MET and PI3K/mTOR as a Potential Combinatorial Therapeutic Target in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive disease with a poor prognosis. Studies have shown that both MET and its key downstream intracellular signaling partners, PI3K and mTOR, are overexpressed in MPM. Here we determined the combinatorial therapeutic efficacy of a new generation small molecule inhibitor of MET, ARQ 197, and dual PI3K/mTOR inhibitors NVP-BEZ235 and GDC-0980 in mesothelioma cell and mouse xenograft models. Cell viability results show that mesothelioma cell lines were sensitive to ARQ 197, NVP-BEZ235 and GDC-0980 inhibitors. The combined use of ARQ 197 with either NVP-BEZ235 or GDC-0980, was synergistic (CI<1). Significant delay in wound healing was observed with ARQ 197 (p<0.001) with no added advantage of combining it with either NVP-BEZ235 or GDC-0980. ARQ 197 alone mainly induced apoptosis (20±2.36%) that was preceded by suppression of MAPK activity, while all the three suppressed cell cycle progression. Both GDC-0980 and NVP-BEZ235 strongly inhibited activities of PI3K and mTOR as evidenced from the phosphorylation status of AKT and S6 kinase. The above observation was further substantiated by the finding that a majority of the MPM archival samples tested revealed highly active AKT. While the single use of ARQ 197 and GDC-0980 inhibited significantly the growth of MPM xenografts (p<0.05, p<0.001 respectively) in mice, the combination of the above two drugs was highly synergistic (p<0.001). Our results suggest that the combined use of ARQ 197/NVP-BEZ235 and ARQ 197/GDC-0980 is far more effective than the use of the drugs singly in suppressing MPM tumor growth and motility and therefore merit further translational studies.     

Lorvotuzumab mertansine,a CD56-targeting antibody-drug conjugate with potent antitumor activity against small cell lung cancer in human xenograft models

Lorvotuzumab mertansine (LM) is an antibody-drug conjugate composed of a humanized anti-CD56 antibody, lorvotuzumab, linked via a cleavable disulfide linker to the tubulin-binding maytansinoid DM1. CD56 is expressed on most small cell lung cancers (SCLC), providing a promising therapeutic target for treatment of this aggressive cancer, which has a poor five-year survival rate of only 5–10%. We performed immunohistochemical staining on SCLC tumor microarrays, which confirmed that CD56 is expressed at high levels on most (~74%) SCLC tumors. Conjugation of lorvotuzumab with DM1 did not alter its specific binding to cells and LM demonstrated potent target-dependent cytotoxicity against CD56-positive SCLC cells in vitro. The anti-tumor activity of LM was evaluated against SCLC xenograft models in mice, both as monotherapy and in combination with platinum/etoposide and paclitaxel/carboplatin. Dose-dependent and antigen-specific anti-tumor activity of LM monotherapy was demonstrated at doses as low as 3 mg/kg. LM was highly active in combination with standard-of-care platinum/etoposide therapies, even in relatively resistant xenograft models. LM demonstrated outstanding anti-tumor activity in combination with carboplatin/etoposide, with superior activity over chemotherapy alone when LM was used in combinations at significantly reduced doses (6-fold below the minimally efficacious dose for LM monotherapy). The combination of LM with carboplatin/paclitaxel was also highly active. This study provides the rationale for clinical evaluation of LM as a promising novel targeted therapy for SCLC, both as monotherapy and in combination with chemotherapy.     

Lorvotuzumab mertansine,a CD56-targeting antibody-drug conjugate with potent antitumor activity against small cell lung cancer in human xenograft models

Lorvotuzumab mertansine (LM) is an antibody-drug conjugate composed of a humanized anti-CD56 antibody, lorvotuzumab, linked via a cleavable disulfide linker to the tubulin-binding maytansinoid DM1. CD56 is expressed on most small cell lung cancers (SCLC), providing a promising therapeutic target for treatment of this aggressive cancer, which has a poor five-year survival rate of only 5–10%. We performed immunohistochemical staining on SCLC tumor microarrays, which confirmed that CD56 is expressed at high levels on most (~74%) SCLC tumors. Conjugation of lorvotuzumab with DM1 did not alter its specific binding to cells and LM demonstrated potent target-dependent cytotoxicity against CD56-positive SCLC cells in vitro. The anti-tumor activity of LM was evaluated against SCLC xenograft models in mice, both as monotherapy and in combination with platinum/etoposide and paclitaxel/carboplatin. Dose-dependent and antigen-specific anti-tumor activity of LM monotherapy was demonstrated at doses as low as 3 mg/kg. LM was highly active in combination with standard-of-care platinum/etoposide therapies, even in relatively resistant xenograft models. LM demonstrated outstanding anti-tumor activity in combination with carboplatin/etoposide, with superior activity over chemotherapy alone when LM was used in combinations at significantly reduced doses (6-fold below the minimally efficacious dose for LM monotherapy). The combination of LM with carboplatin/paclitaxel was also highly active. This study provides the rationale for clinical evaluation of LM as a promising novel targeted therapy for SCLC, both as monotherapy and in combination with chemotherapy.     

Furin overexpression suppresses tumor growth and predicts a better postoperative disease-free survival in hepatocellular carcinoma

Furin is a member of the pro-protein convertase family. It processes several growth regulatory proteins into their active forms, which are critical to tumor progression, metastasis, and angiogenesis. Furin over-expression could occur in liver cancer and a previous study showed that over-expression of furin promoted HepG2 cell invasion in tail vein xenograft models. However, the clinical relevance of furin expression in hepatocellular carcinoma (HCC) remained unknown. Surprisingly, in a postoperative survival analysis for HCC patients, it was found that the tumor/non-tumor (T/N) ratio of furin expression ≥ 3.5 in HCC tissues predicted a better postoperative disease-free survival (DFS) (P = 0.010; log-rank test). Furthermore, subcutaneous xenograft experiments demonstrated a significant suppression effect of tumor growth in the furin-overexpressed xenografts (Huh7-Furin) compared to the mock control. Administration of a synthetic furin inhibitor for inhibition of the pro-protein convertase activity, decanoyl-Arg-Val-Lys-Arg-chloromethylketone (decRVKR-CMK), to the Huh7-Furin xenograft bearing mice restored the repression effect of tumor growth. In contrast, administration of decRVKR-CMK to the mock Huh7 xenograft bearing mice showed no change in growth rate. In conclusion, furin overexpression inhibited HCC tumor growth in a subcutaneous xenograft model and predicted a better postoperative DFS in clinical analysis.     

Tumor disposition of pegylated liposomal CKD-602 and the reticuloendothelial system in preclinical tumor models

Liposomes, such as pegylated-liposomal CKD-602 (S-CKD602), undergo catabolism by macrophages and dendritic cells (DCs) of the reticuloendothelial system (RES). The relationship between plasma and tumor disposition of S-CKD602 and RES was evaluated in mice bearing A375 melanoma or SKOV-3 ovarian xenografts. Area under the concentration-time curves (AUCs) of liposomal encapsulated, released, and sum total (encapsulated + released) CKD-602 in plasma, tumor, and tumor extracellular fluid (ECF) were estimated. A375 and SKOV-3 tumors were stained with cd11b and cd11c antibodies as measures of macrophages and DC. The plasma disposition of S-CKD602 was similar in both xenograft models. The ratio of tumor sum total AUC to plasma sum total AUC was 1.7-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The ratio of tumor ECF AUC to tumor sum total AUC was 2-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The staining of cd11c was 4.5-fold higher in SKOV-3, compared with A375 (P?<?0.0001). The increased tumor delivery and release of CKD-602 from S-CKD602 in the ovarian xenografts, compared with the melanoma xenografts, was consistent with increased cd11c staining, suggesting that variability in the RES may affect the tumor disposition of liposomal agents.     

Tumor Xenograft Response to Redox-Active Therapies Assessed by Magnetic Resonance Imaging Using a Thiol-Bearing DOTA Complex of Gadolinium

Gd-LC6-SH is a thiol-bearing DOTA complex of gadolinium designed to bind plasma albumin at the conserved Cys(34) site. The binding of Gd-LC6-SH shows sensitivity to the presence of competing thiols. We hypothesized that Gd-LC6-SH could provide magnetic resonance imaging (MRI) enhancement that is sensitive to tumor redox state and that the prolonged retention of albumin-bound Gd-LC6-SH in vivo can be exploited to identify a saturating dose above which the shortening of MRI longitudinal relaxation time (T(1)) of tissue is insensitive to the injected gadolinium dose. In the Mia-PaCa-2 pancreatic tumor xenograft model in SCID mice, both the small-molecule Gd-DTPA-BMA and the macromolecule Galbumin MRI contrast agents produced dose-dependent decreases in tumor T(1). By contrast, the decreases in tumor T(1) provided by Gd-LC6-SH at 0.05 and 0.1 mmol/kg were not significantly different at longer times after injection. SCID mice bearing Mia-PaCa-2 or NCI-N87 tumor xenografts were treated with either the glutathione synthesis inhibitor buthionine sulfoximine or the thiol-oxidizing anticancer drug Imexon, respectively. In both models, there was a significantly greater increase in tumor R(1) (=1/T(1)) 60 minutes after injection of Gd-LC6-SH in drug-treated animals relative to saline-treated controls. In addition, Mercury Orange staining for nonprotein sulfhydryls was significantly decreased by drug treatment relative to controls in both tumor models. In summary, these studies show that thiol-bearing complexes of gadolinium such as Gd-LC6-SH can serve as redox-sensitive MRI contrast agents for detecting differences in tumor redox status and can be used to evaluate the effects of redox-active drugs.     

Targeting AKT1-E17K and the PI3K/AKT Pathway with an Allosteric AKT Inhibitor,ARQ 092

As a critical component in the PI3K/AKT/mTOR pathway, AKT has become an attractive target for therapeutic intervention. ARQ 092 and a next generation AKT inhibitor, ARQ 751 are selective, allosteric, pan-AKT and AKT1-E17K mutant inhibitors that potently inhibit phosphorylation of AKT. Biochemical and cellular analysis showed that ARQ 092 and ARQ 751 inhibited AKT activation not only by dephosphorylating the membrane-associated active form, but also by preventing the inactive form from localizing into plasma membrane. In endometrial PDX models harboring mutant AKT1-E17K and other tumor models with an activated AKT pathway, both compounds exhibited strong anti-tumor activity. Combination studies conducted in in vivo breast tumor models demonstrated that ARQ 092 enhanced tumor inhibition of a common chemotherapeutic agent (paclitaxel). In a large panel of diverse cancer cell lines, ARQ 092 and ARQ 751 inhibited proliferation across multiple tumor types but were most potent in leukemia, breast, endometrial, and colorectal cancer cell lines. Moreover, inhibition by ARQ 092 and ARQ 751 was more prevalent in cancer cell lines containing PIK3CA/PIK3R1 mutations compared to those with wt-PIK3CA/PIK3R1 or PTEN mutations. For both ARQ 092 and ARQ 751, PIK3CA/PIK3R1 and AKT1-E17K mutations can potentially be used as predictive biomarkers for patient selection in clinical studies.     

Conventional Chemotherapy and Oncogenic Pathway Targeting in Ovarian Carcinosarcoma Using a Patient-Derived Tumorgraft

Ovarian carcinosarcoma is a rare subtype of ovarian cancer with poor clinical outcomes. The low incidence of this disease makes accrual to large clinical trials challenging. However, studies have shown that treatment responses in patient-derived xenograft (PDX) models correlate with matched-patient responses in the clinic, supporting their use for preclinical testing of standard and novel therapies. An ovarian carcinosarcoma PDX is presented herein and showed resistance to carboplatin and paclitaxel (similar to the patient) but exhibited significant sensitivity to ifosfamide and paclitaxel. The PDX demonstrated overexpression of EGFR mRNA and gene amplification by array comparative genomic hybridization (log2 ratio 0.399). EGFR phosphorylation was also detected. Angiogensis and insulin-like growth factor pathways were also implicated by overexpression of VEGFC and IRS1. In order to improve response to chemotherapy, the PDX was treated with carboplatin/paclitaxel with or without a pan-HER and VEGF inhibitor (BMS-690514) but there was no tumor growth inhibition or improved animal survival, which may be explained by a KRAS mutation. Resistance was also observed when the IGF-1R inhibitor BMS-754807 was combined with carboplatin/paclitaxel. Because poly (ADP-ribose) polymerase inhibitors have activity in ovarian cancer patients, with and without BRCA mutations, ABT-888 was also tested but found to have no activity. Pathogenic mutations were also detected in TP53 and PIK3CA. In conclusion, ifosfamide/paclitaxel was superior to carboplatin/paclitaxel in this ovarian carcinosarcoma PDX and gene overexpression or amplification alone was not sufficient to predict response to targeted therapy. Better predictive markers of response are needed.     

Assessment of a novel VEGF targeted agent using patient-derived tumor tissue xenograft models of colon carcinoma with lymphatic and hepatic metastases

The lack of appropriate tumor models of primary tumors and corresponding metastases that can reliably predict for response to anticancer agents remains a major deficiency in the clinical practice of cancer therapy. It was the aim of our study to establish patient-derived tumor tissue (PDTT) xenograft models of colon carcinoma with lymphatic and hepatic metastases useful for testing of novel molecularly targeted agents. PDTT of primary colon carcinoma, lymphatic and hepatic metastases were used to create xenograft models. Hematoxylin and eosin staining, immunohistochemical staining, genome-wide gene expression analysis, pyrosequencing, qRT-PCR, and western blotting were used to determine the biological stability of the xenografts during serial transplantation compared with the original tumor tissues. Early passages of the PDTT xenograft models of primary colon carcinoma, lymphatic and hepatic metastases revealed a high degree of similarity with the original clinical tumor samples with regard to histology, immunohistochemistry, genes expression, and mutation status as well as mRNA expression. After we have ascertained that these xenografts models retained similar histopathological features and molecular signatures as the original tumors, drug sensitivities of the xenografts to a novel VEGF targeted agent, FP3 was evaluated. In this study, PDTT xenograft models of colon carcinoma with lymphatic and hepatic metastasis have been successfully established. They provide appropriate models for testing of novel molecularly targeted agents.     

5-烯丙基-7-二氟亚甲基白杨素对人肺癌A549细胞裸鼠移植瘤生长的影响

目的研究5-烯丙基-7-二氟亚甲基白杨素（ADFMChR）对人肺癌A549细胞裸鼠移植瘤生长的影响。方法建立人肺癌A549细胞裸鼠移植瘤模型,测定荷人肺癌裸鼠移植瘤的大小和重量,应用免疫组化SP法检测移植瘤组织中PCNA、VEGF、CD31的表达。结果ADFMChR对肺癌移植瘤生长有显著抑制作用（P〈0.01）,5.0、10.0、20.0 mg/（kg.bw）的ADFMChR对移植瘤的瘤重抑制率分别为42.98%,82.31%和89.91%。免疫组化检测结果表明：ADFMChR具有抑制肺腺癌裸鼠移植瘤细胞PCNA、VEGF及CD31蛋白表达作用。结论ADFMChR抑制肺腺癌裸鼠移植瘤的生长作用与其抑制移植瘤细胞PCNA、VEGF以及CD31的蛋白表达相关。     

Pharmacokinetic modeling of an induction regimen for in vivo combined testing of novel drugs against pediatric acute lymphoblastic leukemia xenografts

Current regimens for induction therapy of pediatric acute lymphoblastic leukemia (ALL), or for re-induction post relapse, use a combination of vincristine (VCR), a glucocorticoid, and L-asparaginase (ASP) with or without an anthracycline. With cure rates now approximately 80%, robust pre-clinical models are necessary to prioritize active new drugs for clinical trials in relapsed/refractory patients, and the ability of these models to predict synergy/antagonism with established therapy is an essential attribute. In this study, we report optimization of an induction-type regimen by combining VCR, dexamethasone (DEX) and ASP (VXL) against ALL xenograft models established from patient biopsies in immune-deficient mice. We demonstrate that the VXL combination was synergistic in vitro against leukemia cell lines as well as in vivo against ALL xenografts. In vivo, VXL treatment caused delays in progression of individual xenografts ranging from 22 to >146 days. The median progression delay of xenografts derived from long-term surviving patients was 2-fold greater than that of xenografts derived from patients who died of their disease. Pharmacokinetic analysis revealed that systemic DEX exposure in mice increased 2-fold when administered in combination with VCR and ASP, consistent with clinical findings, which may contribute to the observed synergy between the 3 drugs. Finally, as proof-of-principle we tested the in vivo efficacy of combining VXL with either the Bcl-2/Bcl-xL/Bcl-w inhibitor, ABT-737, or arsenic trioxide to provide evidence of a robust in vivo platform to prioritize new drugs for clinical trials in children with relapsed/refractory ALL.     

Superior Therapeutic Efficacy of Nanoparticle Albumin Bound Paclitaxel Over Cremophor-Bound Paclitaxel in Experimental Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) is the fastest growing cancer in the western world and the overall 5 year survival rate of EAC is below 20%. Most patients with EAC present with locally advanced or widespread metastatic disease, where current treatment is largely ineffective. Therefore, new therapeutic approaches are urgently needed. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is a novel albumin-stabilized, cremophor-free and water soluble nanoparticle formulation of paclitaxel, and the potential role of nab-paclitaxel has not been tested yet in experimental EAC. Here we tested the antiproliferative and antitumor efficacy with survival advantage of nab-paclitaxel as monotherapy and in combinations in in-vitro, and in murine subcutaneous xenograft and peritoneal metastatic survival models of human EAC. Nab-paclitaxel significantly inhibited in-vitro cell proliferation with higher in-vivo antitumour efficacy and survival benefit compared to paclitaxel or carboplatin treatments both in mono- and combination therapies. Nab-paclitaxel treatment increased expression of mitotic-spindle associated phospho-stathmin, decreased expression of proliferative markers and enhanced apoptosis. This study demonstrates that nab-paclitaxel had stronger antiproliferative and antitumor activity in experimental EAC than the current standard chemotherapeutic agents which supports the rationale for its clinical use in EAC.     

Establishment of human tumor xenografts in immunodeficient mice

Heterotransplantation of human cancer cells or tumor biopsies into immunodeficient rodents (xenograft models) has, for the past two decades, constituted the major preclinical screen for the development of novel cancer therapeutics. Despite limitations, these models have identified clinically efficacious agents, and remain the 'workhorse' of the pharmaceutical industry. However, if therapeutic approaches to treating tumors according to their molecular characteristics are to be achieved, additional new models of human cancer will be required to represent the genetic diversity that exists within tumor histologies. This protocol details a method for establishing xenografts from primary solid-tumor isolates or cells grown in culture. The procedure relies on immunodeficient mice to provide a host for the establishment of human xenografts. The procedure can be completed in 1-2 h with results being obtained in 1-4 months.     

Evaluation of the Antitumor Activity of Dacomitinib in Models of Human Bladder Cancer

Members of the human epidermal growth factor receptor (HER) family play a significant role in bladder cancer progression and may underlie the development of chemotherapy resistance. Dacomitinib is an irreversible tyrosine kinase inhibitor with structural specificity for the catalytic domains of epidermal growth factor receptor (EGFR), HER2 and HER4 that has exhibited vigorous efficacy against other solid tumors. We evaluated the antitumor activity of dacomitinib in human bladder cancer cell lines expressing varying levels of HER family receptors. These cell lines also were established as bladder cancer xenografts in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice to assess dacomitinib activity in vivo. Significant cytotoxic and cytostatic effects were noted in cells expressing elevated levels of the dacomitinib target receptors with apoptosis and cell cycle arrest being the predominant mechanisms of antitumor activity. Cells expressing lower levels of HER receptors were much less sensitive to dacomitinib. Interestingly, dacomitinib was more active than either trastuzumab or cetuximab in vitro, and exhibited increased growth inhibition of bladder tumor xenografts compared with lapatinib. Pharmacodynamic effects of dacomitinib included decreased E-cadherin (E-cad) expression, reduction of EGFR and extracellular signal-regulated kinase (ERK) phosphorylation and reduced mitotic count. Dacomitinib also inhibited tumor growth in a chemotherapy-resistant xenograft and, when combined with chemotherapy in a sensitive xenograft, exhibited superior antitumor effects compared with individual treatments. Evaluation in xenograft-bearing mice revealed that this combination was broadly feasible and well tolerated. In conclusion, dacomitinib exhibited pronounced activity both as a single agent and when combined with chemotherapy in human bladder cancer models. Further investigation of dacomitinib in the preclinical and clinical trial settings is being pursued.     

Combined Delivery of Paclitaxel and Tanespimycin via Micellar Nanocarriers: Pharmacokinetics,Efficacy and Metabolomic Analysis

Background

Despite the promising anticancer efficacy observed in preclinical studies, paclitaxel and tanespimycin (17-AAG) combination therapy has yielded meager responses in a phase I clinical trial. One serious problem associated with paclitaxel/17-AAG combination therapy is the employment of large quantities of toxic organic surfactants and solvents for drug solubilization. The goal of this study was to evaluate a micellar formulation for the concurrent delivery of paclitaxel and 17-AAG in vivo.

Methodology/Principal Findings

Paclitaxel/17-AAG-loaded micelles were assessed in mice bearing human ovarian tumor xenografts. Compared with the free drugs at equivalent doses, intravenous administration of paclitaxel/17-AAG-loaded micelles led to 3.5- and 1.7-fold increase in the tumor concentrations of paclitaxel and 17-AAG, respectively, without significant altering drug levels in normal organs. The enhanced tumor accumulation of the micellar drugs was further confirmed by the whole-body near infrared imaging using indocyanine green-labeled micelles. Subsequently, the anticancer efficacy of paclitaxel/17-AAG-loaded micelles was examined in comparison with the free drugs (weekly 20 mg/kg paclitaxel, twice-weekly 37.5 mg/kg 17-AAG). We found that paclitaxel/17-AAG-loaded micelles caused near-complete arrest of tumor growth, whereas the free drug-treated tumors experienced rapid growth shortly after the 3-week treatment period ended. Furthermore, comparative metabolomic profiling by proton nuclear magnetic resonance revealed significant decrease in glucose, lactate and alanine with simultaneous increase in glutamine, glutamate, aspartate, choline, creatine and acetate levels in the tumors of mice treated with paclitaxel/17-AAG-loaded micelles.

Conclusions/Significance

We have demonstrated in the current wok a safe and efficacious nano-sized formulation for the combined delivery of paclitaxel and 17-AAG, and uncovered unique metabolomic signatures in the tumor that correlate with the favorable therapeutic response to paclitaxel/17-AAG combination therapy.     

K-RAS Mutant Pancreatic Tumors Show Higher Sensitivity to MEK than to PI3K Inhibition In Vivo

Activating K-RAS mutations occur at a frequency of 90% in pancreatic cancer, and to date no therapies exist targeting this oncogene. K-RAS signals via downstream effector pathways such as the MAPK and the PI3K signaling pathways, and much effort has been focused on developing drugs targeting components of these pathways. To better understand the requirements for K-RAS and its downstream signaling pathways MAPK and PI3K in pancreatic tumor maintenance, we established an inducible K-RAS knock down system that allowed us to ablate K-RAS in established tumors. Knock down of K-RAS resulted in impaired tumor growth in all pancreatic xenograft models tested, demonstrating that K-RAS expression is indeed required for tumor maintenance of K-RAS mutant pancreatic tumors. We further examined signaling downstream of K-RAS, and detected a robust reduction of pERK levels upon K-RAS knock down. In contrast, no effect on pAKT levels could be observed due to almost undetectable basal expression levels. To investigate the requirement of the MAPK and the PI3K pathways on tumor maintenance, three selected pancreatic xenograft models were tested for their response to MEK or PI3K inhibition. Tumors of all three models regressed upon MEK inhibition, but showed less pronounced response to PI3K inhibition. The effect of MEK inhibition on pancreatic xenografts could be enhanced further by combined application of a PI3K inhibitor. These data provide further rationale for testing combinations of MEK and PI3K inhibitors in clinical trials comprising a patient population with pancreatic cancer harboring mutations in K-RAS.     

Pazopanib,a Receptor Tyrosine Kinase Inhibitor,Suppresses Tumor Growth through Angiogenesis in Dedifferentiated Liposarcoma Xenograft Models

INTRODUCTION: The rarity of dedifferentiated liposarcoma (DDLPS) and the lack of experimental DDLPS models limit the development of novel therapeutic strategies. Pazopanib (PAZ) is a tyrosine kinase inhibitor that is approved for the treatment of non-adipocytic advanced soft tissue sarcoma. The activity of this agent has not yet been properly explored in preclinical liposarcoma models nor in a randomized phase Ш clinical trial in this entity. The aim of the present study was to investigate whether PAZ had antitumor activity in DDLPS models in vivo. MATERIAL AND METHODS: We established two patient-derived DDLPS xenograft models (UZLX-STS3 and UZLX-STS5) through implantation of tumor material from sarcoma patients in athymic nude NMRI mice. An animal model of the SW872 liposarcoma cell line was also used. To investigate the efficacy of PAZ in vivo, mice bearing tumors were treated for 2 weeks with sterile water, doxorubicin (1.2 mg/kg, intraperitoneally, twice per week), PAZ [40 mg/kg, orally (p.o.), twice per day], or PAZ plus doxorubicin (same schedules as for single treatments). RESULTS: Patient-derived xenografts retained the histologic and molecular features of DDLPS. PAZ significantly delayed tumor growth by decreasing proliferation and inhibited angiogenesis in all models tested. Combining the angiogenesis inhibitor with an anthracycline did not show superior efficacy. CONCLUSION: These results suggest that PAZ has potential antitumor activity in DDLPS primarily through antiangiogenic effects and therefore should be explored in clinical trials.     

Design, synthesis, and biological evaluation of novel water-soluble N-mustards as potential anticancer agents

A series of novel water-soluble N-mustard-benzene conjugates bearing a urea linker were synthesized. The benzene moiety contains various hydrophilic side chains are linked to the meta- or para-position of the urea linker via a carboxamide or an ether linkage. The preliminary antitumor studies revealed that these agents exhibited potent cytotoxicity in vitro and therapeutic efficacy against human tumor xenografts in vivo. Remarkably, complete tumor remission in nude mice bearing human breast carcinoma MX-1 xenograft and significant suppression against prostate adenocarcinoma PC3 xenograft were achieved by treating with compound 9aa′ at the maximum tolerable dose with relatively low toxicity. We also demonstrate that the newly synthesized compounds are able to induce DNA cross-linking through alkaline agarose gel shift assay. A pharmacokinetic profile of the representative 9aa′ in rats was also investigated. The current studies suggest that this agent is a promising candidate for preclinical studies.     

Antitumor activity of the novel human cytokine AIMP1 in an in vivo tumor model

Although AIMP1 (previously known as p43) is one of three auxiliary proteins bound to a macromolecular aminoacyl tRNA complex, it is also secreted as a cytokine controlling both angiogenesis and immune responses. Here we show that systemically administered purified recombinant human AIMP1 had anti-tumor activity in mouse xenograft models. In Meth A-bearing Balb/c mice, tumor volume increased about 28 fold in the vehicle treatment group, while an increase of about 16.7 fold was observed in the AIMP1-treated group. We also evaluated the anti-tumor activity of AIMP1 in combination with a sub-clinical dose of the cytotoxic anti-tumor drug, paclitaxel. The growth of NUGC-3 human stomach cancer cells was suppressed by 84% and 94% by the combinations of 5 mg/kg paclitaxel + 25 mg/kg AIMP1 (p = 0.03), and 5 mg/kg paclitaxel + 50 mg/kg AIMP1 (p = 0.02), respectively, while 5 mg/kg paclitaxel alone suppressed growth by only 54% (p = 0.02). A similar cooperative effect of AIMP1 and paclitaxel was observed in a lung cancer xenograft model. These results suggest that AIMP1 may be useful as a novel anti-tumor agent.     

Radiolabeled anti-claudin 4 and anti-prostate stem cell antigen: initial imaging in experimental models of pancreatic cancer

Global expression profiling of pancreatic cancers has identified two cell surface molecules, claudin 4 and prostate stem cell antigen (PSCA), as being overexpressed in the vast majority of cases. Two antibodies, anti-claudin 4 and anti-PSCA, were radiolabeled with iodine 125 ((125)I) for imaging pancreatic cancer xenografts in mice using gamma scintigraphy and single-photon emission computed tomography-computed tomography (SPECT-CT). Immunofluorescence staining of intact and permeabilized Colo357 human pancreatic cancer cells showed strong extracellular staining by both anti-PSCA and anti-claudin 4. Biodistribution studies in claudin 4 and PSCA-expressing Colo357 and PANC-1 subcutaneous xenograft models in mice showed that [(125)I]anti-claudin 4 tumor to muscle ratio uptake was 4.3 in Colo357 at 6 days postinjection and 6.3 in PANC-1 xenografts at 4 days postinjection. Biodistribution of [(125)I]anti-PSCA showed tumor to muscle ratio uptake of 4.9 in Colo357 at 6 days postinjection. Planar gamma scintigraphic imaging in Colo357 xenograft-bearing mice showed clear tumor uptake of [(125)I]anti-claudin 4 by 24 hours postinjection and by 48 hours postinjection for [(125)I]anti-PSCA. SPECT-CT imaging with [(125)I]anti-claudin 4 and [(125)I]anti-PSCA in an L3.6PL orthotopic xenograft model showed strong tumor and spleen uptake at 5 days postinjection. Both anti-claudin 4 and anti-PSCA demonstrate promise as radiodiagnostic and possibly radiotherapeutic agents for human pancreatic cancers.