Noncompletion and nonpublication of trials studying rare diseases: A cross-sectional analysis.

BACKGROUND: Rare diseases affect as many as 60 million people in the United States and Europe. However, most rare diseases lack effective therapies and are in critical need of clinical research. Our objective was to determine the frequency of noncompletion and nonpublication of trials studying rare diseases. METHODS AND FINDINGS: We conducted a cross-sectional analysis of randomized clinical trials studying rare diseases as defined by the Genetic and Rare Disease Information Center database that were registered in ClinicalTrials.gov between January 1, 2010, and December 31, 2012, and completed or discontinued by December 31, 2014. Our main outcome measures were the frequency of trial noncompletion and, among completed studies, frequency of trial nonpublication at 2 and 4 years following trial completion. Reasons for discontinuation were extracted from the registry, and trial sponsors were contacted for additional information, as needed. Two independent investigators performed publication searches for each trial in PubMed, EMBASE, and GoogleScholar, allowing for a minimum of 45 months between trial completion and publication. When a publication could not be identified, trial sponsors were contacted to confirm publication status. The impact of funding source on trial noncompletion was assessed with multivariable logistic regression, and the effect on time to publication was examined with Cox proportional hazards regression. Control variables included intervention type, trial phase, masking, enrollment, and study population. We analyzed 659 rare disease trials accounting for 70,305 enrolled patients. Industry was the primary funder for 327 trials (49.6%) and academic institutions for 184 trials (27.9%). There were 79 trials (12.0%) focused on pediatric populations. A total of 199 trials (30.2%) were discontinued. Lack of patient accrual (n = 64, 32.1%) and informative termination (n = 41, 20.6%) were the most common reasons for trial noncompletion. Among completed trials, 306 (66.5%) remained unpublished at 2 years and 142 (31.5%) at 4 years. In multivariable analyses, industry-funded trials were less likely to be discontinued than trials funded by healthcare centers (odds ratio [OR] 2.42; 95% confidence interval [CI] 1.34-4.39, P = 0.003). We found no significant association between funding source and time to publication. A total of 18,148 patients were enrolled in trials that were discontinued or unpublished 4 years after completion. A potential limitation of our study is that certain interventional trials for rare diseases may not have been registered in ClinicalTrials.gov, in particular Phase 0 and Phase I trials, which are not required to be registered. CONCLUSIONS: In this study, over half of clinical trials initiated for rare diseases were either discontinued or not published 4 years after completion, resulting in large numbers of patients with rare diseases exposed to interventions that did not lead to informative findings. Concerted efforts are needed to ensure that participation of patients in rare disease trials advances scientific knowledge and treatments for rare diseases.

Discontinuation and Nonpublication of Randomized Clinical Trials Conducted in Children.

BACKGROUND: Trial discontinuation and nonpublication represent potential waste in research resources and lead to compromises in medical evidence. Pediatric trials may be particularly vulnerable to these outcomes given the challenges encountered in conducting trials in children. We aimed to determine the prevalence of discontinuation and nonpublication of randomized clinical trials (RCTs) conducted in pediatric populations. METHODS: Retrospective, cross-sectional study of pediatric RCTs registered in ClinicalTrials.gov from 2008 to 2010. Data were collected from the registry and associated publications identified (final search on September 1, 2015). RESULTS: Of 559 trials, 104 (19%) were discontinued early, accounting for an estimated 8369 pediatric participants. Difficulty with patient accrual (37%) was the most commonly cited reason for discontinuation. Trials were less likely to be discontinued if they were funded by industry compared with academic institutions (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27-0.77). Of the 455 completed trials, 136 (30%) were not published, representing 69 165 pediatric participants. Forty-two unpublished trials posted results on ClinicalTrials.gov. Trials funded by industry were more than twice as likely to result in nonpublication at 24 and 36 months (OR 2.21, 95% CI 1.35-3.64; OR 3.12, 95% CI 1.6-6.08, respectively) and had a longer mean time to publication compared with trials sponsored by academia (33 vs 24 months, P < .001). CONCLUSIONS: In this sample of pediatric RCTs, discontinuation and nonpublication were common, with thousands of children exposed to interventions that did not lead to informative or published findings. Trial funding source was an important determinant of these outcomes, with both academic and industry sponsors contributing to inefficiencies.

Ambient temperature and respiratory virus infection.

Respiratory viruses are important pediatric pathogens with pronounced seasonal patterns of circulation. Various hypotheses have been put forth to explain the seasonality of these infections, many involving environmental factors. This review summarizes the effect of temperature on the epidemicity of respiratory viruses, with an emphasis on epidemiological findings from large-scale metanalyses, laboratory-derived data using animal models and possible mechanisms to account for viral seasonality.

Chimeric hemagglutinin influenza virus vaccine constructs elicit broadly protective stalk-specific antibodies.

Current influenza virus vaccine strategies stimulate immune responses toward the globular head domain of the hemagglutinin protein in order to inhibit key steps of the virus life cycle. Because this domain is highly variable across strains, new vaccine formulations are required in most years. Here we demonstrate a novel vaccine strategy that generates immunity to the highly conserved stalk domain by using chimeric hemagglutinin constructs that express unique head and stalk combinations. By repeatedly immunizing mice with constructs that expressed the same stalk but an irrelevant head, we specifically stimulated a stalk-directed response that provided broad-based heterologous and heterosubtypic immunity in mice. Notably, our vaccination scheme provides a universal vaccine approach that protects against challenge with an H5 subtype virus. Furthermore, through in vivo studies using passively transferred antibodies or depletion of CD8(+) T cells, we demonstrated the critical role that humoral mechanisms of immunity play in the protection observed. The present data suggest that a vaccine strategy based on the stalk domain of the hemagglutinin protein could be used in humans to broadly protect against a variety of influenza virus subtypes.

Toward a universal influenza virus vaccine: prospects and challenges.

Current influenza virus vaccines are annually reformulated to elicit protection by generating an immune response toward the virus strains that are predicted to circulate in the upcoming influenza season. These vaccines provide limited protection in cases of antigenic mismatch, when the vaccine and the circulating viral strains differ. The emergence of unexpected pandemic viruses presents an additional challenge to vaccine production. To increase influenza virus preparedness, much work has been dedicated to the development of a universal vaccine. Focusing on regions of viral proteins that are highly conserved across virus subtypes, vaccine strategies involving the matrix 2 protein, stalk domain of the hemagglutinin, and multivalent approaches have provided broad-based protection in animal models and show much promise. This review summarizes the most encouraging advances in the field with a focus on novel vaccine designs that have yielded promising preclinical and clinical data.

A carboxy-terminal trimerization domain stabilizes conformational epitopes on the stalk domain of soluble recombinant hemagglutinin substrates.

Recently, a new class of broadly neutralizing anti-influenza virus antibodies that target the stalk domain of the viral hemagglutinin was discovered. As such, induction, isolation, characterization, and quantification of these novel antibodies has become an area of intense research and great interest. Since most of these antibodies bind to conformational epitopes, the structural integrity of hemagglutinin substrates for the detection and quantification of these antibodies is of high importance. Here we evaluate the binding of these antibodies to soluble, secreted hemagglutinins with or without a carboxy-terminal trimerization domain based on the natural trimerization domain of T4 phage fibritin. The lack of such a domain completely abolishes binding to group 1 hemagglutinins and also affects binding to group 2 hemagglutinins. Additionally, the presence of a trimerization domain positively influences soluble hemagglutinin stability during expression and purification. Our findings suggest that a carboxy-terminal trimerization domain is a necessary requirement for the structural integrity of stalk epitopes on recombinant soluble influenza virus hemagglutinin.

NS1-truncated live attenuated virus vaccine provides robust protection to aged mice from viral challenge.

Immunological changes associated with age contribute to the high rates of influenza virus morbidity and mortality in the elderly. Compounding this problem, aged individuals do not respond to vaccination as well as younger, healthy adults. Efforts to increase protection to this demographic group are of utmost importance, as the proportion of the population above the age of 65 is projected to increase in the coming decade. Using a live influenza virus with a truncated nonstructural protein 1 (NS1), we are able to stimulate cellular and humoral immune responses of aged mice comparable to levels seen in young mice. Impressively, a single vaccination provided protection following stringent lethal challenge in aged mice.

Hemagglutinin Stalk-Reactive Antibodies Are Boosted following Sequential Infection with Seasonal and Pandemic H1N1 Influenza Virus in Mice.

Previously, it has been shown that infection in humans with the pandemic swine influenza virus induces antibodies with specificity to the stalk domain of the viral hemagglutinin. Following the generation of these data, we sought to recapitulate these findings in the mouse model by sequential influenza virus infection. Mice that were inoculated with a seasonal influenza H1N1 virus followed by infection with a pandemic H1N1 strain produced higher antihemagglutinin stalk antibody titers than mice sequentially infected with drifted seasonal strains. In order to achieve antibody titers of comparable magnitude using sequential infection, mice had to be infected with 100- to 1,000-fold more of the drifted seasonal virus. The antistalk antibodies produced by these infections were influenza virus neutralizing, which illustrates the utility of the mouse model in which to study this interaction between virus and host.

Enhanced mammalian transmissibility of seasonal influenza A/H1N1 viruses encoding an oseltamivir-resistant neuraminidase.

Between 2007 and 2009, oseltamivir resistance developed among seasonal influenza A/H1N1 (sH1N1) virus isolates at an exponential rate, without a corresponding increase in oseltamivir usage. We hypothesized that the oseltamivir-resistant neuraminidase (NA), in addition to being relatively insusceptible to the antiviral effect of oseltamivir, might confer an additional fitness advantage on these viruses by enhancing their transmission efficiency among humans. Here we demonstrate that an oseltamivir-resistant clinical isolate, an A/Brisbane/59/2007(H1N1)-like virus isolated in New York State in 2008, transmits more efficiently among guinea pigs than does a highly similar, contemporaneous oseltamivir-sensitive isolate. With reverse genetics reassortants and point mutants of the two clinical isolates, we further show that expression of the oseltamivir-resistant NA in the context of viral proteins from the oseltamivir-sensitive virus (a 7:1 reassortant) is sufficient to enhance transmissibility. In the guinea pig model, the NA is the critical determinant of transmission efficiency between oseltamivir-sensitive and -resistant Brisbane/59-like sH1N1 viruses, independent of concurrent drift mutations that occurred in other gene products. Our data suggest that the oseltamivir-resistant NA (specifically, one or both of the companion mutations, H275Y and D354G) may have allowed resistant Brisbane/59-like viruses to outtransmit sensitive isolates. These data provide in vivo evidence of an evolutionary mechanism that would explain the rapidity with which oseltamivir resistance achieved fixation among sH1N1 isolates in the human reservoir.

Environmental factors affecting the transmission of respiratory viruses.

Many viruses are capable of infecting the human respiratory tract to cause disease. These viruses display various transmission patterns among humans; however, they all share the ability to transmit from person to person, and their human transmissibility is influenced by the environment in which pathogen and host meet. This review aims to summarize recent and significant observations regarding the impact of environmental factors such as weather and climate, humidity, temperature, and airflow on the transmission of human respiratory viruses. Where possible, knowledge gaps that require further scientific study will be identified.

Influenza viruses expressing chimeric hemagglutinins: globular head and stalk domains derived from different subtypes.

The influenza virus hemagglutinin molecule possesses a globular head domain that mediates receptor binding and a stalk domain at the membrane-proximal region. We generated functional influenza viruses expressing chimeric hemagglutinins encompassing a variety of globular head and stalk combinations, not only from different hemagglutinin subtypes but also from different hemagglutinin phylogenetic groups. These chimeric recombinant viruses possess growth properties similar to those of wild-type influenza viruses and can be used as reagents to measure domain-specific antibodies in virological and immunological assays.

Attenuated influenza virus construct with enhanced hemagglutinin protein expression.

Influenza A viruses encoding an altered viral NS1 protein have emerged as promising live attenuated vaccine platforms. A carboxy-terminal truncation in the NS1 protein compromises its interferon antagonism activity, making these viruses attenuated in the host yet still able to induce protection from challenge with wild-type viruses. However, specific viral protein expression by NS1-truncated viruses is known to be decreased in infected cells. In this report, we show that recombinant H5N1 and H1N1 influenza viruses encoding a truncated NS1 protein expressed lower levels of hemagglutinin (HA) protein in infected cells than did wild-type viruses. This reduction in HA protein expression correlated with a reduction in HA mRNA levels in infected cells. NS1 truncation affected the expression of HA protein but not that of the nucleoprotein (NP). This segment specificity was mapped to the terminal sequences of their specific viral RNAs. Since the HA protein is the major immunogenic component in influenza virus vaccines, we sought to restore its expression levels in NS1-truncated viruses in order to improve their vaccine efficacy. For this purpose, we generated an NS1-truncated recombinant influenza A/Puerto Rico/8/34 (rPR8) virus carrying the G3A C8U "superpromoter" mutations in the HA genomic RNA segment. This strategy retained the attenuation properties of the recombinant virus but enhanced the expression level of HA protein in infected cells. Finally, mice immunized with rPR8 viruses encoding a truncated NS1 protein and carrying the G3A C8U mutations in the HA segment demonstrated enhanced protection from wild-type virus challenge over that for mice vaccinated with an rPR8 virus encoding the truncated NS1 protein alone.

Transmission of influenza B viruses in the guinea pig.

Epidemic influenza is typically caused by infection with viruses of the A and B types and can result in substantial morbidity and mortality during a given season. Here we demonstrate that influenza B viruses can replicate in the upper respiratory tract of the guinea pig and that viruses of the two main lineages can be transmitted with 100% efficiency between inoculated and naïve animals in both contact and noncontact models. Our results also indicate that, like in the case for influenza A virus, transmission of influenza B viruses is enhanced at colder temperatures, providing an explanation for the seasonality of influenza epidemics in temperate climates. We therefore present, for the first time, a small animal model with which to study the underlying mechanisms of influenza B virus transmission.

Hemagglutinin stalk antibodies elicited by the 2009 pandemic influenza virus as a mechanism for the extinction of seasonal H1N1 viruses.

After the emergence of pandemic influenza viruses in 1957, 1968, and 2009, existing seasonal viruses were observed to be replaced in the human population by the novel pandemic strains. We have previously hypothesized that the replacement of seasonal strains was mediated, in part, by a population-scale boost in antibodies specific for conserved regions of the hemagglutinin stalk and the viral neuraminidase. Numerous recent studies have shown the role of stalk-specific antibodies in neutralization of influenza viruses; the finding that stalk antibodies can effectively neutralize virus alters the existing dogma that influenza virus neutralization is mediated solely by antibodies that react with the globular head of the viral hemagglutinin. The present study explores the possibility that stalk-specific antibodies were boosted by infection with the 2009 H1N1 pandemic virus and that those antibodies could have contributed to the disappearance of existing seasonal H1N1 influenza virus strains. To study stalk-specific antibodies, we have developed chimeric hemagglutinin constructs that enable the measurement of antibodies that bind the hemagglutinin protein and neutralize virus but do not have hemagglutination inhibition activity. Using these chimeric hemagglutinin reagents, we show that infection with the 2009 pandemic H1N1 virus elicited a boost in titer of virus-neutralizing antibodies directed against the hemagglutinin stalk. In addition, we describe assays that can be used to measure influenza virus-neutralizing antibodies that are not detected in the traditional hemagglutination inhibition assay.

The M segment of the 2009 new pandemic H1N1 influenza virus is critical for its high transmission efficiency in the guinea pig model.

A remarkable feature of the 2009 pandemic H1N1 influenza virus is its efficient transmissibility in humans compared to that of precursor strains from the triple-reassortant swine influenza virus lineage, which cause only sporadic infections in humans. The viral components essential for this phenotype have not been fully elucidated. In this study, we aimed to determine the viral factors critical for aerosol transmission of the 2009 pandemic virus. Single or multiple segment reassortments were made between the pandemic A/California/04/09 (H1N1) (Cal/09) virus and another H1N1 strain, A/Puerto Rico/8/34 (H1N1) (PR8). These viruses were then tested in the guinea pig model to understand which segment of Cal/09 virus conferred transmissibility to the poorly transmissible PR8 virus. We confirmed our findings by generating recombinant A/swine/Texas/1998 (H3N2) (sw/Tx/98) virus, a representative triple-reassortant swine virus, containing segments of the Cal/09 virus. The data showed that the M segment of the Cal/09 virus promoted aerosol transmissibility to recombinant viruses with PR8 and sw/Tx/98 virus backgrounds, suggesting that the M segment is a critical factor supporting the transmission of the 2009 pandemic virus.

The DBA.2 mouse is susceptible to disease following infection with a broad, but limited, range of influenza A and B viruses.

We assessed the relative susceptibilities to disease of the DBA.2 and C57BL/6 mouse models upon infection with a range of influenza A and B viruses. DBA.2 mice were more susceptible to disease upon inoculation with human H1N1 influenza A virus strains, several swine influenza viruses, and influenza B viruses but were not overtly susceptible to infection with human seasonal H3N2 strains. Hemagglutination inhibition and immunoglobulin isotype profiling indicated that DBA.2 and C57BL/6 mice generate comparable humoral responses upon equivalent 50% mouse lethal dose (MLD(50)) challenges with influenza virus. Our data demonstrate the utility of DBA.2 mice for the elucidation of influenza virus pathogenicity determinants and the testing of influenza vaccines.

Vaccination with a synthetic peptide from the influenza virus hemagglutinin provides protection against distinct viral subtypes.

Current influenza virus vaccines protect mostly against homologous virus strains; thus, regular immunization with updated vaccine formulations is necessary to guard against the virus' hallmark remodeling of regions that mediate neutralization. Development of a broadly protective influenza vaccine would mark a significant advance in human infectious diseases research. Antibodies with broad neutralizing activity (nAbs) against multiple influenza virus strains or subtypes have been reported to bind the stalk of the viral hemagglutinin, suggesting that a vaccine based on this region could elicit a broadly protective immune response. Here we describe a hemagglutinin subunit 2 protein (HA2)-based synthetic peptide vaccine that provides protection in mice against influenza viruses of the structurally divergent subtypes H3N2, H1N1, and H5N1. The immunogen is based on the binding site of the recently described nAb 12D1, which neutralizes H3 subtype viruses, demonstrates protective activity in vivo, and, in contrast to a majority of described nAbs, appears to bind to residues within a single α-helical portion of the HA2 protein. Our data further demonstrate that the specific design of our immunogen is integral in the induction of broadly active anti-hemagglutinin antibodies. These results provide proof of concept for an HA2-based influenza vaccine that could diminish the threat of pandemic influenza disease and generally reduce the significance of influenza viruses as human pathogens.

Broadly protective monoclonal antibodies against H3 influenza viruses following sequential immunization with different hemagglutinins.

As targets of adaptive immunity, influenza viruses are characterized by the fluidity with which they respond to the selective pressure applied by neutralizing antibodies. This mutability of structural determinants of protective immunity is the obstacle in developing universal influenza vaccines. Towards the development of such vaccines and other immune therapies, our studies are designed to identify regions of influenza viruses that are conserved and that mediate virus neutralization. We have specifically focused on viruses of the H3N2 subtype, which have persisted as a principal source of influenza-related morbidity and mortality in humans since the pandemic of 1968. Three monoclonal antibodies have been identified that are broadly-neutralizing against H3 influenza viruses spanning 40 years. The antibodies react with the hemagglutinin glycoprotein and appear to bind in regions that are refractory to the structural variation required for viral escape from neutralization. The antibodies demonstrate therapeutic efficacy in mice against H3N2 virus infection and have potential for use in the treatment of human influenza disease. By mapping the binding region of one antibody, 12D1, we have identified a continuous region of the hemagglutinin that may act as an immunogen to elicit broadly protective immunity to H3 viruses. The anti-H3 monoclonal antibodies were identified after immunization of mice with the hemagglutinin of four different viruses (A/Hong Kong/1/1968, A/Alabama/1/1981, A/Beijing/47/1992, A/Wyoming/3/2003). This immunization schedule was designed to boost B cells specific for conserved regions of the hemagglutinin from distinct antigenic clusters. Importantly, our antibodies are of naturally occurring specificity rather than selected from cloned libraries, demonstrating that broad-spectrum humoral immunity to influenza viruses can be elicited in vivo.