Impact of Chronotherapy on 6-Mercaptopurine Metabolites in Inflammatory Bowel Disease: A Pilot Crossover Trial

Abstract

Introduction: Chronotherapy is the timing of medication according to biological rhythms of the host to optimize drug efficacy and minimize toxicity. Efficacy and myelosuppression of azathioprine/6-mercaptopurine (AZA/6-MP) are correlated with the metabolite 6-thioguanine, while the metabolite 6-methylmercaptopurine correlates with hepatotoxicity.

Methods: This was a single-center, 10-week prospective crossover trial involving 26 participants with inactive inflammatory bowel disease (IBD) on a stable dose and time of AZA or 6-MP therapy. Participants were switched to the opposite delivery time (morning or evening) for 10 weeks, and metabolite measurements were at both time points.

Results: In the morning vs evening dosing, 6-thioguanine levels were 225.7 ± 155.1 vs 175.0 ± 106.9 ( P < 0.01), and 6-methylmercaptopurine levels were 825.1 ± 1,023.3 vs 2,395.3 ± 2,880.3 ( P < 0.01), with 69% (18 out of 26) of participants had better metabolite profiles in the morning. Participants with optimal dosing in the morning had an earlier chronotype by corrected midpoint of sleep.

Discussion: In the first study on a potential role of chronotherapy in IBD, we found (i) morning dosing of AZA or 6-MP resulted in more optimal metabolite profiles and (ii) host chronotype could help identify one-third of patients who would benefit from evening dosing. Circadian regulation of metabolic enzymes of AZA/6-MP activity in the liver is the likely cause of these differences. This pilot study confirms the need to incorporate chronotherapy in future multicenter clinical trials on IBD disease.

Trial registration: ClinicalTrials.gov NCT04304950 NCT0430495..

Figure 1.

Consolidated Standards of Reporting Trials. 6-MMP, 6-methylmercaptopurine; AZA/6-MP, azathioprine/6-mercaptopurine.

Figure 2.

Schematic of the experimental protocol. It was determined whether participants took their azathioprine/6-mercaptopurine (AZA/6-MP) medication consistently in either an am (06:00–12:00 hours) or pm (18:00–0:00 hours) schedule. If patients did and met the other inclusion and exclusion criteria, they were invited to participate. If agreeable, after completing baseline questionnaires and blood tests, participants change the time of their medication dosing to the alternative time of day from their baseline for 10 weeks. Blood work and clinical questionnaires were then repeated.

Figure 3.

Impact of chronotherapy on azathioprine/6-mercaptopurine (AZA/6-MP) metabolites. Metabolite levels measured at 2 different time points in each inflammatory bowel disease individual, either in the am (06:00–12:00 hours) or in the pm (18:00–0:00 hours) for at least 10 weeks ± 3 days in inactive Crohn's disease (CD) and ulcerative colitis (UC). Data are shown for (a) 6-thioguanine (T-TG) and (b) 6-methyl-mercaptopurine (6-MMP). Data were analyzed by nonparametric paired analysis (Wilcoxon signed-rank test).

Figure 4.

Corrected midpoint of sleep (McSF) by Munich Chronotype. Questionnaire compared with time of optimal thiopurine metabolite profile. McSF was calculated my Munich Chronotype Questionnaire at the initial visit. Optimal metabolite profiles were estimates as increased 6-thioguanine (T-TG) and lower 6-methyl-mercaptopurine (6-MMP). If no change in metabolite profile participants were excluded from analysis. The time of McSF between the 2 groups was compared by circular analysis (Hotelling 2-sample test). Azathioprine/6-mercaptopurine (AZA/6-MP).

Figure 5.

Circadian oscillation of metabolic enzymes. Using publicly available data from the Circadian Expression Profiles Database (http://circadb.hogeneschlab.org/), we examined whether metabolic enzymes of azathioprine/6-mercaptopurine (AZA/6-MP) were under circadian regulation. Several key enzymes in the metabolic pathway such as hypoxanthine guanine phosphoribosyl transferase (HRPT) and xanthine dehydrogenase (Xdh) had robust circadian oscillation based on time of day.