Particular aspects of platinum compounds used at present in cancer treatment

Towards biomarker-dependent individualized chemotherapy: exploring cell-specific differences in oxaliplatin-DNA adduct distribution using accelerator mass spectrometry

Oxaliplatin is a third-generation platinum-based anticancer drug that is currently used in the treatment of metastatic colorectal cancer. Oxaliplatin, like other platinum-based anticancer drugs such as cisplatin and carboplatin, is known to induce apoptosis in tumor cells by binding to nuclear DNA, forming monoadducts, and intra- and interstrand diadducts. Previously, we reported an accelerator mass spectrometry (AMS) assay to measure the kinetics of oxaliplatin-induced DNA damage and repair [Hah, S. S.; Sumbad, R. A.; de Vere White, R. W.; Turteltaub, K. W.; Henderson, P. T. Chem. Res. Toxicol.2007, 20, 1745]. Here, we describe another application of AMS to the measurement of oxaliplatin-DNA adduct distribution in cultured platinum-sensitive testicular (833K) and platinum-resistant breast (MDA-MB-231) cancer cells, which resulted in elucidation of cell-dependent differentiation of oxaliplatin-DNA adduct formation, implying that differential adduction and/or accumulation of the drug in cellular DNA may be responsible for the sensitivity of cancer cells to platinum treatment. Ultimately, we hope to use this method to measure the intrinsic platinated DNA adduct repair capacity in cancer patients for use as a biomarker for diagnostics or a predictor of patient outcome.

Silencing Fas-associated phosphatase 1 expression enhances efficiency of chemotherapy for colon carcinoma with oxaliplatin

AIM: To investigate whether silencing Fas-associated phosphatase 1 (FAP-1) expression enhances the efficiency of chemotherapy for colon carcinoma with oxaliplatin.

METHODS: Expression of FAP-1 in mRNA and protein was detected by reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry. Small interfering RNA (siRNA) was designed according to the FAP-1 mRNA sequence. Cell proliferation was evaluated by methyl thiazolyl tetrazolium (MTT) assay. Anenxin V- and propidine iodine (PI) were assayed by flow cytometry for the detection of apoptosis.

RESULTS: The expression of FAP-1 was increased in SW480 cells after chemotherapy with oxaliplatin. Transfection of FAP-1 siRNA into SW480 cells silenced the expression of FAP-1 and consequently abolished the inhibitory function of Fas/FasL-mediated apoptosis pathway, thus increasing the efficacy of chemotherapy for colon carcinoma with oxaliplatin.

CONCLUSION: RNA interference combined with conventional chemotherapy is more effective against colon cancer.

Live cell cytotoxicity studies: documentation of the interactions of antitumor active dirhodium compounds with nuclear DNA

The promising antitumor activity of dirhodium complexes has been known for over 30 years. There remains, however, a general lack of understanding of their activity in cellulo. In this study, we report the DNA interactions and activity in living cells of six monosubstituted dirhodium(II,II) complexes of general formula [Rh(2)(mu-O(2)CCH(3))(2)(eta(1)-O(2)CCH(3))(L)(CH(3)OH)](+), where L = bpy (2,2'-bipyridine) (1), phen (1,10-phenanthroline) (2), dpq (dipyrido[3,2-f:2',3'-h]quinoxaline) (3), dppz (dipyrido[3,2-a:2',3'-c]phenazine) (4), dppn (benzo[i]dipyrido[3,2-a:2',3'-c]phenazine) (5), and dap (4,7-dihydrodibenzo[de,gh][1,10]phenanthroline) (6). DNA interactions were investigated by UV/visible spectroscopy, relative viscosity measurements, and electrophoretic mobility shift assay. These measurements indicate that compound 5 exhibits the strongest interaction with DNA. Compound 5 also causes the most damage to DNA after cellular internalization, as evaluated by the alkaline comet assay. Compound 5, however, is not the most effective at inhibiting cell viability of the human cancer cells HeLa and COLO-316. The greater hydrophobicity of 5 as compared to that of 4, which is the most effective compound in the series, hinders its ability to reach its cellular target(s). Data from modulation studies of glutathione using N-acetylcysteine and L-buthionine-sulfoximine indicate that changes in glutathione levels do not affect the activity of these particular dirhodium complexes. These results suggest that glutathione is not the only agent involved in the deactivation of these dirhodium complexes.

In vitro and in vivo optimization of an anti-glioma modality based on synchrotron X-ray photoactivation of platinated drugs

For the past 5 years, a radio-chemotherapy approach based on the photoactivation of platinum atoms (PAT-Plat) consisting of treating tumors with platinated compounds and irradiating them above the platinum K edge (78.4 keV) has been developed at the European Synchrotron Radiation Facility (Grenoble, France). Compared to other preclinical modalities, PAT-Plat provides the highest survivals of rats bearing the rodent F98 glioma. However, further investigations are required to optimize its efficiency and to allow its clinical application. Here we examined in vitro and in vivo whether monochromatic X rays are more efficient than high-energy photons in producing the PAT-Plat effect by measuring DNA double-strand breaks (DSBs) and survival of glioma-bearing rats and whether an increase in the platinum concentration in the tumor results in increased rat survival. DSBs were assessed by pulsed-field gel electrophoresis with different DNA fragment migration programs and with gamma-H2AX immunofluorescence. In vivo, F98 glioma cells were injected intracerebrally, treated with a single intracranial injection of cisplatin or carboplatin 13 days after tumor implantation, and irradiated the day after with 78.8 keV X rays or 6 MV photons. Our results indicate that 78.8 keV X rays are more efficient than high-energy photons at producing the PAT-Plat effect. At low concentrations, cisplatin is more efficient than carboplatin; this is likely due to more efficient DNA binding and DSB repair inhibition. High concentrations of carboplatin inside tumors do not necessarily lead to protracted survival of rats. The therapeutic benefit of anti-glioma synchrotron strategies appears to be correlated with the percentage of unrepaired DSBs but not with the number of DSBs induced.

Chronotoxicity of Nedaplatin in Rats

Chronotoxicologic profiles of nedaplatin, a platinum compound, were evaluated in rats maintained under a 12 light/12 dark cycle with light from 07:00h to 19:00 h. Nedaplatin (5 mg/kg) was injected intravenously, once a week for 5 weeks at 08:00h or 20:00h. The suppression of body weight gain and reduction of creatinine clearance were significantly greater with the 20:00h than 08:00h treatment. Accumulation of nedaplatin in the renal cortex and bone marrow were also greater with 20:00 h treatment. There were significant relationships between the nedaplatin content in the kidney and bone marrow and degree of injury to each. These results suggest that the nedaplatin-induced toxicity depends on its dosing-time, and it is greater with treatment at 20:00 h, during the active phase. The dosing-time dependency in the accumulation of nedaplatin in the tissue of the organs might be involved in this chronotoxicologic phenomenon.

Anti-cancer drugs interfere with intracellular calcium signaling

(Neuro-)toxicity of metal and metal compounds is frequently highlighted. While specific metals or metal compounds are essential for cellular function, other metals are toxic and/or carcinogens. Metals can trigger accidental cell death in the form of necrosis, or activate programmed cell death in the form of apoptosis. The aim of anti-cancer therapy is induction of apoptosis in tumor cells. Therefore, there is an interesting twist in the toxicity of metals and metal compounds (e.g., arsenic trioxide, cisplatin); since they have a higher specificity to induce apoptosis in cancer cells (possibly due to the high turnover in these cells) they are used to cure some forms of cancer. A body of evidence suggests that second messengers, such as modulations in the intracellular calcium concentration, could be involved in metals induced toxicity as well as in the beneficial effects shown by anti-cancer drugs. Here we review the influence on calcium homeostasis induced by some metallic compounds: cisplatin, arsenic trioxide and trimethyltin chloride.

The role of MMP7 and its cross-talk with the FAS/FASL system during the acquisition of chemoresistance to oxaliplatin

Background

The efficacy of oxaliplatin in cancer chemotherapy is limited by the development of drug resistance. MMP7 has been related to the loss of tumor cell response to cytotoxic agents although the exact mechanism is not fully understood. Moreover, MMP7 is an independent prognosis factor for survival in patients with colorectal cancer. The aim of the present study was to analyze the role of MMP7 and its cross-talk with the Fas/FasL system during the acquisition of oxaliplatin resistance in colon cancer cells.

Principal Findings

For this purpose we have developed three different oxaliplatin-resistant cell lines (RHT29, RHCT116 p53^+/+, RHCT116 p53^−/−) from the parental HT29, HCT116 p53^+/+ and HCT116 p53^−/− colon cancer cells. MMP7 basal expression was higher in the resistant compared to the parental cell lines. MMP7 was also upregulated by oxaliplatin in both HT29 (p53 mutant) and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Inhibition of MMP by 1,10-phenantroline monohydrate or siRNA of MMP7 restores cell sensitivity to oxaliplatin-induced apoptosis in both HT29 and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Some of these effects are caused by alterations in Fas receptor. Fas is upregulated by oxaliplatin in colon cancer cells, however the RHT29 cells treated with oxaliplatin showed a 3.8-fold lower Fas expression at the cell surface than the HT29 cells. Decrease of Fas at the plasma membrane seems to be caused by MMP7 since its inhibition restores Fas levels. Moreover, functional analysis of Fas demonstrates that this receptor was less potent in inducing apoptosis in RHT29 cells and that its activation induces MAPK signaling in resistant cells.

Conclusions

Taking together, these results suggest that MMP7 is related to the acquisition of oxaliplatin-resistance and that its inhibition restores drug sensitivity by increasing Fas receptor. Furthermore, Fas undergoes a change in its functionality in oxaliplatin-resistant cells inducing survival pathways instead of apoptotic signals.

Phase I study of chemoradiation with nedaplatin and ifosfamide in patients with advanced squamous cell carcinoma of the uterine cervix

Cisplatin and ifosfamide are considered among the most active drugs in both neoadjuvant and salvage treatments for patients with cervical cancer. Nedaplatin is an analog of cisplatin and it exhibits lesser nephrotoxicity, neurotoxicity, and gastrointestinal toxicity than cisplatin. This study aimed to determine the recommended dosage of nedaplatin plus ifosfamide chemoradiotherapy for advanced squamous cell carcinoma (SCC) of the uterine cervix. Beginning with a dose of 65 mg/m2, nedaplatin (day 1) combined with ifosfamide 1 g/m2 (days 1–5) was designed to be administered for three cycles (minimum: two cycles); its dose was gradually escalated up to 80 mg/m2. Dose-limiting toxicity (DLT) was defined as a more than 7-day delay in the planned radiation therapy and/or planned chemotherapy (prior to the completion of two cycles) due to toxicity. Chemotherapy was not interrupted prior to the completion of two cycles in any patients. Of the 12 patients, 11 received three cycles of chemotherapy. DLT did not occur in any patient. We confirmed a clinical complete response (CR) in ten and partial response (PR) in two patients. The median follow-up period was 39 months (range: 18–57 months). Ten patients (83%) were alive and disease free, one patient was alive with disease, and only one patient died due to the disease. Nedaplatin and ifosfamide combination chemotherapy is a feasible and active chemoradiation strategy for patients with advanced SCC of the uterine cervix. With the ifosfamide dose fixed to 1 g/m2, the recommended nedaplatin dosage was determined to be 80 mg/m2 to be administered for three cycles.

Bioactive fragments synergically involved in the design of new generation Pt(ii) and Pd(ii)-based anticancer compounds

New Pt(ii) and Pd(ii) complexes with the metal center coordinated to two different chelating ligands, tropolone (trop) and dihexadecyl-2,2'-bipyridine-4,4'-dicarboxylate bipyridine (bipy), [(bipy)M(trop)][CF(3)SO(3)], have been synthesized and their biological evaluation has been performed demonstrating a remarkable cytotoxic activity in vitro against the human prostate DU145 and hormone-sensitive LNCaP cells lines. Moreover, for the Pt(ii) derivative, the molecular structure has been determined by single-crystal X-ray diffraction and computational analysis on the hydrolysis reaction mechanisms have been performed by density functional theory (DFT) calculations, in order to correlate molecular structure, biological activity and mechanism of action of this new class of complexes based on two different bioactive fragments.

The delivery of platinum drugs from thermosensitive hydrogels containing different ratios of chitosan

New thermosensitive hydrogels of poly(N-isopropylacrylamide) (PNIPAAm) with chitosan (CPN) were prepared and evaluated for use in the delivery of the platinum drugs, cisplatin and carboplatin. The effects of polymers containing different ratios of chitosan on the physicochemical and drug release characteristics were examined. The sol-gel transition temperature of the hydrogels was determined by differential scanning calorimetry (DSC) and viscometry. Discrepancies in the transition temperature among the various polymer systems were more pronounced when determined by viscosity compared by DSC, with the CPN showing a higher transition temperature than PNIPAAm. The cross-sectional structure and surface topography of the hydrogels were examined by scanning electronic microscopy (SEM) and atomic force microscopy (AFM), respectively. The incorporation of chitosan further increased the entanglement of the hydrogel network. An increase in the chitosan ratio in the polymers (CPN-H) also increased the cross-linking structure. A smoother surface of hydrogel matrices was observed for CPN compared with PNIPAAm. All hydrogels tested significantly reduced drug release compared with an aqueous solution. The release rate of platinum drugs from PNIPAAm was retarded at the late stage. CPN matrices could continuously deliver platinum drugs during the experiment. The rate of release from CPN-H was generally slower than that from hydrogels and had a lower chitosan ratio (CPN-L), presumably due to the more-tortuous pathways in the hydrogels. Thermosensitive hydrogels like those prepared in this study may be a promising carrier for the delivery of platinum drugs, as the drug release can be controlled and sustained using CPN networks.

Photodynamic activity of platinum(IV) chloride surface-modified TiO2 irradiated with visible light

The visible light-induced phototoxicity of titanium dioxide modified with platinum(IV) chloride complexes, [TiO2/PtCl4], was tested. In vitro experiments with the mouse melanoma cells (S-91) have demonstrated phototoxicity of the [TiO2/PtCl4] material. Detection of efficiently generated various reactive oxygen species (.OH, O2. -, H2O2, 1O2) and also reactive chlorine species has proven the photodynamic activity of the tested material, induced by visible light (lambda>455 nm). The cellular death (recognized as a necrosis) is a result of the cell membrane peroxidation.

The application of inductively coupled plasma mass spectrometry in clinical pharmacological oncology research

Metal-based anticancer agents are frequently used in the treatment of a wide variety of cancer types. The monitoring of these anticancer agents in biological samples is important to understand their pharmacokinetics, pharmacodynamics, and metabolism. In addition, determination of metals originating from anticancer agents is relevant to assess occupational exposure of health care personnel working with these drugs. The high sensitivity of inductively coupled plasma mass spectrometry (ICP-MS) has resulted in an increased popularity of this technique for the analysis of metal-based anticancer drugs. In addition to the quantitative analysis of the metal of interest in a sample, ICP-MS can be used as an ultrasensitive metal selective detector in combination with speciation techniques such as liquid chromatography. In the current review we provide a systematic survey of publications describing the analysis of platinum- and ruthenium-containing anticancer agents using ICP-MS, focused on the determination of total metal concentrations and on the speciation of metal compounds in biological fluids, DNA- and protein-adducts, and environmental samples. We conclude that ICP-MS is a powerful tool for the quantitative analysis of metal-based anticancer agents from multiple sample sources.

Pharmacogenomics in colorectal cancer: The first step for individualized-therapy

Interindividual differences in the toxicity and response to anticancer therapies are currently observed in practically all available treatment regimens. A goal of cancer therapy is to predict patient response and toxicity to drugs in order to facilitate the individualization of patient treatment. Identification of subgroups of patients that differ in their prognosis and response to treatment could help to identify the best available drug therapy according the genetic profile. Several mechanisms have been suggested to contribute to chemo-therapeutic drug resistance: amplification or overexpression of membrane transporters, changes in cellular proteins involved in detoxification or in DNA repair, apoptosis and activation of oncogenes or tumor suppressor genes. Colorectal cancer (CRC) is regarded as intrinsically resistant to chemotherapy. Several molecular markers predictive of CRC therapy have been included during the last decade but their results in different studies complicate their application in practical clinical. The simultaneous testing of multiple markers predictive of response could help to identify more accurately the true role of these polymorphisms in CRC therapy. This review analyzes the role of genetic variants in genes involved in the action mechanisms of the drugs used at present in colorectal cancer.

Organic cation transporters are determinants of oxaliplatin cytotoxicity

Although the platinum-based anticancer drugs cisplatin, carboplatin, and oxaliplatin have similar DNA-binding properties, only oxaliplatin is active against colorectal tumors. The mechanisms for this tumor specificity of platinum-based compounds are poorly understood but could be related to differences in uptake. This study shows that the human organic cation transporters (OCT) 1 and 2 (SLC22A1 and SLC22A2) markedly increase oxaliplatin, but not cisplatin or carboplatin, accumulation and cytotoxicity in transfected cells, indicating that oxaliplatin is an excellent substrate of these transporters. The cytotoxicity of oxaliplatin was greater than that of cisplatin in six colon cancer cell lines [mean +/- SE of IC(50) in the six cell lines, 3.9 +/- 1.4 micromol/L (oxaliplatin) versus 11 +/- 2.0 micromol/L (cisplatin)] but was reduced by an OCT inhibitor, cimetidine, to a level similar to, or even lower than that of, cisplatin (29 +/- 11 micromol/L for oxaliplatin versus 19 +/- 4.3 micromol/L for cisplatin). Structure-activity studies indicated that organic functionalities on nonleaving groups coordinated to platinum are critical for selective uptake by OCTs. These results indicate that OCT1 and OCT2 are major determinants of the anticancer activity of oxaliplatin and may contribute to its antitumor specificity. They also strongly suggest that expression of OCTs in tumors should be investigated as markers for selecting specific platinum-based therapies in individual patients. The development of new anticancer drugs, specifically targeted to OCTs, represents a novel strategy for targeted drug therapy. The results of the present structure-activity studies indicate specific tactics for realizing this goal.

Characterization of oxaliplatin-DNA adduct formation in DNA and differentiation of cancer cell drug sensitivity at microdose concentrations

(trans-R, R)-1,2-diaminocyclohexaneoxalatoplatinum(II) (oxaliplatin) is a recently approved platinum analogue for use in the chemotherapy of metastatic colorectal cancer. Like many cytotoxic drugs, oxaliplatin exerts its antitumor effects by covalent modification of DNA. We report an accelerator mass spectrometry (AMS) assay to measure the kinetics of oxaliplatin-induced DNA damage and repair. We determined the apparent rate of oxaliplatin adduction to salmon sperm DNA. The oxaliplatin-DNA adduct distribution was further investigated at the nucleoside level by HPLC-AMS. Cultured platinum-sensitive testicular (833K) and platinum-resistant breast and bladder (MDA-MB-231 and T24, respectively) cancer cells were incubated with a subpharmacological concentration of oxaliplatin (0.2 microM). Both cellular and DNA radiocarbon contents in the drug-sensitive testicular cells had approximately twice the area under the curve as compared to the more platinum-resistant cell lines, implying that differential accumulation of the drug may be responsible for the sensitivity of cancer cells to platinum treatment. The lowest concentration of radiocarbon measured was approximately 1+/-0.1 amol/microg of DNA, when assaying 1 microg of DNA. This sensitivity for measuring oxaliplatin-DNA adducts is the highest reported to date. The sensitivity offered by this method may be applicable to other DNA-damaging drugs, metabolisms studies, and diagnostics development.

Fate of cancerostatic platinum compounds in biological wastewater treatment of hospital effluents

The present work focuses on the fate of two cancerostatic platinum compounds (CPC), cisplatin and carboplatin, as well as of two inorganic platinum compounds, [PtCl(4)](2-) and [PtCl(6)](2-) in biological wastewater treatment. Laboratory experiments modelling adsorption of these compounds onto activated sludge showed promising specific adsorption coefficients K(D) and K(OC) and Freundlich adsorption isotherms. However, the adsorption properties of the investigated substances were differing significantly. Adsorption decreased following the order cisplatin>[PtCl(6)](2-)>[PtCl(4)](2-)>carboplatin. LogK(D)-values were ranging from 2.5 to 4.3 , logK(OC) from 3.0 to 4.7. A pilot membrane bioreactor system (MBR) was installed in a hospital in Vienna and fed with wastewater from the oncologic in-patient treatment ward to investigate CPC-adsorption in a sewage treatment plant. During three monitoring periods Pt-concentrations were measured in the influent (3-250 microg l(-1) Pt) and the effluent (2-150 microgl(-1) Pt) of the treatment plant using ICP-MS. The monitoring periods (duration 30d) revealed elimination efficiencies between 51% and 63% based on averaged weekly input-output budgets. The derived logK(D)-values and logK(OC)-values ranged from 2.4 to 4.8 and from 2.8 to 5.3, respectively. Species analysis using HPLC-ICP-MS proofed that mainly carboplatin was present as intact drug in the influent and--due to low logK(D)--in the effluent of the MBR.

The influence of temperature on antiproliferative effects, cellular uptake and DNA platination of the clinically employed Pt(II)-drugs

Cellular uptake of a drug is one of the most important factors influencing its pharmacodynamics and pharmacokinetics. Our laboratory has previously studied platinum uptake following cisplatin, carboplatin and oxaliplatin treatment at sub-lethal doses of selected tumour cell lines. Here we report on the influence of temperature on dose-dependent antiproliferative effects, cellular uptake and DNA platination of these platinum-based drugs tested on MCF-7 human mammary carcinoma cell line. Inductively coupled plasma-mass spectrometry (ICP-MS) technique has been chosen to perform Pt determinations on cells treated with drug concentrations similar with those usually found in vivo in human plasma. The high sensitivity and analytical rapidity of this technique made possible to carry out a very large amount of Pt determinations (about 300) necessary for this study. Hyperthermia (43 degrees C) proved a synergistic effect with cisplatin on cell growth inhibition, while only an additive effect was demonstrated for carboplatin and oxaliplatin. This behaviour might be explained by the higher DNA platination ratio between data at 43 and 37 degrees C of cisplatin with respect to those of carboplatin and oxaliplatin.

Pharmacodynamic model for chemotherapy-induced anemia in rats

Anticancer agents often cause bone marrow toxicity resulting in progressive anemia which may influence the therapeutic effects of erythropoietic-stimulating agents. The objective of this study was to develop a pharmacodynamic (PD) model to describe chemotherapy-induced anemia in rats. Anemia was induced in male Wistar rats with a single intravenous (i.v.) injection of 60 mg/kg carboplatin. Hematological responses including reticulocytes, red blood cells (RBC), hemoglobin, and endogenous rat erythropoietin (EPO) were measured for up to 4 weeks. A catenary, lifespan-based, indirect response model served as a basic PD model to represent erythroid cellular populations in the bone marrow and blood involved in erythropoiesis. The model assumed that actively proliferating progenitor cells in the bone marrow are sensitive to anti-cancer agents and subject to an irreversible removal process. The removal rate of the target cells is proportional to drug activity concentrations and the cell numbers. An additional RBC loss from the circulation resulting from thrombocytopenia was described by a first-order process. The turnover process of rat EPO and EPO-mediated feedback inhibition mechanism regulated by hemoglobin changes were incorporated. Reticulocyte counts decreased rapidly and reached a nadir by day 3 after administration of carboplatin and returned to the baseline by day 13. This was followed by a gradual increase and the rebound peak occurred at about day 15. The hemoglobin nadir was approximately 9 g/dl observed at about 11-13 days compared to its normal value of 13 g/dl and hemoglobin returned to the baseline by day 30. The increase in endogenous rat EPO mirrored inversely hemoglobin changes and the maximum increase was observed soon after the hemoglobin nadir. The carboplatin-treated rats exhibited progressive anemia. The proposed model adequately described the time course of hematological changes after carboplatin in rats and can be a useful tool to explore potential strategies for the management of anemia caused by chemotherapy.

Combined modalities of resistance in an oxaliplatin-resistant human gastric cancer cell line with enhanced sensitivity to 5-fluorouracil

To identify mechanisms underlying oxaliplatin resistance, a subline of the human gastric adenocarcinoma TSGH cell line, S3, was made resistant to oxaliplatin by continuous selection against increasing drug concentrations. Compared with the parental TSGH cells, the S3 subline showed 58-fold resistance to oxaliplatin; it also displayed 11-, 2-, and 4.7-fold resistance to cis-diammine-dichloroplatinum (II) (CDDP), copper sulphate, and arsenic trioxide, respectively. Interestingly, S3 cells were fourfold more susceptible to 5-fluorouracil-induced cytotoxicity due to downregulation of thymidylate synthase. Despite elevated glutathione levels in S3 cells, there was no alteration of resistant phenotype to oxaliplatin or CDDP when cells were co-treated with glutathione-depleting agent, l-buthionine-(S,R)-sulphoximine. Cellular CDDP and oxaliplatin accumulation was decreased in S3 cells. In addition, amounts of oxaliplatin- and CDDP–DNA adducts in S3 cells were about 15 and 40% of those seen with TSGH cells, respectively. Western blot analysis showed increased the expression level of copper transporter ATP7A in S3 cells compared with TSGH cells. Partial reversal of the resistance of S3 cells to oxaliplatin and CDDP was observed by treating cell with ATP7A-targeted siRNA oligonucleotides or P-type ATPase-inhibitor sodium orthovanadate. Besides, host reactivation assay revealed enhanced repair of oxaliplatin- or CDDP-damaged DNA in S3 cells compared with TSGH cells. Together, our results show that the mechanism responsible for oxaliplatin and CDDP resistance in S3 cells is the combination of increased DNA repair and overexpression of ATP7A. Downregulation of thymidylate synthase in S3 cells renders them more susceptible to 5-fluorouracil-induced cytotoxicity. These findings could pave ways for future efforts to overcome oxaliplatin resistance.

Paclitaxel, ifosfamide, and nedaplatin (TIN) salvage chemotherapy for patients with advanced germ cell tumors

BACKGROUND

The paclitaxel, ifosfamide, and cisplatin regimen has been used to treat metastatic testicular cancer with successful results. We investigated the usefulness of a paclitaxel, ifosfamide, and nedaplatin (TIN) regimen as salvage therapy for patients with advanced testicular germ cell tumors (GCTs).

METHODS

Eight patients with advanced GCTs were treated with TIN. The treatment was performed as salvage therapy for cases refractory to therapies, such as bleomycin, etoposide and cisplatin, and irinotecan with nedaplatin. The TIN regimen consisted of paclitaxel (200 mg/m(2)) by 24-h infusion on day 1, followed by ifosfamide (1.2 g/m(2)) infusions over 2 h on days 2-6, and nedaplatin (100 mg/m(2)) given over 2 h on day 2.

RESULTS

Seven out of eight patients achieved a disease-free status after chemotherapy, followed by surgical resection of the residual tumor. Six of the seven patients have continued to show no evidence of disease after salvage therapy, with a median follow-up period of 27 months, but one patient developed a 'growing teratoma syndrome' in the mediastinum 31 months after TIN chemotherapy. All patients developed grade 4 leukocytopenia. However, it could be managed by using granulocyte colony-stimulating factor. Only one patient developed grade 2 sensory neuropathy and no patient developed nephrotoxicity.

CONCLUSION

The TIN regimen was efficacious and well-tolerated as salvage chemotherapy for Japanese patients with advanced GCTs.

Genotoxicity of novel trans-platinum(II) complex with diethyl (pyridin-4-ylmethyl)phosphate in human non-small cell lung cancer cells A549

The dynamic development of metal-containing anticancer drugs has started since the discovery of cis-diamminedichloroplatinum(II). For many years it was believed that trans platinum(II) compounds were non-active as antitumour agents because trans-diamminedichloroplatinum is biologically inactive although it binds to DNA and also forms monoadducts and cross-links. In the present work the ability of a novel platinum(II) compound trans-[PtCl(2)(4-pmOpe)(2)] to induce DNA damage in human non-small cell lung cancer cells A549 was examined using the alkaline comet assay. The obtained results revealed that the novel trans platinum(II) complex induced DNA strand breaks, which were effectively repaired during 2h of post-incubation, and cross-links which remained unrepaired under these test conditions. Apart from that, the modified comet assay with incubation with proteinase K was used to verify the ability of trans-[PtCl(2)(4-pmOpe)(2)] and cis-DDP to form DNA-protein cross-links. It has been proved that only trans-[PtCl(2)(4-pmOpe)(2)] complex exhibits the ability to induce DNA-protein cross-links. The results suggest a different mechanism of action of this compound in comparison to cis-DDP. It seems that trans geometry and the presence of two diethyl (pyridin-4-ylmethyl)phosphates as non-leaving ligands can determine dissimilar properties of the adducts formed on DNA and the different mechanism of action of trans-[PtCl(2)(4-pmOpe)(2)] and in consequence the efficacy in killing cancer cells.

Behavioral and immunohistological assessment of painful neuropathy induced by a single oxaliplatin injection in the rat

In clinical use, a single infusion of oxaliplatin, widely used to treat metastatic colorectal cancer, induces specific sensory neurotoxicity signs triggered or aggravated by exposure to cold. To study the pathophysiology of these symptoms, we developed and characterized an animal model that reproduces the effects of a single intraperitoneal oxaliplatin administration (3, 6 and 12 mg/kg). Significant allodynia and hyperalgesia to cold stimuli were rapidly observed from 24 h to day 5 with a maximum lowering of 76% at t+30 h versus control. Other behavioral assessments revealed rapid persistent mechanical allodynia, but no thermal hyperalgesia or allodynia to heat and no hyperalgesia to mechanical stimuli. An immunohistochemical study in the superficial layers of the spinal dorsal horn revealed a marked increase in substance P immunoreactivity versus controls (12% versus 4%), whereas calcitonin gene-related peptide (CGRP) immunoreactivity was unchanged. This new animal model for the first time closely mimics the effects observed in humans after a single oxaliplatin infusion, especially onset and highly intense sensory disturbances, hypersensitivity to cold with allodynia and hyperalgesia signs. This model may help to elucidate the mechanisms of this thermal hypersensitivity, especially the possible involvement of small-diameter A-fibers in cold allodynia symptoms. These selective effects may clue up the mechanistic basis for the acute oxaliplatin neuropathy leading to a better understanding of the clinical condition and to optimize its treatment.

Cisplatin encapsulated in phosphatidylethanolamine liposomes enhances the in vitro cytotoxicity and in vivo intratumor drug accumulation against melanomas

BACKGROUND

Cisplatin is a potent anticancer drug for treating melanoma.

OBJECTIVE

The aim of this study was to evaluate the possibility of using liposomes, for intratumoral distribution in a melanoma, composed of phosphatidylethanolamine (PE), for its cytotoxicity.

METHOD

The in vitro drug release, in vitro cytotoxicity against melanoma, and in vivo residence time in the tumor of liposome-encapsulated cisplatin were investigated. The liposomes were prepared and characterized in terms of their morphology, size, zeta potential, and drug loading.

RESULT

The size of the PE liposomes attained a level of approximately 100 nm. The concentration of cisplatin encapsulated in PE liposomes was 50-70% dependent on the presence or absence of polyethylene glycol (PEG) derivatives. On the other hand, no or negligible cisplatin molecules were encapsulated in egg phosphatidylcholine (EPC) liposomes. PE liposomes had higher cytotoxicity than classic liposomes or free cisplatin. Images of confocal laser scanning microscopy confirmed the great potency of PE liposomes to deliver cisplatin into cells. The incorporation of PEG derivatives completely inhibited the proliferation of melanoma cells. With in vivo intratumoral administration, the cisplatin concentration in the tumor tissue was maintained at a high level for 72 h after application of the PE liposomes. The PE liposomes delivered cisplatin into the tumor approximately 3.6 times more efficiently than the free drug.

CONCLUSION

These results demonstrate that PE liposomes represent a potentially useful strategy for targeting cisplatin delivery into melanomas.

Behavioral and pharmacological description of oxaliplatin-induced painful neuropathy in rat

We describe an animal model of nociceptive sensory neuropathy induced by repeat intravenous administration of oxaliplatin in which treated animals partly reproduce the characteristic pain symptoms in oxaliplatin-treated patients. We tested the ability of 1, 2 and 4 mg/kg oxaliplatin doses injected twice-weekly for four-and-a-half consecutive weeks to induce a nociceptive peripheral neuropathy in male Sprague-Dawley rats. The behavioral assessment revealed cold allodynia (10 degrees C) and hyperalgesia (4 degrees C) symptoms associated with a mechanical allodynia. The rats maintained a good general clinical status without motor dysfunction. The 2mg/kg oxaliplatin dose and the tail-immersion test in cold water (10 degrees C) were selected to compare pharmacological sensitivity between single administered drugs as morphine, lidocaine, carbamazepine, gabapentin and repeated administration of drugs as clomipramine, venlafaxine, calcium and magnesium solutions. Magnesium solution (90 mg/kg) and venlafaxine (7.5 mg/kg) administration induced an antinociceptive effect whereas gabapentin (300 mg/kg), clomipramine (2.5 mg/kg) and lidocaine (3 and 6 mg/kg) only induced an antiallodynic effect.

Relative Dose Intensity: Improving Cancer Treatment and Outcomes

PURPOSE/OBJECTIVES

To determine the incidence of and reasons for chemotherapy dose delays or reductions.

DESIGN

A performance improvement initiative formed the basis for a prospective nursing research study.

SETTING

A single institution in western Pennsylvania.

SAMPLE

204 patients scheduled for nonmyeloablative chemo-therapy.

METHODS

Data collection forms were completed by RNs and evaluated by an interdisciplinary team.

MAIN RESEARCH VARIABLES

Rates of nonadherence to chemotherapy schedule or dosing and associated reasons.

FINDINGS

The performance improvement initiative revealed evidence of nonadherence to chemotherapy schedule or dosing when patient-requested cancellations and physician-ordered dose delays and reductions were left unchallenged and medical and nursing staffs had limited knowledge of or interest in relative dose intensity. The ensuing nursing research study found that less than 51% and 78% of patients adhered to their schedule and dosage, respectively. Nonadherence primarily was attributed to canceled visits, suboptimal or nonuse of hematopoietic growth factors, and routine dose reductions. Subsequent educational initiatives targeting the interdisciplinary team and patients and their families focused on the importance of keeping scheduled visits and preventing versus managing pancytopenia. Adopting a telephone referral procedure and distributing a patient education sheet reduced patient cancellations by 50%. Various reasons for dose delays and reductions have surfaced, many of which are modifiable with educational efforts.

CONCLUSIONS

A knowledge deficit was found among patients and healthcare providers regarding the importance of adhering to chemo-therapy orders.

IMPLICATIONS FOR NURSING

Evaluating patterns of chemotherapy administration and educating patients, nurses, and physicians will have an impact on relative dose intensity, potentially improving treatment outcomes.

Clinical application of oxaliplatin in epithelial ovarian cancer

Platinum remains the most active drug class in ovarian cancer treatment; however, new single-agent and combination therapies are needed to improve the clinical outcome of ovarian cancer therapies. Oxaliplatin, a third-generation platinum derivative, has shown effective antitumor activity and a favorable toxicity profile in epithelial ovarian cancer. Preclinical evidence of the synergistic cytotoxic effect of oxaliplatin in combination with several other chemotherapeutic agents and clinical evidence of the absence of any dose-limiting hematologic toxicity associated with this agent have made oxaliplatin an attractive compound for combination agent therapy. This article reviews the current status of the clinical application of oxaliplatin alone and in a combination regimen in epithelial ovarian cancer treatment.

The development of platinum compounds and their possible combination

Cisplatin plays a central role in cancer chemotherapy in spite of its toxicity. To circumvent this toxicity and to enhance its therapeutic index a lot of preclinical and clinical studies have been conducted and several thousand analogues have been synthesized. Much more analysis remains to be done, but nowadays, the absence of any definitive, biologically interpretable molecular predictor of activity is consistent with the idea that platinum compounds have multiple intracellular targets and that cells can have multiple mechanisms of resistance. This review analyses a part of these platinum compounds analyzed to date, their mechanism of action, resistance and the future trends in this sector.

Irinotecan, oxaliplatin and raltitrexed for the treatment of advanced colorectal cancer

Out of every 17-18 individuals in the US, one develops colorectal cancer (CRC) in their lifetime. Of individuals diagnosed with CRC, > 50% present or develop metastatic disease, which, if untreated, is associated with 6-9 months median survival. Although surgical resection is the primary treatment modality for CRC, chemotherapy is the mainstay of treatment for metastatic or unresectable disease. For nearly three decades, 5-fluorouracil (5-FU) has been the chemotherapy of choice for treatment of CRC. However, the response rates to single 5-FU therapy have been suboptimal with an objective tumour response of 10-20%. Attempts have been made to improve the efficacy of 5-FU by either schedule alteration (protracted infusion versus intravenous push) or biochemical modulation with leucovorin (LV). Continuous infusion induced more tumour regression and prolonged the time-to-disease progression with some significant impact on survival (11.3 versus 12.1 months; p < 0.04). 5-FU/LV resulted in a significant increase in overall response rates and in the prolongation of disease-free survival in the adjuvant setting, although severe toxicities represent a major clinical problem. The last 10 years have seen the addition of several new agents such as irinotecan, oxaliplatin, raltitrexed, bevacizumab and cetuximab. The prognosis has significantly improved with the addition of these agents, with median survivals now > 20 months. This review paper focuses on irinotecan, oxaliplatin and raltitrexed when used alone and in combination.

Monte Carlo Simulation of Cisplatin Molecule in Aqueous Solution

The Lennard-Jones (12-6) parameters were obtained for all atoms of cisplatin molecule using the ab initio quantum mechanical potential energy surface for the water-cisplatin interaction as reference data. The parameters found were (epsilon/kcal.mol(-1) and sigma/angstroms) 1.0550, 3.6590 (Pt); 0.0381, 4.6272 (Cl); 0.0455, 3.3783 (N); and 0.0185, 0.0936 (H) and provided very good results for the description of the aqueous solution of cisplatin through Monte Carlo simulation. From statistical analysis of solute-solvent interactions, we observed that the NH3 groups are involved in 53% of the calculated hydrogen bonds with a significant contribution from chlorides (41%) and only 6% involving the Pt center. This is in agreement with the expected behavior for such molecules. Two hydration shells with 22 and 81 water molecules, respectively, centered around 4.6 and 7.3 angstroms were found from the center of mass pair correlation function analysis. The cisplatin atomic Lennard-Jones parameters are reported for the first time, and they might be useful for studying the structure, properties, and processes of cisplatin-like molecules in aqueous solution, including explicitly the solvent effect.

EXAFS and IR Structural Study of Platinum-Based Anticancer Drugs' Degradation by Diethyl Dithiocarbamate

Platinum compounds constitute a discrete class of DNA-damaging anticancer drug agents, including cisplatin, carboplatin, and oxaliplatin. The toxicity of such drugs raises the problem of waste detoxification. Diethyl dithiocarbamate (DDTC) is recommended by the World Heath Organization (WHO) for the destruction of cisplatin, but the degradation product has not been structurally characterized. This paper deals with the extended X-ray absorption fine structure (EXAFS) and IR structural study of the reaction products of DDTC with cisplatin, carboplatin, and oxaliplatin. Cisplatin and carboplatin give the same reaction product: Pt(DDTC)2. In the case of oxaliplatin, we observed the formation of [(diaminocyclohexane)(DDTC)Pt(II)]. In all cases, the replacement of labile ligands by strong ligands should lead to inactive compounds. Our results suggest that the WHO inactivation protocol might be extended to carboplatin and oxaliplatin. Nevertheless, this should be validated by toxicity tests of the degradation products.

Safety profile of platinum-based chemotherapy in the treatment of advanced non-small cell lung cancer in elderly patients

Non-small cell lung cancer (NSCLC) may be considered typical of advanced age. More than 50% of NSCLC patients are diagnosed at > 65 years of age and approximately one-third of all patients are > 70 years of age. Elderly patients tolerate chemotherapy poorly compared with their younger counterpart because of the progressive reduction of organ function and comorbidities related to age. For this reason, these patients are often not considered eligible for aggressive platinum-based chemotherapy, the standard medical treatment for advanced NSCLC. In clinical practice, single-agent chemotherapy should remain the standard treatment. Feasibility of platinum-based chemotherapy remains an open issue and has to be proven prospectively. Moreover, a multidimensional geriatric assessment for individualised treatment choice in NSCLC elderly patients is mandatory. This review focuses on the currently-available evidences for the treatment of elderly patients affected by advanced NSCLC with regards to the role and safety of platinum-based chemotherapy.

In vitro toxicological evaluation of a dinuclear platinum(II) complex with acetate ligands

In the present study the toxicological potential of a tumor-inhibiting dinuclear platinum(II) complex (bis(acetato)diammine-bis-micro-acetato diplatinum(II) dihydrate (BAP)) was evaluated, utilizing in vitro models of nephrotoxicity, myelosuppression and neurotoxicity. Regarding the discrepancies between the hallmark toxicity of the clinically utilized platinum drugs, we used three distinct referent compounds as follows cisplatin for the assessment of in vitro nephrotoxicity, carboplatin in case of cultured bone marrow cells and oxaliplatin for the determination of the in vitro neurotoxicty, respectively. The results obtained indicate that the investigated dinuclear complex is endowed by a lower potential to induce detrimental effects upon these typically susceptible platinum toxicity cellular populations as compared to the corresponding referent drugs. These findings, together with the previously encountered profound cytotoxic efficiency of this dinuclear platinum(II) complex against human tumor cell lines, recall for a further detailed evaluation of BAP as potential antineoplastic agent.

Characterization of Intact Hemoglobin and Oxaliplatin Interaction by Nanoelectrospray Ionization Tandem Mass Spectrometry

Background: Mass spectrometric (MS) detection of intact hemoglobin (Hb) adducts presents considerable analytical challenges because of the noncovalent association of the 4 subunits of Hb, and MS characterization of the interaction of intact Hb with platinum drugs has not been reported. We developed a technique for detecting intact Hb and its drug adduct and studied the interactions between intact Hb and oxaliplatin.

Methods: We incubated a series of mixtures of Hb and oxaliplatin at 37 °C for 24 h or 5 days to investigate adduct formation. Blood samples from colorectal cancer patients undergoing oxaliplatin treatment were analyzed for novel adducts of intact Hb–oxaliplatin, which were characterized with nanoelectrospray ionization quadrupole time-of-flight MS.

Results: Two intact Hb adducts, one with the whole oxaliplatin molecule and the other with oxaliplatin losing the oxalate ligand, were identified. Analysis of erythrocytes from the cancer patients provided direct evidence that oxaliplatin accumulated as Hb adducts in erythrocytes. A higher fraction (∼70%) of Hb was bound to oxaliplatin in erythrocytes from a patient who could not tolerate oxaliplatin treatment than in erythrocytes from another patient who benefited from this treatment.

Conclusions: The nanoelectrospray tandem MS technique enabled determination of the intact Hb tetramer and its association with oxaliplatin. Hb–oxaliplatin adducts in erythrocytes may serve as a clinical biomarker for toxic response and treatment efficacy.

Relationship between cisplatin or nedaplatin-induced nephrotoxicity and renal accumulation

Nedaplatin is known to exhibit antitumor activity similar to that of cisplatin. However, concerning side effects, nedaplatin causes renal toxicity less frequently than cisplatin. In this study, we compared the incidence of renal toxicity between cisplatin and nedaplatin by investigating the difference in kidney tissue accumulation. Kidney tissue accumulation of cisplatin administered at 3.75 mg/kg was similar to that of nedaplatin administered at 24 mg/kg. At these doses, the plasma creatinine level and urinary excretion of glucose and N-acetyl-beta-D-glucosaminidase (NAG) similarly increased. There was a correlation between kidney accumulation of cisplatin and nedaplatin and the increases in plasma creatinine level and urinary excretion of NAG. Therefore, our results suggest that nedaplatin less frequently causes renal toxicity in comparison to cisplatin due to lower kidney accumulation.