6-mercaptopurine Research Articles

Curcumin Shown Ineffective in Preventing Postsurgical Recurrent Crohn Disease

Recurrence of Crohn disease after a resection is expected. To date, the only agents shown to delay recurrence are infliximab and mercaptopurine (6MP).

PF182 CLINICOBIOLOGIC CHARACTERISTICS AND OUTCOME OF ELDERLY FRAIL PATIENTS WITH ACUTE LYMPHOBLASTIC LEUKEMIA INCLUDED IN A SPECIFIC PROTOCOL (ALL‐07FRAIL)

Background:Elderly patients with ALL are frequently excluded from clinical studies, especially if they have criteria of frailty. Treatment of these patients is considered palliative, but here are scarce studies analysing the tolerability and outcome of elderly frail patients included in specific trials.Aims:Here we present the clinicobiologic characteristics and outcome of elderly frail patients with Philadelphia chromosome‐negative (Ph‐neg) ALL included in the ALL‐07FRAIL (NCT01358201) study from the Spanish PETHEMA Group.Methods:Older (55–65 yrs.) and elderly (>65 yrs.) patients with Ph‐neg ALL with Charlson comorbidity index >3 were included in this study. Treatment schedule: pre‐phase (dexamethasone [DXM] for 1 week + triple intrathecal therapy [TIT]). Induction: vincristine (VCR) 1 mg/week x 4 wks and DXM (10 mg/m2/d x 28d) and TIT (d1 and d35). No consolidation. Maintenance: mercaptopurine (MP) (50 mg/m2/d) and methotrexate (MTX) (20 mg/m2/wk) for 2 years from CR, with monthly reinductions with VCR (1 mg), DXM (40 mg/m2, d1,2) and TIT during the 1st year.Results:From 2008 to 2018, 58 patients (pts) were included in the ALL FRAIL07 study. Mean (SD) age 73 (7) yrs., 42 pts (72%) over 70 yrs., 38 males (66%), median WBC count 8.2 x109/L (0.3–475), CNS involvement 5 pts (9%), B‐cell precursor ALL 48/56 (86%)(pro‐B [n = 12], common [n = 23], pre‐B [n = 12], non‐specified [n = 1]), T‐ALL 8/56 (14%)(pro‐T [n = 1], pre‐T [n = 4], mature T [n = 1], non‐specified [n = 2]). Results of induction treatment (n = 57, 1 on treatment): early death 9 (16%), failure 17 (30%), complete remission 31 (54%). The most frequent Grade 3–4 toxicities in induction were: neutropenia 39/51 pts (77%), thrombocytopenia 30/51 (59%), infection 11/51 (22%), neurologic 4/49 (8%) and gastrointestinal 2/49 (4%). Outcome of CR patients: treatment‐related mortality 6 (19%), withdrawn from study 2 (6%), relapse 20 (65%), persistent CR1 3 (10%). The cumulative incidence of relapse at 3‐yrs was 80% (median: 11.1 months [95%CI: 5.2–25.9]). With a median follow‐up of 23.7 months (0.1–53.7), 4 patients are alive, with a median OS of 7.7 months (95% CI, 5.6–9.9)(Figure 1).Summary/Conclusion:Older and elderly frail patients with Ph‐neg ALL can benefit from a structured study using non‐genotoxic drugs, with good tolerability and acceptable CR rate and survival. These results could serve as control for strategies including new drugs in this difficult‐to‐treat population.image

The NSD2 p.E1099K Mutation in Relapse Pediatric Acute Lymphoblastic Leukemia Is Linked to Mercaptopurine Resistance

Introduction: While the outcome for children with acute lymphoblastic leukemia (ALL) has improved dramatically, the prognosis for those who relapse remains poor. One of the most common alterations found at relapse is the p.E1099K missense change within the SET domain of NSD2, a histone methyltransferase that di-methylates histone 3 lysine 36 (H3K36). NSD2 has 3 isoforms, two of which, Type II (canonical) and REIIBP (C-terminal), contain the SET domain, and another, Type I (N-terminal), that does not. The p.E1099K mutation leads to increased enzymatic activity, but pathways leading to a clonal advantage are unknown in ALL.Methods: We used short hairpin RNAs (shRNAs) to target knockdown of two combinations of NSD2 isoforms: shI/II targets Types I and II, shII/RE targets Type II and REIIBP. Three different B-cell lines (Reh, 697, and KOPN-8) with 2 wildtype (WT) copies of NSD2 were stably transduced with shII/RE. Two B-Cell lines, RS4;11 and RCH-ACV, heterozygous for the NSD2 p.E1099K mutation, were transduced with shI/II and shII/RE. As a control, each B-cell line was stably transduced with a scrambled non-targeting (NT) shRNA. NSD2 knockdown was confirmed by Western Blots.Cell lines were treated for 5 days with chemotherapy agents commonly used in pediatric ALL treatments (mercaptopurine (MP), cytarabine, methotrexate, prednisone, and doxorubicin). Cytotoxicity was assessed by CellTiter- Glo® and significance between IC50s was determined by ANOVA and post hoc Tukey test. Cell proliferation was measured by cell counting with trypan blue. Cell cycle progression in RS4;11 lines was monitored with Edu staining and flow cytometry with and without exposure to MP.Results: Similar to previously reported results, knockdown of NSD2 in the 3 WT B-cell lines had no effect on cell proliferation. However, shI/II reduced growth by 40% in RS4;11 and 20% in RCH-ACV, while shII/RE decreased proliferation by 45% in RS4;11 and 55% in RCH-ACV when compared to their NT control. In RS4;11, both shI/II and shII/RE led to a similar 10% decrease in cells progressing through S phase compared to NT, which could be due to either a slower progression through cell cycle or less cells entering the cell cycle.Knockdown of NSD2 resulted in sensitivity to 6MP compared to NT in both RS4;11 and RCH-ACV lines. RS4;11 shII/RE had an IC50 3.2-fold more sensitive ( p<.01) and the RS4;11 shI/II IC50 was 1.25-fold more sensitive (NS) versus the NT control. Similarly, RCH-ACV shII/RE had an IC50 3.4-fold more sensitive (p<.01) and the RCH-ACV shI/II IC50 was 2.6-fold more sensitive (p<.01) compared to the NT control. No significant changes in drug sensitivity were noted for the 3 WT NSD2 knockdown B-cell lines compared to their NT controls.During a 120 hour exposure to MP, 34% more RS4;11 shII/RE cells were arrested in the G phase than NT controls, while 26% more RS4;11 shI/II cells were arrested in G phase relative to NT controls. This result indicates MP exposure leads to a reduced percentage of knockdown cells able to progress through the cell cycle. Overall, simultaneously reduced expression of Type II and REIIBP had a greater effect of on cell proliferation and MP response compared to the co-reduction of Types I and II NSD2 in the p.E1099K heterozygous cell lines.Conclusion: The p.E1099K mutation confers a growth advantage and resistance to MP, a cornerstone of ALL therapy. Concurrent reduction of Type II and REIIBP expression by shII/RE resulted in the largest impact on proliferation and MP sensitivity. Both of these isoforms include the SET domain containing the p.E1099K mutation, which indicates one or both isoforms could be responsible for changes in the chromatin state and other possible alterations that lead to a clonal advantage. Based on our findings, determining the mechanism of resistance to MP imparted by NSD2 p.E1099K is now a top priority. DisclosuresNo relevant conflicts of interest to declare.

Adsorption of mercaptopurine drug on the BN nanotube, nanosheet and nanocluster: a density functional theory study

ABSTRACTWe have investigated the interaction of mercaptopurine (MP) drug with BN nanotube, nanosheet and nanocluster using density functional theory calculations in the gas phase, and aqueous solution. We predicted that the MP drug tends to be physically adsorbed on the surface of BN nanosheet with an adsorption energy (Ead) about −3.2 kcal/mol. The electronic properties of BN nanosheet are not affected by the MP drug, and this sheet is not a sensor. But the electronic properties of BN nanotube and nanocluster are significantly sensitive to this drug in both gas phase, and aqueous solution. The BN nanocluster suffers from a long recovery time (8.8 × 108 s) because of a strong interaction (Ead = −28.6 kcal/mol), and this cluster is not a proper sensor for MP detection. But the BN nanotube benefits from a short recovery time about 49.5 s at room temperature, and may be a promising candidate for application in the MP sensors. The water solvent decreases the strength of interaction between the BN nanotube, and MP drug, but it does not affect the electronic sensitivity of the nanotube sensibly.

Biochemical efficacy of tioguanine in autoimmune hepatitis: a retrospective review of practice in the Netherlands.

SummaryBackgroundAzathioprine (AZA) and mercaptopurine (MP) are the cornerstone of steroid‐sparing strategies in autoimmune hepatitis (AIH). Up to 20% of patients do not tolerate or respond to these regimens.AimTo evaluate retrospectively the tolerability and efficacy of tioguanine (thioguanine) (TG) therapy in selected patients with AIH and AIH variant syndromes.MethodsRecords of 52 patients who received TG therapy were retrieved from nine hospitals in the Netherlands. Indications for TG treatment were intolerable side effects on AZA or MP (n = 38), insufficient response (n = 11) or first‐line treatment (n = 3). Treatment efficacy was defined as normalisation of serum aminotransferases and serum immunoglobulin G.ResultsNo serious adverse events occurred in patients treated with TG during a median follow‐up of 18 months (range 1‐194). Treatment was well tolerated in 41 patients (79%), whereas four had tolerable (8%) and seven (13%) intolerable side effects. Thirty‐eight patients were treated with TG after intolerable side effects on AZA or MP; 29 patients continued TG therapy of whom 24 (83%) achieved complete biochemical remission, four (14%) had incomplete and one (3%) had no response; nine discontinued treatment. Seven of 11 patients with insufficient response to AZA or MP were responsive to TG, three with complete and four with incomplete biochemical remission; four discontinued due to intolerance (n = 2) and non‐response (n = 2). TG was effective in all AIH patients as first‐line maintenance treatment.ConclusionIn our retrospective review of TG therapy in selected patients with AIH or AIH variants who previously failed on AZA or MP, TG appeared tolerable with biochemical efficacy.

Three Faces of Mercaptopurine Cytotoxicity In Vitro: Methylation, Nucleotide Homeostasis, and Deoxythioguanosine in DNA.

Mercaptopurine (MP) is a cytotoxic thiopurine important for the treatment of cancer and autoimmune diseases. MP and other thiopurine drugs undergo extensive intracellular metabolism, but the mechanisms of action are poorly characterized. In particular, it is unknown how different metabolites contribute to cytotoxicity and incorporation of thiopurine bases into DNA. The aim of this study was to ask whether cytotoxicity results from the incorporation of thioguanosine nucleotides into DNA, an alternative thiopurine metabolite, or a combination of factors. Therefore, we measured the cytotoxicity, metabolism, and incorporation of thioguanosine into DNA in response to MP or MP metabolites. Thiopurine metabolites varied in cytotoxicity, with methyl-thioinosine-mono-phosphate and thioguanosine-tri-phosphate the most toxic, and the methyl-thioguanosine nucleotides the least. We show, using liquid chromatography-tandem mass spectrometry, how different metabolites may perturb biochemical pathways, particularly disrupting guanosine nucleotide homeostasis, that may contribute to the mechanism of action of thiopurines. Although there was no correlation between metabolite cytotoxicity and the levels of 6-methylthioinosine-mono-phosphate or thioguanosine incorporation into DNA as individual factors, a combined analysis suggested that these factors together had a major influence on cytotoxicity. This study emphasizes the importance of enzymes of nucleotide homeostasis, methylation, and demethylation in thiopurine effects. These results will facilitate the development of dynamic biochemical models of thiopurine biochemistry that will improve our understanding of mechanisms of action in relevant target tissues.

A Computational Study on the Purinethol Drug Adsorption on the AlN Nanocone and Nanocluster

Using density functional theory calculations, the adsorption behavior and electronic sensitivity of an Al12N12 nanocluster, and an AlN nanocone were investigated toward purinethol (PE) drug. The drug tends to adsorbs on the AlN nanocluster and nanocone via its N atom with adsorption energies about − 38.2 and − 23.4 kcal/mol, respectively. The AlN nanocluster suffers from a long recovery time of about 3.1 × 1011 s at 298 K, and cannot be used as a sensor for PE drug. But the electrical conductivity of the AlN nanocone is largely increased by the PE drug adsorption which makes it sensitive to the drug. Also, AlN nanocone benefits from a short recovery time of about 20.8 s at room temperature. Thus, it was concluded that the AlN nanocone may be a promising candidate for detection of PE drug. We also show that by increasing the percentage of Hartree–Fock exchange in the functional, the adsorption energy is increased and the sensitivity is decreased.

Continuing Medical Education Questions: April 2018: ACG Clinical Guideline: Management of Crohn's Disease in Adults

LEARNING OBJECTIVES After this activity, the participant will describe clinical and diagnostic features of Crohn's disease that will help risk-stratify patients and identify optimal therapeutic interventions based on these individual patient features. QUESTIONS: 1. A 19-year-old woman presents with worsening diarrhea. She has 4-5 loose bowel movements per day and an occasional nocturnal bowel movement. She also complains of vague lower abdominal pain which may be related to meals or bowel movements. She has lost 5 lbs in the past 2 months. Examination reveals a simple perianal fistula draining a small amount of purulent material. Laboratory evaluation reveals no evidence of stool pathogens, but an elevated c-reactive protein prompts a colonoscopy, which demonstrates several ulcerations in the terminal ileum and a normal colon.You diagnose ileal Crohn's disease. What is the most appropriate initial therapy for this patient? A. Once daily mesalamine therapy B. Infliximab 5 mg/kg at 0, 2, and 6 weeks, then every 8 weeks C. Methotrexate D. Azathioprine 2.5 mg/kg daily 2. A 35-year-old man has been under your care for 10 years for a history of ileocolonic Crohn's disease. He was started on infliximab 2 years ago, and has been doing well on a maintenance dose of 5 mg/kg every 8 weeks. He now reports increasingly frequent loose bowel movements along with cramps and occasional blood, starting about 2-3 weeks prior to his infusions. On exam, there is no evidence of perianal abscess or fi stula. He reports compliance with his infliximab infusions, but has stopped taking the 6-mercapto purine over the last 6 months. A fecal calprotectin is elevated at 285 mcg/g (normal: <162 mcg/g). A colonoscopy reveals disease involving the terminal ileum and right colon. His infliximab trough serum level is 10 mcg/mL, and antibody to infliximab is undetectable. What is the most appropriate next treatment step for this patient? A. Switch to another anti-TNF agent B. Add back the 6-mercaptopurine C. Shorten the interval of infliximab to every 4 weeks D. Switch to an anti-integrin therapy 3. Adding a thiopurine to an anti-TNF regimen increases the risk of which of the following conditions? A. Osteoporosis B. Tuberculosis C. Cytomegalovirus colitis D. Lymphoma

Electron spin resonance identification of gamma irradiated 2,4′-dichlorodiphenyl dichloroethane and 6-mercaptopurine monohydrate in the solid state

The purpose of this study is to investigate the effects of ionizing radiation on two anticancer drugs, 2,4′-dichlorodiphenyl dichloroethane (DCP) and 6-mercaptopurine monohydrate (MPM), by using electron spin resonance (ESR) spectroscopy. For that purpose the intensity of ESR signals of the samples as a function of the microwave power was investigated in the range of 0.01–100 mW at room temperature. While unirradiated samples presented no ESR signal, irradiated samples exhibited significant ESR spectra. ESR measurements were performed at low and high temperatures to study the dosimetric features of free radicals induced by gamma irradiation. In order to obtain the dose-response curves, samples irradiated with gamma at 1, 5, 10, 15, 20, and 25 kGy dose values were used. Furthermore, the g values of the radicals and the hyperfine coupling constants were also determined. Additionally, the time dependency of the samples was analyzed to study the stability of the radicals.

HLA-DQA1-HLA-DRB1 polymorphism is a major predictor of azathioprine-induced pancreatitis in patients with inflammatory bowel disease.

Azathioprine (AZA)-induced pancreatitis is an unpredictable and dose-independent adverse event affecting 2%-7% of patients with inflammatory bowel disease (IBD) patients treated with AZA. There are no tools in clinical practice to identify at-risk individuals; however, a genome wide association study (GWAS) identified a strong association between the Class II HLA gene region polymorphism (rs2647087) and thiopurine-induced pancreatitis. To independently confirm the findings of the GWAS in an IBD cohort, to evaluate its utility in clinical practice and to offer a novel AZA treatment algorithm for IBD based on pharmacogenomic principles. A retrospective cohort study evaluated 373 AZA-exposed IBD patients from a tertiary care academic centre in London, Canada. Due to the limited number of patients taking mercaptopurine (MP), such patients were not included this cohort. All subjects underwent screening for the single nucleotide polymorphism (SNP) rs2647087 mapped to the HLA-DQA1*02:01-HLA-DRB1*07:01 haplotype and were sub-divided based on the presence (n=13) or absence (n=360) of an AZA-induced pancreatitis diagnosis. The risk of AZA-induced pancreatitis was assessed based on rs2647087 genotype. The risk of pancreatitis during AZA-therapy was highly predictable and genotype dependent: 0.53% for wild type (A/A), 4.25% (OR=4.19, 95% CI 1.02-36.45, P=0.044) for heterozygous (A/C), and 14.63% (OR=15.83, 95% CI 3.80-145.26, P=0.0001) for homozygous variant (C/C) patients. The class II HLA region (at rs2647087) is an important marker of AZA-induced pancreatitis risk. We propose a simple and clinically implementable algorithm based on rs2647087 and TPMT genotypes for AZA selection and dosing for patients with IBD.

APEX1 Polymorphism and Mercaptopurine-Related Early Onset Neutropenia in Pediatric Acute Lymphoblastic Leukemia.

PurposeMercaptopurine (MP) is one of the main chemotherapeutics for acute lymphoblastic leukemia (ALL). To improve treatment outcomes, constant MP dose titration is essential to maintain steady drug exposure, while minimizing myelosuppression. We performed two-stage analyses to identify genetic determinants of MP-related neutropenia in Korean pediatric ALL patients.Materials and MethodsTargeted sequencing of 40 patients who exhibited definite MP intolerance was conducted using a novel panel of 211 pharmacogenetic-related genes, and subsequent analysis was performed with 185 patients.ResultsUsing bioinformatics tools and genetic data, four functionally interesting variants were selected (ABCC4, APEX1, CYP1A1, and CYP4F2). Including four variants, 23 variants in 12 genes potentially linked to MP adverse reactions were selected as final candidates for subsequent analysis in 185 patients. Ultimately, a variant allele in APEX1 rs2307486was found to be strongly associated with MP-induced neutropenia that occurred within 28 days of initiating MP (odds ratio, 3.44; p=0.02). Moreover, the cumulative incidence of MP-related neutropenia was significantly higher in patients with APEX1 rs2307486 variants, as GG genotypes were associated with the highest cumulative incidence (p < 0.01). NUDT15 rs116855232 variants were strongly associated with a higher cumulative incidence of neutropenia (p < 0.01), and a lower median dose of tolerated MP throughout maintenance treatment (p < 0.01).ConclusionWe have identified that APEX1 rs2307486 variants conferred an increased risk of MP-related early onset neutropenia. APEX1 and NUDT15 both contribute to cell protection from DNA damage or misincorporation, so alleles that impair the function of either gene may affect MP sensitivities, thereby inducing MP-related neutropenia.

A randomised, double-blind, parallel-group trial to assess mercaptopurine versus placebo to prevent or delay recurrence of Crohn’s disease following surgical resection (TOPPIC)

BackgroundCrohn’s disease (CD) is a chronic, relapsing, inflammatory bowel disease. Up to 65% of patients with CD require an operation to control the disease within 10 years. Both endoscopic and clinical recurrence is common within 2 years of operation, with re-operation rates cumulating at 5% of patients per year.ObjectivesThis study assessed if the use of mercaptopurine (MP) can prevent or delay postoperative recurrence in CD.DesignAn individually randomised, multicentre, double-blind, placebo-controlled trial with follow-up at 6, 13, 31, 49, 67, 85, 103, 121, 139 and 157 weeks.SettingTwenty-nine tertiary referral hospitals in the UK.ParticipantsThose aged ≥ 16 years in Scotland (or aged ≥ 18 years in England and Wales) with a histologically confirmed diagnosis of CD (according to the Lennard-Jones criteria) and surgical intervention ≤ 3 months prior to randomisation to remove all observable disease at ileocolonic or small bowel resections. Patients were excluded if they had a known intolerance of or hypersensitivity to thiopurines; were known to require further surgery; underwent strictureplasty alone; had a stoma; or had an active or untreated malignancy or absent thiopurineS-methyltransferase (TPMT) activity. Prior to randomisation any postoperative infections were fully treated and existing treatments for CD were stopped.InterventionDaily oral dose of MP or placebo, with dose adjusted according to body weight (kg) and TPMT status. Blood samples for genetic and serological analysis were taken at randomisation with additional blood and stool samples collected at weeks 0, 13, 49, 103 and 157 for central analysis of drug metabolite and faecal calprotectin levels, with endoscopic assessment at weeks 49 and 157.Main outcome measuresThe primary end point was clinical recurrence of CD (Crohn’s Disease Activity Index score of &gt; 150 points plus 100-point rise) and the need for anti-inflammatory rescue therapy or primary surgical intervention. Secondary end points included faecal calprotectin and thioguanine levels, and assessment of endoscopic recurrence. The primary analysis was adjusted for baseline values of previous treatment with MP and azathioprine, with the adjusted analysis considered to be the primary analysis.ResultsBetween June 2008 and April 2012, 240 patients were enrolled and received at least one dose of the study drug. A total of 128 (53%) participants were randomised to receive MP and 112 (47%) to receive placebo. No randomised patients were excluded from the analysis. More patients achieved the primary end point in the placebo group (n = 26, 23.2%) than in the MP group (n = 16, 12.5%), with an adjustedp-value of 0.073 [hazard ratio (HR) 0.535, 95% confidence interval (CI) 0.27 to 1.06]. Of the smokers on MP, 3 out of 29 (10.3%) had clinical recurrence versus 12 out of 26 (46.2%) on placebo, demonstrating that MP was effective at preventing postoperative recurrence in smokers (HR 0.127, 95% CI 0.04 to 0.46) but not in non-smokers (HR 0.898, 95% CI 0.42 to 1.94). The proportion of patients experiencing adverse events was similar in the treatment and placebo groups.LimitationsThere was a lower than anticipated primary event rate (12.5% in the treatment group vs. 23.2% in the placebo group, as opposed to expected rates of 30% vs. 50%).ConclusionsThe Trial Of Prevention of Post operative Crohn’s disease (TOPPIC) is the largest single, double-blind trial assessing the use of thiopurines to prevent postoperative recurrence in CD. From the trial itself, MP was not effective in reducing the frequency of clinical postoperative recurrence of CD overall, but the data suggest that it has clinically meaningful effect among the subgroup of patients who continue to smoke after surgery.Future workExploratory analyses of possible predictors of disease recurrence using collected data and samples.Trial registrationCurrent Controlled Trials ISRCTN89489788 and EudraCT 2006-005800-15.FundingThis project was funded by the Efficacy and Mechanism Evaluation programme, a Medical Research Council and National Institute for Health Research (NIHR) partnership, and will be published in full inEfficacy and Mechanism Evaluation; Vol. 4, No. 4. See the NIHR Journals Library website for further project information.

Clinical analysis of 45 children with Langerhans cell histiocytosis

Objective To analyze the clinical data of children with Langerhans cell histiocytosis(LCH), to discuss the therapeutic effect, and to analyze the factors related to prognosis. Methods A total of 45 children diagnosed as LCH were divided into group A (18 cases with bone lesion only), group B(6 cases with soft tissue lesion), and group C(21 cases with viscera lesion) according to Shanghai Children′s Hospital-LCH-2007 scheme[SCH-LCH-2007(modified DAL-HX83/90)scheme]. (1)Initial treatment: group A was treated with Prednisone (Pred)+ Vincristine (VCR) for 28 weeks, and group B was treated with Pred+ VCR+ Etoposide (VP16)+ Mercaptopurine (6MP) for 43 weeks, and group C was treated with Pred+ VCR+ VP16+ Methotrexate (MTX)+ 6MP for 52 weeks.(2) Re-treatment scheme after relapse included: ①upgrading treatment, group A to group B, group B to group C. ②Individual treatment for group C included VP16 modification, and maintained Thymosin and/or Ciclosporin etc. Results The total survival rate was 93.3%(42/45 cases) and recurrence rate was 26.7%(12/45 cases). Children in group A and B were all effective, while 2 patients in group C died, and 1 case missed follow-up. Multi-factor analysis showed that the factors like age, sex, group, skeleton, soft tissue, erythra, lymph gland, lung, mouth, ears, hypophysis pituitary had no statistical significance, but liver, spleen and blood involvement had statistical significance in disease relapse: liver (P=0.007 1), spleen (P=0.016 9), and blood (P=0.011 1). Conclusion LCH can affect several organs of children and relapse, and modified DAL-HX83/90 scheme is very effective. The liver, spleen and hematopoiesis system involvement is correlates with the relapse. Key words: Langerhans cell histiocytosis; Chemotherapy; Child

More Dose-dependent Side Effects with Mercaptopurine over Azathioprine in IBD Treatment Due to Relatively Higher Dosing.

There are substantial global differences in the preference for mercaptopurine (MP) or its prodrug azathioprine (AZA) as first-choice thiopurine to treat inflammatory bowel diseases. Studies comparing both agents are scarce. Our aim was to compare AZA and MP in thiopurine-naive patients with inflammatory bowel disease for the frequency of side effects and efficacy. Post hoc analysis of the "Thiopurine response Optimization by Pharmacogenetic testing in Inflammatory bowel disease Clinics" (TOPIC) trial, in which thiopurine-naive patients with inflammatory bowel disease with an indication for a thiopurine were randomized for a genotype-based dose versus standard of care. For this study, Cox proportional hazard ratios (HRs) were calculated to compare AZA and MP for discontinuation rates within 5 months, incidence of hepatotoxicity, leukopenia, and gastrointestinal side effects. Treatment efficacy was compared by logistic regression. Patient characteristics were similar for patients treated with AZA (n = 494, 64.4%) and MP (n = 273, 35.6%), yet patients with MP were relatively higher dosed compared with those on AZA. Discontinuation rates within 5 months were not different, 39.3% (AZA) and 38.1% (MP), HR 0.92 (95% confidence interval, 0.72-1.17; P = 0.50); however, patients on MP were more often subjected to dose reductions (30% versus 14%, P < 0.01). Higher rates of hepatotoxicity, HR 1.93 (95% confidence interval, 1.35-2.76; P < 0.01) and leukopenia, HR 2.55 (95% confidence interval, 1.51-4.30; P < 0.01) were observed with MP, which annulled in a secondary analysis with adjustment for the higher dose and metabolite levels. Patients treated with MP were relatively higher dosed, which resulted in more dose-dependent side effects and a higher rate of dose reductions.

The effects of inherited NUDT15 polymorphisms on thiopurine active metabolites in Japanese children with acute lymphoblastic leukemia.

Thiopurines [e.g. mercaptopurine (MP)] are widely used as chemotherapeutic agents in the treatment of pediatric acute lymphoblastic leukemia with dose-limiting hematopoietic toxicity. Recently, germline variants in NUDT15 have been identified as a major genetic cause for MP-related bone marrow suppression, and there is increasing interest in the clinical implementation of NUDT15 genotype-guided MP dose individualization. Therefore, we sought to evaluate the effects of NUDT15 on thiopurine metabolism and identify pharmacologic markers to inform NUDT15 genotype-guided MP dosing. In 55 Japanese children with acute lymphoblastic leukemia, we simultaneously measured both thioguanine nucleotides (TGN) in red blood cells and DNA-incorporated thioguanine (DNA-TG) in white blood cells. TGN levels were significantly lower in patients with NUDT15 deficiency, likely because of toxicity-related MP dose reduction. In contrast, when exposed to the same dose of MP, DNA-TG accumulated more efficiently in vivo with increasing number of risk alleles in NUDT15 (P=4.0×10). Cytosolic TGN and nuclear DNA-TG were correlated positively with each other across genotype groups (P=6.5×10), but the ratio of DNA-TG to TGN was significantly higher in NUDT15-deficient patients (P=3.6×10), consistent with excessive MP activation. In conclusion, our results suggest that DNA-TG is a more relevant MP metabolite than TGN to inform NUDT15 genotype-guided dose adjustments.

Azathioprine, Mercaptopurine, and 5-Aminosalicylic Acid Affect the Growth of IBD-Associated Campylobacter Species and Other Enteric Microbes.

Campylobacter concisus is a bacterium that is associated with inflammatory bowel disease (IBD). Immunosuppressive drugs including azathioprine (AZA) and mercaptopurine (MP), and anti-inflammatory drug such as 5-aminosalicylic acid (5-ASA) are commonly used to treat patients with IBD. This study aimed to examine the effects of AZA, MP, and 5-ASA on the growth of IBD-associated bacterial species and to identify bacterial enzymes involved in immunosuppressive drug metabolism. A total of 15 bacterial strains of five species including 11 C. concisus strains, Bacteroides fragilis, Bacteroides vulgatus, Enterococcus faecalis, and Escherichia coli were examined. The impact of AZA, MP, and 5-ASA on the growth of these bacterial species was examined quantitatively using a plate counting method. The presence of enzymes involved in AZA and MP metabolism in these bacterial species was identified using bioinformatics tools. AZA and MP significantly inhibited the growth of all 11 C. concisus strains. C. concisus strains were more sensitive to AZA than MP. 5-ASA showed inhibitory effects to some C. concisus strains, while it promoted the growth of other C. concisus strains. AZA and MP also significantly inhibited the growth of B. fragilis and B. vulgatus. The growth of E. coli was significantly inhibited by 200 μg/ml of AZA as well as 100 and 200 μg/ml of 5-ASA. Bacterial enzymes related to AZA and MP metabolism were found, which varied in different bacterial species. In conclusion, AZA and MP have inhibitory effects to IBD-associated C. concisus and other enteric microbes, suggesting an additional therapeutic mechanism of these drugs in the treatment of IBD. The strain dependent differential impact of 5-ASA on the growth of C. concisus may also have clinical implication given that in some cases 5-ASA medications were found to cause exacerbations of colitis.

P-035 Efficacy of Vedolizumab Used in Combination with Mercaptopurine as a Therapy for Crohn's Disease: A Four Patient Case Study

P-035 Efficacy of Vedolizumab Used in Combination with Mercaptopurine as a Therapy for Crohn's Disease: A Four Patient Case Study

P125 Rapid increase in pan-treatment refractory Crohn's disease after transition to adult services: a regional cohort study

Background: Inflammatory bowel disease (IBD) presents in childhood in up to 15% of cases. Paediatric onset IBD (PIBD) has a more extensive and dynamically changing phenotype and a faster rising incidence than adult-onset IBD. We aimed to evaluate rates of treatment refractory disease at and then following transition to adult services. Methods: A prospective PIBD database identified a cohort of all patients discharged from our regional service since 01/01/07. A retrospective study of patients graduating from paediatric to adult IBD services through a transition process, transition event (single joint clinic) or transfer until 31/12/13 was conducted with post transfer follow-up (FU) data at a minimum of 1 year to last adult FU (LAFU). Pan-treatment exposure (PTE) was defined as exposure to all of azathioprine (AZA) or mercaptopurine (MP), methotrexate (MTX), infliximab (IFX) and adalimumab (ADA). Pan-treatment refractory (PTR) disease as those refractory (primary non-response [PNR], loss of response [LOR] or intolerance) to all of these therapies. We used the Montreal classification to describe disease location (L) and behaviour (B) phenotypes. Psychological co-morbidity was defined as a formal psychiatric diagnosis, regular psychiatry/psychology input (or intention for this if repeated family refusal), documented anxiety or depression and deliberate self-harm. Results: 138 patients graduated to adult services, 69% (95/138) had Crohn's disease (CD); 59% (56/95) male, 76% (72/95) with extensive disease (L3 or L3+L4) and 22% (21/95) B2 or B3 disease at time of transfer. Median (IQR) age at transfer 17.8 years (17.3, 18.4) and median (IQR) disease duration at transfer 5.4 years (4.6, 7.6). Median (IQR) length of FU post-transfer was 3.3 years (2.1, 5.1). 12% (11/95) had PTE with 4% (4/95) having PTR disease by time of transfer. PTE rates increased significantly to 26% (21/82) p=0.009 at LAFU and PTR disease to 18% (15/82) p=0.003; 13 patients lost to follow-up. 90% (19/21) of those with PTE had extensive disease and 48% (10/21) had B2 or B3 disease by LAFU. 80% (12/15) patients with PTR disease required bowel resection or a defunctioning stoma by LAFU, compared with 37% (30/82) of the whole CD cohort p=0.002. 24% (5/21) of those with PTE had significant psychological co-morbidity by LAFU. Conclusions: Our novel data show that pan-treatment exposure in paediatric-onset CD is already significant by time of transfer to adult services and continues to increase to affect 26% of this regional cohort within a relatively short period of adult follow-up. 18% of paediatric-onset CD patients have failed all medical treatments by LAFU and 71% with PTE require resectional or defunctioning surgery to manage disease.

The glutathione transferase Mu null genotype leads to lower 6-MMPR levels in patients treated with azathioprine but not with mercaptopurine

The conversion of azathioprine (AZA) to mercaptopurine (MP) is mediated by glutathione transferase Mu1 (GSTM1), alpha1 (GSTA1) and alpha2 (GSTA2). We designed a case-control study with data from the TOPIC trial to explore the effects of genetic variation on steady state 6-methylmercaptopurine ribonucleotide (6-MMPR) and 6-thioguanine nucleotide (6-TGN) metabolite levels. We included 199 patients with inflammatory bowel disease (126 on AZA and 73 on MP). GSTM1-null genotype carriers on AZA had two-fold lower 6-MMPR levels than AZA users carrying one or two copies of GSTM1 (2239 (1006-4587) versus 4371 (1897-7369) pmol/8 × 108 RBCs; P<0.01). In patients on MP (control group) 6-MMPR levels were comparable (6195 (1551-10712) versus 6544 (1717-11600) pmol/8 × 108 RBCs; P=0.84). The 6-TGN levels were not affected by the GSTM1 genotype. The presence of genetic variants in GSTA1 and GSTA2 was not related to the 6-MMPR and 6-TGN levels.

Susceptibility to 6-mercaptopurine toxicity related with NUDT15 and ABCC4 variants in Japanese childhood acute lymphoblastic leukemia.

6-Mercaptopurine (6-MP) is one of the main components for the treatment of childhood acute lymphoblastic leukemia (ALL). However, many patients require a dose reduction of 6-MP due to its severe toxicities. NUDT15 variants are one of the factors that cause 6-MP intolerability in Asians. In each patient with heterozygous variants of NUDT15, 6-MP intolerability differs. Therefore, we hypothesized that the combination of NUDT15 genotype with ABCC4 genotype, which is associated with 6-MP efflux, might enable to accurately predict 6-MP intolerability. We analyzed the association between 6-MP-related events and the genotypes of NUDT15 and ABCC4. All patients with both NUDT15 rs116855232 heterozygous variants and ABCC4 rs3765534 variants suffered from severe leukopenia and required 6-MP dose reduction to less than 35 mg/m2/day. In conclusion, genotyping NUDT15 and ABCC4 facilitates the prediction of 6-MP intolerability. The results of this study will improve personalized medicines in Japanese patients with childhood ALL.