Trend towards dose reduction of azathioprine as monotherapy in inflammatory bowel disease patients: what about for combination therapy?

On-demand reconstitutable hyaluronic acid-doped azathioprine microcrystals effectively ameliorate ulcerative colitis via selective accumulation in inflamed tissues

Although CD44-targeted delivery of pure drug microcrystals of azathioprine (AZA) could be a desirable approach to treat ulcerative colitis (UC), premature drug release and systemic absorption before reaching the colitis region remain a major obstacle. In this study, to overcome these limitations, we developed on-demand reconstitutable HA-doped AZA microcrystals (EFS/HA-AZAs) via incorporating hyaluronic acid (HA)-doped AZA microcrystals (HA-AZAs) into a Eudragit FS (EFS) microcomposite. Since EFS acts as a protective layer, the premature release of AZA in the simulated conditions of the stomach and small intestine was substantially reduced, while HA-AZAs were successfully reconstituted from the EFS/HA-AZAs in the colonic environment, resulting from the pH-triggered dissolution of EFS. After complete reconstitution of HA-AZAs in the colon, HA-AZAs selectively accumulated in the inflamed region via the HA-CD44 interaction. Owing to successful colitis-targeted delivery, EFS/HA-AZAs showed potent anti-inflammatory effects in a dextran sulfate sodium-induced murine colitis model within 7 days without systemic toxicity. These results suggest that EFS/HA-AZAs could be a promising drug delivery system for UC treatment.

Low dose of azathioprine is effective to induce and maintain remission in active Crohn disease: A prospective observational study

Azathioprine (AZA) 2 to 2.5 mg/kg/d is recommended for European patients with Crohn disease (CD), but several Asian studies reported that low dose of AZA was also effective to treat CD. To confirm those observations, we perform this prospective observational study to compare the efficacy and safety of low and standard doses of AZA in the treatment of active CD.This was a prospective, open-labeled observational study. Two hundred twenty-six active CD patients were divided into 2 groups and treated with AZA 1.5 or 2.0 mg/kg/d respectively, combined with steroid therapy. Patients were followed up for 96 weeks. The complete remission (CR) rate, response rate, relapse rate, and adverse effect rate were assessed at weeks 24, 48, and 96 by intention-to-treat (ITT) analysis.Azathioprine 1.5 mg/kg/d showed no significant difference compared with AZA 2 mg/kg/d in CR rate, response rate and relapse rate by ITT analysis at week 24, 48, or 96 (all P > .05). Their adverse effect rates had no significant difference either (P > .05). Up to 21.7% (49/226) of the patients reported adverse events and 69.4% (34/49) of them were myelosuppresion.Azathioprine 1.5 mg/kg/d combined with steroids is as effective as AZA 2.0 mg/kg/d to induce remission of active CD in the first 6 months, and to maintain remission of inactive CD in the first 2 years, without increasing the recurrence of active CD after clinical remission. The most common adverse effect is myelosuppression.

De-escalation of Therapy in Inflammatory Bowel Disease

PURPOSE OF REVIEW

Currently, inflammatory bowel disease treatment is based on immunomodulators (IM) and/or biologic as this strategy may prevent the development of irreversible damage. Nevertheless, long-term treatment may be associated with non-negligible side effects and with high costs, and therefore the question on whether therapy can be de-escalated is often posed in clinical practice.

RECENT FINDINGS

Recent studies have shown a predictable rate of relapse after stop biologic or IM therapy withdrawal. Overall, around 40-50% of patients will eventually relapse over the following year after drug withdrawal, and the rates will increase over time. Stratification of patients and therapeutic drug monitoring could be promising alternatives to guide therapeutic management. We reviewed the current evidence on de-escalation strategy and summarised the recent results on discontinuation and dose reduction. Nowadays, de-escalation strategy is still a case-by-case decision in highly selected patients.

A Systematic Review and Meta-Analysis of 6-Thioguanine Nucleotide Levels and Clinical Remission in Inflammatory Bowel Disease

BACKGROUND AND AIMS

Thiopurines are widely used in the management of inflammatory bowel diseases. However, their minimum effective dose and dose-response relationship remain undefined, and evidence about their use in clinical practice is mostly heterogeneous. This systematic review and meta-analysis aimed: i] to assess the clinical value of 6-thioguanine nucleotide thresholds; and ii] to compare mean 6-thioguanine nucleotide concentrations between patients in clinical remission vs. those with active disease.

METHODS

A systematic literature search was carried out using four databases. Statistical heterogeneity was assessed with the I2 statistic followed by subgroup and sensitivity analyses. Odds ratios were computed using the random-effects model.

RESULTS

A total of 1384 records were identified in the systematic search, of which 25 were retained for further analysis: 22 were used in the cut-off comparisons and 12 were used in the 6-thioguanine nucleotide mean differences analysis. The global odds ratio for remission in patients with 6-thioguanine nucleotide levels above the predefined thresholds was 3.95 (95% confidence interval [CI], 2.63-5.94; p < 0.001]. When considering the different thresholds individually, the odd ratios were significant for values above 235 pmol/8 × 108 and 250 pmol/8 × 108 red blood cells [2.25 and 4.71, respectively]. Mean 6-thioguanine nucleotide levels were higher among patients in clinical remission, with a pooled difference of 63.37 pmol/8 × 108 red blood cells [95% CI, 31.81-94.93; p < 0.001].

CONCLUSIONS

This study reinforces the link between 6-thioguanine nucleotide levels and clinical remission in inflammatory bowel diseases, also exploring the validity of specific 6-thioguanine nucleotide thresholds to predict clinical outcomes.