The effect of vitamin D pathway genes and deferasirox pharmacogenetics on liver iron in thalassaemia major patients.

Monitoring and treating iron overload is crucial in transfusion-dependent thalassaemia patients. Liver stiffness measurement by transient elastography and T2* magnetic resonance imaging represent non-invasive ways to evaluate the adequacy of the iron chelation treatment. We explored the role of single nucleotide polymorphisms involved in vitamin D metabolism, transport and activity, and in deferasirox metabolism on liver iron burden parameters. One-hundred and five beta-thalassaemia patients, treated with deferasirox, have been enrolled. Drug plasma Ctrough and AUC were measured by a HPLC-UV method. Allelic discrimination was performed by real-time PCR. Age, UGT1A1-364 CT/TT and CYP27B1 -1260 GT/TT positively predicted liver stiffness values. Deferasirox dose and serum ferritin negatively predicted T2* data, whereas age and CYP2D6 1457 GG genotype positively influenced these values. The discoveries of this research may be useful for personalized medicine and the proposed method could be applied in patients with hereditary hemochromatosis and myelodysplastic syndromes.

Role of CYP1A1, ABCG2, CYP24A1 and VDR gene polymorphisms on the evaluation of cardiac iron overload in thalassaemia patients.

OBJECTIVES: Iron-burden-induced arrhythmia and heart failure are among the leading causes of morbidity and mortality in ß-thalassaemia major patients. T2* cardiac magnetic resonance remains the only reliable noninvasive method for the heart iron excess assessment. We explored the role of single nucleotide polymorphisms involved in vitamin D metabolism, transport and activity and in deferasirox (DFX) metabolism on cardiac iron burden. PATIENTS AND METHODS: One hundred and five ß-thalassaemia patients, treated with DFX, were enrolled in the present study. Drug plasma Ctrough was measured by a high-performance liquid chromatography-ultraviolet method. Allelic discrimination was carried out using the real-time PCR. RESULTS: CYP1A1*1189 CC, ABCG2 421 GA, CYP24A1 8620 GG and VDR TaqI CC single nucleotide polymorphisms influenced T2* values. Age, serum ferritin, ABCG2 421 GA, ABCG2 1194 +928 TC/CC, CYP24A1 22776 TT and VDR TaqI TC/CC were retained in linear regression model. CONCLUSION: Our results suggested, for the first time, the role of DFX and vitamin D pharmacogenetics on cardiac iron overload.

Circannual variation of mitotane and its metabolites plasma levels in patients with adrenocortical carcinoma.

OBJECTIVES: Mitotane is the reference drug for the adrenocortical carcinoma treatment; its pharmacological activity seems to depend on drug transformation in two active metabolites: o,p'-DDE (dichlorodiphenylethene) and o,p'-DDA (dichlorodiphenylacetate). Mitotane and metabolites are lipophilic agents; thus, they tend to accumulate into adipose tissues (white and brown), which change their prevalence seasonally. Aim of the work was to evaluate mitotane and metabolites plasma levels variation over the year, in adrenocortical cancer patients treated with Lysodren® for at least 6 months. METHODS: We enrolled a group of 86 adrenocortical carcinoma diagnosed patients, who underwent radical surgery and started mitotane as adjuvant treatment. For drug and metabolites plasma level (from samples collected ~12 h after the dose administration of mitotane, just before the subsequent administration) determination, a validated chromatographic method was used. KEY FINDINGS: Results showed an evidence of a seasonal trend for the three substance (o,p'-DDD, o,p'-DDE and o,p'-DDA) plasma levels, in terms of acrophases and lower values. Furthermore, it came out that male patients need a higher significant mitotane drug dose than female patients to reach mitotane therapeutic window. CONCLUSIONS: In conclusion, this is the first study assessing a mitotane plasma level variation over the year, but further studies in larger cohorts are required.

Bioequivalence of Branded and Generic Oxaliplatin: From Preclinical Assessment to Clinical Incidence of Hypersensitivity Reactions.

BACKGROUND: Generic anticancer drugs represent an opportunity in terms of cost savings but there are some concerns about their tolerability. The safety profiles of generic versus branded oxaliplatin formulations have never been studied in detail. PATIENTS AND METHODS: We tested in vitro concentrations, stability and efficacy of branded versus generic oxaliplatin formulations, then we retrospectively collected data about hypersensitivity reactions (HSR) of 427 colorectal cancer patients treated with oxaliplatin-based regimens. RESULTS: No significant difference in oxaliplatin concentration or time-dependent antiproliferative activity between branded and generic oxaliplatin was detected. The incidence of HSR was 12.1% (33/273 patients) in those treated with branded and 9.8% (15/154 patients) in those treated with generic oxaliplatin (p=0.46). The occurrence of grade III-IV HSRs and severe HSRs leading to oxaliplatin discontinuation were comparable. CONCLUSION: No difference between generic and branded formulations of oxaliplatin were demonstrated in preclinical nor in clinical settings. Generic oxaliplatin can be considered a safe alternative to branded formulation.

Plasma and intracellular imatinib concentrations in patients with chronic myeloid leukemia.

BACKGROUND: Imatinib (Gleevec, STI-571), a 2-phenylaminopyrimidine-type competitive inhibitor of Bcr-Abl kinase, is the current frontline therapy for patients with chronic myeloid leukemia, and it induces durable responses and prolonging event-free and progression-free survival. Monitoring imatinib trough plasma concentration is a simple and rapid way to determine if the drug exposure exceeds the clinical efficacy threshold (1 mcg/mL). Because the target enzyme is located within cells, adequate drug intracellular concentrations are needed to inhibit its function. METHODS: Chromatographic methods were used to quantify imatinib concentrations in both plasma and peripheral blood mononuclear cells collected from adult patients with chronic myeloid leukemia at the Department of Hematology. Samples were collected at steady state, and trough concentrations (24 ± 2 hours after last drug intake) were evaluated. Associations between variables were tested using the Pearson test; results are presented as mean (±SD). RESULTS: Thirty-five samples from 24 patients were collected; patients were mainly men (16, 66.7%), aged 60 years old (±13.1) and with a body mass index of 24.8 (±4.4). A positive and significant correlation (r = 0.203; P = 0.027) was found between imatinib plasma and intracellular concentrations. CONCLUSIONS: The observed correlation between plasma and intracellular imatinib concentrations suggests that they may be used to monitor drug exposure and treatment efficacy.

Influence of the CYP2B6 polymorphism on the pharmacokinetics of mitotane.

OBJECTIVE: The aim of this study was to assess the potential impact of the pharmacogenetic variability of CYP2B6 and ABCB1 genes on the pharmacokinetics of mitotane. METHODS: A retrospective analysis was carried out on 27 patients with adrenocortical carcinoma on postoperative adjunctive mitotane. CYP2B6 and ABCB1 polymorphisms were genotyped and tested for an association with plasma trough concentration after 3, 6, 9, and 12 months of therapy. RESULTS: Patients with the GT/TT genotype had higher mitotane plasma concentrations compared with patients with GG at 3 months (14.80 vs. 8.01 µg/ml; P=0.008) and 6 months (17.70 vs. 9.75 µg/ml; P=0.015). Multivariate logistic regression analysis showed that only the CYP2B6 rs3745274GT/TT genotype (odds ratio=10.7; P=0.017) was a predictor of mitotane plasma concentrations of at least 14 µg/ml after 3 months of treatment. Mitotane concentrations were not influenced by the polymorphisms of the ABCB1 gene. CONCLUSION: Evaluation of the CYP2B6 polymorphism enabled prediction of the individual response to adjuvant mitotane treatment.

A new HPLC-UV validated method for therapeutic drug monitoring of tyrosine kinase inhibitors in leukemic patients.

Development and validation of simple, rapid, and reliable high-performance liquid chromatography (HPLC)-UV method for quantification of major tyrosine kinase inhibitors, imatinib, dasatinib, and nilotinib, in human plasma is presented. Chromatographic separation of the drugs is achieved on an RP-C(18) column at flow rate of 0.9 mL/min at 35°C; eluate is monitored at 267 nm. Mean intra-day and inter-day precision for all compounds are 2.5 and 13.3%; mean accuracy is 13.9%; extraction recovery ranges within 40.24 and 81.81%. Calibration curves range from 10 to 0.005 µg/mL. Limits of detection are 10 ng/mL for imatinib and nilotinib, 50 ng/mL for dasatinib; limits of quantitation are 50 ng/mL for imatinib and nilotinib, 100 ng/mL for dasatinib. Although this method allows the detection of dasatinib, levels found in patients plasma are close to the limit of detection, then below the limit of quantitation. Quantification with HPLC-mass spectrometry, then, is required for dasatinib to give a correct evaluation. In conclusion, the sensitivity of this new method is sufficient to perform therapeutic monitoring and pharmacokinetic studies of imatinib and nilotinib but not dasatinib in CML patients.

New HPLC-MS method for the simultaneous quantification of the antileukemia drugs imatinib, dasatinib, and nilotinib in human plasma.

A new method using high performance liquid chromatography coupled with electrospray mass spectrometry is described for the quantification of plasma concentration of tyrosine kinase inhibitors imatinib, dasatinib and nilotinib. A simple protein precipitation extraction procedure was applied on 250 microl of plasma aliquots. Chromatographic separation of drugs and Internal Standard (quinoxaline) was achieved with a gradient (acetonitrile and water + formic acid 0.05%) on a C18 reverse phase analytical column with 20min of analytical run, at flow rate of 1 ml/min. Mean intra-day and inter-day precision for all compounds were 4.3 and 11.4%; mean accuracy was 1.5%; extraction recovery ranged within 95 and 114%. Calibration curves ranged from 10,000 to 62.5 ng/ml. The limit of quantification was set at 78.1 ng/ml for imatinib and at 62.5 ng/ml for dasatinib and nilotinib. This novel developed methodology allows a specific, sensitive and reliable simultaneous determination of the three tyrosine kinase inhibitors imatinib, dasatinib and nilotinib in a single chromatographic run, useful for drugs estimation in plasma of patients affected by chronic myeloid leukemia.

A new simple HPLC method for measuring mitotane and its two principal metabolites Tests in animals and mitotane-treated patients.

A new C18 reversed-phase column and UV HPLC method for the detection of mitotane, its principal metabolites, dichlorodiphenylacetate and dichlrodiphenylethene, and its precursor DDT is described. In this article mitotane, dichlorodiphenylacetate, and dichlrodiphenylethene concentrations in organs of rats fed on a mitotane diet, and the effects of erythromycin and grapefruit juice as cytochrome P450 common inhibitors are presented. Tissue accumulation of mitotane and dichlrodiphenylethene, the acquired ability to eliminate dichlorodiphenylacetate, and inhibition of beta-hydroxylation by both inhibitors are illustrated here. Blood samples from mitotane-treated patients revealed two correlations: plasma mitotane/dichlrodiphenylethene and plasma mitotane/red cell mitotane.

Salicylate inhibition of rat mammary carcinogenesis and angiogenesis in female rat compatible with misoprostol administration.

Epidemiological data suggest that non-steroidal anti-inflammatory drugs prevent colon cancer. The evidence for other types of tumour is less conclusive, though animal and in vitro studies indicate that they may be effective against mammary cancer cells. We assessed the effect of dietary acetylsalicylic and salicylic acid against dimethylbenzanthracene-induced rat tumours. Tumour angiogenesis was also investigated to explore the mechanism responsible for salicylate effect. Mammary tumours were induced in female Sprague-Dawley rats fed with different amounts of acetylsalicylic and salicylic acid. Serum vascular endothelial growth factor concentrations were measured and vascularization of basement membrane proteins injected in vivo (Matrigel) was determined by evaluation of haemoglobin content to assess the extent to which angiogenesis was inhibited. Dimethylbenzanthracene-induced carcinogenesis was inhibited by both acids and there was a log-dose/response correlation between the tumour diameter and salicylate concentration. Salicylic acid seems more effective than acetylsalicylic acid. Vascular endothelial growth factor was less concentrated in treated animals than in the controls and so was Matrigel haemoglobin. The mechanism involved, however, is still uncertain, though concomitant inhibition of tumour angiogenesis may be an important component. The documented salicylate serum VEGF modulation is interesting also for presence of the flk-1 receptor in mammary tumour cells of our model. Although misoprostol is a prostaglandin analogous its concomitant administration did not compromise the salicylate anti-tumour effect.