Showed Tumor Growth Inhibition Research Articles

Electroporation driven delivery of both an IL-12 expressing plasmid and cisplatin synergizes to inhibit B16 melanoma tumor growth through an NK cell mediated tumor killing mechanism

Combined therapy using chemotherapeutic drugs and immunotherapeutics offers some promise for treating patients with cancer. In this study, we evaluated whether cisplatin delivered by intratumoral (IT)-electroporation (EP) might enhance antitumor activity against established B16 melanoma and whether further addition of intramuscular (IM)-EP of IL-12 cDNA to IT-EP of cisplatin might augment antitumor therapeutic activity, with a focus on the underlining antitumor mechanism(s). When tumor (7 mm)-bearing animals were treated locally with cisplatin by IT-EP, they showed tumor growth inhibition significantly more than those without IT-EP. Moreover, IL-12 cDNA delivered by IM-EP was also able to inhibit tumor growth significantly more than control vector delivery. This tumor growth inhibition was mediated by NK cells, but not CD4+ T or CD8+ T cells, as determined by immune cell subset depletion and IFN-γ induction. Moreover, concurrent therapy using IT-EP of cisplatin plus IM-EP of IL-12 cDNA displayed antitumor therapeutic synergy. This therapeutic synergy appeared to be mediated by increased sensitivity of cisplatin-treated tumors to NK cell-mediated tumor killing. Taken together, these data support that cisplatin delivery by IT-EP plus IL-12 gene delivery by IM-EP are more effective at inducing antitumor therapeutic responses through increased sensitivity of cisplatin-treated tumors to NK cell-mediated tumor killing. This combined approach might have some implication for treating melanoma in patients.

In vivo photodynamic therapy using upconversion nanoparticles as remote-controlled nanotransducers

Conventional photodynamic therapy (PDT) is limited by the penetration depth of visible light needed for its activation. Here we used mesoporous-silica-coated upconversion fluorescent nanoparticles (UCNs) as a nanotransducer to convert deeply penetrating near-infrared light to visible wavelengths and a carrier of photosensitizers. We also used the multicolor-emission capability of the UCNs at a single excitation wavelength for simultaneous activation of two photosensitizers for enhanced PDT. We showed a greater PDT efficacy with the dual-photosensitizer approach compared to approaches using a single photosensitizer, as determined by enhanced generation of singlet oxygen and reduced cell viability. In vivo studies also showed tumor growth inhibition in PDT-treated mice by direct injection of UCNs into melanoma tumors or intravenous injection of UCNs conjugated with a tumor-targeting agent into tumor-bearing mice. As the first demonstration, to the best of our knowledge, of the photosensitizer-loaded UCN as an in vivo-targeted PDT agent, this finding may serve as a platform for future noninvasive deep-cancer therapy.

Rapid identification of ETP-46992, orally bioavailable PI3K inhibitor, selective versus mTOR

Phosphoinositide-3-kinases (PI3K) are a family of lipid kinases mediating numerous cell processes such as proliferation, migration and differentiation. PI3K is an important target for cancer therapeutics due to the deregulation of this signaling pathway in a wide variety of human cancers. Herein, we describe the rapid identification of ETP-46992, within 2-aminocarbonyl imidazo [1,2-a] pyrazine series, with suitable pharmacokinetic (PK) properties that allows the establishment of mechanism of action and efficacy in vivo studies. ETP-46992 showed tumor growth inhibition in a GEMM mouse tumor model driven by a K-RasG12V oncogenic mutation and in tumor xenograft models with PI3K pathway deregulated (BT474).

Abstract 2726: Efficacy and candidate biomarker evaluation for the anti-mesothelin antibody drug conjugate (ADC) BAY 94-9343, mesothelin-ADC in mesothelin-positive preclinical xenograft models

Abstract BAY 94-9343 is a novel antibody drug conjugate consisting of a fully human monoclonal antibody directed against mesothelin conjugated with the maytansinoid derivative DM4 by a linker containing a disulfide bridge (SPDB) and currently in Phase I clinical testing. Mesothelin is expressed in a range of tumor types, such as mesothelioma, ovarian cancer, pancreatic cancer and lung cancer. Membrane-anchored forms may play a role in cellular adhesion and metastasis. Here we report on the correlation of tumor mesothelin antigen expression levels, as determined by a newly developed mesothelin IHC staining protocol, and the efficacy of BAY 94-9343 in 13 preclinical tumor models. Further, mesothelin levels in xenograft tumors were compared to those in clinical samples of human tumors. Efficacy of BAY 94-9343 in tumor models with high mesothelin expression levels were generally higher compared to models with low mesothelin expression. OVCAR6677, OVCAR6668 and MIAPaCa-meso models characterized by high expression of mesothelin showed 90-100 % tumor growth inhibition, when treated with 2.5 mg/kg BAY 94-9343. PAXF736 and PAXF1881, tumor models with no mesothelin expression, did not show tumor growth inhibition at 2.5 mg/kg mesothelin-ADC, but responded to higher doses. Analysis of mesothelin expression by IHC using human tumor samples (mesothelioma, ovarian and pancreatic cancer) demonstrated that tumor cell mesothelin expression varied both within and between tumor types. IHC scoring revealed that 92% of mesothelioma tumors, 80% of ovarian tumors, and 63% of pancreatic cancer tumors assayed were mesothelin positive. Mesothelin expression was stable when comparing primary ovarian cancers with relapsing tumor tissue from the same patient. Maximum mesothelin expression in ovarian cancer is at least 400,000 antigenic sites per cell determined by Quantibrite technology. In preclinical models analysis of serum mesothelin extracellular domain (ECD) by ELISA revealed an initial rise in serum mesothelin ECD as early as 1 days after 10 mg/kg BAY 94-9343 followed by a decrease to below-baseline levels. Increased levels of the apoptosis marker CK18 were observed following BAY 94-9343 administration. Changes in serum mesothelin ECD levels as well as CK18 will be explored as an early pharmacodynamic (PD) response markers in clinical trials for BAY 94-9343. In summary, these results demonstrate that targeted delivery of DM4 resulted in higher efficacy of BAY 94-9343 in tumor models with high mesothelin expression. Responsive xenograft models were representative of clinical samples with respect to mesothelin expression scored by IHC. Quantification of mesothelin by IHC is a candidate stratification biomarker for the antibody drug conjugate BAY 94-9343 currently in Phase I testing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2726. doi:1538-7445.AM2012-2726

Abstract 3710: Preclinical dose scheduling studies of LOR-253, a novel anticancer drug, in combination with chemotherapeutics in lung and colon cancers

Abstract LOR-253 is an anticancer small molecule that is currently in a Phase I clinical study in patients with advanced or metastatic solid tumors. LOR-253 has a novel anticancer mechanism based on chelation of intracellular labile zinc, leading to inhibition of angiogenesis as well as G1/S cell cycle arrest due to induction of the tumor suppressor Kruppel-like factor 4 (KLF4). In preclinical studies, LOR-253 has shown potent antitumor activity against several cancers, including non-small cell lung cancer (NSCLC) and colon cancer, without significant toxicity. To support the clinical development of LOR-253 in combination with chemotherapeutics, we investigated the effect of dose scheduling of LOR-253 plus chemotherapy agents on anticancer activity in NSCLC (H226) and colon cancer (SW620) cell lines. Treatment of H226 cells in vitro with docetaxel, paclitaxel, or cisplatin for two days followed by increasing doses of LOR-253 resulted in significantly higher anti-proliferative activity than either agent alone. Assessment of drug interactions by determination of the combination index (D) (Berenbaum MC, Adv Cancer Res., 1981; 35:269-335) showed that the anticancer activities of the combination of LOR-253 with these chemotherapy agents were synergistic (D < 1). In studies with LOR-253 and docetaxel, synergistic anticancer activity against H226 was maintained with either concurrent or sequential treatments of each agent. Anticancer synergy was also seen in SW620 cells treated with LOR-253 in combination with oxaliplatin, CPT-11, or Fluorouracil. The effects of dose scheduling on activity of LOR-253 and docetaxel in vivo was also examined. Nude mice with H226 tumor xenografts were treated with repeat cycles of docetaxel once per week, followed two days later by treatment with LOR-253 for three consecutive days. Docetaxel was administered at an experimentally-determined ED50 dose level (defined as the effective dose at which 50% of mice showed tumor growth inhibition), while LOR-253 was given at its maximum efficacious dose in this model (10 mg/kg) or sub-optimal dose (5 mg/kg). Sequential administration of docetaxel followed by LOR-253 showed significant antitumor activity when docetaxel was given at either ED50 or sub-ED50 doses plus 10 mg/kg of LOR-253, compared to either agent alone given at the same dose, or with concurrent administration of LOR-253 and docetaxel at these dose levels. Preliminary results also show significant antitumor activity of LOR-253 plus docetaxel against H226 tumors in mice treated with repeat cycles of the reverse order of these treatments (LOR-253 for three days, followed by docetaxel 1X/week). In summary, dose scheduling studies with LOR-253 plus chemotherapy drugs demonstrate strong anticancer activities in NSCLC and colon cancer, providing support for the design of LOR-253 combination strategies for treatment of these cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3710. doi:1538-7445.AM2012-3710

Abstract 3737: The PI3K/mTOR inhibitor PWT33597 regresses 786-0 renal xenografts

Abstract PWT33597 is a balanced dual inhibitor of phosphatidylinositol 3-kinase alpha (PI3K alpha) and mTOR, currently in clinical development. Inhibition of signaling downstream of PI3K and mTOR by PWT33597 has been demonstrated, and PWT33597 is strongly efficacious in multiple xenograft models tested to date with different PIK3CA and PTEN genotypes. Inhibitors of mTORC1 (rapalogs) are approved for treatment of advanced renal cell carcinoma (RCC), but their effect is restricted to a subset of patients, and is not sustained. Inhibitors of VEGFR signaling such as sorafenib and sunitinib have also demonstrated clinical activity in RCC and are approved in this indication. Based on the proven role of rapalogs in RCC, we tested PWT33597 in a renal xenograft model with the hypothesis that inhibition of both mTORC1 and mTORC2, as well as PI3K, may offer increased efficacy by direct targeting of multiple signaling nodes including VEGFR signaling. Dual inhibition would also be expected to decrease release of negative feedback loops triggered by either mTOR or PI3K inhibition alone. PWT33597 was tested in 786-0 (VHL -/-, PTEN -/-) xenografts in comparison to rapamycin (mTORC1 inhibitor), and sorafenib (VEGFR/RAF inhibitor). While sorafenib and rapamycin showed tumor growth inhibition (TGI), the maximal effect with sorafenib was 64% TGI, and rapamycin had a largely cytostatic effect. The overall efficacy observed with PWT33597 was superior, with 93% TGI observed. PWT33597 was also tested in comparison to a pan-PI3K inhibitor (GDC-0941, 49% TGI) and demonstrated superior efficacy. Immunohistochemical analysis of tumors for cleaved caspase 3 (CC3) as an indicator of apoptosis showed that a single dose of PWT33597 induced a several fold increase in CC3 staining, and this effect was also apparent after 18 days of dosing. Based on these results we tested the ability of PWT33597 to regress large 786-0 tumors (approx. 500 mm3), and a rapid decrease in tumor size was observed in 100% of animals. Additional cellular and xenograft studies in RCC models are ongoing to further define the mechanism of action of PWT33597, and will be presented. Taken together, these data provide rationale for testing PWT33597 in patients with RCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3737. doi:1538-7445.AM2012-3737

Prostate‐Cancer‐Targeted N‐(2‐Hydroxypropyl)methacrylamide Copolymer/Docetaxel Conjugates

Biodistribution, pharmacokinetics, and efficacy of prostate-cancer-targeted HPMA copolymer/DTX conjugates are evaluated in nude mice bearing prostate cancer C4-2 xenografts. PSMA-specific monoclonal antibodies 3F/11 are used as the targeting moiety. Control conjugates tumor accumulation to total background organs (heart, lung, kidney, liver, spleen and blood) accumulation increase substantially with time for the targeted conjugate, and the ratio at 48 h is 7-fold higher than that at 6 h. Preliminary evaluation of the efficacy of the conjugates in vivo show tumor growth inhibition for all HPMA copolymer/DTX conjugates.

Novel pyrazolo[1,5-a]pyridines as p110α-selective PI3 kinase inhibitors: Exploring the benzenesulfonohydrazide SAR

Structure–activity relationship studies of the pyrazolo[1,5-a]pyridine class of PI3 kinase inhibitors show that substitution off the hydrazone nitrogen and replacement of the sulfonyl both gave a loss of p110α selectivity, with the exception of an N-hydroxyethyl analogue. Limited substitutions were tolerated around the phenyl ring; in particular the 2,5-substitution pattern was important for PI3 kinase activity. The N-hydroxyethyl compound also showed good inhibition of cell proliferation and inhibition of phosphorylation of Akt/PKB, a downstream marker of PI3 kinase activity. It had suitable pharmacokinetics for evaluation in vivo, and showed tumour growth inhibition in two human tumour cell lines in xenograft studies. This work has provided suggestions for the design of more soluble analogues.

Comparison of Pretargeted and Conventional CC49 Radioimmunotherapy Using 149Pm, 166Ho, and 177Lu

The therapeutic efficacies of radiolabeled biotin, pretargeted by monoclonal antibody (mAb)-streptavidin fusion protein CC49 scFvSA, were compared to those of radiolabeled mAb CC49, using the three radiolanthanides in an animal model of human colon cancer. The purpose of the present study was to compare antibody pretargeting to conventional radioimmunotherapy using (149)Pm, (166)Ho, or (177)Lu. Nude mice bearing LS174T colon tumors were injected sequentially with CC49 scFvSA, the blood clearing agent biotin-GalNAc(16), and (149)Pm-, (166)Ho-, or (177)Lu-DOTA-biotin. Tumor-bearing mice were alternatively administered (149)Pm-, (166)Ho-, or (177)Lu-MeO-DOTA-CC49. Therapy with pretargeted (149)Pm-,(166)Ho-, and (177)Lu-DOTA-biotin increased the median time of progression to a 1 g tumor to 50, 41, and 50 days post-treatment, respectively. Therapy with (149)Pm-,(166)Ho-, and (177)Lu-MeO-DOTA-CC49 increased the median time to progression to 53, 24, and 67 days post-treatment, respectively. In contrast, saline controls showed a median time to progression of 13 days postinjection. Treatment with pretargeted (149)Pm-, (166)Ho-, and (177)Lu-biotin or (149)Pm-, (166)Ho-, and (177)Lu-CC49 increased tumor doubling time to 18-36 days, compared to 3 days for saline controls. Among treated mice, 23% survived >84 days post-therapy, and 11% survived 6 months, but controls survived <29 days. Long-term survivors showed tumor growth inhibition or partial regression, extensive necrosis in residual masses, and no evidence of nontarget tissue toxicity at necropsy. Both pretargeted and conventional RIT demonstrated considerable efficacy in an extremely aggressive animal model of cancer. Our results identified (177)Lu as an optimal radiolanthanide for future evaluation of these agents in toxicity and multiple-dose therapy studies.

A novel hydrogen bonded bimetallic supramolecular coordination polymer {[SnMe3(bpe)][Ag(CN)2]·2H2O} as anticancer drug

The reaction of Me3SnCl, K3[Ag(CN)4] and 1,2-bis(4-pyridyl)ethane (bpe) in water/CH3CN solution at room temperature affords the novel bimetallic supramolecular coordination polymer (SCP) {[SnMe3(bpe)] [Ag(CN)2]·2H2O}n, 1. The structure of 1 consists of cationic {–Sn(Me3)–bpe–}+ chains that are neutralized by [Ag(CN)2]− anions. The dicyanoargentate(I) anions present discrete uncoordinated fragments between the cationic chains. The water molecules bind the cationic chains and the anions forming 3D-supramolecular structure through hydrogen bonds. 1 exhibits strong fluorescence in the solid state at room temperature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the in vitro antitumor effects of the SCP 1 on human breast cancer cell line, T-47D. Cell cycle analysis revealed that the SCP 1 induced apoptosis in T-47D breast cancer cell line. Moreover, in vivo, the SCP 1 showed tumor growth inhibition in rat model that developed mammary carcinoma by 44.8% compared to the vehicle treated control. Thus, the SCP 1 exhibits specific in vivo and in vitro antitumor effects.

Abstract 1761: Anti-tumor activity of trastuzumab-DM1 in combination with pertuzumab in a gastric cancer model

Abstract Objective: Anti-HER2 therapy is considered to be important for gastric cancer as well as breast cancer. In a previous study, we showed the combinational efficacy of trastuzumab and pertuzumab (an anti-HER2 antibody which binds a different HER2 domain from trastuzumab) in HER2-positive gastric cancer models (AACR, 2010). In the present study, we investigated the usefulness of a HER2 antibody-cytotoxic drug conjugate, trastuzumab-DM1 (T-DM1) as monotherapy and in combination with pertuzumab for HER2-positive gastric cancer as a novel therapy. Methods: A HER2 over-expressing human gastric cancer, NCI-N87 mouse xenograft model was used for examining the efficacy. T-DM1 was administered intravenously once every 3 weeks. Pertuzumab was administered intra-peritoneally once a week. Tumor growth inhibition (TGI) after 6 weeks of treatment was determined from tumor volume measurements. Apoptosis activity was measured with the activity of caspase 3/7. To measure ADCC activity, a real-time cell analyzer was used. Results: T-DM1 (1.25, 2.5, 5, 10, 20, 40 or 80 mg/kg) as monotherapy showed tumor growth inhibition dose-dependently in the NCI-N87 model. The maximum effective dose was 10 mg/kg and TGI on day 42 after treatment started was 113%. T-DM1 (5 mg/kg) in combination with pertuzumab (40 mg/kg) in the NCI-N87 model showed significantly potent anti-tumor activity with a TGI of 113%. Both T-DM1 and pertuzumab as monotherapies showed significant anti-tumor activity, their TGI were 79% and 47%, respectively. To examine the mechanism of action of the combination of T-DM1 and pertuzumab, we analyzed apoptosis of NCI-N87 cells after treatment with T-DM1, pertuzumab or both under stimulation of EGF or heregulin. 24 h after treatment, the combination group had significantly enhanced caspase 3/7 activity compared with the monotherapy groups. We also examined ADCC activity of these agents. Both T-DM1 and pertuzumab showed ADCC activity and that activity was enhanced by the combination. Conclusion: In this study, we showed that T-DM1 as monotherapy has significant anti-tumor activity in a mice model of HER2-positive gastric cancer. Furthermore, combining T-DM1 with pertuzumab significantly enhanced the anti-tumor activity compared with the efficacy of each agent used in monotherapy. The mechanism of this combination might be the potentiation of apoptosis induction and ADCC activity. The present study suggests that T-DM1 as monotherapy and in combination with pertuzumab would provide benefit for patients with HER2-positive gastric cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1761. doi:10.1158/1538-7445.AM2011-1761

In vitro and in vivo antiproliferative activity of Calotropis procera stem extracts

The cytotoxic potential of stem organic extracts from Calotropis procera (Asclepiadaceae) was firstly evaluated against cancer cell lines by MTT assay. Subsequently, samples considered cytotoxic were tested for antimitotic activity on sea urchin egg development and for in vivo antiproliferative activity in mice bearing Sarcoma 180 tumor. Among the five extracts (hexane, dichloromethane, ethyl acetate, acetone and methanol), ethyl acetate and acetone extracts displayed higher cytotoxic potential against tumor cells, with IC50 ranging from 0.8 to 4.4 microg/mL, while methanolic extract was weakly cytotoxic. Cytotoxic extracts also exhibited cell division inhibition capacity by antimitotic assay, revealing IC50 values lower than 5 microg/mL. In the in vivo antitumor assessments, ethyl acetate- and acetone-treated animals showed tumor growth inhibition ratios of 64.3 and 53.1%, respectively, with reversible toxic effects on liver and kidneys. Further studies are in progress in order to identify C. procera cytotoxic compound(s) and to understand the mechanism of action responsible for this tumor-decreasing potential.

Abstract 2704: Efficacy and candidate biomarker evaluation for the anti-MN immunoconjugate BAY 79-4620, MN-IC in MN (CAIX) positive preclinical xenograft models

Abstract BAY 79-4620 is a novel immunoconjugate consisting of a fully human monoclonal antibody directed against MN (carbonic anhydrase IX, CAIX) conjugated with the auristatin derivative MMAE currently in Phase I clinical testing. MN is overexpressed in a range of tumor types, such as gastric cancer, non-small cell lung cancer, pancreatic cancer or colorectal cancer. CAIX expression is regulated by HIF-1α and therefore associated with tumor hypoxia. Here we report on the correlation of tumor CAIX antigen expression levels, as determined by a newly developed CAIX IHC staining protocol, and the efficacy of BAY 79-4620 in six preclinical tumor models. Further, CAIX levels in xenograft tumors were compared to those in clinical samples of human tumors. Efficacy of BAY 79-4620 in tumor models increased with their CAIX expression levels. HeLa-MaTu, HT29 and PC3mm2 models characterized by the highest expression of CAIX showed 56-92 % tumor growth inhibition, when treated with 1 mg/kg BAY 79-4620. Hs746T, the tumor model with the lowest CAIX level, did not show tumor growth inhibition at 1 mg/kg MN-IC, but responded to higher doses. Analysis of CAIX expression by IHC using human tumor samples (gastric, CRC, NSCLC and breast) demonstrated that tumor cell CAIX expression varied both within and between tumor types. IHC scoring revealed that 95% of colon cancer tumors, 55% of NSCLC tumors, and 35% of breast cancer tumors assayed had ≥10% of cells scoring 2+ or 3+ by IHC. In preclinical models analysis of serum CAIX extracellular domain (ECD) by ELISA revealed an initial rise in plasma CAIX ECD as early as 2 days after 30 mg/kg BAY 79-4620 followed by a decrease to below-baseline levels. In two out of three models tested, changes or increased levels of the apoptosis marker CK18 were observed following BAY 79-4620 administration. Changes in serum CAIX ECD levels as well as CK18 will be explored as an early pharmacodynamic (PD) response markers in clinical trials for BAY 79-4620. In summary, these results demonstrate that targeted delivery of MMAE resulted in higher efficacy of BAY 79-4620 in tumor models with high CAIX expression. Responsive xenograft models were representative of clinical samples with respect to CAIX expression scored by IHC. Quantification of MN (CAIX) by IHC is a candidate stratification biomarker for the immunoconjugate BAY 79-4620 currently in Phase I testing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2704.

Abstract 5390: QBI-139, a human RNase variant in a phase I trial, works in combination

Abstract The EVade™ Ribonucleases (RNases) are a new class of anti-cancer drugs that target the RNA in cancer cells. These EVade™ RNases are variants of native mammalian RNases that have been converted to anti-cancer agents by diminishing their binding to their natural inhibitor protein. One of these EVade™ RNases, called QBI-139, has advanced to human clinical trials. QBI-139 shares 95% sequence identity with the wild type human RNase 1. QBI-139 has shown tumor growth inhibition against a variety of cancers, including: colon, non-small cell lung, ovarian, pancreatic and prostate cancers. QBI-139 is currently in a Phase I clinical trial in patients with solid tumors. A frog RNase called Ranpirnase (Alfacell) that shares only 20% sequence identity with human RNase 1 has been in clinical trials and responses have been seen in esophageal, non-small cell lung and breast cancers as well as unresectable mesothelioma. The next stage of clinical development of QBI-139 will require selection of a specific indication as well as an existing treatment regimen to be used in combination with QBI-139. The Phase I trial may provide insights about sensitive tumor types. However, mouse models of cancer will be used to select the combinations for development. QBI-139 has shown efficacy against non-small cell lung cancer (A549 cell line) in xenograft models. Cisplatin is a standard of care treatment for non-small cell lung cancer in patients. The ability of QBI-139 and cisplatin to work together to cause tumor growth inhibition was determined in a non-small cell lung cancer xenograft model (A549 cell line). Cisplatin (3 mg/kg) and QBI-139 (15 mg/kg) were used as controls. The combination of cisplatin and QBI-139 (3 and 15 mg/kg, respectively) was also tested. Cisplatin treatment resulted in tumor growth inhibition (TGI) of 60% while QBI-139 caused 76% TGI. The combination of the two drugs resulted in a TGI of 96%, strongly supporting the use of QBI-139 in combination with cisplatin for the treatment of lung cancer. Even the combination of the two drugs exhibited minimal impact on the health of the animals. EVade™ Ribonucleases are novel agents that provide a new way to target the RNA in cancer cells and are an innovative new tool for oncologists. QBI-139 has a variety of benefits, including: a novel mechanism of action with clinical support, broad in vivo anti-tumor activity alone and in combination with standard of care therapies and a strong tolerability profile. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5390.

Exploring the pharmacokinetic properties of phosphorus-containing selective HDAC 1 and 2 inhibitors (SHI-1:2)

We report the preparation and structure–activity relationships of phosphorus-containing histone deacetylase inhibitors. A strong trend between decreasing phosphorus functional group size and superior mouse pharmacokinetic properties was identified. In addition, optimized candidates showed tumor growth inhibition in xenograft studies.

In vivo targeted gene delivery by cationic nanoparticles for treatment of hepatocellular carcinoma

Transgene expression in vivo for therapeutic purposes will require methods that allow for efficient gene transfer into cells. Although current vector technologies are being improved, the development of novel vector systems with improved targeting specificity, higher transduction efficiencies and improved safety is necessary. Asialoglycoprotein receptor-targeted cationic nanoparticles for interleukin (IL)-12 encapsulation (NP1) or adsorption (NP2) have been formulated by blending poly(D,L-lactic-co-glycolic) acid (PLGA) (50 : 50) with the cationic lipid 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and the ligand asialofetuin (AF), by using a modified solvent evaporation process. We present a novel targeted lipopolymeric vector, which improves significantly the levels of luciferase gene expression in the liver upon i.v. administration. Targeted-NP2 particles showed a five- and 12-fold higher transfection activity in the liver compared to non-targeted (plain) complexes or naked pCMV DNA, respectively. On the other hand, BNL tumor-bearing animals treated with AF-NP1 containing the therapeutic gene IL-12, showed tumor growth inhibition, leading to a complete tumor regression in 75% of the treated mice, without signs of recurrence. High levels of IL-12 and interferon-gamma were detected in the sera of treated animals. Mice survival also improved considerably. Tumor treatment with AF-NP2 formulations lead only to a retardation in the tumor growth. In the present study, we have developed an efficient targeted non-viral vector for IL-12 gene transfer in hepatocellular carcinoma in vivo, by employing non-toxic cationic PLGA/DOTAP/AF nanoparticles. These results demonstrate for the first time that this cationic system could be used successfully and safely for delivery of therapeutic genes with antitumor activity into liver tumors with targeting specificity.

Synthesis and SAR of 6-chloro-4-fluoroalkylamino-2-heteroaryl-5-(substituted)phenylpyrimidines as anti-cancer agents

The synthesis and SAR of a series of 6-chloro-4-fluoroalkylamino-2-heteroaryl-5-(substituted)phenylpyrimidines as anti-cancer agents are described. This series of 2-heteroarylpyrimidines was developed by modifying a series of anti-tumor [1,2,4]triazolo[1,5- a]pyrimidines and 2-cyanoaminopyrimidines we reported earlier. For the 2-heteroaryl group, the best activity is obtained when the heteroaryl group has a nitrogen atom at the ortho-position to the pyrimidyl core. The structure–activity relationship for the rest of the molecule in this 2-heteroarylpyrimidine series mimics that of the [1,2,4]triazolo[1,5- a]pyrimidine series. Like triazolopyrimidines and 2-cyanoaminopyrimidines, the 2-heteroarylpyrimidines retain the capability to overcome multidrug resistance due to Pgp. Mechanism of action studies showed that the lead compounds behaved in the same manner as triazolopyrimidines and 2-cyanoaminopyrimidines. The lead compounds in this series are more potent than the corresponding triazolopyrimidines in vitro and in vivo. Compound 21 (PTI-868) showed tumor growth inhibition in several nude mouse xenograft models, and was selected to advance to preclinical development.

The role of p53 in the trafficking of copper-64 to tumor cell nuclei

Copper-64 (T1/2 = 12.7 h; β+: 17.8%, β-: 41%) has applications in both positron emission tomography (PET) imaging and targeted radiotherapy of cancer. Copper-64 radiopharmaceuticals have shown tumor growth inhibition with a relatively low radiation dose in animal models; however, the mechanism of cytotoxicity has not been fully elucidated. Here, we report an investigation on the potential role of the tumor suppressor protein p53 in trafficking 64Cu to tumor cell nuclei. Two EGFR expressing human colorectal cell lines (HCT 116 +/+ and HCT 116 -/-) that are positive or negative for p53 expression respectively, were used to compare internalization and nuclear localization of [64Cu]copper acetate and of 64Cu-DOTA-cetuximab, a monoclonal anti-EGFR antibody. [64Cu]copper acetate uptake into cells was similar between the two cell lines during a 24 h time course. In contrast, the uptake of [64Cu]copper acetate in the nuclei of HCT 116 +/+ cells was significantly higher than in HCT 116 -/- cells (p < 0.0001) at 24 h. There was no difference in receptor binding, receptor-mediated internalization, and efflux of 64Cu-DOTA-cetuximab between the two HCT 116 cells lines. However, nuclear localization of 64Cu-DOTA-cetuximab showed increased uptake in the nuclei of HCT 116 +/+ cells as early as 4 h. These data demonstrate that 64Cu is delivered to tumor cell nuclei in a p53 positive cell line in significantly greater amounts than in p53 negative cells by both non-specific and receptor-mediated uptake mechanisms.

In Vivo Bioluminescence Visualization of Antitumor Effects by Human MUC1 Vaccination

Recently, the use of a cancer deoxyribonucleic acid (DNA) vaccine encoding tumor-associated antigens has emerged as an immunotherapeutic strategy. In this study, we monitored tumor growth inhibition by pcDNA3-hMUC1 immunization in mice using optical imaging. To determine the anti-hMUC1-associated immune response generated by pcDNA3.1 or pcDNA3-hMUC1, we determined the concentration of interferon-gamma (IFN-gamma) protein and CD8+IFN-gamma cell numbers among lymphocytes from the draining lymph nodes of mice immunized with pcDNA3.1 or pcDNA3-hMUC1. After subcutaneously injecting CT26/hMUC1-Fluc into mice immunized with pcDNA3-hMUC1, we monitored in vivo tumor growth inhibition using an optical imaging method. The concentration of IFN-gamma protein in pcDNA3-hMUC1 was higher than that of the pcDNA3.1 group (2.7 < or = 0.08 ng/mL and 1.6 +/- 0.07 ng/mL, respectively, p < .001. The number of hMUC1-associated CD8+IFN-gamma cells in pcDNA3-hMUC1-immunized animals was 30-fold higher than in the pcDNA3.1 group. Bioluminescent images showed tumor growth inhibition in pcDNA3-hMUC1 immunized animals up to 25 days after immunization. A good correlation (r2 = .9076: pcDNA3/hMUC1 group; r2 = .7428: pcDNA3.1 group) was observed between bioluminescence signals and tumor weights in two mice in each group. We conclude that optical bioluminescent imaging offers a useful means of monitoring the antitumor effects of cancer DNA immunization in living animals.

Nuclear Uptake and Dosimetry of 64Cu-Labeled Chelator Somatostatin Conjugates in an SSTr2-Transfected Human Tumor Cell Line

64Cu radiopharmaceuticals have shown tumor growth inhibition in tumor-bearing animal models with a relatively low radiation dose that may be related to nuclear localization of the 64Cu in tumor cells. Here we address whether the nuclear localization of 64Cu from a 64Cu-labeled chelator-somatostatin conjugate is related to the dissociation of the radio-copper from its chelator. The 64Cu complex of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA) has demonstrated instability in vivo, whereas 64Cu-CB-TE2A (CB-TE2A is 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) was highly stable. Receptor binding, nuclear uptake, internalization, and efflux assays were performed to characterize the interaction with the somatostatin receptor and the intracellular fate of 64Cu-labeled chelator-peptide conjugates in A427-7 cells. From these data, the absorbed dose to cells was calculated. 64Cu-TETA-Y3-TATE (64Cu-[1]) and 64Cu-CB-TE2A-Y3-TATE (64Cu-[2]) had high affinity for somatostatin receptor subtype 2 (SSTr2) in A427-7 cells. After 3 h, 64Cu-[2] showed greater internalization (>30%) compared with 64Cu-[1] (approximately 15%). There was uptake of 64Cu-[1] in nuclei of 427-7 cells (9.4% +/- 1.7% at 24 h), whereas 64Cu-[2] showed minimal nuclear accumulation out to 24 h (1.3% +/- 0.1%). A427-7 cells were exposed to 0.40 Gy from 64Cu-[1] and exposed to 1.06 Gy from 64Cu-[2]. External beam irradiation of A427-7 cells showed <20% cell killing at 1 Gy. These results are consistent with our hypothesis that dissociation of 64Cu from TETA leads to nuclear localization. Dosimetry calculations indicated that the nuclear localization of 64Cu-[1] was not significant enough to increase the absorbed dose to the nuclei of A427-7 cells. These studies show that 64Cu localization to cell nuclei from internalizing, receptor-targeted radiopharmaceuticals is related to chelate stability.