ECFS standards of care on CFTR-related disorders: Towards a comprehensive program for affected individuals

After three publications defining an updated guidance on the diagnostic criteria for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (pwCFTR-RDs), establishing its relationship to CFTR-dysfunction and describing the individual disorders, this fourth and last paper in the series addresses some critical challenges facing health care providers and pwCFTR-RD. Topics included are: 1) benefits and obstacles to collect data from pwCFTR-RD are discussed, together with the opportunity to integrate them into established CF-registries; 2) the potential of infants designated CRMS/CFSPID to develop a CFTR-RD and how to communicate this information; 3) a description of the challenges in genetic counseling, with particular regard to phenotypic variability, unknown long-term evolution, CFTR testing and pregnancy termination 4) a proposal for the assessment of potential barriers to the implementation and dissemination of the produced documents to health care professionals involved in the care of pwCFTR-RD and a process to monitor the implementation of the CFTR-RD recommendations; 5) clinical trials investigating the efficacy of CFTR modulators in CFTR-RD and how endpoints and outcomes might be adapted to the heterogeneity of these disorders.

Clinical and functional efficacy of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis carrying the N1303K mutation

BACKGROUND

Elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) significantly improves health outcomes in people with cystic fibrosis (pwCF) carrying one or two F508del mutations. According to in vitro assays performed in FRT cells, 178 additional mutations respond to ELX/TEZ/IVA. The N1303K mutation is not included in this list of mutations. Recent in vitro data suggested that ELX/TEZ/IVA increases N1303K-CFTR activity. Based on the in vitro response, eight patients commenced treatment with ELX/TEZ/IVA.

METHODS

Two homozygotes; and six compound heterozygotes N1303K/nonsense or frameshift mutation pwCF were treated off label with ELX/TEZ/IVA. Clinical data before and 8 weeks after starting treatment were prospectively collected. The response to ELX/TEZ/IVA was assessed in intestinal organoids derived from 5 study patients and an additional patient carrying N1303K that is not receiving treatment.

RESULTS

Compared to the values before commencing treatment, mean forced expiratory volume in 1 second increased by 18.4 percentage points and 26.5% relative to baseline, mean BMI increased by 0.79 Kg/m2, and mean lung clearance index decreased by 3.6 points and 22.2%. There was no significant change in sweat chloride. Nasal potential difference normalized in four patients and remained abnormal in three. Results in 3D intestinal organoids and 2D nasal epithelial cultures showed a response in CFTR channel activity.

CONCLUSIONS

This report supports the previously reported in vitro data, performed in human nasal and bronchial epithelial cells and intestinal organoids, that pwCF who carry the N1303K mutation have a significant clinical benefit by ELX/TEZ/IVA treatment.

Pediatric Drug-Associated Pancreatitis Reveals Concomitant Risk Factors and Poor Reliability of Causality Scoring: Report From INSPPIRE

OBJECTIVES

Drug-associated acute pancreatitis (DAP) studies typically focus on single acute pancreatitis (AP) cases. We aimed to analyze the (1) characteristics, (2) co-risk factors, and (3) reliability of the Naranjo scoring system for DAP using INSPPIRE-2 (the INternational Study group of Pediatric Pancreatitis: In search for a cuRE-2) cohort study of acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) in children.

METHODS

Data were obtained from ARP group with ≥1 episode of DAP and CP group with medication exposure ± DAP. Physicians could report multiple risk factors. Pancreatitis associated with Medication (Med) (ARP+CP) was compared to Non-Medication cases, and ARP-Med vs CP-Med groups. Naranjo score was calculated for each DAP episode.

RESULTS

Of 726 children, 392 had ARP and 334 had CP; 51 children (39 ARP and 12 CP) had ≥1 AP associated with a medication; 61% had ≥1 AP without concurrent medication exposure. The Med group had other risk factors present (where tested): 10 of 35 (28.6%) genetic, 1 of 48 (2.1%) autoimmune pancreatitis, 13 of 51 (25.5%) immune-mediated conditions, 11 of 50 (22.0%) obstructive/anatomic, and 28 of 51 (54.9%) systemic risk factors. In Med group, 24 of 51 (47%) had involvement of >1 medication, simultaneously or over different AP episodes. There were 20 ARP and 4 CP cases in "probable" category and 19 ARP and 7 CP in "possible" category by Naranjo scores.

CONCLUSIONS

Medications were involved in 51 of 726 (7%) of ARP or CP patients in INSPPIRE-2 cohort; other pancreatitis risk factors were present in most, suggesting a potential additive role of different risks. The Naranjo scoring system failed to identify any cases as "definitive," raising questions about its reliability for DAP.

Weight increase in people with cystic fibrosis on CFTR modulator therapy is mainly due to increase in fat mass

Background: Ivacaftor, the first CFTR modulator drug, leads to significant long-term improvement in lung function and weight gain. The mechanism as well as the long-term impact of ivacaftor on weight, resting energy expenditure (REE) and body composition remains to be explored. Methods: This prospective observational study included 18 people with CF (pwCF) (age: median (range) 20 (6-58) years) carrying at least one CFTR gating mutation commencing ivacaftor. Assessments of body composition, REE and laboratory investigations were performed at baseline and 6, 12 and 24 months after treatment initiation. Results: Treatment with ivacaftor was associated with a significantly positive change in BMI z-score at 24 months. Fat mass (mean (95% CL) of 6.5 kg (4.0; 9.0) from baseline, p = 0.0001), but not fat-free mass changed under ivacaftor treatment. There was a significant positive correlation between weight and fat mass change. Overall, there was no significant change in measured REE from baseline (mean (95% CL) of 108 kcal/d (-12; 228), p = 0.07) in our cohort. Pancreatic function and other nutritional markers did not change with treatment, with the exception of an increase in serum vitamin A levels (p = 0.006). Conclusion: The weight gain observed in ivacaftor treated pwCF is predominantly secondary to increases in fat mass warranting early counseling of people starting on CFTR-modulating treatment with respect to healthy diet and physical exercise.

Validating organoid-derived human intestinal monolayers for personalized therapy in cystic fibrosis

Highly effective drugs modulating the defective protein encoded by the CFTR gene have revolutionized cystic fibrosis (CF) therapy. Preclinical drug-testing on human nasal epithelial (HNE) cell cultures and 3-dimensional human intestinal organoids (3D HIO) are used to address patient-specific variation in drug response and to optimize individual treatment for people with CF. This study is the first to report comparable CFTR functional responses to CFTR modulator treatment among patients with different classes of CFTR gene variants using the three methods of 2D HIO, 3D HIO, and HNE. Furthermore, 2D HIO showed good correlation to clinical outcome markers. A larger measurable CFTR functional range and access to the apical membrane were identified as advantages of 2D HIO over HNE and 3D HIO, respectively. Our study thus expands the utility of 2D intestinal monolayers as a preclinical drug testing tool for CF.

Correlation of Electrophysiological and Fluorescence-Based Measurements of Modulator Efficacy in Nasal Epithelial Cultures Derived from People with Cystic Fibrosis

It has been suggested that in vitro studies of the rescue effect of CFTR modulator drugs in nasal epithelial cultures derived from people with cystic fibrosis have the potential to predict clinical responses to the same drugs. Hence, there is an interest in evaluating different methods for measuring in vitro modulator responses in patient-derived nasal cultures. Commonly, the functional response to CFTR modulator combinations in these cultures is assessed by bioelectric measurements, using the Ussing chamber. While this method is highly informative, it is time-consuming. A fluorescence-based, multi-transwell method for assaying regulated apical chloride conductance (Fl-ACC) promises to provide a complementary approach to theratyping in patient-derived nasal cultures. In the present work, we compared Ussing chamber measurements and fluorescence-based measurements of CFTR-mediated apical conductance in matching, fully differentiated nasal cultures derived from CF patients, homozygous for F508del (n = 31) or W1282X (n = 3), or heterozygous for Class III mutations G551D or G178R (n = 5). These cultures were obtained through a bioresource called the Cystic Fibrosis Canada-Sick Kids Program in Individual CF Therapy (CFIT). We found that the Fl-ACC method was effective in detecting positive responses to interventions for all genotypes. There was a correlation between patient-specific drug responses measured in cultures harbouring F508del, as measured using the Ussing chamber technique and the fluorescence-based assay (Fl-ACC). Finally, the fluorescence-based assay has the potential for greater sensitivity for detecting responses to pharmacological rescue strategies targeting W1282X.

β-adrenergic sweat test in children with inconclusive cystic fibrosis diagnosis: Do we need new reference ranges?

BACKGROUND

Investigating inconclusive cystic fibrosis (CF) diagnosis in children is difficult without advanced cystic fibrosis transmembrane conductance regulator (CFTR) function tests. This study investigated the utility of beta (β)-adrenergic sweat test to exclude CF in participants with inconclusive diagnosis (CF suspects) in South Africa.

METHODS

β-adrenergic sweat test and sweat chloride tests (SCT) were performed simultaneously in CF suspects and adult controls (healthy, CFTR heterozygotes and CF). Cholinergic and β-adrenergic induced sweat rate was measured by evaporimetry (transepithelial water loss [TEWL]: g H₂ O/m² /h) following intradermal injections. Next-generation sequencing of CFTR was performed in CF suspects. CF diagnosis was defined by genotype.

RESULTS

Thirty-seven controls (10 healthy, 14 CF, 13 CFTR heterozygotes) and 32 CF suspects (26 children; 6 adults) were enrolled. Six were excluded from formal analyses due to β-adrenergic sweat test failure. In adults, evaporimetry was superior to SCT for diagnosis of CF with β-adrenergic:cholinergic ratio TEWL ≤ 0.05 achieving 100% sensitivity and specificity. Twenty-two CF suspect children (age range: 3.4-15.6 years) completed β-adrenergic sweat testing of which none had CF confirmed by genotyping: β-adrenergic:cholinergic ratio > 0.05 successfully excluded CF in all but one child who was CFTR heterozygous. Median peak β-adrenergic TEWL and β-adrenergic:cholinergic ratio in CFTR negative and CFTR heterozygous children was significantly lower than adult controls.

CONCLUSION

β-adrenergic sweat test is more accurate than SCT for excluding CF in children with inconclusive diagnosis. Established reference ranges for β-adrenergic sweat test may not be suitable for children due to lower β-adrenergic sweat secretion compared to adults.

Analysis of INSPPIRE-2 Cohort: Risk Factors and Disease Burden in Children With Acute Recurrent or Chronic Pancreatitis

OBJECTIVES

The objective of this study is to investigate risk factors and disease burden in pediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP).

METHODS

Data were obtained from INternational Study group of Pediatric Pancreatitis: In search for a cuRE-2 (INSPPIRE-2), the largest multi-center prospective cohort study in pediatric patients with ARP or CP.

RESULTS

Of 689 children, 365 had ARP (53%), 324 had CP (47%). CP was more commonly associated with female sex, younger age at first acute pancreatitis (AP) attack, Asian race, family history of CP, lower BMI%, genetic and obstructive factors, PRSS1 mutations and pancreas divisum. CFTR mutations, toxic-metabolic factors, medication use, hypertriglyceridemia, Crohn disease were more common in children with ARP. Constant or frequent abdominal pain, emergency room (ER) visits, hospitalizations, medical, endoscopic or surgical therapies were significantly more common in CP, episodic pain in ARP. A total of 33.1% of children with CP had exocrine pancreatic insufficiency (EPI), 8.7% had diabetes mellitus. Compared to boys, girls were more likely to report pain impacting socialization and school, medical therapies, cholecystectomy, but no increased opioid use. There was no difference in race, ethnicity, age at first AP episode, age at CP diagnosis, duration of disease, risk factors, prevalence of EPI or diabetes between boys and girls. Multivariate analysis revealed that family history of CP, constant pain, obstructive risk factors were predictors of CP.

CONCLUSIONS

Children with family history of CP, constant pain, or obstructive risk factors should raise suspicion for CP.

Health-Related Quality of Life in Pediatric Acute Recurrent or Chronic Pancreatitis: Association With Biopsychosocial Risk Factors

OBJECTIVES

Abdominal pain, emergency department visits, and hospitalizations impact lives of children with acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP). Data on health-related quality of life (HRQOL) in this population, however, remains limited. We aimed to evaluate HRQOL in children with ARP or CP; and test biopsychosocial risk factors associated with low HRQOL.

METHODS

Data were acquired from the INternational Study Group of Pediatric Pancreatitis: In search for a cuRE registry. Baseline demographic and clinical questionnaires, the Child Health Questionnaire (measures HRQOL) and Child Behavior Checklist (measures emotional and behavioral functioning) were completed at enrollment.

RESULTS

The sample included 368 children (54.3% girls, mean age = 12.7years, standard deviation [SD] = 3.3); 65.2% had ARP and 34.8% with CP. Low physical HRQOL (M = 38.5, SD = 16.0) was demonstrated while psychosocial HRQOL (M = 49.5, SD = 10.2) was in the normative range. Multivariate regression analysis revealed that clinical levels of emotional and behavioral problems (B = -10.28, P  < 0.001), episodic and constant abdominal pain (B = 04.66, P = 0.03; B = -13.25, P < 0.001) were associated with low physical HRQOL, after accounting for ARP/CP status, age, sex, exocrine, and endocrine disease (F [9, 271] = 8.34, P < 0.001). Borderline and clinical levels of emotional and behavioral problems (B = -10.18, P < 0.001; B = -15.98, P < 0.001), and constant pain (B = -4.46, P < 0.001) were associated with low psychosocial HRQOL (F [9, 271] = 17.18, P < 0.001).

CONCLUSIONS

Findings highlight the importance of assessing HRQOL and treating pain and psychosocial problems in this vulnerable group of children.

CFTR interactome mapping using the mammalian membrane two‐hybrid high‐throughput screening system

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a chloride and bicarbonate channel in secretory epithelia with a critical role in maintaining fluid homeostasis. Mutations in CFTR are associated with Cystic Fibrosis (CF), the most common lethal autosomal recessive disorder in Caucasians. While remarkable treatment advances have been made recently in the form of modulator drugs directly rescuing CFTR dysfunction, there is still considerable scope for improvement of therapeutic effectiveness. Here, we report the application of a high‐throughput screening variant of the Mammalian Membrane Two‐Hybrid (MaMTH‐HTS) to map the protein–protein interactions of wild‐type (wt) and mutant CFTR (F508del), in an effort to better understand CF cellular effects and identify new drug targets for patient‐specific treatments. Combined with functional validation in multiple disease models, we have uncovered candidate proteins with potential roles in CFTR function/CF pathophysiology, including Fibrinogen Like 2 (FGL2), which we demonstrate in patient‐derived intestinal organoids has a significant effect on CFTR functional expression.

Outcomes of Cystic Fibrosis Screening-Positive Infants With Inconclusive Diagnosis at School Age

BACKGROUND AND OBJECTIVES

Cystic fibrosis (CF) screen-positive infants with an inconclusive diagnosis (CFSPID) are infants in whom sweat testing and genetic analysis does not resolve a CF diagnosis. Lack of knowledge about the health outcome of these children who require clinical follow-up challenges effective consultation. Early predictive biomarkers to delineate the CF risk would allow a more targeted approach to these children.

METHODS

Prospective, longitudinal, multicenter, Canada-wide cohort study of CF positive-screened newborns with 1 to 2 cystic fibrosis transmembrane conductance regulator gene variants, of which at least 1 is not known to be CF-causing and/or a sweat chloride between 30 and 59 mmol/L. These were monitored for conversion to a CF diagnosis, pulmonary, and nutritional outcomes.

RESULTS

The mean observation period was 7.7 (95% confidence interval 7.1 to 8.4) years. A CF diagnosis was established for 24 of the 115 children with CFSPID (21%) either because of reinterpretation of the cystic fibrosis transmembrane conductance regulator genotype or because of increase in sweat chloride concentration ≥60 mmol/L. An initial sweat chloride of ≥40 mmol/l predicted conversion to CF on the basis of sweat testing. The 91 remaining children with CFSPID were pancreatic sufficient and showed normal growth until school age. Pulmonary function as well as lung clearance index in a subgroup of children with CFSPID were similar to that of healthy controls.

CONCLUSIONS

Children with CFSPID have good nutritional and pulmonary outcomes at school age, but rates of reclassifying the diagnosis are high. The initial sweat chloride test can be used as a biomarker to predict the risk for CF in CFSPID.

Complications of chronic pancreatitis in children

PURPOSE OF REVIEW

In children, chronic pancreatitis is infrequent but may be associated with serious complications, including severe pain that limits activities, exocrine and endocrine pancreatic insufficiency and malnutrition. Investigation into pediatric chronic pancreatitis has transitioned from single center reports to multicenter, protocol-driven studies. As a result, we now have information on much larger numbers of children with chronic pancreatitis, allowing a more reliable understanding of the complications of chronic pancreatitis.

RECENT FINDINGS

A high percentage of children with chronic pancreatitis use opioids frequently to control pain. About a quarter of children with chronic pancreatitis have exocrine pancreatic insufficiency, and about 6% have pancreatogenic diabetes. Mild malnutrition and low bone density are both common in children with chronic pancreatitis.

SUMMARY

Large multicenter and single-center observational studies have allowed us to more accurately assess complications of chronic pancreatitis in children. These studies demonstrate the need for examination of therapies for these complications in children.

Rescue of multiple class II CFTR mutations by elexacaftor+tezacaftor+ivacaftor mediated in part by the dual activities of elexacaftor as both corrector and potentiator

Positive results in pre-clinical studies of the triple combination of elexacaftor, tezacaftor and ivacaftor, performed in airway epithelial cell cultures obtained from patients harbouring the class II cystic fibrosis transmembrane conductance regulator (CFTR) mutation F508del-CFTR, translated to impressive clinical outcomes for subjects carrying this mutation in clinical trials and approval of Trikafta.Encouraged by this correlation, we were prompted to evaluate the effect of the elexacaftor, tezacaftor and ivacaftor triple combination on primary nasal epithelial cultures obtained from individuals with rare class II CF-causing mutations (G85E, M1101K and N1303K) for which Trikafta is not approved.Cultures from individuals homozygous for M1101K responded better than cultures harbouring G85E and N1303K after treatment with the triple combination with respect to improvement in regulated channel function and protein processing. A similar genotype-specific effect of the triple combination was observed when the different mutations were expressed in HEK293 cells, supporting the hypothesis that these modulators may act directly on the mutant proteins. Detailed studies in nasal cultures and HEK293 cells showed that the corrector, elexacaftor, exhibited dual activity as both corrector and potentiator, and suggested that the potentiator activity contributes to its pharmacological activity.These pre-clinical studies using nasal epithelial cultures identified mutation genotypes for which elexacaftor, tezacaftor and ivacaftor may produce clinical responses that are comparable to, or inferior to, those observed for F508del-CFTR.

Intestinal epithelial tight junctions and permeability can be rescued through the regulation of endoplasmic reticulum stress by amniotic fluid stem cells during necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is one of the most severe gastrointestinal diseases affecting premature infants. It has been shown that NEC is associated with disrupted intestinal barrier and dysregulated endoplasmic reticulum (ER)-stress response. It has also been shown that stem cells derived from amniotic fluid (AFSC) rescued intestinal injury in experimental NEC. Herein, we hypothesized that the beneficial effects of AFSC in the injured intestine are due to the restoration of intestinal barrier function. We evaluated intestinal barrier function using an ex vivo intestinal organoid model of NEC. We found that AFSC restored the expression and localization of tight junction proteins in intestinal organoids, and subsequently decreased epithelial permeability. AFSC rescued tight junction expression by inducing a protective ER stress response that prevents epithelial cell apoptosis in injured intestinal organoids. Finally, we validated these results in our experimental mouse model of NEC and confirmed that AFSC induced sustained ER stress and prevented intestinal apoptosis. This response led to the restoration of tight junction expression and localization, which subsequently reduced intestinal permeability in NEC pups. These findings confirm that intestinal barrier function is disrupted during NEC intestinal injury, and further demonstrate the disruption can be reversed by the administration of AFSC through the activation of the ER stress pathway. This study provides insight into the pathogenesis of NEC and highlights potential therapeutic targets for the treatment of NEC.

Pediatric Acute Pancreatitis: Changes in Management and Disease Outcomes Over 16 Years

OBJECTIVE

To examine the changes over time of pediatric acute pancreatitis (AP) severity, management, and disease outcomes at our academic tertiary center.

METHODS

We reviewed 223 pediatric AP admissions (2002-2018) and used a time-to-event regression model to study changes over time. Disease outcomes were analyzed using a subgroup of 89 patients in whom only the AP event determined length of hospital stay and duration of opioid use.

RESULTS

There was an increase in mild, but not severe, AP episodes over the examined period. June 2014 was identified as a single cutoff point for change in AP management and disease outcomes independent of each other and of disease severity. Timing of initiating enteral nutrition decreased from 5 to 1.6 days (P < 0.0001) in the entire cohort and from 4.1 to 1.8 days in the subgroup (P = 0.0001) after June 2014. Length of hospitalization decreased from 6 to 3.3 days (P = 0.0008) and days of opioid use from 4.1 to 1.3 (P = 0.002) after June 2014.

CONCLUSIONS

Timing of initiating enteral nutrition has significantly reduced at our center after June 2014. In parallel, we observed a significant improvement in disease outcomes.

A helper-dependent adenoviral vector rescues CFTR to wild-type functional levels in cystic fibrosis epithelial cells harbouring class I mutations

Cystic fibrosis (CF) is a genetic disorder affecting multiple organs, including the pancreas, hepatobiliary system and reproductive organs; however, lung disease is responsible for the majority of morbidity and mortality. Management of CF involves CF transmembrane conductance regulator (CFTR) modulator agents including corrector drugs to augment cellular trafficking of mutant CFTR as well as potentiators that open defective CFTR channels. These therapies are poised to help most individuals with CF, with the notable exception of individuals with class I mutations where full-length CFTR protein is not produced. For these mutations, gene replacement has been suggested as a potential solution.In this work, we used a helper-dependent adenoviral vector (HD-CFTR) to express CFTR in nasal epithelial cell cultures derived from CF subjects with class I CFTR mutations.CFTR function was significantly restored in CF cells by HD-CFTR and reached healthy control functional levels as detected by Ussing chamber and membrane potential (FLIPR) assay. A dose-response relationship was observed between the amount of vector used and subsequent functional outcomes; small amounts of HD-CFTR were sufficient to correct CFTR function. At higher doses, HD-CFTR did not increase CFTR function in healthy control cells above baseline values. This latter observation allowed us to use this vector to benchmark in vitro efficacy testing of CFTR-modulator drugs.In summary, we demonstrate the potential for HD-CFTR to inform in vitro testing and to restore CFTR function to healthy control levels in airway cells with class I or CFTR nonsense mutations.

Preclinical Studies of a Rare CF-Causing Mutation in the Second Nucleotide Binding Domain (c.3700A>G) Show Robust Functional Rescue in Primary Nasal Cultures by Novel CFTR Modulators

The combination therapies ORKAMBI^TM and TRIKAFTA^TM are approved for people who have the F508del mutation on at least one allele. In this study we examine the effects of potentiator and corrector combinations on the rare mutation c.3700A>G. This mutation produces a cryptic splice site that deletes six amino acids in NBD2 (I1234-R1239del). Like F508del it causes protein misprocessing and reduced chloride channel function. We show that a novel cystic fibrosis transmembrane conductance regulator CFTR modulator triple combination (AC1, corrector, AC2-2, co-potentiator and AP2, potentiator), rescued I1234-R1239del-CFTR activity to WT-CFTR level in HEK293 cells. Moreover, we show that although the response to ORKAMBI was modest in nasal epithelial cells from two individuals homozygous for I1234-R1239del-CFTR, a substantial functional rescue was achieved with the novel triple combination. Interestingly, while both the novel CFTR triple combination and TRIKAFTA^TM treatment showed functional rescue in gene-edited I1234-R1239del-CFTR-expressing HBE cells and in nasal cells from two CF patients heterozygous for I1234-R1239del/W1282X, nasal cells homozygous for I1234-R1239del-CFTR showed no significant response to the TRIKAFTA^TM combination. These data suggest a potential benefit of CFTR modulators on the functional rescue of I1234-R1239del -CFTR, which arises from the rare CF-causing mutation c.3700A>G, and highlight that patient tissues are crucial to our full understanding of functional rescue in rare CFTR mutations.

DIGEST: Developing innovative gastroenterology specialty training

•

There is a need for adult and pediatric gastroenterologists with expertise in CF.

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The DIGEST program was created to meet this need.

•

This article reports on the development, implementation and results of DIGEST.

Individuals with cystic fibrosis (CF) now have an increased life expectancy, due to advances in care provided by a multidisciplinary team. The care model has expanded over time to include multiple subspecialties. The Cystic Fibrosis Foundation conducted a survey of Care Center Directors and identified a need for pediatric and adult gastroenterologists with expertise in the diagnosis and treatment of intestinal, pancreatic and hepatic complications of CF. To address this need, the Developing Innovative GastroEnterology Specialty Training (DIGEST) program was created. The development, implementation, and early results of this training program are reported herein.

Emerging preclinical modulators developed for F508del-CFTR have the potential to be effective for ORKAMBI resistant processing mutants

BACKGROUND

F508del is prototypical of Class 2 CFTR mutations associated with protein misprocessing and reduced function. Corrector compounds like lumacaftor partially rescue the processing defect of F508del-CFTR whereas potentiators like ivacaftor, enhance its channel activity once trafficked to the cell surface. We asked if emerging modulators developed for F508del-CFTR can rescue Class 2 mutations previously shown to be poorly responsive to lumacaftor and ivacaftor.

METHODS

Rescue of mutant CFTRs by the correctors: AC1, AC2-1 or AC2-2 and the potentiator, AP2, was studied in HEK-293 cells and in primary human nasal epithelial (HNE) cultures, using a membrane potential assay and Ussing chamber, respectively.

RESULTS

In HEK-293 cells, we found that a particular combination of corrector molecules (AC1 plus AC2-1) and a potentiator (AP2) was effective in rescuing both the misprocessing and reduced function of M1101K and G85E respectively. These findings were recapitulated in patient-derived nasal cultures, although another corrector combination, AC1 plus AC2-2 also improved misprocessing in these primary tissues. Interestingly, while this corrector combination only led to a modest increase in the abundance of mature N1303K-CFTR it did enable its functional expression in the presence of the potentiator, AP2, in part, because the nominal corrector, AC2-2 also exhibits potentiator activity.

CONCLUSIONS

Strategic combinations of novel modulators can potentially rescue Class 2 mutants thought to be relatively unresponsive to lumacaftor and ivacaftor.

Augmentation of Cystic Fibrosis Transmembrane Conductance Regulator Function in Human Bronchial Epithelial Cells via SLC6A14-Dependent Amino Acid Uptake. Implications for Treatment of Cystic Fibrosis

SLC6A14-mediated l-arginine transport has been shown to augment the residual anion channel activity of the major mutant, F508del-CFTR, in the murine gastrointestinal tract. It is not yet known if this transporter augments residual and pharmacological corrected F508del-CFTR in primary airway epithelia. We sought to determine the role of l-arginine uptake via SLC6A14 in modifying F508del-CFTR channel activity in airway cells from patients with cystic fibrosis (CF). Human bronchial epithelial (HBE) cells from lung explants of patients without CF (HBE) and those with CF (CF-HBE) were used for H³-flux, airway surface liquid, and Ussing chamber studies. We used α-methyltryptophan as a specific inhibitor for SLC6A14. CFBE41o^-, a commonly used CF airway cell line, was employed for studying the mechanism of the functional interaction between SLC6A14 and F508del-CFTR. SLC6A14 is functionally expressed in CF-HBE cells. l-arginine uptake via SLC6A14 augmented F508del-CFTR function at baseline and after treatment with lumacaftor. SLC6A14-mediated l-arginine uptake also increased the airway surface liquid in CF-HBE cells. Using CFBE41o cells, we showed that the positive SLC6A14 effect was mainly dependent on the nitric oxide (NO) synthase activity, nitrogen oxides, including NO, and phosphorylation by protein kinase G. These finding were confirmed in CF-HBE, as inducible NO synthase inhibition abrogated the functional interaction between SLC6A14 and pharmacological corrected F508del-CFTR. In summary, SLC6A14-mediated l-arginine transport augments residual F508del-CFTR channel function via a noncanonical, NO pathway. This effect is enhanced with increasing pharmacological rescue of F508del-CFTR to the membrane. The current study demonstrates how endogenous pathways can be used for the development of companion therapy in CF.

A110 DGAT1 MUTATION OF LIPID TRAFFICKING ASSOCIATED WITH A RARE CASE OF CONGENITAL DIARRHEA

Background

Congenital diarrheas and enteropathies (CODEs) are rare and cause severe chronic diarrhea in children under 2 years of age.1 Current genomic research has identified several monogenic defects resulting in epithelial disorders of nutrient and electrolyte transport, enzymes function, metabolism and trafficking.

Aims

To discuss a rare case of congential diarrhea.

Methods

Case Report.

Results

A 10-month-old Ashkenazi Jewish boy was referred to Pediatric Gastroenterology for loose stools and failure to thrive. Born at 27 weeks, he was a NICU inpatient for his first 3 months of life. Explosive loose stools were first noticed after discharge and treated as cow’s milk protein allergy. At aged 10 months he was admitted to his local hospital with irritability, abdominal distension, foul smelling loose stools and developmental delay. Despite an intake of 130kcal/kg/day he failed to gain weight (weight and length &lt; 3rd centile). His abdomen was distended but there was no organomegaly on examination.

On transfer to Sick Kids he underwent extensive work up with low albumin 24 g/L but normal CBC, amylase, lipase and IgA and

anti-TTG negative. The lipid profile showed hypertriglyceridemia 2.98 mmol/L (normal &lt;0.85), low HDL 0.81 mmol/L but normal total cholesterol. Low apoliprotein A1 0.79 g/L (0.92 - 1.96), low apoliprotein B 0.54 g (0.59 - 1.46) and vitamin E deficiency 9.6 umol/L (14.5 - 33.0). Normal fecal elastase (&gt; 500 ug/g stool). Upper GI endoscopy showed duodenal villi blunting with non-specific chronic inactive duodenitis on histopathology.

Due to ongoing poor weight gain he commenced TPN. A repeat endoscopy four weeks after admission revealed patchy villous blunting, crypt hyperplasia and enterocyte vacuolization. However, ultrastructural electron microscopy examination showed normal enterocyte brush border with well-formed microvilli with no inclusions or vesicular bodies. With a differential diagnosis of chylomicron retention disorder, abetalipoproteinemia or hypolipoproteinemia he was commenced on a low-fat diet with MCT feeds. A 72-hour fecal fat collection on this diet was within normal range 5.4 mmol/day (2–7).

One year later his weight is now on 3rd centile and his albumin levels have normalized. However, triglycerides remain elevated. Whole exome sequencing identified two pathogenic variants in the DGAT1 gene; c.629_631delCCT, pSer210del and c751 + 2T&gt;C, IVSB+2T&gt;C.

Conclusions

Diacylglycerol acyltransferase (DGAT)1 catalyzes triglyceride biosynthesis.2 Loss of function DGAT1 gene mutations are described in several cases studies3,4 characterized by electrolyte transport–related diarrhea, protein-losing enteropathy and growth failure. Our cases adds to the understanding of the phenotypic and histological spectrum of DGAT1 mutations. Management strategies currently focus on growth with dietary lipid restriction, while substituting fat-soluble vitamins and essential fatty acids.

Funding Agencies

CAG

Factors Associated With Frequent Opioid Use in Children With Acute Recurrent and Chronic Pancreatitis

OBJECTIVES

The aim of the study was to understand the association of frequent opioid use with disease phenotype and pain pattern and burden in children and adolescents with acute recurrent (ARP) or chronic pancreatitis (CP).

METHODS

Cross-sectional study of children <19 years with ARP or CP, at enrollment into the INSPPIRE cohort. We categorized patients as opioid "frequent use" (daily/weekly) or "nonfrequent use" (monthly or less, or no opioids), based on patient and parent self-report.

RESULTS

Of 427 children with ARP or CP, 17% reported frequent opioid use. More children with CP (65%) reported frequent opioid use than with ARP (41%, P = 0.0002). In multivariate analysis, frequent opioid use was associated with older age at diagnosis (odds ratio [OR] 1.67 per 5 years, 95% confidence interval [CI] 1.13-2.47, P = 0.01), exocrine insufficiency (OR 2.44, 95% CI 1.13-5.24, P = 0.02), constant/severe pain (OR 4.14, 95% CI 2.06-8.34, P < 0.0001), and higher average pain impact score across all 6 functional domains (OR 1.62 per 1-point increase, 95% CI 1.28-2.06, P < 0.0001). Children with frequent opioid use also reported more missed school days, hospitalizations, and emergency room visits in the past year than children with no frequent use (P < 0.0002 for each). Participants in the US West and Midwest accounted for 83% of frequent opioid users but only 56% of the total cohort.

CONCLUSIONS

In children with CP or ARP, frequent opioid use is associated with constant pain, more healthcare use, and higher levels of pain interference with functioning. Longitudinal and prospective research is needed to identify risk factors for frequent opioid use and to evaluate nonopioid interventions for reducing pain and disability in these children.

Functional rescue of c.3846G>A (W1282X) in patient-derived nasal cultures achieved by inhibition of nonsense mediated decay and protein modulators with complementary mechanisms of action

BACKGROUND

The nonsense mutation, c.3846G>A (aka: W1282X-CFTR) leads to a truncated transcript that is susceptible to nonsense-mediated decay (NMD) and produces a shorter protein that is unstable and lacks normal channel activity in patient-derived tissues. However, if overexpressed in a heterologous expression system, the truncated mutant protein has been shown to mediate CFTR channel function following the addition of potentiators. In this study, we asked if a quadruple combination of small molecules that together inhibit nonsense mediated decay, stabilize both halves of the mutant protein and potentiate CFTR channel activity could rescue the functional expression of W1282X-CFTR in patient derived nasal cultures.

METHODS

We identified the CFTR domains stabilized by corrector compounds supplied from AbbVie using a fragment based, biochemical approach. Rescue of the channel function of W1282X.-CFTR protein by NMD inhibition and small molecule protein modulators was studied using a bronchial cell line engineered to express W1282X and in primary nasal epithelial cultures derived from four patients homozygous for this mutation.

RESULTS

We confirmed previous studies showing that inhibition of NMD using the inhibitor: SMG1i, led to an increased abundance of the shorter transcript in a bronchial cell line. Interestingly, on top of SMG1i, treatment with a combination of two new correctors developed by Galapagos/AbbVie (AC1 and AC2-2, separately targeting either the first or second half of CFTR and promoting assembly, significantly increased the potentiated channel activity by the mutant in the bronchial epithelial cell line and in patient-derived nasal epithelial cultures. The average rescue effect in primary cultures was approximately 50% of the regulated chloride conductance measured in non-CF cultures.

CONCLUSIONS

These studies provide the first in-vitro evidence in patient derived airway cultures that the functional defects incurred by W1282X, has the potential to be effectively repaired pharmacologically.

Web-based cognitive-behavioral intervention for pain in pediatric acute recurrent and chronic pancreatitis: Protocol of a multicenter randomized controlled trial from the study of chronic pancreatitis, diabetes and pancreatic cancer (CPDPC)

INTRODUCTION

Abdominal pain is common and is associated with high disease burden and health care costs in pediatric acute recurrent and chronic pancreatitis (ARP/CP). Despite the strong central component of pain in ARP/CP and the efficacy of psychological therapies for other centralized pain syndromes, no studies have evaluated psychological pain interventions in children with ARP/CP. The current trial seeks to 1) evaluate the efficacy of a psychological pain intervention for pediatric ARP/CP, and 2) examine baseline patient-specific genetic, clinical, and psychosocial characteristics that may predict or moderate treatment response.

METHODS

This single-blinded randomized placebo-controlled multicenter trial aims to enroll 260 youth (ages 10-18) with ARP/CP and their parents from twenty-one INSPPIRE (INternational Study Group of Pediatric Pancreatitis: In search for a cuRE) centers. Participants will be randomly assigned to either a web-based cognitive behavioral pain management intervention (Web-based Management of Adolescent Pain Chronic Pancreatitis; WebMAP; N = 130) or to a web-based pain education program (WebED; N = 130). Assessments will be completed at baseline (T1), immediately after completion of the intervention (T2) and at 6 months post-intervention (T3). The primary study outcome is abdominal pain severity. Secondary outcomes include pain-related disability, pain interference, health-related quality of life, emotional distress, impact of pain, opioid use, and healthcare utilization.

CONCLUSIONS

This is the first clinical trial to evaluate the efficacy of a psychological pain intervention for children with CP for reduction of abdominal pain and improvement of health-related quality of life. Findings will inform delivery of web-based pain management and potentially identify patient-specific biological and psychosocial factors associated with favorable response to therapy. Clinical Trial Registration #: NCT03707431.

Immunoreactive trypsinogen levels in newborn screened infants with an inconclusive diagnosis of cystic fibrosis

Background

Newborn screening (NBS) for cystic fibrosis (CF) not only identifies infants with a diagnosis of CF, but also those with an uncertain diagnosis of cystic fibrosis (CF), i.e. CF transmembrane conductance regulator (CFTR)-related metabolic syndrome (CRMS) or CF screen positive inconclusive diagnosis (CFSPID). These infants have an uncertain long-term outcome and it is currently unclear around time of diagnosis, which infants are at higher risk of later fulfilling a CF diagnosis. In this study, we hypothesised that immunoreactive trypsinogen (IRT) levels, used in NBS as a marker of pancreatic disease and function, may reflect the degree of CFTR dysfunction in each individual and therefore would help to identify those with CRMS/CSPID who are later at risk for meeting the criteria of CF.

Methods

In this longitudinal, prospective study, infants with CRMS/CFSPID and CF were recruited and followed in 9 CF clinics (Canada and Italy). We compared NBS IRT levels between CF and CRMS/CFSPID, and between children with CRMS/CFSPID→CF and CRMS/CFSPID→CRMS/CFSPID during the period of June 2007 to April 2016.

Results

Ninety eight CRMS/CFSPID and 120 CF subjects were enrolled. During the study period, 14 (14.3%) CRMS/CFSPID subjects fulfilled the diagnostic criteria for CF (CRMS/CFSPID→CF), while the diagnosis remained uncertain (CRMS/CFSPID→ CRMS/CFSPID) in 84 (85.7%) subjects. Significantly higher NBS IRT concentrations (ng/ml) were present in CF than CRMS/CFPSID (median (interquartile range): 143.8 (99.8–206.2) vs. 75.0 (61.0–105.9); P < 0.0001). Infants with CRMS/CFSPID→CF (n = 14) had significantly higher NBS IRT concentrations (ng/ml) than CRMS/CFSPID→ CRMS/CFSPID (n = 83) (median (interquartile range): 108.9 (72.3–126.8) vs. 73.7(60.0–96.0); P = 0.02).

Conclusions

Amongst infants who tested positive on NBS for CF, there is a gradation of elevated NBS IRT concentrations. Infants with CF have higher NBS IRT levels than CRMS/CFPSID, and higher NBS IRT concentrations were present in infants with CRMS/CFSPID→CF than CRMS/CFSPID→ CRMS/CFSPID. NBS IRT concentrations, in concert with other factors, may have the potential to predict the likelihood of CF amongst infants with CRMS/CFSPID.

ORKAMBI-Mediated Rescue of Mucociliary Clearance in Cystic Fibrosis Primary Respiratory Cultures Is Enhanced by Arginine Uptake, Arginase Inhibition, and Promotion of Nitric Oxide Signaling to the Cystic Fibrosis Transmembrane Conductance Regulator Channel

ORKAMBI, a combination of the corrector, lumacaftor, and the potentiator, ivacaftor, partially rescues the defective processing and anion channel activity conferred by the major cystic fibrosis-causing mutation, F508del, in in vitro studies. Clinically, the improvement in lung function after ORKAMBI treatment is modest and variable, prompting the search for complementary interventions. As our previous work identified a positive effect of arginine-dependent nitric oxide signaling on residual F508del-Cftr function in murine intestinal epithelium, we were prompted to determine whether strategies aimed at increasing arginine would enhance F508del-cystic fibrosis transmembrane conductance regulator (CFTR) channel activity in patient-derived airway epithelia. Now, we show that the addition of arginine together with inhibition of intracellular arginase activity increased cytosolic nitric oxide and enhanced the rescue effect of ORKAMBI on F508del-CFTR-mediated chloride conductance at the cell surface of patient-derived bronchial and nasal epithelial cultures. Interestingly, arginine addition plus arginase inhibition also enhanced ORKAMBI-mediated increases in ciliary beat frequency and mucociliary movement, two in vitro CF phenotypes that are downstream of the channel defect. This work suggests that strategies to manipulate the arginine-nitric oxide pathway in combination with CFTR modulators may lead to improved clinical outcomes. SIGNIFICANCE STATEMENT: These proof-of-concept studies highlight the potential to boost the response to cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulators, lumacaftor and ivacaftor, in patient-derived airway tissues expressing the major CF-causing mutant, F508del-CFTR, by enhancing other regulatory pathways. In this case, we observed enhancement of pharmacologically rescued F508del-CFTR by arginine-dependent, nitric oxide signaling through inhibition of endogenous arginase activity.

Impact of CFTR modulation with Ivacaftor on Gut Microbiota and Intestinal Inflammation

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Next to progressive airway disease, CF is also associated with intestinal inflammation and dysbiosis. Ivacaftor, a CFTR potentiator, has improved pulmonary and nutritional status but its effects on the intestinal microbiota and inflammation are unclear. Hence, we assessed the changes on the intestinal microbial communities (16S rRNA variable 3 gene region) and inflammatory markers (calprotectin and M2-pyruvate kinase [M2-PK]) in 16 CF individuals (8 children and 8 adults) before and after (median 6.1 months) ivacaftor. Stool calprotectin significantly decreased following ivacaftor (median [IQR]: 154.4 [102.1–284.2] vs. 87.5 [19.5–190.2] mg/kg, P = 0.03). There was a significant increase in Akkermansia with ivacaftor. Increased abundance of Akkermansia was associated with normal stool M2-PK concentrations, and decreased abundances of Enterobacteriaceae correlated with decreased stool calprotectin concentrations. In summary, changes in the gut microbiome and decrease in intestinal inflammation was associated with Ivacaftor treatment among individuals with CF carrying at least one gating CFTR mutation. Thus, CFTR-modifying therapy may adequately improve the aberrant pathophysiology and milieu of the CF gut to favor a more healthy microbiota, which in turn reduces intestinal inflammation.

Orkambi® and amplifier co-therapy improves function from a rare CFTR mutation in gene-edited cells and patient tissue

The combination therapy of lumacaftor and ivacaftor (Orkambi^®) is approved for patients bearing the major cystic fibrosis (CF) mutation: ΔF508. It has been predicted that Orkambi^® could treat patients with rarer mutations of similar “theratype”; however, a standardized approach confirming efficacy in these cohorts has not been reported. Here, we demonstrate that patients bearing the rare mutation: c.3700 A>G, causing protein misprocessing and altered channel function—similar to ΔF508‐CFTR, are unlikely to yield a robust Orkambi^® response. While in silico and biochemical studies confirmed that this mutation could be corrected and potentiated by lumacaftor and ivacaftor, respectively, this combination led to a minor in vitro response in patient‐derived tissue. A CRISPR/Cas9‐edited bronchial epithelial cell line bearing this mutation enabled studies showing that an “amplifier” compound, effective in increasing the levels of immature CFTR protein, augmented the Orkambi^® response. Importantly, this “amplifier” effect was recapitulated in patient‐derived nasal cultures—providing the first evidence for its efficacy in augmenting Orkambi^® in tissues harboring a rare CF‐causing mutation. We propose that this multi‐disciplinary approach, including creation of CRISPR/Cas9‐edited cells to profile modulators together with validation using primary tissue, will facilitate therapy development for patients with rare CF mutations.

Autoimmune Pancreatitis in Children: Characteristic Features, Diagnosis, and Management

OBJECTIVES

Autoimmune pancreatitis (AIP) is an increasingly recognized disease entity, but data in children are limited. AIP presentation and outcome in children might differ from the adult experience. We aim to determine the characteristic features of AIP in children.

METHODS

Data about clinical symptoms, imaging, histology, and treatment were collected using two sources: (i) a systematic literature search and (ii) the INSPPIRE database, the largest international multicenter study of pancreatitis in children and the Cliniques Universitaires St-Luc (CUSL) registry.

RESULTS

We identified 48 AIP cases: 30 from literature review, 14 from INSPPIRE, and 4 from CUSL. The median age at diagnosis was 13 years (range 2-17 years). Abdominal pain (43/47, 91%) and/or obstructive jaundice (20/47, 42%) were the most common symptoms at diagnosis. Elevated serum IgG4 levels were only observed in 9/40 (22%) children. Cross-sectional imaging studies were abnormal in all children including hypointense global or focal gland enlargement (39/47, 83%), main pancreatic duct irregularity (30/47, 64%), and common bile duct stricture (26/47, 55%). A combination of lymphoplasmacytic inflammation, pancreatic fibrosis, and ductal granulocyte infiltration were the main histological findings (18/25, 72%). Children with AIP had a prompt clinical response to steroids. Complications of AIP included failure of exocrine (4/25, 16%) and endocrine (3/27, 11%) pancreas function.

CONCLUSIONS

Pediatric AIP has a distinct presentation with features similar to type 2 AIP in adults. This comprehensive report on the largest group of children with AIP to date is expected to help with the diagnosis and management of this disease and pave the way for future research studies.

The Sweat Metabolome of Screen-Positive Cystic Fibrosis Infants: Revealing Mechanisms beyond Impaired Chloride Transport

The sweat chloride test remains the gold standard for confirmatory diagnosis of cystic fibrosis (CF) in support of universal newborn screening programs. However, it provides ambiguous results for intermediate sweat chloride cases while not reflecting disease progression when classifying the complex CF disease spectrum given the pleiotropic effects of gene modifiers and environment. Herein we report the first characterization of the sweat metabolome from screen-positive CF infants and identify metabolites associated with disease status that complement sweat chloride testing. Pilocarpine-stimulated sweat specimens were collected independently from two CF clinics, including 50 unaffected infants (e.g., carriers) and 18 confirmed CF cases. Nontargeted metabolite profiling was performed using multisegment injection-capillary electrophoresis-mass spectrometry as a high throughput platform for analysis of polar/ionic metabolites in volume-restricted sweat samples. Amino acids, organic acids, amino acid derivatives, dipeptides, purine derivatives, and unknown exogenous compounds were identified in sweat when using high resolution tandem mass spectrometry, including metabolites associated with affected yet asymptomatic CF infants, such as asparagine and glutamine. Unexpectedly, a metabolite of pilocarpine, used to stimulate sweat secretion, pilocarpic acid, and a plasticizer metabolite from environmental exposure, mono(2-ethylhexyl)phthalic acid, were secreted in the sweat of CF infants at significantly lower concentrations relative to unaffected CF screen-positive controls. These results indicated a deficiency in human paraoxonase, an enzyme unrelated to mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) and impaired chloride transport, which is a nonspecific arylesterase/lactonase known to mediate inflammation, bacterial biofilm formation, and recurrent lung infections in affected CF children later in life. This work sheds new light into the underlying mechanisms of CF pathophysiology as required for new advances in precision medicine of orphan diseases that benefit from early detection and intervention, including new molecular targets for therapeutic intervention.

Psychosocial Response to Uncertain Newborn Screening Results for Cystic Fibrosis

OBJECTIVE

To explore the psychosocial implications of diagnostic uncertainty that result from inconclusive results generated by newborn bloodspot screening (NBS) for cystic fibrosis (CF).

STUDY DESIGN

Using a mixed methods prospective cohort study of children who received NBS for CF, we compared psychosocial outcomes of parents whose children who received persistently inconclusive results with those whose children received true positive or screen-negative results.

RESULTS

Mothers of infants who received inconclusive results (n = 17), diagnoses of CF (n = 15), and screen-negative results (n = 411) were surveyed; 23 parent interviews were completed. Compared with mothers of infants with true positive/screen-negative results, mothers of infants with inconclusive results reported greater perceived uncertainty (P < .006) but no differences in anxiety or vulnerability (P > .05). Qualitatively, parents valued being connected to experts but struggled with the meaning of an uncertain diagnosis, worried about their infant's health-related vulnerability, and had mixed views about surveillance.

CONCLUSION

Inconclusive CF NBS results were not associated with anxiety or vulnerability but led to health-related uncertainty and qualitative concerns. Findings should be considered alongside efforts to optimize protocols for CF screening and surveillance. Educational and psychosocial supports are warranted for these families.

Cystic Fibrosis Transmembrane Conductance Regulator-Related Metabolic Syndrome and Cystic Fibrosis Screen Positive, Inconclusive Diagnosis

OBJECTIVE

An unintended consequence of cystic fibrosis (CF) newborn screening (NBS) is the identification of infants with a positive NBS test but inconclusive diagnostic testing. These infants are classified as CF transmembrane conductance regulator-related metabolic syndrome (CRMS) in the US and CF screen positive, inconclusive diagnosis (CFSPID) in other countries. Diagnostic and management decisions of these infants are challenges for CF healthcare professionals and stressful situations for families. As CF NBS has become more widespread across the world, increased information about the epidemiology and outcomes of these infants is becoming available. These data were reviewed at the 2015 CF Foundation Diagnosis Consensus Conference, and a harmonized definition of CRMS and CFSPID was developed.

STUDY DESIGN

At the consensus conference, participants reviewed published and unpublished studies of CRMS/CFSPID and used a modified Delphi methodology to develop a harmonized approach to the definition of CRMS/CFSPID.

RESULTS

Several studies of CRMS/CFSPID from populations around the world have been published in the past year. Although the studies vary in the number of infants studied, study design, and outcome measures, there have been some consistent findings. CRMS/CFSPID occurs relatively frequently, with CF:CRMS that ranges from 3 to 5 cases of CF for every 1 case of CRMS/CFSPID in regions where gene sequencing is not used. The incidence varies by NBS protocol used, and in some regions more cases of CRMS/CFSPID are detected than cases of CF. The majority of individuals with CRMS/CFSPID do not develop CF disease or progress to a diagnosis of CF. However, between 10% and 20% of asymptomatic infants can develop clinical features concerning for CF, such as a respiratory culture positive for Pseudomonas aeruginosa. Most studies have only reported short-term outcomes in the first 1-3 years of life; the long-term outcomes of CRMS/CFSPID remain unknown. The European CF Society definition of CFSPID and the CF Foundation definition of CRMS differ only slightly, and the consensus conference was able to create a unified definition of CRMS/CFSPID.

CONCLUSIONS

CRMS/CFSPID is a relatively common outcome of CF NBS, and clinicians need to be prepared to counsel families whose NBS test falls into this classification. The vast majority of infants with CRMS/CFSPID will remain free from disease manifestations early in life. However, a small proportion may develop clinical features concerning for CF or demonstrate progression to a clinical phenotype compatible with a CF diagnosis, and their long-term outcomes are not known. A consistent international definition of CRMS/CFSPID will allow for better data collection for study of outcomes and result in improved patient care.

Causal Evaluation of Acute Recurrent and Chronic Pancreatitis in Children: Consensus From the INSPPIRE Group

OBJECTIVES

Acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) have been diagnosed in children at increasing rates during the past decade. As pediatric ARP and CP are still relatively rare conditions, little quality evidence is available on which to base the diagnosis and determination of etiology. The aim of the study was to review the current state of the literature regarding the etiology of these disorders and to developed a consensus among a panel of clinically active specialists caring for children with these disorders to help guide the diagnostic evaluation and identify areas most in need of future research.

METHODS

A systematic review of the literature was performed and scored for quality, followed by consensus statements developed and scored by each individual in the group for level of agreement and strength of the supporting data using a modified Delphi method. Scores were analyzed for the level of consensus achieved by the group.

RESULTS

The panel reached consensus on 27 statements covering the definitions of pediatric ARP and CP, evaluation for potential etiologies of these disorders, and long-term monitoring. Statements for which the group reached consensus to make no recommendation or could not reach consensus are discussed.

CONCLUSIONS

This consensus helps define the minimal diagnostic evaluation and monitoring of children with ARP and CP. Even in areas in which we reached consensus, the quality of the evidence is weak, highlighting the need for further research. Improved understanding of the underlying cause will facilitate treatment development and targeting.

Cystic fibrosis gene modifier SLC26A9 modulates airway response to CFTR-directed therapeutics

Cystic fibrosis is realizing the promise of personalized medicine. Recent advances in drug development that target the causal CFTR directly result in lung function improvement, but variability in response is demanding better prediction of outcomes to improve management decisions. The genetic modifier SLC26A9 contributes to disease severity in the CF pancreas and intestine at birth and here we assess its relationship with disease severity and therapeutic response in the airways. SLC26A9 association with lung disease was assessed in individuals from the Canadian and French CF Gene Modifier consortia with CFTR-gating mutations and in those homozygous for the common Phe508del mutation. Variability in response to a CFTR-directed therapy attributed to SLC26A9 genotype was assessed in Canadian patients with gating mutations. A primary airway model system determined if SLC26A9 shows modification of Phe508del CFTR function upon treatment with a CFTR corrector. In those with gating mutations that retain cell surface-localized CFTR we show that SLC26A9 modifies lung function while this is not the case in individuals homozygous for Phe508del where cell surface expression is lacking. Treatment response to ivacaftor, which aims to improve CFTR-channel opening probability in patients with gating mutations, shows substantial variability in response, 28% of which can be explained by rs7512462 in SLC26A9 (P = 0.0006). When homozygous Phe508del primary bronchial cells are treated to restore surface CFTR, SLC26A9 likewise modifies treatment response (P = 0.02). Our findings indicate that SLC26A9 airway modification requires CFTR at the cell surface, and that a common variant in SLC26A9 may predict response to CFTR-directed therapeutics.

Parent Experience With False-Positive Newborn Screening Results for Cystic Fibrosis

BACKGROUND

The risk of psychosocial harm in families of infants with false-positive (FP) newborn bloodspot screening (NBS) results for cystic fibrosis (CF) is a longstanding concern. Whether well designed retrieval and confirmatory testing systems can mitigate risks remains unknown.

METHODS

Using a mixed-methods cohort design, we obtained prospective self-report data from mothers of infants with FP CF NBS results 2 to 3 months after confirmatory testing at Ontario's largest follow-up center, and from a randomly selected control sample of mothers of screen negative infants from the same region. Mothers completed a questionnaire assessing experience and psychosocial response. A sample of mothers of FP infants completed qualitative interviews.

RESULTS

One hundred thirty-four mothers of FP infants (response rate, 55%) and 411 controls (response rate, 47%) completed questionnaires; 54 mothers of FP infants were interviewed. Selected psychosocial response measures did not detect psychosocial distress in newborns or 1 year later (P > .05). Mothers recalled distress during notification of the positive result and in the follow-up testing period related to fear of chronic illness, but valued the screening system of care in mitigating concerns.

CONCLUSIONS

Although immediate distress was reported among mothers of FP infants, selected psychometric tools did not detect these concerns. The NBS center from which mothers were recruited minimizes delay between notification and confirmatory testing and ensures trained professionals are communicating results and facilitating follow-up. These factors may explain the presence of minimal psychosocial burden. The screening system reflected herein may be a model for NBS programs working to minimize FP-related psychosocial harm.