Impact of novel polymorphisms related to cytotoxicity of cytarabine in the induction treatment of acute myeloid leukemia.

Several novel single nucleotide polymorphisms (SNPs) involved in cytarabine cytotoxicity and related to clinical outcomes have been reported recently in a series of 232 pediatric patients with acute myeloid leukemia (AML). We report the first adult AML cohort in which the influence of these SNPs in cytarabine efficacy and toxicity was analyzed. Six of polymorphisms with clinical significance in the previous study [rs12036333, rs10758713, rs9883101, rs6550826, IRX2: rs2897047, mutated in colorectal cancers (MCC): rs7729269] were analyzed in a cohort of 225 adult patients at initial diagnosis of AML treated with an induction scheme of idarubicin plus cytarabine. The variant alleles of rs12036333 and rs10758713 confirmed the previous associations with lower survival rates. The minor alleles of rs9883101 and rs6550826 were also related to lower survival, in concordance with higher cytarabine-induced cytotoxicity observed in pediatric patients. However, discordant findings between AML adult and pediatric population were observed with IRX2 rs2897047, showing higher survival in heterozygous genotype carriers. The heterozygous genotype of MCC rs7729269 was associated with higher cytarabine-induced toxicities (renal, hepatic, lung, skin toxicities), whereas lower time to thrombocytopenia recovery was associated with the MCC rs7729269 minor allele. This study confirms the influence in survival rates of these polymorphisms in an adult AML population. Novel associations between MCC SNPs and cytarabine toxicities were reported and should be validated in prospective studies involving larger groups of patients.

Impact of Single Nucleotide Polymorphisms (SNPs) on Immunosuppressive Therapy in Lung Transplantation.

Lung transplant patients present important variability in immunosuppressant blood concentrations during the first months after transplantation. Pharmacogenetics could explain part of this interindividual variability. We evaluated SNPs in genes that have previously shown correlations in other kinds of solid organ transplantation, namely ABCB1 and CYP3A5 genes with tacrolimus (Tac) and ABCC2, UGT1A9 and SLCO1B1 genes with mycophenolic acid (MPA), during the first six months after lung transplantation (51 patients). The genotype was correlated to the trough blood drug concentrations corrected for dose and body weight (C0/Dc). The ABCB1 variant in rs1045642 was associated with significantly higher Tac concentration, at six months post-transplantation (CT vs. CC). In the MPA analysis, CT patients in ABCC2 rs3740066 presented significantly lower blood concentrations than CC or TT, three months after transplantation. Other tendencies, confirming previously expected results, were found associated with the rest of studied SNPs. An interesting trend was recorded for the incidence of acute rejection according to NOD2/CARD15 rs2066844 (CT: 27.9%; CC: 12.5%). Relevant SNPs related to Tac and MPA in other solid organ transplants also seem to be related to the efficacy and safety of treatment in the complex setting of lung transplantation.

Genotype and allele frequencies of drug-metabolizing enzymes and drug transporter genes affecting immunosuppressants in the Spanish white population.

Interpatient variability in drug response can be widely explained by genetically determined differences in metabolizing enzymes, drug transporters, and drug targets, leading to different pharmacokinetic and/or pharmacodynamic behaviors of drugs. Genetic variations affect or do not affect drug responses depending on their influence on protein activity and the relevance of such proteins in the pathway of the drug. Also, the frequency of such genetic variations differs among populations, so the clinical relevance of a specific variation is not the same in all of them. In this study, a panel of 33 single nucleotide polymorphisms in 14 different genes (ABCB1, ABCC2, ABCG2, CYP2B6, CYP2C19, CYP2C9, CYP3A4, CYP3A5, MTHFR, NOD2/CARD15, SLCO1A2, SLCO1B1, TPMT, and UGT1A9), encoding for the most relevant metabolizing enzymes and drug transporters relating to immunosuppressant agents, was analyzed to determine the genotype profile and allele frequencies in comparison with HapMap data. A total of 570 Spanish white recipients and donors of solid organ transplants were included. In 24 single nucleotide polymorphisms, statistically significant differences in allele frequency were observed. The largest differences (>100%) occurred in ABCB1 rs2229109, ABCG2 rs2231137, CYP3A5 rs776746, NOD2/CARD15 rs2066844, TPMT rs1800462, and UGT1A9 rs72551330. In conclusion, differences were recorded between the Spanish and other white populations in terms of allele frequency and genotypic distribution. Such differences may have implications in relation to dose requirements and drug-induced toxicity. These data are important for further research to help explain interindividual pharmacokinetic and pharmacodynamic variability in response to drug therapy.

Meta-analysis and systematic review of the effect of the donor and recipient CYP3A5 6986A>G genotype on tacrolimus dose requirements in liver transplantation.

OBJECTIVE: A meta-analysis was carried out of published studies on the effect of the CYP3A5 6986A>G polymorphism in liver donors and transplant recipients on tacrolimus pharmacokinetics. METHODS: Cohort studies that evaluated the relationship between the CYP3A5 polymorphism in liver donors and transplant recipients and tacrolimus, trough blood concentration normalized for the daily dose (C) per kilogram body weight (D) (C/D, ng/ml/mg/kg/day) up to 1 year after transplantation, were included. Data were not restricted by patient age or the language or journal of publication. A literature search was conducted using the Cochrane Library, MEDLINE, EMBASE, and grey literature, and articles published up to 24 April 2013 were selected. Data were pooled (random-effects model), and the results were expressed as the mean difference of the corresponding C/D ratios and 95% confidence intervals. RESULTS: Six studies involving donor genotypes (254 patients) and four involving recipient genotypes (180 patients) were ultimately included. The meta-analysis showed the C/D ratio to be significantly higher in recipients with nonexpresser donor variants at all time points. In recipients, the variant did not influence the C/D ratio. CONCLUSION: The presence of the CYP3A5 6986A>G polymorphism in the donor affects tacrolimus pharmacokinetics in the recipient, although only the evidence available for the first month after transplantation was of adequate quality for demonstrating a significant difference. The evidence provided here shows no effect of the recipient genotype; however, the quality of the evidence was low, thereby precluding the drawing of firm conclusions.

Increased hospital stay and allograft dysfunction in renal transplant recipients with Cyp2c19 AA variant in SNP rs4244285.

Pharmacogenetics correlates certain genetic variants, such as single nucleotide polymorphisms (SNPs), with blood drug levels, efficacy, and adverse effects of the treatment. Tacrolimus is mainly metabolized via CYP3A4/5, whereas CYP2C19 and CYP3A4/5 are responsible for omeprazole metabolism. Omeprazole inhibits tacrolimus metabolism via CYP3A5 in patients carrying variant alleles of CYP2C19, increasing tacrolimus blood concentrations. Seventy-five renal transplant recipients treated with tacrolimus and concomitant omeprazole were genotyped in a panel of 37 SNPs with use of Sequenom MassArray. The patients with CYP2C19*2/*2 genotype (n = 4) showed a median posttransplantation hospital stay of 27.5 days (95% confidence interval [CI], 23-39 days), compared with 12 days (95% CI, 10-15 days) in patients with CYP2C19*1/*1 or CYP2C19*1/*2 (n = 71; P = 0.016, Kruskal-Wallis test).The difference in hospital stay was directly correlated with an increase in tacrolimus levels (C(min)/[dose/weight]) during the first week after trasplantation (in 59 patients with data on levels; P = 0.021, Kruskal-Wallis), excluding the patients with atypical metabolisms due to CYP3A5*1/*3 or CYP3A5*1/*1 genotype. Recipients with CYP2C19*2/*2 genotype also showed allograft delayed function (acute tubular necrosis in 3 patients). Genotyping of CYP3A5 and CYP2C19 in renal transplantation should be considered to be of interest when treating with tacrolimus and omeprazole, because CYP2C19*2/*2 variant indirectly elicits an increase of tacrolimus blood levels and, in our study population, the adverse effects described.

In utero exposure to mycophenolate mofetil: a characteristic phenotype?

Mycophenolate mofetil (MMF) is a widely prescribed immunosuppressive agent after solid organ transplantation. Potential teratogenic effects after in utero exposure to MMF in experimental studies and clinical observations in humans has been postulated in recent literature. However, a specific pattern of malformation has not been identified yet. We present a newborn patient, born to a recipient of renal transplantation, who became pregnant while taking MMF as immunosuppressive therapy. The newborn exhibited cleft lip and palate, bilateral microtia and atretic external auditory canals, chorioretinal coloboma, hypertelorism, and micrognathia. An extensive review of the literature documented six other cases with similar malformations after in utero exposure to MMF. A consistent pattern of malformations comprising cleft lip and palate, microtia and external auditory canals could be observed in five of the six cases. A different malformative pattern observed in one of the patients could be attributed to a different agent rather than MMF. The possible teratogenic effects of other immunosuppressive drugs, such as tacrolimus and prednisone, to which this patient was also exposed, are discussed herein. In addition, the differential diagnosis with other dysmorphic syndromes that can present with a similar phenotype, such as CHARGE syndrome, 18q deletion and hypertelorism-microtia-clefting (HMC) syndrome, is presented. We conclude that in utero exposure to MMF can cause a characteristic phenotype and propose the existence of a mycophenolate-associated embryopathy whose main features are: cleft lip and palate, microtia with atresia of external auditory canal, micrognathia and hypertelorism. Ocular anomalies, corpus callosum agenesis, heart defects, kidney malformations, and diaphragmatic hernia may be part of the phenotypic spectrum of MMF embryopathy. The human teratogenicity of MMF is reinforced by this report, and the current contraceptive recommendations about its use in fertile women are stressed.

Mycophenolate mofetil embryopathy: A newly recognized teratogenic syndrome.

Mycophenolate mofetil (MMF) is probably the most common employed immunosuppressant drug in recipients of solid organ transplant and in many autoimmune diseases. In vitro studies, a significant number of single clinical observations and a recent study from a group of different European teratogen information services, have provided very consistent data supporting the existence of a specific MMF embryopathy. The typical malformative pattern of MMF embryopathy includes external ear anomalies ranging from hypoplastic pinna (microtia) to complete absence of pinna (anotia); cleft lip, with or without cleft palate, and ocular anomalies as iris or chorioretinal coloboma and anophthalmia/microphthalmia. Other less frequent features are congenital heart defects, distal limbs anomalies, esophageal atresia, vertebral malformations, diaphragmatic hernia, and kidney and central nervous system anomalies. Neurodevelopmental outcome seems favorable in the small number of patients where information about this issue is available, but neurological deficits have been documented. Physicians in charge of women under MMF therapy should be aware of the potential risk of this drug to cause a specific embryopathy and the need of interrupting the treatment at least six weeks before becoming pregnant.

Serum Adalimumab Levels Predict Successful Remission and Safe Deintensification in Inflammatory Bowel Disease Patients in Clinical Practice.

BACKGROUND: Little is known about the association between the pharmacokinetic features of adalimumab (ADL) and disease outcome in patients with inflammatory bowel disease (IBD). AIMS: To assess the association between random serum ADL levels and clinical or biochemical remission with clinical decision making in daily practice according to these levels; and to determine the cutoff value for successful dose reduction in patients with IBD treated with ADL. METHODS: We conducted a prospective observational study of patients with IBD who received long-term maintenance therapy with ADL. RESULTS: Data were available for 157 serum samples from 87 patients. Serum ADL levels were associated with clinical remission: median 9.2 versus 6.0 µg/mL for patients with Crohn's disease with active disease (P = 0.009) and 14.4 versus 5.2 µg/mL in patients with ulcerative colitis with active disease (P = 0.002). Serum ADL levels were 9.2 µg/mL for patients with a normal C-reactive protein value (<5 mg/L) and 5.2 µg/mL for patients with a high C-reactive protein value (P = 0.002). ADL levels were significantly associated with normal fecal calprotectin value (<80 ng/g) (10.8 versus 7.6 µg/mL, respectively, P = 0.038). Serum ADL levels were significantly associated with successful deintensification, over a 6-month period of clinical follow-up, compared with the group in which doses remained unchanged (area under the curve 0.88; 95% confidence interval, 0.81-0.95; P < 0.001), with a cutoff value for successful deintensification of 12.2 µg/mL. CONCLUSIONS: Higher ADA levels were significantly associated with clinical and biochemical remission. Our results, which were obtained under conditions of daily clinical practice, suggest that an ADL cutoff of 12.2 µg/mL could be appropriate for successful dose reduction in patients with IBD treated with ADL.

Influence of cytarabine metabolic pathway polymorphisms in acute myeloid leukemia induction treatment.

Cytarabine is considered the most effective chemotherapeutic option in acute myeloid leukemia (AML). The impact of 10 polymorphisms in cytarabine metabolic pathway genes were evaluated in 225 adult de novo AML patients. Variant alleles of DCK rs2306744 and CDA rs602950 showed higher complete remission (p = .024, p = .045), with lower survival rates for variant alleles of CDA rs2072671 (p = .015, p = .045, p = .032), rs3215400 (p = .033) and wild-type genotype of rs602950 (p = .039, .014). Induction death (p = .033) and lower survival rates (p = .021, p = .047) were correlated to RRM1 rs9937 variant allele. In addition, variant alleles of CDA rs532545 and rs602950 were related to skin toxicity (p = .031, p = .049) and mucositis to DCK rs2306744 minor allele (p = .046). Other toxicities associated to variant alleles were hepatotoxicity to NT5C2 rs11598702 (p = .032), lung toxicity (p = .031) and thrombocytopenia to DCK rs4694362 (p = .046). This study supports the interest of cytarabine pathway polymorphisms regarding efficacy and toxicity of AML therapy in a coherent integrated manner.

Impact of ABC single nucleotide polymorphisms upon the efficacy and toxicity of induction chemotherapy in acute myeloid leukemia.

Anthracycline uptake could be affected by efflux pumps of the ABC family. The influence of 7 SNPs of ABC genes was evaluated in 225 adult de novo acute myeloid leukemia (AML) patients. After multivariate logistic regression there were no significant differences in complete remission, though induction death was associated to ABCB1 triple variant haplotype (p = .020). The ABCB1 triple variant haplotype was related to higher nephrotoxicity (p = .016), as well as this haplotype and the variant allele of ABCB1 rs1128503, rs2032582 to hepatotoxicity (p = .001; p = .049; p < .001). Furthermore, the variant allele of ABCC1 rs4148350 was related to severe hepatotoxicity (p = .044), and the variant allele of ABCG2 rs2231142 was associated to greater cardiac (p = .004) and lung toxicities (p = .038). Delayed time to neutropenia recovery was observed with ABCB1 rs2032582 variant (p = .047). This study shows the impact of ABC polymorphisms in AML chemotherapy safety. Further prospective studies with larger population are needed to validate these associations.

Pharmacogenomics and the treatment of acute myeloid leukemia.

Acute myeloid leukemia (AML) is a clinically and biologically heterogeneous malignancy that is primarily treated with combinations of cytarabine and anthracyclines. Although this scheme remains effective in most of the patients, variability of outcomes in patients has been partly related with their genetic variability. Several pharmacogenetic studies have analyzed the impact of polymorphisms in genes encoding transporters, metabolizers or molecular targets of chemotherapy agents. A systematic review on all eligible studies was carried out in order to estimate the effect of polymorphisms of anthracyclines and cytarabine pathways on efficacy and toxicity of AML treatment. Other emerging genes recently studied in AML, such as DNA repair genes, genes potentially related to chemotherapy response or AML prognosis, have also been included.

Association of SNPs with the efficacy and safety of immunosuppressant therapy after heart transplantation.

AIM: Studying the possible influence of SNPs on efficacy and safety of calcineurin inhibitors upon heart transplantation. MATERIALS & METHODS: In 60 heart transplant patients treated with tacrolimus or cyclosporine, we studied a panel of 36 SNPs correlated with a series of clinical parameters during the first post-transplantation year. RESULTS: The presence of serious infections was correlated to ABCB1 rs1128503 (p = 0.012), CC genotype reduced the probability of infections being also associated with lower blood cyclosporine concentrations. Lower renal function levels were found in patients with rs9282564 AG (p = 0.003), related to higher blood cyclosporine blood levels. A tendency toward increased graft rejection (p = 0.05) was correlated to rs2066844 CC in NOD2/CARD15, a gene related to lymphocyte activation. CONCLUSION: Pharmacogenetics can help identify patients at increased risk of clinical complications. Original submitted 30 January 2015; revision submitted 27 March 2015.

SNPs and taxane toxicity in breast cancer patients.

AIM: In order to identify genetic variants associated with taxanes toxicity, a panel with 47 SNPs in 20 genes involved in taxane pathways was designed. PATIENTS & METHODS: Genomic DNA of 113 breast cancer patients was analyzed (70 taking docetaxel, 43 taking paclitaxel). RESULTS: Two SNPs associated with docetaxel toxicity were identified: CYP3A4*1B with infusion-related reactions; and ERCC1 Gln504Lys with mucositis (p≤0.01). Regarding paclitaxel toxicity: CYP2C8 HapC and CYP2C8 rs1934951 were associated with anemia; and ERCC1 Gln504Lys with neuropathy (p≤0.01). CONCLUSION: Genes involved in DNA repair mechanisms and reactive oxygen species levels influence taxane toxicity in cancer patients treated with chemotherapy schemes not containing platinum. These findings could lead to better treatment selection for breast cancer patients.