PURPOSE: We aimed to identify the impact of NUDT15 variants on thiopurine intolerance and 6-thioguanine nucleotide (6-TGN) levels in Korean children with acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: Genotyping of NUDT15 was tested in 258 patients with ALL registered at Samsung Medical Center. Patients were classified into normal-activity (wild-type), intermediate-activity (heterozygous variant), and low-activity groups (homozygous or compound heterozygous variant). Clinical and laboratory features during the first year of maintenance therapy were investigated. RESULTS: A total of 182 patients were included in the final analysis. There were five (2.7%), 46 (25.3%), and 131 (72.0%) patients in low-, intermediate-, and normal-activity groups, respectively. The lowest 6-mercaptopurine (6-MP) dose (mg/m2/day) was administered to the low-activity group (low-activity group 7.5 vs. intermediate-activity group 24.4 vs. normalactivity group 31.1, p < 0.01) from three months to a year after beginning maintenance therapy. The low-activity group experienced the longest duration of therapy interruption during the first year (low-activity group 169 days vs. intermediate-activity group 30 days vs. normal-activity group 16 days, p < 0.01). They also showed the lowest blood cell counts and had a longer duration of leukopenia (low-activity group 131 days vs. intermediate-activity group 92 days vs. normal-activity group 59 days, p < 0.01). 6-TGN level and its ratio to 6-MP dose were lowest in the low-activity group. CONCLUSION: NUDT15 variants cause hematopoietic toxicity with low 6-TGN levels. NUDT15 genotyping should be conducted before administering thiopurine, and dose adjustments require caution regardless of 6-TGN levels.
6-Mercaptopurine ; Blood Cell Count ; Child* ; Humans ; Leukemia ; Leukopenia ; Precursor Cell Lymphoblastic Leukemia-Lymphoma* ; Thioguanine

PURPOSE: Mercaptopurine (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 METHODS: Targeted 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. RESULTS: Using 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). CONCLUSION: We 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.
6-Mercaptopurine ; Alleles ; Computational Biology ; Cytochrome P-450 CYP1A1 ; Cytoprotection ; DNA Damage ; Genotype ; Humans ; Incidence ; Neutropenia* ; Pediatrics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma*

Various endocrine dysfunctions occur during chemotherapy, including hypoglycemia. However, reports of hypoglycemia associated with 6-mercaptopurine (6-MP) are rare. Herein, we report an 8-year-old boy with severe symptomatic hypoglycemia likely due to 6-MP during chemotherapy. He had been diagnosed with acute lymphoblastic leukemia 3 years previously and was in the maintenance chemotherapy period. Treatment included oral dexamethasone, methotrexate, and 6-MP, of which only 6-MP was administered daily. Hypoglycemic symptoms appeared mainly at dawn, and his serum glucose dropped to a minimum of 37 mg/dL. Laboratory findings showed nothing specific other than increased serum cortisol, free fatty acids, ketone, alanine aminotransferase, and aspartate aminotransferase. Under the hypothesis of hypoglycemia due to chemotherapy drugs, we changed the time of 6-MP from evening to morning and recommended him to ingest carbohydrate-rich foods before bedtime. Hypoglycemia improved dramatically, and there was no further episode during the remaining maintenance chemotherapy period. To the best of our knowledge, this is the first report of this type of hypoglycemia occurring in an Asian child including Korean.
6-Mercaptopurine* ; Alanine Transaminase ; Asian Continental Ancestry Group ; Aspartate Aminotransferases ; Blood Glucose ; Child* ; Dexamethasone ; Drug Therapy* ; Fatty Acids, Nonesterified ; Humans ; Hydrocortisone ; Hypoglycemia* ; Maintenance Chemotherapy ; Male ; Methotrexate ; Precursor Cell Lymphoblastic Leukemia-Lymphoma*

Extracolonic involvement of the gastrointestinal tract is extremely uncommon in ulcerative colitis (UC) and rarely found in the upper gastrointestinal tract or in postoperative cases since it typically responds to steroids. Here we report a case of UC complicated by extensive ileal inflammation that was refractory to steroids. A 20-year-old man was diagnosed with UC of typical pancolitis without ileal involvement and started treatment with pH-dependent mesalazine and oral prednisolone. Although his symptoms transiently resolved, the condition flared when the steroid dose was tapered down. Computed tomography revealed marked thickening of the ileal wall, and capsule endoscopy and balloon-assisted enteroscopy found diffuse mucosal inflammation with ulcers in the ileum. On the contrary, the inflammation in the colon and rectum was improving. Since the response to the second steroid course was inadequate, treatment with adalimumab and 6-mercaptopurine was initiated and finally achieved clinical and endoscopic remission. The investigation of small intestinal lesions is necessary in patients with UC whose clinical deterioration cannot be explained by colonic lesions.
6-Mercaptopurine ; Adalimumab* ; Capsule Endoscopy ; Colitis, Ulcerative* ; Colon ; Enteritis* ; Gastrointestinal Tract ; Humans ; Ileum ; Inflammation ; Inflammatory Bowel Diseases ; Mesalamine ; Prednisolone ; Rectum ; Steroids ; Ulcer* ; Upper Gastrointestinal Tract ; Young Adult

BACKGROUND: Thiopurine S-methyltransferase (TPMT) is an important enzyme in the metabolism of thiopurines including azathioprine (AZA), 6-mercaptopurine, and 6-thioguanine. TPMT genotyping is widely used for screening of AZA-related toxicity during routine clinical practice in Korea. However, the data of TPMT genotypes and its AZA-related toxicity have not been studied in the field of dermatology. OBJECTIVE: The aim of this study was to evaluate the genetic basis of TPMT polymorphism in Korean dermatologic patients and subsequently to investigate the relationship between mutant TPMT and adverse responses to AZA treatment. METHODS: This study was retrospective, single-center study. One hundred forty-nine Korean dermatologic patients who underwent TPMT screening test were included. Each patient's medical records, the result of TPMT screening test, dose and treatment period of AZA, and side effects, were reviewed. Laboratory tests were assessed at each visit in order to monitor adverse drug reactions. Leukopenia grading was used in accordance with the common terminology criteria for adverse events (CTCAE) ver. 4.03. RESULTS: Behçet's disease was the leading disorder among the patients. The frequency of TPMT mutation was 4.0% (6/149) among the participants in this study. Four of the six patients with genetic alterations were treated with a low-dose AZA regimen, but no AZA-related adverse events were observed. CONCLUSION: Our results suggest that 1) TPMT polymorphisms in Korean dermatologic patients are similar to those previously reported in Asian patients with the most common mutant allele being TPMT*3C and 2) AZA can be used in the patients with these polymorphisms under a careful dosing regimen.
6-Mercaptopurine ; Alleles ; Asian Continental Ancestry Group ; Azathioprine ; Behcet Syndrome ; Dermatology ; Drug-Related Side Effects and Adverse Reactions ; Genotype ; Humans ; Korea ; Leukopenia ; Mass Screening ; Medical Records ; Metabolism ; Retrospective Studies ; Thioguanine

Immunosuppressive agents and biological agents are widely used for therapy in patients with inflammatory bowel disease (IBD). However, these therapies may be associated with an increased risk of malignancy. There is evidence that exposure of the therapeutic agents such as thiopurine and anti-tumor necrosis factor for IBD is associated with an increased risk of lymphoproliferative disorders, skin cancers, or uterine cervical cancers. This article reviews the malignancies associated with the use of immunosuppressive agents and biological agents in IBD.
6-Mercaptopurine ; Azathioprine ; Biological Factors* ; Humans ; Immunologic Factors* ; Immunosuppressive Agents ; Inflammatory Bowel Diseases* ; Lymphoproliferative Disorders ; Necrosis ; Skin Neoplasms ; Tumor Necrosis Factor-alpha ; Uterine Cervical Neoplasms

BACKGROUND/AIMS: Recent genome-wide analyses have provided strong evidence concerning adverse events caused by thiopurine drugs such as azathioprine (AZA) and 6-mercaptopurine. The strong associations identified between NUDT15 p.Arg139Cys and thiopurine-induced leukopenia and severe hair loss have been studied and confirmed over the last 2 years. However, other coding variants, including NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, and FTO p.Ala134Thr, and a noncoding variation in RUNX1 (rs2834826) remain to be examined in detail in this respect. Therefore, we investigated the correlation between these adverse events and the 5 recently identified variants mentioned above among Japanese patients with inflammatory bowel diseases (IBD). METHODS: One hundred sixty thiopurine-treated patients with IBD were enrolled. Genotyping was performed using TaqMan SNP Genotyping Assays or Sanger sequencing. RESULTS: None of the 5 variants were associated with gastrointestinal intolerance to AZA. However, NUDT15 p.Arg139Cys was significantly associated with the interval between initiation and discontinuation of AZA among patients with gastrointestinal intolerance. This variant was strongly associated with early (<8 weeks) and late (≥8 weeks) leukopenia and severe hair loss. Moreover, it correlated with the interval between initiation of thiopurine therapy and leukopenia occurrence, and average thiopurine dose. NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, FTO p.Ala134Thr, and RUNX1 rs2834826 exhibited no significant relationship with the adverse events examined. CONCLUSIONS: Of the 5 variants investigated, NUDT15 p.Arg139Cys had the strongest impact on thiopurine-induced leukopenia and severe hair loss; therefore, its genotyping should be prioritized over that of other variants in efforts to predict these adverse events in Japanese patients with IBD.
6-Mercaptopurine ; Asian Continental Ancestry Group* ; Azathioprine ; Clinical Coding ; Hair ; Humans ; Inflammatory Bowel Diseases* ; Leukopenia

The aims of this study were to assess the risk of tuberculosis (TB) and the status of latent tuberculosis infection (LTBI) in Korean patients with inflammatory bowel disease (IBD) receiving tumor necrosis factor (TNF)-alpha blockers. We reviewed medical records of 525 Korean IBD patients (365 TNF-alpha blocker naive and 160 TNF-alpha blocker exposed) between January 2001 and December 2013. The crude incidence of TB was significantly higher in IBD patients receiving TNF-alpha blockers compared to TNF-alpha-blocker-naive patients (3.1% vs. 0.3%, P=0.011). The mean incidence of TB per 1,000 patient-years was 1.84 for the overall IBD population, 4.89 for TNF-alpha blocker users, and 0.45 for TNF-alpha-blocker-naive patients. The adjusted risk ratio of TB in IBD patients receiving TNF-alpha blocker was 11.7 (95% confidence interval, 1.36-101.3). Pulmonary TB was prevalent in patients treated with TNF-alpha blockers (80.0%, 4/5). LTBI was diagnosed in 17 (10.6%) patients, and none of the 17 LTBI patients experienced reactivation of TB during treatment with TNF-alpha blockers. Treatment with TNF-alpha blockers significantly increased the risk of TB in IBD patients in Korea. De novo pulmonary TB infection was more prevalent than reactivation of LTBI, suggesting an urgent need for specific recommendations regarding TB monitoring during TNF-alpha blocker therapy.
6-Mercaptopurine/adverse effects/analogs & derivatives/therapeutic use ; Adult ; Anti-Inflammatory Agents, Non-Steroidal/adverse effects/therapeutic use ; Antibodies, Monoclonal/adverse effects/therapeutic use ; Cohort Studies ; Colitis, Ulcerative/*drug therapy ; Crohn Disease/*drug therapy ; Female ; Humans ; Latent Tuberculosis/chemically induced/diagnosis/*epidemiology ; Male ; Mycobacterium tuberculosis/isolation & purification ; Republic of Korea ; Retrospective Studies ; Tuberculosis, Pulmonary/chemically induced/diagnosis/*epidemiology ; Tumor Necrosis Factor-alpha/*antagonists & inhibitors

The aims of this study were to assess the risk of tuberculosis (TB) and the status of latent tuberculosis infection (LTBI) in Korean patients with inflammatory bowel disease (IBD) receiving tumor necrosis factor (TNF)-alpha blockers. We reviewed medical records of 525 Korean IBD patients (365 TNF-alpha blocker naive and 160 TNF-alpha blocker exposed) between January 2001 and December 2013. The crude incidence of TB was significantly higher in IBD patients receiving TNF-alpha blockers compared to TNF-alpha-blocker-naive patients (3.1% vs. 0.3%, P=0.011). The mean incidence of TB per 1,000 patient-years was 1.84 for the overall IBD population, 4.89 for TNF-alpha blocker users, and 0.45 for TNF-alpha-blocker-naive patients. The adjusted risk ratio of TB in IBD patients receiving TNF-alpha blocker was 11.7 (95% confidence interval, 1.36-101.3). Pulmonary TB was prevalent in patients treated with TNF-alpha blockers (80.0%, 4/5). LTBI was diagnosed in 17 (10.6%) patients, and none of the 17 LTBI patients experienced reactivation of TB during treatment with TNF-alpha blockers. Treatment with TNF-alpha blockers significantly increased the risk of TB in IBD patients in Korea. De novo pulmonary TB infection was more prevalent than reactivation of LTBI, suggesting an urgent need for specific recommendations regarding TB monitoring during TNF-alpha blocker therapy.
6-Mercaptopurine/adverse effects/analogs & derivatives/therapeutic use ; Adult ; Anti-Inflammatory Agents, Non-Steroidal/adverse effects/therapeutic use ; Antibodies, Monoclonal/adverse effects/therapeutic use ; Cohort Studies ; Colitis, Ulcerative/*drug therapy ; Crohn Disease/*drug therapy ; Female ; Humans ; Latent Tuberculosis/chemically induced/diagnosis/*epidemiology ; Male ; Mycobacterium tuberculosis/isolation & purification ; Republic of Korea ; Retrospective Studies ; Tuberculosis, Pulmonary/chemically induced/diagnosis/*epidemiology ; Tumor Necrosis Factor-alpha/*antagonists & inhibitors

For decades, maintenance chemotherapy has failed to improve the cure rate or prolong the survival of patients with acute myeloid leukemia (AML), other than those with acute promyelocytic leukemia. Immediately after the first complete remission following consolidation therapy was obtained, oral maintenance chemotherapy (daily 6-mercaptopurine and weekly methotrexate) was given and continued for two years in transplant-ineligible AML patients. Leukemia-free survival (LFS) and overall survival (OS) were studied and compared between these patients and the historical control group who did not receive maintenance therapy. Consecutive 52 transplant-ineligible AML patients were analyzed. Among these patients, 27 received oral maintenance chemotherapy. No significant difference was found in the patients' characteristics between the maintenance and the control groups. The median OS was 43 (95% CI, 19-67) and 19 (95% CI, 8-30) months in the maintenance and the control groups, respectively (P = 0.202). In the multivariate analysis, the presence of maintenance therapy was an independent prognostic factor for better OS (P = 0.021) and LFS (P = 0.024). Clinical benefit from maintenance chemotherapy was remarkable in older patients (> or = 60 yr) (P = 0.035), those with intermediate or unfavorable cytogenetics (P = 0.006), those with initial low blast count in peripheral blood (P = 0.044), and those receiving less than two cycles of consolidation therapy (P = 0.017). Maintenance oral chemotherapy as a post-remission therapy can prolong the survival of patients with AML who are not eligible for transplantation, particularly older patients, those with intermediate or unfavorable cytogenetics, those with initial low blast count, and those receiving less than two cycles of consolidation therapy.
6-Mercaptopurine/*therapeutic use ; Adolescent ; Adult ; Aged ; Antimetabolites, Antineoplastic/*therapeutic use ; Antineoplastic Combined Chemotherapy Protocols/*therapeutic use ; Cytarabine/therapeutic use ; Disease-Free Survival ; Female ; Humans ; Idarubicin/therapeutic use ; Leukemia, Myeloid, Acute/*drug therapy/mortality ; Maintenance Chemotherapy/*methods ; Male ; Methotrexate/*therapeutic use ; Middle Aged ; Remission Induction ; Treatment Outcome ; Young Adult