Pharmacologic effects of cisplatin microspheres on peritoneal carcinomatosis in rodents

Novel electrospun fibers as carriers for delivering a biocompatible Sm(iii) nanodrug for cancer therapy: fabrication, characterization, cytotoxicity and toxicity

The current study represents the successful fabrication and characterization of a Sm(iii) nano complex based on 2-cyano-N'-((4-oxo-4H-chromen-3-yl)methylene)acetohydrazide (CCMA). The fibrous Sm(iii) nanocomplex has been fabricated by the electrospinning technique. SEM analysis of the electrospun fibers has revealed that the fibers have a uniform structure and smooth surface without observing Sm(iii) nanocomplex crystals, i.e. the Sm(iii) nanocomplex has been well incorporated into the fibers. In vitro antitumor activity against two carcinogenic cell lines (HepG-2 and E.A.C.) as well as in vivo toxicity of pure Sm(iii) nanocomplex and its electrospun fibers have been detected. The biological results have shown that there is a significant antitumor activity with low toxicity of the pure Sm(iii) nanocomplex and its electrospun fibers with respect to different standard antitumor drugs. Also, the electrospun fibers recorded higher cytotoxicity (IC₅₀ = 0.1 μM (Hep-G); 0.09 μM (E.A.C)) and lower toxicity (LD₅₀ = 350 mg kg^-1) than the pure ones. The in vitro release rate of the Sm(iii) nanocomplex from electrospun fibers has also been detected. The results have shown that the burst releasing of the Sm(iii) nanocomplex is about 22% after 1 h at the beginning, then a cumulative release increased gradually over the following hours. All results demonstrate the potential use of the Sm(iii) nanocomplex as a potent antitumor drug and its electrospun fibers as superior drug carriers for the treatment of tumors.

Double-Emulsion Copolyester Microcapsules for Sustained Intraperitoneal Release of Carboplatin

Despite on-going medical advances, ovarian cancer survival rates have stagnated. In order to improve IP delivery of platinum-based antineoplastics, we aimed to develop a sustained drug delivery system for carboplatin (CPt). Toward this aim, we pursued a double emulsion process for obtaining CPt-loaded microcapsules composed of poly(ethylene terephthalate-ethylene dilinoleate) (PET-DLA) copolymer. We were able to obtain PET-DLA microspheres in the targeted size range of 10–25 µm (median: 18.5 µm), to reduce intraperitoneal clearance by phagocytosis and lymphoid transit. Empty microspheres showed the lack of toxicity in vitro. The double emulsion process yielded 2.5% w/w CPt loading and obtained microcapsules exhibited sustained (>20 day) zero-order release. The encapsulated CPt was confirmed to be bioavailable, as the microcapsules demonstrated efficacy against human ovarian adenocarcinoma (SK-OV-3) cells in vitro. Following intraperitoneal injection in mice, we did not observe adhesions, only mild, clinically-insignificant, local inflammatory response. Tissue platinum levels, monitored over 14 days using atomic absorption spectroscopy, revealed low burst and reduced systemic uptake (plasma, kidney), as compared to neat carboplatin injection. Overall, the results demonstrate the potential of the developed microencapsulation system for long-term intraperitoneal sustained release of carboplatin for the treatment of ovarian cancer.

Adenoviral-mediated gene transduction of the hepatocyte growth factor (HGF) antagonist, NK4, suppresses peritoneal metastases of gastric cancer in nude mice

The competitive inhibitory effects of NK4 (a specific hepatocyte growth factor (HGF)-antagonist) on the interaction between HGF and the c-Met/HGF receptor has been shown in HGF-mediated invasion of some distinct types of human cancer cells. Furthermore, NK4 has inhibitory effects on the angiogenic pathways driven by basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), as well as by HGF. In this study, to evaluate the therapeutic efficacy of adenoviral-mediated NK4 gene treatment, we employed animal models of peritoneal metastasis using two gastric cancer cell lines, the strongly c-Met expressing MKN45 cell line and the weakly c-Met-expressing cell line, TMK1. In both models, the total number and weight of peritoneal tumours per mouse and ascites treated early with AxCANK4 (administered 3 times 2, 7 and 12 days after the tumour inoculation) were significantly reduced compared with those treated with phosphate-buffered solution (PBS) and AxCALacZ (P < 0.05). In Factor-VIII-related-antigen-stained sections from peritoneal metastatic tumours, the inhibition of intratumour vessels was observed in tissues from tumours of MKN45 and TMK1 treated with AxCANK4. We also compared the therapeutic effect of early AxCANK4 treatment with that of late treatment (at 7, 12 and 17 days). Peritoneal metastases and ascites treated late with AxCANK4 showed less of an improvement than those treated early with AxCANK4 in both models. In addition, the inhibitory effect of cisplatin (CDDP) on peritoneal metastasis was significantly enhanced by AxCANK4, suggesting that the combination of intraperitoneal (i.p.) chemotherapy with NK4 gene therapy might be effective, even in cases of advanced peritoneal metastasis from gastric cancer. To conclude, these results show clearly that NK4 gene therapy inhibits peritoneal metastases from gastric cancer, regardless of the level of c-Met/HGF receptor expression in the tumour cells, and especially in the early stages of peritoneal metastasis.

Intracellular targeting therapy of cisplatin-encapsulated transferrin-polyethylene glycol liposome on peritoneal dissemination of gastric cancer

Peritoneal dissemination in gastric cancer is a common fatal clinical condition with few effective therapies available. We studied the therapeutic effect of a tumor-targeting drug delivery system that uses cisplatin-encapsulated and Tf-conjugated PEG liposomes (Tf-PEG liposomes) in nude mice with peritoneal dissemination of human gastric cancer cells. Small unilamellar Tf-PEG, PEG or DSPC/CH liposomes (bare liposomes) encapsulating cisplatin were prepared by reverse-phase evaporation followed by extrusion. Electron microscopic studies revealed that Tf-PEG liposomes were internalized into tumor cells by receptor-mediated endocytosis. To examine the biodistribution of each liposome and cisplatin level, nude mice were inoculated i.p. with 10(7) MKN45P human gastric tumor cells. On the fourth day after tumor inoculation, (3)H-CHE-labeled and cisplatin-encapsulated Tf-PEG, PEG or bare liposome were inoculated i.p. The Tf-PEG liposome-administered group maintained high liposome and cisplatin levels in ascites and showed a prolonged residence time in the peripheral circulation. Uptake of Tf-PEG liposomes into the liver and spleen was significantly lower than that of bare liposomes. Uptake of Tf-PEG liposomes in disseminated tumor cells of ascites and the greater omentum was significantly higher than that of PEG or bare liposomes and a significant increase in cisplatin levels was observed in these tumor cells. Mice receiving Tf-PEG liposomes 1 and 4 days after the day of tumor inoculation showed significantly higher survival rates compared with those receiving PEG liposomes without Tf, bare liposomes or free cisplatin solution. These results suggest that cisplatin-encapsulated Tf-PEG liposomes may be useful as a new intracellular targeting carrier for treatment of gastric cancer with peritoneal dissemination.

Relation between dissolution profiles and toxicity of cisplatin-loaded microspheres

The aim of this study is to evaluate and compare the dissolution profiles of cisplatin-loaded microspheres (CDDP-MS) in vitro and in vivo, and to determine the relationship between the dissolution profiles in vitro and systemic toxicity. For this purpose, three types of CDDP-MS that release the CDDP for 1, 2 and 5 weeks without a large amount of initial release in phosphate buffered saline (pH 7.4) were prepared. The dissolution profiles of these formulations in vivo were well correlated with in vitro studies, and resulted in well-controlled plasma platinum concentration. The systemic toxicity of the CDDP-MS and CDDP dissolved in saline (CDDP-SOL) were assessed by intraperitoneal administration in mice. The maximal tolerable dose (MTD) of CDDP-SOL was 13.4 mg/kg, whereas the CDDP-MS of 1, 2 and 5-week types were 34.6, 44.2, 62.6 mg/kg, respectively. The MTD of CDDP increased proportionally when 50% of CDDP had been released from MS in vitro (MTD (mg/kg)=5.22 x T(50(day)) + 13.2, R(2)=0.9935). We demonstrate that the systemic toxicity of CDDP-MS can be predicted by evaluation of the dissolution rate in vitro since in vivo dissolution was correlated with the in vitro.

Effects of lipo prostaglandin E1 on distribution of cis-diamminedichloroplatinum in lung metastasis derived from Dunn osteosarcoma cell-inoculated mouse foot-pad

This study was designed to determine the effect of lipid microspheres containing prostaglandin E1 (lipo PGE1) on cis-diamminedichloroplatinum (CDDP) accumulation in primary and lung metastatic lesions. Sixty mice were divided into four groups, depending on whether or not an intra-foot-pad injection of Dunn osteosarcoma cells had been administered and on whether or not an intraperitoneal injection of lipo PGE1 had been administered. CDDP was injected intraperitoneally into all the mice 6 weeks after the inoculation. Tumor colonies of spontaneous metastases in the left lung were found in 21 out of 30 tumor-inoculated mice at autopsy. Tissue platinum concentrations in the lungs with metastatic colonies and in the foot-pad tumors were significantly higher in the lipo PGE1-administered mice than in those without treatment. Terminal deoxytransferase-mediated dUTP nick end labeling (TUNEL) assay showed marked localization of dying cells in the lung metastatic lesions of the lipo PGE1-administered mice. The results of this study showed that pretreatment with lipo PGE1 may augment the antitumor effects of CDDP at the tumor site.

Antitumor effect of cisplatin incorporated into polylactic acid microcapsules

Cisplatin containing microcapsules (CDDP-MC) were prepared by encapsulating cisplatin suspended in a dispersing agent in a copolymer (lactic acid) matrix using an in water drying method. Cisplatin release from the microcapsules was controlled by the addition of albumin. The CDDP-MC were relatively stable in storage, and there was only minimal initial release of the cisplatin from the microcapsules. The antitumor effects of this sustained release dosage form of cisplatin were evaluated in vitro and in vivo in mice. Mice were given an intraperitoneal (i.p.) injection of CDDP-MC 24 h after inoculation with tumor cells. The CDDP-MC were effective against Ehrlich ascites tumors and showed reduced acute toxicity compared with standard cisplatin solution. Due to the small initial release of the cisplatin from the microcapsules, however, the antitumor effect of the CDDP-MC was weaker than that of cisplatin solution. Conventional sustained release preparations have been reported to have large particle sizes and demonstrate large releases of cisplatin from microcapsules. They have been considered more effective than cisplatin solution because of the large initial release of cisplatin from the microcapsules and the maintenance of drug levels. The antitumor effect of our slow-release formulation of cisplatin was evaluated by administration of CDDP-MC 1, 4, and 7 days before i.p. implantation of tumor cells. The survival time of the tumor-bearing mice was prolonged in the CDDP-MC group, but not in the group treated with cisplatin solution. By using this modified formulation of cisplatin, the toxicity of the drug can be reduced, and effective concentrations of the drug can be maintained locally for prolonged periods of time.

Evaluation of mitoxantrone-loaded albumin microspheres following intraperitoneal administration to rats

Mitoxantrone has demonstrated therapeutic efficacy in the regional treatment of intraperitoneal malignancies. However, severe local toxicity was dose limiting. Consequently, a new injectable sustained delivery formulation of mitoxantrone has been developed: the drug was incorporated (8.2 w/w%) in highly hydrophilic albumin microspheres. In vitro drug release profile was modified by matrix crosslinking extent. The extractable amount of residual crosslinking agent (glutaraldehyde) in the microspheres was lower than 6 ppm. Mitoxantrone concentration in peritoneal fluid and plasma was determined up to 72 h after intraperitoneal administration of 30, 60 and 120 mg mitoxantrone per m2 body surface area as solution and in the form of a dispersion containing mitoxantrone-loaded microspheres to rats. Data analysis revealed sustained release of mitoxantrone from microspheres into peritoneal fluid in all dosage groups. The initial high drug levels in peritoneal fluid and plasma observed after application of mitoxantrone in the solution form were prevented by administration of the drug incorporated in microspheres. However, tumoricidal drug levels in peritoneal fluid were maintained over a comparable time span. In addition, preliminary toxicity data suggest a superior local tolerability of mitoxantrone-loaded microspheres. The dose of intraperitoneally administered mitoxantrone might be increased from 30 to 60 mg per m2 body surface area using the slow release formulation. In conclusion, the described microsphere drug delivery system for mitoxantrone might overcome dose-limiting drug toxicity.

Design and testing of a new cisplatin form using a base material by combining poly-D,L-lactic acid and polyethylene glycol acid against peritoneal metastasis

Microspheres containing cisplatin (CDDP) embedded in poly-d,l-lactic acid (PLA) and polyethylene glycol acid (CDDP-PPMS) were developed to improve treatment of malignant effusions. In vitro studies demonstrated that CDDP was released continuously for more than 4 weeks from CDDP-PPMS without initial burst. CDDP-PPMS was compared with CDDP aqueous solution (CDDP-SOL) by i.p. administration in rats for 1) tissue distribution, 2) toxicity and 3) therapeutic effects against Yoshida sarcoma. We found that the CDDP concentration in the omentum was maintained at a higher level than in the CDDP-SOL group, while the particles of CDDP-PPMS were observed in the stomata of the omentum by electron microscopy. Concentrations of CDDP in the lung, liver, kidney and blood were lower in the CDDP-PPMS group than in the CDDP-SOL group. All rats given CDDP-PPMS containing < or = 28 mg/kg were alive, whereas in the CDDP-SOL group, all rats given > or = 16 mg/kg died from side effects. The LD50 of CDDP-PPMS and CDDP-SOL were 32.8 and 14.8 mg/kg, respectively. The survival of rats with peritoneal metastasis was better in the CDDP-PPMS group than in the CDDP-SOL group.

Pharmacological effects of 5-fluorouracil microspheres on peritoneal carcinomatosis in animals

A new delivery formulation (5FU-MS) of 5-fluorouracil (5FU), 5FU incorporated in microspheres composed of poly(glycolide-co-lactide) matrix, has been developed for the treatment of peritoneal carcinomatosis, and is designed to slowly release the incorporated 5FU for 3 weeks. Intraperitoneal 5FU-MS distributed higher concentrations of 5FU to the intraperitoneal tissues, such as the omentum and the mesentery, for a longer period with lower blood plasma concentrations than did the aqueous 5FU solution in rats. In experiments using mice, the lethal toxicity, determined by the probit method, in 5FU-MS was reduced to less than half that in aqueous 5FU solution. We evaluated the therapeutic effects on peritoneal carcinomatosis induced by the intraperitoneal inoculation of B-16 PC melanoma cells. The therapeutic effects of 5FU-MS were enhanced when compared with both the equivalent doses and same toxicity doses of the aqueous 5FU solution.

Improvement of intraperitoneal chemotherapy for rat ovarian cancer using cisplatin-containing microspheres

Microspheres consisting of L-lactic acid and glycolic acid copolymer containing cisplatin (CDDP-PLGA) were developed to improve the delivery of cisplatin. We evaluated the effects of intraperitoneal administration of cisplatin prepared as CDDP-PLGA in rats with ovarian cancer. The toxicity, platinum distribution, and therapeutic effects of CDDP-PLGA were evaluated as compared with those in the case of cisplatin aqueous solution. The LD50 of CDDP-PLGA was almost four-fold higher than that of cisplatin aqueous solution. CDDP-PLGA released cisplatin slowly and achieved a higher concentration in the peritoneal cavity and in peritoneal tumors for prolonged periods, while the tissue concentration of cisplatin was reduced elsewhere in the body, as compared with the case of cisplatin aqueous solution. The survival of rats with peritoneal carcinomatosis was increased by this delivery system relative to cisplatin aqueous solution. CDDP-PLGA thus allows a higher dose to be given without increasing systemic toxicity, enhancing the therapeutic effect of cisplatin.

Inhibition of gastric cancer cell proliferation by antisense oligonucleotides targeting the messenger RNA encoding proliferating cell nuclear antigen

Proliferating cell nuclear antigen (PCNA) is a nuclear protein that regulates DNA synthesis by DNA polymerase delta, and is essential for DNA replication. PCNA expression level is related to the malignancy of gastric cancer cells. Seven different gastric cancer cell lines and two kinds of control cell lines were treated with antisense oligonucleotides complementary to the messenger RNA of PCNA. Treatment of each gastric cancer cell line with antisense oligonucleotides at concentration of 10-40 microM inhibited the cell growth, colony formation and PCNA protein production in a dose-dependent manner, but only affected normal cells slightly. A random sequence oligomer showed no effect. These results show that PCNA is essential for gastric cancer cell proliferation and that the use of synthetic oligonucleotides is an effective way of producing antisense-mediated changes in the behaviour of human gastric cancers.

In vivo activity of bleomycin incorporated with biodegradable poly-d,l-lactic acid and implanted in the mediastinum of dogs

The possible usefulness of bleomycin incorporated with biodegradable poly-d, l-lactic acid (BLM-PLA) for targeting chemotherapy for esophageal cancer was studied in vivo. Local levels of BLM after administration were compared with those after injection of BLM-SOL, an aqueous solution of BLM. BLM-PLA or BLM-SOL was administered into the upper mediastinum under a right thoracotomy in 36 mongrel dogs. On days 10, 20, and 30 after administration, connective tissues, lymph nodes, lung, liver, kidney, and spleen were removed, and BLM activity was measured. High activity of BLM was detected for 30 days after BLM-PLA administration in both the connective tissues and the lymph nodes, compared with BLM-SOL administration. BLM activity was low in the other organs after BLM-PLA administration. BLM in the blood was significantly lower after administration of BLM-PLA than BLM-SOL. The results indicate that BLM-PLA may become a useful tool in targeting chemotherapy for esophageal cancer.