Antitumor activity of AZD0754, a dnTGFβRII-armored, STEAP2-targeted CAR-T cell therapy, in prostate cancer

Prostate cancer is generally considered an immunologically "cold" tumor type that is insensitive to immunotherapy. Targeting surface antigens on tumors through cellular therapy can induce a potent antitumor immune response to "heat up" the tumor microenvironment. However, many antigens expressed on prostate tumor cells are also found on normal tissues, potentially causing on-target, off-tumor toxicities and a suboptimal therapeutic index. Our studies revealed that six-transmembrane epithelial antigen of prostate-2 (STEAP2) was a prevalent prostate cancer antigen that displayed high, homogeneous cell surface expression across all stages of disease with limited distal normal tissue expression, making it ideal for therapeutic targeting. A multifaceted lead generation approach enabled development of an armored STEAP2 chimeric antigen receptor T cell (CAR-T) therapeutic candidate, AZD0754. This CAR-T product was armored with a dominant-negative TGF-β type II receptor, bolstering its activity in the TGF-β-rich immunosuppressive environment of prostate cancer. AZD0754 demonstrated potent and specific cytotoxicity against antigen-expressing cells in vitro despite TGF-β-rich conditions. Further, AZD0754 enforced robust, dose-dependent in vivo efficacy in STEAP2-expressing cancer cell line-derived and patient-derived xenograft mouse models, and exhibited encouraging preclinical safety. Together, these data underscore the therapeutic tractability of STEAP2 in prostate cancer as well as build confidence in the specificity, potency, and tolerability of this potentially first-in-class CAR-T therapy.

Exploring the expression of Adenosine Pathway-Related Markers CD73 and CD39 in Colorectal and Pancreatic Carcinomas Characterized by Multiplex Immunofluorescence: A Pilot Study

INTRODUCTION

Generating high levels of immunosuppressive adenosine in the tumor microenvironment contributes to cancer immune evasion. CD39 and CD73 hydrolyze adenosine triphosphate into adenosine; thus, efforts have been made to target this pathway for cancer immunotherapy. Our objective was optimizing a multiplex immunofluorescence (mIF) panel to explore the role of CD39 and CD73 within the tumor microenvironment.

MATERIALS AND METHODS

In three-time points, a small cohort (n=8 ) of colorectal and pancreatic adenocarcinomas were automated staining using an mIF panel against CK, CD3, CD8, CD20, CD39, CD73 and CD68 to compare them with individual markers immunohistochemistry (IHC) for internal panel validation. Densities of immune cells and distances from different tumor-associated immune cells to tumor cells were exploratory assessment and compared with clinicopathologic variables and outcomes.

RESULTS

Comparing the three-time points and individual IHC staining results, we demonstrated high reproducibility of the mIF panel. CD39 and CD73 expression was low in malignant cells; the exploratory analysis showed higher densities of CD39 expression by various cells, predominantly stromal cells, followed by T cells, macrophages, and B cells. No expression of CD73 by B cells or macrophages was detected. Distance analysis revealed proximity of cytotoxic T cells, macrophages, and T cells expressing CD39 to malignant cells, suggesting a close regulatory signal driven by this adenosine marker.

CONCLUSIONS

We optimized an mIF panel for detection of markers in the adenosine pathway, an emerging clinically relevant pathway. The densities and spatial distribution demonstrated that this pathway may modulate aspects of the tumor immune microenvironment.

Mass spectrometry quantifies target engagement for a KRASG12C inhibitor in FFPE tumor tissue

BACKGROUND

Quantification of drug-target binding is critical for confirming that drugs reach their intended protein targets, understanding the mechanism of action, and interpreting dose-response relationships. For covalent inhibitors, target engagement can be inferred by free target levels before and after treatment. Targeted mass spectrometry assays offer precise protein quantification in complex biological samples and have been routinely applied in pre-clinical studies to quantify target engagement in frozen tumor tissues for oncology drug development. However, frozen tissues are often not available from clinical trials so it is critical that assays are applicable to formalin-fixed, paraffin-embedded (FFPE) tissues in order to extend mass spectrometry-based target engagement studies into clinical settings.

METHODS

Wild-type RAS and RASG12C was quantified in FFPE tissues by a highly optimized targeted mass spectrometry assay that couples high-field asymmetric waveform ion mobility spectrometry (FAIMS) and parallel reaction monitoring (PRM) with internal standards. In a subset of samples, technical reproducibility was evaluated by analyzing consecutive tissue sections from the same tumor block and biological variation was accessed among adjacent tumor regions in the same tissue section.

RESULTS

Wild-type RAS protein was measured in 32 clinical non-small cell lung cancer tumors (622-2525 amol/µg) as measured by FAIMS-PRM mass spectrometry. Tumors with a known KRASG12C mutation (n = 17) expressed a wide range of RASG12C mutant protein (127-2012 amol/µg). The variation in wild-type RAS and RASG12C measurements ranged 0-18% CV across consecutive tissue sections and 5-20% CV among adjacent tissue regions. Quantitative target engagement was then demonstrated in FFPE tissues from 2 xenograft models (MIA PaCa-2 and NCI-H2122) treated with a RASG12C inhibitor (AZD4625).

CONCLUSIONS

This work illustrates the potential to expand mass spectrometry-based proteomics in preclinical and clinical oncology drug development through analysis of FFPE tumor biopsies.

Harvest of Confusion: Immigration Reform and California Agriculture

Agriculture was a major stumbling block to immigration reform, largely because Congress was unwilling to assign explicit priorities to the competing goals of protecting American workers and admitting supplemental immigrant farmworkers. This article describes the Special Agricultural Worker or SAW legalization program that generated 700,000 applications in California and the hypothetical calculations required to determine whether Replenishment Agricultural Workers or RAWs will be admitted to the United States to do farmwork. The paper concludes that immigration reform did not resolve the century-old debate over agriculture's “need” for alien workers; instead, SAWs and RAWs have contributed to the harvest of confusion on farm labor.

Agricultural Development and Emigration: Rhetoric and Reality

The untested premise of trade liberalizing U.S. development programs such as the Caribbean Basin Initiative is that commodity trade can substitute for international labor migration. Analysis of U.S. tomato producing regions in Sinaloa, Mexico and Florida suggests that the effect of trade liberalization of international labor migration is uncertain.

The Uncertain Connection: Free Trade and Rural Mexican Migration to the United States

Will a North American Free Trade Agreement (NAFTA) decrease Mexican migration to the United States, as the U.S. and Mexican governments assert, or increase migration beyond the movement that would otherwise occur, as NAFTA critics allege? This article argues that it is easy to overestimate the additional emigration from rural Mexico owing to NAFTA-related economic restructuring in Mexico. The available evidence suggests four major reasons why Mexican emigration may not increase massively, despite extensive restructuring and displacement from traditional agriculture. First, many rural dwellers in Mexico already have diversified their sources of income, making them less dependent on income earned from producing agricultural commodities like corn that will be most affected by NAFTA. Second, a free trade zone might induce more U.S. agricultural producers to expand in Mexico during the 1990s, creating additional jobs there instead of in the United States. Third, the links between internal migration in Mexico and emigration from Mexico are not as direct as is often assumed; even if economic restructuring increases internal population movements in Mexico, this may not translate into a great deal of international emigration. Finally, European experience teaches that free trade and economic integration can be phased-in in a manner which does not produce significant emigration, even under a freedom of movement regime. NAFTA-related economic displacement in Mexico may yield an initial wave of migration to test the U.S. labor market, but this migration should soon diminish if the jobs that these migrants seek shift to Mexico.

Development, Employment, and Migration

The concept of Asian Pacific panethnicity is examined in the light of the growing numbers and diversity of the population in the 1990s. The term ‘Asian American’ originated in the civil rights period of the 1960s to help unify Asian groups in the common struggle against negative stereotypes and discrimination. Revised immigration laws, new immigrant groups and continued hostility have brought new challenges, and it is argued that Asian Pacific Americans as a group can provide important leadership for the U.S.'s transformation to a more truly multicultural society.

Identification of Different Classes of Luminal Progenitor Cells within Prostate Tumors

Primary prostate cancer almost always has a luminal phenotype. However, little is known about the stem/progenitor properties of transformed cells within tumors. Using the aggressive Pten/Tp53-null mouse model of prostate cancer, we show that two classes of luminal progenitors exist within a tumor. Not only did tumors contain previously described multipotent progenitors, but also a major population of committed luminal progenitors. Luminal cells, sorted directly from tumors or grown as organoids, initiated tumors of adenocarcinoma or multilineage histological phenotypes, which is consistent with luminal and multipotent differentiation potentials, respectively. Moreover, using organoids we show that the ability of luminal-committed progenitors to self-renew is a tumor-specific property, absent in benign luminal cells. Finally, a significant fraction of luminal progenitors survived in vivo castration. In all, these data reveal two luminal tumor populations with different stem/progenitor cell capacities, providing insight into prostate cancer cells that initiate tumors and can influence treatment response.

A preclinical orthotopic model for glioblastoma recapitulates key features of human tumors and demonstrates sensitivity to a combination of MEK and PI3K pathway inhibitors

Current therapies for glioblastoma multiforme (GBM), the highest grade malignant brain tumor, are mostly ineffective, and better preclinical model systems are needed to increase the successful translation of drug discovery efforts into the clinic. Previous work describes a genetically engineered mouse (GEM) model that contains perturbations in the most frequently dysregulated networks in GBM (driven by RB, KRAS and/or PI3K signaling and PTEN) that induce development of Grade IV astrocytoma with properties of the human disease. Here, we developed and characterized an orthotopic mouse model derived from the GEM that retains the features of the GEM model in an immunocompetent background; however, this model is also tractable and efficient for preclinical evaluation of candidate therapeutic regimens. Orthotopic brain tumors are highly proliferative, invasive and vascular, and express histology markers characteristic of human GBM. Primary tumor cells were examined for sensitivity to chemotherapeutics and targeted drugs. PI3K and MAPK pathway inhibitors, when used as single agents, inhibited cell proliferation but did not result in significant apoptosis. However, in combination, these inhibitors resulted in a substantial increase in cell death. Moreover, these findings translated into the in vivo orthotopic model: PI3K or MAPK inhibitor treatment regimens resulted in incomplete pathway suppression and feedback loops, whereas dual treatment delayed tumor growth through increased apoptosis and decreased tumor cell proliferation. Analysis of downstream pathway components revealed a cooperative effect on target downregulation. These concordant results, together with the morphologic similarities to the human GBM disease characteristics of the model, validate it as a new platform for the evaluation of GBM treatment.

Pathway-specific engineered mouse allograft models functionally recapitulate human serous epithelial ovarian cancer

The high mortality rate from ovarian cancers can be attributed to late-stage diagnosis and lack of effective treatment. Despite enormous effort to develop better targeted therapies, platinum-based chemotherapy still remains the standard of care for ovarian cancer patients, and resistance occurs at a high rate. One of the rate limiting factors for translation of new drug discoveries into clinical treatments has been the lack of suitable preclinical cancer models with high predictive value. We previously generated genetically engineered mouse (GEM) models based on perturbation of Tp53 and Rb with or without Brca1 or Brca2 that develop serous epithelial ovarian cancer (SEOC) closely resembling the human disease on histologic and molecular levels. Here, we describe an adaptation of these GEM models to orthotopic allografts that uniformly develop tumors with short latency and are ideally suited for routine preclinical studies. Ovarian tumors deficient in Brca1 respond to treatment with cisplatin and olaparib, a PARP inhibitor, whereas Brca1-wild type tumors are non-responsive to treatment, recapitulating the relative sensitivities observed in patients. These mouse models provide the opportunity for evaluation of effective therapeutics, including prediction of differential responses in Brca1-wild type and Brca1–deficient tumors and development of relevant biomarkers.

Carcinoma initiation via RB tumor suppressor inactivation: a versatile approach to epithelial subtype-dependent cancer initiation in diverse tissues

Carcinomas arise in a complex microenvironment consisting of multiple distinct epithelial lineages surrounded by a variety of stromal cell types. Understanding cancer etiologies requires evaluating the relationship among cell types during disease initiation and through progression. Genetically engineered mouse (GEM) models facilitate the prospective examination of early oncogenic events, which is not possible in humans. Since most solid tumors harbor aberrations in the RB network, we developed an inducible GEM approach for the establishment and assessment of carcinoma initiation in a diverse range of epithelial tissues and subtypes upon inactivation of RB-mediated tumor suppression (RB-TS). The system allows independent assessment of epithelial subtypes that express either cytokeratins (K) 18 or 19. By Cre-dependent expression of a protein that dominantly inactivates RB and functionally redundant proteins p107 and p130, neoplasia could be initiated in either K18 or K19 expressing cells of numerous tissues. By design, because only a single pathway aberration was engineered, carcinomas developed stochastically only after long latency. Hence, this system, which allows for directed cell type-specific carcinoma initiation, facilitates further definition of events that can progress neoplasms to aggressive cancers via engineered, carcinogen-induced and/or spontaneous evolution.

Abstract C11: Combined inhibition of MEK and PI3 kinase signaling results in improved survival in a preclinical orthotopic model for human glioblastoma multiforme

Glioblastoma multiforme (GBM; astrocytoma grade IV) is the most frequent and aggressive brain tumor for which no effective therapy is currently available. It has been shown that PI3K, RTK/RAS, and Rb signaling are commonly altered in human GBM. We utilized a genetically engineered mouse (GEM) model for GBM, designated “TRP,” that expresses GFAP-T121 (T; for Rb suppression), the KrasG12D mutation (R), and is heterozygous for a PTEN null allele (P), to develop an orthotopic mouse model for the preclinical evaluation of potential therapeutics for GBM treatment. Although the de novo TRP brain tumor GEM model recapitulates features of human GBM including tissue invasion, pseudopalisading necrosis, and dense vascularization, the latency to tumorigenesis (4-6 months) makes its use as a preclinical model for drug screening challenging. Therefore we isolated primary GBM cells from TRP GEMs and injected cells intracranially (IC) into syngeneic mouse brains. Recipient mice developed grade IV astrocytomas and recapitulated TRP GEM tumor histopathology. The orthotopic tumors presented linear foci of necrosis with peudopalisading by neoplastic cells that are hallmarks of human GBM, and were highly proliferative, invasive, and vascular. In addition, immunohistochemistry analysis of TRP orthotopic tumors identified markers characteristic of human GBM, and tumor progression was readily examined by serial MRI. We used primary tumor cells derived from the TRP model in cell proliferation assays and found that PI3K and MAPK pathway inhibitors used as single agents inhibited cell growth alone, but did not result in significant apoptosis. However, when cells were treated with a combination of agents such as BKM120 (a pan-PI3K inhibitor currently in clinical trials for solid tumors) and PD0325901 (a MEK inhibitor), potency was enhanced and there was a substantial increase in cell death. Analysis of downstream targets revealed a synergistic effect on target downregulation in the PI3K pathway. The drug combination was also evaluated in vivo in the orthotopic model. We found that it delayed tumor growth by increasing GBM cell apoptosis, resulting in significantly increased survival. Our results show that combined targeting of the PI3K and MAPK pathways can have a synergistic effect in glioblastoma, and that our primary cells were a valuable tool to predict the in vivo outcome. We also validated this new orthotopic model of GBM and showed that it is tractable for the assessment of potential therapeutic regimens for human GBM.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C11.

Citation Format: Rajaa El Meskini, Anthony Iacovelli, Alan Kulaga, Michelle Gumprecht, Philip L. Martin, Maureen L. Baran, Deborah B. Householder, Terry Van Dyke, Zoe Weaver Ohler. Combined inhibition of MEK and PI3 kinase signaling results in improved survival in a preclinical orthotopic model for human glioblastoma multiforme. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C11.

Abstract 1577: Subtype dependent carcinoma initiation by Rb tumor suppressor inactivation in multiple epithelial tissues

Carcinomas arise in a complex microenvironment consisting of multiple distinct epithelial lineages surrounded by mesenchymal cells. Of major importance is to understand the relationship among cell types, initiation event, and ultimate cancer outcome. Mouse models facilitate the prospective examination of early oncogenic events, which is not feasible in humans, permitting an analysis of epithelial subtype susceptibility. Since most solid tumors harbor aberrations in the pRb network, we assessed the susceptibility of epithelial subtypes expressing cytokeratin (K) 18 or K19 to the disruption of

Rb tumor suppression (Rb-TS) in vivo. Tumorigenesis could be initiated in either K18- or

K19-expressing cells. However, the susceptibility of epithelial tissues was subtype-dependent. K19 cells were more prone to hyperplasia and neoplasia than

K18 targeted cells. Given that a single genetic event was engineered, a small percentage of animals developed carcinoma/adenocarcinoma, providing the opportunity to define progression events via engineering or spontaneous evolution. To extend our analysis to a specific tissue, we employed a prostate-specific Cre line to target either K18- or K19-expressing prostate epithelial cells. Differential responses observed in the frequency and extent of premalignant hyperplastic lesions strongly supported the notion of cell type-dependent susceptibility to Rb-TS inactivation. Our data suggest that the tumorigenic consequences of a single initiation event are dictated by cellular subtype distinctiveness, underscoring the importance of the tumor cell of origin.

Citation Format: Yurong Song, Chunyu Yang, Wenqi Pan, Alisan Fathalizadeh, Lucy Lu, Debra Gilbert, T. Norene O'Sullivan, Diana C. Haines, Philip L. Martin, Terry Van Dyke. Subtype dependent carcinoma initiation by Rb tumor suppressor inactivation in multiple epithelial tissues. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1577. doi:10.1158/1538-7445.AM2013-1577

Göç, Ticaret ve Kalkınma: Meksika-ABD ve Türkiye-Avrupa Karşılaştırması Migration, trade, and development: Comparing Mexico-US and Turkey-Europe

Migration was the major relationship between Mexico and the US and Turkey and Western Europe for most of the past half century. Changes in both migrant-sending and –receiving countries aimed to substitute trade for migration. Mexico and Turkey have had roller-coaster economic growth trajectories, sometimes growing faster than other OECD countries and sometimes shrinking faster. There have been significant changes in Mexico and Turkey but, until more formal-sector jobs are created, especially young people leaving agriculture or joining the labour market may be candidates for migration.[IN TURKISH]Geçen yarım yüzyılda, göç Meksika- ABD, Türkiye ve Batı Avrupa arasındaki temel ilişki olagelmiştir. Göç-alan ve –veren ülkelerdeki değişimler göç yerine ticareti geçirme eğilimi taşımıştır. Meksika ve Türkiye inişli çıkışlı ekonomik büyüme görünümü sergilemişler, bazen diğer OECD ülkelerinden bile hızlı büyümüş, bazen ise daha hızlı küçülmüşlerdir. Meksika ve Türkiye’de çok temel değişimler yaşanmaktadır ve ancak daha fazla güvenli istihdam yaratılmadıkça tarımdan kopan genç işgücü ya da işgücüne yeni katılanlar göçün yeni adayları olacaktır. 

Temporal molecular and biological assessment of an erlotinib-resistant lung adenocarcinoma model reveals markers of tumor progression and treatment response

Patients with lung cancer with activating mutations in the EGF receptor (EGFR) kinase, who are treated long-term with tyrosine kinase inhibitors (TKI), often develop secondary mutations in EGFR associated with resistance. Mice engineered to develop lung adenocarcinomas driven by the human EGFR T790M resistance mutation are similarly resistant to the EGFR TKI erlotinib. By tumor volume endpoint analysis, these mouse tumors respond to BIBW 2992 (an irreversible EGFR/HER2 TKI) and rapamycin combination therapy. To correlate EGFR-driven changes in the lung with response to drug treatment, we conducted an integrative analysis of global transcriptome and metabolite profiling compared with quantitative imaging and histopathology at several time points during tumor progression and treatment. Responses to single-drug treatments were temporary, whereas combination therapy elicited a sustained response. During tumor development, metabolomic signatures indicated a shift to high anabolic activity and suppression of antitumor programs with 11 metabolites consistently present in both lung tissue and blood. Combination drug treatment reversed many of the molecular changes found in tumored lung. Data integration linking cancer signaling networks with metabolic activity identified key pathways such as glutamine and glutathione metabolism that signified response to single or dual treatments. Results from combination drug treatment suggest that metabolic transcriptional control through C-MYC and SREBP, as well as ELK1, NRF1, and NRF2, depends on both EGFR and mTORC1 signaling. Our findings establish the importance of kinetic therapeutic studies in preclinical assessment and provide in vivo evidence that TKI-mediated antiproliferative effects also manifest in specific metabolic regulation.

TMPRSS2- driven ERG expression in vivo increases self-renewal and maintains expression in a castration resistant subpopulation

Genomic rearrangements commonly occur in many types of cancers and often initiate or alter the progression of disease. Here we describe an in vivo mouse model that recapitulates the most frequent rearrangement in prostate cancer, the fusion of the promoter region of TMPRSS2 with the coding region of the transcription factor, ERG. A recombinant bacterial artificial chromosome including an extended TMPRSS2 promoter driving genomic ERG was constructed and used for transgenesis in mice. TMPRSS2-ERG expression was evaluated in tissue sections and FACS-fractionated prostate cell populations. In addition to the anticipated expression in luminal cells, TMPRSS2-ERG was similarly expressed in the Sca-1^hi/EpCAM⁺ basal/progenitor fraction, where expanded numbers of clonogenic self-renewing progenitors were found, as assayed by in vitro sphere formation. These clonogenic cells increased intrinsic self renewal in subsequent generations. In addition, ERG dependent self-renewal and invasion in vitro was demonstrated in prostate cell lines derived from the model. Clinical studies have suggested that the TMPRSS2-ERG translocation occurs early in prostate cancer development. In the model described here, the presence of the TMPRSS2-ERG fusion alone was not transforming but synergized with heterozygous Pten deletion to promote PIN. Taken together, these data suggest that one function of TMPRSS2-ERG is the expansion of self-renewing cells, which may serve as targets for subsequent mutations. Primary prostate epithelial cells demonstrated increased post transcriptional turnover of ERG compared to the TMPRSS2-ERG positive VCaP cell line, originally isolated from a prostate cancer metastasis. Finally, we determined that TMPRSS2-ERG expression occurred in both castration-sensitive and resistant prostate epithelial subpopulations, suggesting the existence of androgen-independent mechanisms of TMPRSS2 expression in prostate epithelium.

Perturbation of Rb, p53, and Brca1 or Brca2 cooperate in inducing metastatic serous epithelial ovarian cancer

The majority of human high-grade serous epithelial ovarian cancer (SEOC) is characterized by frequent mutations in p53 and alterations in the RB and FOXM1 pathways. A subset of human SEOC harbors a combination of germline and somatic mutations as well as epigenetic dysfunction for BRCA1/2. Using Cre-conditional alleles and intrabursal induction by Cre-expressing adenovirus in genetically engineered mice, we analyzed the roles of pathway perturbations in epithelial ovarian cancer initiation and progression. Inactivation of RB-mediated tumor suppression induced surface epithelial proliferation with progression to stage I carcinoma. Additional biallelic inactivation and/or missense p53 mutation in the presence or absence of Brca1/2 caused progression to stage IV disease. As in human SEOC, mice developed peritoneal carcinomatosis, ascites, and distant metastases. Unbiased gene expression and metabolomic profiling confirmed that Rb, p53, and Brca1/2-triple mutant tumors aligned with human SEOC, and not with other intraperitoneal cancers. Together, our findings provide a novel resource for evaluating disease etiology and biomarkers, therapeutic evaluation, and improved imaging strategies in epithelial ovarian cancer.

Abstract A42: Sensitivity and resistance to a p-AKT inhibitor in an erlotinib-sensitive model for lung cancer

Activating mutations in EGFR, such as the L858R mutation, are effective predictors of response to EGFR tyrosine kinase inhibitor (TKI) therapy. While most patients initially respond to EGFR TKIs, the majority relapse within 6-12 months, underscoring the importance of identifying therapies that enhance and prolong EGFR TKI activity in patients. Agents targeting additional nodes in the EGFR pathway have the potential to overcome such resistance but single-agent activity must be understood first. We utilized mice engineered to develop erlotinib-sensitive lung adenocarcinomas driven by the human EGFR L858R mutation to evaluate the efficacy of a p-AKT inhibitor, MK-2206, currently in clinical trials for a variety of solid tumor malignancies. MK-2206 concentration and target activity were assessed in short-term PK/PD studies in both the lungs and blood of tumor-bearing mice. MK-2206 was then evaluated in an efficacy study using a twice-weekly dosing regimen, both as a single agent and in combination with other TKIs. MK-2206 alone resulted in tumor regression or tumor growth inhibition in ∼50% of the mice, but exhibited greater efficacy in combination with other upstream pathway inhibitors. Temporal evaluation of tumor growth inhibition indicated that MK-2206 was most effective at early time points and did not produce a sustained pathway and growth response as treatment continued. Analysis of gene expression changes in mice treated with MK-2006 alone vs. MK-2206 in combination with EGFR TKIs highlighted the pathways perturbed by both drugs.

Abstract B28: TMPRSS2- driven ERG in primary prostate epithelium demonstrates castration-resistant expression and expands a unique population of progenitor cells

It has become increasingly appreciated that recurrent genomic rearrangements contribute to the genesis of solid tumors. The genomic rearrangement of the Ets transcription factor, Ets related gene (ERG), with the promoter of the highly expressed Transmembrane protease serine 2 (TMPRSS2) gene, has been demonstrated in 20-65% of prostate adenocarcinoma precursor lesions, implying that ERG may contribute a function selected early in cancer formation. However, the functional role of ERG in developing prostate cancer is unclear. This study utilized bacterial artificial chromosome transgenesis, to produce a mouse model that recapitulates the genetic regulatory features of the genomic TMPRSS2-ERG translocation, where exon 1 and 2 of TMPRSS2 is fused to the region downstream of ERG exon 8. This model allows mechanistic investigations into the function and regulation of expression for TMPRSS2 promoter-driven ERG in the earliest initiating phase of tumorigenesis.

Using QRT-PCR, TMPRSS2-ERG was expressed in the progenitor containing, Sca-1hi fraction of FACS-separated primary prostate cells. In addition, the fusion gene functioned to expand a unique subpopulation of prostate epithelial progenitors when compared to wild type, as demonstrated by serially passaged in vitro sphere forming assays. Androgen regulation of TMPRSS2 has been shown in a limited number of androgen receptor positive luminal prostate cancer cell lines. In this study, TMPRSS2-ERG expression demonstrated a significant castration-resistant component, suggesting mechanisms of AR-independent transcriptional regulation for the TMPRSS2 promoter in the setting of primary prostate epithelial cells. Introduction of the TMPRSS2-ERG fusion alone did not result in histological change, where prostate sections from mice up to 15 months of age were examined. However, the functionality of the model was shown as TMPRSS2-ERG synergized with heterozygous Pten loss to promote PIN. No apparent genetic interaction was observed between TMPRSS2-ERG and Nkx3.1 loss.

These studies demonstrate the potential for androgen independent TMPRSS2-ERG expression in primary prostate epithelium and show that TMPRSS2-ERG expression promotes increased self-renewal of prostate progenitors. These data support a model whereby TMPRSS2-ERG regulates progenitor cell de-differentiation or survival, including within a population of castration-resistant progenitors.

Citation Format: Orla M. Casey, Paul G. Hynes, Lei Fang, Wassim G. Abou-Kheir, Philip L. Martin, Heather S. Tillman, Hibah O. Awwad, Luhua Zhang, Kathleen Kelly. TMPRSS2- driven ERG in primary prostate epithelium demonstrates castration-resistant expression and expands a unique population of progenitor cells [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B28.

Characterizing the contribution of stem/progenitor cells to tumorigenesis in the Pten-/-TP53-/- prostate cancer model

Loss of PTEN is one of the most common mutations in prostate cancer, and loss of wild-type TP53 is associated with prostate cancer progression and castrate resistance. Modeling prostate cancer in the mouse has shown that while Pten deletion in prostate epithelial cells leads to adenocarcinoma, combined loss of Pten and TP53 results in rapidly developing disease with greater tumor burden and early death. TP53 contributes significantly to the regulation of stem cell self-renewal, and we hypothesized that loss of Pten/TP53 would result in measurable changes in prostate cancer stem/progenitor cell properties. Clonogenic assays that isolate progenitor function in primary prostate epithelial cells were used to measure self-renewal, differentiation, and tumorigenic potential. Pten/TP53 null as compared with wild-type protospheres showed increased self-renewal activity and modified lineage commitment. Orthotopic transplantation of Pten/TP53 null cells derived from protospheres produced invasive Prostatic Intraepithelial Neoplasia (PIN)/adenocarcinoma, recapitulating the pathology seen in primary tumors. Pten/TP53 null progenitors relative to wild type also demonstrated increased dependence on the AKT/mammalian target of rapamycin complex 1 (mTORC1) and androgen receptor (AR) pathways for clonogenic and tumorigenic growth. These data demonstrate roles for Pten/TP53 in prostate epithelial stem/progenitor cell function, and moreover, as seen in patients with castrate-resistant prostate cancer, suggest for the involvement of an AR-dependent axis in the clonogenic expansion of prostate cancer stem cells.

Capacity for resolution of Ras-MAPK-initiated early pathogenic myocardial hypertrophy modeled in mice

Activation of Ras signaling in cardiomyocytes has been linked to pathogenic myocardial hypertrophy progression and subsequent heart failure. Whether cardiomyopathy can regress once initiated needs to be established more fully. A 'tet-off' system was used to regulate expression of H-Ras-G12V in myocardium to examine whether Ras-induced pathogenic myocardial hypertrophy could resolve after removal of Ras signaling in vivo. Ras activation at weaning for 2 wk caused hypertrophy, whereas activation for 4 to 8 wk led to cardiomyopathy and heart failure. Discontinuing H-Ras-G12V transgene expression after cardiomyopathy onset led to improved survival and cardiomyopathy lesion scores, with reduced heart:body weight ratios, demonstrating the reversibility of early pathogenic hypertrophy. Activation of Ras and downstream ERK 1/2 was associated with elevated expression of proliferating cell nuclear antigen and cyclins B1 and D1, indicating cell-cycle activation and reentry. Coordinate elevation of broad-spectrum cyclin-dependent kinase inhibitors (p21, p27, and p57) and Tyr15 phosphorylation of cdc2 signified the activation of cell-cycle checkpoints; absence of cell-cycle completion and cardiomyocyte replication were documented by using immunohistochemistry for mitosis and cytokinesis markers. After resolution of cardiomyopathy, cell-cycle activators and inhibitors examined returned to basal levels, a change that we interpreted as exit from the cell cycle. Cardiac cell-cycle regulation plays a role in recovery from pathogenic hypertrophy. The model we present provides a means to further explore the underlying mechanisms governing cell-cycle capacity in cardiomyocytes, as well as progression and regression of pathogenic cardiomyocyte hypertrophy.

Abstract 3241: Multipotential PTEN−/− p53−/− prostate tumor initiating cells give rise to adenocarcinoma which displays epithelial-to-mesenchymal transition, metastasis, and androgen independent growth

Determining the cell lineage and differentiation potential of tumor initiating cells is fundamental to understanding mechanisms of progression and metastasis. We describe the differentiative, tumorigenic, and metastatic properties of primary, transplanted secondary, and clonally-derived tumors in a model of prostate cancer initiated by prostate epithelial cell specific deletion of the tumor suppressors, PTEN and p53. Although adenocarcinoma is the majority tumor type that develops in this mouse model, other histological tumor types, including a late developing sarcomatoid carcinoma were observed. The heterogeneity displayed in transgenic mouse prostate tumors may be due to the transformation of multiple lineage specific tumor initiating cells, or a common tumor progenitor/stem cell capable of plasticity in differentiation potential. Orthotopic transplantation of PTEN−/− p53−/−prostate carcinoma cells was undertaken to determine whether a single tumor initiating cells is capable of giving rise to the diversity of tumor phenotypes observed in the parental prostate carcinoma. Direct orthotopic transplantation of mixed populations of PTEN−/− p53−/− tumor cells favored the development of adenocarcinomas, while transplantation of cells grown as protospheres in matrigel favored the development of basal/squamous carcinomas. This indicates a developmental plasticity in transplantable tumor initiating cells that can be influenced by extracellular matrix components. Transplantation of clonal cell lines that were derived from orthotopic carcinomas produced adenocarcinomas with lesser amounts basal/squamous carcinoma with one line undergoing EMT to form sarcomatoid carcinomas. Lung and lymph node metastases were common. Tumor growth, metastasis, and response to androgen deprivation were assayed with in-vivo bioluminescent imaging. The orthotopic tumors recapitulated the diversity of tumor phenotypes observed in the probasin-cre, PTEN fl/fl p53 fl/fl transgenic donor mouse including: adenocarcinoma, spindle cell carcinoma, urothelial carcinoma, and basal/squamous carcinoma. In a pattern that mimics a phenotype observed in metastatic human prostate carcinoma, CK8+ adenocarcinomas displayed heterogeneous labeling for the neuroendocrine marker synaptophysin. Our data suggests that a multi-potential CK8+/CK5+ tumor stem cell can be a progenitor for CK8+ adenocarcinoma.

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 3241.

Thermal stability of the thermoluminescence trap structure of bentonite

This work reports about the thermal stability of the blue thermoluminescence (TL) of a well-characterised natural bentonite from Almeria (Spain). The main interest of this clay, mainly composed of montmorillonite, is because of its application in the field of high-level radioactive waste (HLW) repository in deep-lying rocks. As observed in other aluminosilicates, bentonite exhibits a very complex structure of the emission spectra based on a wide broad maximum peaked at approximately 265 degrees C that can be associated to physico-chemical processes such as dehydroxylation processes, consecutive breaking linking of bonds, formation of hydrolysed ions and redox reactions. The thermal stability tests performed at different temperatures confirm a continuum in the distribution of traps. Hence, the glow curve analysis methods commonly used for synthetic materials based on single discrete traps cannot be applied for this material and the kinetic parameters were fitted assuming an exponential distribution of trapped electrons.

Mexican Migration to the United States: The Effect of NAFTA

Migration has more often been the source of conflict than cooperation in Mexico‐US relations. The US accepts immigrants from and trades with many nations, but virtually all Mexican migrants head for the US, and most Mexican trade is with the US. The North American Free Trade Agreement (NAFTA), which went into effect on January 1, 1994, was expected to convert this migration relationship into a trade and investment relationship. Trade may eventually be a substitute for migration between Mexico and the US, but during the 1990s there was a hump or increase in Mexico‐US migration.

Incorporation of bovine bone marrow stromal cells into porcine foetal tissues after xenotransplantation

Bovine bone marrow stromal cells (BMSCs) were injected into the liver of foetal pigs at about 40 days of gestation to test whether these cells could populate developing tissue, and if so, which ones. Approximately 40 days after injection, the foetuses were harvested and tissue sections from many areas of the body were analysed for the presence of bovine cells using two different methods. First, using PCR, bovine repetitive DNA was found to be present in DNA extracted from foetal pig tissues. Secondly, using oligonucleotide primed in situ synthesis (PRINS), the in situ presence of bovine cells was found within porcine tissue sections. PRINS-labelled cells were found within cartilage, perichondrium, connective tissue and smooth muscle. These data suggest that bovine BMSCs integrate throughout the foetal pig.

Low incidence of Epstein-Barr virus-associated posttransplantation lymphoproliferative disorders in 272 unrelated-donor umbilical cord blood transplant recipients

Umbilical cord blood (UCB) is being increasingly used for transplantation, but the ability of neonatal T cells to regulate Epstein-Barr virus (EBV)-associated lymphoproliferation is unknown. Because UCB transplantation (UCBT) is associated with a relatively low infused dose of donor T cells, frequent donor-recipient HLA disparity, and use of antithymocyte globulin during conditioning, we hypothesized that the risk of EBV-associated posttransplantation lymphoproliferative disorders (EVB-PTLD) after UCBT may be increased. To investigate the incidence of EBV-PTLD after UCBT, we analyzed 272 unrelated-donor UCBTs performed from August 1993 to December 1999 at Duke University Medical Center and the University of Minnesota. Five cases of EBV-PTLD were identified, with a cumulative incidence of 2% (95% confidence interval, 0.3%-3.7%) at 2 years. EBV-PTLD affected UCB recipients aged 1 to 49 years (median, 8 years), with 4 patients undergoing transplantation for leukemia and 1 for immunodeficiency. Patients received UCB grafts that were HLA matched (n = 1) or mismatched at 1 (n = 1) or 2 (n = 3) HLA loci. Diagnoses occurred at 4 to 14 months (median, 6 months) after UCBT, with 4 of 5 patients having preceding grade II to IV acute graft-versus-host disease and 1 being diagnosed at autopsy. Treatment of 4 patients consisted of withdrawal of immunosuppressive treatment and administration of rituximab, with 2 of 4 patients responding. Thus, the incidence of EBV-PTLD after unrelated-donor UCBT appears similar to that observed after transplantation using unrelated bone marrow (BM) and compares favorably with unrelated-donor T-cell-depleted BM transplantation. Because adoptive immunotherapy with donor lymphocytes is not an available option for recipients of unrelated-donor UCBT, new therapeutic strategies are needed, and rituximab appears promising.

Human herpesvirus 6 limbic encephalitis after stem cell transplantation

Central nervous system complications are common in stem cell transplant recipients, but selective involvement of the medial temporal area is unusual. The 5 patients reported here presented after stem cell transplantation with increased hippocampal T2 signal on magnetic resonance imaging and increased hippocampal glucose uptake on [F-18]fluorodeoxyglucose-positron emission tomography (FDG-PET) associated with short-term memory loss, insomnia, and temporal lobe electrographic seizure activity. The initial scalp electroencephalograms (EEGs) failed to detect seizure activity in these patients, although the memory dysfunction along with the magnetic resonance imaging and FDG-PET findings suggested subcortical seizure activity. However, extended EEG monitoring revealed repetitive temporal lobe electrographic seizure activity. Follow-up MRIs in 2 patients and postmortem findings on 1 patient suggested that hippocampal sclerosis had developed following the clinical syndrome. Cerebrospinal fluid studies revealed the presence of human herpesvirus 6, variant B, DNA in all of 3 patients who had lumbar punctures. Immunohistochemical staining for the P41 and P101 human herpesvirus 6 protein antigens showed numerous immunoreactive astrocytes and neurons in the hippocampus of 1 of the patients who died from other causes. Because of its subtle clinical presentation, this syndrome may be underrecognized, but can be diagnosed with appropriate magnetic resonance imaging techniques, EEG monitoring, and cerebrospinal fluid viral studies.

Xenotransplantation of bovine bone marrow stromal cells into pig fetuses: incorporation into skeletal muscle

Bone marrow stromal cells are multipotent and have been shown to differentiate into a wide variety of mesenchymal cell types in vivo. In this study we tested the ability of bovine bone marrow stromal cells to contribute to the development of porcine skeletal muscle tissue. Fetal pigs were injected early in gestation with bone marrow stem cells originating from slaughtered steers. After approximately forty days of development the fetuses were harvested and sections of their skeletal muscle were analyzed for the presence of bovine cells. PCR was used to detect bovine DNA present in DNA extracted from the fetal pig skeletal muscle. We also used a PRINS (Oligonucleotide Primed In- Situ Synthesis) protocol to confirm the presence of bovine cells within the porcine skeletal muscle tissue sections. The results of both assays indicate that bovine bone marrow stromal cells can participate in the development of porcine skeletal muscle. This study helps to demonstrate the potential that bone marrow stromal cells have to contribute to advances in animal biotechnology and medicine.

Graft-versus-leukemia-induced complete remission following unrelated umbilical cord blood transplantation for acute leukemia

A 15-year-old female received an unrelated three of six HLA antigen matched umbilical cord blood (UCB) transplant for refractory, relapsed T-cell ALL. Conditioning consisted of TBI, melphalan, and anti-thymocyte globulin (ATG), with cyclosporin A (CsA) and solumedrol for GVHD prophylaxis. She engrafted and a day 34 bone marrow aspirate showed 100% donor cells and no evidence of leukemia. The post-transplant course was complicated by mild grade I acute GVHD involving skin, and limited chronic GVHD of the gut which resolved with the addition of 1 mg/kg/day of steroids to her CsA prophylaxis. One hundred and ninety days after transplantation the patient developed pancytopenia and was subsequently found to have a leukemic relapse. Immunosuppression was discontinued and she was started on G-CSF and erythropoietin. Moderate skin and gut GVHD developed which was treated with both topical and low-dose oral steroids. Over the next few weeks she became transfusion independent and a follow-up bone marrow aspirate showed complete remission. She continued in complete remission for 4 months, at which time localized leukemic relapse was found in a soft tissue breast mass in spite of continued bone marrow remission. While the patient ultimately died of progressive disease, this case demonstrates that mismatched UCB in conjunction with G-CSF is capable of generating a GVL effect that can induce a complete remission.

Adenosine agonists for the prevention of restenosis?

Balloon angioplasty involves the simultaneous activation of platelets and neutrophils. Activated platelets release mitogenic substances that cause smooth muscle cell proliferation and thereby contribute to restenosis. Activated neutrophils activate platelets and activated platelets activate neutrophils. Therefore the simultaneous activation of both cell types may be responsible for the exaggerated repair mechanisms resulting in restenosis of coronary blood vessels. Adenosine inhibits neutrophil activation, platelet activation and smooth muscle cell proliferation and stimulates endothelial cell proliferation predominantly through activation of A2A-receptors. Adenosine and A2A-selective agonists may be useful in the prevention of restenosis following balloon angioplasty.

Toxicity, pharmacology and feasibility of administration of PEG-L-asparaginase as consolidation therapy in patients undergoing bone marrow transplantation for acute lymphoblastic leukemia

We attempted to administer PEG-L-asparaginase (PEG-L-A) following hematologic recovery to 38 patients undergoing autologous or allogeneic marrow transplantation for acute lymphoblastic leukemia (ALL). Twenty-four patients (12 of 22 receiving allogeneic and 12 of 16 receiving autologous transplants) received between one and 12 doses of PEG-L-A, including nine who completed the planned 12 doses of therapy. The toxicities encountered were similar to those observed in non-transplanted patients undergoing therapy with PEG-L-A and included allergic reactions, pancreatitis, weight loss, hypoalbuminemia, and low levels of anti-thrombin III. Of the 24 who received the drug, eight remain in remission. Of 12 patients in second remission at the time of transplantation who received PEG-L-A, five of seven who received allogeneic and two of five who received autologous transplants remain in remission, 16+ to 46+ months from transplant. While PEG-L-A could be administered to most of the patients undergoing marrow transplantation for ALL, most patients either relapsed while receiving the drug or developed toxicities which resulted in abbreviated courses. At this time, we cannot recommend PEG-L-A as single agent, post-BMT chemotherapy.

Maternal selenium levels and sudden infant death syndrome (SIDS)

BACKGROUND

The possibility is tested that low anti-oxidant status and/or low levels of selenium (Se) might predispose to Sudden Infant Death Syndrome (SIDS).

AIM

This study was undertaken to collect evidence on the Se status of pregnant and non-pregnant women and newborn babies and to establish whether babies who later died of cot death had significantly divergent levels of blood Se at birth.

METHODOLOGY

Aliquots of blood were collected from all newly pregnant mothers in Tasmania and from the cords of all newborn babies. These were analysed for Se and glutathione peroxidase (GPx) content and compared by season and with non-pregnant, age standardised blood donors in three areas of Tasmania and three mainland Australian States.

RESULTS

Cot death babies' cordbloods were not significantly different in Se or GPx-status, in this small sample, from those of other babies, nor was a seasonal variation in these parameters demonstrated among 390 randomly selected Tasmanian mothers. Mothers-to-be showed a decrease in enzyme levels during pregnancy and Tasmanian blood donors had significantly lower levels than donors from other States.

CONCLUSION

While no evidence can safely be drawn about a relationship between Se or GPx-status and SIDS, this study provides base level measures for populations showing that Tasmanian residents have low levels of these anti-oxidants.