Mucosal correlates of protection after influenza viral challenge of vaccinated and unvaccinated healthy volunteers

The induction of systemic antibody titers against hemagglutinin has long been the main focus of influenza vaccination strategies, but mucosal immunity has also been shown to play a key role in the protection against respiratory viruses. By vaccinating and challenging healthy volunteers, we demonstrated that inactivated influenza vaccine (IIV) modestly reduced the rate of influenza while predominantly boosting serum antibody titers against hemagglutinin (HA) and HA stalk, a consequence of the low neuraminidase (NA) content of IIV and the intramuscular route of administration. The viral challenge induced nasal and serum responses against both HA and NA. Correlations between mucosal IgA and serum IgG against specific antigens were low, whether before or after challenge, suggesting a compartmentalization of immune responses. Even so, volunteers who developed viral shedding for multiple days had lower baseline titers across both systemic and mucosal compartments as compared to those with no shedding or a single day of shedding. Regression analysis showed that pre-challenge HA inhibition titers were the most consistent correlate of protection across clinical outcomes combining shedding and symptoms, with NA inhibition titers and HA IgG levels only predicting the duration of shedding. Despite the inclusion of data from multiple binding and functional antibody assays against HA and NA performed on both serum and nasal samples, multivariate models were unable to account for the variability in outcomes, emphasizing our imperfect understanding of immune correlates in influenza and the importance of refining models with assessments of innate and cellular immune responses.IMPORTANCEThe devastating potential of influenza has been well known for over 100 years. Despite the development of vaccines since the middle of the 20th century, influenza continues to be responsible for substantial global morbidity and mortality. To develop next-generation vaccines with enhanced effectiveness, we must synthesize our understanding of the complex immune mechanisms culminating in protection. Our study outlines the differences in immune responses to influenza vaccine and influenza infection, identifying potential gaps in vaccine-induced immunity, particularly at the level of the nasal mucosa. Furthermore, this research underscores the need to refine our imperfect models while recognizing potential pitfalls in past and future attempts to identify and measure correlates of protection.

Dynamics of SARS-CoV-2 Seroprevalence in a Large US population Over a Period of 12 Months

Due to a combination of asymptomatic or undiagnosed infections, the proportion of the United States population infected with SARS-CoV-2 was unclear from the beginning of the pandemic. We previously established a platform to screen for SARS-CoV-2 positivity across a representative proportion of the US population, from which we reported that almost 17 million Americans were estimated to have had undocumented infections in the Spring of 2020. Since then, vaccine rollout and prevalence of different SARS-CoV-2 variants have further altered seropositivity trends within the United States population. To explore the longitudinal impacts of the pandemic and vaccine responses on seropositivity, we re-enrolled participants from our baseline study in a 6- and 12- month follow-up study to develop a longitudinal antibody profile capable of representing seropositivity within the United States during a critical period just prior to and during the initiation of vaccine rollout. Initial measurements showed that, since July 2020, seropositivity elevated within this population from 4.8% at baseline to 36.2% and 89.3% at 6 and 12 months, respectively. We also evaluated nucleocapsid seropositivity and compared to spike seropositivity to identify trends in infection versus vaccination relative to baseline. These data serve as a window into a critical timeframe within the COVID-19 pandemic response and serve as a resource that could be used in subsequent respiratory illness outbreaks.

505. Mucosal and Systemic Humoral Immunity Differences between Sexes during Influenza Vaccination and Viral Challenge

Background

In previous influenza challenge studies we observed that the incidence of influenza symptoms was higher in women than in men, and that women experience more symptoms overall. Women also demonstrated lower neuraminidase (NA) inhibition (NAI) antibody titers than men after challenge and regression analysis suggested that NAI titers predict clinical outcomes. We sought to evaluate this using data from a more recent challenge study with more immunologically varied volunteers, while also assessing mucosal immunity.

Methods

We obtained mucosal and serum samples from healthy adults. Half underwent intramuscular quadrivalent influenza vaccination followed by influenza A (H1N1) intranasal challenge while others just challenge alone. Antibody titers and clinical outcomes between sexes were compared.

Results

No significant differences in shedding or symptom outcomes were observed between sexes. Similarly, no differences in systemic titers against NA or hemagglutinin (HA) were seen. Serum total IgG and IgA were also similar between sexes. Prior to vaccination, mucosal IgA titers were significantly lower against HA stalk and NA in women, but these differences disappeared after vaccination. In the unvaccinated group, lower nasal IgA titers were also seen in women pre-challenge. At 7 days post-challenge, differences in mucosal titers between sexes disappeared. However, at 56 days post-challenge, mucosal IgA titers against HA, HA stalk, and NA were all significantly lower in women.

Conclusion

In contrast to our previous findings, no differences in clinical outcomes or systemic NAI titers were observed between men and women, possibly due to differences in underlying immunity between study populations or the lower sample size in this study. However, mucosal differences were noted with women having lower mucosal titers than men against HA stalk and NA at baseline. While influenza vaccination and challenge eliminated differences in the short term, they reappeared 8 weeks after challenge, with all nasal IgA antibody titers (HA, HA stalk, and NA) lower in women. Further studies are necessary to understand the differences in influenza disease and immunity between sexes.

Disclosures

All Authors: No reported disclosures.

Sex Differences in Influenza: The Challenge Study Experience

BACKGROUND

Preclinical animal studies and retrospective human studies suggest that adult females have worse outcomes from influenza than males. Prospective studies in humans are missing.

METHODS

Data from 164 healthy volunteers who underwent Influenza A/California/04/2009/H1N1 challenge were compiled to compare differences between sexes. Baseline characteristics, including hormone levels, hemagglutination-inhibition (HAI) titers, neuraminidase-inhibition titers (NAI), and outcomes after challenge were compared. Linear and logistic regression models were built to determine significant predictor variables with respect to outcomes of interest.

RESULTS

Hemagglutination-inhibition (HAI) titers were similar between the sexes, but neuraminidase-inhibition titers (NAI) were higher in males than females at 4-weeks and 8-weeks post-challenge. Females were more likely to have symptoms (mean 0.96 vs 0.80, p=.003) and to have a higher number of symptoms (median 3 vs 4, p=.011) than males. Linear and logistic regression models showed that pre-challenge NAI titers, but not HAI titers or sex hormone levels, were predictive of all shedding and symptom outcomes of interest.

CONCLUSIONS

Females in our cohorts were more likely to be symptomatic and to have a higher number of symptoms than males. NAI titers predicted all outcomes of interest and may explain differential outcomes between the sexes.

Developing Treatment Guidelines During a Pandemic Health Crisis: Lessons Learned From COVID-19

The development of the National Institutes of Health (NIH) COVID-19 Treatment Guidelines began in March 2020 in response to a request from the White House Coronavirus Task Force. Within 4 days of the request, the NIH COVID-19 Treatment Guidelines Panel was established and the first meeting took place (virtually-as did subsequent meetings). The Panel comprises 57 individuals representing 6 governmental agencies, 11 professional societies, and 33 medical centers, plus 2 community members, who have worked together to create and frequently update the guidelines on the basis of evidence from the most recent clinical studies available. The initial version of the guidelines was completed within 2 weeks and posted online on 21 April 2020. Initially, sparse evidence was available to guide COVID-19 treatment recommendations. However, treatment data rapidly accrued based on results from clinical studies that used various study designs and evaluated different therapeutic agents and approaches. Data have continued to evolve at a rapid pace, leading to 24 revisions and updates of the guidelines in the first year. This process has provided important lessons for responding to an unprecedented public health emergency: Providers and stakeholders are eager to access credible, current treatment guidelines; governmental agencies, professional societies, and health care leaders can work together effectively and expeditiously; panelists from various disciplines, including biostatistics, are important for quickly developing well-informed recommendations; well-powered randomized clinical trials continue to provide the most compelling evidence to guide treatment recommendations; treatment recommendations need to be developed in a confidential setting free from external pressures; development of a user-friendly, web-based format for communicating with health care providers requires substantial administrative support; and frequent updates are necessary as clinical evidence rapidly emerges.

Undiagnosed SARS-CoV-2 seropositivity during the first 6 months of the COVID-19 pandemic in the United States

Asymptomatic SARS-CoV-2 infection and delayed implementation of diagnostics have led to poorly defined viral prevalence rates in the United States and elsewhere. To address this, we analyzed seropositivity in 9089 adults in the United States who had not been diagnosed previously with COVID-19. Individuals with characteristics that reflected the U.S. population (n = 27,716) were selected by quota sampling from 462,949 volunteers. Enrolled participants (n = 11,382) provided medical, geographic, demographic, and socioeconomic information and dried blood samples. Survey questions coincident with the Behavioral Risk Factor Surveillance System survey, a large probability-based national survey, were used to adjust for selection bias. Most blood samples (88.7%) were collected between 10 May and 31 July 2020 and were processed using ELISA to measure seropositivity (IgG and IgM antibodies against SARS-CoV-2 spike protein and the spike protein receptor binding domain). The overall weighted undiagnosed seropositivity estimate was 4.6% (95% CI, 2.6 to 6.5%), with race, age, sex, ethnicity, and urban/rural subgroup estimates ranging from 1.1% to 14.2%. The highest seropositivity estimates were in African American participants; younger, female, and Hispanic participants; and residents of urban centers. These data indicate that there were 4.8 undiagnosed SARS-CoV-2 infections for every diagnosed case of COVID-19, and an estimated 16.8 million infections were undiagnosed by mid-July 2020 in the United States.

Dissecting the Role of VicK Phosphatase in Aggregation and Biofilm Formation of Streptococcus mutans

VicRK (WalRK or YycFG) is a conserved 2-component regulatory system (TCS) that regulates cell division, cell wall biosynthesis, and homeostasis in low-GC Gram-positive bacteria. VicRK is also associated with biofilm formation of Streptococcus mutans on the tooth surface as it directly regulates the extracellular polysaccharide (EPS) synthesis. Of the 2 components, VicK possesses both autokinase and phosphatase activities, which regulate the phosphorylation and dephosphorylation of the regulator VicR in response to environmental cues. However, the dual mechanism of VicK as the autokinase/phosphatase in regulating S. mutans' responses is not well elucidated. Previously, it has been shown that the phosphatase activity depends on the PAS domain and residues in the DHp domain of VicK in S. mutans. Specifically, mutating proline at 222 in the PAS domain inhibits VicK phosphatase activity. We generated a VicK^P222A mutant to determine the level of VicR-P in the cytoplasm by Phos-tag sodium dodecyl sulfate polyacrylamide gel electrophoresis. We show that in VicK^P222A phosphatase, attenuation increased phosphorylated VicR (VicR-P) that downregulated glucosyltransferases, gtfBC, thereby reducing the synthesis of water-insoluble polysaccharides (WIS-EPS) in the biofilm. In addition, VicK^P222A presented as long-rod cells, reduced growth, and displayed asymmetrical division. A major adhesin of S. mutans, SpaP was downregulated in VicK^P222A, making it unable to agglutinate in saliva. In summary, we have confirmed that VicK phosphatase activity is critical to maintain optimal phosphorylation status of VicR in S. mutans, which is important for cell growth, cell division, EPS synthesis, and bacterial agglutination in saliva. Hence, VicK phosphatase activity may represent a promising target to modulate S. mutans' pathogenicity.

Mapping a Pandemic: SARS-CoV-2 Seropositivity in the United States

Asymptomatic SARS-CoV-2 infection and delayed implementation of diagnostics have led to poorly defined viral prevalence rates. To address this, we analyzed seropositivity in US adults who have not previously been diagnosed with COVID-19. Individuals with characteristics that reflect the US population (n = 11,382) and who had not previously been diagnosed with COVID-19 were selected by quota sampling from 241,424 volunteers (ClinicalTrials.gov NCT04334954). Enrolled participants provided medical, geographic, demographic, and socioeconomic information and 9,028 blood samples. The majority (88.7%) of samples were collected between May 10th and July 31st, 2020. Samples were analyzed via ELISA for anti-Spike and anti-RBD antibodies. Estimation of seroprevalence was performed by using a weighted analysis to reflect the US population. We detected an undiagnosed seropositivity rate of 4.6% (95% CI: 2.6 - 6.5%). There was distinct regional variability, with heightened seropositivity in locations of early outbreaks. Subgroup analysis demonstrated that the highest estimated undiagnosed seropositivity within groups was detected in younger participants (ages 18-45, 5.9%), females (5.5%), Black/African American (14.2%), Hispanic (6.1%), and Urban residents (5.3%), and lower undiagnosed seropositivity in those with chronic diseases. During the first wave of infection over the spring/summer of 2020 an estimate of 4.6% of adults had a prior undiagnosed SARS-CoV-2 infection. These data indicate that there were 4.8 (95% CI: 2.8-6.8) undiagnosed cases for every diagnosed case of COVID-19 during this same time period in the United States, and an estimated 16.8 million undiagnosed cases by mid-July 2020.

Influenza A Reinfection in Sequential Human Challenge: Implications for Protective Immunity and "Universal" Vaccine Development

BACKGROUND

Identification of correlates of protection against human influenza A virus infection is important in development of broadly protective ("universal") influenza vaccines. Certain assumptions underlie current vaccine developmental strategies, including that infection with a particular influenza A virus should offer long-term or lifelong protection against that strain, preventing reinfection. In this study we report observations made when 7 volunteers participated in sequential influenza challenge studies where they were challenged intranasally using the identical influenza A(H1N1)pdm09 virus approximately 1 year apart. We evaluate and describe the outcomes of these 7 rechallenge participants and discuss what these results may suggest about correlates of protection and development of more broadly protective influenza vaccines.

METHODS

Seven participants were enrolled in 2 viral challenge studies at 7.5- to 18.5-month intervals. Both challenge studies used the identical lot of influenza A (H1N1)pdm09 virus administered intranasally. We evaluated pre- and postchallenge hemagglutination inhibition, neuraminidase inhibition, and stalk antibody titers; peripheral blood leukocyte host gene expression response profiles; daily viral detection via nasal wash; and clinical signs and symptoms.

RESULTS

At least 3 of 7 participants demonstrated confirmed laboratory evidence of sequential infection, with 5 of 7 demonstrating clinical evidence.

CONCLUSIONS

The data presented in this report demonstrate that sequential infection with the identical influenza A virus can occur and suggest it may not be rare. These data raise questions about immune memory responses in an acute superficial respiratory mucosal infection and their implications in development of broadly protective influenza vaccines. Further investigation of these observations is warranted.

CLINICAL TRIALS REGISTRATION

NCT01646138; NCT01971255.

1524. Sex Differences in Influenza: The Challenge Study Experience

Background

Our understanding of the impact of biological sex on influenza-associated disease and the mechanisms that underpin it is still incomplete. Further investigation of sex-linked effects on influenza pathogenesis and clinical outcomes may help tailor vaccine strategies. Animal studies have shown female mice experience more symptoms than male mice during influenza infection. Similarly, human females of reproductive age have higher rates of influenza and influenza-related hospitalizations. However, data is sometimes conflicting and may be confounded by other important differences in baseline characteristics. Human challenge studies have demonstrated the importance of NAI titers as a correlate of protection and may also provide an ideal opportunity to study sex differences in a homogenous group of participants controlled for confounders.

Methods

Data from 168 volunteers who underwent Influenza A/California/04/2009/H1N1 challenge studies affiliated with NIAID’s LID Clinical Studies Unit were compiled to compare differences between sexes. Participants were included in the analysis if they received a challenge dose of virus of 10⁷ TCID50 and were excluded if they had received any vaccines or experimental therapy during the study period.

Results

Baseline differences between male and female participants were observed in NAI titers but not HAI titers or age. Outcomes of interest included presence of viral shedding/duration which were similar among sexes. However, symptom number and duration were higher among female participants (p=0.008 and p=0.045 respectively). Ongoing data analysis also shows females have lower post-challenge NAI titers than males.

Conclusion

Female participants in our H1N1 challenge studies had more symptoms and a longer duration of symptoms compared to their male counterparts. Differences in NAI titers may potentially explain the observed relationship between sex and symptoms associated with influenza.

Disclosures

All Authors: No reported disclosures

1522. Safety and Efficacy of CR6261 in an Influenza A H1N1 Healthy Human Challenge Model

Background

Influenza virus infections cause significant morbidity and mortality during yearly seasonal epidemics and during sporadic pandemics. It is imperative to identify new targets for vaccines and therapeutics. One such target is the relatively conserved stalk region of the influenza A hemagglutinin (HA) surface protein.

Methods

We conducted a randomized, double-blind, Phase II placebo-controlled trial of a monoclonal antibody that targets the HA stalk (CR6261) in a H1N1pdm09 healthy volunteer human challenge model. CR6261 was infused 24 hours after challenge with H1N1pdm09 and the primary efficacy outcome was area under the curve (AUC) of viral shedding.

Results

Between March 2015-May 2018, 104 healthy volunteers were enrolled and randomized with 91 undergoing influenza challenge, of which 49 participants (54%) received treatment with CR6261 and 42 participants (46%) received placebo. A mean of 1x10⁶ ng/mL of serum CR6261 was detected by 24 hours after infusion. Nasal CR6261 levels reached a peak mean of 5.97x10² ng/ml 2 days after infusion. There was no statistically significant difference in the primary outcome measure between the CR6261 group and placebo (median AUC 48.56 and 25.53 respectively, P=0.31). The severity of illness was compared between the two groups, and no significant difference was observed in number of symptoms, duration of symptoms, or FLU-PRO scores.

Conclusion

CR6261 had no statistically significant effect on AUC of viral shedding, and no clinically significant effect on overall influenza disease. Preexisting anti-neuraminidase (NA) antibody titers were most predictive of reduced influenza disease. Nasal CR6261 levels were much lower compared to serum, which may be a factor in the limited effect of CR6261 on this upper respiratory infection. These results suggest that a monoclonal anti-stalk approach to prevent or treat influenza infection may have limited efficacy. Future approaches should consider including and evaluating anti-stalk antibodies as part of a multi-faceted strategy rather than as a standalone therapeutic or vaccine strategy.

Funding

This study was funded in part by the intramural program of NIAID, NIH, by the NCI Contract No. 75N910D00024, Task Order No. 75N91019F00130, and through a CRADA with Janssen Infectious Diseases and Vaccines.

Disclosures

Amy Lwin, RN, BSN, Janssen Pharmaceutical Company of J&J (Employee) Jerald Sadoff, MD, Janssen Pharmaceutical Company of J&J (Employee)

Safety and Efficacy of CR6261 in an Influenza A H1N1 Healthy Human Challenge Model

BACKGROUND

It is imperative to identify new targets for improved vaccines and therapeutics against influenza and one such target is the relatively conserved stalk region of the influenza A hemagglutinin (HA) surface protein.

METHODS

We conducted a randomized, double-blind, Phase II placebo-controlled trial of a monoclonal antibody that targets the HA stalk (CR6261) in a H1N1pdm09 healthy volunteer human challenge model. A single 50mg/kg dose of CR6261 was infused 24 hours after challenge and the primary efficacy outcome was area under the curve of viral RNA detection over time.

RESULTS

Ninety-one healthy volunteers were randomized and underwent influenza challenge; 49 received CR6261 and 42 placebo. CR6261 had no statistically significant effect on AUC (AUC 48.56 log (copies/mL) x days, IQR 202 vs. AUC 25.53 log (copies/mL) x days, IQR 155), P=0.315), and no clinically significant effect on influenza disease measures including number of symptoms, duration of symptoms, or FLU-PRO scores. Preexisting anti-NA antibody titers were most predictive of reduced influenza disease. CR6261 reached a mean peak serum concentration of 1x10 6 ng/ml 15 minutes after infusion, and a mean peak of 5.97x10 2 ng/ml in the nasal mucosa 2-3 days after infusion.

CONCLUSIONS

The results of this study suggest that a monoclonal anti-stalk approach to prevent or treat influenza infection may be limited in efficacy. Future approaches should consider including and evaluating anti-stalk antibodies as part of a multi-faceted strategy rather than as a standalone therapeutic.

A Dose-finding Study of a Wild-type Influenza A(H3N2) Virus in a Healthy Volunteer Human Challenge Model

BACKGROUND

The development of vaccines and therapeutics has relied on healthy volunteer influenza challenge studies. A validated human infection model with wild-type A(H1N1)pdm09 was reported previously. Our objective was to characterize a wild-type influenza A/Bethesda/MM1/H3N2 challenge virus in healthy volunteers.

METHODS

Participants received a single dose of a cell-based, reverse-genetics, Good Manufacturing Practices-produced wild-type influenza A(H3N2)2011 virus intranasally and were isolated at the National Institutes of Health Clinical Center for ≥9 days. Dose escalation was performed from 104 to 107 TCID50 (50% tissue culture infectious dose). Viral shedding and clinical disease were evaluated daily.

RESULTS

Of 37 participants challenged, 16 (43%) had viral shedding and 27 (73%) developed symptoms, with 12 (32%) participants experiencing mild to moderate influenza disease (MMID), defined as shedding and symptoms. Only participants receiving 106 and 107 TCID50 experienced MMID at 44% and 40%, respectively. Symptom severity peaked on day 3, whereas most viral shedding occurred 1-2 days after challenge. Only 10 (29%) participants had a ≥4-fold rise in hemagglutination inhibition antibody titer after challenge.

CONCLUSIONS

The A/Bethesda/MM1/H3N2 challenge virus safely induced MMID in healthy volunteers, but caused less MMID than the A(H1N1)pdm09 challenge virus even at the highest dose. There was less detection of shedding though the incidence of symptoms was similar to A(H1N1)pdm09. Fewer serum anti-hemagglutinin (HA) antibody responses with less MMID indicate that preexisting immunity factors other than anti-HA antibody may limit shedding in healthy volunteers. This A/Bethesda/MM1/H3N2 challenge virus can be utilized in future studies to further explore pathogenesis and immunity and to evaluate vaccine candidates.

CLINICAL TRIALS REGISTRATION

NCT02594189.

Pre-existing immunity to influenza virus hemagglutinin stalk might drive selection for antibody-escape mutant viruses in a human challenge model

The conserved region of influenza hemagglutinin (HA) stalk (or stem) has gained attention as a potent target for universal influenza vaccines^1-5. Although the HA stalk region is relatively well conserved, the evolutionarily dynamic nature of influenza viruses⁶ raises concerns about the possible emergence of viruses carrying stalk escape mutation(s) under sufficient immune pressure. Here we show that immune pressure on the HA stalk can lead to expansion of escape mutant viruses in study participants challenged with a 2009 H1N1 pandemic influenza virus inoculum containing an A388V polymorphism in the HA stalk (45% wild type and 55% mutant). High level of stalk antibody titers was associated with the selection of the mutant virus both in humans and in vitro. Although the mutant virus showed slightly decreased replication in mice, it was not observed in cell culture, ferrets or human challenge participants. The A388V mutation conferred resistance to some of the potent HA stalk broadly neutralizing monoclonal antibodies (bNAbs). Co-culture of wild-type and mutant viruses in the presence of either a bNAb or human serum resulted in rapid expansion of the mutant. These data shed light on a potential obstacle for the success of HA-stalk-targeting universal influenza vaccines-viral escape from vaccine-induced stalk immunity.

Safety and immunogenicity of a mosquito saliva peptide-based vaccine: a randomised, placebo-controlled, double-blind, phase 1 trial

BACKGROUND

In animal models, immunity to mosquito salivary proteins protects animals against mosquito-borne disease. These findings provide a rationale to vaccinate against mosquito saliva instead of the pathogen itself. To our knowledge, no vector salivary protein-based vaccine has been tested for safety and immunogenicity in humans. We aimed to assess the safety and immunogenicity of Anopheles gambiae saliva vaccine (AGS-v), a peptide-based vaccine derived from four A gambiae salivary proteins, in humans.

METHODS

In this randomised, placebo-controlled, double-blind, phase 1 trial, participants were enrolled at the National Institutes of Health Clinical Center in Bethesda, MD, USA. Participants were eligible if they were healthy adults, aged 18-50 years with no history of severe allergic reactions to mosquito bites. Participants were randomly assigned (1:1:1), using block randomisation and a computer-generated randomisation sequence, to treatment with either 200 nmol of AGS-v vaccine alone, 200 nmol of AGS-v with adjuvant (Montanide ISA 51), or sterile water as placebo. Participants and clinicians were masked to treatment assignment. Participants were given a subcutaneous injection of their allocated treatment at day 0 and day 21, followed by exposure to feeding by an uninfected Aedes aegypti mosquito at day 42 to assess subsequent risk to mosquito bites in a controlled setting. The primary endpoints were safety and immunogenicity at day 42 after the first immunisation. Participants who were given at least one dose of assigned treatment were assessed for the primary endpoints and analysis was by intention to treat. The trial was registered with ClinicalTrials.gov, NCT03055000, and is closed for accrual.

FINDINGS

Between Feb 15 and Sept 10, 2017, we enrolled and randomly assigned 49 healthy adult participants to the adjuvanted vaccine (n=17), vaccine alone (n=16), or placebo group (n=16). Five participants did not complete the two-injection regimen with mosquito feeding at day 42, but were included in the safety analyses. No systemic safety concerns were identified; however, one participant in the adjuvanted vaccine group developed a grade 3 erythematous rash at the injection site. Pain, swelling, erythema, and itching were the most commonly reported local symptoms and were significantly increased in the adjuvanted vaccine group compared with both other treatment groups (nine [53%] of 17 participants in the adjuvanted vaccine group, two [13%] of 16 in the vaccine only group, and one [6%] of 16 in the placebo group; p=0·004). By day 42, participants who were given the adjuvanted vaccine had a significant increase in vaccine-specific total IgG antibodies compared with at baseline than did participants who were give vaccine only (absolute difference of log₁₀-fold change of 0·64 [95% CI 0·39 to 0·89]; p=0·0002) and who were given placebo (0·62 [0·34 to 0·91]; p=0·0001). We saw a significant increase in IFN-γ production by peripheral blood mononuclear cells at day 42 in the adjuvanted vaccine group compared with in the placebo group (absolute difference of log₁₀ ratio of vaccine peptide-stimulated vs negative control 0·17 [95% CI 0·061 to 0·27]; p=0·009) but we saw no difference between the IFN-γ production in the vaccine only group compared with the placebo group (0·022 [-0·072 to 0·116]; p=0·63).

INTERPRETATION

AGS-v was well tolerated, and, when adjuvanted, immunogenic. These findings suggest that vector-targeted vaccine administration in humans is safe and could be a viable option for the increasing burden of vector-borne disease.

FUNDING

Office of the Director and the Division of Intramural Research at the National Institute of Allergy and Infectious Diseases, and National Institutes of Health.

Universal coronavirus vaccines: the time to start is now

The continued explosive spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite aggressive public health measures has triggered an unprecedented international vaccine effort. However, correlates of protection, which can help guide intelligent vaccine design, are not known for SARS-CoV-2. Research on influenza immunity and vaccine development may provide valuable lessons for coronavirus efforts, especially considering similarities in rapid evolutionary potential. The apparent inevitability of future novel coronavirus outbreaks must prompt work on a universal coronavirus vaccine.

2750. Sequential Influenza A H1N1 and Influenza A H3N2 Challenge Infections in Healthy Volunteers

Background

Seasonal influenza causes significant annual morbidity and mortality. The effects of yearly exposures on immunity are not clear and recent observations have demonstrated that long lasting protection against a matched strain may not naturally occur. The 2018–2019 influenza season consisted of an initial peak of H1N1 infections followed by a wave of H3N2 infections. These consecutive waves raise questions about how influenza immunity is affected by sequential exposure to different influenza strains. Challenge studies provide a unique opportunity to study this phenomenon. Here we describe a subset of participants who were sequentially infected in two separate challenge studies with wild-type H1N1 and H3N2 viruses.

Methods

Healthy volunteers completed two sequential influenza challenge studies at the NIH Clinical Center. Participants were inoculated with reverse genetics, cell-based, GMP wild-type influenza viruses, A(H1N1)pdm09 and A(H3N2) strains. Participants remained isolated in the hospital for a minimum of 9 days and were monitored daily for viral shedding and clinical symptoms. After discharge, participants were followed for 2 months.

Results

Between 2014 and 2017, 14 healthy volunteers were exposed to Influenza A(H1N1) and Influenza A(H3N2). Time between infections ranged from 2 months to 2 years. Thirteen (93%) participants developed confirmed influenza infection after H1N1 challenge and 9 (64%) after H3N2 challenge. Eight (57%) participants developed confirmed infections after both exposures. Variable degrees of symptoms, shedding, and disease severity were observed. Systemic antibody responses to the HA and NA of both H1N1 and H3N2 varied over time during these sequential infections.

Conclusion

More than half of all participants who completed 2 sequential H1N1 and H3N2 challenge studies demonstrated confirmed infection to both viruses. These sequential infections had varying effects on the disease experienced and the immunity that developed after infection. These observations are important in understanding the impact of sequential exposures on influenza immunity.

Disclosures

All authors: No reported disclosures.

Deep sequencing of 2009 influenza A/H1N1 virus isolated from volunteer human challenge study participants and natural infections

Nasal wash samples from 15 human volunteers challenged with GMP manufactured influenza A/California/04/2009(H1N1) and from 5 naturally infected influenza patients of the 2009 pandemic were deep sequenced using viral targeted hybridization enrichment. Ten single nucleotide polymorphism (SNP) positions were found in the challenge virus. Some of the nonsynonymous changes in the inoculant virus were maintained in some challenge participants, but not in others, indicating that virus is evolving away from the Vero cell adapted inoculant, for example SNPs in the neuraminidase. Many SNP sites in challenge patients and naturally infected patients were found, many not identified previously. The SNPs identified, and phylogenetic analyses, showed that intrahost evolution of the virus are different in challenge participants and naturally infected patients. This study, using hybridization enrichment without PCR, provided an accurate and unbiased assessment of differential intrahost viral evolution from a uniform influenza inoculant in humans and comparison to naturally infected patients.

Abstract P6-17-15: Evaluating preclinical efficacy of anti-HER2 drug combinations using ER+/HER2 mutant models

Background

Until recently, HER2 gene amplification was the only mechanism of HER2 activation recognized. However, activating HER2 mutations have been noted in different cancer types. A trials of HER2 mutant breast cancer and the subsequent SUMMIT trial data have shown that monotherapy with the pan-HER drug neratinib as showed clinical efficacy, but with poor response durability. This study therefore investigates the preclinical efficacy of anti HER2 agents alone or in combination with endocrine therapy agents or in combination with CDK4/6 inhibitors using ER+/HER2 mutant cell lines and ex vivo HER2 mutant patient derived xenograft (PDX) model to define a more effective treatment approach.

Methods

ER+ breast cancer cell lines (T47D and MCF7) stably expressing HER2V777L, and ER+/HER2 mutant PDX model (HER2G778_P780 dup) were used to examine HER2 signaling and drug responses. Signaling downstream mutant HER2 was examined by immunoblot analysis. Effects of neratinib alone, neratinib + fulvestrant, and neratinib + abemaciclib on cell growth were examined in ER+/HER2 mutant cell lines and in an ex vivo HER2G778_P780 dup.

Results

We found that MCF7/T47D cells expressing HER2V777L and HER2G778_P780 dup PDX tumors showed strongly activated autophosphorylation of HER2 and increased expression of CDK4, CDK6, phospho-Rb, and cyclin D1 as compared to MCF7/T47D cells expressing HER2WT or ER+/non-HER2mut PDX modes, suggesting that HER2 mutations preferentially depend on CDK4/6 signaling for cell growth. Additionally, we showed that activating MCF7 HER2 V777L cause resistance to endocrine therapy treatment (fulvestrant IC50 >5μM). Further, we show that neratinib alone is effective at higher concentrations (IC50 < 2μM) in MCF7/HER2 V777L cells. We also demonstrate that abemaciclib alone exhibited moderate activity against MCF7 HER2 V777L cells (IC50 < 0.4μM) and additional activity in combination with neratinib (IC50 < 0.06μM) was seen. Moreover, ex vivo HER2 G778_P780 dup cells are relatively resistant to fulvestrant alone (IC50 < 0.2μM), neratinib alone (IC50 < 0.006μM), abemaciclib alone (IC50 < 0.04μM), and neratinib in combination with abemaciclib (IC50 < 0.005μM), suggesting that patients harboring ER+/HER2-mutant tumors may benefit from neratinib in combination with abemaciclib.

Conclusion

These preclinical data suggest that neratinib monotherapy may not be effective to treat ER+/HER2 mutant patients and we propose that simultaneous targeting of both HER2 and the CDK4/6 axis will be required for effective treatment of ER+ breast cancers harboring HER2 activating mutations.

Citation Format: Kavuri SM, Devarakonda V, Williams LC, Seker S, Lei JT, Singh P, Han A, Anurag M, Holloway KR, Welm AL, Ellis MJ. Evaluating preclinical efficacy of anti-HER2 drug combinations using ER+/HER2 mutant models [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-15.

Abstract P5-08-01: DPYSL3 modulates mitosis, migration and epithelial to mesenchymal transition in claudin-low breast cancer

Proteogenomics is the field of integrating data from mass spectrometry-based shotgun proteomics, and phosphoproteomics into next-generation RNA and DNA sequencing data analysis pipelines that promises new insights into cancer biology and therapeutic targeting. As well as analyses of clinical samples for disease phenotype association analysis, the application of proteogenomics to model systems also has considerable potential. A Clinical Proteomic Tumor Analysis Consortium (CPTAC) proteogenomic analysis prioritized dihydropyrimidinase-like-3 (DPYSL3) as a multi-level (RNA/Protein/Phosphoprotein) expression outlier specific to the Claudin-Low (CLOW) subset of triple negative breast cancers. A Pubmed informatics tool indicated a paucity of data in the context of breast cancer which further prioritized DPYSL3 for study.

DPYSL3 was identified as a protein that is regulated during neuronal differentiation in the cerebral cortex and in neuronal cell lines and plays a role in regulating neurite outgrowth somehow through an association with vesicles in the growth cone. In addition, DPYSL3 expression has been observed in several malignant tumors, including prostate cancer, pancreatic cancer, gastric cancer and neuroblastoma. DPYSL3 is reported to play a role in cell migration and metastasis suppression in prostate cancer. However, in pancreatic cancer, DPYSL3 is positively associated with liver metastasis and poor outcome.

DPYSL3 knock-down in DPYSL3 (+) CLOW cell lines demonstrated reduced proliferation, yet enhanced motility and increased expression of Epithelial to Mesenchymal Transition (EMT) markers suggesting that DPYSL3 is a multi-functional signaling modulator. Slower proliferation in DPYSL3 (-) CLOW cells was associated with accumulation of multi-nucleated cells indicating a mitotic defect that was associated with a collapse of the vimentin (VIM) microfilament networkinduced by VIM hyperphosphorylation. On the other hand, DPYSL3 suppressed the expression of EMT regulators TWIST and SNAIL and opposed p21 activated kinase 2 (PAK2) dependent migration, but these EMT regulators in turn induced DPYSL3 expression, suggesting DPYSL3 participates in negative feedback in EMT. Cell migration in DPYSL3 (-) cells correlated with increased phosphorylation of PAK2 on Ser20 and was sensitive to PAK2 siRNA and pharmacological PAK inhibition.Immunoprecipitation and mass spectrometry-based proteomics or western blotting strongly suggests that PAKs interact such that DPYSL3 may function as a direct negative regulator of PAK family kinases. Thus, a PAK inhibitor could potentially mitigate increase migration as an adverse effect of DPYSL3 suppression.

In conclusion, DPYSL3 is a remarkable multifunctional signaling scaffold that should be examined further to provide insights into the stem cell-like state of claudin-low breast cancers, particularly in terms of their cell cycle dependencies, migratory activity and capacity for EMT.

Citation Format: Matsunuma R, Chan DW, Kim B-J, Singh P, Han A, Saltzman A, Cheng C, Lei JT, Sahin E, Leng M, Fan C, Perou CM, Malovannaya A, Ellis MJ. DPYSL3 modulates mitosis, migration and epithelial to mesenchymal transition in claudin-low breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-08-01.

Macromolecular crowding tunes 3D collagen architecture and cell morphogenesis

Collagen I is the primary extracellular matrix component of most solid tumors and influences metastatic progression. Collagen matrix engineering techniques are useful for understanding how this complex biomaterial regulates cancer cell behavior and for improving in vitro cancer models. Here, we establish an approach to tune collagen fibril architecture using PEG as an inert molecular crowding agent during gelation and cell embedding. We find that crowding produces matrices with tighter fibril networks that are less susceptible to proteinase mediated degradation, but does not significantly alter matrix stiffness. The resulting matrices have the effect of preventing cell spreading, confining cells, and reducing cell contractility. Matrix degradability and fibril length are identified as strong predictors of cell confinement. Further, the degree of confinement predicts whether breast cancer cells will ultimately undergo individual or collective behaviors. Highly confined breast cancer cells undergo morphogenesis to form either invasive networks reminiscent of aggressive tumors or gland and lobule structures reminiscent of normal breast epithelia. This morphological transition is accompanied by expression of cell-cell adhesion genes, including PECAM1 and ICAM1. Our study suggests that cell confinement, mediated by matrix architecture, is a design feature that tunes the transcriptional and morphogenic state of breast cancer cells.

723. Validation of a Wild-Type Influenza A/Texas-Like H3N2 Human Challenge Model with Comparison to the Validated A(H1N1)pdm09 Model

Background

Healthy volunteer challenge studies provide an opportunity to better understand influenza pathogenesis and correlates of protection. The development of vaccines and therapeutics has relied on these studies as will future universal vaccine candidates. The first fully validated wild-type human infection model with A(H1N1)pdm09 was developed at the NIH Clinical Center (CC) in 2012 and this study represents the first validation of a wild-type seasonal H3N2 human infection model. The objective of this study was to characterize a wild-type Influenza A/Texas-like H3N2 challenge virus in healthy volunteers.

Methods

Healthy volunteers were isolated at the NIH CC for a minimum of 9 days. Subjects received a single dose of a reverse genetics, cell-based, GMP, wild-type A H3N2 virus intranasally. Dose escalation was performed from 104 to 107 TCID50. Viral shedding and clinical disease were evaluated daily, including clinician assessments and a validated patient-reported outcome tool, FLU-PRO©.

Results

A total of 37 subjects were challenged. Sixteen (43%) subjects had viral shedding and 27 (73%) developed influenza symptoms, with 12 subjects (32%) experiencing mild-to-moderate influenza disease (MMID) defined as symptoms and shedding. Only subjects receiving the 106 and 107 TCID50 doses experienced MMID at 44% and 40%, respectively. Nose and throat symptoms were most common and peaked by Days 2–3 post-challenge. Although serum antibody responses were observed, many of these responses were limited in a significant number of subjects.

Conclusion

The A/Texas-like H3N2 Influenza challenge virus safely induced MMID in healthy volunteers, but was less effective than the A(H1N1)pdm09 challenge virus. This lower MMID rate of 40% was observed at the 107 TCID50 dose and was driven by less detection of shedding as the incidence of symptoms was similar to A(H1N1)pdm09. The limited serum antibody responses observed demonstrate that preexisting immunity in healthy volunteers against the seasonal H3N2 lineage may limit shedding compared with the more recently emerged seasonal A(H1N1)pdm09 lineage. The successful characterization of this H3N2 model makes future studies using this model to explore viral pathogenesis or evaluate vaccines possible.

This research was supported by the Intramural Research Program of the NIH, NIAID.

Disclosures

All authors: No reported disclosures.

Using the Influenza Patient-reported Outcome (FLU-PRO) diary to evaluate symptoms of influenza viral infection in a healthy human challenge model

BACKGROUND

In clinical studies involving a healthy volunteer human challenge model, a valid and reliable measure to assess the evolution of patient-reported symptom type and severity following viral exposure is necessary. This study examines the use of the InFLUenza Patient-Reported Outcome (FLU-PRO) diary as a standardized measure of symptom severity in a healthy volunteer human challenge model.

METHODS

Healthy adults admitted to the NIH Clinical Center (Day - 1) underwent a 9-day inpatient quarantine after intranasal challenge with a wild-type influenza A/H1N1pdm virus (Day 0). Participants completed the 32-item FLU-PRO diary twice daily for 14 days to assess presence, severity, and duration of symptoms across six body systems. Secondary analyses included descriptive statistics to examine FLU-PRO scores over the course of illness and analysis of variance to compare scores on Day 3 post-challenge by presence of viral shedding, and pre-challenge hemagglutinin and neuraminidase inhibition (HAI and NAI) titers.

RESULTS

All but one subject (99%), who was lost to follow-up, completed twice daily FLU-PRO diaries on all study assessment days. FLU-PRO demonstrated that 61 of 65 subjects reported symptoms (Days: Median 5, Mean 6 ± 7), of whom 37 (61%) had viral shedding. Pre-challenge, 39 (64%) and 10 (16%) subjects had low (< 1:40) HAI and NAI titers, respectively. Nose, throat, body, and gastrointestinal (GI) symptoms reached peak intensity at Day 3, followed by chest/respiratory and eye symptoms at Day 4. Subjects with viral shedding had higher mean FLU-PRO scores compared to those without, except for Eye and GI domains (p <0.05). Mean FLU-PRO scores were significantly higher for subjects with low NAI titer (p <0.05) across all domains. No significant differences were observed between HAI titer groups. FLU-PRO scores of the low HAI-low NAI group (n = 10) were significantly higher (more severe) than the other two groups (p < 0.05) (high HAI-high NAI (n = 22), low HAI-high NAI (n = 29)).

CONCLUSIONS

The FLU-PRO had high adherence and low respondent burden. It can be used to track symptom onset, intensity, duration, and recovery from influenza infection in clinical research. In this human challenge study, scores were responsive to change and distinguished known clinical subgroups.

TRIAL REGISTRATION

NCT01971255 First Registered October 2, 2013.

Performance of the inFLUenza Patient-Reported Outcome (FLU-PRO) diary in patients with influenza-like illness (ILI)

BACKGROUND

The inFLUenza Patient Reported Outcome (FLU-PRO) measure is a daily diary assessing signs/symptoms of influenza across six body systems: Nose, Throat, Eyes, Chest/Respiratory, Gastrointestinal, Body/Systemic, developed and tested in adults with influenza.

OBJECTIVES

This study tested the reliability, validity, and responsiveness of FLU-PRO scores in adults with influenza-like illness (ILI).

METHODS

Data from the prospective, observational study used to develop and test the FLU-PRO in influenza virus positive patients were analyzed. Adults (≥18 years) presenting with influenza symptoms in outpatient settings in the US, UK, Mexico, and South America were enrolled, tested for influenza virus, and asked to complete the 37-item draft FLU-PRO daily for up to 14-days. Analyses were performed on data from patients testing negative. Reliability of the final, 32-item FLU-PRO was estimated using Cronbach's alpha (α; Day 1) and intraclass correlation coefficients (ICC; 2-day reproducibility). Convergent and known-groups validity were assessed using patient global assessments of influenza severity (PGA). Patient report of return to usual health was used to assess responsiveness (Day 1-7).

RESULTS

The analytical sample included 220 ILI patients (mean age = 39.3, 64.1% female, 88.6% white). Sixty-one (28%) were hospitalized at some point in their illness. Internal consistency reliability (α) of FLU-PRO Total score was 0.90 and ranged from 0.72-0.86 for domain scores. Reproducibility (Day 1-2) was 0.64 for Total, ranging from 0.46-0.78 for domain scores. Day 1 FLU-PRO scores correlated (≥0.30) with the PGA (except Gastrointestinal) and were significantly different across PGA severity groups (Total: F = 81.7, p<0.001; subscales: F = 6.9-62.2; p<0.01). Mean score improvements Day 1-7 were significantly greater in patients reporting return to usual health compared with those who did not (p<0.05, Total and subscales, except Gastrointestinal and Eyes).

CONCLUSIONS

Results suggest FLU-PRO scores are reliable, valid, and responsive in adults with influenza-like illness.

Analysis of Two Quantitative Ultrasound Approaches

There are two well-known ultrasonic approaches to extract sets of quantitative parameters: Lizzi-Feleppa (LF) parameters: slope, intercept, and midband; and quantitative ultrasound (QUS)-derived parameters: effective scatterer diameter (ESD) and effective acoustic concentration (EAC). In this study, the relation between the LF and QUS-derived parameters is studied theoretically and experimentally on ex vivo mouse livers. As expected from the theory, LF slope is correlated to ESD ([Formula: see text]), and from experimental data, LF midband is correlated to EAC ([Formula: see text]). However, LF intercept is not correlated to ESD ([Formula: see text]) nor EAC ([Formula: see text]). The unexpected correlation observed between LF slope and EAC ([Formula: see text]) results likely from the high correlation between ESD and EAC due to the inversion process. For a liver fat percentage estimation, an important potential medical application, the parameters presenting the better correlation are EAC ([Formula: see text]) and LF midband ([Formula: see text]).

Abstract P5-06-01: Proteomic analysis of conserved kinases between PDX tumors and corresponding PDX-derived cell lines

(Background) Patient-derived xenograft (PDX)s are valuable models for precision oncology as they are thought to recapitulate the biological and genomic characteristics of the human tumors they were derived from. Even though this model is widely used, it is still difficult to manipulate genes in this system and it is not as convenient as in vitro cell culture for drug sensitivity screening. On the other hand in vitro cell cultures have a highly artificial microenvironment and also have undergone selection which might generate misleading data. To address these issues cell lines from PDX tumors with different intrinsic subtypes were characterized by kinobead precipitation/mass spectrometry analysis (KiP/MS) to profile each PDX line in vivo and ex vivo for therapeutic targets.

(Materials and Methods)Washington University Human in Mice (WHIM) tumors and Hutsman Cancer Institute (HCI) tumors were transplanted into mammary fat pads of female severe combined immunodeficiency/beige (SCID/beige) mice. PDXs tumors were harvested when they reached 1˜1.5cm. PDX tumor-derived ex vivo cells/organoids were routinely cultured with Rock inhibitor support. Estradiol was applied only for the tumors originating from E2 supplementation in vivo. Cells and tumors were harvested and lysed by sonication. Kinases in soluble lysates are enriched with drug-bound beads (kinobead) and digested with trypsin. Digested peptides are analyzed by mass spectrometry.

(Results) 5 of WHIM tumors and 4 of HCI tumors were successfully dissociated and cultured ex vivo for further analysis and experiments. Hierarchical clustering of tumors and corresponding cells showed ex vivo cultured cells cluster together with their original PDX tumors. Tumors/ex vivo cultured cells clustered by intrinsic subtype and enrichment analysis identified specific kinases for each PDX tumor/cell line. The WHIM 4 tumor-cell pair showed high level of PIM kinase and EGFR and other PDX tumors such as WHIM18, WHIM 20 (Luminal subtypes), WHIM 35(HER2 enriched subtype) also showed model unique intrinsic kinases, such as JAK2 for WHIM18, EPHB4 for WHIM20.

(Conclusion) PDX tumor-derived ex vivo lines could be routinely cultured with Rock inhibitor support. Each PDX tumor and cell line pair were cluster together in hierarchical clustering and categorized into the same intrinsic subtype based on kinome profiling, suggesting these cells maintain their tumor specific intrinsic kinase signaling. A subset of kinases exhibit activity/expression that is conserved after ex vivo culture, we hypothesize these are intrinsic kinases might be promising target for treatment, because they are tumor intrinsic, i.e. their high expression is maintained despite the strong contrast in the microenvironment of in vitro versus in vitro growth. Ongoing studies with drugs and knock down reagents are examining whether the in vivo/ex vivo comparative KIP analysis indeed identifies therapeutic targets, which will be presented at the meeting more in detail.

Citation Format: Han A, Kim B-J, Chan DW, Matsunuma R, Singh P, Ellis MJ. Proteomic analysis of conserved kinases between PDX tumors and corresponding PDX-derived cell lines [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-06-01.

Reliability, Validity, and Responsiveness of InFLUenza Patient-Reported Outcome (FLU-PRO©) Scores in Influenza-Positive Patients

OBJECTIVES

To assess the reliability, validity, and responsiveness of InFLUenza Patient-Reported Outcome (FLU-PRO©) scores for quantifying the presence and severity of influenza symptoms.

METHODS

An observational prospective cohort study of adults (≥18 years) with influenza-like illness in the United States, the United Kingdom, Mexico, and South America was conducted. Participants completed the 37-item draft FLU-PRO daily for up to 14 days. Item-level and factor analyses were used to remove items and determine factor structure. Reliability of the final tool was estimated using Cronbach α and intraclass correlation coefficients (2-day reliability). Convergent and known-groups validity and responsiveness were assessed using global assessments of influenza severity and return to usual health.

RESULTS

Of the 536 patients enrolled, 221 influenza-positive subjects comprised the analytical sample. The mean age of the patients was 40.7 years, 60.2% were women, and 59.7% were white. The final 32-item measure has six factors/domains (nose, throat, eyes, chest/respiratory, gastrointestinal, and body/systemic), with a higher order factor representing symptom severity overall (comparative fit index = 0.92; root mean square error of approximation = 0.06). Cronbach α was high (total = 0.92; domain range = 0.71-0.87); test-retest reliability (intraclass correlation coefficient, day 1-day 2) was 0.83 for total scores and 0.57 to 0.79 for domains. Day 1 FLU-PRO domain and total scores were moderately to highly correlated (≥0.30) with Patient Global Rating of Flu Severity (except nose and throat). Consistent with known-groups validity, scores differentiated severity groups on the basis of global rating (total: F = 57.2, P < 0.001; domains: F = 8.9-67.5, P < 0.001). Subjects reporting return to usual health showed significantly greater (P < 0.05) FLU-PRO score improvement by day 7 than did those who did not, suggesting score responsiveness.

CONCLUSIONS

Results suggest that FLU-PRO scores are reliable, valid, and responsive to change in influenza-positive adults.

3D collagen architecture induces a conserved migratory and transcriptional response linked to vasculogenic mimicry

The topographical organization of collagen within the tumor microenvironment has been implicated in modulating cancer cell migration and independently predicts progression to metastasis. Here, we show that collagen matrices with small pores and short fibers, but not Matrigel, trigger a conserved transcriptional response and subsequent motility switch in cancer cells resulting in the formation of multicellular network structures. The response is not mediated by hypoxia, matrix stiffness, or bulk matrix density, but rather by matrix architecture-induced β1-integrin upregulation. The transcriptional module associated with network formation is enriched for migration and vasculogenesis-associated genes that predict survival in patient data across nine distinct tumor types. Evidence of this gene module at the protein level is found in patient tumor slices displaying a vasculogenic mimicry (VM) phenotype. Our findings link a collagen-induced migration program to VM and suggest that this process may be broadly relevant to metastatic progression in solid human cancers.

Extracellular matrix plays a central role in driving cancer development. Here the authors using an in vitro approach show that confining collagen architectures induce fast and persistent cell migration and the formation of multicellular network structures linked to vascular mimicry observed in tumours from patients.

Comparison of Kaposi Sarcoma Risk in Human Immunodeficiency Virus-Positive Adults Across 5 Continents: A Multiregional Multicohort Study

BACKGROUND

We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America.

METHODS

We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs).

RESULTS

We included 208140 patients from 57 countries. Over a period of 1066572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts ≥700 cells/µL with those whose counts were <50 cells/µL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by ≥95% in other regions.

CONCLUSIONS

Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa.

Impedance spectroscopy-based cell/particle position detection in microfluidic systems

An impedance spectroscopy-based cell/particle position detection method in microfluidic systems is presented. A single pair of non-parallel surface microelectrodes was utilized to detect the transverse positions of particles/cells flowing in a microchannel without the need for a multi-electrode multi-channel impedance detection. This method can be a simple solution for high-throughput and low-cost position detection in microfluidic sorting and separation applications.

Involved-field irradiation in definitive chemoradiotherapy for T4 squamous cell carcinoma of the esophagus

OBJECTIVES

Definitive concurrent chemoradiotherapy (ccrt) is currently a therapeutic option for locally advanced esophageal cancer. However, clinical practice differs with respect to the target volume for irradiation. The purpose of the present study was to analyze failure patterns and survival, and to determine the feasibility of using involved-field irradiation (ifi) with concurrent chemotherapy for T4 squamous cell carcinoma (scc) of the esophagus.

METHODS

Between January 2003 and January 2013, 56 patients with clinical T4M0 scc of the esophagus received ccrt using ifi. The radiation field included the primary tumour and clinically involved lymph nodes. Target volumes and sites of failure were analyzed, as were treatment-related toxicity and survival time.

RESULTS

In this 56-patient cohort, 13 patients (23.2%) achieved a complete response, and 21 (37.5%) achieved a partial response, for a total response rate of 60.7%. The major toxicities experienced were leucocytopenia and esophagitis, with 14 patients (25.0%) experiencing grade 3 toxicities. At a median follow-up of 34 months, 48 patients (85.7%) had experienced failure: 39 (69.6%) in-field, 7 (12.5%) elective nodal, and 19 (33.9%) distant. Only 1 patient (1.8%) experienced isolated elective nodal failure. The 1-, 2-, and 3-year survival rates were 39.3%, 21.4%, and 12.5% respectively.

CONCLUSIONS

For patients with T4M0 scc of the esophagus, definitive ccrt using ifi resulted in an acceptable rate of isolated elective nodal failure and an overall survival comparable to that achieved with elective nodal irradiation. A limited radiation therapy target volume, including only clinically involved lesions, would therefore be a feasible choice for this patient subgroup.

Biased signalling and proteinase-activated receptors (PARs): targeting inflammatory disease

Although it has been known since the 1960s that trypsin and chymotrypsin can mimic hormone action in tissues, it took until the 1990s to discover that serine proteinases can regulate cells by cleaving and activating a unique four-member family of GPCRs known as proteinase-activated receptors (PARs). PAR activation involves the proteolytic exposure of its N-terminal receptor sequence that folds back to function as a 'tethered' receptor-activating ligand (TL). A key N-terminal arginine in each of PARs 1 to 4 has been singled out as a target for cleavage by thrombin (PARs 1, 3 and 4), trypsin (PARs 2 and 4) or other proteases to unmask the TL that activates signalling via Gq , Gi or G12 /13 . Similarly, synthetic receptor-activating peptides, corresponding to the exposed 'TL sequences' (e.g. SFLLRN-, for PAR1 or SLIGRL- for PAR2) can, like proteinase activation, also drive signalling via Gq , Gi and G12 /13 , without requiring receptor cleavage. Recent data show, however, that distinct proteinase-revealed 'non-canonical' PAR tethered-ligand sequences and PAR-activating agonist and antagonist peptide analogues can induce 'biased' PAR signalling, for example, via G12 /13 -MAPKinase instead of Gq -calcium. This overview summarizes implications of this 'biased' signalling by PAR agonists and antagonists for the recognized roles the PARs play in inflammatory settings.