Standardizing Randomized Controlled Trials in Celiac Disease: An International Multidisciplinary Appropriateness Study

Beyond gluten-free diet: a critical perspective on phase 2 trials on non-dietary pharmacological therapies for coeliac disease

Coeliac disease is an immune-mediated chronic enteropathy, with a prevalence of around 1% in the general population and occurring in genetically susceptible individuals after the ingestion of gluten proteins present in wheat, rye and barley. Currently, a strict lifelong gluten-free diet is the cornerstone of treatment of coeliac disease. However, maintaining strict dietary adherence is challenging for many patients, due to the high costs, the highly restrictive nature of the diet and the impact on patients' quality of life. Moreover, a tiny minority of coeliac patients can develop pre-malignant/malignant complications of coeliac disease, a group of conditions, that despite being rare, are still burdened by a poor prognosis due to the lack of effective therapies. Therefore, the development of pharmacological treatments as an alternative to or supportive of a gluten-free diet is still an unmet need. The identification of new pathogenetic targets in the last years has enabled the development of several candidates molecules, many of which have been investigated in phase 2/3 clinical trials. In this narrative review we aim to summarise the investigational therapies that have been evaluated in phase 2/3 trials and provide a critical overview on the latest advances in this field.

Celiac disease and nonceliac enteropathies

PURPOSE OF REVIEW

This review highlights recent research in the field of celiac disease.

RECENT FINDINGS

Epidemiological studies continue to identify celiac disease-associated diseases such as inflammatory arthritis, irritable bowel syndrome, and cardiovascular disease. Recently published consensus guidelines provide recommendations for the long-term management and monitoring of patients with celiac disease. There are multiple pharmaceutical therapies for celiac disease under investigation, and recent phase I and phase II trials are reviewed here. Finally, a recent trial of patients with nonceliac gluten sensitivity demonstrates a significant nocebo effect in this condition.

SUMMARY

Recent advances in celiac disease include the development of new clinical guidelines as well as promising new therapeutics. Continued high-quality research is needed to improve the outcomes of patients with celiac disease and nonceliac enteropathies.

Food-Based Interventions as Therapy for Inflammatory Bowel Disease: Important Steps in Diet Trial Design and Reporting of Outcomes

Diet therapy for inflammatory bowel disease (IBD) is an international research priority but guidance for IBD-specific diet trial design is lacking. This review critically evaluates key elements of prospective IBD food-based intervention trials and identifies gaps. Electronic databases were searched for interventional IBD diet studies. Prospective primary studies/trials were included if used food-based dietary strategies. Forty studies/trials evaluating 29 food-based strategies as therapy for IBD were identified. Considerable heterogeneity in diets, trial design, and methodology exists. Thirty-one trials (78%) intended the diet to modulate inflammation but 14/31 (46%) did not have a primary endpoint measuring an objective change in inflammatory activity and 20/31 (65%) controlled for medication stability prior to application of diet at baseline. Higher-quality IBD diet trials used symptom-based assessment tools coupled with an objective evaluation of inflammatory activity. Dietary advice trials are the most common. One-third of trials developed and administered diet education without a dietitian. Evaluation and reporting on adherence to diet therapy occurred in <60% of trials. Failure to include or report on key elements of trial design reduced the interpretability and validity of the results. This is a considerable limitation to advancing scientific knowledge in this area. Diet therapy trials should adhere to similar rigorous quality standards used to develop other IBD therapies. Therefore, a set of practical recommendations was generated to provide the authors' perspective to help inform the future design of high-quality IBD diet trials.

Digesting gluten with oral endopeptidases to improve the management of celiac disease

In our editorial, we want to comment on the article by Stefanolo et al titled "Effect of Aspergillus niger prolyl endopeptidase in patients with celiac disease on a long-term gluten-free diet". Celiac disease is an immune-mediated disorder triggered by dietary gluten in genetically predisposed individuals. Although avoiding gluten can permit patients to live symptom-free, ongoing voluntary or involuntary exposure to gluten is common and associated with persistent villous atrophy in small bowel mucosa. As villous atrophy predisposes patients to life threatening complications, such as osteoporotic fractures or malignancies, therapeutic adjuncts to gluten-free diet become important to improve patients' quality of life and, if these adjuncts can be shown to improve villous atrophy, avoid complications. Oral administration of enzyme preparations, such as endopeptidases that digest gluten and mitigate its antigenicity to trigger inflammation, is one clinical strategy under investigation. The article is about the utility of one endopeptidase isolated from Aspergillus niger. We critique findings of this clinical trial and also summarize endopeptidase-based as well as other strategies and how they can complement gluten-free diet in the management of celiac disease.

Evolution in coeliac disease diagnosis and management

The traditional gut-centric view of coeliac disease is evolving as immune and genetic insights underscore the central importance of a systemic, T cell immune response to gluten in disease pathogenesis. As the field increasingly recognize the limitations of small intestinal histology as the diagnostic standard, data supporting the accuracy of an immune (serologic) diagnosis of coeliac disease - well demonstrated in children - are growing for adults. Novel biomarkers such as interleukin-2 that identify the gluten-specific T cell demonstrate high sensitivity and specificity for coeliac disease and offer the potential for a diagnostic approach that avoids the need for gluten challenge. Asymptomatic disease and manifestations outside the gut pose considerable challenges for diagnosis using a case-finding strategy and enthusiasm for population screening is growing. The gluten-free diet remains a highly restrictive treatment and there is a paucity of controlled data to inform a safe gluten intake threshold. Ongoing symptoms and enteropathy are common and require systematic evaluation. Slowly-responsive disease is prevalent in the older patient diagnosed with coeliac disease, and super-sensitivity to gluten is an emerging concept that may explain many cases of nonresponsive disease. While there is great interest in developing novel therapies for coeliac disease, no drug has yet been registered. Efficacy studies are generally assessing drugs in patients with treated coeliac disease who undergo gluten challenge or in patients with nonresponsive disease; however, substantial questions remain around specific endpoints relevant for patients, clinicians and regulatory agencies and optimal trial design. Novel immune tools are providing informative readouts for clinical trials and are now shaping their design.

Celiac disease: Hope for new treatments beyond a gluten-free diet

BACKGROUND & AIMS

Celiac disease (CD) is a chronic inflammatory disease of the small intestine induced and maintained by gluten ingestion in susceptible individuals. Current treatment consists of strict adherence to a lifelong gluten-free diet (GFD) which is considered safe and effective in the large majority of patients. However, since adherence to a GFD is difficult and has a negative impact on quality of life, an increasing interest in other treatment options has emerged. Moreover, in some individuals a GFD is not sufficiently effective, necessitating alternative treatments.

METHODS

By performing a systematic search, we constructed a detailed narrative review. Only treatment options considered relevant and conducted in a phase I, II or III clinical trial were included.

RESULTS

Based on the pathophysiology of CD, four major therapeutic approaches can be distinguished: firstly, by focusing on intraluminal gluten detoxification before absorption occurs, secondly, by modulating intestinal permeability and preventing paracellular uptake, thirdly, by enhancing immunological tolerance to gluten and finally, by regulating gluten auto-immunity.

CONCLUSIONS

Despite significant efforts, no treatment has yet completed a phase III clinical trial. Future studies will likely focus on the use of supplemental drugs in conjunction to a GFD, with ALV003 and ZED-1227 currently being the most promising therapeutic options.

Tolerance-inducing therapies in coeliac disease - mechanisms, progress and future directions

Coeliac disease is an autoinflammatory condition caused by immune reactions to cereal gluten proteins. Currently, the only available treatment for the condition is a lifelong avoidance of gluten proteins in the diet. There is an unmet need for alternative therapies. Coeliac disease has a strong association with certain HLA-DQ allotypes (DQ2.5, DQ2.2 and DQ8), and these disease-associated HLA-DQ molecules present deamidated gluten peptides to gluten-specific CD4+ T cells. The gluten-specific CD4+ T cells are the drivers of the immune reactions leading to coeliac disease. Once established, the clonotypes of gluten-specific CD4+ T cells persist for decades, explaining why patients must adhere to a gluten-free diet for life. Given the key pathogenic role of gluten-specific CD4+ T cells, tolerance-inducing therapies that target these T cells are attractive for treatment of the disorder. Lessons learned from coeliac disease might provide clues for treatment of other HLA-associated diseases for which the disease-driving antigens are unknown. Thus, intensive efforts have been and are currently implemented to bring an effective tolerance-inducing therapy for coeliac disease. This Review discusses mechanisms of the various approaches taken, summarizing the progress made, and highlights future directions in this field.