Sequential chemotherapy in good-prognosis patients with small-cell lung cancer

Nucleic acid therapeutics: concepts for targeted delivery to solid tumors

Solid tumors form a heterogeneous group of diseases, although common features such as hyperproliferation, overexpression of certain growth factor receptors and deregulated vessel formation including leaky vasculature give the opportunity to target macromolecular drug and nucleic acid carriers to tumor tissue. Similar to other macromolecular drugs, nucleic acid carriers have to be designed to enable tumor targeting after systemic injection. Chemical modification of nucleic acids makes them resistant towards enzymatic degradation. Cationic lipids or polycations condense nucleic acids into small, virus-like structures and the surface modification with hydrophilic polymers allows passive accumulation in tumor tissue; tumor cell binding ligands allow cellular targeting. To avoid toxic side effects, biodegradable and biocompatible carriers were designed. The design of thermoresponsive gene carriers allowed their selective tumor accumulation by locoregional hyperthermia. As a therapeutic concept, tumor-specific delivery of antitumoral RNA was realized in an orthotopic brain tumor model. The combination of gene- and radio-therapy enabled selective accumulation of radionuclides in tumors and boosted antitumoral effects. Hence, combining a smart delivery concept for nucleic acids with a suitable therapeutic strategy will allow successful treatment of otherwise incurable malignant diseases.

Synthesis and In vitro activity of ROMP-based polymer nanoparticles

A new type of polymer nanoparticle (PNP) containing a high density of covalently linked doxorubicin, attached via a non-cleavable amine linkage (amine-linked Dox-PNP) was prepared. Together with a previously reported cleavable carbamate-linked Dox-PNP, this new amine-linked Dox-PNP was subsequently evaluated against free doxorubicin for its cytotoxicity and inhibitory effects on SKNSH wild-type and SKrDOX6 doxorubicin-resistant human neuroblastoma cell lines. Analogous cholesterol-containing PNPs (Chol-PNPs) and indomethacin-containing PNPs (IND-PNPs) were also synthesized and used as the non-cytotoxic controls. While neither cell line was affected by Chol-PNPs or IND-PNPs, SKrDOX6 doxorubicin-resistant cells exhibited similar cytotoxic responses to free doxorubicin and both amine- and carbamate-linked Dox-PNPs, suggesting that doxorubicin or the doxorubicin-containing polymer must be the active agent in the latter case. SKNSH wild-type cells also responded to both Dox-PNPs, albeit at a higher apparent concentration than free doxorubicin alone. The growth of SKNSH wild-type cells was significantly inhibited upon incubation with carbamate-linked Dox-PNPs, as with free doxorubicin, over a 7-day period. In comparison to free doxorubicin, carbamate-linked Dox-PNPs produced a longer (72-h) period of initial inhibition in SKrDOX6 doxorubicin-resistant cells.

Pharmacokinetics of doxorubicin and cisplatin used in intraoperative hyperthermic intrathoracic chemotherapy after cytoreductive surgery for malignant pleural mesothelioma and pleural thymoma

Cytoreductive surgery combined with intraoperative hyperthermic intrathoracic chemotherapy (HITHOC) is studied in a phase I study in the treatment of malignant pleural mesothelioma and pleural thymoma. We studied the pharmacokinetics of doxorubicin and cisplatin used during the HITHOC procedure. Furthermore, the penetration characteristics of doxorubicin were examined. Between 1998 and 2001, 24 perfusions were performed with a solution containing doxorubicin and cisplatin for 90 min at 40-41 degrees C. The dose was first based on square meters body surface, whereas in later studies a fixed concentration of the perfusion fluid was used. Samples of blood and perfusion fluid were collected for doxorubicin and cisplatin measurements. The penetration characteristics of doxorubicin in tissue were determined by fluorescence microscopy. The mean AUC(perfusate):AUC(plasma) ratios for doxorubicin and cisplatin (ultrafiltration for plasma) were 99 and 59, respectively. During perfusion the concentration in the perfusate declined essentially according to first-order elimination kinetics for both doxorubicin and cisplatin with half-lives of 74 and 138 min, respectively. At the end of the perfusion, about 35 and 52% of the dose of doxorubicin and cisplatin, respectively, was recovered in the perfusion fluid. One patient developed a nephrotoxicity grade II. No leukopenia or hair loss was seen. Doxorubicin penetrated into the intercostal muscle specimen, albeit that there was considerable variation in distribution throughout the specimen. We conclude that HITHOC with doxorubicin and cisplatin is relatively a safe procedure with the advantage of high intrathoracic cytostatic drug concentrations, while having limited systemic side effects.

Weekly epirubicin plus lonidamine in advanced breast carcinoma

Lonidamine has been demonstrated to potentiate the cytotoxic activity of several antineoplastic drugs, for example anthracyclines. Moreover, epirubicin is considered one of the most active drugs in advanced breast cancer, although optimal dose and schedule remains to be defined. In the present study we have treated 51 patients with advanced breast cancer with a combination of lonidamine (450 mg/day orally from day 1 throughout treatment) and epirubicin (25 mg/m2 i.v.) administered according to a weekly schedule for 24 weeks. Objective responses were observed in 29 out of 51 patients (57%; CR 16%, PR 41%). Liver metastases responded in eight out of 12 evaluable patients (67%). Average response duration was 12.4 months and median overall survival was 23 months (range 1-90+). Toxicity was negligible. The combination of weekly epirubicin and lonidamine is feasible and active in advanced breast cancer patients.

Effects of 4-hydroperoxy ifosfamide in combination with other anticancer agents on human cancer cell lines

Ifosfamide is one of the currently available anticancer agents with a broad spectrum of clinical activity against a variety of tumors. To investigate its optimal combinations, we studied the effect of 4-hydroperoxy ifosfamide (the active form of ifosfamide) in combination with other anticancer agents against two human cancer cell lines, MG-63 (an osteosarcoma cell line) and MOLT-3 cells (a T-cell leukemia cell line). The cells were incubated for 4 days and 3 days, respectively, in the presence of 4-hydroperoxy ifosfamide and the other agent. Cell growth inhibition was determined by MTT assay. The effects of these drug combinations at the concentration producing 50% inhibition (IC50) were analyzed by the isobologram method. 4-Hydroperoxy ifosfamide showed additive effects with bleomycin, cisplatin, cytarabine, doxorubicin, etoposide, 5-fluorouracil, and mitomycin C, while it showed a protective effect with methotrexate in both cell lines. 4-Hydroperoxy ifosfamide showed an additive effect with vincristine in the MG-63 cell line, while it showed a sub-additive effect in the MOLT-3 cell line. No anticancer agents tested showed a supra-additive effect with 4-hydroperoxy ifosfamide. These data suggest that ifosfamide is advantageous for simultaneous administration with a majority of the anticancer agents we studied. Methotrexate is an inappropriate drug for simultaneous administration with ifosfamide.

Comparative open, randomized, cross-over bioequivalence study of two intravenous dexrazoxane formulations (Cardioxane and ICRF-187) in patients with advanced breast cancer, treated with 5-fluorouracil-doxorubicin-cyclophosphamide (FDC)

The purpose of this study was to compare the pharmacokinetic disposition of two intravenous dexrazoxane formulations, and their effects on doxorubicin's kinetics and metabolism. Plasma concentration versus time curves and pharmacokinetic parameters of dexrazoxane given as Cardioxane (dexrazoxane hydrochloride salt) and ICRF-187 reference formulation (dexrazoxane base) were determined and compared. Both formulations were administered as a single intravenous infusion prior to 5-fluorouracil-doxorubicin-cyclophosphamide administration. In addition, the pharmacokinetics of doxorubicin and its metabolites were studied after dexrazoxane administration. A total of 15 patients with advanced breast cancer participated in this open, randomized, cross-over study and 12 patients were evaluable. Plasma concentrations of dexrazoxane, doxorubicin and doxorubicin metabolites were determined by high-performance liquid chromatography in samples obtained in the 72 h after drug administration. No statistically significant differences were found in the tested kinetic parameters when the two products were compared by analysis of variance (ANOVA) on log-transformed data. Cardioxane fulfilled the bioequivalence criteria when compared with ICRF-187 reference formulation for all of the investigated parameters (AUC, t1/2beta, Vdss, Cl(tot), Cl(ren)). The parametric 90% confidence intervals were contained within the bioequivalence interval (0.8-1.25). Pharmacokinetic parameters and metabolism of doxorubicin were not different after the administration of either Cardioxane or ICRF-187 formulation. From the results of this study it can be concluded that the two formulations can be considered bioequivalent with regard to extent of absorption (AUC and Vdss) and elimination (t1/2beta, Cl(tot) and Cl(ren)).

Therapeutic drug monitoring of doxorubicin in paediatric oncology using capillary electrophoresis

A method for the determination of doxorubicin and its main metabolite doxorubicinol in human plasma is described. Two different sample preparation procedures are applied depending on the expected concentration: To monitor the peak plasma levels, 10 microL of plasma are deproteinated with acetonitrile. After centrifugation, the supernatant is directly applied to the capillary by hydrodynamic injection. For the determination of lower amounts of doxorubicin and its main metabolite doxorubicinol 100 microL of plasma is extracted by liquid-/liquid extraction with chloroform. After evaporation of the organic phase, the sample is reconstituted in acetonitrile/water (95/5 v/v) and injected into the capillary by electrokinetic injection. Idarubicin serves as the internal standard. Laser-induced fluorescence detection with an Ar-ion laser emitting at 488 nm and a 520 nm cut-off filter is used for detection. The accuracy of the method was calculated to be 3.0% at higher concentrations and 15.0% at the limit of quantification. Reproducibility data are in accordance to the generally accepted criteria for bioanalytical methods. The limit of quantification is 2 microg/L, enabling us to monitor doxorubicin plasma levels for several days after application. Noninvasive blood sampling (from the fingertip) using heparinized capillaries was found to be a simple and convenient procedure and provides reproducible data. Initial results show high interindividual variability in doxorubicin peak plasma levels.

Doxorubicin and doxorubicinol pharmacokinetics and tissue concentrations following bolus injection and continuous infusion of doxorubicin in the rabbit

Cumulative dose-related, chronic cardiotoxicity is a serious clinical complication of anthracycline therapy. Clinical and animal studies have demonstrated that continuous infusion, compared to bolus injection of doxorubicin, decreases the risk of cardiotoxicity. Continuous infusion of doxorubicin may result in decreased cardiac tissue concentrations of anthracyclines, including the primary metabolite doxorubicinol, which may also be an important contributor to cardiotoxicity. In this study, doxorubicin and doxorubicinol plasma pharmacokinetics and tissue concentrations were compared in New Zealand white rabbits following intravenous administration of doxorubicin (5 mg.kg-1) by bolus and continuous infusion. Blood samples were obtained over a 72-h period after doxorubicin administration to determine plasma doxorubicin and doxorubicinol concentrations. Rabbits were killed 7 days after the completion of doxorubicin administration and tissue concentrations of doxorubicin and doxorubicinol in heart, kidney, liver, and skeletal muscle were measured. In further experiments, rabbits were killed 1 h after bolus injection of doxorubicin and at the completion of a 24-h doxorubicin infusion (anticipated times of maximum heart anthracycline concentrations) to compare cardiac concentrations of doxorubicin and doxorubicinol following both methods of administration. Peak plasma concentrations of doxorubicin (1739 +/- 265 vs 100 +/- 10 ng.ml-1) and doxorubicinol (78 +/- 3 vs 16 +/- 3 ng.ml-1) were significantly higher following bolus than infusion dosing. In addition, elimination half-life of doxorubicinol was increased following infusion. However, other plasma pharmacokinetic parameters for doxorubicin and doxorubicinol, including AUC infinity, were similar following both methods of doxorubicin administration. Peak left ventricular tissue concentrations of doxorubicin (16.92 +/- 0.9 vs 3.59 +/- 0.72 micrograms.g-1 tissue; P < 0.001) and doxorubicinol (0.24 +/- 0.02 vs 0.09 +/- 0.01 micrograms.g-1 tissue; P < 0.01) following bolus injection of doxorubicin were significantly higher than those following infusion administration. Tissue concentrations of parent drug and metabolite in bolus and infusion groups were similar 7 days after dosing. The results suggest that cardioprotection following doxorubicin infusion may be related to attenuation of the peak plasma or cardiac concentrations of doxorubicin and/or doxorubicinol.