Letter: Thioguanine, an under-utilised option in inflammatory bowel disease? Authors' reply

This article is linked to Vasudevan et al papers. To view these articles, visit https://doi.org/10.1111/apt.17831 and https://doi.org/10.1111/apt.17920

Letter: Thioguanine, an underutilised option in inflammatory bowel disease?

This article is linked to Vasudevan et al papers. To view these articles, visit https://doi.org/10.1111/apt.17831 and https://doi.org/10.1111/apt.17957

Key factors associated with 6-thioguanine and 6-methylmercaptopurine nucleotide concentrations in children treated by thiopurine for acute leukaemia and inflammatory bowel disease

AIMS

Azathioprine (AZA) and 6-mercaptopurine are prescribed in acute lymphoblastic leukaemia (ALL) and inflammatory bowel diseases (IBD). Metabolism to active 6-thioguanine (6TGN) and 6-methylmercaptopurine nucleotides (6MMPN) is variable but therapeutic drug monitoring (TDM) remains debatable. This study reports on factors impacting on red blood cell (RBC) metabolites concentrations in children to facilitate TDM interpretation.

METHODS

The first paediatric TDM samples received during year 2021 were analysed, whatever indication and thiopurine drug. Target concentration ranges were 200-500, <6000 pmol/8 × 108 RBC for 6TGN and 6MMPN.

RESULTS

Children (n = 492) had IBD (64.8%), ALL (22.6%) or another autoimmune disease (12.6%): mean ages at TDM were 7.5 in ALL and 13.7 years in IBD (P < .0001). ALL received 6-mercaptopurine (mean dose 1.7 mg/kg/d with methotrexate), IBD received AZA (1.9 mg/kg/d with anti-inflammatory drugs and/or monoclonal antibodies). Median 6TGN and 6MMPN concentrations were 213.7 [interquartile range: 142.5; 309.6] and 1144.6 [419.4; 3574.3] pmol/8 × 108 RBC, 38.8% of patients were in the recommended therapeutic range for both compounds. Aminotransferases and blood tests were abnormal in 57/260 patients: 8.1% patients had high alanine aminotransaminase, 3.4% of patients had abnormal blood count. Factors associated with increased 6TGN were age at TDM and thiopurine methyltransferase genotype in ALL and AZA dose in IBD. The impact of associated treatment in IBD patients was also significant.

CONCLUSION

TDM allowed identification of children who do not reach target levels or remain over treated. Including TDM in follow-up may help physicians to adjust dosage with the aim of reducing adverse effects and improve treatment outcome.

Drug rediscovery in gastroenterology: from off-label to on-label use of thioguanine in inflammatory bowel disease

Drug rediscovery refers to the principle of using 'old' drugs outside the indications mentioned in the summary of product characteristics. In the past decades, several drugs were rediscovered in a wide variety of medical fields. One of the most recent examples is the unconditional registration of thioguanine (TG), a thiopurine derivative, in patients with inflammatory bowel disease in the Netherlands. In this paper, we aim to visualise potential hurdles that hamper drug rediscovery in general, emphasise the global need for optimal use and development of potentially useful drugs, and provide an overview of the registration process for TG in the Netherlands. With this summary, we aim to guide drug rediscovery trajectories in the near future.

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

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.

Low NUDT15 expression levels due to biallelic NUDT15 variants and 6-mercaptopurine intolerance

6-Mercaptopurine (6-MP) is widely used for the treatment of paediatric leukaemia and lymphoma. Recently, germline variants in the NUDT15 gene have been identified as one of the major genetic causes for 6-MP-associated adverse effects such as myelosuppression. Patients with hypomorphic NUDT15 variants accumulate excessive levels of DNA-incorporated thioguanine in white blood cells, resulting in severe myelosuppression. Although preclinical studies suggest that these variants may influence the protein stability of NUDT15, this has not been directly characterised in patients. In this study, we report the development of a series of novel monoclonal antibodies against NUDT15, using which we quantitatively assessed NUDT15 protein levels in 37 patients with acute lymphoblastic leukaemia treated with 6-MP, using sandwich enzyme-linked immunosorbent assay (ELISA). The NUDT15 genotype was highly correlated with its protein levels (p < 0.0001), with homozygous and compound heterozygous patients showing exceedingly low NUDT15 expression. There was a positive correlation between NUDT15 protein level and 6-MP tolerance (r = 0.631, p < 0.0001). In conclusion, our results point to low NUDT15 protein abundance as the biochemical basis for NUDT15-mediated 6-MP intolerance, thus providing a phenotypic readout of inherited NUDT15 deficiency.

Clinical efficacy and safety of 6-thioguanine in the treatment of childhood acute lymphoblastic leukemia: A protocol for systematic review and meta-analysis

BACKGROUND

To systematic review the efficacy and safety of 6-thioguanine (6-TG) in the substitute of 6-mercaptopurine (6-MP) in the treatment for patients with childhood acute lymphoblastic leukemia (ALL) in the maintenance phase, and to explore its clinical application value. It provides theoretical guidance for the maintenance treatment of ALL in children from the perspective of evidence-based medicine.

METHODS

By means of computer retrieval, Chinese databases were searched: Chinese Biomedical Database (CBM), China national knowledge internet (CNKI), Chongqing Weipu Database (VIP), and Wanfang Database; Foreign databases: PubMed, The Cochrane Library, Embase, and Web of Science were applied to find out randomized controlled trial (RCT) for 6-TG in childhood acute lymphoblastic leukemia. By manual retrieval, documents without electronic edition and related conference papers were retrieved. The retrieval time ranges from the beginning of the establishment of the databases to September 1st, 2019. According to the inclusion, and exclusion criteria by 3 researchers, the literature screening, data extraction, and research methodological quality evaluation were completed. RevMan 5.3 software was applied to evaluate the quality of the included literature, and Stata 12.0 software was used to conduct meta-analysis of the outcome indicators of the included literature.

RESULTS

This study systematically evaluated the efficacy and safety of 6-TG in the substitute of 6-MP as a maintenance drug for childhood acute lymphoblastic leukemia. Through the key outcome indicators, this study is expected to draw a scientific, practical conclusion for 6-TG in the treatment of childhood acute lymphoblastic leukemia. This conclusion will provide evidence-based medical direction for clinical treatment.

CONCLUSION

The efficacy and safety of 6-TG in the substitute of 6-MP in the maintenance treatment of childhood acute lymphoblastic leukemia will be confirmed through this study. The conclusions will be published in relevant academic journals.

REGISTRATION

PROSPERO (registration number is CRD42020150466).

Primary lymphoma of the tibia in children: Two case reports

RATIONALE

Primary lymphoma of the bones (PLB) is a rare extranodal non-Hodgkin lymphoma (NHL) that is particularly rare in children. The clinical presentation and radiological features of PLB are often nonspecific, making clinical diagnosis challenging and misdiagnosis frequent. Here, we report 2 children with PLB focusing on clinical presentation, differential diagnosis, and treatment outcomes.

PATIENTS CONCERNS

A 9-year-old boy presented with left knee swelling and pain for 4 months after a fall. He was previously misdiagnosed with traumatic soft tissue injury. The second patient was an 11-year-old boy with a 6-month history of intermittent left knee pain. He was previously misdiagnosed with bone tuberculosis and chronic osteomyelitis.

DIAGNOSES

A 9-year-old boy showed an abnormal signal of the left tibia metaphysis, diaphysis, and epiphysis, and tibia with periosteal reactions and surrounding soft tissue swelling. Tumor biopsy and immunohistochemistry confirmed a diagnosis of B-cell lymphoblastic lymphoma.An 11-year-old boy showed a permeative lesion in the metaphysis and diaphysis of the left proximal tibia. Tumor biopsy and immunohistochemistry confirmed the diagnosis of diffuse large B-cell lymphoma.

INTERVENTIONS

Both patients were treated with 6 courses of NHL-Berlin-Frankfurt-Münster-95.

OUTCOMES

Both patients are in complete clinical remission with a follow-up of 27 and 18months after treatment, respectively.

LESSONS

PLB is a rare malignancy that is difficult to diagnose, particularly in children. Clinicians should increase the awareness of the disease and consider a differential diagnosis of bone lesions. Chemotherapy combined with radiotherapy is a favorable treatment for children with PLB. Early diagnosis and active treatment can improve patient prognosis.

Hepatotoxicity during 6-thioguanine treatment in inflammatory bowel disease and childhood acute lymphoblastic leukaemia: A systematic review

Background

The recently established association between higher levels of DNA-incorporated thioguanine nucleotides and lower relapse risk in childhood acute lymphoblastic leukaemia (ALL) calls for reassessment of prolonged 6-thioguanine (6TG) treatment, while avoiding the risk of hepatotoxicity.

Objectives

To assess the incidence of hepatotoxicity in patients treated with 6TG, and to explore if a safe dose of continuous 6TG can be established.

Data sources

Databases, conference proceedings, and reference lists of included studies were systematically searched for 6TG and synonyms from 1998–2018.

Methods

We included studies of patients with ALL or inflammatory bowel disorder (IBD) treated with 6TG, excluding studies with 6TG as part of an intensive chemotherapy regimen. We uploaded a protocol to PROSPERO (registration number CRD42018089424). Database and manual searches yielded 1823 unique records. Of these, 395 full-texts were screened for eligibility. Finally, 134 reports representing 42 studies were included.

Results and conclusions

We included data from 42 studies of ALL and IBD patients; four randomised controlled trials (RCTs) including 3,993 patients, 20 observational studies including 796 patients, and 18 case reports including 60 patients. Hepatotoxicity in the form of sinusoidal obstruction syndrome (SOS) occurred in 9–25% of the ALL patients in two of the four included RCTs using 6TG doses of 40–60 mg/m²/day, and long-term hepatotoxicity in the form of nodular regenerative hyperplasia (NRH) was reported in 2.5%. In IBD patients treated with 6TG doses of approximately 23 mg/m²/day, NRH occurred in 14% of patients. At a 6TG dose of approximately 12 mg/m²/day, NRH was reported in 6% of IBD patients, which is similar to the background incidence. According to this review, doses at or below 12 mg/m²/day are rarely associated with notable hepatotoxicity and can probably be considered safe.

A Short-Term Chemosensitivity Test with Different Labeled Precursors of DNA or Protein Synthesis: Correlation with Clinical Response

Blood or bone marrow samples from 15 patients with newly diagnosed acute myeloblastic leukemia undergoing remission induction treatment with daunorubicin, cytosine-arabinoside and 6-thioguanine were tested in vitro. Leukemic cells were incubated for 24 h at 37 °C with or without the drugs alone or in combination. A 3-h pulse with labelled precursors of DNA synthesis (3H-thymidine) or protein synthesis (3H-leucine) was then given separately. In vitro growth, expressed as the percentage ratio between labeled precursor uptake in treated cells and in control cells, was compared with the clinical results obtained. Three patients were not considered evaluable (death occurred too early), 8 had a complete response (CR), and 4 were disease resistant to chemotherapy. Leukemic cells of resistant-disease patients showed a significantly lower growth inhibition than cells taken from CR patients, with each drug alone or in combination, when measured with thymidine. Inhibition of leucine uptake was not related to the clinical outcome.

[Continued development of drugs: the path of thioguanine]

Continued development of existing drugs ('drug rediscovery') may offer new therapeutic options and be cost-effective. Rediscovered drugs are commonly prescribed off-label, although licensing can be important to allow safe and controlled prescription of the drugs to patients. Licensing of a new indication for a generic drug, however, is a complicated process since there is no blueprint for this and there is little interest from the pharmaceutical industry due to an unattractive cost-recovery model. In this article, we illustrate the successful license-extension for thioguanine - initially developed in 1950 for leukaemia - as a new treatment for patients with inflammatory bowel disease.

Epidemiologic and therapeutic aspects of refractory coeliac disease - a systematic review

INTRODUCTION

Refractory coeliac disease (RCD) is a rare and severe malabsorptive disease. The condition has two subtypes: RCDI and RCDII. Different treatments have been tested: and because RCD has a poor prognosis due to progress to enteropathy-associated T-cell lymphoma, the aim was to review the epidemiologic aspects and the therapeutic options for RCD.

METHODS

A systematic literature search was performed in 18 databases, and 122 records were identified. Incidence, prevalence, treatment methods and their efficacy were evaluated.

RESULTS

Among coeliac disease patients, the cumulative incidence of RCD is 1-4% per ten-year period and the prevalence is 0.31-0.38%. In the general population, the prevalence of RCD is 0.002%. Treatment of RCDI is azathioprine (effect 100%), mesalamine (effect 60%) or tioguanine (effect 83%). Treatment for RCDII is the antimetabolite cladribine (effect 81%) and autologous haematopoetic stem cell transplantation (effect 85%).

CONCLUSION

RCD is a very rare disease. The current evidence for RCDI treatment includes prednisolone in combination with the immunosuppressants azathioprine, mesalamine or tioguanine. The current evidence for RCDII treatment documents use of the antimetabolite cladribine, and if there is no effect, autologous haematopoetic stem cell transplantation may be attempted. In the future, there is a need for more effective treatments which will also prevent further progression to enteropathy-associated T-cell lymphoma.

Efficacy of thioguanine treatment in inflammatory bowel disease: A systematic review

AIM

To critically assess the available literature regarding the efficacy of thioguanine treatment in inflammatory bowel disease (IBD) patients, irrespective of the (hepato-) toxicity profile.

METHODS

A systematic literature search of the MEDLINE database using PubMed was performed using the keywords “thioguanine”, “6-TG”, “thioguanine”, “inflammatory bowel disease”, “IBD”, “Crohn’s disease”, “Ulcerative colitis” and “effectiveness” in order to identify relevant articles published in English starting from 2000. Reference lists of the included articles were cross-checked for missing articles. Reviewed manuscripts concerning the effectiveness of thioguanine treatment in IBD were reviewed by the authors and the data were extracted. Data were subsequently analyzed with descriptive statistics. Due to the lack of standardized outcomes, a formal meta-analysis was not performed.

RESULTS

A total of 11 applicable studies were found that involved the effectiveness of thioguanine therapy in IBD. Eight studies were conducted in a prospective manner, in the remaining three studies, data was collected retrospectively. In total, 353 IBD-patients (225 patients with Crohn’s disease, 119 with ulcerative colitis and nine with unclassified IBD) with prior azathioprine/mercaptopurine resistance and/or intolerance (n = 321) or de novo thioguanine administration (n = 32) were included for analysis, of which 228 (65%) had clinical improvement on thioguanine therapy, based on standard IBD questionnaires, biochemical parameters or global physician assessments. Short-term results were based on 268 treatment years (median follow-up 9 mo, range 3-22 mo) with a median daily dose of 20 mg (range 10-80 mg). Discontinuation, mostly due to adverse events, was reported in 72 patients (20%).

CONCLUSION

The efficacy of thioguanine therapy in IBD patients intolerant to conventional thiopurine therapy is observed in 65%, with short term adverse events in 20% of patients.

Thiopurine Resistance in Childhood ALL Is Mediated by PRPS1 Mutations

Mutations in the de novo purine biosynthesis enzyme PRPS1 drive thiopurine resistance in relapsed ALL.

The NPM1 mutation type has no impact on survival in cytogenetically normal AML

NPM1 mutations represent frequent genetic alterations in patients with acute myeloid leukemia (AML) associated with a favorable prognosis. Different types of NPM1 mutations have been described. The purpose of our study was to evaluate the relevance of different NPM1 mutation types with regard to clinical outcome. Our analyses were based on 349 NPM1-mutated AML patients treated in the AMLCG99 trial. Complete remission rates, overall survival and relapse-free survival were not significantly different between patients with NPM1 type A or rare type mutations. The NPM1 mutation type does not seem to play a role in risk stratification of cytogenetically normal AML.

6-thioguanine: a drug with unrealized potential for cancer therapy

Sixty years ago, 6-thioguanine (6-TG) was introduced into the clinic. We suggest its full potential in therapy may not have been reached. In this paper, we contrast 6-TG and the more widely used 6-mercaptopurine; discuss 6-TG metabolism, pharmacokinetics, dosage and schedule; and summarize many of the early studies that have shown infrequent but nevertheless positive results with 6-TG treatment of cancers. We also consider studies that suggest that combinations of 6-TG with other agents may enhance antitumor effects. Although not yet tested in man, 6-TG has recently been proposed to treat a wide variety of cancers with a high frequency of homozygous deletion of the gene for methylthioadenosine phosphorylase (MTAP), often codeleted with the adjacent tumor suppressor CDKN2A (p16). Among the cancers with a high frequency of MTAP deficiency are leukemias, lymphomas, mesothelioma, melanoma, biliary tract cancer, glioblastoma, osteosarcoma, soft tissue sarcoma, neuroendocrine tumors, and lung, pancreatic, and squamous cell carcinomas. The method involves pretreatment with the naturally occurring nucleoside methylthioadenosine (MTA), the substrate for the enzyme MTAP. MTA pretreatment protects normal host tissues, but not MTAP-deficient cancers, from 6-TG toxicity and permits administration of doses of 6-TG that are much higher than can now be safely administered. The combination of MTA/6-TG has produced substantial shrinkage or slowing of growth in two different xenograft human tumor models: lymphoblastic leukemia and metastatic prostate carcinoma with neuroendocrine features. Further development and a clinical trial of the proposed MTA/6-TG treatment of MTAP-deficient cancers seem warranted.

Thiopurines in inflammatory bowel disease revisited

Although a great variety of new drugs have been introduced for the therapy of inflammatory bowel diseases so far, a definite cure of the disease is still out of scope. An anti-inflammatory approach to induce remission followed by maintenance therapy with immunosupressants is still the mainstay of therapy. Thiopurines comprising azathioprine and its active metabolite mercaptopurine as well as tioguanine, are widely used in the therapy of chronic active inflammatory bowel disease (IBD). Their steroid sparing potential and efficacy in remission maintenance are out of doubt. Unfortunately, untoward adverse events are frequently observed and may preclude further administration or be life threatening. This review will focus on new aspects of thiopurine therapy in IBD, its efficacy and safety.

Prometheus: the Supreme Court redefines the patentability of diagnostic inventions

The United States Supreme Court recently issued an opinion regarding the patentability of claims directed to diagnostic methods in Mayo Collab. Service v. Prometheus Lab., Inc. In this opinion, the Supreme Court held that correlations between metabolite levels in the human body and either therapeutic efficacy or adverse effects are unpatentable laws of nature. It further found that a patent claim to a method including such a correlation is unpatentable if the remainder of the claim contains only conventional and well-known steps. The Prometheus decision creates uncertainty regarding the scope of patentable subject matter, particularly in the fields of diagnostic and personalized medicine, that will remain until future cases apply this new doctrine.

UVA photosensitization of thiopurines and skin cancer in organ transplant recipients

The thiopurines azathioprine, 6-mercaptopurine and 6-thioguanine (6-TG) are important medications for cancer and inflammatory disorders. They are also widely prescribed as immunosuppressants in organ transplant patients. Their metabolism results in the incorporation of 6-TG into patients' DNA, and this increases skin sensitivity to incident UVA. Unlike the canonical DNA bases, which do not absorb UVA to a significant degree, DNA 6-TG is a strong UVA chromophore. It acts as a Type II UVA photosensitizer, and the combination of 6-TG and UVA treatment induces a synergistic toxicity in cultured human cells. Here, we review some of the damage that this interaction causes. Photochemical activation of DNA 6-TG triggers DNA and protein oxidation; it induces DNA breakage, DNA crosslinking, oxidation of DNA bases and the covalent attachment of proteins to DNA. Many of these photochemical DNA lesions are difficult for cells to deal with, and we review the evidence linking thiopurine immunosuppression with genome instability and the high incidence of skin cancer in organ transplant recipients.

[Clinical characteristics of hepatic veno-occlusive disease in 6 children with hematologic neoplasm treated with 6-thioguanine]

OBJECTIVE

To improve the treatment of drug related childhood hepatic veno-occlusive disease (HVOD), clinical characteristics of 6 children with hematologic neoplasm from 2 hospitals of China Children's Leukemia Group (CCLG) treated with 6-thioguanine (6-TG) complicated with HVOD were analyzed.

METHOD

All the drug related HVOD patients were treated with CCLG acute lymphoblastic leukemia (ALL)-2008 protocol. They were from Children's Hospital of Fudan University and Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College from April 2008 to April 2009. The diagnosis was made according to the modified Seattle criteria and Baltimore criteria, including 2 or 3 of the following clinical features: hepatomegaly and upper right abdominal pain, jaundice (bilirubin ≥ 35 µmol/L), ascites or confirmed by pathology. The 6 HVOD patients' clinical manifestations, laboratory finding, imageologic and pathologic data were collected and analyzed.

RESULT

Of the 6 patients, 2 were males and 4 females. Mean age of the 6 patients was 3.89 years (range from 3 years 1 month to 4 years 11 months). The original disease was acute lymphoblastic leukemia. HVOD occurred during chemotherapy protocols of CAM (CTX + Ara-C + 6-TG) or maintenance period (MTX + 6-TG). Most of 6 HVOD patients presented with pain in liver area, hepatomegaly on imaging, elevated aminotransferase and bilirubin (often ≥ 35 µmol/L), hydroperitonia was common, one with pleural fluid, illegible hepatic veins. All the patients recovered after being treated with hepatoprotective, jaundice-relieving and supportive therapeutics, some patients were treated with low molecular weight heparin. The prognoses were good.

CONCLUSION

HVOD was a serious complication of chemotherapy with 6-TG. Hepatoprotective and jaundice-relieving and low molecular weight heparin could improve the prognosis.

Health-related quality of life of youth with inflammatory bowel disease: a comparison with published data using the PedsQL 4.0 generic core scales

BACKGROUND

This study compared youth and parent-proxy reports of health-related quality of life (HRQoL) among youth with inflammatory bowel disease (IBD) to published comparison group data and examined concordance between youth and parent-proxy reports of HRQoL.

METHODS

One hundred thirty-six youth and parent-proxy reports on the PedsQL 4.0 Generic Core Scales were compared to published data from chronically ill, acutely ill, and healthy comparison groups using independent samples t-tests. Reporter agreement was examined using paired samples t-tests and intraclass correlations (ICCs).

RESULTS

Youth with IBD reported lower psychosocial functioning than the healthy comparison group, higher physical and social functioning than the chronically ill group, and lower school functioning than all published comparison groups. Parent-proxy reports of youth HRQoL were higher than the chronically ill group, but lower than the healthy group on all scales except psychosocial functioning. Youth with active IBD reported lower physical health domain scores than youth with inactive disease. Concordance between youth and parent-proxy reports was moderate, with the lowest agreement in school and social functioning.

CONCLUSIONS

Youth with IBD and their parents rate HRQoL as lower than healthy youth but do not perceive the impact of IBD to be as limiting as in other chronic conditions. Youth report suggests that IBD may be particularly detrimental to HRQoL in the school functioning domain. Moderate agreement between parent and youth reports substantiates continued use of multiple informants in studies of pediatric HRQoL.

Phase II TPDCV protocol for pediatric low-grade hypothalamic/chiasmatic gliomas: 15-year update

To report long-term results for children with low-grade hypothalamic/chiasmatic gliomas treated on a phase II chemotherapy protocol. Between 1984 and 1992, 33 children with hypothalamic/chiasmatic LGGs received TPDCV chemotherapy on a phase II prospective trial. Median age was 3.0 years (range 0.3-16.2). Twelve patients (36%) underwent STRs, 14 (42%) biopsy only, and seven (21%) no surgery. Twenty patients (61%) had pathologic JPAs, nine (27%) grade II gliomas, and four (12%) no surgical sampling. Median f/u for surviving patients was 15.2 years (range 5.3-20.7); 20 of the 23 surviving patients had 14 or more years of follow-up. Fifteen-year PFS and OS were 23.4 and 71.2%, respectively. Twenty-five patients progressed, of whom 13 are NED, two are AWD, and 10 have died. All children who died were diagnosed and first treated at age three or younger. Age at diagnosis was significantly associated with relapse and survival (P = 0.004 for PFS and P = 0.037 for OS). No PFS or OS benefit was seen with STR versus biopsy/no sampling (P = 0.58 for PFS, P = 0.59 for OS). For patients with JPAs and WHO grade II tumors, the 15-year PFS was 18.8 and 22.2% (P = 0.95) and 15-year OS was 73.7 and 55.6% (P = 0.17), respectively. Upfront TPDCV for children with hypothalamic/chiasmatic LGGs resulted in 15-year OS of 71.2% and 15-year PFS of 23.4%. No survival benefit is demonstrated for greater extent of resection. Age is a significant prognostic factor for progression and survival.

Idarubicin plus behenoyl cytarabine and 6-thioguanine compares favorably with idarubicin plus cytarabine-based regimen for children with previously untreated acute myeloid leukemia: 10-year retrospective, multicenter study in Korea

We investigated the outcome of idarubicin plus N(4)-behenoyl-1-beta-D-arabinofuranosyl cytosine (BHAC)-based chemotherapy (BHAC group, n=149) compared to idarubicin plus cytarabine-based chemotherapy (cytarabine group, n=191) for childhood acute myeloid leukemia (AML). Between January 1996 and December 2005, 340 children with AML from 5 university hospitals in Korea received the BHAC-based or cytarabine-based chemotherapy, with or without hematopoietic stem cell transplantation. After induction therapy, 264 (77.6%) of 340 children achieved a complete remission (CR) and 43 (12%) achieved a partial remission (PR). The CR rate in the BHAC group was higher than in the cytarabine group (85.2% vs. 71.7%, P=0.004). However, the overall response rate (CR+PR) was not different between the two groups (93.3% vs. 87.9%, P=0.139). The 5-yr estimates of overall survival (OS) of children in the two groups were similar (54.9% for the BHAC group vs. 52.4% for the cytarabine group, P=0.281). Although the results were analyzed according to the treatment type and cytogenetic risk, the OS showed no significant difference between the BHAC group and the cytarabine group. In the present study, the clinical outcomes of the BHAC-based chemotherapy, consisting of BHAC, idarubicin, and 6-TG, are comparable to that of the cytarabine-based chemotherapy for childhood AML.

[Long-term observations of children with acute lymphoblastic leukemia and high leukocytosis treated according to modified "New York" protocols (1987-2003)]

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Due to new therapeutic schedules and cooperation between oncological centers it is curable in more than 80% of affected children. For the optimalization of the therapy there is necessary to assess the risk criteria that have influence on the treatment results in the certain groups of patients. Hyperleukocytosis and the age (less than 1 year and more than 10 years) are known as unfavorable risk factors. The study was designed to assess the long-term treatment results in children with ALL and the initial leukocytosis over 50 000/mm3 with the use of the modified "New York" protocols. We present the treatment results of 340 children with ALL treated in nine centers of Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) according to three consecutive versions of modified "New York" protocol (group I, II, and III) between 1987 and 2003. Within the analyzed groups the first complete remission (I CR) was achieved in 91%, 95% and 96% of the patients, respectively. Relapses occurred in 37%, 21.5% and 26% of the patients and 3.7%, 1.8% and 5.7% of children died in the I CR due to complications, in the I, II and III therapeutic group, respectively. Obtained 5-and 10-year event-free survival (EFS) were 56% and 53.5% for the group I and 73% and 73% for the group II. Five-year EFS for the group III was 67%. The implementation of the New York protocol in 1987 and New York I in 1997 has improved the treatment results in children with ALL and initial leukocytosis over 50 000/mm3. Protocol New York II did not further improve the treatment results. Among analyzed parameters (age, gender, the initial leukocytosis, the blast cells immunophenotype) only age had the statistical significance. The implementation of modified "New York" protocols has improved the treatment results in children with ALL and initial leukocytosis over 50 000/mm3 compared to previous results.

Busulfan, antimetabolites, radiotherapy, and cost of treatment in chronic myelocytic leukemia. A non-controlled, non-randomized monocenter study with historical controls

The possibilities were studied of achieving remission more quickly, of preventing conceivably alkylator-induced blastic transformation, and of prolonging survival in chronic myelocytic leukemia (CML) by replacing busulfan induction of remission by antimetabolite induction. The promise of the project was not considered to merit a prospective, controlled, randomized multicenter study, and therefore a retrospective, non-controlled, non-randomized pilot study was elected. One antimetabolite-treated group (cytosine arabinoside and thioguanine) and two busulfan-treated patient groups were studied. One of the latter two groups received splenic irradiation in addition to busulfan. No statistically significant differences between the busulfan groups were found in the time to achieve remission, the length of the first, unmaintained remission, the frequency of blastic metamorphosis or the cost of treatment. The actuarial survival curves of all three groups were similar. The antimetabolite induction was well tolerated and led to a statistically significantly more rapid remission than busulfan. However, the remission was significantly shorter, and no significant difference in the frequency of blastic metamorphosis was found between the groups. The median cost (from diagnosis to death) of hospitalization, visits, treatment, and part of the loss of production was approximately 106 000 Sw. cr. in the busulfan + radiotherapy group, 116 000 in the busulfan group, and 178 000 in the antimetabolite group. It is suggested that a prospective, randomized, controlled study could confirm that the present antimetabolite induction may lead to a more rapid remission induction in CML without more side-effects. However, to prevent early relapse, antimetabolite induction should be combined with busulfan maintenance treatment.

[Analysis of therapy results and prognostic factors in children with acute lymphoblastic leukaemia in Warmia and Mazury region: 17-years experience]

In the Warmia and Mazury region inhabited by 1.4 mln people, 6-16 new cases od childhood acute leukaemia are reported every year.

AIM

Analysis of treatment outcome and identification of prognostic factors in children treated for acute lymphoblastic leukaemia (ALL).

PATIENTS AND METHODS

A total number of 113 children aged 1.1-17.8 years (median age 5.5 years) were diagnosed for ALL in the Specialist Children Hospital of Olsztyn Province between 1991-2007. Children were treated in 6 consecutive protocols including 4 of the BFM group (Berlin-Frankfurt-Münster) and 2 of the modified American New York and New York II protocols. Probability of event-free survival (pEFS) was the principal indicator of effective of treatment in ALL.

RESULTS

Kaplan-Meier estimate of 17-year pEFS of all the 113 study patients was 0.72+/-0.05. The analysis of treatment results showed gradual improvement in the consecutive treatment protocols, including: pEFS=0.61+/-0.15 in the New York protocol; in the New York II - pEFS=0.76+/-0.15; in ALL-BFM-86 - pEFS=0,71+/-0,10; in ALL-BFM-90 - pEFS=0.79+/-0.08; in ALL-BFM-95 - pEFS=0.72+/-0.11. The protocol ALL-IC-2002 is ongoing. Prognostic factors for pEFS by univariate analysis were: male gender (p=0.003), age under 2 year (p=0.004), spleen enlargement (p=0.043), Hgb>10g/dl (p=0.025), WBC>100 G/L (p=0.007), FAB L2 (p<0.001), loss of weight p=0.022 and defects of eyesight (p=0.006) before the diagnosis of ALL, and HBV infection during the therapy (p=0.019). Independent risk factors by multivariate analysis were: male gender (p=0.005), age under 2 year (p=0.052), the spleen enlargement (p=0.028), WBC>100 G/L (p=0.007), FAB L2 (p=0.007), eyesight defects (p=0.009) before the diagnosis of ALL, and infection of HBV during the therapy (p=0.027).

CONCLUSIONS

Large progress has been made in the treatment of acute lymphoblastic leukaemia of childhood and adolescence over the analyzed period of 17 years. Treatment results for children with acute lymphoblastic leukaemia in Olsztyn Province are similar to the results in the Polish Paediatric Leukaemia/Lymphoma Study Group.

Risk factors for post-treatment hypogonadism in testicular cancer patients

OBJECTIVES

Testicular germ-cell cancer (TGCC) patients are at risk of developing hypogonadism but no risk factors have yet been defined.

METHODS

Blood was collected from 143 TGCC patients (after orchidectomy, prior to further therapy (T0) and 6, 12, 24, 36 and 60 months (T6, T12, T24, T36 and T60) after therapy). Biological hypogonadism (BH) was defined as: serum testosterone below 10 nmol/l and/or LH >10 IU/l; odds ratios (ORs) for BH with BH at T0, age, stage of disease, testicular characteristics, and androgen receptor polymorphism as predictors were calculated as well as the OR for developing BH post-treatment (one to two cycles of adjuvant chemotherapy (ACT) versus three to four cycles of higher dose chemotherapy (HCT) versus adjuvant radiotherapy (RT)).

RESULTS

HCT increased the OR for BH at T6 (OR 22, 95% confidence interval (CI) 4.4-118) and T12 (OR 5.8, 95% CI 1.5-22). RT increased the OR at T6 (OR 10, 95% CI 2.1-47) and at T12 (OR 3.9, 95% CI 1.1-14). Microlithiasis predicted BH at T0 (OR 11, 95% CI 1.2-112), T12 (OR 3.9, 95% CI 1.1-13), T24 (OR 3.0, 95% CI 1.0-8.8), T36 (OR 5.4, 95% CI 1.7-17) and T60 (OR 4.4, 95% CI 1.2-16). BH at T0 was a risk for BH at T6 (OR 53, 95% CI 19-145), T12 (OR 125, 95% CI 37-430), T24 (OR 88, 95% CI 26-300) and T36 (OR 121, 95% CI 32-460).

CONCLUSIONS

It is clinically relevant that BH at T0 and testicular microlithiasis were predictive factors for post-treatment BH. HCT and RT gave temporary BH.

Thiopurines in current medical practice: molecular mechanisms and contributions to therapy-related cancer

Thiopurines have diverse clinical applications and their long-term use as anti-rejection drugs in transplant patients has been associated with a significantly increased risk of various types of cancer. Although they are slowly being replaced by a new generation of non-thiopurine immunosuppressants, it is anticipated that their use in the management of inflammatory and autoimmune diseases will continue to increase. Therapy-related cancer will remain a potential consequence of prolonged treatment for these generally non-life-threatening conditions. Understanding how thiopurines contribute to the development of cancer will facilitate clinical decisions about the potential risks to patients of long-term treatment for chronic inflammatory disorders.

Thiopurine-induced liver injury in patients with inflammatory bowel disease: a systematic review

The mean prevalence of azathioprine (AZA) or 6-mercaptopurine (MP)-induced liver injury in patients with inflammatory bowel disease was approximately 3%, and the mean annual drug-induced liver disorder rate was only 1.4%. However, this low figure calculated from retrospective studies contrasts with a much higher incidence (>10%) reported by a prospective study. Thiopurine-induced hepatotoxicity can be grouped into three syndromes: hypersensitivity, idiosyncratic cholestatic reaction, and endothelial cell injury (with resultant raised portal pressures, veno-occlusive disease, or peliosis hepatis). A small percentage of patients present with a slight elevation of liver tests (LTs) that do not have clinical implications and LTs return to normal values during the follow-up, indicating that it is not always necessary to adjust the dose of the immunomodulator. However, when abnormalities in LTs are more marked, the dose of AZA/MP may be reduced 50%, with posterior clinical and analytical controls. With this strategy, LTs frequently normalize spontaneously, and the initial AZA/MP dose may be cautiously prescribed again. Thiopurines may induce an unusual severe cholestatic jaundice that may not regress but even progress despite thiopurine withdrawal. Therefore, these drugs should be completely withdrawn, and not only tapered, in those patients presenting clinically significant jaundice. Despite a lack of evidence that monitoring of LTs is necessary in patients receiving AZA/MP, routinely performed laboratory controls including LTs seem recommendable. However, the optimal monitoring schedule remains to be established. As long-term hepatotoxicity seems to be an unpredictable and potentially severe adverse drug reaction of 6-thioguanine, this drug should not be administered outside a clinical trial setting. (Am J Gastroenterol 2007;102:1518-527).

Extended thiopurine metabolite assessment during 6-thioguanine therapy for immunomodulation in Crohn's disease

The proposed metabolic advantage of 6-thioguanine (6-TG) is the direct conversion into the pharmacologically active 6-thioguaninenucleotides (6-TGN). The authors assessed metabolic characteristics of 6-TG treatment in patients with Crohn's disease (N = 7) on therapy with 20 mg 6-TG. 6-thioguanine-monophosphate (6-TGMP), 6-thioguanine-diphosphate (6-TGDP), and 6-thioguanine-triphosphate (6-TGTP) were measured by high-performance liquid chromatography analysis in erythrocytes. Thiopurine S-methyltransferase activity and total 6-TGN levels were determined by standard methods. High interindividual variance in metabolite measurements was observed. Main metabolites were 6-TGTP (median = 531 pmol/8 x 10(8) red blood cells) and 6-TGDP (median = 199 pmol/8 x 10(8) red blood cells). Traces of 6-TGMP (median = 39 pmol/8 x 10(8) red blood cells) and 6-TG (2 patients) could be detected. 6-TGN levels correlated with 6-TGTP levels (r = 0.929, P = .003) and with the sum of separate nucleotides (r = 0.929, P = .003). No correlations were established between TPMT activity (median = 13 pmol/h/10(7)) and 6-TG metabolites. The 1-step metabolism of 6-TG still leads to high interindividual variance in metabolite concentrations. Total 6-TGN level monitoring may suffice for clinical practice.

The quality of molecular response to chemotherapy is predictive for the outcome of AML1-ETO-positive AML and is independent of pretreatment risk factors

The outcome of 45 AML1-ETO-positive acute myeloid leukemia (AML) patients was analyzed with special emphasis on the quality of molecular response to therapy. Patients received double induction therapy, either 6-thioguanine, cytarabine, and daunorubicin (TAD9)/high-dose cytosine arabinoside plus mitoxantrone (HAM) or HAM/HAM, followed by consolidation therapy (TAD9) according to the AML-Cooperative group 92 trial (AMLCG92) and AML-Cooperative group 99 trial (AMLCG99). All cases underwent cytomorphological, cytogenetical and molecular genetic analyses. AML1-ETO transcript levels were quantitatively assessed at diagnosis and during follow-up by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The median reduction of initial AML1-ETO expression level was 4 log (range 0-5) after both induction and consolidation therapies. The quality of molecular response after induction as well as consolidation therapies had significant impact on the cumulative incidence of relapse (P=0.021 and P=0.001, respectively), event free survival (EFS: P=0.001 and P=0.001, respectively) and overall survival (OS: P=0.013 and P=0.014, respectively). HAM/HAM improved the molecular response to induction therapy (P=0.042) but after consolidation, no differences in molecular response were detectable between TAD9/HAM and HAM/HAM. Patient- or disease-related factors had no impact on the molecular response to induction or consolidation therapy. The current study demonstrates that quantification of AML1-ETO transcript levels is a powerful tool for prediction of prognosis that is independent of pretreatment risk factors, and may be helpful for directing therapeutic decisions in the future.

Gastroparesis in patients with inactive Crohn's disease: a case series

BACKGROUND

Few studies have described patients with foregut dysmotility in inflammatory bowel disease. The aim of this case series was to evaluate clinical characteristics of 5 patients with inflammatory bowel disease and symptoms and signs of upper gut dysmotility.

CASE PRESENTATIONS

We describe a series of four patients with Crohn's disease and one with indeterminate colitis who presented with severe symptoms and signs of gastroparesis. We reviewed medical records of all cases. Gastric emptying of a solid meal was assessed by scintigraphy. Small bowel enteroclysis, gastroduodenoscopy and colonoscopy with biopsies were performed to estimate the activity of the disease and to exclude organic obstruction. None of the patients had any signs of active inflammation or stricture. All of the patients had markedly delayed gastric emptying with a mean t 1/2 of 234 minutes (range 110-380 minutes; normal values 54-94 minutes).

CONCLUSION

Clinicians should consider impaired gastric emptying when evaluating patients with Crohn's disease and severe symptoms of upper gut dysmotility, which cannot be attributed to active inflammation or organic obstruction of the digestive tract. Symptoms in these patients are refractory to various therapeutic interventions including tube feeding and gastric surgery.

Efficacy and safety of 6-thioguanine in the management of inflammatory bowel disease

OBJECTIVE

6-Thioguanine has been used as an alternative immunomodulator in the treatment of inflammatory bowel disease but data on its efficacy and safety are limited. The aim of this study was to analyse our experience of the efficacy and safety of 6-thioguanine in inflammatory bowel disease.

MATERIAL AND METHODS

Patients attending the inflammatory bowel disease clinic who were started on 6-thioguanine therapy were included in this prospective observational study. Indications for initiating 6-thioguanine therapy and other related clinical, pharmacological and laboratory parameters prior to and during therapy were recorded to determine the efficacy and safety of 6-thioguanine.

RESULTS

A total of 40 patients were treated with 6-thioguanine, 28 with Crohn's disease, 10 with ulcerative colitis and 2 with indeterminate colitis, at a fixed daily dose of 40 mg and continued for a median duration of 34 weeks (range 2-90 weeks). The indications for 6-thioguanine therapy included previous clinical resistance to thiopurine analogues (n=21), intolerance to thiopurine analogues (n=8) and de novo 6-thioguanine use in steroid refractory disease (n=11). Disease remission was reached in 44%, 73% and 89% of these patient groups at 3, 6 and 12 months, respectively. Inflammatory markers and steroid use were significantly lower during 6-thioguanine therapy compared with in the period before therapy. Therapy was discontinued in 13 patients (33%), mainly because of thrombocytopenia and associated hepatotoxicity.

CONCLUSIONS

6-Thioguanine is a useful addition to treatment in inflammatory bowel disease but the frequent occurrence of hepatotoxicity limits its routine use.

Cytostatic drug treatment causes seeding of gene promoter methylation

Epigenetic changes in multiple genes are emerging as an important mechanism for tumour cells to acquire resistance to chemotherapy. In the present work, we test the hypothesis that epigenetic organisation in cancer cells can be affected by cytostatic drugs. Colorectal cancer cells were cultured for several weeks in the presence of 6-thioguanine. Bisulphite sequencing of the CpG-rich promoter regions of two expressed genes showed a significantly increased frequency of methylated CpG sites in drug-treated cells, as compared with controls: 4.7% and 1.7%, respectively, for the HPRT gene; and 11.1% and 8.2% for CDX1. Essentially, all of the increase for the CDX1 gene was in a four CpG sub-region previously found to correlate with gene activity (P = 0.006). This pattern of sparse promoter methylation fits with a recently proposed ‘seeding’ two-step mechanism leading up to gene inactivation in cancer cells. Taken together, our findings suggest activation in cancer cells of an epigenetic process enabling a tumour to generate drug-resistant variant cells.

Thioguanin-induced nodular regenerative hyperplasia of the liver-ROC analysis of different MR techniques

The aim of this study was to evaluate the diagnostic value of different magnetic resonance (MR) techniques for the diagnosis of nodular regenerative hyperplasia (NRH). Thirty-one patients with inflammatory bowel disease, who received 6-thioguanin, underwent liver biopsy and liver MRI on a 1.5-T MR system, with gadolinium and superparamagnetic iron oxide particles (SPIO). MR imaging (MRI) was evaluated independently as well as in consensus by two blinded readers, who received the following image sets: pre-contrast; pre-contrast and gadolinium-enhanced; pre-contrast and SPIO-enhanced and all images. The results were correlated with histopathology and diagnostic efficacy parameters were calculated. NRH was found in 13/31 patients. The set "all images" showed the highest sensitivity (84.6%), accuracy (77.4%) and negative predictive value (86.7%). However, results for gadolinium were only slightly inferior. The highest specificity (76.5%) was found for SPIO. The A(z) values of both readers were highest for gadolinium (mean A(z) = 0.824). It can be concluded that gadolinium-enhanced and SPIO-enhanced MRI enable an accurate diagnosis of NRH. Since gadolinium-enhanced MRI is very sensitive, it should be used for screening high-risk patients. SPIO-enhanced MRI is less sensitive, but more specific. The combination of both guarantees a high sensitivity and specificity and, therefore, is the diagnostic procedure of choice.

Oral outpatient chemotherapy medication errors in children with acute lymphoblastic leukemia

BACKGROUND

Although medication errors are 1 of the most common types of medical errors, their frequency in pediatric patients receiving oral outpatient chemotherapeutic agents is unknown. The prescribing, dispensing, and parental administration of these medications to children receiving treatment for acute lymphoblastic leukemia (ALL) were systematically reviewed to determine the rate and types of medication errors occurring in these patients.

METHODS

During a 2-month study period, parents of children with ALL were contacted and asked to participate in the study before a regularly scheduled clinic appointment. At the visit, the parent demonstrated how each medication was administered. A pediatric oncologist reviewed the medical record to determine the correct treatment regimen for study patients. After comparing the correct treatment regimen with what was administered, a classification of "no medication error," "medication error," or "cannot determine" due to insufficient information was made for each indicated drug. Identified medication errors were subclassified as prescribing, dispensing, or administration errors.

RESULTS

Data on 172 chemotherapeutic medications for 69 patients were analyzed. One or more errors occurred with 17 of the 172 (9.9%) medications; a classification of "cannot determine" was made for 12 (7.0%) medications. Among the 17 medication errors there were 12 (7.0%) administration errors and 5 (2.9%) prescribing errors. There were no pharmacy dispensing errors. All errors were due to incorrect dosing or failure to administer an indicated medication. At least 1 medication error occurred in 13 of the 69 (18.8%) study patients.

CONCLUSIONS

Prescribing and administration medication errors occurred with nearly 10% of chemotherapeutic drugs administered to outpatient children with ALL. Systematic changes, including computerized physician order entry and simplification of treatment protocols, should be considered.

Toxicity and efficacy of 6-thioguanine versus 6-mercaptopurine in childhood lymphoblastic leukaemia: a randomised trial

BACKGROUND

6-mercaptopurine has been a standard component of long-term continuing treatment for childhood lymphoblastic leukaemia, whereas 6-thioguanine has been mainly used for intensification courses. Since preliminary data have shown that 6-thioguanine is more effective than 6-mercaptopurine, we compared the efficacy and toxicity of the two drugs for childhood lymphoblastic leukaemia.

METHODS

Consecutive children with lymphoblastic leukaemia diagnosed in the UK and Ireland between April, 1997, and June, 2002, were randomly assigned either 6-thioguanine (750 patients) or 6-mercaptopurine (748 patients) during interim maintenance and continuing therapy. All patients received 6-thioguanine during intensification courses. We analysed event-free and overall survival on an intention-to-treat basis. We obtained toxicity data using an adverse-event reporting system, with follow-up questionnaires to seek detailed information for specific toxicities. This trial is registered with the International Standard Randomised Controlled Number 26727615 with the name ALL97.

FINDINGS

After a median follow up of 6 years, there was no difference in event-free or overall survival between the two treatment groups. Although 6-thioguanine conferred a significantly lower risk of isolated CNS relapse than did 6-mercaptopurine (odds ratio [OR] 0.53, 95% CI 0.30-0.92, p=0.02), the benefit was offset by an increased risk of death in remission (2.22, 1.20-4.14, p=0.01), mainly due to infections during continuing therapy. Additionally, 95 patients developed veno-occlusive disease of the liver. Of these, 82 were randomly assigned 6-thioguanine, representing 11% of all 6-thioguanine recipients. On long-term follow-up, about 5% of 6-thioguanine recipients have evidence of non-cirrhotic portal hypertension due to periportal liver fibrosis or nodular regenerative hyperplasia.

INTERPRETATION

Compared with 6-mercaptopurine, 6-thioguanine causes excess toxicity without an overall benefit. 6-mercaptopurine should remain the thiopurine of choice for continuing therapy of childhood lymphoblastic leukaemia.