Cardiotoxicity of cyclophosphamide's metabolites: an in vitro metabolomics approach in AC16 human cardiomyocytes.

Cyclophosphamide is a widely used anticancer and immunosuppressive prodrug that unfortunately causes severe adverse effects, including cardiotoxicity. Although the exact cardiotoxic mechanisms are not completely understood, a link between cyclophosphamide's pharmacologically active metabolites, namely 4-hydroxycyclophosphamide and acrolein, and the toxicity observed after the administration of high doses of the prodrug is likely. Therefore, the objective of this study is to shed light on the cardiotoxic mechanisms of cyclophosphamide and its main biotransformation products, through classic and metabolomics studies. Human cardiac proliferative and differentiated AC16 cells were exposed to several concentrations of the three compounds, determining their basic cytotoxic profile and preparing the next study, using subtoxic and toxic concentrations for morphological and biochemical studies. Finally, metabolomics studies were applied to cardiac cells exposed to subtoxic concentrations of the aforementioned compounds to determine early markers of damage. The cytotoxicity, morphological and biochemical assays showed that 4-hydroxycyclophosphamide and acrolein induced marked cardiotoxicity at µM concentrations (lower than 5 µM), being significantly lower than the ones observed for cyclophosphamide (higher than 2500 µM). Acrolein led to increased levels of ATP and total glutathione on proliferative cells at 25 µM, while no meaningful changes were observed in differentiated cells. Higher levels of carbohydrates and decreased levels of fatty acids and monoacylglycerols indicated a metabolic cardiac shift after exposure to cyclophosphamide's metabolites, as well as a compromise of precursor amino acids used in the synthesis of glutathione, seen in proliferative cells' metabolome. Overall, differences in cytotoxic mechanisms were observed for the two different cellular states used and for the three molecules, which should be taken into consideration in the study of cyclophosphamide cardiotoxic mechanisms.

Intracellular activation of 4-hydroxycyclophosphamide into a DNA-alkylating agent in human leucocytes.

1.The conversion of the cyclophosphamide intermediate metabolite 4-hydroxycyclophosphamide (4-OHCP) to the final cytotoxic metabolite phosphoramide mustard (PAM) is classically assumed to occur via chemical hydrolysis of the phospho-ester bond. Whilst it has been suggested previously that this reaction could be enzyme-catalysed, there was only indirect evidence for this (i.e. formation of the by-product acrolein).2. Using an assay to detect formation of DNA-alkylating adducts which block PCR amplification (QPCR-block assay), we have demonstrated that 4-OHCP can be activated by peripheral blood mononuclear cells (PBMC). The DNA-alkylating potency of 4-OHCP in PBMC increased >18-fold compared to the intrinsic reactivity of 4-OHCP for purified gDNA.3. We also found that immortalised T-cells (Jurkat) had a similar ability to activate 4-OHCP into a DNA alkylating agent, whereas there was no appreciable activation in epithelial derived (Caco-2) cells. This suggests the possibility of tissue-specific enzyme expression.4. Of the candidate enzymes tested only recombinant human cAMP-phosphodiesterase-PDE4B and snake-venom phosphodiesterase (PDE-I) could catalyse this activation into a DNA-alkylating agent.5. This enzymatic catalysis of the phospho-ester bond (P-O-C) is a hitherto unrecognised feature of this important immunomodulatory drug and should be investigated further.

Interaction between PI3K/AKT and Hippo pathways during in vitro follicular activation and response to fragmentation and chemotherapy exposure using a mouse immature ovary model.

Understanding and control of the massive and accelerated follicular growth that occurs during in vitro culture of ovarian tissue is a crucial step toward the development of efficient culture systems that offer an attractive alternative to ovarian tissue transplantation for fertility restoration in cancer survivors. One outstanding question focuses on processes that occur prior to cryopreservation, such as tissue sectioning or chemotherapeutic treatment, might exacerbate this follicular activation. Although the PI3K/AKT/mTOR pathway is well known as a major trigger of physiological and chemotherapy-induced follicular activation, studies have shown that disruption of Hippo pathway due to ovarian fragmentation acts as an additional stimulator. This study aimed to characterize the possible interactions between these pathways using post-natal day 3 mouse ovaries cultured for 4 or 48 h. Morphology, gene transcription, and protein levels were assessed to investigate the impact of sectioning or chemotherapy exposure (4-hydroperoxycyclophosphamide [4HC], 3 and 20 µM). The effect of an mTORC1 inhibitor, Everolimus, alone or as a 4HC co-treatment to prevent follicle activation was evaluated. The results showed that organ removal from its physiological environment was as effective as sectioning for disruption of Hippo pathway and induction of follicle activation. Both PI3K/AKT/mTOR and Hippo pathways were involved in chemotherapy-induced follicular activation and responded to fragmentation. Surprisingly, Everolimus was able to prevent the activation of both pathways during chemotherapy exposure, suggesting cross-talk between them. This study underscores the major involvement of PI3K/AKT/mTOR and Hippo pathways in in vitro follicle activation and provides evidence that both can be regulated using mTORC1 inhibitor.

Causes and possibilities to circumvent cyclophosphamide toxicity.

Cyclophosphamide is an inert prodrug converted into 4-hydroxycyclophosphamide (OHCP) by hepatic hydroxylation. OHCP is in equilibrium with its tautomeric aldophosphamide (ALDO). From ALDO, the cytotoxic active metabolites are formed enzymatically by phosphodiesterases; these are the alkylating metabolite phosphoramide mustard (PAM) and the proapoptotic aldehyde 3-hydroxypropanal (HPA). PAM damages the DNA by alkylation; HPA amplifies the thereby induced apoptosis. The generally accepted view that acrolein, which is believed to be formed in the formation of PAM by ß-elimination from ALDO would be mainly responsible for the toxicity of cyclophosphamide, has to be revised because no acrolein is formed in the systemic circulation of patients after cyclophosphamide administration. It is shown that not acrolein, but OHCP itself is the true toxic metabolite of cyclophosphamide. Toxicity tests with OHCP and PAM were carried out, which demonstrated that OHCP unfolds its toxicity, not as a carrier of PAM but is toxic itself by reacting with nucleophilic groups of macromolecules, for example, thiol groups of membrane proteins. Further experiments demonstrate that the toxicity of oxazaphosphorine cytostatics may be drastically reduced if the formation of the pharmacologically active metabolite ALDO bypasses the formation of OHCP. Toxicity experiments in mice with S-ethanol-cyclophosphamide (SECP) that hydrolyzes to OHCP show that SECP is as toxic as OHCP, whereas the thiazolidine of ALDO, which hydrolyzes to ALDO bypassing OHCP is 7-9 times less toxic without loss of antitumor activity.

Bi-allelic recessive loss-of-function mutations in FIGLA cause premature ovarian insufficiency with short stature.

Premature ovarian insufficiency (POI) is a group of heterogeneous disorders characterized by decreased ovarian reserve and increased follicle stimulating hormone (FSH) levels. It is rarely associated with short stature. FIGLA mutations with POI are identified with regard to heterozygosity; till date, only one affected family has been identified with homozygous mutations in FIGLA but without functional evaluation. Here, we described two POI patients from a consanguineous family from China. An 18-year-old girl and her sister presented with primary amenorrhea and increased FSH and luteinizing hormone levels, but the sister also presented with short stature and bone age delay. Whole-genome sequencing analysis identified a recurrent homozygous mutation in the FIGLA gene, c.2 T > C (p.Met1Thr), in this family member with POI; this variant was segregated within the pedigree. This change was absent in 382 control subjects, and we did not detect any mutations in 39 other idiopathic POI patients. in vitro functional analysis indicates that the p.Met1Thr mutation does not affect the transcription of the FIGLA gene, but blocks the synthesis of the full-length FIGLA protein. Our results support the notion that bi-allelic recessive loss-of-function effects of FIGLA contribute to POI patients with short stature and expand the FIGLA-related phenotypic spectrum.

Low-dose trofosfamide plus rituximab is an effective and safe treatment for diffuse large B-cell lymphoma of the elderly: a single center experience.

BACKGROUND: Rituximab plus combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is broadly accepted as standard for the treatment of diffuse large B-cell lymphoma (DLBCL). Nevertheless, there is sparsely data concerning the management of elderly patients. METHODS: We performed a retrospective study of treatment with rituximab and low-dose trofosfamide in elderly patients (≥ 75 years) with DLBCL who were not suitable for R-CHOP or R-CHOP-like regimens or who did not consent to aggressive treatment. The choice regarding the qualification for R-CHOP or R-CHOP-like regimen was left to the estimation of the treating physicians. RESULTS: Eleven patients with a median age of 83 years (range, 75-90 years) were included. The age-adjusted international prognostic index was low risk in one patient, low-intermediate in four patients, high-intermediate in three patients, and high risk in 3 patients. All patients were evaluable for response. Five patients (45%) achieved a complete response, three (27%) a partial response, one (9%) stable disease, and two (18%) progressive disease. The estimated 1-yr overall survival was 54.5%, and the estimated 1-yr progression-free survival 45.5%, however, three patients (27%) were alive without evidence of disease at 16-20 months from start of treatment. Main toxicity was leukopenia (36% grade III or IV), whereas grade III/IV non-hematological adverse events did not occur. CONCLUSIONS: Due to its potency and low toxicity, trofosfamide/rituximab might represent an alternative therapy for DLBCL of elderly patients not suitable for R-CHOP. This observation, however, should be confirmed in a larger patient population within a prospective clinical trial.

Short-term exposure of human ovarian follicles to cyclophosphamide metabolites seems to promote follicular activation in vitro.

How chemotherapy affects dormant ovarian primordial follicles is unclear. The 'burnout' theory, studied only in mice, suggests cyclophosphamide enhances primordial follicle activation. Using 4-hydroperoxycyclophosphamide (4hc) and phosphoramide mustard (PM), this study assessed how the active cyclophosphamide metabolites 4-hydroxycyclophosphamide (4-OHC) and PM, affect human primordial follicles. Frozen-thawed human ovarian samples were sliced and cultured with basic culture medium (cultured controls) or with 4hc/PM (3 µmol/l/10 µmol/l) (treated samples) for 24-48 h. Follicular counts and classification, Ki67 and anti-Müllerian hormone (AMH) immunohistochemistry and an apoptosis assay were used for evaluation, and 17ß-oestradiol and AMH were measured in spent media samples. Generally, there was primordial follicle decrease and elevated developing follicle rates in treated samples compared with cultured (P = 0.04 to P < 0.0005) and uncultured controls (P < 0.05 to P < 0.0001). No traces of apoptosis were found. There were almost twicethe levels of AMH and 17ß-oestradiol in treated compared with untreated samples (AMH with 4hc 3 µmol/l; P = 0.04). All follicles stained positively for AMHincluded treated samples. Ki67 positive staining was noted in all samples. Cyclophosphamide metabolites seem to enhance human primordial follicle activation to developing follicles, in vitro. Study findings support the 'burnout' theory as the mechanism of chemotherapy-induced ovarian toxicity.

Genetic markers in CYP2C19 and CYP2B6 for prediction of cyclophosphamide's 4-hydroxylation, efficacy and side effects in Chinese patients with systemic lupus erythematosus.

AIMS: The aim of the study was to investigate the combined impact of genetic polymorphisms in key pharmacokinetic genes on plasma concentrations and clinical outcomes of cyclophosphamide (CPA) in Chinese patients with systemic lupus erythematosus (SLE). METHODS: One hundred and eighty nine Chinese SLE patients treated with CPA induction therapy (200 mg, every other day) were recruited and adverse reactions were recorded. After 4 weeks induction therapy, 128 lupus nephritis (LN) patients continued to CPA maintenance therapy (200-600 mg week(-1)) for 6 months, and their clinical outcomes were recorded. Blood samples were collected for CYP2C19, CYP2B6, GST and PXR polymorphism analysis, as well as CPA and its active metabolite (4-hydroxycyclophosphamide (4-OH-CPA)) plasma concentration determination. RESULTS: Multiple linear regression analysis revealed that CYP2B6 -750 T > C (P < 0.001), -2320 T > C (P < 0.001), 15582C > T (P = 0.017), CYP2C19*2 (P < 0.001) and PXR 66034 T > C (P = 0.028) accounted for 47% of the variation in 4-OH-CPA plasma concentration. Among these variants, CYP2B6 -750 T > C and CYP2C19*2 were selected as the combination genetic marker because these two SNPs contributed the most to the inter-individual variability in 4-OH-CPA concentration, accounting for 23.6% and 21.5% of the variation, respectively. Extensive metabolizers (EMs) (CYP2B6 -750TT, CYP2C19*1*1) had significantly higher median 4-OH-CPA plasma concentrations (34.8, 11.0 and 6.6 ng ml(-1) for EMs, intermediate metabolizers (IMs) and poor metabolizers (PMs), P < 0.0001), higher risks of leukocytopenia (OR = 7.538, 95% CI 2.951, 19.256, P < 0.0001) and gastrointestinal toxicity (OR = 7.579, 95% CI 2.934, 19.578, P < 0.0001), as well as shorter median time to achieve complete remission (13.2, 18.3 and 23.3 weeks for EMs, IMs and PMs, respectively, P = 0.026) in LN patients than PMs (CYP2B6 -750CC, CYP2C19*2*2) and IMs. CONCLUSIONS: Our findings have indicated that genetic markers of drug metabolizing enzymes could predict the 4-hydroxylation, adverse reactions and clinical efficacy of CPA. This is a necessary first step towards building clinical tools that will help assess clinical benefit and risk before undergoing CPA treatment in Chinese SLE patients.

Cyclophosphamide-induced vasopressin-independent activation of aquaporin-2 in the rat kidney.

Because cyclophosphamide-induced hyponatremia was reported to occur without changes in plasma vasopressin in a patient with central diabetes insipidus, we hypothesized that cyclophosphamide or its active metabolite, 4-hydroperoxycyclophosphamide (4-HC), may directly dysregulate the expression of water channels or sodium transporters in the kidney. To investigate whether intrarenal mechanisms for urinary concentration are activated in vivo and in vitro by treatment with cyclophosphamide and 4-HC, respectively, we used water-loaded male Sprague-Dawley rats, primary cultured inner medullary collecting duct (IMCD) cells, and IMCD suspensions prepared from male Sprague-Dawley rats. In cyclophosphamide-treated rats, significant increases in renal expression of aquaporin-2 (AQP2) and Na-K-2Cl cotransporter type 2 (NKCC2) were shown by immunoblot analysis and immunohistochemistry. Apical translocation of AQP2 was also demonstrated by quantitative immunocytochemistry. In both rat kidney and primary cultured IMCD cells, significant increases in AQP2 and vasopressin receptor type 2 (V2R) mRNA expression were demonstrated by real-time quantitative PCR analysis. Confocal laser-scanning microscopy revealed that apical translocation of AQP2 was remarkably increased when primary cultured IMCD cells were treated with 4-HC in the absence of vasopressin stimulation. Moreover, AQP2 upregulation and cAMP accumulation in response to 4-HC were significantly reduced by tolvaptan cotreatment in primary cultured IMCD cells and IMCD suspensions, respectively. We demonstrated that, in the rat kidney, cyclophosphamide may activate V2R and induce upregulation of AQP2 in the absence of vasopressin stimulation, suggesting the possibility of drug-induced nephrogenic syndrome of inappropriate antidiuresis (NSIAD).

The GSTA1 polymorphism and cyclophosphamide therapy outcomes in lupus nephritis patients.

Pulsed low-dose cyclophosphamide (CTX) therapy has become a very effective approach in improving the clinical outcomes of lupus nephritis (LN) patients. However, variations of CTX therapeutic outcomes in LN patients are incompletely understood. We investigated the contributions of known allelic variants to CTX therapy outcomes in 77 LN patients. Then, 22 out of the 77 patients were randomly enrolled to evaluate the pharmacokinetic profiles. LN patients with a GSTA1*A mutation (CT heterozygous) had more risk of non-remission (44% vs. 20%, P=0.005). Pharmacokinetic data indicated that patients with a GSTA1*A heterozygous variant had a lower exposure to 4-hydroxycyclophosphamide (4OHCTX) compared to wild-type patients (AUC4OHCTX: 12.8 (9.8, 19.5) vs. 27.5 (18.1, 32.8) h mg/l, P=0.023). Clinical remission was significantly related to higher exposure of 4OHCTX (P=0.038). In conclusion, LN patients with GSTA1*A heterozygous genotypes had poor CTX treatment remission due to less exposure to activated metabolites of CTX.

α-Melanocyte-stimulating hormone: a protective peptide against chemotherapy-induced hair follicle damage?

BACKGROUND: Effective, safe and well-tolerated therapeutic and/or preventive regimens for chemotherapy-induced alopecia (CIA) still remain to be developed. Because α-melanocyte-stimulating hormone (α-MSH) exerts a number of cytoprotective effects and is well tolerated, we hypothesized that it may be a candidate CIA-protective agent. OBJECTIVES: To explore, using a human in vitro model for chemotherapy-induced hair follicle (HF) dystrophy that employs the key cyclophosphamide metabolite (4-hydroperoxy-cyclophosphamide, 4-HC), whether α-MSH protects from 4-HC-induced HF dystrophy. METHODS: Microdissected human scalp HFs from four individuals were treated with 4-HC, α-MSH and 4-HC plus α-MSH. Changes in HF cycling, melanin distribution and hair matrix keratinocyte proliferation/apoptosis were examined by quantitative (immune-) morphometry. Expression of the cytoprotective enzyme haem oxygenase-1 (HO-1) was determined by real-time reverse transcriptase-polymerase chain reaction in HF of two individuals. RESULTS: In 50% of the individuals α-MSH reduced melanin clumping as an early sign of 4-HC-induced disruption of follicular pigmentation. α-MSH reduced 4-HC-induced apoptosis in the HFs of one female patient. These protective effects of α-MSH were not associated with changes in 4-HC-induced catagen induction. α-MSH and 4-HC both increased HO-1 mRNA expression, while the combination of both agents had additive effects on HO-1 transcription. CONCLUSIONS: Exogenous α-MSH exerts moderate HF-protective effects against 4-HC-induced human scalp HF damage and upregulates the intrafollicular expression of a key cytoprotective enzyme. However, as substantial interindividual response variations were found, further studies are needed to probe α-MSH as a candidate CIA-protective agent.

Schedule-dependent cytotoxicity of Etoposide and cyclophosphamide in P-glycoprotein-expressing human leukemic K-562 cells.

Combination chemotherapy is often used to treat cancer. Many studies have shown schedule-dependent effects between anticancer drugs. Our previous studies showed that K-562 cells pretreated with non-cytotoxic concentrations of 4-hydroperoxycyclophosphamide (4-HPC), which is a preactivated analog of cyclophosphamide (CY), enhanced the cytotoxicity of etoposide (VP-16). The appearance of cellular resistance to anticancer drugs is a major problem in cancer chemotherapy. P-Glycoprotein (P-gp) plays an important role in drug resistance, and VP-16 is a substrate for this efflux pump. In the present study, we demonstrated schedule-dependent cytotoxicity of VP-16 and CY in P-gp-overexpressed K-562/P-gp cells. Cytotoxicity of VP-16 was enhanced in K-562/P-gp cells that were pretreated with a non-cytotoxic concentration of 4-HPC compared to that of cells not treated with 4-HPC. 4-HPC arrested the cell cycle at S phase. Cells in S phase are most sensitive to VP-16. The results suggest that cell cycle arrest by 4-HPC pretreatment may be responsible for the enhanced cytotoxicity of VP-16. The findings in this study should lead to improvements in clinical combination chemotherapy.

Fast quantification of cyclophosfamide and its N-dechloroethylated metabolite 2-dechloroethylcyclophosphamide in human plasma by UHPLC-MS/MS.

A rapid, novel and reliable UHPLC-MS/MS method was developed and validated for simultaneous determination of cyclophosphamide (CP) and its dechloroethylated metabolite, 2-dechloroethylcyclosphamide (2-DCECP) in human plasma. The plasma samples were conducted by protein precipitation with 3-fold acetonitrile, containing 0.1% formic acid. Mass spectrometric detection was performed using electrospray positive ionization with multiple reaction monitoring mode, using tinidazole as internal standard (IS). Chromatographic separation was performed on an Agilent poroshell 120 SB-C18 column (2.1 × 75 mm, 2.7 µm) using gradient elution of acetonitrile and 0.1% formic acid at a flow rate of 0.5 mL/min, the total run time was 2.5 min. The limit of quantification (LOQ) was 20 ng/mL for both CP and 2-DCECP. Accuracies and precisions were <15% at LOQ and below 10% at quality control concentration levels. This UHPLC-MS/MS method was successfully applied for the estimation of CP and 2-DCECP in human plasma, which was also useful for clinical toxicology studies and therapeutic drug monitoring of CP.

Labeled oxazaphosphorines for applications in mass spectrometry studies. 2. Synthesis of deuterium-labeled 2-dechloroethylcyclophosphamides and 2- and 3-dechloroethylifosfamides.

The prodrugs cyclophosphamide (CP) and ifosfamide (IF) each metabolize to an active alkylating agent through a cytochrome P450-mediated oxidation at the C-4 position. Competing with this activation pathway are enzymatic oxidations at the exocyclic α and α' carbons, which result in dechloroethylation of CP and IF. The incidence of oxidation at one position relative to another is believed to be at least one factor underlying the high degree of interpatient variability in both CP and IF pharmacokinetics. As standards for the mass spectrometry quantification of dechloroethylation, the following were synthesized: (1) [4,4,5,5-(2) H4 ]-2-dechloroethylcyclophosphamide (equivalent to [4,4,5,5-(2) H4 ]-3-dechloroethylifosfamide); (2) [α,α,4,4,5,5-(2) H6 ]-2-dechloroethylcyclophosphamide (equivalent to [α,α,4,4,5,5-(2) H6 ]-3-dechloroethylifosfamide); and (3) [α,α,4,4,5,5-(2) H6 ]-2-dechloroethylifosfamide. The common precursor to all of the target compounds was [2,2,3,3-(2) H4 ]-3-aminopropanol. A one-pot reaction of this compound with POCl3 and unlabeled or labeled 2-chloroethylamine hydrochloride gave the d4 and d6 labeled 2-dechloroethylcyclophosphamides. The construction of the 2-dechloroethylifosfamide from the aminopropanol required five discreet steps. Optimization of the synthetic pathways and stability studies are discussed.

[Anti-tumor effects of a novel cyclophosphamide derivate 9b in vivo and in vitro].

This study is to investigate the anti-tumor activities of a novel cyclophosphamide derivate 4, 6-diphenyl cyclophosphamide (9b) in vivo and in vitro, and its possible mechanism of action. The inhibitory effects of 9b on human hepatoma cell line HepG2, human breast carcinoma cell line MCF-7 and human myeloid leukemia cell line K562 were measured by MTT assay in vitro. Cell cycle distribution and apoptotic rate were evaluated by flow cytometry. To evaluate the anti-tumor effect of 9b in vivo, mouse model bearing inoculated H22 tumor was established. The results indicated that 9b could inhibit the proliferation of HepG2, MCF-7 and K562 cells in a dose and time dependent manner. The ICo50 values of 9b were 32.34 micromol.L-1 to HepG2 cells, 87.07 micromol.L-1 to MCF-7 cells and 149.10 micromol.L-1 to K562 cells after incubation for 48 h. The results of flow cytometry indicated that after being treated for 48 h with different concentrations of 9b, the ratios of HepG2, MCF-7 cells at the Go/G1 phase and K562 cells at the G0/Gl phase and G2/M phase increased significantly compared with control group, and the apoptotic rate increased with the increase of the concentration of 9b. 9b could significantly reduce tumor weight of H22 solid tumor mouse model in vivo. To summarize, 9b showed significantly anti-tumor activity in vivo and in vitro, of which the mechanism might be associated with the change of cell cycle distribution and induction of tumor cell apoptosis.

Pharmacogenomic associations of cyclophosphamide pharmacokinetic candidate genes with 4hydroxycyclophosphamide formation in children with Cancer.

PURPOSE: 4-hydroxycyclophosphamide (4HCY) is the principal precursor to the cytotoxic metabolite of cyclophosphamide (CY), which is often used as first-line treatment of children with cancer. There is conflicting data regarding the relationship between CY efficacy, toxicity, and pharmacokinetics with the genes encoding proteins involved in 4HCY pharmacokinetics, specifically its formation and elimination. METHODS: We evaluated germline pharmacogenetics in children with various malignancies receiving their first CY dose. Using linear regression, we analyzed the associations between two pharmacokinetic outcomes - how fast a child cleared CY (i.e., CY clearance) and the ratio of the 4HCY/CY exposure, specifically area under the plasma concentration-time curve (AUC), and 372 single nucleotide polymorphisms (SNP) in 14 drug-metabolizing transporters or enzymes involved in 4HCY formation or elimination. RESULTS: Age was associated with the ratio of 4HCY/CY AUC (P = 0.004); Chemotherapy regimen was associated with CY clearance (P = 0.003). No SNPs were associated with CY clearance or the ratio of 4HCY/CY AUC after controlling for a false discovery rate. CONCLUSION: Age and chemotherapy regimen, but not germline pharmacogenomics, were associated with CY clearance or the ratio of 4HCY/CY AUC. Other methods, such as metabolomics or lipidomics, should be explored.

In vitro chemosensitivity testing of the feline large granular lymphocyte cell line (S87).

BACKGROUND: Feline large granular lymphocyte (LGL) lymphoma is an aggressive neoplasia characterised by short survival and poor response to chemotherapy. OBJECTIVES: In this study, the effect of different chemotherapeutic agents on the growth kinetics of the feline cell line S87, a non-MHC-restricted feline LGL cell line, was investigated. Where possible, IC50 (inhibitory concentration 50) values were determined. The IC50 values of the cell line as lymphoma models can provide clues to the situation in vivo and serve as a basis for studying resistance mechanisms. METHODS: Cells were incubated with various concentrations of vincristine, doxorubicin, 4-hydroperoxycyclophosphamide, prednisolone, methotrexate and L-asparaginase for 24 and 48 h, respectively. RESULTS: The IC50 values could be determined as 14.57 (7.49-28.32) µg/mL at 24 h incubation and 5.72 (4.05-8.07) µg/mL at 48 h incubation for doxorubicin and 9.12 (7.72-10.76) µg/mL at 24 h incubation and 4.53 (3.74-5.47) µg/mL at 48 h incubation for 4-hydroperpoxycyclophosphamide. Treatment with vincristine and methotrexate resulted in relatively high cell resistance whereas L-asparaginase and prednisolone treatment led to a reduction in cell number compared to control while cell viability was not affected (cytostatic effect). CONCLUSION: Overall, the feline LGL cell line S87 proves to be relatively sensitive to doxorubicin and 4-hydroperoxycyclophosphamide and relatively resistant to treatment with vincristine, prednisolone, methotrexate and L-asparaginase. The results of this study can be used for further investigations on resistance mechanisms in feline LGL lymphoma. Doxorubicin and cyclophosphamide can be interpreted as promising candidates for the therapy of feline LGL lymphomas.

Population pharmacokinetics analysis of cyclophosphamide with genetic effects in patients undergoing hematopoietic stem cell transplantation.

PURPOSE: To build a population pharmacokinetic (PK) model of cyclophosphamide (CY) and its metabolite, 4-hydroxycyclophosphamide (HCY), in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) and to identify covariates, including genetic polymorphisms, which affect CY and HCY PK parameters. METHOD: The study cohort comprised 21 patients undergoing HSCT who received CY intravenously between 2009 and 2011. Clinical characteristics and CY and HCY concentration data were collected for all patients, and ABCB1, ABCC2, GSTA1, GSTM1, GSTP1, GSTT1, CYP2B6, CYP2C19, and CYP3A5 genotyping was performed. A hypothetical enzyme compartment was conducted using the NONMEM program. RESULTS: A population PK analysis showed that the ABCC2 1249 genotype and aspartate aminotransferase levels significantly affected non-induced clearance (CL UI) and induced clearance (CL I) of CY, respectively. The final estimate of the mean CL UI and CL I of CY was 15.5 and 0.683 L/h, respectively, and the mean volume of distribution (V 1) of CY was 88.0 L. The inter-individual variability for CL UI, CL I, and V 1 of CY was 52.8, 200, and 18.0 %, respectively. Additionally, the CL UI of CY was significantly decreased to approximately 51 % in patients with the 1249 GA heterozygous genotype compared to those with the 1249 GG wild-type genotype (p < 0.05). There were only three heterozygous GA variants of ABCC2 1249 in the study patients. CONCLUSIONS: The population PK model developed in this study implies an influence of genetic factors on the clearance of CY. Clearance was moderately reduced in patients with the ABCC2 1249GA heterozygous genotype.

Old wine in new pipes? Treatment of advanced non-small cell lung cancer with trofosfamide.

BACKGROUND: The aim of this retrospective study was to examine the effect of oral trofosfamide in patients with advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients with histologically or cytologically proven NSCLC, who had received at least 2 other therapies, were enrolled. The primary clinical end point was progression-free survival (PFS); secondary end points included overall survival (OS), response rate and toxicity. RESULTS: 23 patients were enrolled, 1 of whom was excluded due to non-compliance. The patients had received a median of 3 prior therapies (range 2-4). Regarding all 22 patients, median PFS was 14 weeks (95% confidence interval (CI) 9.96-18.04). The median OS was 32 weeks (95% CI 17.12-46.88). The median duration of trofosfamide therapy was 10.5 weeks (interquartile range 6.5-17.3). 20 patients (90.9%) had stable disease; 2 were not assessable. Trofosfamide therapy was stopped in 4 patients (18.2%) due to side effects. CONCLUSION: Trofosfamide is an orally applicable, well-tolerated and cost-effective drug that works in patients with advanced NSCLC, who have undergone at least 2 lines of therapy. Trofosfamide seems to be a therapeutic option in NSCLC as a further therapy line. These preliminary data need to be confirmed in a larger trial.

[Classical oxazaphosphorines--metabolism and therapeutic properties--new implications]. / Klasyczne oksazafosforinany--metabolizm i wlasciwosci terapeutyczne--nowe implikacje.

Cyclophosphamide (CPA) and ifosfamide (IFO) belong to oxazaphosphorine drugs and for a few decades have been widely used for treatment of solid tumours and haematological malignancies. Both drugs are administered in pharmacologically inactive form and require metabolic activation by cytochrome P-450 (CYP). Metabolic transformations taking place under the action of specific CYP isoenzymes lead to the formation of therapeutically essential metabolites and some toxic compounds affecting quality of therapy. The first stage of these conversions is connected with hydroxylation reactions occurring on the C-4 carbon atom within a ring and C-1 atoms of 2-chloroethyl chains. As a result of C-4 hydroxylation 4-hydroxy derivatives (4-OH-CPA and 4-OH-IFO) are formed and remain in tautomeric equilibrium with aldo compounds which in cancer cells spontaneously release cytotoxic phosphoramide mustards and urotoxic acrolein. At the same time hydroxychloroethyl compounds formed during hydroxylation of side-chains are unstable and collapse with the release of inter alia nephro- and neurotoxic chloroacetaldehyde (CAA). Due to formation of toxic metabolites it is essential to use some preventive agents such as mesna and recently examined agmatine. Since CPA and IFO are widely used anticancer drugs, their efficacy is limited not only by their toxicity but also due to occurring resistance. This resistance seems to be a result of changes of expression and activity of enzymes such as CYP and aldehyde dehydrogenase (ALDH) and increase of intracellular levels of glutathione (GSH) and glutathione S-transferase (GST). At present a few methods of overcoming this resistance are being examined including the use of metabolism modulators, antisense oligonucleotides selectively inhibiting gene expression, and introducing genes of some CYP isoenzymes to a cancer tissue.