Cytotoxic drug sensitivity of Epstein-Barr virus transformed lymphoblastoid B-cells.

BACKGROUND: Epstein-Barr virus (EBV) is the causative agent of immunosuppression associated lymphoproliferations such as post-transplant lymphoproliferative disorder (PTLD), AIDS related immunoblastic lymphomas (ARL) and immunoblastic lymphomas in X-linked lymphoproliferative syndrome (XLP). The reported overall mortality for PTLD often exceeds 50%. Reducing the immunosuppression in recipients of solid organ transplants (SOT) or using highly active antiretroviral therapy in AIDS patients leads to complete remission in 23-50% of the PTLD/ARL cases but will not suffice for recipients of bone marrow grafts. An additional therapeutic alternative is the treatment with anti-CD20 antibodies (Rituximab) or EBV-specific cytotoxic T-cells. Chemotherapy is used for the non-responding cases only as the second or third line of treatment. The most frequently used chemotherapy regimens originate from the non-Hodgkin lymphoma protocols and there are no cytotoxic drugs that have been specifically selected against EBV induced lymphoproliferative disorders. METHODS: As lymphoblastoid cell lines (LCLs) are well established in vitro models for PTLD, we have assessed 17 LCLs for cytotoxic drug sensitivity. After three days of incubation, live and dead cells were differentially stained using fluorescent dyes. The precise numbers of live and dead cells were determined using a custom designed automated laser confocal fluorescent microscope. RESULTS: Independently of their origin, LCLs showed very similar drug sensitivity patterns against 29 frequently used cytostatic drugs. LCLs were highly sensitive for vincristine, methotrexate, epirubicin and paclitaxel. CONCLUSION: Our data shows that the inclusion of epirubicin and paclitaxel into chemotherapy protocols against PTLD may be justified

Cisplatin and Oxaliplatin Toxicity: Importance of Cochlear Kinetics as a Determinant for Ototoxicity

Background Cisplatin is a commonly used platinum anti-cancer drug. Regrettably cisplatin has dose-limiting ototoxic side effects, e.g. the drug can induce an irreversible hearing loss. The ototoxic mechanisms of cisplatin have not been elucidated in the human ear and no clinically useful oto-protectors are yet available. Cisplatin is a necessary part of many treatment regimes. Its beneficial therapeutic effects might be reduced if cisplatin was excluded from the treatment in order to protect the hearing function. In this work the ototoxic effects of cisplatin are studied with the aim to better understand the mechanisms behind the irreversible hearing loss induced by this drug. Oxaliplatin is a second generation platinum-derivative anti-cancer drug, free from ototoxic side effects in clinical practice. The effects of oxaliplatin on the inner ear have been studied in this work and the results are compared with cisplatin treatment. The two drugs differ regarding both anti-cancer effects and side effects, which could be attributed to differences in pharmacokinetic factors, cellular uptake and apoptotic mechanisms. The thioredoxin redox system with the enzyme thioredoxin reductase (TrxR) was studied in cochleae due to a suggested DNA-independent apoptotic mechanism of the hair cells. The cochlear pharmacokinetics of cisplatin was assessed and the transport protein organic cation transporter 2 (OCT2) was studied in relation to the ototoxic effect of cisplatin. Material and methods Cultured human colon carcinoma cells and cell cultures of rat organ of Corti were used for apoptosis studies in vitro following exposure to cisplatin and oxaliplatin. Cisplatin and oxaliplatin were administered i.v. to guinea pigs, followed by in vivo sampling of blood, cerebrospinal fluid (CSF) and scala tympani (ST) perilymph. Liquid chromatography with post-column derivatization was used to determine the concentration of parent drug in the samples. Electrophysiological hearing thresholds and the loss of hair cells were assessed to evaluate their ototoxic effects. Phenformin, a potential blocker of OCT2 was administered and the ototoxic side effect of cisplatin was evaluated. For immunohistochemical studies, cochlea from rat, guinea pig and pig were used, where TrxR and OCT2 were evaluated in the cochlea. TrxR-assays were used to measure the TrxR activity in cochlear tissue, both in vivo and in vitro. Results The results from the in vitro studies showed that addition of either cisplatin or oxaliplatin to the culture medium in organ of Corti cell cultures caused a similar amount of outer hair cell loss and inhibition of TrxR activity. Cisplatin exposure to cultured human colon carcinoma cells also reduced the activity of TrxR. The results from the in vivo studies showed that a considerable concentration of cisplatin was present in ST perilymph as compared with weak concentrations of oxaliplatin after high dose oxaliplatin i.v. Ten minutes after cisplatin administration, its concentration in ST perilymph was 4-fold higher in the basal turn of the cochlea as compared to the apex. Cisplatin could be analysed in ST perilymph for up to 120 min. Phenformin i.v. did not reduce the ototoxic side-effect of cisplatin. Positive immunoreactivity to TrxR was evident in both hair cells and spiral ganglion cells. Futhermore, OCT2 was expressed in the supporting cells of organ of Corti and in the spiral ganglion cells. Conclusion The transport of cisplatin to the vulnerable cells of hearing seems to be of major importance for the ototoxic effects. An early high concentration of cisplatin in the base of the cochlea and delayed elimination of cisplatin from ST perilymph may be related to the cisplatin-induced loss of outer hair cells in the basal turn of the cochlea. Cisplatin and oxaliplatin both cause similar ototoxic effects when the organ of Corti is directly exposed in vitro. The thioredoxin redox system with the TrxR enzyme may well play a critical role in cisplatininduced ototoxicity. The presence of OCT2 in the supporting cells indicates that this transport protein is primarily not involved in the uptake of cisplatin from the systemic circulation but rather from the deeper compartments of the cochlea. The knowledge elicited in this work will hopefully suggest objectives for further studies in order to develop oto-protective treatments to preserve the hearing of cisplatin treated patients

Phase I dose escalation and pharmacokinetic study of pluronic polymer-bound doxorubicin (SP1049C) in patients with advanced cancer

SP1049C is a novel anticancer agent containing doxorubicin and two nonionic pluronic block copolymers. In preclinical studies, SP1049C demonstrated increased efficacy compared to doxorubicin. The objectives of this first phase I study were to determine the toxicity profile, dose-limiting toxicity, maximum tolerated dose and pharmacokinetic profile of SP1049C, and to document any antitumour activity. The starting dose was 5 mg m−2 (doxorubicin content) as an intravenous infusion once every 3 weeks for up to six cycles. A total of 26 patients received 78 courses at seven dose levels. The dose-limiting toxicity was myelosuppression and DLT was reached at 90 mg m−2. The maximum tolerated dose was 70 mg m−2 and is recommended for future trials. The pharmacokinetic profile of SP1049C showed a slower clearance than has been reported for conventional doxorubicin. Evidence of antitumour activity was seen in some patients with advanced resistant solid tumours. Phase II trials with this agent are now warranted to further define its antitumour activity and safety profile

Elucidation of the liquid-liquid distribution behavior of ion associates of metal-halogeno complex anions with quaternary ammonium counter cations and its application to separation and analysis

第四級アンモニウムイオンを対イオンとする一価, 二価金属ハロゲノ錯陰イオンのイオン会合抽出挙動を把握し, 分離・分析的応用を図るために, 炭素数及び形状の異なる第四級アンモニウム陽イオンを用いて, 水-各種抽出溶媒 {1,2-ジクロロエタン, クロロホルム (CF), クロロベンゼン (Cl-B), ベンゼン (B), トルエン (T) 及び四塩化炭素 (CTC)} 系での抽出定数を求めた. 得られた抽出定数から次の知見を得た. (1) 配位子の抽出性に及ぼす影響 : 配位子がCl-, Br-, I-と変わるにつれ, この順に抽出性は良くなる. (2) 配位子数の影響 : 配位子数が多くなるに従い, 抽出性も良くなる. (3) 中心金属の影響 : 配位子数が同じ場合には, 抽出性はほぼ中心金属イオンの大きさの順となる. (4) 金属錯陰イオンの電荷の影響 : 一般に二価陰イオンよりも一価陰イオンのほうが抽出されやすい. (5) 対陽イオンのアルキル鎖のメチレン基の寄与 : メチレン基一つ当たり, 大体0.4～0.8の抽出定数 (log K(ex)) の増大となる. (6) 抽出溶媒の影響 : 抽出溶媒の抽出能は次の順となる : CTC<T<B<Cl-B<CF. (7) 金属ハロゲノ錯陰イオンの配位子の違いによる抽出定数の差 (Δlog K(ex)) は溶媒によらず, ほぼ一定である. これらの知見を基に, 金属ハロゲノ錯陰イオンと疎水性陽イオンとのイオン会合抽出を利用する幾つかの金属の分離・定量法を開発した.The distribution behavior of ion associates of both monovalent and divalent metal-halogeno complex anions with various quaternary ammonium cations between the aqueous phase and several organic phases {1,2-dichloroethane, chloroform (CF), chlorobenzene (Cl-B), benzene (B), toluene (T) and carbon tetrachloride (CTC)} was examined, and the extraction constants (log Kex) were determined. The larger is the size of the ligand (Cl-<Br-<I-) and the coordination number, the greater is the ion associability. For the same coordination number, in general, the larger is the size of the metal ion, the greater is the ion associability. In general, the extractability of monovalent metal-halogeno complex anions is larger than that of divalent metal-halogeno complex anions. A linear relationship was obtained between log Kex and the number of carbon atoms in quaternary ammonium ion, and the contribution of a methylene group to the extraction constant (Δlog K(ex)/-CH(2-)) was found to be about 0.4∼0.8. Among the ion associates examined, the order of the extractability of the extracting solvent was generally CTC<T<B<Cl-B<CF. Also, the order of the extractability of the ion associates for dihalogenocuprate (I), tetrahalogenoaurate (III) and tetrahalogenothallate (III) complex ions was as follows, respectively : CuCl(2)-<CuBr(2)-<CuI(2)- ; AuCl(4)-<AuBr(4)- ; TlCl(4)-<TlBr(4)-<TlI(4-). The values of Δlog K(ex) between the complex anions were almost equal, even though the extracting solvents were changed. From these results, several extraction-spectrophotometric methods for the determination of metal based on the formation of an ion associate of metal-halogeno complex anion with hydrophobic cations were developed

Cytotoxic drug sensitivity of Epstein-Barr virus transformed lymphoblastoid B-cells

BACKGROUND: Epstein-Barr virus (EBV) is the causative agent of immunosuppression associated lymphoproliferations such as post-transplant lymphoproliferative disorder (PTLD), AIDS related immunoblastic lymphomas (ARL) and immunoblastic lymphomas in X-linked lymphoproliferative syndrome (XLP). The reported overall mortality for PTLD often exceeds 50%. Reducing the immunosuppression in recipients of solid organ transplants (SOT) or using highly active antiretroviral therapy in AIDS patients leads to complete remission in 23–50% of the PTLD/ARL cases but will not suffice for recipients of bone marrow grafts. An additional therapeutic alternative is the treatment with anti-CD20 antibodies (Rituximab) or EBV-specific cytotoxic T-cells. Chemotherapy is used for the non-responding cases only as the second or third line of treatment. The most frequently used chemotherapy regimens originate from the non-Hodgkin lymphoma protocols and there are no cytotoxic drugs that have been specifically selected against EBV induced lymphoproliferative disorders. METHODS: As lymphoblastoid cell lines (LCLs) are well established in vitro models for PTLD, we have assessed 17 LCLs for cytotoxic drug sensitivity. After three days of incubation, live and dead cells were differentially stained using fluorescent dyes. The precise numbers of live and dead cells were determined using a custom designed automated laser confocal fluorescent microscope. RESULTS: Independently of their origin, LCLs showed very similar drug sensitivity patterns against 29 frequently used cytostatic drugs. LCLs were highly sensitive for vincristine, methotrexate, epirubicin and paclitaxel. CONCLUSION: Our data shows that the inclusion of epirubicin and paclitaxel into chemotherapy protocols against PTLD may be justified

A tumor cord model for Doxorubicin delivery and dose optimization in solid tumors

<p>Abstract</p> <p>Background</p> <p>Doxorubicin is a common anticancer agent used in the treatment of a number of neoplasms, with the lifetime dose limited due to the potential for cardiotoxocity. This has motivated efforts to develop optimal dosage regimes that maximize anti-tumor activity while minimizing cardiac toxicity, which is correlated with peak plasma concentration. Doxorubicin is characterized by poor penetration from tumoral vessels into the tumor mass, due to the highly irregular tumor vasculature. I model the delivery of a soluble drug from the vasculature to a solid tumor using a tumor cord model and examine the penetration of doxorubicin under different dosage regimes and tumor microenvironments.</p> <p>Methods</p> <p>A coupled ODE-PDE model is employed where drug is transported from the vasculature into a tumor cord domain according to the principle of solute transport. Within the tumor cord, extracellular drug diffuses and saturable pharmacokinetics govern uptake and efflux by cancer cells. Cancer cell death is also determined as a function of peak intracellular drug concentration.</p> <p>Results</p> <p>The model predicts that transport to the tumor cord from the vasculature is dominated by diffusive transport of free drug during the initial plasma drug distribution phase. I characterize the effect of all parameters describing the tumor microenvironment on drug delivery, and large intercapillary distance is predicted to be a major barrier to drug delivery. Comparing continuous drug infusion with bolus injection shows that the optimum infusion time depends upon the drug dose, with bolus injection best for low-dose therapy but short infusions better for high doses. Simulations of multiple treatments suggest that additional treatments have similar efficacy in terms of cell mortality, but drug penetration is limited. Moreover, fractionating a single large dose into several smaller doses slightly improves anti-tumor efficacy.</p> <p>Conclusion</p> <p>Drug infusion time has a significant effect on the spatial profile of cell mortality within tumor cord systems. Therefore, extending infusion times (up to 2 hours) and fractionating large doses are two strategies that may preserve or increase anti-tumor activity and reduce cardiotoxicity by decreasing peak plasma concentration. However, even under optimal conditions, doxorubicin may have limited delivery into advanced solid tumors.</p