Withdrawal of thiopurines in Crohn's disease treated with scheduled adalimumab maintenance: a prospective randomised clinical trial (DIAMOND2)

Systematic review and bayesian network meta-analysis: comparative efficacy and safety of six commonly used biologic therapies for moderate-to-severe Crohn's disease

Background

In contrast to previous network meta-analysis using classical frequentist methods, we evaluated the efficacy and safety of six frequently-used biologics through a Bayesian method.

Methods

Web of Science, Scopus, CENTRAL, ClinicalTrials.gov and ICTRP were searched to collect randomized controlled trials (RCTs) in adults with moderate-to-severe Crohn's disease, comparing Infliximab, Adalimumab, Certolizumab pegol, Ustekinumab, Risankizumab, or Vedolizumab, relative to placebo or an active comparator for induction of clinical response (two different definitions) and maintenance of clinical remission. A random-effects model was performed with rankings according to the surface under cumulative ranking curve (SUCRA) probability. Finally, we completed sensitivity and consistency analyses, and evaluated the certainty of evidence through GRADE working group guidance.

Results

We identified 22 and 20 RCTs for induction and maintenance therapy, respectively. Infliximab combined with azathioprine was most effective for inducing clinical response in TNF (tumor necrosis factor) antagonist-naïve patients. For TNF antagonist-experienced patients, Ustekinumab (SUCRA 86.19) and Risankizumab (SUCRA 62.56) have the largest SUCRA in induction of clinical response. Risankizumab has the lowest risk of adverse events (SUCRA 84.81), serious adverse events (SUCRA 94.23), and serious infections (SUCRA 79.73) in induction therapy. Adalimumab and the 10 mg/kg regimen of Infliximab rank highest for maintaining clinical remission.

Conclusion

This analysis suggests that Infliximab in combination with azathioprine may be preferred biologic agents for induction therapy in TNF antagonist-naïve patients. For TNF antagonist-experienced patients, Ustekinumab and Risankizumab may be preferred biologic agents for induction therapy. Risankizumab potentially has the lowest safety risk worth exploring in induction therapy. Adalimumab and the 10 mg/kg regimen of Infliximab have maintenance efficacy benefits for responders to induction therapy.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=458609, Identifier CRD42023458609.

Combination treatment of inflammatory bowel disease: Present status and future perspectives

The treatment of patients with inflammatory bowel disease (IBD), especially those with severe or refractory disease, represents an important challenge for the clinical gastroenterologist. It seems to be no exaggeration to say that in these patients, not only the scientific background of the gastroenterologist is tested, but also the abundance of "gifts" that he should possess (insight, intuition, determination, ability to take initiative, etc.) for the successful outcome of the treatment. In daily clinical practice, depending on the severity of the attack, IBD is treated with one or a combination of two or more pharmaceutical agents. These combinations include not only the first-line drugs (e.g., mesalazine, corticosteroids, antibiotics, etc) but also second- and third-line drugs (immunosuppressants and biologic agents). It is a fact that despite the significant therapeutic advances there is still a significant percentage of patients who do not satisfactorily respond to the treatment applied. Therefore, a part of these patients are going to surgery. In recent years, several small-size clinical studies, reviews, and case reports have been published combining not only biological agents with other drugs (e.g., immunosuppressants or corticosteroids) but also the combination of two biological agents simultaneously, especially in severe cases. In our opinion, it is at least a strange (and largely unexplained) fact that we often use combinations of drugs in a given patient although studies comparing the simultaneous administration of two or more drugs with monotherapy are very few. As mentioned above, there is a timid tendency in the literature to combine two biological agents in severe cases unresponsive to the applied treatment or patients with severe extraintestinal manifestations. The appropriate dosage, the duration of the administration, the suitable timing for checking the clinical and laboratory outcome, as well as the treatment side-effects, should be the subject of intense clinical research shortly. In this editorial, we attempt to summarize the existing data regarding the already applied combination therapies and to humbly formulate thoughts and suggestions for the future application of the combination treatment of biological agents in a well-defined category of patients. We suggest that the application of biomarkers and artificial intelligence could help in establishing new forms of treatment using the available modern drugs in patients with IBD resistant to treatment.

Withdrawal of Immunomodulators or TNF Antagonists in Patients With Inflammatory Bowel Diseases in Remission on Combination Therapy: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Withdrawal of immunomodulators (IMMs) or tumor necrosis factor (TNF) antagonists in patients with inflammatory bowel diseases (IBDs) in remission on combination therapy is attractive. We evaluated the efficacy and safety of (1) IMM, or (2) TNF antagonist withdrawal in patients with IBD in sustained remission on combination therapy.

METHODS

Through a systematic review till March 31, 2023, we identified randomized controlled trials (RCTs) that compared the efficacy and safety of IMM or TNF antagonist withdrawal vs continued combination therapy, in patients with IBD in sustained corticosteroid-free clinical remission for >6 months on combination therapy. Primary outcome was risk of relapse and serious adverse events at 12 months. We conducted meta-analysis to calculate relative risk (RR) and 95% confidence interval (CI) and used Grading of Recommendations Assessment, Development and Evaluation (GRADE) to appraise certainty of evidence.

RESULTS

We identified 8 RCTs with 733 patients (77% with Crohn's disease, 91% on infliximab-based combination therapy). On meta-analysis of 5 RCTs, there was no difference in the risk of relapse between patients with IMM withdrawal (continued TNF antagonist monotherapy) vs continued combination therapy (16.8% vs 14.9%; RR, 1.15; 95% CI, 0.75-1.76) without heterogeneity (low certainty of evidence). TNF antagonist withdrawal (continued IMM monotherapy) was associated with 2.4-times higher risk of relapse compared with continuing combination therapy (31.5% vs 11.2%; RR, 2.35; 95% CI, 1.38-4.01), with minimal heterogeneity (low certainty of evidence). There was no difference in the risk of serious adverse events with IMM or TNF antagonist withdrawal vs continued combination therapy.

CONCLUSIONS

In patients with IBD in sustained corticosteroid-free clinical remission for >6 months on combination therapy, de-escalation with TNF antagonist withdrawal, but not IMM withdrawal, was associated with an increased risk of relapse.

A Systematic Review on Long-Term Efficacy Outcome Measures in Crohn's Disease Patients

BACKGROUND

The traditional long-term treatment goal of Crohn's disease [CD] is maintenance of corticosteroid-free clinical remission. Additional treatment targets, such as biochemical, endoscopic and patient-reported remission, are advocated. The relapsing-remitting nature of CD provides a challenge to the timing of target assessment. Cross-sectional assessment at predetermined moments disregards the health state in between measurements. In this systematic review, we provide an overview of outcomes used to assess long-term efficacy in clinical trials in CD.

METHODS

A systematic search of the PubMed and EMBASE databases was performed to identify clinical trials in luminal CD reporting on maintenance treatment [strategies] since 1995. Two independent reviewers selected eligible articles for full text retrieval, and assessed if long-term corticosteroid-free clinical, biochemical, endoscopic or patient-reported efficacy outcomes were used.

RESULTS

The search resulted in 2452 hits and 82 articles were included. Clinical activity was used in 80 studies [98%] as the long-term efficacy outcome, and in 21 [26%] of these concomitant corticosteroid use was taken into account. C-reactive protein was used in 32 studies [41%], faecal calprotectin in 15 studies [18%], endoscopic activity in 34 studies [41%] and patient-reported outcome in 32 studies [39%]. In seven studies, clinical, biochemical, endoscopic activity and the patient's perspective were measured. In most studies cross-sectional measures or multiple measurements over time were used.

CONCLUSION

In none of the published clinical trials in CD was sustained remission on all treatment targets reported. Cross-sectional outcomes at predetermined times were widely applied, leading to lack of information regarding sustained corticosteroid-free remission for this relapsing-remitting chronic disease.

Use of biologics for the management of Crohn's disease: IG-IBD technical review based on the GRADE methodology

The therapeutic armamentarium for the management of Crohn's disease (CD) is rapidly expanding. Several biologic therapies (e.g. infliximab, adalimumab, vedolizumab, and ustekinumab) have been regulatory approved, and there is considerable practice variability in the treatment of patients with CD. This technical review systematically searched and identified the current evidence, synthesized it using meta-analytic methodology, appraised its quality, and concisely presented it, thus forming the basis for developing clinical practice recommendations on the use of biologic treatments in adult patients with CD.

De-escalation of Therapy in Patients with Quiescent Inflammatory Bowel Disease

Inflammatory bowel disease is a chronic disease of unknown origin that requires long-term treatment. The optical duration of maintenance treatment once remission has been achieved remains unclear. When discussing a de-escalation strategy, not only the likelihood of relapse but also, the outcome of retreatment for relapse after de-escalation should be considered. Previous evidence has demonstrated controversial results for risk factors for relapse after de-escalation due to the various definitions of remission and relapse. In fact, endoscopic or histologic remission has been suggested as a treatment target; however, it might not always be indicative of a successful drug withdrawal. For better risk stratification of relapse after de-escalation, it may be necessary to evaluate both the current and previous treatments. Following de-escalation, biomarkers should be closely monitored. In addition to the risk of relapse, a comprehensive understanding of the overall outcome, such as the long-term safety, patient quality of life, and impact on healthcare costs, is necessary. Therefore, a shared decision-making with patients on a case-by-case basis is imperative.

Treatment escalation and de-escalation decisions in Crohn's disease: Delphi consensus recommendations from Japan, 2021

BACKGROUND

We aimed to develop criteria for treatment intensification in patients with (1) luminal Crohn's disease (CD), (2) CD with perianal disease and/or fistula, (3) CD with small bowel stenosis, (4) in the postoperative setting, and (5) for discontinuing or reducing the dose of treatment in patients with CD.

METHODS

PubMed and Embase were searched for studies published since 1998 which may be relevant to the five defined topics. Results were assessed for relevant studies, with preference given to data from randomized, controlled studies. For each question, a core panel of 12 gastroenterologists defined the treatment target and developed statements, based on the literature, current guidelines, and relevant additional studies. The evidence supporting each statement was graded using the Oxford Centre for Evidence-Based Medicine: Levels of Evidence (March 2009). A modified Delphi process was used to refine statements and gain agreement from 54 Japanese specialists at in-person and online meetings conducted between October 2020 and April 2021.

RESULTS

Seventeen statements were developed for treatment intensification in luminal CD (targeting endoscopic remission), six statements for treatment intensification in perianal/fistulizing CD (targeting healing of perianal lesions and complete closure of the fistula), six statements for treatment intensification in CD with small bowel stenosis (targeting resolution of obstructive symptoms), seven statements for treatment intensification after surgery (targeting endoscopic remission), and five statements for discontinuing or reducing the dose of treatment in patients with CD.

CONCLUSIONS

These statements provide guidance on how and when to intensify or de-intensify treatment for a broad spectrum of patients with CD.

Immunomodulator Withdrawal From Anti-TNF Therapy Is Not Associated With Loss of Response in Inflammatory Bowel Disease

BACKGROUND AND AIMS

The benefit of concomitant immunomodulators (thiopurines or methotrexate) in patients with inflammatory bowel disease (IBD) on anti-tumor necrosis factor α (anti-TNF) (infliximab or adalimumab) maintenance therapy is debated. We compared outcomes after immunomodulator withdrawal vs continuation of combination therapy.

METHODS

This was a retrospective cohort study in a general hospital and a tertiary referral center. We included adult IBD patients, receiving anti-TNF therapy for ≥4 months, plus an immunomodulator at baseline, between January 1, 2011, and January 1, 2019. The primary endpoints were loss of response (LOR) (ie, anti-TNF discontinuation because of disease activity) and anti-drug antibodies. Adjusted hazard ratios (aHRs) were calculated by mixed-effects Cox regression analysis.

RESULTS

We included 614 treatment episodes of combination therapy in 543 individuals, yielding 1664 patient-years of follow-up. The immunomodulator was withdrawn in 296 (48.2%) episodes after 0.9 (interquartile range, 0.6-2.1) years, which was not associated with a higher risk of LOR (aHR, 1.08; 95% confidence interval [CI], 0.72-1.61), although anti-drug antibodies were detected more frequently (aHR, 2.14; 95% CI, 1.17-3.94), compared with continuation. Clinical remission at the time of withdrawal reduced the risk of LOR (aHR, 0.48; 95% CI, 0.25-0.93), while longer duration of combination therapy before withdrawal decreased the risk of anti-drug antibodies (HR per year, 0.56; 95% CI, 0.32-0.91). Higher prewithdrawal infliximab trough levels reduced the subsequent risks of anti-drug antibodies and LOR. Infliximab trough levels were lower after immunomodulator withdrawal (P = .01).

CONCLUSIONS

Patients who withdrew the immunomodulator in this retrospective cohort were not at increased risk of LOR within the following 1-2 years, but an increase in anti-drug antibodies was observed. Our findings require prospective validation, preferably in adequately powered randomized controlled trials.

The efficacy of immunomodulators in the prevention and suppression of anti-drug antibodies to anti-tumor necrosis factor therapy in inflammatory bowel disease

The development of biological agents against tumor necrosis factor (TNF) has revolutionized the management of inflammatory bowel disease (IBD), frequently achieving induction and maintenance of remission in both ulcerative colitis and Crohn's disease. However, a loss of response due to the development of anti-drug antibodies (ADA) is seen annually in approximately 20% of IBD patients receiving anti-TNF therapy. Current evidence suggests that the use of immunomodulators (IMM), such as thiopurines (azathioprine and 6-mercaptopurine) or methotrexate, may prevent or suppress ADA formation. In this article, we present a comprehensive review of the available literature regarding the efficacy of IMM in the prevention and suppression of ADA development to anti-TNF therapy in patients with IBD.

Use of thiopurines in inflammatory bowel disease: an update

Inflammatory bowel disease (IBD), once considered a disease of the Western hemisphere, has emerged as a global disease. As the disease prevalence is on a steady rise, management of IBD has come under the spotlight. 5-Aminosalicylates, corticosteroids, immunosuppressive agents and biologics are the backbone of treatment of IBD. With the advent of biologics and small molecules, the need for surgery and hospitalization has decreased. However, economic viability and acceptability is an important determinant of local prescription patterns. Nearly one-third of the patients in West receive biologics as the first/initial therapy. The scenario is different in developing countries where biologics are used only in a small proportion of patients with IBD. Increased risk of reactivation of tuberculosis and high cost of the therapy are limitations to their use. Thiopurines hence become critical for optimal management of patients with IBD in these regions. However, approximately one-third of patients are intolerant or develop adverse effects with their use. This has led to suboptimal use of thiopurines in clinical practice. This review article discusses the clinical aspects of thiopurine use in patients with IBD with the aim of optimizing their use to full therapeutic potential.

Combination Immunotherapy Use and Withdrawal in Pediatric Inflammatory Bowel Disease-A Review of the Evidence

Evidence-based guidelines have been developed outlining the concomitant use of anti-tumor necrosis factor alpha (anti-TNF) agents and immunomodulators including azathioprine (AZA) and methotrexate (MTX) in both adult and pediatric populations. However, there exists a paucity of data guiding evidence-based strategies for their withdrawal in pediatric patients in sustained remission. This narrative review focuses on the available pediatric evidence on this question in the context of what is known from the larger body of evidence available from adult studies. The objective is to provide clarity and practical guidance around who, what, when, and how to step down pediatric patients with inflammatory bowel disease (IBD) from combination immunotherapy. Outcomes following withdrawal of either of the two most commonly used anti-TNF therapies [infliximab (IFX) or adalimumab (ADA)], or immunomodulator therapies, from a combination regimen are examined. Essentially, a judicious approach must be taken to identify a significant minority of patients who would benefit from treatment rationalization. We conclude that step-down to anti-TNF (rather than immunomodulator) monotherapy after at least 6 months of sustained clinical remission is a viable option for a select group of pediatric patients. This group includes those with good indicators of mucosal healing, low or undetectable anti-TNF trough levels, lack of predictors for severe disease, and no prior escalation of anti-TNF therapy. Transmural healing and specific human leukocyte antigen (HLA) typing are some of the emerging targets and tools that may help facilitate improved outcomes in this process. We also propose a simplified evidence-based schema that may assist in this decision-making process. Further pediatric clinical studies are required to develop the evidence base for decision-making in this area.

AGA Technical Review on the Medical Management of Moderate to Severe Luminal and Perianal Fistulizing Crohn's Disease

The incidence and prevalence of Crohn's disease (CD) is rising globally. Patients with moderate to severe CD are at high risk for needing surgery and hospitalization and for developing disease-related complications, corticosteroid dependence, and serious infections. Optimal management of outpatients with moderate to severe luminal and/or fistulizing (including perianal) CD often requires the use of immunomodulator (thiopurines, methotrexate) and/or biologic therapies, including tumor necrosis factor-α antagonists, vedolizumab, or ustekinumab, either as monotherapy or in combination (with immunomodulators) to mitigate these risks. Decisions about optimal drug therapy in moderate to severe CD are complex, with limited guidance on comparative efficacy and safety of different treatments, leading to considerable practice variability. Since the last iteration of these guidelines published in 2013, significant advances have been made in the field, including the regulatory approval of 2 new biologic agents, vedolizumab and ustekinumab. Therefore, the American Gastroenterological Association prioritized updating clinical guidelines on this topic. To inform the clinical guidelines, this technical review was completed in accordance with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework. The review addressed the following focused questions (in adult outpatients with moderate to severe luminal CD): overall and comparative efficacy of different medications for induction and maintenance of remission in patients with or without prior exposure to tumor necrosis factor-α antagonists, comparative efficacy and safety of biologic monotherapy vs combination therapy with immunomodulators, comparative efficacy of a top-down (upfront use of biologics and/or immunomodulator therapy) vs step-up treatment strategy (acceleration to biologic and/or immunomodulator therapy only after failure of mesalamine), and the role of corticosteroids and mesalamine for induction and/or maintenance of remission. Finally, in adult outpatients with moderate to severe fistulizing CD, this review addressed the efficacy of pharmacologic interventions for achieving fistula and the role of adjunctive antibiotics without clear evidence of active infection.

De-escalation of medical therapy in inflammatory bowel disease

Treatment strategies for inflammatory bowel disease (IBD) now increasingly target deep remission, yet the resultant more aggressive use of medical therapy is associated with potentially serious adverse events and significant costs. It is, therefore, of vital importance to consider when, how and in whom medical therapy may be safely de-escalated. This issue is of great potential relevance in the current SARS-Cov-2 pandemic. In this review, we first discuss the rationale for drug withdrawal in IBD, before considering the available data on withdrawal of 5-aminosalicylates (5-ASA), immunomodulators (IM) and biological therapy in both ulcerative colitis (UC) and Crohn's Disease (CD). We consider how to identify patients most appropriate for drug withdrawal and outline a potential monitoring strategy for the early detection of relapse following drug withdrawal. We conclude with important future perspectives in this challenging field, and highlight ongoing trials that are likely to shape practice in the years to come.

The shining DIAMOND for evidence-based treatment strategies for Crohn's disease

Anti-tumor necrosis factor (TNF)-α antibodies are effective therapeutic agents to treat inflammatory bowel disease (IBD). In the biologic era, the development of immunogenicity has been a critical issue for secondary loss of response. The superiority of anti-TNF therapy in combination with immunomodulators (IMs) is well-established for infliximab (IFX) but less evident for adalimumab (ADA). To clarify the contribution of thiopurines to ADA-treated patients with Crohn's disease (CD), the deep remission of immunomodulator and adalimumab combination therapy for Crohn's disease (DIAMOND) studies provided the first randomized comparison of efficacy between ADA monotherapy and ADA with thiopurine. The results of the DIAMOND and DIAMOND2 studies revealed the appropriate ADA therapeutic strategy for immunosuppressant-naïve patients with active CD based on therapeutic drug monitoring, endoscopic findings and clinical issues regarding the use of thiopurines.

Pancreatitis associated with azathioprine and 6-mercaptopurine use in Crohn's disease: a systematic review

Thiopurines are proven agents in the treatment of Crohn's disease. While pancreatitis is recognised as an adverse event associated with therapy, the effect size and morbidity of thiopurine-induced pancreatitis is not known. The aim of this systematic review and meta-analysis was to quantify the risk of pancreatitis with azathioprine and 6-mercaptopurine (6-MP) within Crohn's disease. We searched six electronic databases from inception to 29 October 2019. The primary outcomes measures were the occurrence of pancreatitis. We calculated pooled OR with corresponding 95% CIs for risk of pancreatitis. A number needed to harm analysis was performed. The search identified 4418 studies, of which 25 randomised controlled trials met the criteria for inclusion. The number of patients treated with azathioprine to cause an episode of pancreatitis was 36 (induction of remission) and 31 (maintenance of remission). The risk of pancreatitis in patients receiving azathioprine across all contexts was 3.80%, compared with a control risk of 0.2% (placebo) and 0.5% (5-aminosalicylic acid agents). There was no difference seen between 6-MP and placebo, although this was a low certainty result due to imprecision from very low event numbers and patient numbers. There is a probably increased occurrence of pancreatitis when azathioprine is used in Crohn's disease (moderate certainty), with incidence overall approximately 3.8%. Most cases are mild and resolve on cessation of therapy and no mortality was reported. There was no increased occurrence seen when using 6-MP, although this is a low certainty finding. PROSPERO prior to the study (CRD42019138065).

Relapse From Deep Remission After Therapeutic De-escalation in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

We conducted a systematic review and meta-analysis evaluating the relapse rate after therapeutic de-escalation in inflammatory bowel disease [IBD] patients who achieved deep remission [DR].

METHODS

We searched MEDLINE, EMBASE, and major gastroenterology conferences up to July 2019 for studies reporting relapse in adult patients with DR who subsequently underwent therapeutic de-escalation. Eligible studies defined DR as at least a combination of clinical remission and mucosal healing/endoscopic remission. The primary outcome was cumulative 1-year and 2-year relapse rates after therapeutic de-escalation. Secondary outcomes were relapse rates in ulcerative colitis [UC] and Crohn's disease [CD], relapse after anti-tumour necrosis factor-α [anti-TNFα] de-escalation, and the rate of disease response recapture following re-escalation.

RESULTS

Thirteen studies encompassing 837 patients were identified. The cumulative relapse rate after therapeutic de-escalation was 28.7% within 1 year [12 studies], and 38.4% within 2 years [eight studies]. Relapse rates within 1 year and 2 years were comparable between UC [five studies; 25.4% and 37.4%] and CD [seven studies; 34.1% and 39.9%]. Ten studies reported de-escalation of anti-TNFα, of which 29.8% patients relapsed within 1 year and 41.4% within 2 years. Response recapture following re-escalation [eight studies] was 75.4%.

CONCLUSIONS

Despite achieving deep remission, therapeutic de-escalation in this patient population is associated with significant relapse risk within 1 year and 2 years. This risk is more pronounced in patients requiring anti-TNFα for management, likely because of more severe disease. Similar rates of relapse were reported among UC and CD within these time periods. These findings suggest that combined clinical and endoscopic remission should not be an impetus to consider therapeutic de-escalation.

Vitamin D metabolites are lower with active Crohn's disease and spontaneously recover with development of remission

BACKGROUND

Vitamin D deficiency is associated with active Crohn's disease (CD). However, it remains unclear if lower 25-hydroxyvitamin D [25(OH)D] concentration is the cause, or consequence, of intestinal inflammation. Existing literature has focused on circulating 25(OH)D rather than the active metabolite 1,25(OH)₂D, or its breakdown product, 24,25(OH)₂D. We aimed to characterise vitamin D metabolism in a cohort of patients with active and inactive CD.

METHODS

Fifty-four patients with CD and not on corticosteroids or vitamin D supplements, were enrolled in a 6-month prospective cohort study. Sera were collected on enrolment and at 6 months and tested for 25(OH)D, 1,25(OH)₂D, 24,25(OH)₂D using liquid chromatography tandem mass spectroscopy as well as vitamin-D-binding protein.

RESULTS

There were no differences in 25(OH)D or 1,25(OH)₂D levels between participants with active versus inactive disease. Levels of 24,25(OH)₂D were significantly lower in those with active compared with inactive disease (mean 3.9 versus 6.0 µmol/l; p = 0.007) and therefore the ratio of 25(OH)D:24,25(OH)₂D was higher (mean 17.3 versus 11.1; p = 0.001). In those patients with active disease who achieved remission, there was a mean increase in 25(OH)D of 32.3 nmol/l (i.e. to a level in the sufficient range) and 24,25(OH)₂D of 2.1 µmol/l. These increases were not seen in patients with persistently active or inactive disease.

CONCLUSION

Levels of 24,25(OH)₂D, but not 25(OH)D, were lower in patients with active CD, and spontaneously increased with resolution of underlying inflammation. The utility of 24,25(OH)₂D as a biomarker of disease activity and vitamin D status in CD warrants further exploration.