Showing papers by "A. Wesley Burks published in 2018"

AR101 Oral Immunotherapy for Peanut Allergy

Abstract: BACKGROUND Peanut allergy, for which there are no approved treatment options, affects patients who are at risk for unpredictable and occasionally life-threatening allergic reactions. METHODS In a phase 3 trial, we screened participants 4 to 55 years of age with peanut allergy for allergic dose-limiting symptoms at a challenge dose of 100 mg or less of peanut protein (approximately one third of a peanut kernel) in a double-blind, placebo-controlled food challenge. Participants with an allergic response were randomly assigned, in a 3:1 ratio, to receive AR101 (a peanut-derived investigational biologic oral immunotherapy drug) or placebo in an escalating-dose program. Participants who completed the regimen (i.e., received 300 mg per day of the maintenance regimen for approximately 24 weeks) underwent a double-blind, placebo-controlled food challenge at trial exit. The primary efficacy end point was the proportion of participants 4 to 17 years of age who could ingest a challenge dose of 600 mg or more, without dose-limiting symptoms. RESULTS Of the 551 participants who received AR101 or placebo, 496 were 4 to 17 years of age; of these, 250 of 372 participants (67.2%) who received active treatment, as compared with 5 of 124 participants (4.0%) who received placebo, were able to ingest a dose of 600 mg or more of peanut protein, without dose-limiting symptoms, at the exit food challenge (difference, 63.2 percentage points; 95% confidence interval, 53.0 to 73.3; P<0.001). During the exit food challenge, the maximum severity of symptoms was moderate in 25% of the participants in the active-drug group and 59% of those in the placebo group and severe in 5% and 11%, respectively. Adverse events during the intervention period affected more than 95% of the participants 4 to 17 years of age. A total of 34.7% of the participants in the active-drug group had mild events, as compared with 50.0% of those in the placebo group; 59.7% and 44.4% of the participants, respectively, had events that were graded as moderate, and 4.3% and 0.8%, respectively, had events that were graded as severe. Efficacy was not shown in the participants 18 years of age or older. CONCLUSIONS In this phase 3 trial of oral immunotherapy in children and adolescents who were highly allergic to peanut, treatment with AR101 resulted in higher doses of peanut protein that could be ingested without dose-limiting symptoms and in lower symptom severity during peanut exposure at the exit food challenge than placebo. (Funded by Aimmune Therapeutics; PALISADE ClinicalTrials.gov number, NCT02635776 .).

Mechanisms of food allergy.

Abstract: Although oral tolerance is the normal physiologic response to ingested antigens, a breakdown in this process appears to have occurred in the past 2 decades, leading to an increasing prevalence of sensitization to food allergens. Over the past decade, basic research has intensified in an attempt to better understand the mechanisms leading to sensitization and disease versus desensitization and short- and long-term tolerance. In this review we assess various factors that can influence tissue and immune responses to food antigens, the current understanding of immune tolerance development, the role of the gastrointestinal microbiota, and current knowledge regarding immunologic mechanisms involved in desensitization and sustained unresponsiveness, although perhaps the latter is more appropriately termed remission.

Treatment for food allergy

Abstract: The prevalence of IgE-mediated food allergy is an increasing public health concern effecting millions of persons worldwide. The current standard of treatment is strict avoidance of the offending food or foods, and to date, there are no regulatory approved treatments for food allergy. A significant amount of research has been directed at various forms of food immunotherapy, including oral, sublingual, and epicutaneous delivery routes. Although oral immunotherapy has shown the greatest promise for efficacy in terms of the amount of protein that can be ingested, it has also demonstrated less tolerability and a less favorable safety profile compared with sublingual immunotherapy and epicutaneous immunotherapy, which offers the least protection but has the best safety and tolerability profile. Studies have been conducted with adding adjuvants and anti-IgE to enhance either the efficacy or safety of food immunotherapy. Multiple concepts of food immunotherapy beyond these first-generation treatments are in either animal or early phase 1 studies.

Food Allergy: Update on Prevention and Tolerance

Abstract: Of the many possible hypotheses that explain the recent increase in childhood food allergy (FA), the dual-allergen exposure hypothesis has been the most extensively investigated. This chapter serves as a review and update on the prevention of FA and focuses on recently published randomized controlled trials exploring the efficacy of oral tolerance induction in infancy for the prevention of FA. As a result of these RCTs, National Institutes of Health recommendations now actively encourage the early introduction of peanut for the prevention of peanut allergy, and other countries/settings recommend the inclusion of potential common food allergens, including peanut and egg, in complementary feeding regimens commencing at approximately 6 months but not before 4 months of age. Further studies that explore the efficacy of oral tolerance induction to other common food allergens and that focus on optimal timing, duration, and adherence are required.

Single-cell profiling of peanut-responsive T cells in patients with peanut allergy reveals heterogeneous effector TH2 subsets

Abstract: Background The contribution of phenotypic variation of peanut-specific T cells to clinical allergy or tolerance to peanut is not well understood Objectives Our objective was to comprehensively phenotype peanut-specific T cells in the peripheral blood of subjects with and without peanut allergy (PA) Methods We obtained samples from patients with PA, including a cohort undergoing baseline peanut challenges for an immunotherapy trial (Consortium of Food Allergy Research [CoFAR] 6) Subjects were confirmed as having PA, or if they passed a 1-g peanut challenge, they were termed high-threshold subjects Healthy control (HC) subjects were also recruited Peanut-responsive T cells were identified based on CD154 expression after 6 to 18 hours of stimulation with peanut extract Cells were analyzed by using flow cytometry and single-cell RNA sequencing Results Patients with PA had tissue- and follicle-homing peanut-responsive CD4 + T cells with a heterogeneous pattern of T H 2 differentiation, whereas control subjects had undetectable T-cell responses to peanut The PA group had a delayed and IL-2–dependent upregulation of CD154 on cells expressing regulatory T (Treg) cell markers, which was absent in HC or high-threshold subjects Depletion of Treg cells enhanced cytokine production in HC subjects and patients with PA in vitro , but cytokines associated with highly differentiated T H 2 cells were more resistant to Treg cell suppression in patients with PA Analysis of gene expression by means of single-cell RNA sequencing identified T cells with highly correlated expression of IL4 , IL5 , IL9 , IL13 , and the IL-25 receptor IL17RB Conclusions These results demonstrate the presence of highly differentiated T H 2 cells producing T H 2-associated cytokines with functions beyond IgE class-switching in patients with PA A multifunctional T H 2 response was more evident than a Treg cell deficit among peanut-responsive T cells

Egg-specific IgE and basophil activation but not egg-specific T-cell counts correlate with phenotypes of clinical egg allergy.

Abstract: Background Egg allergy is phenotypically heterogeneous. A subset of patients with egg allergy can tolerate egg in an extensively heated form. Inclusion of baked egg (BE) into the diet accelerates resolution of egg allergy. Conversely, BE reactivity is associated with persistent disease. The immune basis of this clinical heterogeneity is unknown. Objectives We sought to study egg-specific antibody, basophil, and T-cell responses in children with reactivity or tolerance to BE. Methods All participants underwent double-blind, placebo-controlled challenges to BE, and those who tolerated BE were challenged with unheated egg white protein to confirm clinical egg reactivity. Laboratory studies included serum antibody measurements, basophil activation tests, and CD154-based detection of egg-responsive T cells by using flow cytometry. Results Of the 129 children studied, BE-reactive participants had significantly greater levels of egg-, ovalbumin-, and ovomucoid-specific IgE; lower ratios of egg-specific IgG 4 /IgE; and increased basophil activation in response to egg. Among all participants, CD154-based profiling revealed egg-responsive T cells producing IL-4 and IL-13 but little IL-10 or IFN-γ, as well as the presence of egg-responsive Foxp3 + CD25 + CD127 low regulatory T cells. Egg-responsive T cells expressed CCR4, CCR6, and CXCR5, indicating capacity for homing to the skin, mucosa, and B-cell follicles. However, neither the frequency nor phenotype of egg-responsive T cells was different in those with tolerance or reactivity to BE. Conclusions Egg-specific antibody and basophil responses, but not T-cell responses, are greater in those with reactivity versus tolerance to BE. Egg-specific antibody and T-cell responses were highly heterogeneous in this cohort. The clinical implications of this immune heterogeneity will need to be studied longitudinally.

Characterization of the B-cell receptor repertoires in peanut allergic subjects undergoing oral immunotherapy.

Abstract: B-cell receptors (BCRs) play a critical role in adaptive immunity as they generate highly diverse immunoglobulin repertoires to recognize a wide variety of antigens. To better understand immune responses, it is critically important to establish a quantitative and rapid method to analyze BCR repertoire comprehensively. Here, we developed "Bcrip", a novel approach to characterize BCR repertoire by sequencing millions of BCR cDNA using next-generation sequencer. Using this method and quantitative real-time PCR, we analyzed expression levels and repertoires of BCRs in a total of 17 peanut allergic subjects' peripheral blood samples before and after receiving oral immunotherapy (OIT) or placebo. By our methods, we successfully identified all of variable (V), joining (J), and constant (C) regions, in an average of 79.1% of total reads and 99.6% of these VJC-mapped reads contained the C region corresponding to the isotypes that we aimed to analyze. In the 17 peanut allergic subjects' peripheral blood samples, we observed an oligoclonal enrichment of certain immunoglobulin heavy chain alpha (IGHA) and IGH gamma (IGHG) clones (P = 0.034 and P = 0.027, respectively) in peanut allergic subjects after OIT. This newly developed BCR sequencing and analysis method can be applied to investigate B-cell repertoires in various research areas, including food allergies as well as autoimmune and infectious diseases.

Antibiotic Use After Removal of Penicillin Allergy Label

Abstract: D Vyles, A Chiu, J Routes. Pediatrics. 2018;141(5):e20173466 To evaluate the clinical and economic impact of negative penicillin testing results for children with a previous penicillin allergy label. This study included caregivers and primary care providers (PCPs) of 100 children between the ages of 4 and 18 years with negative test results for penicillin allergy after percutaneous, intracutaneous testing and an oral challenge. A follow-up case series investigation was performed on 100 children with “low-risk” allergy symptoms who had a negative penicillin allergy evaluation result. Low-risk symptoms included a nonurticarial rash, itching, diarrhea, and vomiting. The study authors hypothesized that no serious allergic reactions would occur with reexposure and that prescribing practices would change as a result of testing. A brief telephone survey was administered to parents and PCPs. Parents were questioned regarding antibiotic use since penicillin testing, any recent allergic reactions, parental comfort level with future penicillin use, …

Peptide and Recombinant Allergen Vaccines for Food Allergy

Abstract: Food allergy is a significant public health problem, with no suitable treatments available for patients. Currently, patients are limited to avoidance and the use of readily available emergency medications. Immunotherapy is an appealing therapeutic strategy for inducing tolerance. Studies with whole native allergens have demonstrated the efficacy of immunotherapy for food allergy; however, the risk of IgE-mediated reactions with such treatment is significant. Advances in molecular biology techniques, including purification, sequencing, and cloning, have allowed researchers to identify specific allergen components and T cell binding epitopes. Support for the use of recombinant and peptide vaccines for food allergy comes from prior studies involving aeroallergens and hymenoptera venom. By manipulating allergen structure and IgE binding, allergenicity can be reduced, thereby reducing systemic reactions, making recombinant and peptide vaccines a safe and effective form of immunotherapy. Pre-clinical studies using in vitro and murine models demonstrated a more tolerant state following the use of these therapies. Studies with human subjects will be necessary to characterize the effects of recombinant and peptide food allergy vaccines and to demonstrate a safe treatment option for patients.

Adjuvanted Immunotherapy Approaches for Peanut Allergy.

Abstract: Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.