects receiving uncomplicated subretinal injections (i.e., no hemorrhage). Immunohistochemistry of retinal sections confirmed hGRK1 was active in, and specific for, both rods and cones of NHP retina. Biodistribution studies revealed minimal spread of vector genomes to peripheral tissues. These results suggest that AAV5-hGRK1 is a safe and effective AAV serotype/promoter combination for targeting therapeutic transgene expression protein to rods and cones in a clinical setting.

Gene therapy rescues cone function in congenital achromatopsia

The successful restoration of visual function with recombinant adeno-associated virus (rAAV)-mediated gene replacement therapy in animals and humans with an inherited disease of the retinal pigment epithelium has ushered in a new era of retinal therapeutics. For many retinal disorders, however, targeting of therapeutic vectors to mutant rods and/or cones will be required. In this study, the primary cone photoreceptor disorder achromatopsia served as the ideal translational model to develop gene therapy directed to cone photoreceptors. We demonstrate that rAAV-mediated gene replacement therapy with different forms of the human red cone opsin promoter led to the restoration of cone function and day vision in two canine models of CNGB3 achromatopsia, a neuronal channelopathy that is the most common form of achromatopsia in man. The robustness and stability of the observed treatment effect was mutation independent, but promoter and age dependent. Subretinal administration of rAAV5-hCNGB3 with a long version of the red cone opsin promoter in younger animals led to a stable therapeutic effect for at least 33 months. Our results hold promise for future clinical trials of cone-directed gene therapy in achromatopsia and other cone-specific disorders.

C3aR inhibition reduces neurodegeneration in experimental lupus

Complement activation is an important aspect of systemic lupus erythematosus. In this study we investigated the role of C3a/C3a receptor (R) signaling in brains of the lupus model, MRL/lpr mice, by treating the mice with C3aR antagonist (a) from 13 to 19 weeks of age. C3aR mRNA (0.2 +/- 0.027 versus 0.56 +/- 0.19) and protein (0.16 +/- 0.09 versus 0.63 +/- 0.19) expression was increased in MRL/lpr brains compared with MRL+/+ controls. Apoptosis, a key feature in lupus brain, was significantly reduced by C3aRa treatment, as assessed by DNA laddering, TUNEL staining and caspase3 activity (48% of MRL/lpr mice). mRNA expression of proinflammatory molecules that cause apoptosis, TNFalpha (0.33 +/- 0.07 versus 0.15 +/- 0.1), MIP2 (3.8 +/- 1.3 versus 1.7 +/- 0.6), and INFgamma (4.8 +/- 1.0 versus 2.07 +/- 1.28) are reduced in MRL/lpr brains with C3aRa treatment. In line with these results, Western blotting demonstrates the significant increase in phosphorylation of survival molecules Akt and Erk, decrease in PTEN and reduced iNOS expression. INFgamma receptor (R) and AMPA-GluR1 co-localized, and concomitant with reduced INFgammaR expression, AMPAGluR1 expression was also decreased by C3aR antagonist. All of these variables that modulate neuronal excitability and regulate synaptic plasticity are C3aR dependent in the MRL/lpr brains and suggest a potential therapeutic role for C3aR inhibition in CNS lupus.

Immune depletion with cellular mobilization imparts immunoregulation and reverses autoimmune diabetes in nonobese diabetic mice

OBJECTIVE

The autoimmune destruction of beta-cells in type 1 diabetes results in a loss of insulin production and glucose homeostasis. As such, an immense interest exists for the development of therapies capable of attenuating this destructive process through restoration of proper immune recognition. Therefore, we investigated the ability of the immune-depleting agent antithymocyte globulin (ATG), as well as the mobilization agent granulocyte colony-stimulating factor (GCSF), to reverse overt hyperglycemia in the nonobese diabetic (NOD) mouse model of type 1 diabetes.

RESEARCH DESIGN AND METHODS

Effects of each therapy were tested in pre-diabetic and diabetic female NOD mice using measurements of glycemia, regulatory T-cell (CD4+CD25+Foxp3+) frequency, insulitis, and/or beta-cell area.

RESULTS

Here, we show that combination therapy of murine ATG and GCSF was remarkably effective at reversing new-onset diabetes in NOD mice and more efficacious than either agent alone. This combination also afforded durable reversal from disease (>180 days postonset) in animals having pronounced hyperglycemia (i.e., up to 500 mg/dl). Additionally, glucose control improved over time in mice subject to remission from type 1 diabetes. Mechanistically, this combination therapy resulted in both immunological (increases in CD4-to-CD8 ratios and splenic regulatory T-cell frequencies) and physiological (increase in the pancreatic beta-cell area, attenuation of pancreatic inflammation) benefits.

CONCLUSIONS

In addition to lending further credence to the notion that combination therapies can enhance efficacy in addressing autoimmune disease, these studies also support the concept for utilizing agents designed for other clinical applications as a means to expedite efforts involving therapeutic translation.

Neuroimaging-use trends in nonacute pediatric headache before and after clinical practice parameters

OBJECTIVES

The objective of this study was to determine trends in diagnostic neuroimaging-use rates in nonacute pediatric headache before and after publication of clinical practice guidelines.

METHODS

Retrospective, cross-sectional analysis was conducted of neuroimaging rates for 725 children and adolescents who were aged 3 to 18 years with nonacute headache and normal neurologic examination and were evaluated in a single pediatric neurology clinic during study years 1992, 1996, 2000, and 2004. Following recommendations of current practice parameters, patients with conditions that justify consideration for neuroimaging (eg, progressive headache, abnormal neurologic examination) were excluded from this analysis. We recorded the origin of any neuroimaging request at the time of the clinic visit and any abnormal neuroimaging findings that led to major clinical consequences.

RESULTS

Overall, the mean rate of neuroimaging for patients with nonacute headache was 45%. Use rates remained steady during the 13-year study period (range: 41%-47%). The majority of neuroimaging studies were ordered originally by primary care providers. The proportion of neuroimaging studies that were ordered by primary care providers increased significantly from 1992 to 2004.

CONCLUSIONS

In the evaluation of patients who had nonacute pediatric headache and were referred to a child neurology clinic, neuroimaging-use rates remained stable during the past decade. An increasing proportion of neuroimaging studies are ordered by primary care providers. The influence of evidence-based medicine on medical decision-making may be partly responsible for curbing increases in neuroimaging overuse. The perceived value of neuroimaging by physicians and consumers deserves ongoing study.

Prospects for retinal cone-targeted gene therapy

Gene therapy strategies that target therapeutic genes to retinal cones are a worthy goal both because cone photoreceptor diseases are severely vision limiting and because many retinal diseases that do not affect cones directly eventually lead to cone loss, the reason for eventual blindness. Human achromatopsia is a genetic disease of cones that renders them nonfunctional but otherwise intact. Thus, animal models of achromatopsia were used in conjunction with adeno-associated virus (AAV) vectors whose serotype efficiently transduces cones and with a promoter that limits transgene expression to cones. In the Gnat2(cpfl3) mouse model of one genetic form of human achromatopsia, we were able to demonstrate recovery of normal cone function and visual acuity after a single subretinal treatment of vector that supplied wild-type Gnat2 protein to cones. This validates the overall strategy of targeting cones using recombinant viral vectors and justifies a more complete examination of animal models of cone disease as a prelude to considering a clinical gene therapy trial.

Optimising piperacillin/tazobactam dosing in paediatrics

Piperacillin/tazobactam, an intravenous antibacterial combination product, has recently been approved for paediatric (age 2 months to 17 years) use in the USA. The purpose of this analysis is to describe the basis for the dosing recommendations in this age group. Pharmacokinetic (PK) parameters and demographic covariates from 53 children enrolled in two paediatric studies were used in the analysis. Individual drug clearance (CL) values calculated by non-compartmental methods were available. The influence of demographic covariates on CL was investigated by non-linear regression. The analysis identified CL to be dependent on body weight. CL was also found to be influenced by age in paediatric patients<or=2 years, which is consistent with the expectation based on maturation of renal function. The population PK analysis and simulations, utilising comparable adult exposures as a basis to explore optimal dosing, resulted in the following dosing recommendations: for paediatric patients>or=9 months, a dose of 100/12.5 mg/kg every 8h showed exposures similar to adults; for paediatric patients aged 2-9 months, the dose of 100/12.5 mg/kg should be reduced by a factor of 0.8 (i.e. 80/10 mg/kg), likely due to immature renal function. Based upon this analysis, dosing recommendations for paediatric patients down to 2 months of age were incorporated in the labelling. No data were available to allow additional recommendations for paediatric patients<2 months of age to be made.

Restoration of cone vision in a mouse model of achromatopsia

Loss of cone function in the central retina is a pivotal event in the development of severe vision impairment for many prevalent blinding diseases. Complete achromatopsia is a genetic defect resulting in cone vision loss in 1 in 30,000 individuals. Using adeno-associated virus (AAV) gene therapy, we show that it is possible to target cones and rescue both the cone-mediated electroretinogram response and visual acuity in the Gnat2 ( cpfl3 ) mouse model of achromatopsia.

Altered vitamin D metabolism in type II diabetic mouse glomeruli may provide protection from diabetic nephropathy

The db/db mouse develops features of type II diabetes mellitus as the result of impaired signaling through its abnormal leptin receptor. In spite of accurate metabolic features of diabetes, renal disease manifestations in these mice are not as severe as in humans suggesting the presence of protective genes. There is a growing body of evidence in humans for the relevance of vitamin D in diabetes. Here we followed a large cohort of db/db mice and their non-diabetic db/+ littermates. Transcriptional profiling revealed significant upregulation of 23 genes involved in Ca2+ homeostasis and vitamin D metabolism in db/db glomeruli relative to db/+ glomeruli. Increased glomerular expression of vitamin D3 1alpha-hydroxylase, vitamin D binding protein, calbindins D9K and D28K, and calcyclin mRNA was confirmed by quantitative reverse transcription-polymerase chain reaction in 20-, 36-, and 52-week-old db/db glomeruli. Although vitamin D3 1alpha-hydroxylase protein was primarily expressed and upregulated in db/db renal tubules, it was also expressed in glomerular podocytes in vivo. Serum 1,25-dihydroxyvitamin D3 and urinary Ca2+ excretion were increased >3-fold in db/db mice compared to db/+ mice. Cultured glomerular podocytes had mRNA for vitamin D3 1alpha-hydroxylase, vitamin D receptor, and calbindin D28K, each of which was increased in high glucose conditions. High glucose also led to enhanced production of fibronectin and collagen IV protein, which was blocked by 1,25-dihydroxyvitamin D3. These results show that vitamin D metabolism is altered in db/db mice leading to metabolic and transcriptional effects. The podocyte is affected by paracrine and potentially autocrine effects of vitamin D, which may explain why db/db mice are resistant to progressive diabetic nephropathy.

Stroke associated with central nervous system vasculitis after West Nile virus infection

We report the association of West Nile virus infection, isolated vasculitis, and stroke in a 9-year-old girl. West Nile virus is of growing epidemiologic importance and should be considered in the differential diagnosis of stroke etiologies, especially during late summer and in patients with a history of exposure in areas where West Nile virus transmission is present.

Anticipating rotavirus vaccines: epidemiology and surveillance of rotavirus in South Africa

Rotavirus infection is associated with acute infantile gastroenteritis in infants and young children globally. In South Africa, rotavirus infection has been shown to be associated with approximately one-quarter of all diarrhoeal admissions to hospital. Rotavirus infection predominantly occurs in infants less than 12 months of age (75%) and has a peak of shedding during the cooler, drier months of the year. A secondary peak during the spring has been observed. Multiple infections with rotavirus and at least one other microbial agent are common. The circulating VP7 serotypes and VP4 genotypes have been determined in various regions of South Africa and show a geographic specific distribution. A decade previously, P[8]G1 or G4 strains predominated, and P[4]G2 strains occurred in an epidemic pattern in one region. More recently, rotavirus strains with P[6] genotype have become common and novel VP7/VP4 genotype combinations are occurring across the country. G9 strains have been reported from Cape Town to Vendaland. The circulating rotavirus types observed in this study add to the knowledge of the natural history of rotavirus infection and provide the groundwork to consider future vaccine strategies.

A protein with characteristics of factor H is present on rodent platelets and functions as the immune adherence receptor

Complement-coated particles interact with specific immune adherence receptors (IAR). In primates, this function is served by complement receptor 1 (CR1) on erythrocytes. In contrast, rodent platelets bear IAR distinct from CR1, the identity of which was studied here. A 150-kDa C3b-binding protein was isolated from rat platelets, which had immunochemical and biochemical identity to plasma factor H. Immunofluorescence microscopy and flow cytometry demonstrated that factor H was present on the surface of rat and mouse platelets, which could be removed by treatment with neuraminidase. Sheep erythrocytes bearing C3b underwent immune adherence with rat and mouse platelets, which was blocked with anti-factor H F(ab')(2) antibodies, but not with antibodies binding to the complement regulator, Crry, on the platelet surface. By reverse transcription-polymerase chain reaction using rat platelet RNA and primers designed from mouse factor H, a 472-base pair product was generated that was identical in sequence to that produced from rat liver RNA. The translated protein product was 85% similar to mouse liver factor H. The 3'-nucleotide sequence from platelets predicted a soluble factor H protein. By Northern analysis, liver and platelets had identically sized factor H mRNA. Thus, rat and mouse platelets have a membrane protein with characteristics of factor H that is linked via sialic acid residues and functions as the IAR. Whether platelet factor H is acquired by passive adsorption from sera and/or is produced by platelets remains to be determined.

Metal-induced hormesis requires cPKC-dependent glucose transport and lowered respiration

Previously, cytotoxicity studies using an 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT)-based in vitro toxicity assay found that low concentrations of mercuric, cadmium and cupric chloride (0.7, 1 and 3 pM, respectively) induced hormesis in McCoy cells after 24 h exposure. An investigation of the biochemical events required for the induction of this phenomenon revealed that hormesis was dependent on two simultaneous but independent events, namely, an 11-15% conventional protein kinase C (cPKC)-dependent increase in glucose uptake and a protein synthesis-dependent 19-23% drop in mitochondrial respiration. The inhibition of either event was sufficient to abolish hormesis for all three metal toxicants. Furthermore, an investigation of the energy status of cells prior to and during hormesis revealed an oscillating level of ATP production found to be in phase with mitochondrial respiration, independent of cPKC-activated glucose transport and found to coincide with a 16-20% drop in AMP-activated protein kinase activity. These findings suggest that hormesis is not a form of energy compensation but is most likely a reductive burst where an increase in glucose uptake together with a simultaneous reduction in oxygen consumption results in a significant increase in reduction equivalents, which may then be utilized by cells to counteract the effects of oxidative stress induced by heavy metal toxicants.

Complement is activated in kidney by endotoxin but does not cause the ensuing acute renal failure

BACKGROUND

Acute renal failure (ARF) in sepsis occurs when the release of multiple inflammatory mediators is induced by bacterial endotoxins. C3 mRNA is markedly up-regulated in mouse kidney after exposure to lipopolysaccharide (LPS). We hypothesized that LPS could induce tubular synthesis and secretion of C3, leading to activation of the complement cascade and direct renal tubular injury.

METHODS

ARF was induced in mice by intravenous injection of LPS and was confirmed by an acute rise in blood urea nitrogen (BUN) and histologically by acute tubular necrosis. Three separate strategies were used to investigate the role of the complement system in this model of ARF: (1) Crry-Ig, a recombinant protein containing the potent murine complement C3 activation inhibitor Crry was injected at the same time as LPS (N = 8). (2) LPS was injected into transgenic mice overexpressing Crry in glomeruli and tubules (N = 8), and (3) LPS was injected into C3-deficient mice (N = 5).

RESULTS

Compared with unmanipulated mice, C3 staining by immunofluorescence (IF) microscopy in mice injected with LPS was greater in renal cortical tubular cells (IF score of 2. 1 +/- 0.1 vs. 1.4 +/- 0.2 in controls, P = 0.013), most prominently at the basolateral surface. LPS injection led to a 16- to 42-fold increase in urinary C3 excretion. Despite reduction or complete elimination of renal C3 with maneuvers suppressing complement activation, BUN values were not statistically different across all groups. In no experiment did BUN values correlate with the extent of C3 staining.

CONCLUSION

Although LPS up-regulates renal C3 synthesis, resulting in basolateral tubular C3 deposition, this is not responsible for LPS-induced ARF in mice.

South African G4P[6] asymptomatic and symptomatic neonatal rotavirus strains differ in their NSP4, VP8*, and VP7 genes

Over the past decade, a G4P[6] strain has been found to be circulating in different neonatal wards in the Pretoria area. This endemic strain was associated with both asymptomatic and symptomatic infection, providing the opportunity to undertake a molecular study of some of the putative "virulence" genes. The genes encoding NSP4, VP8*, and VP7 of two asymptomatic and two Symptomatic strains were sequenced and compared with ST3. Within each of these genes, amino acid substitutions unique to South African strains were recorded. Four conserved amino acid differences between asymptomatic and symptomatic strains at aa 82 (serine to leucine), aa 114 (aspartic acid to glutamic acid), aa 138 (proline to threonine), and aa 169 (leucine to serine) were identified within the NSP4 gene. The hypervariable region of VP8* exhibited 10 specific amino acid differences (at aa 73, 78, 98, 111, 116, 142, 145, 167, 169, and 188) between asymptomatic and symptomatic strains, while three amino acid substitutions within VP7 were noted. These changes to VP7 occurred within the glycosylation site at aa 70 (leucine to serine), at antigenic region A (aa 96, asparagine to threonine), and at aa 318 (aspartic acid to glycine). It may be speculated that these changes are specific to G4P[6] strains. Furthermore, the observed substitutions may also be particular to South African strains. NSP4, VP8*, and VP7 have been associated with virulence and the amino acid substitutions within these genes correlate with both asymptomatic and symptomatic infection observed in neonates.

Hormesis: a stress response in cells exposed to low levels of heavy metals

Cytotoxicity studies using a 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT)-based in vitro toxicity assay revealed that McCoy cells exposed to low concentrations of mercuric (0.7 microM), cadmium (1 microM) and cupric chloride (3 microM) exhibited significant increases in cellular activity. This increased activity, previously termed hormesis, coincided with the production of high levels of the stress proteins, heat shock protein 70 (Hsp 70) and metallothionein, while the high constitutive expression of these proteins in cadmium-resistant mutant (CRM) cells corresponded to constitutive hormetic activity. Hormesis was found to obey uniform kinetics allowing for a mathematical description of this increased activity. These results suggest that hormetic activity is a specific cellular response, and most likely, a stress response to low but harmful levels of toxic agents and may therefore provide a rapid test for the presence of toxicants at concentrations associated with chronic toxicity.

Relevance of commercial diagnostic tests to detection of enteric adenovirus infections in South Africa

The prevalence of enteric adenoviruses detected by an in-house enzyme-linked immunosorbent assay (the RIVM-ELISA) ranged from 13 to 38%, and subgroup F adenoviruses comprised 86%. All subgroup F adenoviruses reacted with both RIVM anti-adenovirus type 40 (Ad40) and anti-adenovirus type 41 (Ad41) monoclonal antibodies but were not detected by Adenoclone Type 40/41 enzyme immunoassay (EIA). The correlation between the Biotrin EIA and RIVM-ELISA results was low (26%). Immunospecific tests suggest that a significant proportion of enteric adenoviruses, possibly comprising previously unidentified or emerging types, are not detected by commercial diagnostic tests in South Africa.