YM155, a novel survivin suppressant, enhances taxane-induced apoptosis and tumor regression in a human Calu 6 lung cancer xenograft model

Survivin, an apoptotic inhibitor, is overexpressed in the majority of human tumor types and represents a novel target for anticancer therapy. Taxanes induce a mitotic cell-cycle block through the inhibition of microtubule depolymerization, with subsequent elevated expression/stabilization of survivin. We investigated the administration of survivin suppressant YM155 monobromide (YM155), in combination with docetaxel, in a human non-small-cell lung cancer (NSCLC) xenograft model. Animals received a 7-day continuous infusion of YM155, 2 mg/kg, and/or three bolus doses of docetaxel, 20 mg/kg, according to three dosing schedules: YM155 administered concomitantly with docetaxel, before docetaxel, and after docetaxel. YM155 administered either concomitantly with or before docetaxel showed significant antitumor activity (tumor regression ≥ 99%), with complete regression of the established human NSCLC-derived tumors in mice (eight of eight and seven of eight animals, respectively). Significantly fewer complete responses (three of eight animals) were achieved when YM155 was administered after docetaxel. No statistically significant decreases in body weight were observed in the combination versus docetaxel groups. YM155 administered concomitantly with docetaxel resulted in significant decreases in mitotic and proliferative indices, and in a significant increase in the apoptosis index. Elevated survivin expression was seen in tumors from mice treated with docetaxel alone; a significant reduction in survivin expression was seen in tumors from mice treated with YM155 alone or in combination with docetaxel, but not in the control group. These results indicate that in a human NSCLC xenograft model YM155 in combination with docetaxel diminished the accumulation of survivin by docetaxel and induced more intense apoptosis and enhanced antitumor activity, compared with single-agent YM155 or docetaxel.     

Combination of oral fluoropyrimidine and docetaxel: reappraisal of synergistic effect against gastric carcinoma xenografts

BACKGROUND: The synergistic antitumor effect of a combination of docetaxel and capecitabine is reported to be attributable to docetaxel-mediated up-regulation of thymidine phosphorylase (dThdPase). MATERIALS AND METHODS: Intravenous docetaxel (15 mg/kg) was given to nude mice bearing xenografts of the gastric cancer cell lines MKN45 and MKN28. Mice were sacrificed on days 7, 10 and 22 and tumor samples were taken to measure the activities of thymidylate synthase, dihydropyrimidine dehydrogenase, dThdPase and orotate phosphoribosyltransferase. The efficacy of capecitabine or S-1, alone and in combination with docetaxel, was then evaluated in vivo. Docetaxel was administered intravenously on days 8 and 22 at 15 mg/kg, while capecitabine (269 mg/kg) or S-1 (7.5 mg/kg) were administered orally 5 times a week for 4 weeks. RESULTS: Tumor regression was observed only for a combination of capecitabine and docetaxel against MKN28, while additive growth inhibition was obtained by the combination of docetaxel and both S-1 and capecitabine on MKN45 tumor xenografts. Induction of dThdPase activity was observed only for MKN45. The activity of no other enzyme was significantly affected following administration of docetaxel. CONCLUSION: The combination of oral fluoropyrimidine and docetaxel showed augmented antitumor activity, but this may be attributed to mechanisms other than changes in 5-fluorouracil-metabolizing enzymes.     

Antitumor activity of erlotinib (OSI-774, Tarceva) alone or in combination in human non-small cell lung cancer tumor xenograft models

Our objective was the preclinical assessment of the pharmacokinetics, monotherapy and combined antitumor activity of the epidermal growth factor receptor (HER1/EGFR) tyrosine kinase inhibitor erlotinib in athymic nude mice bearing non-small cell lung cancer (NSCLC) xenograft models. Immunohistochemistry determined the HER1/EGFR status of the NSCLC tumor models. Pharmacokinetic studies assessed plasma drug concentrations of erlotinib in tumor- and non-tumor-bearing athymic nude mice. These were followed by maximum tolerated dose (MTD) studies for erlotinib and each chemotherapy. Erlotinib was then assessed alone and in combination with these chemotherapies in the NSCLC xenograft models. Complete necropsies were performed on most of the animals in each study to further assess antitumor or toxic effects. Erlotinib monotherapy dose-dependently inhibited tumor growth in the H460a tumor model, correlating with circulating levels of drug. There was antitumor activity at the MTD with each agent tested in both the H460a and A549 tumor models (erlotinib 100 mg/kg: 71 and 93% tumor growth inhibition; gemcitabine 120 mg/kg: 93 and 75% tumor growth inhibition; cisplatin 6 mg/kg: 81 and 88% tumor growth inhibition). When each compound was given at a fraction of the MTD, tumor growth inhibition was suboptimal. Combinations of gemcitabine or cisplatin with erlotinib were assessed at 25% of the MTD to determine efficacy. In both NSCLC models, doses of gemcitabine (30 mg/kg) or cisplatin (1.5 mg/kg) with erlotinib (25 mg/kg) at 25% of the MTD were well tolerated. For the slow growing A549 tumor, there was significant tumor growth inhibition in the gemcitabine/erlotinib and cisplatin/erlotinib combinations (above 100 and 98%, respectively), with partial regressions. For the faster growing H460a tumor, there was significant but less remarkable tumor growth inhibition in these same combinations (86 and 53% respectively). These results show that in NSCLC xenograft tumors with similar levels of EGFR expression, the antitumor activity of erlotinib is robust both as monotherapy and in combination with chemotherapies.     

Targeting the tumor vasculature: enhancing antitumor efficacy through combination treatment with ZD6126 and ZD6474

BACKGROUND: The antitumor efficacy of combination therapy of the vascular disrupting agent ZD6126 and antiangiogenic agent ZD6474 was evaluated in the models of human colorectal (HT29) and ovarian carcinoma (OW1). MATERIALS AND METHODS: HT29 and OW1 xenograft-bearing mice were treated with ZD6126 and ZD6474 either alone or in combination. ZD6126 therapy consisted of three doses of 100 mg/kg administered 1, 3 and 5 days after the tumor reached the starting size. ZD6474 was administered daily at a dose of 25 mg/kg on days 1-5. RESULTS: ZD6126 and ZD6474 treatment alone only resulted in modest tumor growth delay. However, significantly enhanced antitumor effects were observed in the combination treatment. CONCLUSION: The combination of the vascular disrupting with the antiangiogenic agent led to significant enhancement of antitumor efficacy in HT29 and OW1 human tumor models. Such combination therapy may have significant therapeutic benefit even in tumors insensitive to either treatment alone.     

Chemosensitization by antisense oligonucleotides targeting MDM2

The MDM2 oncogene is overexpressed in many human cancers, including sarcomas, certain hematologic malignancies, and breast, colon and prostate cancers. The p53-MDM2 interaction pathway has been suggested as a novel target for cancer therapy. To that end, several strategies have been explored, including the use of small polypeptides targeted to the MDM2-p53 binding domain, anti-MDM2 antisense oligonucleotides, and natural agents. Different generations of anti-human-MDM2 oligonucleotides have been tested in in vitro and in vivo human cancer models, revealing specific inhibition of MDM2 expression and significant antitumor activity. Use of antisense oligos potentiated the effects of growth inhibition, p53 activation and p21 induction by several chemotherapeutic agents. Increased therapeutic effectiveness of chemotherapeutic drugs in human cancer cell lines carrying p53 mutations or deletions have shown the ability of MDM2 inhibitors to act as chemosensitizers in various types of tumors through both p53-dependent and p53-independent mechanisms. Inhibiting MDM2 appears to also have a role in radiation therapy for human cancer, regardless of p53 status, providing a rationale for the development of a new class of radiosensitizers. Moreover, MDM2 antisense oligonucleotides potentiate the effect of epidermal growth factor receptor (EGFR) inhibitors by affecting in vitro and in vivo proliferation, apoptosis and protein expression in hormone-refractory and hormone-dependent human prostate cancer cells. These data support the development, among other MDM2 inhibitors, of anti-MDM2 antisense oligonucleotides as a novel class of anticancer agents, and suggest a potentially relevant role for the oligonucleotides when integrated with conventional treatments and/or other signaling inhibitors in novel therapeutic strategies.     

Introduction of antisense oligonucleotides to heat shock protein 47 prevents pulmonary fibrosis in lipopolysaccharide-induced pneumopathy of the rat

Acute respiratory distress syndrome (ARDS) confers high morbidity, and in part due to pulmonary fibrosis. The 47-kDa heat shock protein 47 (HSP 47) is a collagen-specific molecular chaperone that has been shown to play a major role in the processing and secretion of procollagen. We examined the effect of antisense oligonucleotides against HSP 47 in Wistar rats with lipopolysaccharide (LPS)-induced pulmonary fibrosis. These rats expressed heat shock protein (HSP) 47 and collagen in response to LPS. The distribution of HSP 47 was similar to that of collagen, and all control rats displayed pulmonary fibrosis after intratracheal administration of 20 mg/kg LPS alone. Antisense oligonucleotides (100 nmol/kg dissolved in saline) were administered with the LPS among experimental subjects. Subsequent immunoblot analysis confirmed the inhibition of HSP 47 by the administration of antisense oligonucleotides. The oligonucleotides significantly improved pulmonary fibrosis among those rats administered LPS, but the oligonucletides themselves did not produce any significant changes in the behavior or histology of the lungs among control rats. These findings suggest that HSP 47 antisense oligonucleotides improve lung fibrosis among rats with LPS-induced pneumopathy.     

Cryptophycin 52 and cryptophycin 55 in sequential and simultaneous combination treatment regimens in human tumor xenografts

The antitumor activity of cryptophycin 52 (C52) and cryptophycin 55 (C55) in sequential and simultaneous combination treatment regimens in human tumor xenografts models was explored. The antitumor activity of C52 and C55 was compared alone and in sequential combination with gemcitabine or paclitaxel in four lung cancer models, H460 and Calu-6 NSCLC and SW2 and H82 small cell lung carcinoma. The combination of C52 followed by gemcitabine was additive in three tumors and greater-than-additive in the fourth. The combination of C55 followed by gemcitabine was additive in three tumors and less-than-additive in the fourth. The combination of C52 followed by paclitaxel was greater-than-additive in one tumor, additive in one tumor and less-than-additive in two tumors. The combination of C55 followed by paclitaxel was greater-than-additive in two tumors and less-than-additive in two tumors. The simultaneous combination of C52 or C55 with fractionated radiation therapy was assessed in the H460 NSCLC tumor. Both cryptophycins produced a tumor response that was additive along with radiation therapy. The HCT116 colon carcinoma was used to compare the antitumor activity of simultaneous or sequential combination of 5-fluorouracil or irinotecan with C52. C52 produced greater-than-additive tumor response when administered either simultaneously with or sequentially with 5-fluorouracil or iriniotecan. Finally, when administered to animals bearing intraperitoneal OVCAR-3 ovarian carcinoma, C52, docetaxel and paclitaxel resulted in mean survival times of 123, 80 and 85 days compared with 72 days in the untreated controls. In combination with carboplatin, C52, docetaxel and paclitaxel resulted in mean survival times of 140, 105 and 135 days. Cryptophycins have the potential to be useful chemotherapeutic agents in a wide variety of clinical combinations regimens.     

Antitumor activity of doxorubicin in combination with docetaxel against human breast cancer xenografts

In this study we assessed the in vivo antitumor activity of combined docetaxel (DOCE) and doxorubicin (DXR) treatment using 2 human breast carcinoma cell xenografts (R-27 and MX-1) in the nude mouse model. The transplanted tumors were allowed to reach exponential growth, whereupon 10 or 40 mg DOCE per kg alone (i.p.), 8 mg DXR per kg alone (i.v.), or 10 mg/kg DOCE (i.p.) and 8 mg/kg of DXR (i.v.), in the sequence of DOCE followed by DXR, were administered. The in vivo antitumor activity of combined DOCE and DXR was synergistic against R-27 and additive against MX-1. P-glycoprotein (P-gp) was detected immunohistochemically, and was highly expressed in R-27, but not in MX-1. In conclusion, DOCE may increase the antitumor activity of DXR against P-gp-positive breast cancer xenografts, such that the DOCE and DXR combination may be a useful treatment in clinical breast cancer.     

Cryptophycins: a novel class of potent antimitotic antitumor depsipeptides

The antitumor cryptophycins are synthetic derivatives of the desipeptide cryptophycins isolated from the cyanobacterium Nostoc sp. Cryptophycin 52 that is currently in clinical trial in solid tumors, is prepared by total synthesis of four key fragments that are coupled to form the final product. The mechanism of anticancer activity of the cryptophycins has been associated with their destabilization of microtubules and with their induction of bcl-2 phosphorylation leading to apoptosis. The cryptophycins maintain activity against ovarian and breast carcinoma cells that overexpress the multidrug resistance efflux pump P-glycoprotein. Cryptophycin 52 has demonstrated a broad range of antitumor activity against both murine and human tumors. In the human MX-1 breast carcinoma xenograft cryptophycin 55 produced greater-than- additive tumor response in combination with 5-fluorouracil. In human non-small cell lung carcinoma and human small cell carcinoma xenografts, administration of the cryptophycins along with gemcitabine, cisplatin or carboplatin resulted in antitumor activity greater than either agent alone. The cryptophycins appear to be additive with fractionated radiation therapy in the human H460 non-small cell lung carcinoma. In the human HCT116 colon carcinoma, the cryptophycins resulted in a greater than additive tumor response when administered sequentially with 5-fluorouracil or irinotecan. Treatment of animals bearing intraperitoneal human OVCAR-2 ovarian carcinoma with cryptophycin 52 resulted in survival times that were greater than those achieved with docetaxel or paclitaxel. Cryptophycin 52 is currently in early clinical testing.     

Adjuvant effect of docetaxel on HPV16 L2E6E7 fusion protein vaccine in a mouse model

We previously demonstrated that the antineoplastic agent docetaxel enhanced the immune response to an influenza vaccine. This study evaluated the adjuvant effect of docetaxel (DOC) on the therapeutic efficacy of HPV16 L2E6E7 fusion protein (HPV-LFP) in mice inoculated with TC-1 cells. The results demonstrated that docetaxel significantly enhanced the therapeutic effect of HPV-LFP on TC-1 cell-induced tumors in mice. The injection of HPV-LFP in combination with docetaxel in TC-1 tumor-bearing mice significantly reduced tumor volume and weight, and a greater percent survival was detected than mice treated with HPV-LFP alone. The inhibition of tumors was associated with significantly increased serum antigen-specific IgG and isotypes, activated CTLs, increased IFN-γ-secreting T cells, and decreased Treg cells and IL-10-secreting cells in spleen. In addition, down-regulation of IL-10, VEGF and STAT3, up-regulation of IFN-γ and decreased Treg cells in the tumor microenvironment may also important contributing factors to the antitumor effect. It may be valuable to use a DOC-containing water to dilute HPV-LFP powder before injection in patients because of its excellent adjuvant effect on HPV-LFP and solubility in water.     

Synergy of Irofulven in combination with various anti-metabolites,enzyme inhibitors,and miscellaneous agents in MV522 lung carcinoma cells: marked interaction with gemcitabine and 5-fluorouracil

The novel agent Irofulven (HMAF, NSC 683863) has demonstrated significant antitumor activity against solid tumors in various xenograft models and human clinical trials. The antitumor potential of combining irofulven with 72 different anti-metabolite, enzyme inhibiting, and miscellaneous agents was investigated in this study. The human lung carcinoma MV522 cell line and its corresponding xenograft model were used to evaluate the activity of irofulven in combination with these different agents. Irofulven in combination with select anti-metabolites, notably cytidine or adenine-derived agents, displayed strong synergistic activity in both in vitro and in vivo studies. Agents demonstrating strong synergistic interaction with irofulven included gemcitabine, cyclocytidine, cytarabine, fludarabine phosphate, cladribine, and 5-fluorouracil. Other anti-metabolites, enzyme inhibitors, and a variety of miscellaneous agents failed to interact beneficially when administered in combination with irofulven. The therapeutic activity of irofulven is enhanced considerably when irofulven is combined with select anti-metabolite agents, and further clinical evaluation of these combinations is warranted. The synergistic interaction with these combinations may stem from a variety of actions including inhibition of the nucleotide excision repair (NER) pathway, topoisomerase I activity, and caspase-dependent and independent induction of apoptosis.     

Biochanin A Inhibits Breast Cancer Tumor Growth in A Murine Xenograft Model

PURPOSE: Our objective was to determine the effect of the flavonoid biochanin A (BCA), administered alone or in combination with the flavonoids quercetin and epigallocatechin-3-gallate (EGCG), on the growth of human breast cancer MCF-7 cells in a murine xenograft animal model. MATERIALS AND METHODS: MCF-7 tumors were implanted into mice and groups of mice were treated with vehicle, BCA at 2 doses (5 or 15 mg/kg), quercetin and EGCG (5 mg/kg each), or BCA combined with quercetin and EGCG (5 mg/kg each). The flavonoids were injected once daily intraperitoneally, with treatment starting 4 weeks prior to cell inoculation. RESULTS: Treatment with 15 mg/kg of BCA or the mixture of the 3 flavonoids resulted in a reduction in tumor incidence. Tumor size in xenograft mice treated with 15 mg/kg BCA was significantly smaller than in the control group. Although quercetin/EGCG administration did not affect tumor size, treatment with the mixture of the 3 flavonoids at doses of 5 mg/kg produced similar effects as seen with 15 mg/kg BCA. CONCLUSIONS: Our findings indicate that BCA inhibits tumor growth in a xenograft animal model; BCA may represent a breast cancer preventive agent, either administered alone or in combination with other flavonoids.     

EDTA enhances the antitumor efficacy of intratumoral cisplatin in s.c. grafted rat colon tumors

We have investigated whether EDTA, a calcium chelator, could improve the accumulation of platinum in tumors and enhance the antitumor efficacy by increasing drug diffusion through the extracellular tumor matrix. Intratumoral injection of 0.3 mg/kg cisplatin combined with 10 mg/ml EDTA in 2 ml saline serum led to tumor cure in four of eight rats and produced major tumor regression in the other animals. In contrast, intratumoral injection of cisplatin alone or EDTA alone had no antitumoral effect. EDTA increased platinum accumulation both in vivo and ex vivo in the PROb tumors. EDTA alone was cytotoxic at a concentration of 10 mg/ml, but neither increased platinum accumulation nor cisplatin toxicity on cultured PROb colonic cancer cells. We conclude that EDTA could be a useful and well-tolerated adjuvant for enhancing intratumoral cisplatin chemotherapy.     

Enhancing Tumor Drug Distribution With Ultrasound-Triggered Nanobubbles

Issues with limited intratumoral drug penetration and heterogeneous drug distribution continue to impede the therapeutic efficacy of nanomedicine-based delivery systems. Ultrasound (US)-enhanced drug delivery has emerged as one effective means of overcoming these challenges. Acoustic cavitation in the presence of nanoparticles has shown to increase the cellular uptake and distribution of chemotherapeutic agents in vivo. In this study, we investigated the potential of a drug-loaded echogenic nanoscale bubbles in combination with low frequency (3 MHz), high energy (2 W/cm²) US for antitumor therapy. The doxorubicin-loaded nanobubbles (Dox-NBs) stabilized with an interpenetrating polymer mesh were 171.5 ± 20.9 nm in diameter. When used in combination with therapeutic US, Dox-NBs combined with free drug showed significantly higher (*p < 0.05) intracellular uptake and therapeutic efficacy compared with free drug. When injected intravenously in vivo, Dox-NBs + therapeutic US showed significantly higher (*p < 0.05) accumulation and better distribution of Dox in tumors when compared with free drug. This strategy provides an effective and simple method to increase the local dose and distribution of otherwise systemically toxic chemotherapeutic agents for cancer therapies.     

Protein-intrinsic and signaling network-based sources of resistance to EGFR- and ErbB family-targeted therapies in head and neck cancer

Agents targeting EGFR and related ErbB family proteins are valuable therapies for the treatment of many cancers. For some tumor types, including squamous cell carcinomas of the head and neck (SCCHN), antibodies targeting EGFR were the first protein-directed agents to show clinical benefit, and remain a standard component of clinical strategies for management of the disease. Nevertheless, many patients display either intrinsic or acquired resistance to these drugs; hence, major research goals are to better understand the underlying causes of resistance, and to develop new therapeutic strategies that boost the impact of EGFR/ErbB inhibitors. In this review, we first summarize current standard use of EGFR inhibitors in the context of SCCHN, and described new agents targeting EGFR currently moving through pre-clinical and clinical development. We then discuss how changes in other transmembrane receptors, including IGF1R, c-Met, and TGF-β, can confer resistance to EGFR-targeted inhibitors, and discuss new agents targeting these proteins. Moving downstream, we discuss critical EGFR-dependent effectors, including PLC-γ; PI3K and PTEN; SHC, GRB2, and RAS and the STAT proteins, as factors in resistance to EGFR-directed inhibitors and as alternative targets of therapeutic inhibition. We summarize alternative sources of resistance among cellular changes that target EGFR itself, through regulation of ligand availability, post-translational modification of EGFR, availability of EGFR partners for hetero-dimerization and control of EGFR intracellular trafficking for recycling versus degradation. Finally, we discuss new strategies to identify effective therapeutic combinations involving EGFR-targeted inhibitors, in the context of new system level data becoming available for analysis of individual tumors.     

Bispecific antisense oligonucleotides with multiple binding sites for the treatment of prostate tumors and their applicability to combination therapy

Antisense oligonucleotides (oligos) against transforming growth factor-alpha (TGF-alpha; MR(1)) and its binding site, the epidermal growth factor receptor (EGFR; MR(2)), have proven efficacious against PC-3 and LNCaP prostate tumors when evaluated in both in vitro and in vivo models. To enhance their activity, and also to introduce a significantly different type of multifunctional agent into this field, "bispecific" oligos were constructed containing truncated sequences (derived from MR(1) and MR(2)) recognizing both TGF-alpha and EGFR mRNA internal binding sites, located about their respective AUG initiation codons. Two bispecifics were constructed, each having complementary sequences for TGF-alpha and EGFR mRNA, but differing in their 5' to 3' tandem orientation (TGF-alpha/EGFR [MR(12)] and EGFR/TGF-alpha [MR(21)] sequences). These bispecifics were tested in an in vitro system against PC-3 and LNCaP prostate tumor cells, with comparisons made to the original monospecific oligos from which they were derived. Efficacy was also compared when administered either alone or in combination with conventional chemotherapeutic agents. The purpose of this study was: 1) to validate the concept that these newly developed bispecific oligos have antitumor activity; 2) to enhance their efficacy through combination therapy; 3) to identify differences in effectiveness dependent upon binding site orientation; 4) identification of a dominant binding site that can be used to design other bispecifics that target additional tumor regulatory pathways. When fully evaluated against PC-3 cells in a series of experiments, newly developed bispecific oligos are at least as effective as their monospecific counterparts from which they were derived, and the bispecific with the MR(21) orientation is notably more effective than the MR(1) monospecific by 64% (p = 0.014 by Student t-test and p = 0.068 by the more stringent Mann-Whitney U test). Bispecifics were more effective when administered with chemotherapeutics (producing inhibition of 52.1% and 61.2% for MR(12) and MR(21), respectively, with Cytoxan (cyclophosphamide) inhibition of 59.0% and 65.1% for MR(12) and MR(21), respectively, with Taxol (paclitaxel) and 63.0% and 69.4% for MR(12) and MR(21), respectively, with DES [diethylstilbestrol]). Increasing the oligo concentration above 6.25 microM with cyclophosphamide had no additional effect. The sequence directed against EGFR was dominant and contributed most to bispecific activity, particularly when inserted 5' to the TGF-alpha binding sequence (MR(21) orientation). Bispecific oligos are a significant advance in the design of antisense compounds and could play a role in treating prostate cancer, particularly when they are administered with traditional chemotherapeutics. The truncated portion of the MR(2) oligo used here should be included when constructing second-generation bispecifics that target proteins associated with other regulatory pathways, such as apoptosis.     

Positively charged liposomes containing tumor necrosis factor in solid tumors

The antitumor effects against solid tumors, such as Meth A sarcoma, MH-134 hepatoma and colon 26 adenocarcinoma, were examined after intratumoral administration of liposomes and Tumor Necrosis Factor (TNF) solution. The antitumor effects of liposomes against solid tumors were superior to those of TNF solution. In particular, the antitumor effect of positively charged (decyl amine) liposomes was superior to that of negatively charged liposomes and TNF solution. Further, positively charged liposomes containing a higher dose of TNF than the solution could be administered without killing the mice, because of reduced side-effects. After intratumoral (Meth A sarcoma) administration, the TNF plasma concentration was determined in order to estimate the systemic side-effects of TNF. The area under curve (AUC) after administration of positively charged liposomes containing 6 times dose of TNF was about 1/30 the AUC after the administration of TNF solution. After administration of positively charged liposomes, TNF was mainly retained locally. Positively charged liposomes exhibited a stronger antitumor effect than the solution and had a lower AUC (about 1/180) than the solution. Consequently, some solid tumors could be completely cured by positively charged liposomes, because of their increased antitumor effect and reduced toxicity.