The dynamic response of quorum sensing to density is robust to signal supplementation and individual signal synthase knockouts.

Quorum sensing (QS) is a widespread mechanism of environment sensing and behavioural coordination in bacteria. At its core, QS is based on the production, sensing and response to small signalling molecules. Previous work with Pseudomonas aeruginosa shows that QS can be used to achieve quantitative resolution and deliver a dosed response to the bacteria's density environment, implying a sophisticated mechanism of control. To shed light on how the mechanistic signal components contribute to graded responses to density, we assess the impact of genetic (AHL signal synthase deletion) and/or signal supplementation (exogenous AHL addition) perturbations on lasB reaction-norms to changes in density. Our approach condenses data from 2000 timeseries (over 74 000 individual observations) into a comprehensive view of QS-controlled gene expression across variation in genetic, environmental and signal determinants of lasB expression. We first confirm that deleting either (∆lasI, ∆rhlI) or both (∆lasIrhlI) AHL signal synthase gene attenuates QS response to density. In the ∆rhlI background we show persistent yet attenuated density-dependent lasB expression due to native 3-oxo-C12-HSL signalling. We then test if density-independent quantities of AHL signal (3-oxo-C12-HSL, C4-HSL) added to the WT either flatten or increase responsiveness to density and find that the WT response is robust to all tested concentrations of signal, alone or in combination. We then move to progressively supplementing the genetic knockouts and find that cognate signal supplementation of a single AHL signal (∆lasI +3-oxo-C12-HSL, ∆rhlI +C4HSL) is sufficient to restore the ability to respond in a density-dependent manner to increasing density. We also find that dual signal supplementation of the double AHL synthase knockout restores the ability to produce a graded response to increasing density, despite adding a density-independent amount of signal. Only the addition of high concentrations of both AHLs and PQS can force maximal lasB expression and ablate responsiveness to density. Our results show that density-dependent control of lasB expression is robust to multiple combinations of QS gene deletion and density-independent signal supplementation. Our work develops a modular approach to query the robustness and mechanistic bases of the central environmental sensing phenotype of quorum sensing.

Challenges and opportunities for cheat therapy in the control of bacterial infections.

Covering: 1999 to 2021Bacterial pathogens can be highly social, communicating and cooperating within multi-cellular groups to make us sick. The requirement for collective action in pathogens presents novel therapeutic avenues that seek to undermine cooperative behavior, what we call here 'cheat therapies'. We review two broad avenues of cheat therapy: first, the introduction of genetically engineered 'cheat' strains (bio-control cheats), and second the chemical induction of 'cheat' behavior in the infecting pathogens (chemical-control cheats). Both genetically engineered and chemically induced cheats can socially exploit the cooperative wildtype infection, reducing pathogen burden and the severity of disease. We review the costs and benefits of cheat therapies, highlighting advantages of evolutionary robustness and also the challenges of low to moderate efficacy, compared to conventional antibiotic treatments. We end with a summary of what we see as the most valuable next steps, focusing on adjuvant treatments and use as alternate therapies for mild, self-resolving infections - allowing the reservation of current and highly effective antibiotics for more critical patient needs.

Combinatorial quorum sensing in Pseudomonas aeruginosa allows for novel cheating strategies.

In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) is a social trait that is exploitable by non-cooperating cheats. Previously it has been shown that by linking QS to the production of both public and private goods, cheats can be prevented from invading populations of cooperators and this was described by Dandekar et al. (Science 2012;338:264-266) as 'a metabolic incentive to cooperate'. We hypothesized that P. aeruginosa could evolve novel cheating strategies to circumvent private goods metabolism by rewiring its combinatorial response to two QS signals (3O-C12-HSL and C4-HSL). We performed a selection experiment that cycled P. aeruginosa between public and private goods growth media and evolved an isolate that rewired its control of cooperative protease expression from a synergistic (AND-gate) response to dual-signal input to a 3O-C12-HSL-only response. We show that this isolate circumvents metabolic incentives to cooperate and acts as a combinatorial signalling cheat, with higher fitness in competition with its ancestor. Our results show three important principles: first, combinatorial QS allows for diverse social strategies to emerge; second, restrictions levied by private goods are not sufficient to explain the maintenance of cooperation in natural populations; and third, modifying combinatorial QS responses could result in important physiological outcomes in bacterial populations.

Patient-reported outcomes in sickle cell disease and association with clinical and psychosocial factors: Report from the sickle cell disease implementation consortium.

Understanding patient experiences, quality of life, and treatment needs in individuals with sickle cell disease (SCD) is essential in promoting health and well-being. We used measures from the Adult Sickle Cell Quality of Life Measurement Information System (ASCQ-Me), Patient Reported Outcomes Measurement Information System (PROMIS), and Quality of Life in Neurological Disorders (NeuroQol) to evaluate pain impact, sleep impact, social functioning, depressive symptoms, tiredness, and cognitive function (collectively, patient reported outcomes [PROs]) and to identify associated demographic and clinical characteristics. Participants (n = 2201) between 18 and 45 years were recruited through the eight Sickle Cell Disease Implementation Consortium (SCDIC) sites. In multivariate models, PROs were significantly associated with one another. Pain impact was associated with age, education, employment, time since last pain attack, hydroxyurea use, opioid use, sleep impact, social functioning, and cognitive function (F = 88.74, P < .0001). Sleep impact was associated with household income, opioid use, pain impact, social functioning, depressive symptoms, and tiredness (F = 101.40, P < .0001). Social functioning was associated with employment, pain attacks in the past year, autoimmune/inflammatory comorbidities, pain impact, sleep impact, depressive symptoms, tiredness, and cognitive function (F = 121.73, P < .0001). Depressive symptoms were associated with sex, sleep impact, social functioning, tiredness, and cognitive function (F = 239.51, P < .0001). Tiredness was associated with sex, education, sleep impact, social functioning, depressive symptoms, and cognitive function (F = 129.13, P < .0001). These findings reflect the baseline PRO assessments among SCDIC registry participants. Further research is needed to better understand these outcomes and new targets for interventions to improve quality of life and function in people with SCD.

Antibiotic stress selects against cooperation in the pathogenic bacterium Pseudomonas aeruginosa.

Cheats are a pervasive threat to public goods production in natural and human communities, as they benefit from the commons without contributing to it. Although ecological antagonisms such as predation, parasitism, competition, and abiotic environmental stress play key roles in shaping population biology, it is unknown how such stresses generally affect the ability of cheats to undermine cooperation. We used theory and experiments to address this question in the pathogenic bacterium, Pseudomonas aeruginosa Although public goods producers were selected against in all populations, our competition experiments showed that antibiotics significantly increased the advantage of nonproducers. Moreover, the dominance of nonproducers in mixed cultures was associated with higher resistance to antibiotics than in either monoculture. Mathematical modeling indicates that accentuated costs to producer phenotypes underlie the observed patterns. Mathematical analysis further shows how these patterns should generalize to other taxa with public goods behaviors. Our findings suggest that explaining the maintenance of cooperative public goods behaviors in certain natural systems will be more challenging than previously thought. Our results also have specific implications for the control of pathogenic bacteria using antibiotics and for understanding natural bacterial ecosystems, where subinhibitory concentrations of antimicrobials frequently occur.

Behavioral symptoms and psychiatric disorders in child and adolescent long-term survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only.

BACKGROUND: Prevalence of emotional, behavioral, and psychiatric outcomes in child and adolescent survivors of childhood acute lymphoblastic leukemia treated on a chemotherapy-only protocol were not well defined. METHODS: Self- and parent-reported emotional and behavioral symptoms were assessed for 161 survivors of childhood acute lymphoblastic leukemia (51.0% female; mean [SD] age 12.1[2.6] years; 7.5[1.6] years post-diagnosis). Age- and sex-adjusted scores were calculated for standardized measures and compared with 90th percentile of norms. Frequencies of survivor psychiatric disorders from structured diagnostic interviews with parents were compared with the general population. Parent emotional distress and post-traumatic stress symptoms were assessed. Associations between child symptoms/disorders and parent distress were examined with log-binomial models, adjusting for highest parent education. RESULTS: Compared with population expectations (10%), more survivors self-reported symptoms of inattention (27.9; 95% CI, 21.0%-35.7%), hyperactivity/impulsivity (26.0%; CI, 19.2%-33.6%), and oppositional-defiant behavior (20.1%; CI, 14.1%-27.3%). Parents reported survivors with more symptoms of inattention (23.6%; CI, 17.2%-31.0%), higher frequencies of obsessive-compulsive disorder (10.3% vs 2%) and oppositional defiant disorder (16.0% vs 9.5%), but not attention-deficit/hyperactivity disorder (7.1% vs 7.8%) or generalized anxiety disorder (3.2% vs 4.1%), compared with national norms. Parent-report of child anxiety disorders was associated with parent self-reported emotional distress but not survivor self-report of anxiety. CONCLUSION: A significant minority of survivors have long-term psychiatric morbidity, multi-informant assessment is important to understand these symptom profiles and to inform selection of appropriate interventions. Interventions targeting inattention and oppositional behavior in children and emotional distress in parents are warranted in families with survivors who display behavioral problems.

Sickle Cell Clinical Research and Intervention Program (SCCRIP): A lifespan cohort study for sickle cell disease progression from the pediatric stage into adulthood.

BACKGROUND: Previous natural history studies have advanced the understanding of sickle cell disease (SCD), but generally have not included sufficient lifespan data or investigation of the role of genetics in clinical outcomes, and have often occurred before the widespread use of disease-modifying therapies, such as hydroxyurea and chronic erythrocyte transfusions. To further advance knowledge of SCD, St. Jude Children's Research Hospital established the Sickle Cell Clinical Research and Intervention Program (SCCRIP), to conduct research in a clinically evaluated cohort of individuals with SCD across their lifetime. PROCEDURES: Initiated in 2014, the SCCRIP study prospectively recruits patients diagnosed with SCD and includes retrospective and longitudinal collection of clinical, neurocognitive, geospatial, psychosocial, and health outcomes data. Biological samples are banked for future genomics and proteomics studies. The organizational structure of SCCRIP is based upon organ/system-specific working groups and is opened to the research community for partnerships. RESULTS: As of August 2017, 1,044 (92.3% of eligible) patients with SCD have enrolled in the study (860 children and 184 adults), with 11,915 person-years of observation. Population demographics included mean age at last visit of 11.3 years (range 0.7-30.1), 49.8% females, 57.7% treated with hydroxyurea, 8.5% treated with monthly transfusions, and 62.9% hemoglobin (Hb) SS or HbSB0 -thalassemia, 25.7% HbSC, 8.4% HbsB+ -Thalassemia, 1.7% HbS/HPFH, and 1.2% other. CONCLUSIONS: The SCCRIP cohort will provide a rich resource for the conduct of high impact multidisciplinary research in SCD.

Factors associated with residential mobility during pregnancy.

Our objective was to determine the factors associated with residential moving during pregnancy, as it may increase stress during pregnancy and affect birth outcomes. Data were obtained from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study. Participants were recruited from December 2006 to June 2011 and included 1,448 pregnant women. The average gestational age at enrollment was 23 weeks. The primary outcome of residential mobility was defined as any change in address during pregnancy. Multivariate regression was used to assess the adjusted associations of factors with residential mobility. Out of 1,448 participants, approximately 9 percent moved between baseline (enrollment) and delivery. After adjusting for covariates, mothers with lower educational attainment [less than high school (adjusted odds ratio [aOR] = 3.74, 95% confidence interval [CI] = 1.78, 7.85) and high school/technical school (aOR = 3.57, 95% CI = 2.01, 6.32) compared to college degree or higher], and shorter length of residence in neighborhood were more likely to have moved compared to other mothers. Length of residence was protective of mobility (aOR = 0.91, 95% CI = 0.86, 0.96 per year). Increased understanding of residential mobility during pregnancy may help improve the health of mothers and their children.

Network structure and local adaptation in co-evolving bacteria-phage interactions.

Numerous theoretical and experimental studies have investigated antagonistic co-evolution between parasites and their hosts. Although experimental tests of theory from a range of biological systems are largely concordant regarding the influence of several driving processes, we know little as to how mechanisms acting at the smallest scales (individual molecular and phenotypic changes) may result in the emergence of structures at larger scales, such as co-evolutionary dynamics and local adaptation. We capitalized on methods commonly employed in community ecology to quantify how the structure of community interaction matrices, so-called bipartite networks, reflected observed co-evolutionary dynamics, and how phages from these communities may or may not have adapted locally to their bacterial hosts. We found a consistent nested network structure for two phage types, one previously demonstrated to exhibit arms race co-evolutionary dynamics and the other fluctuating co-evolutionary dynamics. Both phages increased their host ranges through evolutionary time, but we found no evidence for a trade-off with impact on bacteria. Finally, only bacteria from the arms race phage showed local adaptation, and we provide preliminary evidence that these bacteria underwent (sometimes different) molecular changes in the wzy gene associated with the LPS receptor, while bacteria co-evolving with the fluctuating selection phage did not show local adaptation and had partial deletions of the pilF gene associated with type IV pili. We conclude that the structure of phage-bacteria interaction networks is not necessarily specific to co-evolutionary dynamics, and discuss hypotheses for why only one of the two phages was, nevertheless, locally adapted.

Combinatorial quorum sensing allows bacteria to resolve their social and physical environment.

Quorum sensing (QS) is a cell-cell communication system that controls gene expression in many bacterial species, mediated by diffusible signal molecules. Although the intracellular regulatory mechanisms of QS are often well-understood, the functional roles of QS remain controversial. In particular, the use of multiple signals by many bacterial species poses a serious challenge to current functional theories. Here, we address this challenge by showing that bacteria can use multiple QS signals to infer both their social (density) and physical (mass-transfer) environment. Analytical and evolutionary simulation models show that the detection of, and response to, complex social/physical contrasts requires multiple signals with distinct half-lives and combinatorial (nonadditive) responses to signal concentrations. We test these predictions using the opportunistic pathogen Pseudomonas aeruginosa and demonstrate significant differences in signal decay between its two primary signal molecules, as well as diverse combinatorial responses to dual-signal inputs. QS is associated with the control of secreted factors, and we show that secretome genes are preferentially controlled by synergistic "AND-gate" responses to multiple signal inputs, ensuring the effective expression of secreted factors in high-density and low mass-transfer environments. Our results support a new functional hypothesis for the use of multiple signals and, more generally, show that bacteria are capable of combinatorial communication.

Birth Prevalence of Sickle Cell Trait and Sickle Cell Disease in Shelby County, TN.

BACKGROUND: Accurate quantification of the regional burden of sickle cell disease (SCD) is vital to allocating health-related resources. Shelby County, TN, which includes the city of Memphis and the regional pediatric SCD treatment center at St. Jude Children's Research Hospital, is home to a large population of African Americans. PROCEDURE: We postulated that the regional birth prevalence of SCD in Shelby County, TN, would differ from national rates. Using data from 2002 to 2012, we estimated the birth prevalence of SCD and sickle cell trait (SCT) in Shelby County and evaluated the distribution of SCD cases by ZIP code of residence with geographic information systems (GIS). RESULTS: The prevalence of SCD in African Americans was 1/287 (95% confidence interval [CI]: 1/323, 1/256) live births, significantly higher than the nationally reported 1/350 -1/500. The prevalence of SCT in African Americans was 1/14.7 (95% CI: 1/15.0, 1/14.3) live births, significantly lower than the nationally reported 1/12. We found that 48% of the SCD cases resided in only six of the 37 residential ZIP codes, and using GIS mapping there were two clusters composed of two and four adjacent urban ZIP codes. SCT cases were also centered predominantly in the same two clusters, but slightly more dispersed. CONCLUSIONS: Recent Shelby County birth prevalence estimates differ substantially from national estimates with higher SCD and lower SCT than expected. Preliminary evidence suggests substantial clustering in two small geographic urban areas within Shelby County that may provide target areas for educational and outreach services.

Distance from an Urban Sickle Cell Center and its Effects on Routine Healthcare Management and Rates of Hospitalization.

The St. Jude Children's Research Hospital (St. Jude) comprehensive sickle cell center serves a 150 mile catchment radius around Memphis, TN, USA. Full travel expenses are provided for routine and acute care visits for sickle cell disease patients living 35 miles from St. Jude. We compared hospitalization rates to national estimates and assessed if driving distance was a barrier to sickle cell healthcare despite the travel reimbursement policy. We evaluated the associations between hospitalizations and routine clinic visits and distance from St. Jude using negative binomial models and we conducted bias analyses by Monte Carlo simulation. We followed 545 patients (2550 patient-years) aged 18 years with sickle cell disease (Hb SS only) from 2007 to 2012. The hospitalization rate per patient-year was 0.65 [95% CI (confidence interval): 0.62, 0.68), significantly lower than the national rate of 1.16 (95% CI: 1.14, 1.18). Children living 5 35 miles from St. Jude had 1.75 (95% CI: 1.41, 2.17) times the rate of hospitalization and 1.22 (95% CI: 1.07, 1.39) times the rate of clinic visits compared to those 35 miles. Bias analysis suggested that under-reporting could explain the observed difference in hospitalization rates if 30.0% of patients who lived 35 miles from the hospital under-reported six hospitalizations over 6 years. The hospitalization rate at St. Jude in children with sickle cell disease was lower than expected from national rates. Greater distance from the sickle cell center (4 35 miles) was associated with decreased hospitalization rates, despite the travel allowances that are provided for those who live 35 miles from the hospital.

Genetic and clinical factors associated with obesity among adult survivors of childhood cancer: A report from the St. Jude Lifetime Cohort.

BACKGROUND: The objective of this study was to identify treatment and genetic factors associated with obesity among childhood cancer survivors. METHODS: Participants included 1996 survivors who previously received treatment for cancer at St. Jude Children's Research Hospital and who survived ≥10 years from diagnosis (median age at diagnosis, 7.2 years; median age at follow-up, 32.4 years). Obesity was defined as a body mass index ≥30 kg/m(2) . The factors associated with adult obesity were identified by subgroup-specific (cranial radiation [CRT] exposure status) multivariable logistic regression. Single nucleotide polymorphisms (SNPs) associated with obesity were identified by subgroup-specific, exploratory, genome-wide association analyses using a 2-stage resampling approach with a type I error rate of 5 × 10(-6) . RESULTS: Forty-seven percent of survivors who received CRT and 29.4% of those who did not receive CRT were obese at evaluation. In multivariable analyses, abdominal/pelvic radiation exposure was associated with decreased prevalence of obesity among survivors regardless of CRT status (P < .0001). The odds of obesity were increased among survivors who received CRT who had also received glucocorticoids (P = .014) or who were younger at diagnosis (P = .013). Among the survivors who had received CRT, 166 SNPs were associated with obesity. The strongest association was observed with reference SNP rs35669975 (P = 3.3 × 10(-8) ) on segment 33.3 of the long arm of chromosome 13 (13q33.3), approximately 30 kb downstream of FAM155A (family with sequence similarity 155, member A). SNPs within the glycine receptor α3 (GLRA3) gene and near the sex-determining region Y box 11 (SOX11) and cadherin 18 type 2 (CDH18) genes also were identified. These genes have been implicated in neural growth, repair, and connectivity. CONCLUSIONS: Obesity in childhood cancer survivors remains associated with previous exposure to CRT and glucocorticoids. Genetic variants related to neural connectivity may modify the risk of obesity among survivors who receive CRT. Validation of these findings in independent cohorts is required.

Treatment-induced hearing loss and adult social outcomes in survivors of childhood CNS and non-CNS solid tumors: Results from the St. Jude Lifetime Cohort Study.

BACKGROUND: Survivors of childhood cancer who are treated with platinum-based chemotherapy and/or cranial radiation are at risk of treatment-induced hearing loss. However, the effects of such hearing loss on adult social attainment have not been well elucidated. METHODS: Adult survivors of pediatric central nervous system (CNS) solid tumors (180 survivors) and non-CNS solid tumors (226 survivors) who were treated with potentially ototoxic cancer therapy completed audiologic evaluations and questionnaires assessing their perception of social functioning and social attainment (ie, independent living, marriage, and employment). Audiograms were graded with the Chang ototoxicity grading scale. Analyses were stratified by tumor type (ie, CNS vs non-CNS). Multivariable logistic regression models were conducted with adjustment for age; sex; chronic health conditions; and, for the CNS group, IQ. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were reported. RESULTS: Serious hearing loss (that requiring a hearing aid or deafness) was detected in 36% of survivors of CNS tumors and 39% of survivors of non-CNS tumors. Serious hearing loss was associated with an increased risk of perceived negative impact in ≥1 areas of social functioning (survivors of non-CNS tumors: OR, 1.83 [95% CI, 1.00-3.34]). Among survivors of non-CNS tumors, serious hearing loss was associated with 2-fold increased risk of nonindependent living (OR, 2.19; 95% CI, 1.19-4.04) and unemployment or not graduating from high school (OR, 1.85; 95% CI, 1.00-3.34). CONCLUSIONS: A substantial proportion of adult survivors of childhood cancer treated with potentially ototoxic therapy have serious hearing loss. Treatment-induced hearing loss was found to be associated with reduced social attainment, both perceived and actual, in this study sample.

Younger age distribution of cervical cancer incidence among survivors of pediatric and young adult cancers.

BACKGROUND: Pediatric and young adult (PAYA) cancer survivors may have an earlier onset of chronic diseases compared with the general population. We compared the age at cervical cancer diagnosis between PAYA cancer survivors and females in the general US population. METHODS: We used longitudinal data from 9 population-based registries of the Surveillance, Epidemiology, and End Results program collected between 1973 and 2010. PAYA cancer survivors were females diagnosed with any cancer before age 30 years, survived at least 5 years post-diagnosis, and were subsequently diagnosed with invasive cervical cancer (n=46). The general US population comprised females who were diagnosed with invasive cervical cancer as the primary malignancy (n=26,956). We estimated the difference in median age at diagnosis (ß50) and bootstrap 95% confidence limits (CL) of invasive cervical cancer after adjustment for year of diagnosis and race. RESULTS: The median age at diagnosis of invasive cervical cancer was 33 years for female PAYA cancer survivors and 40 years for females in the general US population (ß50=-7.0, 95% CL: -11, -3.2). Similar differences were observed across subgroups of stage and histologic subtype of invasive cervical cancer. CONCLUSION: Our results suggest that PAYA cancer survivors are diagnosed with invasive cervical cancer at a substantially younger age compared with females without a prior cancer diagnosis in the general US population. This issue warrants further study, and could have implications for determining age at initiation or frequency of cervical cancer screening if younger age at diagnosis is attributable to an underlying biological phenomenon.

Predictors of future health-related quality of life in survivors of adolescent cancer.

The purpose of this study was to identify characteristics associated with health-related quality of life (HRQOL) among long-term survivors of adolescent cancer enrolled in the Childhood Cancer Survivor Study. Thirty percent of survivors reported poor physical and/or mental HRQOL. Race/ethnicity, education, and head/neck disfigurement were significantly associated with poor mental HRQOL, while sex, age, household income, obesity, alkylating agents, pelvic radiation, head/neck or limb disfigurement, and walking with a limp were associated with poor physical HRQOL. Identification of high-risk adolescent cancer patients may facilitate timely intervention to attempt to minimize the impact of cancer and treatment on subsequent quality of life.

Time to disease progression in children with relapsed or refractory neuroblastoma treated with ABT-751: a report from the Children's Oncology Group (ANBL0621).

BACKGROUND: ABT-751, an orally bioavailable sulfonamide binds the colchicine site of beta-tubulin and inhibits microtubule polymerization. Prior phase I studies established the recommended dose in children with solid tumors as 200 mg/m(2) PO daily × 7 days every 21 days and subjects with neuroblastoma experienced prolonged stable disease. We conducted a phase 2 study (NCT00436852) in children and adolescents with progressive neuroblastoma to determine if ABT-751 prolonged the time to progression (TTP) compared to a hypothesized standard based on a historical control population. PROCEDURE: Children and adolescents (n = 91) with a median (range) age 7.7 (2.3-21.5) years and progressive neuroblastoma were enrolled and stratified by disease status into disease measureable by CT/MRI (n = 47) or disease assessable by (123) I-metaiodobenzylguanine scintigraphy (MIBG, n = 44). Response was evaluated using RECIST for measureable disease and the Curie score for MIBG-avid disease. RESULTS: ABT-751 was well tolerated. The objective response rate was 7%. The median TTP was 42 days (95% CI: 36, 56) in the measureable disease stratum and 45 days (95% CI: 42, 85) in the MIBG-avid disease stratum. TTP was similar to the historical control group (n = 136, median TTP 42 days). For the combined strata (n = 91), 1-year progression free survival (PFS) was 13 ± 4% and overall survival (OS) was 48 ± 5%. CONCLUSIONS: The low objective response rate and failure to prolong TTP indicate that ABT-751 is not sufficiently active to warrant further development for neuroblastoma. However, this trial demonstrates the utility of TTP as the primary endpoint in phase 2 trials in children and adolescents with neuroblastoma.

Concordance between the chang and the International Society of Pediatric Oncology (SIOP) ototoxicity grading scales in patients treated with cisplatin for medulloblastoma.

BACKGROUND: Reporting ototoxicity is frequently complicated by use of various ototoxicity criteria. The International Society of Pediatric Oncology (SIOP) ototoxicity grading scale was recently proposed for standardized use in reporting hearing loss outcomes across institutions. The aim of this study was to evaluate the concordance between the Chang and SIOP ototoxicity grading scales. Differences between the two scales were identified and the implications these differences may have in the clinical setting were discussed. PROCEDURES: Audiological evaluations were reviewed for 379 patients with newly diagnosed medulloblastoma (ages 3-21 years). Each patient was enrolled on one of two St. Jude clinical protocols that included craniospinal radiation therapy and four courses of 75 mg/m(2) cisplatin chemotherapy. The latest audiogram conducted 5.5-24.5 months post-protocol treatment initiation was graded using the Chang and SIOP ototoxicity criteria. Clinically significant hearing loss was defined as Chang grade ≥2a and SIOP ≥2. Hearing loss was considered serious (requiring a hearing aid) at the level of Chang grade ≥2b and SIOP ≥3. RESULTS: A strong concordance was observed between the Chang and SIOP ototoxicity scales (Stuart's tau-c statistic = 0.89, 95% CI: 0.86, 0.91). Among those patients diagnosed with serious hearing loss, the two scales were in good agreement. However, the scales deviated from one another in classifying patients with less serious or no hearing loss. CONCLUSIONS: Although discrepancies between the Chang and SIOP ototoxicity scales exist primarily for patients with no or minimal hearing loss, the scales share a strong concordance overall.

Assessment of potential bias from non-participation in a dynamic clinical cohort of long-term childhood cancer survivors: results from the St. Jude Lifetime Cohort Study.

BACKGROUND: To evaluate long-term health outcomes among childhood cancer survivors, St. Jude Children's Research Hospital (SJCRH) has established the St. Jude Lifetime Cohort Study (SJLIFE), comprised of adult survivors who undergo risk-directed clinical assessments. As in any human research study, SJLIFE participants are volunteers who may not represent the source population from which they were recruited. A lack of proportional representation could result in biased estimates of exposure-outcome associations. We compared available demographic, disease, and neighborhood level characteristics between participants and the source population to assess the potential for selection bias. PROCEDURES: Potentially eligible patients for SJLIFE were enumerated as of October 31, 2011. Data from electronic medical records were combined with geocoded census data to develop an analytic data set of 3,108 patients (the evaluable source population) of whom 1,766 (57%) underwent clinical assessment (participants). The ratio of relative frequencies (RRFs) for characteristics was compared between participants and the source population, where RRF = 1.0 indicates equal frequency of the characteristic. RESULTS: Participants and the source population had similar frequencies for most characteristics. Characteristics with modest relative differences (RRFs between 0.86 and 1.11) included sex, distance from SJCRH, primary diagnosis, median household income, median home value, and urbanicity. CONCLUSIONS: Our results indicate a lack of substantive differences in the relative frequencies of demographic, disease, or neighborhood characteristics between participants and the source population in SJLIFE, thus alleviating serious concerns about selective non-participation in this cohort. Bias in specific exposure-outcome relations is still possible and will be considered in individual analyses.