Pharmacogenetics of methotrexate: toxicity among marrow transplantation patients varies with the methylenetetrahydrofolate reductase C677T polymorphism

A Rare Case of Acute Methotrexate Toxicity Leading to Bone Marrow Suppression

Methotrexate is a first-line disease modifying antirheumatic drug used for the treatment of inflammatory arthritis. Bone marrow suppression is a common adverse reaction of methotrexate following its long-term use. However, low dose methotrexate is rarely associated with life-threatening bone marrow suppression. This case represents an atypical presentation of acute bone marrow suppression shortly after initiating treatment with low-dose methotrexate. A 76-year-old male patient presented with oral ulcers, poor oral intake, and acute kidney injury within 3 weeks of initiating 15 mg weekly of methotrexate for seronegative rheumatoid arthritis. Complete blood count was suggestive of pancytopenia with hemoglobin of 10.8 g/dL, total white cell count 3.36 (1000/uL) (absolute neutrophil count 490 micro/L), platelets 19,000, serum albumin 3.1 g/dL, ESR elevated at 83 mm/hr, CRP elevated at 86.6 mg/L, and ferritin mildly elevated at 625 ng/mL. Peripheral blood smear showed signs of bone marrow suppression but no signs of hemolysis or inflammation. Serum methotrexate levels were minimally detectable at 0.05 umol/L. Methotrexate was held, within 48 hours of admission; his WBC dropped to 1.48, Hgb 9.9, and platelets 15,000. ANC reached a nadir of 220. He was treated with broad spectrum antibiotics, high-dose folic acid, fluconazole for oral thrush, and intravenous bicarbonate and leucovorin supplementation, dosed at PO 20 mg daily. On day 7, his blood count showed improvement along with improvement in his symptoms. The patient was discharged home on day 8th of hospitalization and upon one month follow-up in rheumatology clinic, his complete blood count had normalized. This case highlights multiple risk factors that triggered pancytopenia in our elderly patient, resulting in acute methotrexate toxicity.

Evaluation of cytogenetic and molecular markers with MTX-mediated toxicity in pediatric acute lymphoblastic leukemia patients

PURPOSE

Pediatric acute lymphoblastic leukemia (pALL) patients have better overall survival and methotrexate (MTX) is an effective drug used in their treatment. However, the treatment-related adverse effects (TRAEs) have a bigger impact on the therapy. In this study, we have evaluated the association of polymorphisms in genes encoding proteins engaged in MTX metabolism, and the cytogenetic aberrations with TRAEs.

METHODS

A total of 115 patients between the age of 1 and 18 years (average: 6.6) under maintenance therapy were selected for the study. SLC19A1 (c.80G > A), MTHFR (c.677C > T; c.1298A > C), and TYMS (c.*450_*455del) genotypes were determined using PCR techniques and Sanger sequencing. Cytogenetic and SNP findings were analyzed for any association with the reported toxicities using odds ratio, chi-square test, multifactor dimensionality reduction (MDR) analysis for synergistic effect and, multinomial logistic regression analysis for the likelihood of adverse events.

RESULTS

Among the evaluated genetic variations, SLC19A1 (c.80G > A) was significantly associated with TRAEs (OR = 5.71, p = 0.002). Multinomial logistic regression analysis (chi-sq = 16.64, p < 0.001) and MDR analysis (chi-sq = 10.51 p < 0.001) confirmed the finding. On the other hand, no significant association was observed between adverse events and any specific cytogenetic aberration.

CONCLUSION

SLC19A1 facilitates the import of cyclic dinucleotides and reduced folates, evaluating genotypes in this gene can help in better management of patients on methotrexate treatment. Assessing a broader gene panel can help in finding more associated markers and delivering personalized medicine to the patients.

The influence of MTHFR genetic polymorphisms on methotrexate therapy in pediatric acute lymphoblastic leukemia

MTHFR is a crucial enzyme in folate metabolism. This study aimed to determine the relationship between MTHFR genetic polymorphism and elimination and toxicities of methotrexate (MTX). To do that, the study enrolled 145 patients diagnosed with acute lymphoblastic leukemia, who received chemotherapy following the Chinese Children’s Cancer Group Acute Lymphoblastic Leukemia (CCCG-ALL)-2015 protocol (clinical trial number: ChiCTR-IPR-14005706). We analyzed the effects of MTHFR C677T and A1298C polymorphisms on MTX elimination and toxicities. Patients with the MTHFR C677T TT genotype could tolerate a significantly higher MTX dose than those with the CC/CT genotype. However, patients with C677T TT genotypes had an increased risk of hypokalemia (1.369 to CC and 1.409 to CT types). The MTX infusion rate in patients with the MTHFR A1298C AC genotype was slightly lower than that in those with CC or AA genotypes. Patients with the A1298C AA genotype had a 1.405-fold higher risk of hepatotoxicity than those with the AC genotype (P > 0.05). There was no significant difference between the prevalence of other toxicities among MTHFR C677T or A1298C genotypes (P > 0.05). Neither MTHFR C677T nor A1298C polymorphisms were significantly associated with delayed MTX clearance. To conclude, MTHFR polymorphisms were not good predictors of MTX-related toxicities.

Leucovorin Rescue After Methotrexate Graft-Versus-Host Disease Prophylaxis Shortens the Duration of Mucositis, Time to Neutrophil Engraftment, and Hospital Length of Stay

Oropharyngeal mucositis (OPM) is common following conditioning for allogeneic hematopoietic cell transplantation (alloHCT) and results in pain, functional status decline, need for nutritional support, infections, and prolonged length of stay (LOS). Methotrexate (MTX) graft-versus-host disease (GVHD) prophylaxis exacerbates OPM and slows hematopoietic engraftment, which may prolong LOS. Previous studies have demonstrated reduced OPM and more rapid engraftment when leucovorin (LCV) is added following MTX GVHD prophylaxis, yet this practice is controversial. The primary objective of this study was to determine if the routine addition of LCV to MTX GVHD prophylaxis impacted the duration of grade 2 to 4 OPM. Secondary objectives included determination of the incidence of grade 2 to 4 and grade 3 to 4 OPM, time to engraftment, ability to receive all four planned MTX doses, use of total parenteral nutrition (TPN), use of patient-controlled analgesia (PCA), LOS, incidence of acute or chronic GVHD, relapse-free survival (RFS), and overall survival (OS). This single-center, retrospective cohort study compared alloHCT outcomes for 46 adult patients who received MTX 15 mg/m² day +1; MTX 10 mg/m² days +3, +6, and +11 (15-10-10-10); and LCV following days +3, +6, and +11 MTX compared to historical controls who did not. Patients who received myeloablative conditioning (MAC) and matched related donor (MRD) or matched unrelated donor (MUD) alloHCT were included. The addition of LCV resulted in significant reductions in the duration of grade 2 to 4 OPM (median, 6 days versus 10.5 days; P = .0004), duration of TPN (7 days versus 16 days; P = .001), PCA use (16% versus 39%; P = .0001), time to neutrophil engraftment (median, 18 versus 20 days; P = .008), and LOS (median, 27.5 versus 31 days; P = .017) compared to historical controls. Patients who received routine LCV had similar incidences of grade 2 to 4 acute GVHD (30% versus 28%; relative risk [RR], 1.08; 95% confidence interval [CI], .57 to 2.03; P = 1.0), grade 3 or 4 acute GVHD (2% versus 7%; RR, .33; 95% CI, .04 to 3.09; P = .62) and chronic GVHD (37% versus 30%; RR, 1.21; 95% CI, .67 to 2.16; P = .66) compared to historical controls. Graft failure occurred in 2% of patients in each group. In a multivariable logistic regression analysis, RFS was similar in the LCV group compared to historical controls (HR, .86; 95% CI, .24 to 1.2; P = .13); however, OS was improved in patients who received LCV (HR, .33; 95% CI, .13 to .83; P = .01). In patients undergoing MAC MRD/MUD alloHCT with four planned doses of MTX GVHD prophylaxis (15-10-10-10), LCV was associated with reduced duration of grade 2 to 4 OPM, faster neutrophil engraftment, reduced utilization of TPN and PCA, and shortened LOS compared to historical controls not receiving routine LCV. These benefits were apparent without an increased risk of acute or chronic GVHD or adverse effect on RFS. LCV improved OS; however, it is unclear if this was due to the intervention or an unmeasured confounder. A randomized, prospective trial of LCV prophylaxis in patients receiving MAC alloHCT and MTX 15-10-10-10 GVHD prophylaxis is warranted to confirm our findings.

Influence of MTHFR C677T Polymorphism on High-Dose Methotrexate-Related Toxicity in Patients With Primary Central Nervous System Diffuse Large B-Cell Lymphoma

BACKGROUND

Primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL) is a relatively rare and aggressive neoplasm. High-dose methotrexate (HD-MTX) is an effective regimen for the treatment of PCNS-DLBCL, but MTX-related toxicity remains a problem. The aim of this analysis study was to investigate the influence of the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism on HD-MTX-related toxicity in patients with PCNS-DLBCL.

MATERIAL/METHODS

A prospective, observational study was conducted to analyze 148 MTX courses in 32 patients with PCNS-DLBCL.

RESULTS

The delayed MTX clearance was observed in 53 cycles (35.8%). The patients carrying the homozygous variant genotype had a higher risk of developing nephrotoxicity than those carrying the wild-type genotype (odds ratio [OR] 13.08; 95% confidence interval [CI], 1.65-103.86; P = .002) or heterozygous variant genotype (OR 8.43; 95% CI, 2.31-30.70; P < .001). Significant differences were observed in hepatotoxicity (OR 9.33; 95% CI, 2.54-34.27; P < .001) and hematologic toxicity (OR 3.09; 95% CI, 1.18-8.07; P = .024) in addition to nephrotoxicity between the homozygous variant genotype and the wild-type genotype.

CONCLUSION

The homozygous mutation of C to T at nucleotide 677 increases the risk on HD-MTX-related toxicity. The MTHFR C677T polymorphism can be used to predict HD-MTX-related toxicity for patients with PCNS-DLBCL.

Prediction of mucositis risk secondary to cancer therapy: a systematic review of current evidence and call to action

PURPOSE

Despite advances in personalizing the efficacy of cancer therapy, our ability to identify patients at risk of severe treatment side effects and provide individualized supportive care is limited. This is particularly the case for mucositis (oral and gastrointestinal), with no comprehensive risk evaluation strategies to identify high-risk patients. We, the Multinational Association for Supportive Care in Cancer/International Society for Oral Oncology (MASCC/ISOO) Mucositis Study Group, therefore aimed to systematically review current evidence on that factors that influence mucositis risk to provide a foundation upon which future risk prediction studies can be based.

METHODS

We identified 11,018 papers from PubMed and Web of Science, with 197 records extracted for full review and 113 meeting final eligibility criteria. Data were then synthesized into tables to highlight the level of evidence for each risk predictor.

RESULTS

The strongest level of evidence supported dosimetric parameters as key predictors of mucositis risk. Genetic variants in drug-metabolizing pathways, immune signaling, and cell injury/repair mechanisms were also identified to impact mucositis risk. Factors relating to the individual were variably linked to mucositis outcomes, although female sex and smoking status showed some association with mucositis risk.

CONCLUSION

Mucositis risk reflects the complex interplay between the host, tumor microenvironment, and treatment specifications, yet the large majority of studies rely on hypothesis-driven, single-candidate approaches. For significant advances in the provision of personalized supportive care, coordinated research efforts with robust multiplexed approaches are strongly advised.

Influence of plasma methotrexate level and MTHFR genotype in Korean paediatric patients with acute lymphoblastic leukaemia

Whether plasma MTX concentrations and MTHFR C677T and A1298C polymorphisms could be used as a predictor of occurrence of MTX-related toxicities in Korean paediatric patients with acute lymphoblastic leukaemia (ALL) were assessed. HD-MTX related toxicities, MTHFR polymorphisms and MTX plasma concentrations following 337 HD-MTX cycles to 117 children with ALL on maintenance therapy were analyzed. A significantly higher frequency of hyperbilirubinemia (P = 0.0443) and renal toxicity (P = 0.0107) were associated with high MTX concentrations by Fisher's exact test. Moreover, high MTX concentrations at 24 h, 48, and 72 h were significantly associated with increased frequency of vomiting (P < 0.05) and hyperbilirubinemia (P < 0.05) by Mann-Whitney U test. There was a significantly higher frequency of mucositis in patients with the MTHFR 677 TT genotype (P = 0.0273) and a significantly higher frequency of MTX dose reduction in patients with the 677 TT genotype (P = 0.0217), compared to the CC/CT genotype. Independently, plasma MTX concentrations and MTHFR C677T genotype could be useful markers for tailoring MTX dosing and monitoring adverse effects in childhood ALL HD-MTX therapy in Korean patients.

Polymorphisms of SLC19A1 80 G>A, MTHFR 677 C>T, and Tandem TS Repeats Influence Pharmacokinetics, Acute Liver Toxicity, and Vomiting in Children With Acute Lymphoblastic Leukemia Treated With High Doses of Methotrexate

Introduction: High dose methotrexate (HD-Mtx) is highly effective and significantly improves overall acute lymphoblastic leukemia (ALL) patients survival. The pharmacodynamics of Mtx depends on the polymorphism of genes encoding proteins engaged in the folate metabolism pathway. The aim of the current study is to determine the relationship between variants of folate metabolism-related genes and the frequency of acute toxicities of HD-Mtx. Material and Methods: A group of 133 patients aged 1.5-18.1 years (median: 6.3) was treated in accordance with the ALL-IC-2002 and ALL-IC-2009 protocols. The following polymorphisms were determined: 80 G>A SLC19A1 (solute carrier family 19 member 1; rs1051266) with direct DNA sequencing, as well as 677 C>T MTHFR (methylenetetrahydrofolate reductase; rs1801133) and the tandem repeats of the TS (thymidylate synthase) with PCR technique. HD-Mtx organ toxicities were evaluated based on the laboratory tests results and the National Cancer Institute criteria. Results: In patients with genotypes AA for SLC19A1 and CC or CT for MTHFR Mtx steady state concentrations (C_ss) and AUC_inf were distinctly higher. In patients with genotype 3R/3R for TS initial elimination rate constant was significantly higher (P = 0.003). Patients receiving Mtx at the dose of 5 g/m² had lower clearance (4.35 vs. 8.92 L/h/m²) as compared to the ones receiving 2 g/m² that indicates non-linear Mtx elimination at the higher dose. Liver impairment was the most frequently observed toxicity. The homozygous genotype was associated with a significantly higher incidence of hepatic toxicity for both the SLC19A1 (P = 0.037) and TS (P = 0.002). Logistic regression analysis indicated an increased risk of vomiting for the 2R/3R genotype of the TS gene (OR 3.20, 95% CI 1.33-7.68, P = 0.009) and for vomiting and hepatic toxicity for the 3R/3R genotype (vomiting: OR 3.39, 95% CI 1.12-10.23, P = 0.031; liver toxicity: OR 2.28, 95% CI 1.05-4.95, P = 0.038). None of the acute toxicities differed between the analyzed dosing groups. Conclusions: Determination of polymorphisms of SLC19A1, MTHFR, and TS genes might allow for a better prior selection of patients with higher risk of elevated Mtx levels. Our study is the first one to report the increased risk of hepatotoxicity and vomiting in patients with TS polymorphisms.

Pharmacogenetic Variants in MTHFR Gene are Significant Predictors of Methotrexate Toxicities in Bangladeshi Patients With Acute Lymphoblastic Leukemia

BACKGROUND

The objective of this pharmacogenetic study was to investigate the relationship of methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms with methotrexate (MTX)-induced toxicities and plasma homocysteine level in patients with acute lymphoblastic leukemia (ALL) from Bangladesh. Several polymorphisms result in reduced MTHFR activity that causes impaired remethylation of homocysteine to methionine and abnormal MTX metabolism, especially in tissues with high turnover. Therefore, the risk of elevated plasma homocysteine as well as MTX-induced toxicities become higher with MTHFR polymorphisms.

PATIENTS AND METHODS

We recruited 160 patients with ALL receiving MTX containing chemotherapeutic protocol, and they were genotyped for MTHFR C677T and A1298C polymorphisms with polymerase chain reaction-restriction fragment length polymorphism. We also measured the plasma homocysteine level of 51 patients by the AxSYM homocysteine assay method.

RESULTS

We found 68.1% CC, 26.3% CT, and 5.6% TT genotype for MTHFR C677T polymorphism and 39.3% AA, 46.9% AC, and 13.8% CC genotype for MTHFR A1298C polymorphism in patients with ALL. Our study suggested that MTX-induced mucositis and diarrhea are significantly associated with MTHFR C677T as well as MTHFR A1298C polymorphisms (P < .05).

CONCLUSION

The risk of elevated plasma homocysteine level was 5 to 6 times higher for both polymorphisms. This study may help to identify the patients who are at higher risk for MTX-related toxicities.

Genetic and clinical markers for predicting treatment responsiveness in rheumatoid arthritis

Although many drugs and therapeutic strategies have been developed for rheumatoid arthritis (RA) treatment, numerous patients with RA fail to respond to currently available agents. In this review, we provide an overview of the complexity of this autoimmune disease by showing the rapidly increasing number of genes associated with RA.We then systematically review various factors that have a predictive value (predictors) for the response to different drugs in RA treatment, especially recent advances. These predictors include but are certainly not limited to genetic variations, clinical factors, and demographic factors. However, no clinical application is currently available. This review also describes the challenges in treating patients with RA and the need for personalized medicine. At the end of this review, we discuss possible strategies to enhance the prediction of drug responsiveness in patients with RA.

Medicines associated with folate-homocysteine-methionine pathway disruption

Folate is vital for cell development and growth. It is involved in one-carbon transfer reactions essential for the synthesis of purines and pyrimidines. It also acts in conjunction with cobalamin (vitamin B₁₂) as a fundamental cofactor in the remethylation cycle that converts homocysteine to methionine. A deficiency in folate or vitamin B₁₂ can lead to elevated homocysteine level, which has been identified as an independent risk factor in several health-related conditions. Adequate folate levels are essential in women of childbearing age and in pregnant women, and folate deficiency is associated with several congenital malformations. Low folate levels can be caused by dietary deficiencies, a genetic predisposition or treatment with medicines that affect folate concentration. Women who are pregnant or of child-bearing age commonly use medicines, so it is important to identify the basic biochemical mechanisms by which medicines interfere with the folate-homocysteine-methionine pathway. This review focuses on prescription medicines associated with folate disruption. It also summarizes their undesirable/toxic effects. Recommendations regarding folate supplementation during medical therapy are also reviewed.

Influence of chemotherapeutic drug-related gene polymorphisms on toxicity and survival of early breast cancer patients receiving adjuvant chemotherapy

BACKGROUND

We investigated whether GSTT1 ("null" allele), GSTM1 ("null"allele), GSTP1 (A313G), RFC1 (G80A), MTHFR (C677T), TS (2R/3R) polymorphisms were associated with toxicity and survival in patients with early breast cancer (EBC) treated with adjuvant chemotherapy (CT).

METHODS

This prospective trial included patients with stage I-III BC subjected to CT with CMF or FEC regimens. PCR-RFLP was performed for MTHFR, RFC1 and GSTP1, while PCR for TS, GSTT1 and GSTM1 genes.

RESULTS

Among the 244 patients consecutively enrolled, 48.7% were treated with FEC and 51.3% with CMF. Patients with TS2R/3R genotype showed less frequently severe neutropenia (G3/G4) than those with TS2R/2R and 3R/3R genotype (p = 0.038). Patients with MTHFRCT genotype had a higher probability of developing severe neutropenia than those with MTHFR CC genotype (p = 0.043). Patients with RFC1GG or GSTT1-null genotype or their combination (GSTT1-null/RFC1GG) were significantly associated with a shorter disease free survival (DFS) (p = 0.009, p = 0.053, p = 0.003, respectively) and overall survival (OS) (p = 0.036, p = 0.015, p = 0.005, respectively). Multivariate analysis confirmed the association of RFC1GG genotype with a shorter DFS (p = 0.018) and of GSTT1-null genotype of a worse OS (p = 0.003), as well as for the combined genotypes GSTT1-null/RFC1GG, (DFS: p = 0.004 and OS: p = 0.003).

CONCLUSIONS

Our data suggest that TS2R/2R and 3R/3R or MTHFR CT genotypes have a potential role in identifying patients with greater risk of toxicity to CMF/FEC and that RFC1 GG and GSTT1-null genotypes alone or in combination could be important markers in predicting clinical outcome in EBC patients.

Identifying novel genes and biological processes relevant to the development of cancer therapy-induced mucositis: An informative gene network analysis

Mucositis is a complex, dose-limiting toxicity of chemotherapy or radiotherapy that leads to painful mouth ulcers, difficulty eating or swallowing, gastrointestinal distress, and reduced quality of life for patients with cancer. Mucositis is most common for those undergoing high-dose chemotherapy and hematopoietic stem cell transplantation and for those being treated for malignancies of the head and neck. Treatment and management of mucositis remain challenging. It is expected that multiple genes are involved in the formation, severity, and persistence of mucositis. We used Ingenuity Pathway Analysis (IPA), a novel network-based approach that integrates complex intracellular and intercellular interactions involved in diseases, to systematically explore the molecular complexity of mucositis. As a first step, we searched the literature to identify genes that harbor or are close to the genetic variants significantly associated with mucositis. Our literature review identified 27 candidate genes, of which ERCC1, XRCC1, and MTHFR were the most frequently studied for mucositis. On the basis of this 27-gene list, we used IPA to generate gene networks for mucositis. The most biologically significant novel molecules identified through IPA analyses included TP53, CTNNB1, MYC, RB1, P38 MAPK, and EP300. Additionally, uracil degradation II (reductive) and thymine degradation pathways (p = 1.06-08) were most significant. Finally, utilizing 66 SNPs within the 8 most connected IPA-derived candidate molecules, we conducted a genetic association study for oral mucositis in the head and neck cancer patients who were treated using chemotherapy and/or radiation therapy (186 head and neck cancer patients with oral mucositis vs. 699 head and neck cancer patients without oral mucositis). The top ranked gene identified through this association analysis was RB1 (rs2227311, p-value = 0.034, odds ratio = 0.67). In conclusion, gene network analysis identified novel molecules and biological processes, including pathways related to inflammation and oxidative stress, that are relevant to mucositis development, thus providing the basis for future studies to improve the management and treatment of mucositis in patients with cancer.

Methotrexate-induced pancytopenia: a case series of 46 patients

AIM

Methotrexate (MTX) has the potential to cause serious adverse reactions and even mortality. We analyzed the predisposing factors and outcome in patients with MTX-induced pancytopenia admitted into our unit from 1996 to 2015.

METHODS

Patients were identified by departmental database search. Pancytopenia was defined as white blood cell count (WBC) < 3500 cells/mm³ , hemoglobin (Hb) < 11 g/dL and platelet count < 150 000 cells/mm³ . Severe pancytopenia was defined as WBC < 2000 cells/mm³ , Hb < 10 g/dL and platelet count < 50 000 cells/mm³ .

RESULTS

Forty-six patients were included in the study (female = 35). Twenty-four had been under the care of either primary care physicians or orthopedic surgeons and presented to us with pancytopenia. Sixteen patients had severe pancytopenia. Disease distribution was as follows: rheumatoid arthritis 33, psoriasis eight, systemic sclerosis two and others three. The median dose of MTX was 10 mg/week and median duration of treatment was 11 months. The median cumulative dose was 750 mg. Symptoms at presentation included: oral mucositis (n = 37); fever (n = 24); diarrhea (n = 12), bleeding gums (n = 5) and purpura (n = 3). The potential risk factors were: hypoalbuminemia (n = 23), renal insufficiency (n = 14), dosing errors (n = 13) and non-supplementation of folates (n = 7). Thirteen patients died. WBC at admission was found to determine survival (P < 0.05).

CONCLUSION

In patients on MTX, oral mucositis and fever can herald pancytopenia. MTX-induced pancytopenia is associated with high mortality. WBC at admission is the most important prognostic factor. There is need for increased awareness among physicians to minimize prescribing errors. A national guideline on monitoring of patients on MTX is desirable.

Folate During Antifolate Chemotherapy: What We Know... and Do Not Know

The nutrient folate is essential for normal cell growth and development. Enzymes that require folate as a cofactor have been common targets for chemotherapeutic agents. Limited clinical guidance is available regarding optimal levels of dietary or supplemental folate intake during antifolate chemotherapy to meet the goals of minimizing treatment-related toxicity yet preserving treatment effectiveness. Patients with higher folate intake may experience less treatment-related toxicities; however, the concern is that folate may interfere with the effectiveness of the antifolate treatment and possibly support tumor growth. This article will review folate and antifolate metabolism and review the current body of knowledge regarding the interactions between folates and antifolates. Future research in this area should include evaluation of pretreatment folate status and dietary and supplemental folate intake before, during, and after treatment.

Presence of the methylenetetrahydrofolate reductase gene polymorphism MTHFR C677T in molar tissue but not maternal blood predicts failure of methotrexate treatment for low-risk gestational trophoblastic neoplasia

Gestational trophoblastic neoplasia (GTN) is a rare tumor, and its genomic constitution is different from the maternal genome because of its gestational origin. Methotrexate (MTX) is a standard chemotherapeutic agent for low-risk GTN. An association between polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene and MTX treatment outcome has been reported in various diseases. Thus, we examined the association between clinical outcome and MTHFR polymorphisms in both tumor and blood DNA of low-risk GTN patients. MTHFR C677T (rs1801133) and A1298C (rs1801131) were genotyped using high-resolution melting assays in 62 Japanese low-risk GTN patients and in 52 antecedent molar tissues. We compared the genotypes of MTHFR polymorphisms with the clinical outcome of 5-day MTX treatment. Twenty-five patients entered remission and 37 patients developed drug resistance or adverse effects that necessitated a drug change. The MTHFR 677T allele in molar tissue was significantly related to the need for drug change (P=0.006; odds ratio [OR], 3.13; 95% confidence interval [CI], 1.31-7.49), in contrast to MTHFR 1298C (P=0.18; OR, 0.63; 95% CI, 0.32-1.25). The MTHFR 677T and 1298C alleles obtained from patients' blood DNA were not related to MTX treatment outcome (P=0.49; OR 1.31; 95% CI, 0.61-2.91 and P=0.10; OR 0.52; 95% CI, 0.22-1.15, respectively). These data demonstrate for the first time that the genotype of MTHFR 677TT in molar tissue is associated with ineffective MTX treatment in Japanese low-risk GTN patients.

JAK2 Disease-Risk Variants Are Gain of Function and JAK Signaling Threshold Determines Innate Receptor-Induced Proinflammatory Cytokine Secretion in Macrophages

JAK2 genetic variants are associated with inflammatory bowel disease (IBD) and JAK inhibitors are being evaluated for therapy targeting immune-mediated diseases, including IBD. As JAK pathway-mediated cytokine regulation varies across cell types and stimulation conditions, we examined how JAK signaling and IBD-associated JAK2 variants regulate distinct acute and chronic microbial product exposure outcomes in human myeloid cells, consistent with the conditions of initial entry and ongoing intestinal tissue residence, respectively. Macrophages from controls and ulcerative colitis patients carrying the IBD-risk rs10758669 CC genotype showed increased JAK2 expression and nucleotide-binding oligomerization domain 2-induced JAK2 phosphorylation relative to AA carriers. Interestingly, the threshold of JAK2 expression and signaling determined pattern-recognition receptor (PRR)-induced outcomes; whereas anti-inflammatory cytokines progressively decreased with lower JAK2 expression, proinflammatory cytokines switched from decreased to increased secretion below a certain JAK2 expression threshold. Low JAK2-expressing rs10758669 AA macrophages were above this threshold; consequently, both PRR-induced pro- and anti-inflammatory cytokines were decreased. However, relative to rs10758669 CC risk carriers, AA carrier macrophages switched to increased nucleotide-binding oligomerization domain 2-induced proinflammatory cytokines at lower therapeutically used JAK inhibitor doses. Importantly, JAK inhibitors increased proinflammatory cytokines secreted by peripheral macrophages following chronic PRR stimulation and by human intestinal myeloid cells following exposure to intestinal pathogens. Mechanistically, the decreased response to and secretion of autocrine/paracrine IL-10, IL-4, IL-22 and thymic stromal lymphopoietin regulated these JAK-dependent outcomes in myeloid cells. Taken together, the JAK signaling threshold determines whether PRR-induced pro- and anti-inflammatory cytokines are reciprocally regulated in myeloid cells; consideration of JAK2 genotype and targeting of specific cell types might improve JAK-targeted therapy in immune-mediated diseases.

The Impact of Methylenetetrahydrofolate Reductase C677T Polymorphism on Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation with Methotrexate Prophylaxis

Pharmacogenomics can explain the inter-individual differences in response to drugs, including methotrexate (MTX) used for acute graft-versus-host disease (aGVHD) prophylaxis during hematopoietic stem cell transplantation (HSCT). In real-world practice, preplanned MTX dose is arbitrarily modified according to observed toxicity which can lead to unexpected and severe aGVHD development. We aimed to validate the influence of MTHFR C677T polymorphism on the outcomes of allogenic HSCT in a relatively under-represented homogenous Asian population. A total of 177 patients were divided into 677TT group versus 677C-carriers (677CT+677CC), and clinical outcomes along with baseline characteristics were analyzed and compared. Although there was a tendency towards increased peak liver function test results and accordingly greater delta values between the highest and the baseline in 677TT group, we found no associations between genotypes and hepatotoxicity. However, the incidence of acute liver GVHD (≥ grade 2) was significantly higher in the 677TT group than in the 677CC + 677CT group (P = 0.016). A total of 25 patients (14.1%) expired due to transplantation related mortality (TRM) during the first 180 days after HSCT. Patients carrying 677TT genotype were more likely to experience early TRM than 677C-carriers. The same pattern was observed in the cumulative TRM rate, and 677TT genotype patients were more prone to cumulative TRM (P = 0.010). This translated into shorter OS for patients with 677TT compared to 677C-carriers (P = 0.010). The 3-year survival after HSCT was 29.9% for 677TT cases and 47.1% for 677C-carriers. The multivariate analysis identified 677TT genotype (HR = 1.775. 95% CI 1.122–2.808, P = 0.014) and non-CR state (HR = 2.841. 95% CI 1.627–4.960, P<0.001) as predictors for survival. In conclusion, the MTHFR 677TT genotype appears to be associated with acute liver GVHD, and represent a risk factor for TRM and survival in patients undergoing HSCT with MTX as GVHD prophylaxis.

Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use

During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.

Mexican Childhood Acute Lymphoblastic Leukemia: A Pilot Study of the MDR1 and MTHFR Gene Polymorphisms and Their Associations with Clinical Outcomes

BACKGROUND

Genetic polymorphisms in patients with acute lymphoblastic leukemia (ALL) may influence the toxicity of chemotherapeutic agents. Due to the importance of the transport P-glycoprotein and methylenetetrahydrofolate reductase in the metabolism of chemotherapeutic agents, we analyzed the MDR1 rs1045642 and MTHFR rs1801133 polymorphisms and their associations with clinical outcomes in Mexican childhood ALL patients.

METHODS

A total of 109 patients participated in this study. The clinical evaluation consisted of a physical examination and a laboratory test. Genotyping of MDR1 rs1045642 (3435 C>T) and MTHFR rs1801133 (677 C>T) was performed by polymerase chain reaction/restriction fragment length polymorphism. Statistical analyses were performed using SPSS 14.0. The odds ratios and 95% confidence intervals (CI) were estimated by logistic regression.

RESULTS

Individuals who were CC homozygotes at MDR1 rs1045642 had lower risk of having methotrexate plasma concentrations >1 μM and leukopenia grade I (odds ratio [OR] = 0.30; 95% CI = 0.13-0.72 and OR = 0.32; 95% CI = 0.14-0.72, respectively). Patients who were CC homozygotes at MTHFR rs1801133 had a higher risk of developing mucositis (OR = 3.61; 95% CI = 1.42-9.14).

CONCLUSION

MDR1 rs1045642 and MTHFR rs1801133 should be considered as diagnostic candidates for the identification of pediatric patients with a high risk of suffering adverse events during ALL treatment.

Update on pathogenesis and predictors of response of therapeutic strategies used in inflammatory bowel disease

The search for biomarkers that characterize specific aspects of inflammatory bowel disease (IBD), has received substantial interest in the past years and is moving forward rapidly with the help of modern technologies. Nevertheless, there is a direct demand to identify adequate biomarkers for predicting and evaluating therapeutic response to different therapies. In this subset, pharmacogenetics deserves more attention as part of the endeavor to provide personalized medicine. The ultimate goal in this area is the adjustment of medication for a patient’s specific genetic background and thereby to improve drug efficacy and safety rates. The aim of the following review is to utilize the latest knowledge on immunopathogenesis of IBD and update the findings on the field of Immunology and Genetics, to evaluate the response to the different therapies. In the present article, more than 400 publications were reviewed but finally 287 included based on design, reproducibility (or expectancy to be reproducible and translationable into humans) or already measured in humans. A few tests have shown clinical applicability. Other, i.e., genetic associations for the different therapies in IBD have not yet shown consistent or robust results. In the close future it is anticipated that this, cellular and genetic material, as well as the determination of biomarkers will be implemented in an integrated molecular diagnostic and prognostic approach to manage IBD patients.

[Proton Pump Inhibitor and High-dose Methotrexate: Two Cases Reports]

Methotrexate (MTX) is a cytotoxic agent prescribed at high dose in treatment of malignancy. Association of MTX to proton pump inhibitor (PPI) is not recommended if doses are more than 20 mg per weeks and only to take into account for smaller doses. Review relate some cases of delayed elimination of methotrexate in patients taking PPI, which increase risk of toxic event. However, currently there is no status quo on interaction between PPI and MTX according to available data. We report two clinical cases illustrating one more time a toxic event to MTX in presence of PPI. In absence of risk/benefit ratio set correctly, an assessment of appropriateness of PPI prescription before MTX therapy can limit an iatrogenic risk.

CD34+ selection and the severity of oropharyngeal mucositis in total body irradiation-based allogeneic stem cell transplantation

OBJECTIVE

The purpose of the present study was to evaluate the impact of ex vivo T cell depleted (TCD) by CD34+ selection on the incidence and severity of oropharyngeal mucositis (OM) after myeloablative allogeneic stem cell transplant (allo-SCT) with total body irradiation (TBI) conditioning. This approach has the advantage of avoiding methotrexate for graft versus host disease (GVHD) prophylaxis.

PATIENTS AND METHODS

We analyzed the incidence and severity of OM in a cohort of 105 consecutive patients who underwent CD34+ selected (peripheral blood stem cells (PBSCs) from human leukocyte antigen (HLA)-identical siblings) allo-SCT with total body irradiation (TBI) conditioning. OM was graded by the World Health organization (WHO) and the Bearman regimen-related toxicity (RRT) scales.

RESULTS

The incidence of WHO grade 3-4 OM was 34.3 %. There were no cases of grade 3-4 OM by the RRT scale. Significant correlation was found between the severity of OM and the use of intravenous (IV) narcotic medications (r (2) = 0.15, p = 0.004), total parenteral nutrition (TPN; r (2) = 0.68, p < 0.001), and hospital length of stay (LOS) (r (2) = 0.12, p = 0.01).

DISCUSSION

TBI-induced OM can inflict significant morbidity in the early transplant period, and the incidence of WHO grade 3-4 OM can exceed 50 % when methotrexate is used for GVHD prophylaxis. In the CD34+ selected setting, methotrexate is avoided and the incidence of WHO grade 3-4 OM, use of TPN, and need for narcotic analgesia appear to be lower than historic evidence from standard T-replete allogeneic transplantation.

CONCLUSION

We conclude that toxicity from OM is tolerable in CD34+ selected allo-SCT and should be prospectively measured in randomized trials comparing CD34+ selection versus T-replete transplantation.

A case of recurrent pancytopenia in a patient with acute promyelocytic leukemia on maintenance chemotherapy and concomitant methyltetrahydrofolate reductase and thiopurine S-methyltransferase mutation - review of literature

Pharmacogenetics is a study of how genetic variation of an individual affects the drug response. We report a case of recurrent pancytopenia resulting from maintenance chemotherapy in a patient with acute promyelocytic leukemia and two pharmacogenetic mutations, namely, methylene tetrahydrofolate reductase C677T homozygous mutation and thiopurine methyltransferase mutation.

Pediatric perspective on pharmacogenomics

The advances in high-throughput genomic technologies have improved the understanding of disease pathophysiology and have allowed a better characterization of drug response and toxicity based on individual genetic make up. Pharmacogenomics is being recognized as a valid approach used to identify patients who are more likely to respond to medication, or those in whom there is a high probability of developing severe adverse drug reactions. An increasing number of pharmacogenomic studies are being published, most include only adults. A few studies have shown the impact of pharmacogenomics in pediatrics, highlighting a key difference between children and adults, which is the contribution of developmental changes to therapeutic responses across different age groups. This review focuses on pharmacogenomic research in pediatrics, providing examples from common pediatric conditions and emphasizing their developmental context.

Treatment of acute lymphoblastic leukemia from traditional chinese medicine

Acute lymphoblastic leukemia (ALL) is a cancer that immature white blood cells continuously overproduce in the bone marrow. These cells crowd out normal cells in the bone marrow bringing damage and death. Methotrexate (MTX) is a drug used in the treatment of various cancer and autoimmune diseases. In particular, for the treatment of childhood acute lymphoblastic leukemia, it had significant effect. MTX competitively inhibits dihydrofolate reductase (DHFR), an enzyme that participates in the tetrahydrofolate synthesis so as to inhibit purine synthesis. In addition, its downstream metabolite methotrexate polyglutamates (MTX-PGs) inhibit the thymidylate synthase (TS). Therefore, MTX can inhibit the synthesis of DNA. However, MTX has cytotoxicity and neurotoxin may cause multiple organ injury and is potentially lethal. Thus, the lower toxicity drugs are necessary to be developed. Recently, diseases treatments with Traditional Chinese Medicine (TCM) as complements are getting more and more attention. In this study, we attempted to discover the compounds with drug-like potential for ALL treatment from the components in TCM. We applied virtual screen and QSAR models based on structure-based and ligand-based studies to identify the potential TCM component compounds. Our results show that the TCM compounds adenosine triphosphate, manninotriose, raffinose, and stachyose could have potential to improve the side effects of MTX for ALL treatment.

MTHFR C677T polymorphism: association with lymphoid neoplasm and effect on methotrexate therapy

The aim of this study was to detect the possible role of methylene tetrahydrofolate reductase gene polymorphism (MTHFR C677T) in the pathogenesis of lymphoid neoplasms and to investigate the influence of this polymorphism on methotrexate toxicity in adult ALL patients treated with methotrexate maintenance therapy. There was a statistically significant increase in the risk of non-Hodgkin lymphoma in patients with CT genotype (OR, 2.9; 95% CI, 1.3-6.3; P = 0.007) and combined CT + TT genotype (OR, 3.2; 95% CI, 1.5-6.6; P = 0.006). While no significant association was found between this polymorphism and ALL risk. The patients with ALL treated with methotrexate during maintenance therapy were observed for signs of toxicity. MTHFR 677C>T polymorphism (CT + TT) was significantly overrepresented among cases with hepatic toxicity (OR = 15.6; 95% CI, 2.6-81.3; P = 0.001). In addition, they were overrepresented among cases with mucositis, anemia, thrombocytopenia, and leukopenia. However, it did not reach statistical significance level. Further studies on larger number of subjects are necessary. Additional studies on the role of MTHFR gene polymorphism with environment (folate intake) interaction are needed to confirm the role of these genetic polymorphisms.

Reduced intensity conditioning and oral care measures prevent oral mucositis and reduces days of hospitalization in allogeneic stem cell transplantation recipients

PURPOSE

Oral mucositis (OM) is a side effect of intensive chemotherapy and radiation and has been reported to affect 75-100% of hematopoietic stem cell transplantation (HSCT) recipients. The purpose of this study was to compare the incidence of OM in patients conditioned with myeloablative conditioning (MAC) to reduced-intensity conditioning (RIC) and to determine the effect of a new oral care protocol.

METHODS

The study involved 171 HSCT recipients, with hematological malignancies transplanted between 2007 and 2011. Median age of the patients was 50 years (range 12-71). Ninety-nine (58%) received RIC and 72 received MAC. Clinical features of OM were recorded from day -3 before to day +25 after HSCT using the World Health Organization (WHO) scoring system and the oral mucositis assessment score (OMAS).

RESULTS

Overall, 87% of the patients developed OM of any severity, which peaked on days 10-11. The mean WHO score was 1.7. In multivariate analysis, the severity of OM was associated with MAC (relative hazard (RH) 1.57, 95% confidence interval (CI) 1.37-1.80, p < 0.001), all donor-recipient gender combinations except female-to-male (RH = 1.26, 95% CI 1.10-1.4, p = 0.001), and early year of HSCT (RH = 0.84, 95%CI 0.7-0.96, p = 0.013). There was a correlation between long hospitalization and OM (day 15, r = 0.31, p < 0.001). There was a good correlation between the WHO and OMAS scoring systems for OM (r = 0.74, p < 0.001).

CONCLUSIONS

Oral mucositis was reduced in patients treated with RIC and in patients treated during recent years, when oral care was intensified. Increased scores of OM prolonged hospitalization.

Pharmacogenetics and pharmacogenomics in rheumatology

Pharmacogenetics and pharmacogenomics deal with possible associations of a single genetic polymorphism or those of multiple gene profiles with responses to drugs. In rheumatology, genes and gene signatures may be associated with altered efficacy and/or safety of anti-inflammatory drugs, disease-modifying antirheumatic drugs (DMARDs) and biologics. In brief, genes of cytochrome P450, other enzymes involved in drug metabolism, transporters and some cytokines have been associated with responses to and toxicity of non-steroidal anti-inflammatory drugs, corticosteroids and DMARDs. The efficacy of biologics may be related to alterations in cytokine, chemokine and FcγR genes. Numerous studies reported multiple genetic signatures in association with responses to biologics; however, data are inconclusive. More, focused studies carried out in larger patient cohorts, using pre-selected genes, may be needed in order to determine the future of pharmacogenetics and pharmacogenomics as tools for personalized medicine in rheumatology.

Pharmacogenomics and pharmacoepigenomics in pediatric medicine

In the past several years, human genetics studies have progressed from monogenic to complex and common diseases because of the advancement in technologies. There is increased knowledge of the pharmacokinetics and pharmacogenomics of the drugs in adults as well as in children. These technological developments provided new diagnostic, prognostic, and therapeutic opportunities. We are now in a position to address many additional ambitious questions. For instance, in clinical medicine, interindividual variation in drug response is a major problem. Some of the heterogeneity of drug safety and efficacy among individuals can be explained by pharmacogenomics. It has also the potential to improve the treatment in both adults and children. In pediatrics however, there is ontogeny and metabolic capacity in children is different compared to adults. Several specific developmental changes may underlie some of the variability in drug response seen in children. They may also be responsible for adverse drug reactions (ADRs). Therefore, much of the diversity in drug effects cannot be explained by studying the genomic diversity alone. It is necessary to include the effect of growth (involves variations in gene expression) along with genetic differences when explaining the variability in treatment response. In this respect epigenomics may expand the scope of pharmacogenomics towards optimization of drug therapy. Future studies must focus on periods of maturation of the drug-metabolizing enzymes and polymorphisms in their genes by using candidate gene approach, gene expression analysis, genome-wide haplotype mapping, and proteomics. The integration of genetic data and clinical phenotypes along with the role of other factors is necessary to evaluate both efficacy and ADRs of any drug. It may require extensive genetic epidemiological studies spanning over many years.

[Personalized medicine in rheumatology]

In rheumatology, especially in arthritides, early diagnosis and aggressive therapy may open up new dimensions of expectations, such as improvement of pain, prevention of structural, functional damage and better quality of life. Targeted (biological) therapy has brought new horizons in rheumatology. As it is a rather expensive treatment modality, it has been urgent to develop tools suitable for the prediction of therapeutic responses. Several clinical, immunological and genetic biomarkers have been established for this purpose. Among clinical markers, male sex, younger age, lower or even higher disease activity at baseline, combination treatment and quitting smoking may lead to better treatment outcome. Immunological biomarkers, such as C-reactive protein, seropositivity, peripheral blood or synovial cellular content have been associated with therapeutic responses. Finally, numerous genes or gene signatures may also predict the efficacy or safety of immunosuppressive drugs. Although sometimes there have been only few studies conducted that led to some controversy, some biomarkers have also been validated. This may lead us to optimism in terms of wider acceptance of personalized medicine in rheumatology.

Cancer pharmacogenomics in children: research initiatives and progress to date

Over the last few decades, cure rates for pediatric cancer have increased dramatically, and now over 80 % of children with cancer are cured of their disease. This improvement in cure has come with a significant cost, with many children suffering irreversible, life-threatening, or long-lasting toxicities due to the medications required during their treatment. In the last 2 decades, major technological advances in genomics and the mapping of the human genome have made it possible to identify genetic differences between children in order to investigate differing responses to cancer therapy and to help explain why children treated with the same medications can have different outcomes. The emerging field of pharmacogenomics has had many important findings in pediatric cancer. The focus of this review is drug toxicity in pediatric cancer and the use of pharmacogenomics to reduce these adverse drug reactions, with a specific focus on thiopurines, methotrexate, cisplatin, vincristine and anthracyclines. Future areas of research and the need for international collaboration are discussed.

Pharmacogenetic polymorphisms contributing to toxicity induced by methotrexate in the southern Spanish population with rheumatoid arthritis

Abstract Rheumatoid arthritis (RA) is a common illness of global significance for public health. Methotrexate (MTX) is the most broadly used disease-modifying antirheumatic drug for the treatment of RA, but it displays marked person-to-person variation in its propensity for toxicity. Several studies have suggested that polymorphisms in methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, reduced folate carrier (RFC1) G80A, and ABCB1 C3435T, could be related to methotrexate toxicity. This prospective study examined the different frequencies of MTHFR, RFC1, and ABCB1 pharmacogenetic variations between patients who have RA and those without RA. We also sought to assess the association between these polymorphisms and MTX toxicity. Four single-nucleotide polymorphisms (SNPs) were genotyped: C677T and A1298C from MTHFR, G80A from RFC1, and C3435T from ABCB1. The efficacy and toxicity of MTX were evaluated through clinical follow-up during 1 year of treatment. RA patients showed a higher frequency of the T allele at MTHFR C677T than patients without RA (p=0.049). There was a significant association between the presence of both the T allele at MTHFR C677T (p=0.006), and the C allele at ABCB1 C3435T (p=0.046), with toxicity development after 12 months of MTX treatment. However, there was no correlation between MTX toxicity and either the A allele at MTHFR A1298C or the G allele at RFC1 A80G. These data suggest that the presence of the MTHFR C677T and ABCB1 C3435T SNPs contribute to MTX toxicity in patients with RA. These observations contribute to a rapidly-growing knowledge base on the pharmacogenetics of RA and personalized medicine.

Diagnostic and therapeutic endoscopy in children and adolescents with cancer

Chemotherapy regimes in children with cancer often cause gastrointestinal side effects. Only limited data exist on the use of endoscopy in this group of patients.

METHODS

Retrospective review over a time period of 8.5 years identified 57 endoscopies (49 upper endoscopies, four colonoscopies, three sigmoidoscopies, one rectoscopy) in 38 patients (mean age 12.8 years). Seventeen children (45%) had hematological malignancies and 21 (55%) had solid tumors. In 12 children, platelet count was <50 × 10(9)/L and 10 children were neutropenic (ANC < 1 × 10(9)/L; absolute neutrophil count).

RESULTS

Forty diagnostic endoscopies, seven follow-up endoscopies, and 10 therapeutic endoscopies were performed. Biopsies were taken in 30 (75%) of 40 diagnostic endoscopies and microbiology samples in 17 (42.5%). Pathological findings identified in 33 (82.5%) diagnostic endoscopies: esophagitis 15 (37.5%)-two of them infections: 1 candida, 1 HSV (herpes simplex virus); Mallory-Weiss tears 5 (12.5%); gastritis 18 (45%; four Helicobacter pylori positive); ulcer 1 (2.5%); duodenitis 11 (27.5%); neoplasia 3 (7.5%); and colitis 5 (12.5%). Therapeutic endoscopies: Four PEG (percutaneous endoscopic gastrostomy) tube placements, one tube removal, two sclerotherapies for esophageal varices, three nasojejunal tubes for enteral nutrition (EN), and three additional tubes in primary diagnostic endoscopies.

COMPLICATIONS

One episode of fever (>38.5°C) after colonoscopy, one localized infection after PEG tube placement, and two episodes of temporary desaturation. No association of neutropenia with more infections was observed. No bleeding in thrombocytopenic patients was observed.

CONCLUSION

The data show that endoscopy in high-risk pediatric patients with malignant diseases is a safe procedure. Endoscopy reveals relevant information and have therapeutic impact with high probability. Tube placement techniques can help to maintain EN.

Suspected methotrexate toxicity from omeprazole: a case review of carboxypeptidase G2 use in a methotrexate-experienced patient with methotrexate toxicity and a review of the literature

We report a case of methotrexate toxicity potentially induced by a drug interaction between methotrexate and omeprazole in a 25-year-old man with osteosarcoma. The patient was placed on omeprazole after his first cycle of high-dose methotrexate for stress ulcer prophylaxis, and it was discontinued before the start of the first day of the patient's second round of high-dose methotrexate. The 24-hour methotrexate level was elevated and he continued to have sustained levels for 18 days. Side effects due to elevated serum methotrexate included seizures, mucositis, acute renal failure, and thrombocytopenia. Aggressive hydration, urinary alkalinization, and leucovorin were continued during the period of elevated methotrexate levels, with the patient receiving a course of hemodialysis and a dose of carboxypeptidase G2. The patient's symptoms resolved, and his renal function returned to baseline within 2 months. The patient was able to receive future courses of chemotherapy without methotrexate. Although use of the Naranjo adverse reaction probability scale indicated a probable relationship (score of 6) between the patient's development of methotrexate toxicity and omeprazole use, we believe this was a drug-drug interaction case consistent with previous reports in the literature.

Methylenetetrahydrofolate reductase polymorphisms, C677T and A1298C, are associated with methotrexate-related toxicities in Korean patients with rheumatoid arthritis

We investigated associations between the methylenetetrahydrofolate reductase (MTHFR) polymorphisms C677T and A1298C and methotrexate (MTX)-related toxicities in Korean patients with rheumatoid arthritis (RA) taking MTX. One hundred sixty-seven patients with RA were enrolled in a cross-sectional study and genotyped for the single-nucleotide polymorphisms C677T and A1298C in MTHFR. Alleles, genotypes, and haplotypes of the C677T and A1298C polymorphisms were not associated with specific MTX toxicities. However, among RA patients with the 1298CC genotype, the proportion who experienced at least one toxicity was significantly greater than the proportion of patients with 1298AA who did (P = 0.043). In addition, the proportion of patients with the 677C/1298A haplotype who experienced toxicity was greater than the proportion of those with 677C/1298C who did (P = 0.032, odds ratio = 2.085, 95% confidence interval 1.058-4.106). In this study, MTHFR polymorphisms were associated with MTX toxicities in Korean patients with RA. Further study for association of MTHFR polymorphisms with MTX toxicities should be needed in larger RA population.

Part 4: pharmacogenetic variability in anticancer pharmacodynamic drug effects

Response to treatment with anticancer drugs is subject to wide interindividual variability. This variability is expressed not only as differences in severity and type of toxicity, but also as differences in effectiveness. Variability in the constitution of genes involved in the pharmacokinetic and pharmacodynamic pathways of anticancer drugs has been shown to possibly translate into differences in treatment outcome. The overall knowledge in the field of pharmacogenetics has tremendously increased over the last couple of years, and has thereby provided opportunities for patient-tailored anticancer therapy. In previous parts of this series, we described pharmacogenetic variability in anticancer phase I and phase II drug metabolism and drug transport. This fourth part of a four-part series of reviews is focused on pharmacodynamic variability and encompasses genetic variation in drug target genes such as those encoding thymidylate synthase, methylene tetrahydrofolate reductase, and ribonucleotide reductase. Furthermore, genetic variability in other pharmacodynamic candidate genes involved in response to anticancer drugs is discussed, including genes involved in DNA repair such as those encoding excision repair crosscomplementing group 1 and group 2, x-ray crosscomplementing group 1 and group 3, and breast cancer genes 1 and 2. Finally, somatic mutations in KRAS and the gene encoding epidermal growth factor receptor (EGFR) and implications for EGFR-targeted drugs are discussed. Potential implications and opportunities for patient and drug selection for genotype-driven anticancer therapy are outlined.

Suspicion of drug-drug interaction between high-dose methotrexate and proton pump inhibitors: a case report - should the practice be changed?

We report a case of a potential drug-drug interaction in a woman treated by a first injection of high-dose methotrexate for a T-lymphoblastic lymphoma. Valaciclovir, fluoxetine and pantoprazole were given concomitantly. A methotrexate overdosage was shown at 36 h after infusion associated with a severe renal failure. Alkaline hyperhydration, folinic acid and carboxypeptidase G2 were given. Prescription analyses by pharmacists and literature research have permitted us to suggest that a drug-drug interaction between methotrexate and proton pump inhibitors (PPI) was responsible for this renal failure. Several mechanisms of interaction were suggested and might be related to the inhibition of renal methotrexate transporters by PPI, an increase in the methotrexate efflux to the blood by an upregulation of multidrug resistance protein 3 by PPI or genetic polymorphisms. This case shows that pharmacists can help physicians to optimize patient treatment: they consensually decided on the systematic discontinuation of PPI or a switch to ranitidine when patients were treated by high-dose methotrexate.