New specific therapy targeting cancer cell was reviewed. The history of tumor markers (CEA, AFP) and the development of antibody from conventional polyclonal antibody to monoclonal antibody including chimeric or humanized antibody were introduced. Trials using antibody alone, antibody conjugated with drugs and antibody labelled with radioisotopes were summarized. Receptors on cancer cell membrane could be a good marker of cancer available for the diagnosis and therapy. Finally gene therapy was introduced and it was emphasized that new drug (gene) delivery system will be necessary for the development of practical gene therapy of cancer.

View full abstract

A high-performance size-exclusion chromatography (HPSEC), using TSKgel G3000SW column, for the quantitative analysis of FITC-labeled dextran and pullulan in the biological specimen was developed. FITC-labeled dextrans of various molecular weights (Mw=4, 400∼485, 000) were purchased from Sigma Co., whereas pullulans (Mw=5, 300∼611, 000) were labeled with FITC by the method of de Belder and Granath. These derivatives showed a very low degree of substitution at which the labeling of the parent polysaccharides with FITC did not affect their chromatographic behavior. Linear calibration curves were obtained at amounts down to 5 ng when the derivatives were monitored fluorometrically. The FITC-labeled polysaccharides were susceptible to the enzyme catalyzed hydrolysis. A total peak area of the degraded fractions with smaller molecular weights was identical to that obtained with the parent compound. These results indicate that labeling the polysaccharides with FITC and monitoring fluorometrically by HPSEC is a promising method for the pharmacokinetic investigations on the macromolecular conjugates. The applicability of the method was demonstrated by measuring the hepatic level-time profile and biodegradation of a FITC-labeled dextran following injection to mice.

View full abstract

S-1 is an oral form mixture of tegafur (FT) which produces 5-FU, 5-chloro-2, 4-dihydroxypyridine (CDHP) which inhibits 5-FU degradation and oxonic acid (Oxo) which reduces 5-FU toxicities, in a molar ratio of 1 : 0.4 : 1. Pharmacokinetics of S-1 were studied using tumor-bearing animals. Bioavailahility : AUC_po/AUC_iv ratios of FT, CDHP and 5-FU in rabbits were almost 100% with some individual differences, while that of Oxo was 10% or less. The ratio showed a tendency to be higher in fasting animals than in feeding animals, especially in the case of 5-FU (P<0.05). CDHP and Oxo : In tumor-bearing rabbits and mice, CDHP was absorbed well and distributed at high levels in the GI tract and kidney, and detected at moderate levels in the liver, tumor and plasma. The most part of Oxo remained in the GI tract and it was also detected at a high concentration in the kidney, while at low in the liver, tumor and bone marrow. 5-FU following dose escalation of S-1 : S-1 was administered to tumor-bearing rats at doses of 2, 5, 10, 20 mg/kg. AUCs_0∼24h of 5-FU were observed at the highest in the tumor in any dosing groups, in order of tumor>bone marrow>spleen>kidney>GI tract>liver and plasma. However, it was noticeable that AUC_tumor/AUC_plasma ratio rather decreased as the escalation of S-1 dose. The reason would be that 5-FU increased non-linearly in the plasma and most normal tissues following the dose escalation of S-1. Based on these data, the optimum dosage of S-1 in humans should be established to maximize the anticancer effects and minimize the adverse reactions.

View full abstract

We have developed a novel sustained release formulation, minipellet, which is applicable to various kinds of biologically active proteins. In this study, dosage form design of interferon (IFN) minipellet was investigated. First, in order to select suitable carrier material, matrix type formulations were prepared with natural biodegradable polymers, human serum albumin (HSA), gelatin and atelocollagen, and the release profiles of IFN from these polymers were compared. IFN was released slowly from the sample made of atelocollagen but rapidly from the samples made of HSA and gelatin. The release of IFN from the atelocollagen films, prepared by drying the atelocollagen solution, varied with the atelocollagen concentration before drying. This suggested that IFN release was controlled by the density of atelocollagen matrix. So, in order to obtain the higher matrix density of atelocollagen, we newly designed a cylindical dosage formulation prepared by extrusion and air-drying of an atelocollagen solution with high concentration and named minipellet. IFN was constantly released from minipellet in vitro. Pharmacokinetic studies in mice showed that the serum IFN concentration was maintained for a long time with minipellet. To determin the optimal minipellet composition, IFN minipellets containing different amount of HSA were prepared and IFN release profile from them in dogs was evaluated, The IFN concentration increased gradually after the administration of IFN minipellet containing 30% (w/w) HSA, reached C_max after 24h, and decreased gradually thereafter with a detectable level for 10 days. The IFN minipellet is expected to offer a significant advantage in IFN therapy because the attenuated peak IFN concentrations in serum may reduce the side effects and the sustained release may reduce the frequency of administration.

View full abstract

Malignant glioma responds poorly to chemotherapy presumably mainly because the antitumor drugs can not be delivered in effective concentrations to the tumor site without causing complications, and because the existence of the blood-brain barrier (BBB) restricts the distribution of many antitumor drugs to malignant gliomas. We used thermosensitive liposomes containing CDDP (cis-diamminedichloroplatinum) with localized heating, and the possibilities of this drug delivery system to the brain tumor were discussed. First, this unique and attractive strategy showed remarkable effects against the RSV-induced subcutaneous tumor which was relatively insensitive to various antitumor agents. The authors then investigated the antitumor effect on rat malignant brain tumor. Ten days after tumor inoculation, six groups were formed : control, free CDDP, hyperthermia, free CDDP+hyperthermia, CDDP-liposome, and CDDP-liposome+hyperthermia. Liposomes containing CDDP (CDDP-liposome) or free CDDP were injected via the tail vein. The brain tumor heating was given using a radiofrequency antenna which was designed at our institute. As a result, the rats treated by CDDP-liposome+hyperthermia had the longest survival time, and the tumor CDDP level of this group was the highest when compared to other groups. These findings suggest that the combination of thermosensitive liposome and localized hyperthermia, could (1) bring a direct thermal killing of the tumor cells, plus (2) increase a permeability of the BBB to transport of CDDP, plus (3) target CDDP-liposomes to the tumor site and produce an effective release of liposomal CDDP with greater activity than when free CDDP was injected.

View full abstract

We previously reported that caffeine inhibited adriamycin efflux in Ehrlich ascites carcinoma cells and it would be of value as biochemical modulator of adriamycin. In this study, the transport of adriamycin was investigated, in vitro, as a part of a study to clarify the mechanism of adriamycin efflux inhibition by caffeine, using metabolites of caffeine. The mechanism of the effect of caffeine on adriamycin antitumor activity, in vivo, was also studied.1, 3, 7-Trimethyluric acid did not inhibit adriamycin efflux on tumor cells in vitro, and did not enhance the antitumor activity of adriamycin in vivo. Furthermore, 1, 7-dimethylxanthine, which is the major caffeine metabolite in human, promoted adriamycin efflux. However, theobromine would be of value as biochemical modulator of adriamycin from in vitro and in vivo study. Moreover, when the temperature of incubation was 20°C, the inhibition of adriamycin efflux by caffeine did not observed, It suggest that some enzymes system in the cell will be related to adriamycin efflux. However, since ouabain had no effect on the adriamycin efflux, Na⁺, K⁺-ATPase do not concern with adriamycin efflux. And in medium without glucose, there were no effects of caffeine. It suggested that energy which supply from glucose is needed to adriamycin transport. These results suggest that the effect of caffeine, as biochemical modulator, is not due to metabolite of caffeine. And the transport of adriamycin and effects of caffeine is considered to be related to some enzymes and to some energy consumptions in the cell.

View full abstract

To prevent the emesis associated with anticancer therapy with chemotherapeutic drugs, various investigations have been conducted into transdermal dosage forms containing timiperone, antipsychotics and strong antiemetics. In the present study, we used the water-soluble polymers as a matrix for transdermal dosage forms. Further, we also evaluated the effect of matrix pH on the inhibition action of timiperone on apomorphine-induced stereotyped behavior in an in vivo model in rats, and compared pharmacological activity with these water-soluble matrices to that obtained with a plaster formulation. Inhibition of timiperone on apomorphine-induced stereotyped behavior was used as an index of percutaneous absorption of timiperone. Results showed that pharmacological activity increased with increasing matrix pH. This finding suggests that the percutaneous absorption of timiperone is pH-dependent. At 4 h after the administration of water-soluble polymer matrices, the pharmacological activity of timiperone was closely similar to that at the same time-point after oral administration of the drugs. Further, this activity was maintained for up to about 8 h after administration. These findings suggest that the transdermal dos age form of timiperone prepared from these water-soluble polymers is effective and longer-acting preparations to prevent the emesis associated with anticancer therapy with chemotherapeutic drugs.

View full abstract

Complementary DNA clone encoding the rat small-intestinal oligopeptide transporter, rat PepT1, was isolated from a rat jejunal cDNA library by cross-hybridization with a rabbit PepT1 cDNA probe. The cDNA sequence indicated that rat PepT1 is composed of 710 amino acids and shows 77% and 83% amino acid sequence identity with rabbit and human PepT1, respectively. Hydropathy analysis reveals 12 putative transmembrane domains, with a long (204 amino acids) hydrophilic segment containing five potential N-glycosylation sites between transmembrane domains 9 and 10, in the predicted rat protein. Northern blot analysis detected rat PepTl mRNA in the small intestine and kidney. Complementary RNA (cRNA) of PepT1 was synthesized in vitro transcription and injected into Xenopus laevis oocytes to evaluate its transport function. Uptake of a dipeptide, [¹⁴C] glycylsarcosine by the oocytes was about 10-times higher than that by oocytes injected with water. The cRNA induced-uptake was enhanced in the presence of an inwardly directed proton gradient and was specifically inhibited by dipeptides and tripeptide, whereas their constitutive amino acids, tetra- and penta-peptide were not inhibitory. Accordingly, the isolated clone was confirmed as a rat intestinal proton-coupled oligopeptide transporter, PepT1. Zwitterionic and dianionic cephalosporins, cefadroxil and ceftibuten, were also specifically taken up by the oocytes injected with cRNA, Furthermore, mutual inhibitory effects on the uptakes were observed between glycylsarcosine and these cephalosporins. Hybrid depletion of the expression of rat or rabbit PepT1 in Xenojus laevis oocytes injected with intestinal total mRNA was studied using antisense oligonucleotides corresponding to the 5'-coding region of PepT1. In oocytes injected with both mRNA hybridized with each antisense oligonucleotide, ceftibuten uptakes were almost completely abolished. However, these uptake were not influenced with respective sense oligonucleotide. These results suggest that PepT1 functions for the intestinal absorption of oligopeptides and, β-lactam antibiotics.

View full abstract