Exposure to the antineoplastic ifosfamide alters molecular pathways related to cardiovascular function, increases heart rate, and induces hyperactivity in zebrafish (Danio rerio).

Ifosfamide is an alkylating antineoplastic drug used in chemotherapy, but it is also detected in wastewater. Here, the objectives were to (1) determine teratogenic, cardiotoxic, and mitochondrial toxicity potential of ifosfamide exposure; (2) elucidate mechanisms of toxicity; (3) characterize exposure effects on larval behavior. Survival rate, hatch rate, and morphological deformity incidence were not different amongst treatments following exposure levels up to 1000 µg/L ifosfamide over 7 days. RNA-seq reveled 231 and 93 differentially expressed transcripts in larvae exposed to 1 µg/L and 100 µg/L ifosfamide, respectively. Several gene networks related to vascular resistance, cardiovascular response, and heart rate were affected, consistent with tachycardia observed in exposed embryonic fish. Hyperactivity in larval zebrafish was observed with ifosfamide exposure, potentially associated with dopamine-related gene networks. This study improves ecological risk assessment of antineoplastics by elucidating molecular mechanisms related to ifosfamide toxicity, and to alkylating agents in general.

Ifosfamide - History, efficacy, toxicity and encephalopathy.

In this review we trace the passage of fundamental ideas through 20th century cancer research that began with observations on mustard gas toxicity in World War I. The transmutation of these ideas across scientific and national boundaries, was channeled from chemical carcinogenesis labs in London via Yale and Chicago, then ultimately to the pharmaceutical industry in Bielefeld, Germany. These first efforts to checkmate cancer with chemicals led eventually to the creation of one of the most successful groups of cancer chemotherapeutic drugs, the oxazaphosphorines, first cyclophosphamide (CP) in 1958 and soon thereafter its isomer ifosfamide (IFO). The giant contributions of Professor Sir Alexander Haddow, Dr. Alfred Z. Gilman & Dr. Louis S. Goodman, Dr. George Gomori and Dr. Norbert Brock step by step led to this breakthrough in cancer chemotherapy. A developing understanding of the metabolic disposition of ifosfamide directed efforts to ameliorate its side-effects, in particular, ifosfamide-induced encephalopathy (IIE). This has resulted in several candidates for the encephalopathic metabolite, including 2-chloroacetaldehyde, 2-chloroacetic acid, acrolein, 3-hydroxypropionic acid and S-carboxymethyl-L-cysteine. The pros and cons for each of these, together with other IFO metabolites, are discussed in detail. It is concluded that IFO produces encephalopathy in susceptible patients, but CP does not, by a "perfect storm," involving all of these five metabolites. Methylene blue (MB) administration appears to be generally effective in the prevention and treatment of IIE, in all probability by the inhibition of monoamine oxidase in brain potentiating serotonin levels that modulate the effects of IFO on GABAergic and glutamatergic systems. This review represents the authors' analysis of a large body of published research.

Microphysiological Drug-Testing Platform for Identifying Responses to Prodrug Treatment in Primary Leukemia.

Despite increasing survival rates of pediatric leukemia patients over the past decades, the outcome of some leukemia subtypes has remained dismal. Drug sensitivity and resistance testing on patient-derived leukemia samples provide important information to tailor treatments for high-risk patients. However, currently used well-based drug screening platforms have limitations in predicting the effects of prodrugs, a class of therapeutics that require metabolic activation to become effective. To address this issue, a microphysiological drug-testing platform is developed that enables co-culturing of patient-derived leukemia cells, human bone marrow mesenchymal stromal cells, and human liver microtissues within the same microfluidic platform. This platform also enables to control the physical interaction between the diverse cell types. Herein, it is made possible to recapitulate hepatic prodrug activation of ifosfamide in their platform, which is very difficult in traditional well-based assays. By testing the susceptibility of primary patient-derived leukemia samples to the prodrug ifosfamide, sample-specific sensitivities to ifosfamide in primary leukemia samples are identified. The microfluidic platform is found to enable the recapitulation of physiologically relevant conditions and the testing of prodrugs including short-lived and unstable metabolites. The platform holds great potential for clinical translation and precision chemotherapy selection.

Genome-wide gene expression analysis reveals molecular insights into the drug-induced toxicity of nephrotoxic agents.

Drug-induced nephrotoxicity is frequently reported. However, the mechanisms underlying nephrotoxic medications and their overlapping molecular events, which might have therapeutic value, are unclear. We performed a genome-wide analysis of gene expression and a gene set enrichment analysis to identify common and unique pathways associated with the toxicity of colistin, ifosfamide, indomethacin, and puromycin. Rats were randomly allocated into the treatment or control group. The treatment group received a toxic dose once daily of each investigated drug for 1 week. Differentially expressed genes were found in the drug-treated kidney and liver compared to the control, except for colistin in the liver. Upregulated pathways were mainly related to cell death, cell cycle, protein synthesis, and immune response modulation in the kidney. Cell cycle was upregulated by all drugs. Downregulated pathways were associated with carbon metabolism, amino acid metabolism, and fatty acid metabolism. Indomethacin, colistin, and puromycin shared the most altered pathways in the kidney. Ifosfamide and indomethacin affected molecular processes greatly in the liver. Our findings provide insight into the mechanisms underlying the renal and hepatic adverse effects of the four drugs. Further investigation should explore the combinatory drug therapies that attenuate the toxic effects and maximize the effectiveness of nephrotoxic drugs.

Ifosfamide-induced acute kidney injury in a patient with leiomyosarcoma: A case report.

BACKGROUND: Leiomyosarcoma (LMS) is an aggressive soft tissue sarcoma that is derived from smooth muscles. Ifosfamide is in use for advanced metastatic LMS. CASE: A-44-years old woman with a chief complaint of pain in the epigastric area, itching, coughing, nausea, and vomiting was referred to the emergency department. Her medical history was LMS. She had taken Ifosfamide and mesna in her last chemotherapy. Seventy percent of her liver and her left kidney were removed 4 years ago to prevent the progress of the disease. Because of the increase in the level of creatinine and urea in the initial laboratory report, a Shaldon catheter was inserted for the patient, and she was under emergency dialysis for 3 h. In addition, during the six-day hospitalization period, dialysis was done two times. Finally, the patient was discharged with improved clinical tests accompanied by a twice-weekly dialysis order. CONCLUSION: Ifosfamide is metabolized into chloroacetaldehyde, which can cause acute kidney injury. Recovery from acute kidney injury may not always be perfect and can lead to some degree of chronic kidney disease. Opposite to hemorrhagic cystitis, mesna is not effective in preventing ifosfamide's nephrotoxicity and N-acetylcysteine may be effective in the prevention of this nephrotoxicity.

The protective effect of Morin against ifosfamide-induced acute liver injury in rats associated with the inhibition of DNA damage and apoptosis.

Morin is a flavonoid and broadly found in white berry and cranberry branch. Ifosfamide (IFOS) is known as an anticancer and cytotoxic drug especially on the liver. This study aimed to explore the potential protective effects of Morin against IFOS-induced liver toxicity in rats. The model group of rats received a single injection of IFOS (500 mg/kg; i.p.) at day 2, whereas the protective groups of rats were given two different doses of Morin (100 and 200 mg/kg; given by gavage) at days 1 and 2. All animals were then culled 24 h post-IFOS injection. We observed that IFOS caused liver injury, oxidative stress, inflammation, DNA damage, and apoptosis. However, Morin decreased the levels of aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT) (p < 0.05). While Morin contributed to the recovery of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) levels, Morin decreased the levels of malondialdehyde (MDA) induced by IFOS in the liver (p < 0.05). Besides, the levels of nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and P53 measured by ELISA test were reduced via Morin administration (p < 0.05). Lastly, the mRNA transcript levels of Bax, Apaf-1, Bcl-2, Bcl-xL, and inducible nitric oxide synthase (iNOS) determined by RT-PCR were down-regulated in the Morin groups (p < 0.05). These results indicate that Morin plays a protective role by reducing oxidative stress, inflammation, and apoptosis in the IFOS-induced liver injury in rats.

Probing prodrug metabolism and reciprocal toxicity with an integrated and humanized multi-tissue organ-on-a-chip platform.

Current drug development techniques are expensive and inefficient, partially due to the use of preclinical models that do not accurately recapitulate in vivo drug efficacy and cytotoxicity. To address this challenge, we report on an integrated, in vitro multi-organoid system that enables parallel assessment of drug efficiency and toxicity on multiple 3D tissue organoids. Built in a low-cost, adhesive film-based microfluidic device, these miniaturized structures require less than 200 µL fluid volume and are amenable to both matrix-based 3D cell culture and spheroid aggregate integration, each supported with an in situ photocrosslinkable hyaluronic acid hydrogel. Here, we demonstrate this technology first with a three-organoid device consisting of liver, cardiac, and lung constructs. We show that these multiple tissue types can be kept in common circulation with high viability for 21 days and validate the platform by investigating liver metabolism of the prodrug capecitabine into 5-fluorouracil (5-FU) and observing downstream toxicity in lung and cardiac organoids. Then we expand the integrated system to accommodate six humanized constructs, including liver, cardiac, lung, endothelium, brain, and testes organoids. Following a 14-day incubation in common media, we demonstrate multi-tissue interactions by metabolizing the alkylating prodrug ifosfamide in the liver organoid to produce chloroacetaldehyde and induce downstream neurotoxicity. Our results establish an expandable, multi-organoid body-on-a-chip system that can be fabricated easily and used for the accurate characterization of drug interactions in vitro. STATEMENT OF SIGNIFICANCE: The use of 3-dimensional (3D) in vitro models in drug development has advanced over the past decade. However, with several exceptions, the majority of research studies using 3D in vitro models, such as organoids, employ single tissue types, in isolated environments with no "communication" between different tissues. This is a significant limiting factor because in the human body there is significant signaling between different cells, tissues, and organs. Here we employ a low-cost, adhesive film-based microfluidic device approach, paired with a versatile extracellular matrix-derived hyaluronic acid hydrogel to support integrated systems of 3 and 6 3D organoid and cell constructs. Moreover, we demonstrate an integrated response to drugs, in which downstream toxicity is dependent on the presence of liver organoids.

Safe decontamination of cytostatics from the nitrogen mustards family. Part one: cyclophosphamide and ifosfamide.

INTRODUCTION: Macrocrystalline oxides of alkaline earth metals (Mg and Ca) or light metals (Al and Ti) can respond to standard warfare agents such as sulfur mustard, soman, or agent VX. In this paper, we compared the decontamination ability of sodium hydroxide (NaOH) and sodium hypochlorite (NaClO) for nitrogen mustards (cyclophosphamide [CP] and ifosfamide [IFOS]) with a new procedure using a destructive sorbent based on nanocrystalline and nanodispersive titanium dioxide (TiO2) as a new efficient and cheap material for complete decontamination of surfaces. METHODS: Titanium (IV) dioxide nanoparticles were prepared by the homogeneous hydrolysis of titanium(IV) oxysulfate (TiOSO4) with urea. The as-prepared TiO2 nanoparticles were used for the fast and safe decontamination of cytostatics from the nitrogen mustard family (CP and IFOS) in water. The adsorption-degradation process of cytostatics in the presence of TiO2 was compared with decontamination agents (0.01 M solution of sodium hydroxide and 5% solution of sodium hypochlorite). The mechanism of the decontamination process and the degradation efficiency were determined by high-performance liquid chromatography with mass spectrometry. RESULTS: It was demonstrated that a 0.01 M solution of sodium hydroxide (NaOH) decomposes CP to 3-((amino(bis(2-chloroethyl)amino)phosphoryl)oxy)propanoic acid and sodium hypochlorite formed two reaction products, namely, IFOS and 4-hydroxy-cyclophosphamide. IFOS is cytotoxic, and 4-hydroxy-cyclophosphamide is a known metabolite of CP after its partial metabolism by CYP/CYP450. IFOS degrades in the pres¬ence of NaOH to toxic IFOS mustard. Titanium(IV) dioxide nanoparticles adsorbed on its surface CP after 5 minutes and on IFOS after 10 minutes. The adsorption-degradation process of CP in water and in the presence of TiO2 led to 4-hydroxy-cyclophosphamide and IFOS, respectively, which decayed to oxidation product 4-hydroxy-ifosfamide. CONCLUSION: Nanodispersive TiO2 is an effective degradation agent for decontamination of surfaces from cytostatics in medical facilities.

Radiosynthesis, molecular modeling studies and biological evaluation of 99mTc-Ifosfamide complex as a novel probe for solid tumor imaging.

PURPOSE: Ifosfamide as a chemotherapeutic drug is used for the treatment of different cancer types. The purpose of this study is the preparation of 99mTc-ifosfamide complex to be evaluated as a potential candidate for tumor imaging. MATERIALS AND METHODS: The radiolabeling of ifosfamide with technetium-99m was carried out by mixing 4mg ifosfamide and 5 µg of SnCl2.2H2O with 400 MBq Na99mTcO4 at pH 9 for 30 min at room temperature. Computer simulation studies were performed using Accelrys Discovery Studio 2.5 operating system to illustrate the interaction of ifosfamide and 99mTc-ifosfamide complexes with DNA. The in-vivo biodistribution of 99mTc-ifosfamide was studied in tumor-bearing Albino mice. RESULTS: A new 99mTc-ifosfamide complex was synthesized with a good radiochemical yield of 90.3 ± 2.1% under the optimized conditions and exhibited in-vitro stability up to 2 h. Biodistribution studies showed good uptake in tumor site and high uptake in tumor site with T/NT ∼3 after 60 min post-injection. Besides, the molecular docking study confirmed that the complexation of ifosfamide with technetium-99m does not abolish its binding to the target receptor. CONCLUSION: These promising results afford a new radiopharmaceutical that could be used as a potential tumor imaging.

A Biomimetic Human Gut-on-a-Chip for Modeling Drug Metabolism in Intestine.

Drug metabolism in the intestine is considered to substantially contribute to the overall first-pass metabolism, which has been neglected for a long time. It is highly desirable to develop a reliable model to evaluate drug metabolism in the intestine in vitro. In this work, we made the first attempt to develop a biomimetic human gut-on-a-chip for modeling drug metabolism in intestine. In this chip, constant flow, together with porous nitrocellulose membrane and collagen I, mimics an in vivo-like intestinal microenvironment. The Caco-2 cells grown in the chip formed a compact intestinal epithelial layer with continuous expression of the tight junction protein, ZO-1. Furthermore, higher gene expression of villin, sucrase-isomaltase, and alkaline phosphatase demonstrated that cells in the biomimetic human gut-on-a-chip device were more mature with near-physiological functions compared to the control on planar substrate. In particular, cellular metabolic activity was assessed on different substrates, indicating higher metabolic efficiency of ifosfamide and verapamil in the biomimetic human gut-on-a-chip model. Taken together, our results suggested that this biomimetic human gut-on-a-chip promoted the differentiation of intestinal cells with enhanced functionality by creating a biomimetic 3D microenvironment in vitro. It might offer a bioactive, low-cost, and flexible in vitro platform for studies on intestinal metabolism as well as preclinical drug development.

Possible role of CYP2B6 genetic polymorphisms in ifosfamide-induced encephalopathy: report of three cases.

Ifosfamide (IFA) is a potent alkylating antitumoral agent, but its use is limited by neurological side effects. IFA is a racemic mixture of two enantiomeric forms, R-IFA and S-IFA with a stereoselective metabolism by CYP3A4 and CYP2B6, leading either to bioactive or to toxic pathways. In three consecutive cases of pediatric patients who exhibited IFA-induced encephalopathy (IIE), genotyping of clinically relevant single-nucleotide polymorphisms associated with decreased CYP3A4 and CYP2B6 activities was performed. Genetic investigations revealed the presence of CYP2B6 rs4803419 (C>T) in one patient while the two others carried the CYP2B6*6 allelic variant. All patients carried CYP3A4 wild-type genotype (CYP3A4*1/*1). Because CYP2B6-deficient alleles may be responsible for an increased conversion of S-IFA into neurotoxic metabolites, screening for CYP2B6 polymorphisms may help to avoid IIE and improve clinical outcomes.

Human metabolites and transformation products of cyclophosphamide and ifosfamide: analysis, occurrence and formation during abiotic treatments.

This study describes a gas chromatography-mass spectrometry analytical method for the analysis of cytostatic cyclophosphamide (CP), ifosfamide (IF) and their selected metabolites/transformation products (TPs): carboxy-cyclophosphamide (carboxy-CP), keto-cyclophosphamide (keto-CP) and 3-dechloroethyl-ifosfamide/N-dechloroethyl-cyclophosphamide (N-decl-CP) in wastewater (WW). Keto-cyclophosphamide, CP and IF were extracted with Oasis HLB and N-decl-CP and carboxy-CP with Isolute ENV+ cartridges. Analyte derivatization was performed by silylation (metabolites/TPs) and acetylation (CP and IF). The recoveries and LOQs of the developed method were 58, 87 and 103 % and 77.7, 43.7 and 6.7 ng L(-1) for carboxy-CP, keto-CP and N-decl-CP, respectively. After validation, the analytical method was applied to hospital WW and influent and effluent samples of a receiving WW treatment plant. In hospital WW, levels up to 2690, 47.0, 13,200, 2100 and 178 ng L(-1) were detected for CP, IF, carboxy-CP, N-decl-CP and keto-CP, respectively, while in influent and effluent samples concentrations were below LOQs. The formation of TPs during abiotic treatments was also studied. Liquid chromatography-high-resolution mass spectrometry was used to identify CP and IF TPs in ultrapure water, treated with UV and UV/H2O2. UV treatment produced four CP TPs and four IF TPs, while UV/H2O2 resulted in five CPs and four IF TPs. Besides already known TPs, three novel TPs (CP-TP138a, imino-ifosfamide and IF-TP138) have been tentatively identified. In hospital WW treated by UV/O3/H2O2, none of the target metabolites/TPs resulted above LOQs.

Hydroxylation and N-dechloroethylation of Ifosfamide and deuterated Ifosfamide by the human cytochrome p450s and their commonly occurring polymorphisms.

The hydroxylation and N-dechloroethylation of deuterated ifosfamide (d4IFO) and ifosfamide (IFO) by several human P450s have been determined and compared. d4IFO was synthesized with deuterium at the alpha and alpha' carbons to decrease the rate of N-dechloroethylation and thereby enhance hydroxylation of the drug at the 4' position. The purpose was to decrease the toxic and increase the efficacious metabolites of IFO. For all of the P450s tested, hydroxylation of d4IFO was improved and dechloroethylation was reduced as compared with nondeuterated IFO. Although the differences were not statistically significant, the trend favoring the 4'-hydroxylation pathway was noteworthy. CYP3A5 and CYP2C19 were the most efficient enzymes for catalyzing IFO hydroxylation. The importance of these enzymes in IFO metabolism has not been reported previously and warrants further investigation. The catalytic ability of the common polymorphisms of CYP2B6 and CYP2C9 for both reactions were tested with IFO and d4IFO. It was determined that the commonly expressed polymorphisms CYP2B6*4 and CYP2B6*6 had reduced catalytic ability for IFO compared with CYP2B6*1, whereas CYP2B6*7 and CYP2B6*9 had enhanced catalytic ability. As with the wild-type enzymes, d4IFO was more readily hydroxylated by the polymorphic variants than IFO, and d4IFO was not dechloroethylated by any of the polymorphic forms. We also assessed the use of specific inhibitors of P450 to favor hydroxylation in human liver microsomes. We were unable to separate the pathways with these experiments, suggesting that multiple P450s are responsible for catalyzing both metabolic pathways for IFO, which is not observed with the closely related drug cyclophosphamide.

Activation of the anticancer drugs cyclophosphamide and ifosfamide by cytochrome P450 BM3 mutants.

Cyclophosphamide (CPA) and ifosfamide (IFA) are widely used anticancer agents that require metabolic activation by cytochrome P450 (CYP) enzymes. While 4-hydroxylation yields DNA-alkylating and cytotoxic metabolites, N-dechloroethylation results in the generation of neuro- and nephrotoxic byproducts. Gene-directed enzyme prodrug therapies (GDEPT) have been suggested to facilitate local CPA and IFA bioactivation by expressing CYP enzymes within the tumor cells, thereby increasing efficacy. We screened bacterial CYP BM3 mutants, previously engineered to metabolize drug-like compounds, for their ability to catalyze 4-hydroxylation of CPA and IFA. Two CYP BM3 mutants showed very rapid initial bioactivation of CPA and IFA, followed by a slower phase of product formation. N-dechloroethylation by these mutants was very low (IFA) to undetectable (CPA). Using purified CYP BM3 as an extracellular bioactivation tool, cytotoxicity of CPA and IFA metabolism was confirmed in U2OS cells. This novel application of CYP BM3 possibly provides a clean and catalytically efficient alternative to liver microsomes or S9 for the study of CYP-mediated drug toxicity. To our knowledge, the observed rate of CPA and IFA 4-hydroxylation by these CYP BM3 mutants is the fastest reported to date, and might be of potential interest for CPA and IFA GDEPT.

Preactivated oxazaphosphorines designed for isophosphoramide mustard delivery as bulk form or nanoassemblies: synthesis and proof of concept.

Oxazaphosphorines are alkylating agents used in routine clinical practices for treatment of cancer for many years. They are antitumor prodrugs that require cytochrome P450 bioactivation leading to 4-hydroxy derivatives. In the case of ifosfamide (IFO), the bioactivation produces two toxic metabolites: acrolein, a urotoxic compound, concomitantly generated with the isophosphoramide mustard; and chloroacetaldehyde, a neurotoxic and nephrotoxic compound, arising from the oxidation of the side chains. To improve the therapeutic index of IFO, we have designed preactivated IFO derivatives with the covalent binding of several O- and S-alkyl moieties including polyisoprenoid groups at the C-4 position of the oxazaphosphorine ring to avoid cytochrome bioactivation favoring the release of the active entity and limiting the chloroacetaldehyde release. Thanks to the grafted terpene moieties, some of these new conjugates demonstrated spontaneous self-assembling properties into nanoassemblies when dispersed in water. The cytotoxic activities on a panel of human tumor cell lines of these novel oxazaphosphorines, in bulk form or as nanoassemblies, and the release of 4-hydroxy-IFO from these preactivated IFO analogues in plasma are reported.

The nephrotoxic Ifosfamide-metabolite chloroacetaldehyde interferes with renal extracellular matrix homeostasis.

BACKGROUND/AIMS: Chronic renal proximal tubule dysfunction after therapy with the antineoplastic agent ifosfamide (IFO) is often attributed to the metabolite chloroacetaldehyde (CAA). Chronic IFO-nephropathy is reported to result in tubulointerstitial fibrosis and inflammation. METHODS: To elucidate possible effects of CAA on extracellular matrix homeostasis, we investigated the action of CAA on markers of extracellular matrix (ECM) homeostasis in human proximal tubule cells (RPTEC) by use of direct ELISA for extracellular collagens and gelatin zymography. RESULTS: An increase in type III collagen and a decrease in type IV collagen abundance in the media of RPTEC could be observed after exposure to CAA in clinically relevant concentrations. CAA increased intracellular type III and decreased intracellular type IV collagen. MMP-2 activity was decreased but MMP-9 activity unchanged. The enhanced CAA-induced collagen III formation could be attenuated by the intracellular Ca(2+)-chelator BAPTA-AM, the PKA-antagonist H-89 and by extracellular acidification. CAA-induced collagen III abundance was enhanced by db-cAMP and IBMX and by protein overload. CONCLUSIONS: CAA exerts profibrotic effects on RPTEC dependent on Ca(2+) and cAMP/PKA-signaling. These effects are enhanced by additional protein burden and attenuated by acidification. © 2014 S. Karger AG, Basel.

Extravascular use of drug-eluting beads: a promising approach in compartment-based tumor therapy.

Intraperitoneal carcinomatosis (PC) may occur with several tumor entities. The prognosis of patients suffering from PC is usually poor. Present treatment depends on the cancer entity and includes systemic chemotherapy, radiation therapy, hormonal therapy and surgical resection. Only few patients may also benefit from hyperthermic intraperitoneal chemotherapy with a complete tumor remission. These therapies are often accompanied by severe systemic side-effects. One approach to reduce side effects is to target chemotherapeutic agents to the tumor with carrier devices. Promising experimental results have been achieved using drug-eluting beads (DEBs). A series of in vitro and in vitro experiments has been conducted to determine the suitability of their extravascular use. These encapsulation devices were able to harbor CYP2B1 producing cells and to shield them from the hosts immune system when injected intratumorally. In this way ifosfamide--which is transformed into its active metabolites by CYP2B1--could be successfully targeted into pancreatic tumor growths. Furthermore DEBs can be used to target chemotherapeutics into the abdominal cavity for treatment of PC. If CYP2B1 producing cells are proven to be save for usage in man and if local toxic effects of chemotherapeutics can be controlled, DEBs will become promising tools in compartment-based anticancer treatment.

[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.

A molecular model of the enantioselective liquid chromatographic separation of (R,S)-ifosfamide and its N-dechloroethylated metabolites on a teicoplanin aglycon chiral stationary phase.

The enantioselective separations of the chiral oxazaphosphorines (R,S)-ifosfamide (IF), (R,S)-2-N-dechloroethyl-IF (2-DCE-IF) and (R,S)-3-N-dechloroethyl-IF (3-DCE-IF) were achieved on teicoplanin-based chiral stationary phase using isopropanol:methanol (60:40, v/v) as the mobile phase. Computational models of the teicoplanin and teicoplanin aglycon (TAG) chiral selectors were constructed and used in docking experiments to examine the chiral recognition mechanism associated with the observed resolutions. Initial data showed no significant differences between the simulated selector-selectand complexes using teicoplanin and TAG, and the full study was conducted using TAG. The data from the study indicate that hydrophobic interactions arise between the chlorine atom present in the cholorethyl moieties of the oxazaphosphorine molecules and hydrophobic pockets within the TAG basket and that these interactions anchored and positioned the selectands within the selector-selectand complexes. The complexes were stabilized through the formation of a network of hydrogen bond and cation-π interactions, in which the latter involved the phosphorous atom of the phosphoramide moiety and aromatic components of the TAG aglycon basket. The chirality of the oxazaphosphorine molecule determined the number and strength of the stabilizing interactions which resulted in significant differences in the relative mean binding energies between the complexes formed by the (R) and (S) enantiomers of the selectands. These differences were consistent with the observed chromatographic enantioselectivity and suggest a multi-step chrial recognition mechanism involving the tethering of the selectand to the selector followed by conformational adjustments and stabilization of the selectand-selector complex.

Comparison of the novel HK-2 human renal proximal tubular cell line with the standard LLC-PK1 cell line in studying drug-induced nephrotoxicity.

Established cell lines are widely used as in vitro models in toxicology studies. The choice of an appropriate cell line is critical when performing studies to elucidate drug-induced toxicity in humans. The porcine renal proximal tubular cell line LLC-PK1 is routinely used to study the nephrotoxic effects of drugs in humans. However, there are significant interspecies differences in drug pharmacokinetics and pharmacodynamics. The objective of this study was to determine whether the human renal proximal tubular cell line HK-2 is an acceptable model to use when performing in vitro toxicity studies to predict effects in humans. We examined 2 nephrotoxic agents, ifosfamide (IFO) and acyclovir, that exhibit different clinical nephrotoxic patterns. HK-2 cells metabolized IFO to its nephrotoxic metabolite, chloroacetaldehyde (CAA). Acyclovir induced a concentration-dependent decrease in HK-2 cell viability, suggesting that acyclovir may induce direct insult to renal proximal tubular cells. The results support clinical pathology data in humans and suggest that HK-2 cells are a suitable model to use in in vitro toxicity studies to determine drug-induced nephrotoxicity in humans.