Survivin in lung cancer: a potential target for therapy and prevention-a narrative review

Background and Objective

A versatile biomarker, survivin, is highly expressed in proliferating cells of multiple cancers in humans and animals. It is an apoptosis-regulating protein, engaging in a cascade of reactions that involve several other genes and protein interactions. Currently, researchers are investigating its therapeutic potential due to the evidence linking its overexpression to advanced-stage lung cancer. This review is centered around examining survivin-related molecular mechanisms and its therapeutic role specifically in lung cancer. Our objective is to discuss the role of survivin in prognosis and treatment response, shedding light on immune-targeted therapies, as well as outlining future directions for survivin-based vaccines in lung cancer.

Methods

The PubMed database and the United States National Library of Medicine search engine at the National Institutes of Health were searched on 24 August 2023 to identify published research studies. Searching "((((((airway [Title/Abstract]) OR (lung [Title/Abstract])) OR (pulm[Title/Abstract])) OR (bronch[Title/Abstract])) OR (nslc[Title/Abstract])) AND (((cancer[Title/Abstract]) OR (carcino[Title/Abstract])) OR (oncol[Title/Abstract]))) AND (survivin[Title/Abstract])" gave 728 results. After screening the title and abstracts and excluding the review articles 168 titles were shortlisted and full text studied. The discussions are added to relevant sections.

Key Content and Findings

Survivin is a cell cycle-dependent, inhibitor of apoptosis protein that contributes to carcinogenesis, tumor vascularization, metastasis, and treatment resistance. Several treatments that impact survivin either directly or indirectly have been reported as effective in treating lung cancer. Immunity-based therapy, a novel approach known for its targeted nature and minimal side effects, is currently under investigation for lung cancer treatment. Emerging survivin-centered vaccines exhibit promising attributes in terms of safety, effectiveness, and ability to stimulate an immune response. These factors point towards a significant potential for advancing the future of lung cancer prevention and enhancing overall survival rates.

Conclusions

Nuclear survivin is a potential biomarker for advanced non-small cell lung cancer. It plays a role in determining drug responsiveness and is found to be significantly elevated in cases of resistance to chemotherapy. Multiple compounds and immunization strategies have been identified to impact lung cancer cells; however, they are currently in the early stages of phase I or phase II clinical trials. The substantial promise of survivin-based immunogenicity-focused treatments warrants in-depth investigation and exploration.

Novel Macromolecular and Biobased Flame Retardants Based on Cellulose Esters and Phosphorylated Sugar Alcohols

The increasing demand to provide sustainably produced plastic materials requires, a.o., the development of biobased flame retardants (FRs) for applications where flame retardancy is essential. To meet those challenging new sustainability requirements, a set of novel phosphorus-containing cellulose esters were synthesized by an efficient two-step procedure. In the first step, cellulose was treated with acrylic anhydride to synthesize acrylate-functionalized cellulose esters-more specifically, cellulose acrylate butyrate (CeAcBu) and propionate (CeAcPr). Subsequently, phosphorylated anhydro erythritol (PAHE), synthesized from the sugar alcohol erythritol, was added to the acrylate-functionalized cellulose esters via Phospha-Michael addition. For comparison a cellulose ester based on 6H-Dibenzo[c,e][1,2]oxaphosphorin-6-on (DOPO) was prepared analogously. The acrylate-functionalized cellulose esters and novel FRs were characterized by NMR spectroscopy. TGA investigations of PAHE-functionalized CeAcBu revealed an onset temperature of decomposition (2% mass loss) of approx. 290 °C. The novel PAHE-based FR was incorporated into a polypropylene-polyethylene copolymer (PP-co-PE) together with poly-tert-butylphenol disulfide (PBDS) (8 wt.%/2 wt.%) as a synergist. The PP-PE samples achieved V2 classification in the UL 94 V test. In addition, specimens of a rapeseed oil-based polyamide containing PAHE-functionalized CeAcBu at 20 wt.% loading yielded a V2 rating with short burning times.

OTME-21. The role of Glioblastoma associated mesenchymal stem cells in immune suppression

Glioblastoma (GBM) is an aggressive brain cancer, with an overall survival of 14.6 months. The tumor microenvironment in GBM plays major roles in immunosuppression and modulation of the response to therapies. GBM patients with higher levels of mesenchymal stem like cells (G-MSC) show poor overall survival as compared to patients with no/lower G-MSC levels. Our lab found that levels of G-MSC corelate with CD4+ T cells in humans and murine models of GBM, and with immunosuppressive molecules like PTGS2, the gene for cyclooxygenase 2. To investigate the mechanism by which G-MSCs promote immunosuppression, we isolated G-MSCs from an orthotopic mouse model of GBM and subjected them to RNASeq analysis to obtain an unbiased picture of transcriptomic changes occurring upon activation. We identified changes in multiple immune modulating pathways involving antigen presentation, leukocyte migration and activation, and immune checkpoints. Our findings indicate that G-MSCs represent a key immune modulating faction in the microenvironment. Further dissection of the role of these cells in immune modulation will aid us in understanding the biology of the brain tumor microenvironment and identifying potential combination therapies.

TAMI-63. GLIOBLASTOMA ASSOCIATED MESENCHYMAL STEM LIKE CELLS (G-MSC) WHICH INFILTRATE TUMORS IN HUMAN AND MOUSE ARE STRONGLY ASSOCIATED WITH IMMUNOSUPPRESSION

Glioblastoma (GBM) is the most aggressive form of brain cancer with an overall survival (OS) less than 16 months. Glioblastoma associated mesenchymal stem like cells (G-MSC) were identified in human patient samples, and higher presence of these cells in patient samples co-relates with lower overall survival. Our lab and others have also identified these cells in orthotopic GL261 glioblastoma murine models. We hypothesize that infiltration of G-MSC plays a key role in creating the highly immunosuppressive environment seen in GBMs. In order to investigate this, we utilized data from the TCGA database to stratify patients into two groups, showing higher or lower expression of the G-MSC markers (CD73, CD90, CD105). Patients expressing higher levels of G-MSC markers showed higher expression of CD4+ cells, as compared to patients with lower G-MSC marker expression. Further, patients with higher G-MSC markers showed high levels of PTGS2, the gene encoding cyclooxygenase 2 (COX2), a known tumor growth promoting and immunosuppressive molecule. We further investigated CD4+ T cell infiltration using GL261 orthotopic implants and observed that CD4+ T cells positively corelated with levels of G-MSC in these tumors. Our studies indicate that levels of G-MSC co-relate with immune cell infiltration and the expression of immunosuppressive factors such as COX2, underlining the importance of these cells in immunosuppression-driven resistance to therapy. These studies will be later utilized to develop rationale combination therapies to improve the overall survival in GBM.

CTIM-10. PHASE II STUDY OF PEMBROLIZUMAB PLUS SurVaxM FOR GLIOBLASTOMA AT FIRST RECURRENCE

BACKGROUND

Pembrolizumab is a potent humanized immunoglobulin G4 monoclonal antibody with high specificity of binding to the programmed cell death 1 (PD-1) receptor, thus inhibiting its interaction with programmed cell death ligand 2 (PD-L2). Survivin is a 16.5 kDa intracellular protein that belongs to the inhibitor of apoptosis protein (IAP) family. It acts in concert with the mitotic spindle apparatus to regulate cell division and localizes to the spindle microtubule organizing center (MTOC) during the G2/M phase of cell cycle progression. Survivin has also been shown to modulate the function of a number of terminal effector cell death proteases (caspases) leading to an inhibition of apoptosis.

METHODS

This is a Phase II study of two arms in patients with recurrent glioblastoma. Arm A is patients with first recurrence of glioblastoma who have failed prior chemotherapy and radiation but have not received any immunotherapy. Arm B is an exploratory arm of 10 patients who have failed prior anti-PD1 therapy. The ongoing study is a phase II clinical study with a 10 patient, toxicity run-in. All patients will receive the study drug combination consisting of SurVaxM and pembrolizumab with no randomization, stratification or dose escalation.

RESULTS

So far ten patients have been enrolled on the study as safety run in. Primary endpoint is Progression free survival at 6 months. Safety and tolerability of Pembrolizumab and SurVaxM, Response rates of Pembrolizumab and SurVaxM determined using RANO criteria are secondary endpoints. Additional secondary endpoints include Overall survival and Progression Free survival Exploratory endpoints include Cellular and humoral immune responses during concurrent administration of Pembrolizumab and SurVaxM.

CONCLUSION

This is an ongoing clinical trial.

The Presence of Survivin on B Cells from Myasthenia Gravis Patients and the Potential of an Antibody to a Modified Survivin Peptide to Alleviate Weakness in an Animal Model

Myasthenia gravis (MG) is an autoimmune disease in which Abs target neuromuscular junction proteins, in particular the acetylcholine receptor. We previously identified the antiapoptotic protein survivin in the autoreactive B cells and plasma cells of MG patients. To further define the role of survivin in MG, we have assessed PBMCs from 29 patients with MG and 15 controls. We confirmed the increased expression of survivin in CD20⁺ lymphocytes from MG patients compared with controls. Furthermore, the CD20⁺ population of cells from MG patients contained a higher percentage of extracellular survivin compared with controls. The analysis of CD4⁺ cells showed an increased percentage of intracellular survivin in MG patients compared with controls, whereas the extracellular survivin CD4⁺ percentage was unaffected. In an experimental mouse model of MG, we assessed the therapeutic potential of an Ab raised to a modified survivin peptide but cross-reactive to survivin. Ab treatment reduced disease severity, lowered acetylcholine receptor-specific Abs, and decreased CD19⁺ survivin⁺ splenocytes. The ability to target survivin through Ab recognition of autoreactive cells offers the potential for a highly specific therapeutic agent for MG.

Abstract 5873: Identification of novel BIRC5/survivin splice variants in cancer

Background: BIRC5/survivin is highly expressed in cancer cells and represents a promising therapeutic target. In order to complete a comprehensive survey of its splice variants, we applied a direct RT-PCR approach as well as next generation sequencing (NGS) to tumor cell cDNAs. We have identified 10 novel splice junctions and three novel splice variants of survivin.

Methods: Survivin transcripts were amplified from A1207 (glioblastoma) HeLa (cervical adenocarcinoma) and U87 (glioblastoma) cDNAs. For manual identification of splice forms, individual products were subcloned into TOPO vector and sequenced. For NGS analysis, RT-PCR products used to generate libraries which were subjected to sequencing, after which resulting reads were mapped against the human reference genome and assembled by Trinity.

Results: Survivin RT-PCR products from A1207 cDNA were isolated and selected for TOPO cloning/sequencing. Of seventeen clones, the canonical isoform was represented by 4, and known variants including Δex3, 2B and 3B were represented by 5. Two novel sequences were identified: 1) 2B/Δex3, which contains a 68 bp shuffled exon 4/3 segment between exons 3 and 4 plus the 2B insert, and 2) 4B, in which exon 4 is extended by 27 bp at its 5' end. Both of these transcripts are predicted to encode full-length proteins: 2B/Δex3 contains the 23 aa 2B insert plus Δex3's unique C-terminus; 4B contains a novel 9 aa motif embedded in survivin's C-terminal alpha helix. RT-PCR products from A1207, HeLa and U87 templates subjected to NGS yielded five full-length BIRC5 contigs, including the canonical isoform, Δex3, 2B, 3B, and the predicted variant 2B/3B. To identify novel splice junctions, sequences were searched excluding canonical exon boundaries. The resulting 151 reads represented 10 novel exon junctions, among which the greatest proportion consisted of exon 1 and 3 (71 reads, 47%), or an extension of exon 2B by 32 bp at its 3' end (35 reads, 23%). Two variants contained the extended version of exon 4 seen in isoform 4B. A primer annealing within exon 4B's unique 27 bp was subsequently used for RT-PCR to validate the expression of the full-length isoform in HeLa, U87, A1207 and HEK293T cells.

Conclusions: We have identified multiple novel splice variants of survivin, including Δex3/2B, 4B, and Δex3/4B. Proteins encoded by these transcripts potentially have pro- or anti-oncogenic functions, and further studies are needed to delineate their role in survivin biologies.

Citation Format: Sheila Figel, Meaghan Birkemeier, Jesse Luce, Prashant Singh, Jianmin Wang, Cheryl Frank, Sanam Dharma, Emma Steinmetz, Michael Ciesielski, Robert Fenstermaker. Identification of novel BIRC5/survivin splice variants in cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5873.

Exploring the role of survivin in neuroendocrine neoplasms

Neuroendocrine tumors (NETs) are a heterogenous group of tumors. While most NETs have excellent prognosis, certain subsets have aggressive biology and have limited treatment options. We explored the role of survivin in NET as a prognostic and potentially therapeutic marker. Tissue microarrays of 132 patients were stained for survivin using immunohistochemistry (IHC) and correlated with outcomes. Using genomic database, we then correlated survivin (BIRC5) mRNA expression with radiosensitivity index (RSI) in 52 samples of NET. Finally, we studied the effect of radiation on survivin expression in human cell lines and the impact of knock-down of BIRC5 on cell proliferation and radiation sensitivity. We found that survivin positivity by IHC correlated with a shorter survival (overall survival 8.5 years vs. 18.3 years, p < 0.001). There was a positive correlation between BIRC5 expression and RSI (r = 0.234, p < 0.0001). Radiation exposure increased BIRC5 gene expression in a human carcinoid cell line. Knockout of BIRC5 using siRNA reduced proliferation of neuroendocrine cells but did not increase radiation sensitivity. We conclude that survivin expression in NET correlates with an inferior survival and survivin expression in human carcinoid cell lines increases after exposure to ionizing radiation.

Dietary Protein Restriction Reprograms Tumor-Associated Macrophages and Enhances Immunotherapy

PURPOSE

Diet and healthy weight are established means of reducing cancer incidence and mortality. However, the impact of diet modifications on the tumor microenvironment and antitumor immunity is not well defined. Immunosuppressive tumor-associated macrophages (TAMs) are associated with poor clinical outcomes and are potentially modifiable through dietary interventions. We tested the hypothesis that dietary protein restriction modifies macrophage function toward antitumor phenotypes.

EXPERIMENTAL DESIGN

Macrophage functional status under different tissue culture conditions and in vivo was assessed by Western blot, immunofluorescence, qRT-PCR, and cytokine array analyses. Tumor growth in the context of protein or amino acid (AA) restriction and immunotherapy, namely, a survivin peptide-based vaccine or a PD-1 inhibitor, was examined in animal models of prostate (RP-B6Myc) and renal (RENCA) cell carcinoma. All tests were two-sided.

RESULTS

Protein or AA-restricted macrophages exhibited enhanced tumoricidal, proinflammatory phenotypes, and in two syngeneic tumor models, protein or AA-restricted diets elicited reduced TAM infiltration, tumor growth, and increased response to immunotherapies. Further, we identified a distinct molecular mechanism by which AA-restriction reprograms macrophage function via a ROS/mTOR-centric cascade.

CONCLUSIONS

Dietary protein restriction alters TAM activity and enhances the tumoricidal capacity of this critical innate immune cell type, providing the rationale for clinical testing of this supportive tool in patients receiving cancer immunotherapies.

Tasquinimod modulates suppressive myeloid cells and enhances cancer immunotherapies in murine models

A major barrier for cancer immunotherapy is the presence of suppressive cell populations in patients with cancer, such as myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM), which contribute to the immunosuppressive microenvironment that promotes tumor growth and metastasis. Tasquinimod is a novel antitumor agent that is currently at an advanced stage of clinical development for treatment of castration-resistant prostate cancer. A target of tasquinimod is the inflammatory protein S100A9, which has been demonstrated to affect the accumulation and function of tumor-suppressive myeloid cells. Here, we report that tasquinimod provided a significant enhancement to the antitumor effects of two different immunotherapeutics in mouse models of cancer: a tumor vaccine (SurVaxM) for prostate cancer and a tumor-targeted superantigen (TTS) for melanoma. In the combination strategies, tasquinimod inhibited distinct MDSC populations and TAMs of the M2-polarized phenotype (CD206(+)). CD11b(+) myeloid cells isolated from tumors of treated mice expressed lower levels of arginase-1 and higher levels of inducible nitric oxide synthase (iNOS), and were less immunosuppressive ex vivo, which translated into a significantly reduced tumor-promoting capacity in vivo when these cells were coinjected with tumor cells. Tumor-specific CD8(+) T cells were increased markedly in the circulation and in tumors. Furthermore, T-cell effector functions, including cell-mediated cytotoxicity and IFNγ production, were potentiated. Taken together, these data suggest that pharmacologic targeting of suppressive myeloid cells by tasquinimod induces therapeutic benefit and provide the rationale for clinical testing of tasquinimod in combination with cancer immunotherapies.

Orthoamide, LV [1]. C7H7N3O6 - Tris(diformylamino)methan („Formylaalen“) - ein Orthoameisensäureamid-Derivat mit sechs Formylgruppen / Orthoam ides, LV [1]. C7H7N3O6 - Tris(diformylamino)methane ( “Formylaalen”) - an Orthoformic Acid Amide Derivative with Six Formyl Groups

The preparation of tris(diformylamino)methane (3), a hitherto unknown derivative of orthoformic acid, is described. In the presence of a Lewis acid the orthoamide 3 formylates activated aromatic compounds.

Abstract 4746: Modulation of suppressive myeloid populations by tasquinimod

Purpose: Suppressive myeloid cells such as myeloid derived suppressor cells (MDSCs) and tumor associated macrophages (TAMs) are a major barrier of cancer immunotherapy. These populations suppress immune responses, promote angiogenesis, and facilitate cancer progression and metastasis. Tasquinimod is an experimental anti-angiogenic agent tested in prostate cancer. In the current study, we investigated the novel immunomodulatory effects of tasquinimod. We focused on the modulation of myeloid populations by tasquinimod since tasquinimod binds to the inflammatory protein S100A9, which potentially activates MDSCs. Thus, we studied whether tasquinimod affects the induction/function of MDSCs and TAMs, and whether this agent can facilitate vaccine therapy in prostate and kidney cancer models.

Experimental Design: The effects of tasquinimod on myeloid cells were tested in Myc-CaP and TRAMP transplantable prostate cancer models, and the RENCA orthotopic model of renal cell carcinoma. Splenocytes, blood cells, and cells from tumor samples were isolated from tumor bearing mice. The samples were subjected to staining with MDSC markers (Gr1 and CD11b) and macrophage markers (F4/80 and CD206), and to flow cytometry analysis. An immunotherapy combining tasquinimod with a modified survivin peptide vaccine, SurVaxM, was administered in Myc-CaP and TRAMP models. Tumor growth, MDSCs, and TAMs accumulation and their function after different treatments were monitored. Tasquinimod's effect on metastases is currently being tested in a LuCaP 23.1 orthotopic prostate cancer model.

Results: Tasquinimod treatment reduced peripheral Gr1−CD11b+ monocytes, but did not affect the number of peripheral Gr1+CD11b+ MDSCs. However, tumor infiltrating Gr1+CD11b+ MDSCs significantly decreased following tasquinimod treatment (60% reduction, p = 0.03). In addition, Gr1−CD11b+ monocytes gained the macrophage marker, F4/80, in tumors, and tasquinimod reduced the M2 macrophages (immunosuppressive macrophages) in both peripheral sites and tumors (56% reduction, p = 0.04). Tasquinimod had a modest effect on the suppressive function of MDSCs. In the vaccine therapy, tasquinimod, combined with SurVaxM, improved antitumor immune responses and reduced tumor growth (48% inhibition, p = 0.03), as compared to vehicle and single treatments (no inhibition by SurVaxM, 15% inhibition by tasquinimod).

Conclusions: Our study suggests that tasquinimod does not affect the expansion of Gr1+CD11b+ MDSCs induced by tumor, but interferes with the migration of MDSCs to tumor sites. Moreover, tasquinimod targets M2 macrophages, possibly by depleting the monocytic precursor populations such as Gr1−CD11b+ monocytes. By inhibiting MDSCs and TAMs, tasquinimod has an immunomodulatory potential to target cancer progression and metastasis, and to improve immunotherapies.

Citation Format: Li Shen, Michael Ciesielski, Kiersten M. Miles, Robert Fenstermaker, Roberto Pili. Modulation of suppressive myeloid populations by tasquinimod. [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 4746. doi:10.1158/1538-7445.AM2013-4746

Abstract B91: Tasquinimod targets immuno-suppressive myeloid cell populations and enhances immunotherapy in murine prostate cancer models

Purpose: A major component of the immunosuppressive environment responsible for immune tolerance in cancer is represented by myeloid cell populations such as myeloid derived suppressor cells (MDSCs) and tumor associated macrophages (TAMs). These cells facilitate carcinogenesis and tumor progression by impairing T and NK cells activation and contributing to modulate angiogenesis. Tasquinimod is an anti-angiogenic and immunomodulatory agent that has shown clinical benefit in patients with prostate cancer. This agent has been found to bind to the inflammatory protein S100A9, to block the interaction of S100A9 with myeloid cells surface receptors, and therefore has the potential to affect accumulation and function of these cells.

Experiments and Objectives: We tested tasquinimod in combination with a vaccine therapy in two castration resistant, syngenic transplantable murine prostate cancer models: CR Myc-Cap and TRAMP-C2. This study had the following objectives: 1) to explore tasquinimod's novel immunomodulatory activities and underlining mechanism; 2)To investigate whether tasquinimod inhibits the induction and function of immunosuppressive myeloid cell populations; 3) To assess whether tasquinimod can facilitate vaccine therapy in the castrate resistant prostate cancer models.

Results: We observed that the peripheral MDSCs (in blood and spleen) dramatically increased in tumor bearing mice as compared to naïve mice. The MDSCs number increase correlated with disease progression in the transgenic model. Tasquinimod treatment depleted Gr1-CD11b+, Ly6G-CD11b+ (monocytic MDSCs) myeloid cells and M2 macrophages in peripheral sites, and reduced Gr1+CD11b+ MDSCs infiltrates in the tumors. In addition, tasquinimod (10mg/kg) dramatically improved tumor-specific immune responses, including the granzyme B expression in CD8 cells and cytotoxicity of splenocytes, and enhanced anti-tumor activity of a survivin-mimetic peptide vaccine.

Conclusions: 1. MDSCs accumulate in prostate cancer models suggesting that MDSCs may contribute to immune tolerance in prostate cancer. 2. Tasquinimod reduces immunosuppressive MDSCs and M2 macrophage and may facilitate vaccine therapy by enhancing cell-mediated cytotoxic tumor cell killing and the anti-tumor immune response.

Citation Format: Li Shen, Kiersten Marie Miles, Michael Ciesielski, Leigh Ellis, Robert Fenstermaker, Roberto Pili. Tasquinimod targets immuno-suppressive myeloid cell populations and enhances immunotherapy in murine prostate cancer models. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B91.

Class I histone deacetylase inhibitor entinostat suppresses regulatory T cells and enhances immunotherapies in renal and prostate cancer models

Background

Immunosuppressive factors such as regulatory T cells (Tregs) limit the efficacy of immunotherapies. Histone deacetylase (HDAC) inhibitors have been reported to have antitumor activity in different malignancies and immunomodulatory effects. Herein, we report the Tregs-targeting and immune-promoting effect of a class I specific HDAC inhibitor, entinostat, in combination with either IL-2 in a murine renal cell carcinoma (RENCA) model or a survivin-based vaccine therapy (SurVaxM) in a castration resistant prostate cancer (CR Myc-CaP) model.

Methods and Results

RENCA or CR Myc-CaP tumors were implanted orthotopically or subcutaneously, respectively. Inoculated mice were randomized into four treatment groups: vehicle, entinostat, cytokine or vaccine, and combination. Tregs in the blood were assessed by FACS analysis. Real time quantitative PCR and Western blot analysis of isolated T cell subpopulations from spleen were performed to determine Foxp3 gene and protein expression. The suppressive function of Tregs was tested by T cell proliferation assay. Low dose (5 mg/kg) entinostat reduced Foxp3 levels in Tregs and this was associated with enhanced tumor growth inhibition in combination with either IL-2 or a SurVaxM vaccine. Entinostat down-regulated Foxp3 expression transcriptionally and blocked Tregs suppressive function without affecting T effector cells (Teffs). In vitro low dose entinostat (0.5 µM) induced STAT3 acetylation and a specific inhibitor of STAT3 partially rescued entinostat-induced down-regulation of Foxp3, suggesting that STAT3 signaling is involved in Foxp3 down-regulation by entinostat.

Conclusions

These results demonstrate a novel immunomodulatory effect of class I HDAC inhibition and provide a rationale for the clinical testing of entinostat to enhance cancer immunotherapy.

Abstract 1792: Selective class I HDAC inhibitor SNDX-275 enhances anti-tumor survivin vaccine therapy by suppressing regulatory T cells in a model of prostate cancer

Immunotherapy has been recently approved for the treatment of castrate refractory prostate cancer but its clinical benefit is limited. A major barrier in vaccine therapy remains the presence of immunosuppressive factors such as regulatory T cells (Tregs). Tregs are predominant in various cancers including advanced prostate cancer. Studies have shown that tolerance mechanisms can be induced by tumor and surrounding stromal cells or immunotherapy itself. In our laboratory we have observed that SNDX-275, a class I HDAC specific inhibitor can down-regulate Foxp3 expression, suppress Treg function, and enhance the anti-tumor effect of cytokine therapy. Here, we present a current study carried out in a castration-resistant prostate cancer model where we combined SNDX-275 with a novel peptide mimic vaccine (SVN53-67/M57-KLH (SurVaxM)) targeted towards the intracellular tumor associated antigen (TAA) survivin. We hypothesize that combination of SNDX-275 and SurVaxM vaccine will mediate a greater anti-tumor response by inducing an efficient CD8+ cytotoxic T cell response and overcoming Tregs mediated immunosuppressive effect in tumor bearing animals. We have generated and utilized a transplant castrate resistant (CR) PCa murine model. Myc-CaP cell lines derived from the Hi-Myc transgenic prostate cancer mouse model were injected (1×106 cells/mouse) subcutaneously to male FVB Wt mice. Survivin expression has been confirmed in myc tumors. Tumor bearing animals were surgically castrated post tumor establishment and consequent tumors were passaged through 5 additional rounds of surgically castrated Wt FVB male mice. CR tumor bearing mice were randomized into four groups and treated with vehicle, SNDX-275 (5 days/week, 5mg/kg), SurVaxM (1 dose/week) or combination. We demonstrate that treatment with SNDX-275 alone and in combination efficiently reduced Foxp3 expression in Tregs. Following four weeks of treatment, SNDX-275 or SurVaxM single treatment displayed modest anti-tumor effect (10-25% of reduction). Excitingly, combination of SNDX-275 and SurVaxM dramatically reduced tumor weight (∼80% reduction, p=0.002) and inhibited tumor growth rate when compared to either vehicle or single treatment groups. Tumor specific CD8+ T cell response and tumor specific cytotoxicity are being evaluated. This is the first study, to our knowledge, to show that the class I HDAC inhibitor SNDX-275 in combination with a vaccine therapy enhances prostate tumor response by inhibition of immunosuppressive Tregs. These findings suggest that the combination of a class I HDAC inhibitor with vaccine therapy is a rational therapeutic strategy for advanced, castrate refractory prostate cancer.

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 1792. doi:10.1158/1538-7445.AM2011-1792

Immunization with a mimotope of GD2 ganglioside induces CD8+ T cells that recognize cell adhesion molecules on tumor cells

The GD2 ganglioside expressed on neuroectodermal tumor cells has been used as a target for passive and active immunotherapy in patients with malignant melanoma and neuroblastoma. We have reported that immunization of mice with a 47-LDA mimotope of GD2, isolated from a phage display peptide library with anti-GD2 mAb 14G2a, induces MHC class I-restricted CD8(+) T cell responses to syngeneic neuroblastoma tumor cells. The cytotoxic activity of the vaccine-induced CTLs was independent of GD2 expression, suggesting recognition of a novel tumor-associated Ag cross-reacting with 47-LDA. Glycan microarray and immunoblotting studies using 14G2a mAb demonstrated that this Ab is highly specific for the entire carbohydrate motif of GD2 but also cross-reacts with a 105 kDa glycoprotein expressed by GD2(+) and GD2(-) neuroblastoma and melanoma cells. Functional studies of tumor cells grown in three-dimensional collagen cultures with 14G2a mAb showed decreases in matrix metalloproteinase-2 activation, a process regulated by the 105 kDa-activated leukocyte cell adhesion molecule (ALCAM/CD166). A recombinant CD166 glycoprotein was shown to be recognized by 14G2a Ab and inhibition of CD166 expression by RNA interference ablated the cell sensitivity to lysis by 47-LDA-induced CD8(+) T cells in vitro and in vivo. The binding of 14G2a to CD166 was not disruptable by a variety of exo- and endo-glycosidases, implying recognition of a non-glycan epitope on CD166. These results suggest that the vaccine-induced CTLs recognize a 47-LDA cross-reactive epitope expressed by CD166, and reveal a novel mechanism of induction of potent tumor-specific cellular responses by mimotopes of tumor-associated carbohydrate Ags.

Induction of protective immune responses against NXS2 neuroblastoma challenge in mice by immunotherapy with GD2 mimotope vaccine and IL-15 and IL-21 gene delivery

The GD2 ganglioside expressed on neuroectodermal tumor cells is weakly immunogenic in tumor-bearing patients and induces predominantly IgM antibody responses in the immunized host. Using a syngeneic mouse challenge model with GD2-expressing NXS2 neuroblastoma, we investigated novel strategies for augmenting the effector function of GD2-specific antibody responses induced by a mimotope vaccine. We demonstrated that immunization of A/J mice with DNA vaccine expressing the 47-LDA mimotope of GD2 in combination with IL-15 and IL-21 genes enhanced the induction of GD2 cross-reactive IgG2 antibody responses that exhibited cytolytic activity against NXS2 cells. The combined immunization regimen delivered 1 day after tumor challenge inhibited subcutaneous (s.c.) growth of NXS2 neuroblastoma in A/J mice. The vaccine efficacy was reduced after depletion of NK cells as well as CD4(+) and CD8(+) T lymphocytes suggesting involvement of innate and adaptive immune responses in mediating the antitumor activity in vivo. CD8(+) T cells isolated from the immunized and cured mice were cytotoxic against syngeneic neuroblastoma cells but not against allogeneic EL4 lymphoma, and exhibited antitumor activity after adoptive transfer in NXS2-challenged mice. We also demonstrated that coimmunization of NXS2-challenged mice with the IL-15 and IL-21 gene combination resulted in enhanced CD8(+) T cell function that was partially independent of CD4(+) T cell help in inhibiting tumor growth. This study is the first demonstration that the mimotope vaccine of a weakly immunogenic carbohydrate antigen in combination with plasmid-derived IL-15 and IL-21 cytokines induces both innate and adaptive arms of the immune system leading to the generation of effective protection against neuroblastoma challenge.

Complexes of Schiff bases and intermediates in the copper-catalyzed oxidative heterocyclization by atmospheric oxygen

After complexation with copper(II) ions, Schiff bases 1a-d may undergo an oxidative ring closure using atmospheric oxygen to give a number of imidazo[1,5-a]pyridines 2, an imidazo[1,5-a]imidazole 3, and an imidazo[5,1-a]isochinoline 4. This ligand oxidation can be performed with catalytic amounts of copper ions in the reaction. A catalytic cycle for the copper-catalyzed oxidative heterocyclization will be presented together with isolated copper complexes of Schiff bases 1a,b and intermediates 5 and 8 that were found by X-ray structure analyses which confirm this reaction scheme.

Assessment of intercomponent interaction in phenylene bridged dinuclear ruthenium(ii) and osmium(ii) polypyridyl complexes

The synthesis and characterisation of [Ru(bipy)(2)(L1)](2+) and the homodinuclear complexes [M(bipy)(2)(L1)M(bipy)(2)](4+)(where M = Ru or Os), employing the ditopic ligand, 1,4-phenylene-bis(1-pyridin-2-ylimidazo[1,5-a]pyridine)(L1), are reported. The complexes are identified by elemental analysis, UV/Vis, emission, resonance Raman, transient resonance Raman and (1)H NMR spectroscopy, mass spectrometry and electrochemistry. The X-ray structure of the complex [Ru(bipy)(2)(L1)(bipy)(2)Ru](PF(6))(4) is also reported. DFT calculations, carried out to model the electronic properties of the compounds, are in good agreement with experiment. Minimal communication between the metal centres is observed. The low level of ground state electronic interaction is rationalized in terms of the poor ability of the phenyl spacer in facilitating superexchange interactions. Using the electronic and electrochemical data a detailed picture of the electronic properties of the RuRu compound is presented.

A prospective, randomized, unicenter study comparing laparoscopic and open treatments of acute appendicitis

BACKGROUND

Appendectomy in the course of acute appendicitis is one of the most frequently performed surgical procedure in general surgery. The aim of this study was to compare the results of laparoscopic and conventional treatments for acute appendicitis in a prospective, randomized, unicenter study.

METHODS

The study involved 200 patients treated for acute appendicitis in the Department of General and Vascular Surgery at Ceynowa Hospital in Wejherowo, Poland.

RESULTS

The mean operative time for open surgery was 36.99 min. For laparoscopic method the operation was longer, requiring 47.75 min. Suction drainage was applied in 23 patients treated conventionally and 50 patients treated laparoscopically ( p < 0.05). The requirement for analgesia, measured by the number of metamizole ampules, was significantly higher in the conventional group. Pain on postoperative days 2 and 7 measured using a visual analog scale, was significantly more severe for the patients treated conventionally. The hospital stay in both groups did not differ significantly: 5.03 days for the conventional group and 4.71 days for the laparoscopic group. The time until return to work and social activities in the laparoscopic group (15.85 days) and was significantly shorter than in the conventional group (19.65 days). Seven complications occurred in the conventional group (6.7%) and nine (9.4%) in the laparoscopic group. The difference was not statistically significant. No deaths occurred.

CONCLUSIONS

On the basis of the conducted study, it may be assumed that laparoscopic appendectomy is a safe procedure, and that postoperative morbidity is comparable with that for a conventional operation. There was less postoperative pain and shorter recovery time after laparoscopic surgery than after the open procedure.