Background: It is unclear how far the superior efficacy of omalizumab, established in randomized controlled clinical trials of patients with severe allergic asthma (SAA), translates into routine practice and when compared to matched controls. Methods: New-onset omalizumab-treated (OT) patients with SAA (n = 53) were compared to a matched control group of usual-care (UC) patients (n = 53). Treatment and procedures were naturalistic. Subsequent to a baseline assessment, patients were followed up over at least 6 months with at least two follow-up assessments. Primary clinical outcomes were the number of asthma attacks, persistence of asthma symptoms and degree of control [asthma control test (ACT), Global Initiative for Asthma]. Secondary outcome criteria were quality of life (Euro-Qol 5D) and number of medications. For each outcome we compared within-group effects from baseline to 6-month follow-up as well as between-group effects. Results: OT patients showed significant improvements in number [effect size (ES) = 0.03] and frequency (ES = 0.04) of asthma attacks as well as asthma control (ES = 0.09), whereas controls revealed no significant improvements in these measures. Further improvements in the OT group were found for ‘perceived control always’ (ACT, p = 0.006), no impairment (ACT, p = 0.02), reduction of sickness days (p = 0.002) and number of medications needed (p = 0.001). Conclusions: Substantial beneficial effects of omalizumab, similar to those observed in controlled trials and after marketing studies, were confirmed, particularly with regard to the reduction of asthma attacks, persistence of symptoms, asthma control and reduction of concomitant asthma medications. This study provides a tougher test and generalizable evidence for the effectiveness of omalizumab in routine care.

Background: It is unclear how far the superior efficacy of omalizumab, established in randomized controlled clinical trials of patients with severe allergic asthma (SAA), translates into routine practice and when compared to matched controls. Methods: New-onset omalizumab-treated (OT) patients with SAA (n = 53) were compared to a matched control group of usual-care (UC) patients (n = 53). Treatment and procedures were naturalistic. Subsequent to a baseline assessment, patients were followed up over at least 6 months with at least two follow-up assessments. Primary clinical outcomes were the number of asthma attacks, persistence of asthma symptoms and degree of control [asthma control test (ACT), Global Initiative for Asthma]. Secondary outcome criteria were quality of life (Euro-Qol 5D) and number of medications. For each outcome we compared within-group effects from baseline to 6-month follow-up as well as between-group effects. Results: OT patients showed significant improvements in number [effect size (ES) = 0.03] and frequency (ES = 0.04) of asthma attacks as well as asthma control (ES = 0.09), whereas controls revealed no significant improvements in these measures. Further improvements in the OT group were found for ‘perceived control always’ (ACT, p = 0.006), no impairment (ACT, p = 0.02), reduction of sickness days (p = 0.002) and number of medications needed (p = 0.001). Conclusions: Substantial beneficial effects of omalizumab, similar to those observed in controlled trials and after marketing studies, were confirmed, particularly with regard to the reduction of asthma attacks, persistence of symptoms, asthma control and reduction of concomitant asthma medications. This study provides a tougher test and generalizable evidence for the effectiveness of omalizumab in routine care.

Chronic spontaneous urticaria (CSU) is defined as itchy hives with or without angioedema with a burning sensation that last for six weeks or longer and have no apparent external trigger. The disease occurs in about 1 % of the population. The itching and burning symptoms affect the patient’s quality of life in a negative way which makes a treatment highly needed. The first-line medication for the treatment of CSU is non-sedating H1-antihistamines in recommended doses and the second line of treatment is an increased dose of H1-antihistamines, up to four-fold the approved doses. However, many patients do not response to these therapies whereas a third-line treatment, an add-on therapy with omalizumab, is necessary. Omalizumab is a monoclonal anti-IgE-antibody that binds to free IgE and prevents them to attach to FcεRI-receptors on inflammatory cells like mast cells. This leads to a lower activation of mast cells and less histamine gets released. The definite mechanism of action of CSU-symptoms relief is still unclear but it is thought to be due to decreased levels of IgE and FcεRI-receptors. The symptoms of CSU can be scored using weekly itch severity score (ISS7) which scores the pruritus, weekly hive severity score (HSS7) which scores the number of hives and weekly urticaria activity score (UAS7) that scores both pruritus and number of hives together. The aim of this literature review was to evaluate the efficacy and safety of omalizumab in patients diagnosed with CSU. A search on PubMed was conducted with the search terms "omalizumab" AND "chronic spontaneous urticaria" and "omalizumab" AND "chronic idiopathic urticaria". The articles were limited to randomized, controlled and double-blinded trials that were published 2010 or later. A total of five studies were included for further analysis; MYSTIQUE, ASTERIA II, ASTERIA I, POLARIS and GLACIAL. The studies showed that omalizumab 300 mg and 150 mg reduced the symptoms of CSU significantly compared with placebo, whereas 300 mg had the best efficacy in decreasing the values of ISS7, HSS7 and UAS7. The patients went from having severe urticaria to mild urticaria after treatment with omalizumab. The degree of itching improved from severe itching to mild itching. The side effects were mild to moderate, the most common were nasopharyngitis, headache, arthralgia and upper respiratory tract infection. Omalizumab showed to be effective and safe as an add-on therapy for the treatment of patients with chronic spontaneous urticaria who did not respond adequately to treatment with H1-antihistamines.

La prévalence des allergies alimentaires IgE-médiées aurait triplé au cours de la dernière décennie avec des études Nord-Américaines atteignant les 8% chez les enfants. Quoiqu’il n’y ait à ce jour aucun traitement curatif pour les allergies alimentaires, l’immunothérapie oral (OIT) constitue une nouvelle approche expérimentale prometteuse. Cette dernière consiste en l’administration de doses progressive d’allergènes par voie orale sur une période prolongée dans le but d’instaurer un état de désensibilisation et possiblement une tolérance orale soutenue. Cette approche a été démontrée sécuritaire et permettrait la désensibilisation à haute dose de plus de 80% des participants allergiques aux arachides, lait ou œufs. Dans cette thèse, nous présentons 2 études de phase 1 portant sur des protocoles d’OIT, destinés à optimiser l’efficience du traitement chez les sujets avec allergies alimentaires multiples. Près de 30% des enfants avec allergie alimentaire sont allergiques à plus d’un aliment, une proportion qui augmente à 70% lorsqu’on considère les cas les plus sévères. Ces enfants sont à risque augmenté de réactions accidentelles et souffrent d’un impact plus grand sur leur qualité de vie. Dans la première étude, en créant un mélange individualisé avec un ratio stochiométrique 1:1 entre les protéines des aliments allergiques de l’enfant, nous démontrons qu’il est possible de désensibiliser jusqu’à 5 aliments simultanément avec un profil d’innocuité similaire à une monothérapie. Dans la seconde étude, nous utilisons un traitement à l’omalizumab, un anticorps monoclonal anti-IgE, pour permettre une désensibilisation orale multi-allergénique fortement accélérée. Lorsque comparé à l’approche sans omalizumab, ce protocole s’associe à une nette diminution du temps requis pour atteindre les doses d’entretien, passant d’une médiane de 21 à 4 mois, sans affecter le profil d’innocuité. Alors que ces études fournissent des approches cliniques raisonnables pour désensibiliser la population multi-allergique, plusieurs questions persistent, notamment en ce qui a trait à l’induction de tolérance permanente. Une barrière majeure à cet égard réside dans notre piètre compréhension des mécanismes sous-jacents à l’immunothérapie. Prenant avantage d’échantillons cliniques bien caractérisés provenant des essais cliniques ci-haut mentionnés, nous utilisons les nouvelles technologies de séquençage TCR pour suivre la distribution clonale des lymphocytes T spécifiques aux arachides durant une immunothérapie orale. Nous démontrons que l’OIT s’associe à des changements significatifs dans les fréquences des clones spécifiques, suggérant un processus d’épuisement clonal et de remplacement. Nous démontrons par ailleurs que le test de prolifération lymphocytaire, traditionnellement utilisé pour évaluer la réponse cellulaire allergique, est dominé par une distribution polyclonale hautement non-spécifique. Cette observation a des implications majeures considérant que la plupart de la littérature actuelle sur la réponse T se base sur cette technique. En somme, cette thèse jette les bases pour des programmes de recherche translationnelle pour optimiser et personnaliser les protocoles cliniques actuels et développer de nouvelles avenues d’investigation et de traitement pour améliorer la prise en charge des sujets avec allergies alimentaires. / The prevalence of IgE-mediated food allergies has tripled over the last decade with prospective studies indicating that up to 8% of children may be affected in North America. There is currently no cure for food allergy but oral immunotherapy (OIT) is an experimental approach to treat food allergies. It consists in the progressive administration from minute to large amounts of the allergenic food by the mouth over a prolonged period of time to induce a state of desensitization and possibly sustained tolerance. This approach has been shown to be safe and to allow desensitization to high doses in over 80% of participants allergic to peanuts, milk or egg. In this thesis, we present two phase 1 trials on OIT protocols designed to efficiently treat multiple foods allergies. About 30% of children with food allergy are allergic to more than one food. This proportion increases to 70% when considering the most severe cases. Children with multiple food allergies are at higher risk of accidental reactions and suffer from greater impact on quality of life than those with single food allergies. By creating a customized treatment mix with a 1:1 stoichiometric ratio for the child’s relevant food proteins, we were first able to safely desensitize up to 5 foods simultaneously with a safety profile similar to single allergen therapy and a minimal increase in time to maintenance. Then, taking advantage of recent evidence showing that omalizumab, an anti-IgE receptor monoclonal antibody, can significantly raise reaction thresholds in food allergic subjects, we used short courses of omalizumab to allow very rapid oral desensitization to various foods in a second phase 1 study. When compared to “standard” multi-OIT, the omalizumab-enabled rush protocol resulted in a decreased time to maintenance from a median of 21 to 4 months. While these studies provide reasonable clinical approaches to this population, many questions remain, especially with regards to long term tolerance. A major limit to our progress in improving these protocols stems from our lack of understanding of the underlying immune mechanisms of oral immunotherapy. Taking advantage of well phenotyped samples from the afore-mentioned trials, we used next-generation high-throughput TCR sequencing to follow clonal distribution of peanut specific T cells during oral immunotherapy. We found that OIT is associated with significant changes in food-specific clonal frequencies, suggesting clonal exhaustion and replacement as an underlying mechanism of OIT. In addition, we show that the proliferation assay which is traditionally used to assess the cellular response is dominated by a highly non-specific polyclonal distribution. This observation has important implications considering most of the current literature on T cell response to immunotherapy is based on this assay. This highlights the need for the development of new tools to assess the cellular allergic response. Overall this thesis lays the ground for further comprehensive translational research programs on the treatment of food allergy.