Pancreatic Carcinoma Xenografts Research Articles

Impact of the PI3K-alpha inhibitor alpelisib on everolimus resistance and somatostatin receptor expression in an orthotopic pancreatic NEC xenograft mouse model.

The mechanistic target of rapamycin complex 1 (mTORC1) inhibitor everolimus is one of the few approved therapies for locally advanced and metastatic neuroendocrine tumours (NETs). However, after initial disease stabilisation, most patients develop resistance within 1 year. Our aim was to overcome resistance to everolimus by additional treatment with the PI3K-alpha inhibitor alpelisib in an everolimus-resistant orthotopic pancreatic neuroendocrine carcinoma xenograft mouse model. Female SCID mice underwent laparoscopic pancreatic transplantation of everolimus-sensitive (BON1KDMSO) or everolimus-resistant (BON1RR2) NET cells. Both groups were further divided into four treatment groups: placebo, everolimus, alpelisib, and everolimus + alpelisib (combination). Oral treatment was started at a tumour volume of approximately 140 mm3 and continued until 1900-2000 mm3, validated by weekly MRI. Somatostatin receptor expression and tumour viability were analysed by 68Ga-DOTATOC and 18F-FDG PET/CT. Everolimus resistance of the BON1RR2 tumours was confirmed. In the everolimus-sensitive group, everolimus alone, alpelisib alone, and combination treatment significantly prolonged survival, compared to placebo, while in the BON1RR2 group, only combination treatment significantly prolonged survival compared to placebo, but neither everolimus nor alpelisib alone. Placebo-treated everolimus-sensitive tumours grew more rapidly (median survival 45 days), compared to placebo-treated everolimus-resistant tumours (60 days). Within the everolimus-sensitive group, the combination-treated mice showed the longest median survival (52 days). Of all groups, the everolimus-resistant combination-treated group survived longest (69 days). Combination treatment with everolimus and alpelisib seems promising to overcome everolimus resistance in neuroendocrine neoplasms, and should be further examined in a clinical trial.

Nano-Targeting of Thyrointegrin αvβ3 Receptor in Solid Tumors and Impact on Radiosensitization.

Tetraiodothyroacetic acid is a ligand of thyrointegrin αvβ3, a protein that is highly expressed in various solid tumors and surrounding neovascular regions. Its nano derivative, Nano-diamino-tetrac (NDAT), has anticancer properties in preclinical models, enhances radiosensitivity, and inhibits cancer cell growth in vitro after X-ray irradiation. Using a novel experimental system developed to deliver accurate radiation dose to tumors under sterile conditions, this study establishes NDAT's radiosensitizing effect in SUIT-2 pancreatic cancer and H1299 non-small cell lung carcinoma xenografts in athymic mice for tumor-targeted radiation. In this work, low-melting-point Lipowitz alloy was used to shield normal organs and allow accurate tumor-targeted irradiation. Over a three-week period, mice with SUIT-2 xenografts received daily NDAT treatment at different doses (0, 1, 3, or 10 mg/kg body weight) and tumor-targeted irradiation (1 or 5 Gy). Validation was performed with a test dose of 30 Gy to mice bearing SUIT-2 xenografts and resulted in more than 80% reduction in tumor weight, compared to nonirradiated tumor weight. The results of this work showed that NDAT had a radiosensitizing effect in a dose-dependent manner in decreasing tumor growth and viability. An enhanced anticancer effect of NDAT (1 mg/kg body weight) was observed in mice with H1299 xenografts receiving 5 Gy tumor-targeted irradiation, indicated by decreased tumor weight and increased necrosis, compared to nonirradiated tumors. This technique demonstrated accurate tumor-targeted irradiation with new shielding methodology, and combined with thyrointegrin antagonist NDAT treatment, showed anticancer efficacy in pancreatic cancer and non-small cell lung carcinoma.

Pharmacometabolomics Identifies 3-Hydroxyadipic Acid, d-Galactose, Lysophosphatidylcholine (P-16:0), and Tetradecenoyl-l-Carnitine as Potential Predictive Indicators of Gemcitabine Efficacy in Pancreatic Cancer Patients.

Gemcitabine (GEM)-based chemotherapy is the standard regimen for the treatment of pancreatic cancer (PC). However, chemoresistance is a major challenge in PC treatment. Reliable biomarkers are urgently needed to predict the response to GEM-based therapies. GEM-sensitive (GEM-S) and GEM-resistant (GEM-R) pancreatic carcinoma xenograft models were established, and GEM monotherapy and GEM plus nanoparticle albumin-bound paclitaxel (nab-PTX) doublet therapy were administered to GEM-S/R tumor-bearing mice. Metabolomic mass spectrometry (MS) analysis of serum, liver, and tumor samples was performed using an ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometer. The results showed that both GEM monotherapy and combination therapy significantly inhibited the tumor growth in GEM-S subgroup. However, in the GEM-R subgroup, tumor growth was not significantly inhibited by GEM monotherapy, but was significantly suppressed by GEM combination therapy. Metabolic profiling analysis by hierarchical cluster analysis and partial least squares discriminant analysis showed that the differences in metabolites were most significant in serum of three types of samples in the GEM-S/R subgroups, regardless of the administration of GEM monotherapy or combination therapy. The differential metabolite analysis of serum samples revealed 38 and 26 differential metabolites between the GEM-R and GEM-S subgroups treated with GEM monotherapy or combination therapy, and four common discriminating metabolites were investigated: 3-hydroxyadipic acid, d-galactose, lysophosphatidylcholine (LysoPC) (P-16:0), and tetradecenoyl-l-carnitine. The relative amounts of the four metabolites changed significantly and consistently after GEM monotherapy or combination therapy. The levels of these four metabolites were significantly different in the GEM-S and GEM-R pancreatic carcinoma xenograft models; thus, these metabolites could be effective predictive indicators of the efficacy of chemotherapy in PC patients, regardless of the administration of GEM alone or GEM plus nab-PTX.

An albumin‑binding domain and targeting peptide‑based recombinant protein and its enediyne‑integrated analogue exhibit directional delivery and potent inhibitory activity on pancreatic cancer with K‑ras mutation.

Efficient enrichment and transmembrane transport of cytotoxic reagents are considered to be effective strategies to increase the efficiency and selectivity of antitumor drugs targeting solid tumors. In the present study, a recombinant protein ABD-LDP-Ec consisting of the albumin-binding domain (ABD), the apoprotein (LDP) of lidamycin (LDM) and an EGFR-targeting oligopeptide (Ec) was prepared by DNA recombination and bacterial fermentation, and was integrated with the enediyne chromophore (AE) of lidamycin to generate its enediyne-integrated analogue ABD-LDP-Ec-AE. ABD-LDP-Ec exhibited high binding capacity to both albumin and EGFR-positive pancreatic cancer cells, and was internalized into the cytoplasm through receptor-mediated endocytosis and albumin-driven macropinocytosis of K-ras mutant cells. In animal experiments, ABD-LDP-Ec demonstrated notable selective distribution in pancreatic carcinoma xenografts by passive targeting of albumin captured in the blood and was retained in the tumor for 48 h. ABD-LDP-Ec and ABD-LDP-Ec-AE exhibited inhibitory activity in cell proliferation and AsPC-1 ×enograft growth, and ABD-LDP-Ec-AE increased the tumor growth inhibition rate by 20% compared with natural LDM. The results indicated that the introduction of ABD-based multi-functional drug delivery may be an effective approach to improve the efficacy of antitumor drugs, especially for K-ras mutant cancers.

Photoimmunotherapy targeting biliary-pancreatic cancer with humanized anti-TROP2 antibody.

Photoimmunotherapy (PIT) is a new type of tumor‐specific treatment utilizing monoclonal antibody (mAb)‐photosensitizer conjugates and near‐infrared (NIR) light irradiation. One potential PIT target, the type I transmembrane protein TROP2, is expressed at high levels in many cancers, including pancreatic carcinoma (PC) and cholangiocarcinoma (CC), in which its expression is correlated with poor prognosis and tumor aggressiveness. In this study, we assessed the efficacy of PIT utilizing newly developed humanized anti‐TROP2 mAb conjugated to the photosensitizer IR700 (TROP2‐IR700) for PC and CC. Immunohistochemistry on PC and CC tissue microarrays confirmed that TROP2 is overexpressed in about half of PC and CC specimens. Using cultured PC and CC cells, TROP2‐IR700 localized TROP2‐specific and target‐specific cell killing was observed after NIR light irradiation. In addition, TROP2‐IR700 was localized to mouse xenograft tumors expressing TROP2 after intravenous injection. PC and CC xenograft tumor growth was significantly inhibited by TROP2‐targeted PIT relative to controls. The efficacy of TROP2‐targeted PIT in vitro and against xenografted tumors in vivo suggests promise as a therapy for human PC and CC, both of which currently have dismal prognoses and limited therapeutic options.

Intratumor Heterogeneity in Interstitial Fluid Pressure in Cervical and Pancreatic Carcinoma Xenografts

Preclinical studies have suggested that interstitial fluid pressure (IFP) is uniformly elevated in the central region of tumors, whereas clinical studies have revealed that IFP may vary among different measurement sites in the tumor center. IFP measurements are technically difficult, and it has been claimed that the intratumor heterogeneity in IFP reported for human tumors is due to technical problems. The main purpose of this study was to determine conclusively whether IFP may be heterogeneously elevated in the central tumor region, and if so, to reveal possible mechanisms and possible consequences. Tumors of two xenograft models were included in the study: HL-16 cervical carcinoma and Panc-1 pancreatic carcinoma. IFP was measured with Millar SPC 320 catheters in two positions in each tumor and related to tumor histology or the metastatic status of the host mouse. Some tumors of both models showed significant intratumor heterogeneity in IFP, and this heterogeneity was associated with a compartmentalized histological appearance (i.e., the tissue was divided into compartments separated by thick connective tissue bands) in HL-16 tumors and with a dense collagen-I-rich extracellular matrix in Panc-1 tumors, suggesting that these connective tissue structures prevented efficient interstitial convection. Furthermore, some tumors of both models developed lymph node metastases, and of the two IFP values measured in each tumor, only the higher value was significantly higher in metastatic than in non-metastatic tumors, suggesting that metastatic propensity was determined by the tumor region having the highest IFP.

Diffusion-Weighted MRI Is Insensitive to Changes in the Tumor Microenvironment Induced by Antiangiogenic Therapy

Antiangiogenic treatment (AAT) used in combination with radiation therapy or chemotherapy is a promising strategy for the treatment of several cancer diseases. The vascularity and oxygenation of tumors may be changed significantly by AAT, and consequently, a noninvasive method for monitoring AAT-induced changes in these microenvironmental parameters is needed. The purpose of this study was to evaluate the potential usefulness of diffusion-weighted magnetic resonance imaging (DW-MRI). DW-MRI was conducted with a Bruker Biospec 7.05-T scanner using four diffusion weightings and diffusion sensitization gradients in three orthogonal directions. Maps of the apparent diffusion coefficient (ADC) were calculated by using a monoexponential diffusion model. Two cervical carcinoma xenograft models (BK-12, HL-16) were treated with bevacizumab, and two pancreatic carcinoma xenograft models (BxPC-3, Panc-1) were treated with sunitinib. Pimonidazole and CD31 were used as markers of hypoxia and blood vessels, respectively, and fraction of hypoxic tissue (HFPim) and microvascular density (MVD) were quantified by analyzing immunohistochemical preparations. MVD decreased significantly after AAT in BK-12, HL-16, and BxPC-3 tumors, and this decrease was sufficiently large to cause a significant increase in HFPim in BK-12 and BxPC-3 tumors. The ADC maps of treated tumors and untreated control tumors were not significantly different in any of these three tumor models, suggesting that the AAT-induced microenvironmental changes were not detectable by DW-MRI. DW-MRI is insensitive to changes in tumor vascularity and oxygenation induced by bevacizumab or sunitinib treatment.

A Macropinocytosis-Intensifying Albumin Domain-Based scFv Antibody and Its Conjugate Directed against K-Ras Mutant Pancreatic Cancer.

Enhanced macropinocytosis has been found in K-Ras mutant pancreatic cancer cells, through which albumin can massively enter into the K-Ras-driven cancer cells, suggesting its role in serving as a macropinocytosis-intensifying drug delivery carrier. In the present study, a novel recombinant protein Fv-LDP-D3 and its reconstituted analogue Fv-LDP-D3-AE were designed and prepared. Fv is the fragment of an anti-EGFR antibody, D3 is the domain III of human serum albumin (HSA), LDP is the apoprotein of the antitumor antibiotic lidamycin (LDM), and AE is an extremely cytotoxic enediyne chromophore derived from LDM. As shown, the recombinant protein Fv-LDP-D3 presented intensive and selective binding capacity to pancreatic cancer cells and inhibited cell proliferation by blocking EGFR signaling. Moreover, Fv-LDP-D3 showed prominent tumor imaging in pancreatic carcinoma xenograft. The reconstituted, enediyne-integrated analogue Fv-LDP-D3-AE displayed highly potent cytotoxicity to pancreatic cancer cells through apoptosis induction and G2/M arrest. Fv-LDP-D3 and Fv-LDP-D3-AE markedly inhibited the tumor growth of the pancreatic carcinoma AsPC-1 xenograft. Study results indicated that the novel recombinant protein displays both EGFR-targeting and macropinocytosis-intensifying attributes, presenting a new format of scFv antibody that integrates with albumin domain III. It might be a feasible strategy to develop targeted drugs for K-Ras mutant pancreatic cancer.

Study on the therapeutic efficacy of subcutaneous pancreatic cancer xenograft tumor with ultrasound destruction of different size microbubbles

Objective To assess the therapeutic efficacy of subcutaneous transplantation pancreatic cancer in nude mice model with different size microbubbles. Methods Eighteen Balb/C nude mice with subcutaneous pancreatic carcinoma xenografts were divided into three groups: group A(6 mice) did not received microbubbles and ultrasonic irradiation; group B(6 mice) received standard microbubbles and ultrasonic cavitation treatment; group C(6 mice) received up-sized microbubbles and ultrasonic cavitation treatment. Body weight and tumor size of nude mice were measured respectively at the time points of 0, 7, 14, 21 days after three times ultrasound radiation and before ultrasound treatment. Tumor volumes were calculated.Then the mice were sacrificed finally. Results There was no significant difference in tumor volumes among three groups before treatment(P>0.05). Tumor volume continued to increase in all groups. Compared with group A, growth rate in group B and group C were lower, growth rate in group B was higher than that in group C, the difference was statistically significant(P 0.05). RBV and RBF were decreased significantly after 3 days treatment in group B and group C(P 0.05). Conclusions The cavitation effect of up-sized microbubbles is more efficient for mice subcutaneous pancreatic cancer xenograft tumor inhibition compared with standard microbubbles. Key words: Sonication; Pancreatic neoplasms; Microbubbles; Neoplasms, vascular tissue

Mithramycin-loaded mPEG-PLGA nanoparticles exert potent antitumor efficacy against pancreatic carcinoma.

Previous studies have shown that mithramycin A (MIT) is a promising candidate for the treatment of pancreatic carcinoma through inhibiting transcription factor Sp1. However, systemic toxicities may limit its clinical application. Here, we report a rationally designed formulation of MIT-loaded nanoparticles (MIT-NPs) with a small size and sustained release for improved passive targeting and enhanced therapeutic efficacy. Nearly spherical MIT-NPs with a mean particle size of 25.0±4.6 nm were prepared by encapsulating MIT into methoxy poly(ethylene glycol)-block-poly(d,l-lactic-co-glycolic acid) (mPEG-PLGA) nanoparticles (NPs) with drug loading of 2.11%±0.51%. The in vitro release of the MIT-NPs lasted for >48 h with a sustained-release pattern. The cytotoxicity of MIT-NPs to human pancreatic cancer BxPC-3 and MIA Paca-2 cells was comparable to that of free MIT. Determined by flow cytometry and confocal microscopy, the NPs internalized into the cells quickly and efficiently, reaching the peak level at 1–2 h. In vivo fluorescence imaging showed that the prepared NPs were gradually accumulated in BxPC-3 and MIA Paca-2 xenografts and retained for 168 h. The fluorescence intensity in both BxPC-3 and MIA Paca-2 tumors was much stronger than that of various tested organs. Therapeutic efficacy was evaluated with the poorly permeable BxPC-3 pancreatic carcinoma xenograft model. At a well-tolerated dose of 2 mg/kg, MIT-NPs suppressed BxPC-3 tumor growth by 96%. Compared at an equivalent dose, MIT-NPs exerted significantly higher therapeutic effect than free MIT (86% versus 51%, P<0.01). Moreover, the treatment of MIT and MIT-NPs reduced the expression level of oncogene c-Myc regulated by Sp1, and notably, both of them decreased the protein level of CD47. In summary, the novel formulation of MIT-NPs shows highly therapeutic efficacy against pancreatic carcinoma xenograft. In addition, MIT-NPs can downregulate CD47 expression, implying that it might play a positive role in cancer immunotherapy.

Magnetic resonance imaging of RRx-001 pharmacodynamics in preclinical tumors.

RRx-001 is an anticancer agent that subjects cancer cells to reactive oxygen/nitrogen species (ROS/RNS) and acts as an epigenetic modifier. We have used a thiol-bearing MRI contrast agent, Gd-LC7-SH, to investigate the pharmacodynamics of RRx-001 in CHP-100 Ewing's Sarcoma, HT-29 colorectal carcinoma, and PANC-1 pancreatic carcinoma xenografts in SCID mice. Binding of Gd-LC7-SH to the Cys34 residue on plasma albumin prolongs retention in the tumor microenvironment and increases tumor enhancement on MRI. Mice were imaged by MRI and in vivo T1 maps acquired 50 min (T150 min) after injection of 0.05 mmol/kg Gd-LC7-SH (i.v.) at baseline and 1, 24, and 72 h post-treatment with 10 mg/kg RRx-001 (i.v.). Consistent with an indirect thiol-modifying activity of RRx-001, tumor T150 min at 1 h post-drug was significantly longer than pre-drug tumor T150 min in all three tumor models, with the T150 min remaining significantly longer than baseline through 72 h post-drug in the HT-29 and PANC-1 tumors. The T150 min of CHP-100 tumors recovered to baseline by 24 h post-drug, suggesting a robust anti-oxidant response to the RRx-001 challenge that was presaged by a marked increase in perfusion at 1 h post-drug measured by DCE-MRI. MRI enhanced with Gd-LC7-SH provides a mechanistically rational biomarker of RRx-001 pharmacodynamics.

A recombinantly tailored β-defensin that displays intensive macropinocytosis-mediated uptake exerting potent efficacy against K-Ras mutant pancreatic cancer.

K-Ras mutant pancreatic cancer cells display intensive macropinocytosis, indicating that this process may be exploited in the design of anticancer targeted therapies. In this study, we constructed a macropinocytosis-oriented recombinantly tailored defensin (DF-HSA) which consists of human β-defensin-2 (DF) and human serum albumin (HSA). The macropinocytosis intensity and cytotoxicity of DF-HSA were investigated in K-Ras mutant MIA PaCa-2 cells and wild-type BxPC-3 cells. As found, the DF-HSA uptake in MIA PaCa-2 cells was much higher than that in wild-type BxPC-3 cells. Correspondingly, the cytotoxicity of DF-HSA to MIA PaCa-2 cells was more potent than that to BxPC-3 cells. In addition, the cytotoxicity of DF-HSA was much stronger than that of β-defensin HBD2. DF-HSA suppressed cancer cell proliferation and induced mitochondrial pathway apoptosis. Notably, DF-HSA significantly inhibited the growth of human pancreatic carcinoma MIA PaCa-2 xenograft in athymic mice at well tolerated dose. By in vivo imaging, DF-HSA displayed a prominent accumulation in the tumor. The study indicates that the recombinantly tailored β-defensin can intensively enter into the K-Ras mutant pancreatic cancer cells through macropinocytosis-mediated process and exert potent therapeutic efficacy against the pancreatic carcinoma xenograft. The novel format of β-defensin may play an active role in macropinocytosis-mediated targeting therapy.

Sonoporation enhances liposome accumulation and penetration in tumors with low EPR

The Enhanced Permeability and Retention (EPR) effect is a highly variable phenomenon. To enhance EPR-mediated passive drug targeting to tumors, several different pharmacological and physical strategies have been evaluated over the years, including e.g. TNFα-treatment, vascular normalization, hyperthermia and radiotherapy. Here, we systematically investigated the impact of sonoporation, i.e. the combination of ultrasound (US) and microbubbles (MB), on the tumor accumulation and penetration of liposomes. Two different MB formulations were employed, and their ability to enhance liposome accumulation and penetration was evaluated in two different tumor models, which are both characterized by relatively low levels of EPR (i.e. highly cellular A431 epidermoid xenografts and highly stromal BxPC-3 pancreatic carcinoma xenografts). The liposomes were labeled with two different fluorophores, enabling in vivo computed tomography/fluorescence molecular tomography (CT-FMT) and ex vivo two-photon laser scanning microscopy (TPLSM). In both models, in spite of relatively high inter- and intra-individual variability, a trend towards improved liposome accumulation and penetration was observed. In treated tumors, liposome concentrations were up to twice as high as in untreated tumors, and sonoporation enhanced the ability of liposomes to extravasate out of the blood vessels into the tumor interstitium. These findings indicate that sonoporation may be a useful strategy for improving drug targeting to tumors with low EPR.

The anticancer effects of supinoxin (RX-5902) in pancreatic carcinoma.

238 Background: DEAD box RNA helicase DDX5/p68, and its phosphorylated form in particular, may play several important roles in cancer by means of cell transformation, epithelial mesenchymal transition (EMT), and cell migration, deeming it a promising target for novel anti-cancer therapeutics. We have previously shown that Supinoxin (RX-5902) interacts with phosphorylated p68 on Tyr593, interfering with the phosphorylated p68-β-catenin signaling pathway. Supinoxin also inhibits motility of MDA-MB231 breast cancer cell lines and could potentially prevent metastasis in cancer. Methods: In this study, we first demonstrated anti-proliferative effects in several cell lines originated from pancreas (5 cell lines) with a high level of sensitivity to Supinoxin (IC50 of 18 nM). We also sought to examine the tumor growth inhibition (TGI) and/or tumor growth delay (TGD), and survival benefits of Supinoxin in the human pancreatic carcinoma (MiaPaCa-2) xenograft mouse model. Results: In the MiaPaCa-2 model, at 50 and 70 mg/kg daily (oral, 5 days on/2 days off) for 3 weeks, both doses delayed tumor growth significantly (83% and 339%; P &lt; 0.001). All animals in the high dose showed complete regression (CR) and completing the study as tumor free survival (TFS; Day 65); one animal showed CR and TFS in the lower dose. Gemcitabine (120 mg/kg ip; Q3D for 4 weeks) resulted in TGD of 71% (P &lt; 0.001), with no CRs. Supinoxin did not result in a reduction in body weight gain, treatment related deaths, or clinical observations in this tumor model. Conclusions: These data support the potential therapeutic activity of Supinoxin in pancreatic cancer. A Phase 1 study of Supinoxin on relapse/refractory solid tumors is ongoing (NCT02003092).

Functional imaging of interstitial brachytherapy in pancreatic carcinoma xenografts using spectral CT: how does iodine concentration correlate with standardized uptake value of18FDG-PET-CT?

This study aimed to investigate the correlation between iodine concentration (IC) for the quantitative analysis of spectral CT and maximum standardized uptake value (SUVmax) of 18 fludeoxyglucose positron emission tomography-CT ((18)FDG PET-CT) as an indicator of therapeutic response to interstitial brachytherapy in transplanted human pancreatic carcinomas in BALB/c-nu mice. Xenograft models were created by subcutaneous injection of SW1990 human pancreatic cancer cell suspensions into immunodeficient BALB/c-nu mice. 30 mice bearing SW1990 human pancreatic cancer cell xenografts were randomly separated into two groups: experimental (n = 15; 1.0 mCi) and control (n = 15, 0 mCi). After 2 weeks of treatment, spectral CT and (18)FDG micro-PET-CT scan were performed. IC values and SUVmax in the lesions were measured. IC normalized to the muscle tissue is indicated as nIC. The relationships between the nIC and SUVmax of the transplantation tumours were analysed. 2 weeks after treatment, the nIC in three-phase scans and SUVmax of the experimental group were significantly lower than those of the control group. The nIC values of the three-phase scans have certain positive correlation with the SUVmax values (r = 0.69, p < 0.05; r = 0.73 and p < 0.05; r = 0.80, p < 0.05 in the 10-, 25- and 60-s phase, respectively). Spectral CT could serve as a valuable imaging modality, as our results suggest that nIC correlates with SUVmax of (18)FDG PET-CT for evaluating the therapeutic effect of (125)I interstitial brachytherapy in a pancreatic carcinoma xenograft. Spectral CT offers opportunities to assess the therapeutic response of pancreatic cancer. This study supports the conclusion that nIC values in spectral CT could also serve as a valuable functional imaging parameter for early monitoring and evaluation of the therapeutic response of (125)I interstitial brachytherapy mouse models because the nIC correlates with the SUVmax of (18)FDG PET-CT.

Abstract 2576: Enhanced antitumor efficacy by sequential application of Wnt pathway antagonists in combination with taxanes

Abstract The Wnt/beta-catenin pathway, which signals through the Frizzled (FZD) receptor family and several co-receptors, has long been implicated in cancer. We have previously demonstrated that inhibition of Wnt/beta-catenin signaling by vantictumab (anti-Fzd7, OMP-18R5) or ipafricept (FZD8-Fc, OMP-54F28) inhibits tumor growth, decreases tumorigenicity and induces differentiation in solid tumors. The anti-tumor effect of our Wnt antagonists is most evident in combination with chemotherapeutic agents. We sought to determine if the anti-tumor effect of Wnt pathway inhibitors varied with different chemotherapeutic agents. We compared the growth inhibitory effect of vantictumab and ipafricept with either taxanes (paclitaxel and nab-paclitaxel) or with DNA synthesis inhibitors (gemcitabine and carboplatin) in patient-derived tumor xenografts. We observed enhanced anti-tumor activity when combining vantictumab or ipafricept with nab-paclitaxel or paclitaxel compared to the combination with gemcitabine or carboplatin in pancreatic ductal carcinoma and serous ovarian cancer xenograft models. Histologic analysis in a pancreatic ductal carcinoma indicated that nab-paclitaxel increased mitotic cells and beta-catenin levels. Importantly, the addition of vantictumab to nab-paclitaxel reversed the nab-paclitaxel-induced increase in mitotic cells and beta-catenin expression. A potential mechanism to account for these results involves the observation that Wnt/beta-catenin signaling is under cell cycle control and peaks at the G2/M phase. Taxanes inhibit microtubule function and block the cell cycle at G2/M. In contrast, other chemotherapeutic agents, such as platinum compounds and nucleoside analogs, inhibit DNA synthesis and block cell proliferation at S phase. Our findings suggest that combination of Wnt blockade with chemotherapeutic agents, such as taxanes, that induce G2/M arrest may resulted in enhanced anti-tumor activity. The optimal synergy of anti-Wnt plus taxane combination occurs when the antibody was applied prior to taxane. Further analyses in serous ovarian tumors reveal that pre-treatment with ipafricept resulted in dysregulated beta-cetenin localization within giant multi-nucleated cells and up-regulation of genes associated with negative regulators of G1 progression. Our work provides evidence for the enhanced anti-tumor effect of Wnt pathway inhibitors in combination with taxanes and highlights the importance of preclinical examination to identify the most efficacious combination therapy regimens and the timing of antibody action for Wnt antagonists in combination with taxanes for optimal treatment efficacy. Citation Format: Wan-Ching Yen, Marcus Fischer, Belinda Cancilla, Fiore Cattaruzza, Tracy Tang, Pete Yeung, John Lewicki, Austin Gurney, Timothy Hoey. Enhanced antitumor efficacy by sequential application of Wnt pathway antagonists in combination with taxanes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2576. doi:10.1158/1538-7445.AM2015-2576

Identification of TAX2 peptide as a new unpredicted anti-cancer agent.

The multi-modular glycoprotein thrombospondin-1 (TSP-1) is considered as a key actor within the tumor microenvironment. Besides, TSP-1 binding to CD47 is widely reported to regulate cardiovascular function as it promotes vasoconstriction and angiogenesis limitation. Therefore, many studies focused on targeting TSP-1:CD47 interaction, aiming for up-regulation of physiological angiogenesis to enhance post-ischemia recovery or to facilitate engraftment. Thus, we sought to identify an innovative selective antagonist for TSP-1:CD47 interaction. Protein-protein docking and molecular dynamics simulations were conducted to design a novel CD47-derived peptide, called TAX2. TAX2 binds TSP-1 to prevent TSP-1:CD47 interaction, as revealed by ELISA and co-immunoprecipitation experiments. Unexpectedly, TAX2 inhibits in vitro and ex vivo angiogenesis features in a TSP-1-dependent manner. Consistently, our data highlighted that TAX2 promotes TSP-1 binding to CD36-containing complexes, leading to disruption of VEGFR2 activation and downstream NO signaling. Such unpredicted results prompted us to investigate TAX2 potential in tumor pathology. A multimodal imaging approach was conducted combining histopathological staining, MVD, MRI analysis and μCT monitoring for tumor angiography longitudinal follow-up and 3D quantification. TAX2 in vivo administrations highly disturb syngeneic melanoma tumor vascularization inducing extensive tumor necrosis and strongly inhibit growth rate and vascularization of human pancreatic carcinoma xenografts in nude mice.

Preliminary evaluation of 1′-[18F]fluoroethyl-β-D-lactose ([18F]FEL) for detection of pancreatic cancer in nude mouse orthotopic xenografts

IntroductionEarly detection of pancreatic cancer could save many thousands of lives. Non-invasive diagnostic imaging, including PET with [18F]FDG, has inadequate resolution for detection of small (2–3mm) pancreatic tumours. We demonstrated the efficacy of PET imaging with an 18F-labelled lactose derivative, [18F]FEDL, that targets HIP/PAP, a biomarker that is overexpressed in the peritumoural pancreas. We developed another analogue, 1-[18F]fluoroethyl lactose ([18F]FEL), which is simpler to synthesise, for the same application. We conducted a preliminary evaluation of the new probe and its efficacy in detecting orthotopic pancreatic carcinoma xenografts in mice. MethodsXenografts were developed in nude mice by injecting L3.6pl/GL+ pancreatic carcinoma cells into the pancreas of each mouse. Tumour growth was monitored by bioluminescence imaging (BLI); accuracy of BLI tumour size estimates was verified by MRI in two representative mice. When the tumour size reached approximately 2–3mm, the animals were injected with [18F]FEL (3.7MBq) and underwent static PET/CT scans. Blood samples were collected at 2, 5, 10, 20 and 60min after [18F]FEL injection to track blood clearance. Following imaging, animals were sacrificed and their organs and tumours/pancreatic tissue were collected and counted on a gamma counter. Pancreas, including tumour, was frozen, sliced and used for autoradiography and immunohistochemical analysis of HIP/PAP expression. ResultsTumour growth was rapid, as observed by BLI and MRI. Blood clearance of [18F]FEL was bi-exponential, with half-lives of approximately 3.5min and 40min. Mean accumulation of [18F]FEL in the peritumoural pancreatic tissue was 1.29±0.295 %ID/g, and that in the normal pancreas of control animals was 0.090±0.101 %ID/g. [18F]FEL was cleared predominantly by the kidneys. Comparative analysis of autoradiographic images and immunostaining results demonstrated a correlation between [18F]FEL binding and HIP/PAP expression. Conclusion[18F]FEL may be useful for non-invasive imaging of early-stage pancreatic tumours by PET. The results warrant further studies.

Translational assessment of mitochondrial dysfunction of pancreatic cancer from in vitro gene microarray and animal efficacy studies, to early clinical studies, via the novel tumor-specific anti-mitochondrial agent, CPI-613.

Via genetic alterations, malignant transformation and proliferation are associated with extensive alterations of mitochondrial energy metabolism of tumor cells. Thus, inhibition of the altered form of mitochondrial energy metabolism of tumor cells may be an effective therapy for cancers. This study performed translational assessment of mitochondrial dysfunction of pancreatic cancer from in vitro gene microarray and animal efficacy studies, to early clinical studies, via the novel tumor-specific anti-mitochondrial agent, CPI-613. The gene profiles of BxPC-3 human pancreatic tumor cells and non-transformed NIH-3T3 mouse fibroblast cells (negative control), after CPI-613 or sham treatment, were assessed and compared using microarray technique. The anti-cancer efficacies of CPI-613 and Gemcitabine were assessed and compared in mice with xenograft from inoculation of BxPC-3 human pancreatic tumor cells, based on the degree of tumor growth inhibition and prolongation of survival when compared to vehicle treatment. The anti-cancer activities, according to overall survival (OS), of CPI-613 alone and in combination with Gemcitabine were assessed in patients with Stage IV pancreatic cancer. Microarray studies indicated that CPI-613 down-regulated the expression of Cyclin D3, E1, E2, F, A2, B1 and CDK2 genes of BxPC-3 pancreatic cancer cells but not non-transformed NIH-3T3 mouse fibroblast cells (negative control). In mice with pancreatic carcinoma xenografts, four weekly intraperitoneal injections of either CPI-613 (25 mg/kg/administration) or Gemcitabine (50 mg/kg/administration) inhibited tumor growth and prolonged survival when compared to vehicle treatment. The degree of tumor growth inhibition was ~2×, and prolongation of survival was ~4×, greater with CPI-613 treatment than with Gemcitabine treatment. In patients with Stage IV advanced pancreatic cancer, CPI-613 at 420-1,300 mg/m(2), given twice weekly for three weeks followed by a week of rest (i.e., 3-week-on-1-week-off) as monotherapy, provided median OS of 15 months in three patients. CPI-613 at 150-320 mg/m(2) given twice weekly on the 3-week-on-1-week-off dosing schedule, coinciding with Gemcitabine (1,000 mg/m(2)) given once weekly on the 3-week-on-1-week-off dosing schedule, provided median OS of 17.8 months in four patients. These median OS values from CPI-613 monotherapy and CPI-613 + Gemcitabine treatment tend to be longer than those in patients treated with Abraxane + Gemcitabine combination or FOLFININOX (median OS ~12 months). The dysfunctional mitochondria of pancreatic cancer cells was translationable from in vitro gene alteration and animal tumor model studies to patients with advanced Stage IV pancreatic cancer, as reflected by the anti-cancer activities of the tumor-specific anti-mitochondrial agent, CPI-613, in these studies.

Spectral CT evaluation of interstitial brachytherapy in pancreatic carcinoma xenografts: preliminary animal experience.

We sought to evaluate the capability of spectral CT to detect the therapeutic response to (125)I interstitial brachytherapy in a pancreatic carcinoma xenograft nude mouse model. Twenty mice bearing SWl990 human pancreatic cancer cell xenografts were randomly separated into two groups: experimental (n = 10; 1.0 mCi) and control (n = 10; 0 mCi). After a two-week treatment, spectral CT was performed. Contrast-to-noise ratio (CNR) and iodine concentration (IC) in the lesions were measured and normalized to the muscle tissue, and nIC CD31 immunohistochemistry was used to measure microvessel density (MVD). The relationships between the nIC and MVD of the tumours were analysed. The nIC of the experimental group was significantly lower than that of the control group during the multiphase examination. A significant difference in the MVD was observed between the two groups (P <0.001). The nIC values of the three-phase scans have a certain positive correlation with MVD (r = 0.57, p < 0.0001; r = 0.48, p = 0.002; r = 0.63, p = 0.0017 in the 10, 25, and 60 s phase, respectively). Spectral CT can be a useful non-invasive imaging modality in evaluating the therapeutic effect of (125)I interstitial brachytherapy to a pancreatic carcinoma. Spectral CT offers opportunities to assess therapeutic response in pancreatic cancer cases. Spectral CT findings correlated with vascular changes associated with (125)I seed implantation. Spectral CT with monochromatic imaging removed most (125)I seed artefacts.