Targeting behavior of hepatic artery injected temperature sensitive liposomal adriamycin on tumor-bearing rats

Temperature sensitive liposomal Adriamycin (LADM) was injected into the hepatic artery of rats bearing implanted hepatic tumors. Two hours after the injection, the liver was heated at 42 degrees C and maintained for six minutes at that temperature using local hyperthermia. Blood samples were taken at regular intervals until 8 hours after injection, at which time the animals were sacrificed and the drug distribution in the tissues was examined. Results indicate that the Adriamycin was released from the liposome, with the drug concentration in circulation peaking at 30 minutes after heating. High drug levels (25.2 micrograms/g of wet tissue) in the tumor and high tumor/liver Adriamycin level ratios (TLAR; 4.1) were found. The drug levels and the TLAR of the liposomal Adriamycin injection combined with heating (LADM H) were significantly different from those of the same dose of aqueous Adriamycin with heating (ADM H) or aqueous Adriamycin (ADM) and LADM without heating. The experiment shows that the LADM is cleared from the liver slowly, and when hyperthermia treatment at phase-transition temperature of the liposome is performed, the drug level in an implanted hepatic tumor is increased, and in the parenchyma is decreased. The results imply that targeting the hepatic tumor in this way may be an effective therapeutic method, and the drug release from the liposome may be controlled externally. This method appears promising for clinical practice.     

Organ distribution and antitumor activity of free and liposomal doxorubicin injected into the hepatic artery

Summary The plasma levels, organ distribution, and in vivo antitumor activity of free and liposomal doxorubicin injected into the hepatic artery of rats bearing W256 liver tumors were studied. The administration of liposomal doxorubicin resulted in liver-tumor and liver-parenchyma doxorubicin areas under the curve (AUCs) that were 4.7-and 3.8-fold, respectively, those obtained after the administration of free doxorubicin. Spleen and plasma AUCs were also increased by 2.8 and 2.5 times, respectively, following administration of the liposomal form. In contrast, liposomal doxorubicin did not affect heart AUCs; peak doxorubicin levels in heart tissue were three times lower in animals treated with liposomal doxorubicin. Following treatment with the liposomal form, the cumulative urinary excretion of doxorubicin at 8 h was 38 times lower. In good correlation with these findings, liposomal doxorubicin (2.35 mg/kg on day 7) was more effective than free doxorubicin against liver W256 tumors as measured by tumor-growth inhibition at 5 days after treatment (16% for liposomal doxorubicin versus –53.7% for free doxorubicin,P<0.05) and increased life span (ILS; 108% for liposomal doxorubicin versus 27% for free doxorubicin,P<0.05). These results demonstrate that as compared with free doxorubicin, the administration of liposomal doxorubicin into the hepatic artery results in higher drug levels in the liver tumor and enhanced antitumor activity while maintaining the cardioprotective effect of the liposome carrier as suggested by the decreased peak drug levels measured in the heart tissue.     

Targeting liver tumors by administering liposomal doxorubicin into the hepatic artery.

The plasma levels, organ distribution, and in vivo anti-tumor activity of liposomal doxorubicin administered i.v. or i.a. (hepatic) in rats bearing W256 liver tumors were studied. I.a. administration of liposomal doxorubicin resulted in 4-fold and 1.3-fold higher liver tumor and liver parenchyma doxorubicin levels, respectively, than i.v. administration, thus suggesting a more preferential distribution of liposomal doxorubicin into the liver tumor with i.a. administration. By contrast, the heart, spleen, and plasma AUCs were decreased 3.8-, 3.2-, and 16-fold, respectively, after i.a. administration. Cumulative urinary excretion at 8 hr was also 14 times lower in animals that received liposomal doxorubicin i.a. In good correlation with these findings, i.a. administration markedly enhanced the anti-tumor effect of liposomal doxorubicin against liver W256 tumors as measured by tumor growth inhibition 5 days after treatment (-16% for i.a. administration vs. +89% for i.v. administration, p less than or equal to 0.05) and prolongation of survival (ILS: 108% for i.a. administration vs. 26% for i.v. administration, p less than or equal to 0.05). Our results show that i.a. administration of liposomal doxorubicin results in preferential distribution of the anti-tumor agent into the tumor tissue and increased anti-tumor activity, while increasing the cardioprotective effect of the liposome carrier by decreasing the plasma peak and heart-tissue levels of the drug.     

超选择子宫动脉与外周静脉灌注化疗宫颈癌组织内铂浓度的研究

Objective:The present study is to compare pharmacokinetics difference of carboplatin by using ultraselection uterine artery with by using peripheral vein in cervical cancer. Methods:Thirteen patients with locally advanced cervical cancer who had been proved by pathobiology were randomly divided into two groups:the ultraselection uterine artery group (group A, n=6) and the peripheral vein (group B, n=7). Carboplatin was administered by infusing into artery or vein in both groups at the dosage of 300 mg/m2. Tissues from the cervical tumor were collected at different times after infusion in both groups and then analyzed. Results:The peak concentration of platinum in tumor tissue was about 2.79 times higher in group A than that of group B (P<0.05). The platinum concentrations in tumor in group A reached its peak levels immediately after infusion. But, group B had delayed time. While, for the time point of 0 min, when the administration finished immediately, the platinum concentration in tumor was significantly higher when compared with group B (P < 0.05). The tumor tissue area under the concentration (AUC) of carboplatin was about 2 times higher in group A than that of group B (P < 0.05). Conclusion:We observed the pharmacological advantages of chemotherapy by using ultraselection uterine artery administration of chemo-therapeutic agent carboplatin in tumor tissue which provided theoretical basis and laboratory parameters of the intra-arterial chemotherapy for gynecologic malignancy.     

Analysis and Distribution of Etoposide in Rat Brain Tumor Model: Intracarotid Versus Intracarotid with Angiotensin II—Induced Hypertension

The brain tissue distribution of etoposide has been investigated in 9L gliosarcoma-bearing rats with or without hypertension induced by angiotensin II (AT II). The rat brain tumor models were divided into the following two groups according to etoposide administration route: intracarotid injection (IC) group and intracarotid injection with hypertension induced by AT II (IHIC) group. Ten mg/kg of etoposide was given, and 30 min and 2, 4, 8, and 24 hr later the rats were sacrificed. The drug concentrations in the serum, tumor, and normal brain tissue were analyzed by high-pressure liquid chromatography. The etoposide concentration in the serum, tumor, and normal brain tissue peaked at 30 min in both groups. The serum concentration was similar between the two groups. The etoposide concentration in the tumor was at least 2.2 times higher in the IHIC group than in the IC group at 30 min and 2 hr. The area under drug concentration curve (AUC) in the tumor in the IHIC group was about 2.2 times higher than that in the IC group. The etoposide concentration in the normal brain on the drug injection side changed only slightly from 0.5 hr to 4 hr and was about 3 times higher in the IHIC group than in the IC group. The etoposide concentration in the contralateral normal brain was very low in both groups at 30 min and disappeared thereafter.

Intracarotid injection of anticancer drugs with AT II-induced hypertension further increases the drug concentration and AUC in the tumor compared with intracarotid injection alone and can be useful in treatment of malignant brain tumors.     

Antitumor Activity and Metabolism of a New Anthracycline-containing Fluorine (ME2303) in Lewis Lung Carcinoma-bearing Mice

(7-O-(2,6-Dideoxy-2-fluoro-α-L-talopyranosyl)adriamycmone-14-hemipimerate (ME2303) showed a more marked growth inhibition of Lewis lung carcinoma than adriamycin (ADM). When administered to s.c. Lewis lung carcinoma-hearing mice, ME2303 in the plasma and liver was rapidly metabolized and disappeared. However, ME2303 was incorporated into the tumor at higher concentrations and remained in the tumor for a longer period than in the plasma and liver. ME2303 was metabolized to 7-O-(2,6-dideoxy-2-fluoro-α-L-talopyranosyl) adriamycinone (M1), the product of esterolysis, and its reduced derivative at the C-13 position (M2), Larger amounts of these metabolites were found in the analyzed tissues than in plasma. The maximum concentration of Ml in the tumor was observed at 2 h posttreatment, while the maxima in the plasma and liver were observed at 15 min. On the other hand, i.v. injection of M1 into mice showed a weaker antitumor effect than ME2303 injection, though Ml levels in the plasma and tumor were almost the same as those after administration of ME2303 at the maximum tolerated doses. Some metabolites of ME2303 were found in the tumor after administration of ME2303, but not after administration of M1. ADM remained in the analyzed tissues for a long period and ADM concentrations in the tumor were much higher than in the plasma but less than in the liver. M1 reached a concentration higher than that of ADM in the tumor, opposite to the pattern observed in the liver. The conversion process from ME2303 to M1, the metabolites and their locations in the tumor may be important for the marked antitumor effect of ME2303 in vivo.     

Antitumor activity and metabolism of a new anthracycline-containing fluorine (ME2303) in Lewis lung carcinoma-bearing mice.

(7-O-(2,6-Dideoxy-2-fluoro-alpha-L-talopyranosyl)adriamycinone-14- hemipimerate (ME2303) showed a more marked growth inhibition of Lewis lung carcinoma than adriamycin (ADM). When administered to s.c. Lewis lung carcinoma-bearing mice, ME2303 in the plasma and liver was rapidly metabolized and disappeared. However, ME2303 was incorporated into the tumor at higher concentrations and remained in the tumor for a longer period than in the plasma and liver. ME2303 was metabolized to 7-O-(2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl)adriamycinone (M1), the product of esterolysis, and its reduced derivative at the C-13 position (M2). Larger amounts of these metabolites were found in the analyzed tissues than in plasma. The maximum concentration of M1 in the tumor was observed at 2 h posttreatment, while the maxima in the plasma and liver were observed at 15 min. On the other hand, i.v. injection of M1 into mice showed a weaker antitumor effect than ME2303 injection, though M1 levels in the plasma and tumor were almost the same as those after administration of ME2303 at the maximum tolerated doses. Some metabolites of ME2303 were found in the tumor after administration of ME2303, but not after administration of M1. ADM remained in the analyzed tissues for a long period and ADM concentrations in the tumor were much higher than in the plasma but less than in the liver. M1 reached a concentration higher than that of ADM in the tumor, opposite to the pattern observed in the liver. The conversion process from ME2303 to M1, the metabolites and their locations in the tumor may be important for the marked antitumor effect of ME2303 in vivo.     

A bioassay of cisplatin by human tumor clonogenic assay

A new bioassay method for cis-diamminedichloroplatinum (CDDP) using a human tumor clonogenic assay (HTCA) was developed and used to examine the pharmacokinetics of the active form of CDDP in different schedules of administration. The inhibition of colony growth of tumor cells decreased with increase in the % of fetal calf serum in RPMI1640 containing CDDP. By means of this assay, four administration schedules (A, B, C and D) of CDDP were examined. In patients given 40 mg/m2 of CDDP by iv infusion on day 1 twice with a 1 hr interval (schedule A), total platinum was still detectable in plasma at 6 hr by atomic absorption assay. However, the active form of CDDP was no longer detectable at 30 min. In patients treated with 20 mg/m2 of CDDP iv for 20 min daily (schedule B) from day 1 to day 4, the level of total platinum showed a cumulative increase. However, the active form of CDDP was no longer detectable at 30 min, and no cumulative effect was observed. In patients given a high dose (120 mg/m2) of CDDP iv for 30 min on day 1 (schedule C), the peak concentration of active form of CDDP was determined to be 5.0 to 7.0 micrograms/ml, and a level of more than 1.0 micrograms/ml was maintained even after 2 hr in one case. In 2 patients of this group the concentrations of active form of CDDP determined by HTCA were the same as those of ultrafiltrable platinum detected by atomic absorption assay. In 2 of 3 patients given 100 mg of CDDP into the pleural cavity, the active form of CDDP was detected in sera. High-dose CDDP administration was concluded to be preferable to low-dose therapy because of the higher peak concentration and longer residence time of the active form of CDDP in the plasma. Furthermore, it is suggested that a systemic effect of CDDP can be expected even when CDDP is given by intrapleural administration.     

Pharmacokinetic study of adriamycin in the emulsion mixed with lipiodol-difference resulting from composition and methods of preparation, and behavior after mesenteric arterial injection in rat]

We experimentally investigated the pharmacokinetics of adriamycin (ADM) in a similar of transcatheter arterial chemoembolization therapy (TAE) of hepatocellular carcinoma using emulsion of lipiodol (Lp) mixed with ADM followed by gelatin sponge, and the difference resulting from composition and method of preparation of the emulsion as well as behavior after mesenteric arterial injection in rat. In in vitro study, the emulsion with iopamidol (iopamiron 300 : IP) was more stable than with amidotrizoic acid (60% Urografin : UG). The highest stability was found in the mixing ratio of Lp. IP and distilled water at 1 : 0.42 : 0.08. Frequent pumping also made the emulsion more stable. But in optimally composed emulsion, pumping 20 or 50 times made no difference in the stability during 30 min. which may be longer than the time from preparation to injection time of the emulsion in clinical application. After injection of the emulsion into the mesenteric artery which may simulate injection into the hepatic artery in hepatocellular carcinoma, the arterial blood flow was suspended. In the peripheral arteries the emulsion separated into two phases of Lp and ADM solution, forming striped pattern, and Lp embolization of the peripheral artery persisted for over 45 min. while ADM extravasated. These findings suggest that after Lp-TAE, Lp maintains an embolizing effect while ADM penetrates into the surrounding tumor tissue, and that this is an underlying mechanism for the anti-cancer effect of Lp-TAE.     

The novel highly lipophilic topoisomerase I inhibitor DB67 is effective in the treatment of liver metastases of murine CT-26 colon carcinoma

Colorectal carcinoma occurs in 1 of 20 individuals in most developed countries. The relapse after resection with metastatic liver disease is a major cause of death. 7-t-Butyldimethylsilyl-10-hydroxycamptothecin (DB67) has been incorporated into liposomes allowing for intravenous (i.v.) administration. A preclinical efficacy study of liposomal DB67 was performed using the colon carcinoma CT-26 cell line. The therapeutic dose for DB67 and liposomal DB67 was found to be 7 mg/kg per day using the qdx5/1 schedule. The results are compared with those obtained with irinotecan. The treatment with liposomal DB67 administered intravenously was more effective in reducing the weight and volume of primary spleen tumors and the weight and extent of liver metastases than free DB67 or liposomal DB67 administered intraperitoneally, but less effective than irinotecan. When the primary tumor was resected, treatment with liposomal DB67 administered intravenously was more effective in reducing the weight and extent of liver metastases than DB67 or liposomal DB67 administered intraperitoneally, and irinotecan. DB67 showed a higher accumulation in spleen and liver after its i.v. administration in liposomal form compared with its free or liposomal form administered intraperitoneally. DB67 and liposomal DB67 are more effective than irinotecan in the treatment of liver metastases after resection of the primary tumor.     

Effect of heating order on radiation response of mouse tumor and skin.

The response of C3H mouse mammary adenocarcinomas and skin to irradiation either immediately before, or during heating at 43°C was evaluated. The therapeutic gain factor (TGF) was 1.3 for irradiation during heating, but only 0.9 for irradiation prior to heating. X-irradiation also was done 2 hr before, during or 2 hr after heating at 42.5°C. Heating times were 15, 30 and 60 min. There was no TGF for irradiation following 60 min. heating. When irradiation preceded 1 hr of heating, the TGF was 1.2. Therapeutic gains also were achieved for 30 min. of heating regardless of sequence, although the largest TGF of 1.3 was obtained for simultaneous treatment. TGFs of 1.3 were obtained for 15 min. heating 2 hr prior to or during irradiation. The greater TGFs for shorter heating times resulted from the small effect of heat on skin response, but significant effect on tumor control.     

Sensitizer for photodynamic therapy of cancer: a comparison of the tissue distribution of Photofrin II and aluminum phthalocyanine tetrasulfonate in nude mice bearing a human malignant tumor.

The distribution of Photofrin II (P-II) and aluminum phthalocyanine tetrasulfonate (AIPCS4) in tissues of BALB/c nu/nu nude mice bearing the LOX human melanoma was measured fluorimetrically at different times after intraperitoneal injection of the drugs, 20 mg/kg body weight. The plasma levels of the drugs as well as the excretion in feces and urine were also determined. The plasma concentrations of both drugs were found to build up in a similar manner during the first 30 min after injection. Thereafter, the plasma level of AIPCS4 decreased exponentially with an elimination half-life of 1.5 hr. The kinetics of elimination of P-II from the plasma were consistent with a 2-compartment model, with 90% of sensitizer lost with a half-life of about 5 hr, and the remaining fraction with a half-life of 30 hr. About 80% of the injected dose of P-II was excreted in the feces during the 7-days following injection, while 77% of AIPCS4 was excreted in the urine during the same period. After injection of a dose of 20 mg/kg, the concentrations of P-II in the LOX tumor as well as in the skin, muscle, brain, heart, lung, kidney and liver increased for about 24 hr, then remained constant or decreased slowly for the next 48 hr, after which they decreased slightly faster. On the other hand, the concentrations of APICS4 in most tissues as well as in the tumor peaked at about 30 min, then decreased with a half-life of between 1.5 and 3 hr. The tumor/skin concentration ratio was about 1 for both drugs (1-24 hr after injection). The tumor/muscle concentration ratio was about 2 for P-II at all sampling times, and maximally 10 (at 18 hr after injection) for AIPCS4. In the present tumor model, the tumor/tissue concentration ratio for all tissues at 1 hr and at 24 hr after the injection was equal for the 2 drugs or higher for AIPCS4.     

Studies on liposomal ferromagnetic particles and a technique of high frequency inductive heating--in vivo studies of rabbits

The tumor can be more selectively heated by applying of high frequency inductive heating after administration of ferromagnetic particles into a tumor. In order to devise a technique used for the selective hyperthermia of a tumor with high frequency inductive heating, we continued fundamental studies using liposomal ferromagnetic particles (HP-LM), which were prepared as follows: triiron tetoraoxide (Fe3O4) particles were coated with liposomal membrane contained hematoporphyrin with neoplastic affinity. In Vivo Studies of Rabbits: We used high frequency inductive heater (NIHON KOSHUHA CO. LTD. YKN-10), frequency: 400 kHz, out put: 10 kW, coil diameter: 90 mm. VX-2 tumor cells at 1.5 X 10(7) were implanted to the lower thigh of rabbit. When the implanted tumor grew up 3 cm in diameter, A-D group were heated and studied. Group A: In a dose of 200 mg/kg of HP-LM was administered into the femoral artery, Group B: In a dose of 100 mg/kg of Fe3O4 was administered into the femoral artery, Group C: Ligation of femoral artery, Group D: Nonadministrated, and then was immediately heated. Group A: In a dose of 200 mg/kg of HP-LM, with heating for 10 minutes, temperature was elevated 14. 8 degrees C at center of tumor. Group B: In a dose of 100 mg/kg of Fe3O4, with heating for 10 minutes, temperature was elevated 10.6 degrees C at center of tumor. Group C: In a ligation of femoral artery, with heating for 10 minutes, temperature was elevated 6.5 degrees C at center of tumor.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biodistribution of lymphokine-activated killer (LAK) cells in Wag rats after hepatic-artery or jugular-vein infusion.

This study deals with the biodistribution of syngeneic radiolabeled lymphokine-activated killer (LAK) cells in Wag rats after infusion via the hepatic artery or the jugular vein. The biodistribution of 111Indium-labeled LAK cells was evaluated using serial whole-body gamma camera imaging. Furthermore, we investigated 2 factors that might influence the biodistribution of these effector cells: purity of LAK cells and administration of interleukin-2 (IL-2). After injection of 111Indium-labeled LAK cells via the hepatic artery or via the jugular vein we could detect important differences in the biodistribution pattern up to 5 hr after injection. LAK cells administered via the jugular vein were all found in the lungs up to 2 hr after injection and then redistributed to the liver and to the spleen. LAK cells administered via the hepatic artery were all found in the liver after injection and redistributed after 2 hr mainly to the spleen. About 8 hr after injection we could no longer detect any differences in the biodistribution pattern according to the route of administration. Biodistribution was followed for up to 72 hr after injection but the pattern showed no change after 8 hr, whichever the route of administration. A purified adherent-LAK population, a large granular lymphocyte culture with only 6% T cells, showed the same distribution pattern as standard LAK cells (40% T cells). Infusions of 40,000 units of IL-2 per day, starting 3 days before and continuing after administration of radio-labeled LAK cells, accelerated the redistribution of these cells by both routes of administration. We conclude that up to 2 hr after local infusion, a high concentration of LAK cells in the first capillary bed can be obtained. Therefore, local administration of LAK cells may be more effective against tumors.     

Cellular pharmacology of MX2, a new morpholino anthracycline, in human pleiotropic drug-resistant cells

We previously reported that MX2, a new morpholino anthracycline, showed marked effects on pleiotropic drug-resistant sublines of murine P388 leukemia in vivo as well as in vitro. In this study we examine the in vitro cytotoxicity against pleiotropic drug-resistant sublines of human tumor cell lines. MX2 was effective against multidrug-resistant sublines of four human tumor cell lines; these cells, having a 4.8- to 200-fold cross-resistance to Adriamycin (ADM) showed only a 0.7- to 2.3-fold resistance to MX2 compared with the sensitive cells. To elucidate the mechanism by which MX2 overcomes multidrug resistance, the intracellular pharmacology of MX2 in human myelogenous leukemia K562 and its ADM-resistant subline (K562/ADM) was examined. Both K562 and K562/ADM cells accumulated MX2 more easily than ADM, and the intracellular accumulation of MX2 attained a steady state in both cell lines within 30 min of incubation at 37 degrees C. The amount of MX2 that accumulated in K562/ADM at a steady state was only 1.3 times lower than that in K562. However, ADM was accumulated slowly in both cell lines compared with MX2, and the intercellular concentration reached a steady state in K562/ADM after 90 min of incubation and in K562 after more than 120 min. K562/ADM cells accumulated a 3.3-fold lower concentration of ADM than K562 after 120 min of exposure. The steady-state concentration of ADM in K562/ADM was 8.3 times lower than that of MX2. In addition, greater than 70% of MX2 was retained in both cell lines after 150 min of incubation in the absence of this drug. Verapamil, a calcium antagonist, hardly augmented the cytotoxicity of MX2 against K562/ADM, and no distinct effect of this drug on both the time course and the maximal level of accumulation of MX2 was observed. Interestingly, MX2 effectively inhibited ATP/Mg2(+)-dependent [3H]vincristine binding to K562/ADM membrane preparations, indicating that MX2 could be transported outside the cell by an active efflux pump. The high intracellular accumulation and retention of MX2 in K562/ADM through the rapid influx of the drug into the cells may be one of the reasons why MX2 circumvents pleiotropic drug resistance.     

Pharmacokinetics of 5-fluorouracil following hepatic intra-arterial infusion in a VX2 hepatic metastasis model

BACKGROUND: Hepatic intra-arterial infusion chemotherapy of 5-fluorouracil (5-FU) or fluorodeoxyuridine (FUDR) has been a treatment option for liver metastasis from colorectal cancer. However, an optimal administration schedule of 5-FU is still controversial. This study was conducted to evaluate a suitable schedule from the viewpoint of 5-FU metabolites and related enzymes. METHODS: 5-FU was infused into the hepatic artery of rabbits having hepatic deposits of VX2 tumor cells in a daily dose of 1, 4, or 8 mg/kg using various schedules. 5-FU, Thymidylate synthase (TS), TS inhibition rate (TSIR), and the amount of fluoro-RNA (F-RNA) were measured. RESULTS: A high concentration of 5-FU was detected in the tumors of the group that was administered a dose of 8 mg/kg. TSIR in the tumor was about two-fold higher in the rabbits that were administered a total dose of 8 mg/kg than in those that were administered doses of 4 mg/kg or less. F-RNA, ranging from 27 to 36 ng/mg RNA, was detected in the tumor of the rabbits that were administered a total dose of 8 mg/kg. No difference was observed between the short period and the continuous administration schedules of rabbits that were administered a dose of 8 mg/kg of 5-FU. However, DNA synthesis inhibition in normal hepatic tissue was more dependent on the administration schedule than on the total dose of 5-FU because TSIR was significantly higher with shorter periods of drug administration. CONCLUSION: Intermittent bolus administration of large doses of 5-FU might cause more severe hepatic impairment than continuous administration. These results suggest that hepatic intra-arterial infusion of 5-FU should be administered continuously for liver metastasis, although further experiments including a longer administration period of 5-FU are required.     

Efficacy of liposomes and hyperthermia in a human tumor xenograft model: importance of triggered drug release

The tumor drug concentrations, drug distributions, and therapeutic efficacies achieved by three fundamentally different liposomes, nonthermosensitive liposome (NTSL), traditional thermosensitive liposome (TTSL), and low temperature sensitive liposome (LTSL); free doxorubicin (DOX); and saline in combination with hyperthermia (HT) were directly compared in a human tumor xenograft model. NTSL is a nonthermosensitive liposome in the physiological temperature range, TTSL is a traditional thermosensitive liposome that triggers in the range of approximately 42-45 degrees C and releases drug over approximately 30 min, and LTSL is a new low temperature sensitive liposome that triggers in the range of approximately 39-40 degrees C and releases drug in a matter of seconds. Because of the different attributes of the liposomes, it was possible to delineate the relative importance of liposome drug encapsulation, HT cytotoxicity, HT-drug interaction, HT-induced liposomal delivery, and HT-triggered liposomal drug release in achieving antitumor activity. Athymic nude mice bearing the FaDu human tumor xenograft were given a single i.v. dose of 5 mg/kg of DOX (free drug or liposome encapsulated), and the tumors were then heated to either 34 degrees C or 42 degrees C for 1 h at 34 degrees C. All treatment groups were similar, achieving low concentrations of DOX (0-4.5 ng/mg). At 42 degrees C, the LTSL (25.6 ng/mg) achieved the highest DOX concentration (P < 0.04), but all three liposomal formulations (7.3-25.6 ng/mg) were higher than saline or DOX (0-0.7 ng/mg; P < 0.02). LTSL + HT was also the only group that resulted in significant amounts of DNA-bound DOX (silver nitrate-extractable fraction; P < 0.02). Tumor tissue sections were visualized for DOX fluorescence to investigate the local distribution of the drug in the tumor and confirm the relative drug concentrations based on fluorescence intensity. There was relatively little fluorescence seen with treatment groups at 34 degrees C. At 42 degrees C, the LTSL showed the most DOX fluorescence (P < 0.01), and the fluorescence, although not homogeneous, was pervasive throughout the tumor sections. Therapeutic efficacy of treatments was determined from tumor growth time. At 34 degrees C, the only treatment group significantly better than the saline group (9.8 days) was the NTSL group, with a growth time of 20.9 days (P < 0.02). At 42 degrees C, all three liposomal formulations were more efficacious than DOX. LTSL + HT had the longest growth time (51.4 days) and the most number of local controls at 60 days (six of nine tumors). With HT, the DOX concentrations and fluorescence were tightly correlated with tumor growth delay, indicating that adequate (increased) drug delivery can be predictive of therapeutic effect. Overall, the LTSL + HT group showed the largest DOX concentration, the highest and most pervasive DOX fluorescence, and the most antitumor effect. Thus, HT-triggered liposomal drug release may account for the largest differential therapeutic effect and demonstrates the importance of rapid drug release from the drug carriers at the tumor site.     

Optimizing photodynamic therapy: in vivo pharmacokinetics of liposomal meta-(tetrahydroxyphenyl)chlorin in feline squamous cell carcinoma.

PURPOSE: The aim of the present study was to optimize and simplify photodynamic therapy using a new liposomal formulation of the photosensitizer meta-(tetrahydroxyphenyl)chlorin [m-THPC (Foscan); liposomal m-THPC (Fospeg)] and to reduce systemic reactions to the photosensitizer. EXPERIMENTAL DESIGN: To examine the pharmacokinetics of liposomal m-THPC, we determined tissue and plasma variables in feline patients with spontaneous squamous cell carcinoma. In vivo fluorescence intensity measurements of tumor and skin were done with a fiber spectrophotometer after i.v. injection of m-THPC or liposomal m-THPC in 10 cats. Blood samples, drawn at several time points after photosensitizer administration, were analyzed by high-performance liquid chromatography. RESULTS: None of the liposomal m-THPC-treated cats showed side effects during or after drug injection. Fluorescence intensities, fluorescence ratios (tumor fluorescence divided by skin fluorescence), and bioavailability in the tumor were 2 to 4 times higher with liposomal m-THPC compared with m-THPC. Liposomal m-THPC concentration in the tumor increased constantly to reach a maximum at 4 hours after injection. Plasma concentration and bioavailability were approximately 3 times higher with liposomal m-THPC compared with m-THPC measured at the time points of highest plasma concentration. The distribution half-life was shorter with liposomal m-THPC, resulting in maximal tumor accumulation up to 5.5 times earlier. Maximal tumor accumulation and maximal fluorescence ratio with liposomal m-THPC occurred at the same time point, indicating maximal selectivity. In both groups, all cats responded to therapy. CONCLUSIONS: Liposomal m-THPC was well tolerated by all cats and seems to have superior pharmacokinetic properties compared with m-THPC. The efficacy of the drug warrants further study.     

Cellular and plasma adriamycin concentrations in long-term infusion therapy of leukemia patients

Summary To determine whether long-term adriamycin (ADM) infusions resulted in cellular ADM concentrations at least comparable to those observed after bolus injections, ADM cellular and plasma concentrations were measured in 18 patients with leukemia. ADM was administered at 30 mg/m² per day for 3 days, either as bolus injections or as 4-, 8-, or 72-h infusions. Negligible accumulation of plasma ADM was observed. Peak plasma ADM concentrations after bolus injections were 1640±470 ng/ml (n=7). Maximum levels were 176±34 ng/ml during 4-h infusion (n=5); 85±50 ng/ml during 8-h infusion (n=4); and 47±5 ng/ml (n=2) after 72-h infusion. ADM concentrations in nucleated blood and bone marrow cells correlated well (r=0.82, n=47). ADM accumulated in leukemic cells up to 30–100 times the plasma concentrations. The shorter the administration time-span, the higher the peak leukemic cell concentration and the greater the loss of drug immediately after the end of the administration. The final cellular ADM half-life was approximately 85–110 h. After long-term infusion and bolus injection of the same dose, similar areas under the curve for plasma or leukemic blast cell ADM concentrations were attained. Since comparable therapeutic efficacy was observed in all regimens, the antileukemic effect appeared not to be related to the peak plasma concentrations, while acute toxicity phenomena decreased with increasing duration of the infusion. Long-term ADM infusion deserves more attention in the treatment of patients with anthracyclines.Supported by the Queen Wilhelmina Foundation (The Netherlands Cancer Foundation, grant SNUKC 82-7), The Ank van Vlissingen Foundation and The Maurits and Anna de Kock Foundation     

Direct comparison of liposomal doxorubicin with or without polyethylene glycol coating in C-26 tumor-bearing mice: is surface coating with polyethylene glycol beneficial?

Sterically stabilized liposome is characterized by a surface coating of polyethylene glycol (PEG) or other polymers that can reduce opsonization of the liposome by plasma proteins. It has a higher plasma area under the concentration-time curve (AUC), which is believed to correlate with better therapeutic efficacy. However, the presence of large molecules on the liposomal surface may reduce the interactions of liposomes with cells and hinder entry of liposomes into the tumor tissue. Using a stable liposomal system composed of distearoyl phosphatidylcholine/cholesterol, we examined the effect of PEG (Mr 2000) on the pharmacokinetics and on the efficacy of liposomal doxorubicin with C-26 syngeneic tumor model in BALB/c mice. The plasma AUC of liposomal doxorubicin with 6 mol-% PEG-modified distearoyl phosphatidylethanolamine (PEG-DSPE) was approximately twice that of liposomal doxorubicin without PEG at various dosages, regardless of whether the mice were tumor-bearing. Paradoxically, the group of mice treated with liposomal doxorubicin without PEG had higher tumor doxorubicin concentrations. The 72-h tumor AUC was 1.44 times that of liposomal doxorubicin with 6% PEG-DSPE. The tumor-accumulation efficiency (AUC(Tumor)/AUC(Plasma)) of liposomal doxorubicin without PEG was 0.87, and this was more than twice that of the liposomal doxorubicin with 6% PEG-DSPE (0.31). At a dose of 10 mg/kg, although both liposomal groups were better than the free drug group in terms of clinically relevant parameters, including toxicity, tumor shrinkage, and survival, there was no difference between the two liposomal drug groups. In this stable liposome system, surface coating with PEG offered no benefit for liposomal doxorubicin in the C-26 tumor model. To enhance the therapeutic index of liposomal doxorubicin, simply increasing plasma AUC by surface coating with PEG may not be satisfactory.