IMPORTANCE Pediatric-onset Crohn disease is more aggressive than adult-onset disease, has high rates of resistance to existing drugs, and can lead to permanent impairments. Few trials have evaluated new drugs for refractory Crohn disease in children.OBJECTIVE To determine whether thalidomide is effective in inducing remission in refractory pediatric Crohn disease. DESIGN, SETTING, AND PATIENTS Multicenter, double-blind, placebo-controlled, randomized clinical trial of 56 children with active Crohn disease despite immunosuppressive treatment, conducted August 2008-September 2012 in 6 pediatric tertiary care centers in Italy. INTERVENTIONS Thalidomide, 1.5 to 2.5 mg/kg per day, or placebo once daily for 8 weeks. In an open-label extension, nonresponders to placebo received thalidomide for an additional 8 weeks. All responders continued to receive thalidomide for an additional minimum 52 weeks. MAIN OUTCOMES AND MEASURES Primary outcomes were clinical remission at week 8, measured by Pediatric Crohn Disease Activity Index (PCDAI) score and reduction in PCDAI by Ն25% or Ն75% at weeks 4 and 8. Primary outcomes during the open-label follow-up were clinical remission and 75% response. RESULTS Twenty-eight children were randomized to thalidomide and 26 to placebo. Clinical remission was achieved by significantly more children treated with thalidomide (13/28 [46.4%] vs 3/26 [11.5%]; risk ratio [RR], 4.0 [95% CI, 1.2-12.5]; P = .01; number needed to treat [NNT], 2.86). Responses were not different at 4 weeks, but greater improvement was observed at 8 weeks in the thalidomide group (75% response, 13/28 [46.4%] vs 3/26 [11.5%]; RR, 4.0 [95% CI, 1.2-12.5]; NNT = 2.86; P = .01; and 25% response, 18/28 [64.2%] vs 8/26 [30.8%]; RR, 2.1 [95% CI,]; NNT = 2.99; P = .01). Of the nonresponders to placebo who began receiving thalidomide, 11 of 21 (52.4%) subsequently reached remission at week 8 (RR, 4.5 [95% CI, 1.4-14.1]; NNT = 2.45; P = .01). Overall, 31 of 49 children treated with thalidomide (63.3%) achieved clinical remission, and 32 of 49 (65.3%) achieved 75% response. Mean duration of clinical remission in the thalidomide group was 181.1 weeks (95% CI, 144.53-217.76) vs 6.3 weeks (95% CI, 3.51-9.15) in the placebo group (P < .001). Cumulative incidence of severe adverse events was 2.1 per 1000 patient-weeks, with peripheral neuropathy the most frequent severe adverse event.CONCLUSIONS AND RELEVANCE In children and adolescents with refractory Crohn disease, thalidomide compared with placebo resulted in improved clinical remission at 8 weeks of treatment and longer-term maintenance of remission in an open-label follow-up. These findings require replication to definitively determine clinical utility of this treatment.

Natural and synthetic glucocorticoids (GCs) are widely employed in a number of inflammatory, autoimmune and neoplastic diseases, and, despite the introduction of novel therapies, remain the first-line treatment for inducing remission in moderate to severe active Crohn's disease and ulcerative colitis. Despite their extensive therapeutic use and the proven effectiveness, considerable clinical evidence of wide inter-individual differences in GC efficacy among patients has been reported, in particular when these agents are used in inflammatory diseases. In recent years, a detailed knowledge of the GC mechanism of action and of the genetic variants affecting GC activity at the molecular level has arisen from several studies. GCs interact with their cytoplasmic receptor, and are able to repress inflammatory gene expression through several distinct mechanisms. The glucocorticoid receptor (GR) is therefore crucial for the effects of these agents: mutations in the GR gene (NR3C1, nuclear receptor subfamily 3, group C, member 1) are the primary cause of a rare, inherited form of GC resistance; in addition, several polymorphisms of this gene have been described and associated with GC response and toxicity. However, the GR is not self-standing in the cell and the receptor-mediated functions are the result of a complex interplay of GR and many other cellular partners. The latter comprise several chaperonins of the large cooperative hetero-oligomeric complex that binds the hormone-free GR in the cytosol, and several factors involved in the transcriptional machinery and chromatin remodeling, that are critical for the hormonal control of target genes transcription in the nucleus. Furthermore, variants in the principal effectors of GCs (e.g. cytokines and their regulators) have also to be taken into account for a comprehensive evaluation of the variability in GC response. Polymorphisms in genes involved in the transport and/or metabolism of these hormones have also been suggested as other possible candidates of interest that could play a role in the observed inter-individual differences in efficacy and toxicity. The best-characterized example is the drug efflux pump P-glycoprotein, a membrane transporter that extrudes GCs from cells, thereby lowering their intracellular concentration. This protein is encoded by the ABCB1/MDR1 gene; this gene presents different known polymorphic sites that can influence its expression and function. This editorial reviews the current knowledge on this topic and underlines the role of genetics in predicting GC clinical response. The ambitious goal of pharmacogenomic studies is to adapt therapies to a patient's specific genetic background, thus improving on efficacy and safety rates.

These results confirm that genetic and demographic factors may affect the response to GCs in young patients with IBD and strengthen the importance of studying high-order interactions for predicting response.

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Glucocorticoids (GCs) exert their effects through regulation of gene expression after activation in the cytoplasm of the glucocorticoid receptor (GR) encoded by NR3C1 gene. A negative feedback mechanism resulting in GR autoregulation has been demonstrated through the binding of the activated receptor to intragenic sequences called GRE-like elements, contained in GR gene. The long noncoding RNA growth arrest-specific transcript 5 (GAS5) interacts with the activated GR suppressing its transcriptional activity. The aim of this study was to evaluate the possible role of GAS5 and NR3C1 gene expression in the antiproliferative effect of methylprednisolone in peripheral blood mononuclear cells and to correlate the expression with individual sensitivity to GCs. Subjects being poor responders to GCs presented higher levels of GAS5 and NR3C1 in comparison with good responders. We suggest that abnormal levels of GAS5 may alter GC effectiveness, probably interfering with the mechanism of GR autoregulation.

Azathioprine is a purine antimetabolite drug commonly used to treat inflammatory bowel disease (IBD). In vivo it is active after reaction with reduced glutathione (GSH) and conversion to mercaptopurine. Although this reaction may occur spontaneously, the presence of isoforms M and A of the enzyme glutathione-S-transferase (GST) may increase its speed. Indeed, in pediatric patients with IBD, deletion of GST-M1, which determines reduced enzymatic activity, was recently associated with reduced sensitivity to azathioprine and reduced production of azathioprine active metabolites. In addition to increase the activation of azathioprine to mercaptopurine, GSTs may contribute to azathioprine effects even by modulating GSH consumption, oxidative stress and apoptosis. Therefore, genetic polymorphisms in genes for GSTs may be useful to predict response to azathioprine even if more in vitro and clinical validation studies are needed.

In this pilot randomized controlled trial on cases of UC refractory to immunosuppressive therapy, thalidomide compared with placebo resulted in improved clinical remission at 8 weeks of treatment and in longer term maintenance of remission. These findings require replication in larger clinical studies evaluating both thalidomide efficacy and safety.

This study describes the effect of candidate genetic polymorphisms in TPMT, ITPA, and GST-M1 on azathioprine pharmacokinetics in IBD patients, showing, for the first time, relevant effects of GST-M1 genotype on azathioprine metabolites concentration.