Cancer immunoediting hypothesis: history, clinical implications and controversies.

The main function of the immune system is to protect against infectious pathogens and to ensure tissue homeostasis. The latter function includes preventing autoimmune reactions, tolerizing cells to nonpathogenic environmental microorganisms, and eliminating apoptotic/damaged, transformed, or neoplastic cells. The process of carcinogenesis and tumor development and the role of the immune system in inhibiting progression of cancer have been the subject of intense research since the end of the 20th century and resulted in formulation of the cancer immunoediting hypothesis. The hypothesis postulates three steps in oncogenesis: 1) elimination - corresponding to immunosurveillance, 2) equilibrium in which the growth of transformed or neoplastic cells is efficiently controlled by immune effector mechanisms, and 3) escape in which cancer progresses due to an ineffective antitumor response. In parallel, a new field of science - immune-oncology - has arisen. Attempts are also being made to quantify intra-tumoral and peritumoral T cell infiltrations and to define optimal immunological parameters for prognostic/predictive purposes in several types of cancer. The knowledge of relationships between the tumor and the immune system has been and is practically exploited therapeutically in the clinic to treat cancer. Immunotherapy is a standard or supplementary treatment in various types of cancer.

Therapeutic metastatic prostate cancer vaccines: lessons learnt from urologic oncology.

INTRODUCTION: Therapeutic cancer vaccines have been recognized as a promising treatment option in clinical oncology for nearly three decades. However, despite many efforts, only one cancer vaccine - sipuleucel-T, activating the anti-PAP (prostatic acid phosphatase) immune response, has obtained Food and Drug Administration (FDA) approval. MATERIAL AND METHODS: This review describes the most advanced research on the use of therapeutic cancer vaccines in the treatment of prostate cancer. RESULTS: In addition to sipuleucel-T, which was approved in urologic oncology in 2010, four cancer vaccines were and have been tested in phase III clinical trials in patients with metastatic castration resistant prostate cancer (mCRPC): GVAX (prostate cancer variant) containing irradiated prostate cancer cell, PPV peptide vaccine, PCVAC/PCa dendritic cell-based vaccine and PROSTVAC anti PSA (prostate-specific antigen) vaccine. This review compares the most promising and best-studied cancer vaccines: sipuleucel-T and PROSTVAC. Currently, both vaccines have been tested in combination with other therapeutic approaches, including check point inhibitors. CONCLUSIONS: It seems possible that the efficacy of sipuleucel-T and PROSTVAC could be increased in combination therapy with other medications.

Comparative Study of Immunomodulatory Agents to Induce Human T Regulatory (Treg) Cells: Preferential Treg-Stimulatory Effect of Prednisolone and Rapamycin.

T regulatory (Treg) cells play a critical role in the maintenance of self-tolerance, as well as in inhibition of inflammation and exaggerated immune response against exogenous antigens. They develop in the thymus (tTreg cells) but also may be generated at the peripheral tissues, including tumor microenvironment (pTreg cells), or induced in vitro in the presence of transforming growth factor (TGF)-ß (iTreg cells). Since tTreg cells constitute a minor fraction of peripheral blood lymphocytes in physiological conditions, an alternative way to obtain high number of functional Treg cells for therapeutic purposes is their generation in vitro from conventional T cells. In our studies, we compared effectiveness of several pharmacological agents with suggested immunomodulatory effects on Treg development (rapamycin, prednisolone, inosine pranobex, glatiramer acetate, sodium butyrate, and atorvastatin) to optimize Treg-inducing protocols. All but one (atorvastatin) immunomodulators augmented induction of polyclonal Treg cells in cultures. They were effective both in increasing the number of CD4+CD25highFoxp3high cells and Foxp3 expression. Rapamycin and prednisolone were found the most effective. Both drugs prolonged also phenotypic stability of Treg cells and induced fully active Treg cells in a functional assay. In the assay, prednisolone appeared superior versus rapamycin. The results, on the one hand, may be helpful in planning optimal protocols for generation of Treg cells for clinical application and, on the other hand, shed some light on mechanisms of the immunomodulatory activity of some tested agents observed in vivo.

Synergistic antitumor effects of histone deacetylase inhibitor scriptaid and bortezomib against ovarian cancer cells.

Despite debulking surgery and good initial response to chemotherapy, the majority of patients with advanced ovarian cancer relapse and succumb to their disease. Thus, there is a pressing need to improve treatment outcome. In the present study, the antitumor activity of histone deacetylase (HDAC) inhibitor scriptaid in combination with bortezomib or conventional chemotherapeutics was tested in vitro against representative ovarian cancer cell lines: SKOV­3, MDAH 2774, and OVP­10. Incubation of ovarian cancer cells with scriptaid and bortezomib (or doxorubicin) led to synergistic antitumor effects. As shown in the Annexin V-FITC/PI assay and western blot analysis of caspase­3/-9 and p21 protein expression, these synergistic antitumor effects were due to both induction of apoptosis and inhibition of proliferation. Since synergistic antitumor activity of scriptaid and bortezomib appeared in suboptimal concentrations, one can assume that the administration of the combination of these agents to ovarian cancer patients can exert the therapeutic effect in parallel with limited general toxicity of the treatment.

Potentialization of N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) cytotoxic activity by 2-(1-adamantylamino)-6-methylpyridine (AdAMP) in human ovarian cancer cells.

OBJECTIVES: TNF is one of the key cytokines involved in cancer development. TNF signaling can result in both stimulating and inhibitory signals that can result in opposite biological effects in cancerogenesis. 2-(1-adamantylamino)-6-methylpyridine (AdAMP) enhances TNF secretion whereas N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) is a NF-κB inhibitor potentially stimulating proapoptotic TNF signals. The aim of the study was to assess the effect of TPCK in combination with AdAMP on human ovarian cells. MATERIAL AND METHODS: CAOV-1 human ovarian cell line was incubated with TPCK and AdAMP for 24 hours. The cytotoxic effect was evaluated in a crystal violet assay. A monoclonal antibody against TNF, Infliximab, was added to examine the possible mechanism of interactions. RESULTS: Depending on concentration, AdAMP potentialized cytotoxic activity of TPCK or had a synergistic effect with TPCK. Infliximab did not reverse cytotoxicity of AdAMP and TPCK and in some cytotoxic and non-cytotoxic concentrations even enhanced their cytotoxicity. CONCLUSIONS: AdAMP and TPCK cytotoxicity seems to be dependent on TNF signaling, however, the exact mechanism of interactions remains unclear.

IN VITRO INfIBITION OF HHV-1 REPLICATION BY INOSINE PRANOBEX AND INTERFERON-α.

Key issues in the development of novel antivirals are the emergence of resistant strains. The development of new drugs effective against herpes diseases has proven to be both difficult and time-consuming. Some alternative may be to optimize the efficacy and selectivity of existing antiviral drugs or combining them with other well known agents. Inosine pranobex exerts a direct antiviral effect as well as secondary effect to its immunomodulatory activity. We found that increasing concentrations of inosine pranobex (50-400 µg/mL) produced progressively growing inhibitory effect on HHV-1 replication, following infection of different cell lines. The combination of 1000 IU/mL IFN-α and inosine pranobex also resulted in enhanced anti-HHV activity. Immunotherapy may be beneficial for patients from whom strains resistant to currently known antiviral drugs have been isolated.

Interferon-α and inosine pranobex-mediated inhibition of reploication of human RNA viruses in vitro.

INTRODUCTION: Interferon- a (IFN-a), produced by immune cells, exhibits pleiotropic anti- viral activity. Inosine pranobex (PI), a synthetic derivative of a purine, shows direct anti- viral activity, and also acts indirectly, by activation of immune cells. The aim of this study was to evaluate an in vitro inhibition of Coxackievirus A16 (CAI6), enterovirus 71 (EV71) and human parainfluenza virus 4 (HPIV-4) replication by PI in combination with IFN-a. MATERIALS AND METHODS: In the present study we evaluated an in vitro effect of interferon-a and inosine pranobex on replication ofRNAviruses: CA-16, EV71, HPIV-4. Antiviral effects of IFN-a and IPwere assessed by phenotypic assays. The yield reduction assay (YRA), which evaluates the ability of the compounds to inhibit virus multiplication in cell cultures, was ap- plied. The Reed-Muench statistical method was used to determine the 50% end point (IC51). RESULTS: Our studies have shown that combination of IFN-a and inosine pranobex dis- play higher efficacy than treatment with either compound alone, and suggest syn- ergy that may increase therapeutic effectiveness. The reduction of the average viral ti- ters of EV71, CA-16 and HPIV-4 in A549 cell culture after applying 400 Ig/mL Ip and IFN-a (1000 IU/mL), in comparison to the viral titer in the control was reduced by 1,76 log,, TCID,,/ml, o 3,00 log, TCID50/ml , and 1,60 log,( TCID50/ml respec- tively. The antiviral activity of the tested compounds was also analyzed on the basis of IC., values. Application of 1000 IU/ml IFN-a, with PI after infection of A549 cells with mention above viruses reduced the IC,, by 3,5%, 41,3% and 29% respectively. CONCLUSIONS: Our study demonstrated that enhanced antiviral activity was observed when cells infected with RNA viruses were treated with combination of IFN-a and IP. The ef- fectiveness of IFN-a and IP under these conditions has not been previously reported. CA16 virus turned out to be the most sensitive to the action of used inhibitors.

[Inosine pranobex - cytotoxic activities and effect of on replication of human parainfluenza viruses (HPIV-2, HPIV-4), entroviruses (CA16, EV71) and adenoviruses (HAdV-2, HAdV-5) in vitro]. / Pranobeks inozyny - dzialanie cytotoksyczne oraz wplyw na replikacje ludzkich wirusów paragrypy (HPIV-2, HPIV-4), enterowirusów (CA16, EV71) i adenowirusów (HAdV-2, HAdV-5) w badaniu in vitro.

INTRODUCTION: There are no specific antivirals designed for many viral infections. Inosine pranobex (PI) is a purine nucleoside that is involved in a wide variety of intracellular biochemical processes. The mechanism of action in human body is still unclear but numerous studies have demonstrated that this drug inhibits viral replication and exhibit pleiotropic effect. We evaluated in vitro effect of inosine pranobex (PI) on replication of human viruses: parainfluenza viruses (HPIV-2, HPIV-4), entroviruses A (CA16, EV71) and adenoviruses C (HAdV-2, HAdV-5). MATERIALS AND METHODS: In the present study, cytotoxic effect of inosine pranobex was assessed using A549 cell line exposed to different concentrations of compound (PI: 50-800 ig/mL) for 48 hours. Cytotoxic effect of inosine pranobex was assessed visually using light, inverted microscopy Olympus CK2 under 400x magnification and by the MTT colorimetric assay. Antiviral effect was estimated according to the reduction of virus titer. The yield reduction assay (YRA), which evaluates the ability of the PI (50-800 µg/mL) to inhibit virus multiplication in cell cultures, was applied. The cytopathic effect of the virus was evaluated 48 h after infection ofA549 cell cultures with viruses by means of light, inverted microscopy. The Reed-Muench statistical method was used to determine the 50% end point (IC50) (yield reduction assay, YRA) in the presence of inosine pranobex with the controlled one. RESULTS: There were no morphological changes, as assessed visually, in cell cultures treated with PI. MTT cytotoxicity assay confirmed microscopic observations. The viability of cells in the presence of the tested compounds was average 98, 36 %. After conducting the experiments and analyzing the results we noticed that higher concentrations of PI strongly inhibited multiplication of all viruses. PI weakly reduced the titer of infectious enteroviruses and HPIV-4 as compared with the control. Adenoviruses showed the highest sensitivity to the antiviral activity of PI, however, increasing concentrations of PI up to 800 µg /ml slightly enhanced the antiviral activity of 400 µg/ml PI. CONCLUSIONS: Our study demonstrated that inosine pranobex shows no cytotoxic activity on the A549 cell line. In conducted study was observed that adenoviruses (HAdV-2 and HAdV-5) and HPIV-2 have the highest sensitivity to the antiviral activity of inosine pranobex from all tested viral strains.

Immunomodulatory effects of inosine pranobex on cytokine production by human lymphocytes.

Inosine pranobex (inosine dimepranol acedoben, isoprinosine) (Inos) is an immunomodulatory and antiviral drug used in some viral infections, especially in patients with weakened immunity. In the present study, effects of Inos on the production of cytokines attributable to Th1 (IL-2, IFN-g, and TNF-a) or Th2 cells (IL-4, IL-5, and IL-10) were tested in human peripheral blood lymphocyte cultures stimulated with phytohemagglutinin (PHA). Inos enhanced TNF-a secretion significantly (in short-term--24-hour, and prolonged term--72-hour cultures) and IFN-g (in 72-hour cultures). Surprisingly, production of IL-10 by PHA-stimulated lymphocytes was suppressed by Inos in a dose-dependent manner in both 24-hour and 72-hour cultures. These results shed some light on immunomodulatory properties of Inos and suggest applicability of this agent in patients with a depressed function of the immune system.

Inhibition of adenovirus multiplication by inosine pranobex and interferon α in vitro.

There are no specific antivirals designed for adenoviral infections. Due to many cases of adenovirus infections worldwide, epidemic nature of some types of adenoviruses, and growing number of patients with severe adenoviral infections resulting from dysfunction the immune system, the need for searching an effective and safe therapy is increasing. Inosine pranobex exerts antiviral effects which are both direct and secondary to immunomodulatory activity. In the present study we evaluated in vitro effect of inosine pranobex and interferon α (IFN-α) on replication of HAdV-2 and HAdV-5. The effectiveness of inosine pranobex under these conditions has not been previously reported. In conducted study we reported that inosine pranobex reduced the titer of infectious HAdV-2 and HAdV-5 in vitro. Higher concentrations of IP strongly inhibited multiplication of viruses. Combination of inosine pranobex and IFN-α display higher efficacy than either treatment alone and suggest that both agents may increase therapeutic effectiveness without augmenting toxic effects. Combination index calculations showed that inosine pranobex and INF-α synergistically inhibit HAdV-2 and HAdV-5 titers in A549 cells.

Interleukin 12: still a promising candidate for tumor immunotherapy?

Interleukin 12 (IL-12) seemed to represent the ideal candidate for tumor immunotherapy, due to its ability to activate both innate (NK cells) and adaptive (cytotoxic T lymphocytes) immunities. However, despite encouraging results in animal models, very modest antitumor effects of IL-12 in early clinical trials, often accompanied by unacceptable levels of adverse events, markedly dampened hopes of the successful use of this cytokine in cancer patients. Recently, several clinical studies have been initiated in which IL-12 is applied as an adjuvant in cancer vaccines, in gene therapy including locoregional injections of IL-12 plasmid and in the form of tumor-targeting immunocytokines (IL-12 fused to monoclonal antibodies). The near future will show whether this renewed interest in the use of IL-12 in oncology will result in meaningful therapeutic effects in a select group of cancer patients.

Synergistic antitumor effect of JAWSII dendritic cells and interleukin 12 in a melanoma mouse model.

One of the possible ways to augment dendritic cell (DC) efficacy in presentation of tumor antigens to effector T cells is pulsing them with tumor-cell lysates and incubation with certain immunostimulators. We present the results of an immunotherapeutic approach in a murine B78-H1 model using as a vaccine JAWSII DCs in combination with IL-12. Prior to the in vivo experiments, phenotypic characterization of JAWSII cells was performed and optimal conditions for stimulation of these cells were established. As no production of IL-12 by JAWSII cells was found, injections of this cytokine were introduced to vaccination protocols. Three vaccination schedules have been tested: i) prophylactic, ii) therapeutic-intratumoral, and iii) therapeutic-systemic. In all the protocols, vaccination with pulsed + stimulated JAWSII cells in combination with IL-12 was superior to the treatment with either agent alone and led to eradication of the tumor in several cases. The results of the study may be helpful in planning optimal DC-based therapeutic protocols in cancer patients.

Synergistic cytotoxic effect of sulindac and pyrrolidine dithiocarbamate against ovarian cancer cells.

Sulindac, a non-steroidal anti-inflammatory drug, suppresses carcinogenesis and inhibits growth of tumor cells. Pyrrolidine dithiocarbamate (PDTC), a potent NF-κB inhibitor, has been also identified as a potential anti-neoplastic agent. We hypothesized that combination of sulindac and PDTC could result in augmentation of cytotoxicity against ovarian cancer cells. The effect of sulindac and PDTC was examined on several ovarian cancer lines. Tumor cell viability was assessed using the MTT assay. Annexin-V/PI staining was used to detect apoptosis, cell cycle distribution was analyzed in FACS, and expression of cellular proteins was detected by western blotting. Incubation of OVA-14, OVP-10 and CAOV-1 ovarian cancer cells with sulindac and PDTC resulted in significantly greater inhibition of cell viability compared to either compound alone. In a model of OVA-14 cells it was evident that this effect was not related to the expression of COX enzymes since both active (sulindac sulfide) and inactive (sulindac) in vitro compounds affected the growth of tumor cells to a similar extent and synergized in cytotoxicity with PDTC. Combination of sulindac and PDTC lead to G0 arrest and massive apoptosis in co-treated cultures. Western blotting analysis argued for induction of the mitochondrial apoptotic pathway. These data demonstrate the synergistic cytotoxic effect of sulindac and PDTC on ovarian cancer cells through apoptosis and cell cycle arrest and prompt to test the efficacy of this combination in animal models.

[Antitumor effects of sulindac in ovarian cell cultures]. / Przeciwnowotworowy efekt sulindaku w hodowlach komórek raka jajnika.

OBJECTIVE: The purpose of our study was to assess susceptibility of cells of various ovarian cell lines on different nonsteroidal anti-inflammatory drugs (NSAIDs). MATERIALS AND METHODS: Cytotoxic effect of NSAIDs was tested using MTT colorimetric assay. RESULTS: Amongst 6 NSAIDs tested: sulindac, sulindac sulfide, sulindac sulfone, acetylsalicylic acid, nimesulide, and rofecoxib, viability of ovarian carcinoma cells was compromised most strongly by sulindac and sulindac sulfide and concerned all the cell lines tested: SKOV-3, MDAH 2774, OVCA-1, and OVP-10. Sulindac sulfone and rofecoxib also displayed some cytotoxic effect during prolonged 72-hour incubation. Other NSAIDs tested: nimesulide and acetylsalicylic acid were devoid of cytotoxic effect on ovarian cancer cells. CONCLUSION: Our results are encourage enough to conduct clinical trials that could allow to draw conclusions regarding potential application of sulindac in the adjuvant treatment of a standard chemotherapy of ovarian cancer.

Interleukin 15 as a promising candidate for tumor immunotherapy.

Interleukin 15 participates in the development of important immune antitumor mechanisms. It activates CD8(+) T cells, natural killer (NK) cells, NK T cells, and can promote the formation of antitumor antibodies. IL-15 can also protect T effector cells from the action of T regulatory cells and reverse tolerance to tumor-associated antigens. In pre-clinical studies IL-15 has been found to demonstrate potentiated antitumor effects following pre-association with IL-15Rα, or when used in combination with chemotherapy, adoptive therapy, monoclonal antibodies, and tumor vaccines. Although a clinical trial based on application of IL-15 in tumor patients has already begun, it is important to be aware of its potential side effects, including induction of autoimmunity and promotion of proliferation, survival, and dissemination of some tumor cells.

Optimization of activation requirements of immature mouse dendritic JAWSII cells for in vivo application.

Dendritic cells (DCs) are specialized antigen-presenting cells that are present in peripheral tissues in a resting (immature) state. Their activation is a critical step in the initiation of the primary immune response. In the present study, we optimized in vitro conditions for maturation of commercially available immortalized mouse dendritic precursor JAWSII cells. These cells express surface markers and have properties that are typical of immature DCs and macrophages (e.g. MHC class I and II markers, CD80 molecules, high endocytic capacity), as well as TLR1, TLR3, TLR4, TLR6, and TLR7 receptors. When stimulated with poly I:C (and also LPS) JAWSII cells produced large amounts of IL-6, TNF-α and MCP-1. Incubation of JAWSII cells with IFN-γ markedly increased expression of MHC class I molecules and, more importantly, combination of this cytokine with poly I:C significantly increased expression of CD40 surface protein and CD11c, the most characteristic marker of mouse DCs. The combination of both agents also inhibited the endocytic abilities of JAWSII cells. In in vivo migration studies, exposure of JAWSII cells to poly I:C and IFN-γ led to increased accumulation of these cells in regional lymph nodes. Functional in vivo studies showed that tumor cell lysate-pulsed and subsequently poly I:C/IFN-γ-stimulated JAWSII cells promoted development of specific T cells in lymph nodes. Our studies show that the combination of optimal endogenous and exogenous ligands may induce phenotypic and functional maturation of JAWSII cells necessary for the accomplishment of their antigen-presenting function in vivo.

Interleukin 15 augments antitumor activity of cytokine gene-modified melanoma cell vaccines in a murine model.

Many studies have demonstrated that interleukin 15 (IL-15) is a cytokine with strong antitumor properties and have suggested its potential use in tumor immunotherapy. IL-15 exerts its effect on innate and acquired immunity with the most prominent action in NK cells and CD8(+) memory T cells. Therefore, many authors have proposed that IL-15 could be a good candidate for augmenting the efficacy of vaccination strategies. In our experiments, in a model of B78-H1 murine transplantable melanoma, tumor-bearing mice were treated with different cytokine-gene modified tumor cell vaccines (producing TNF-alpha, GM-CSF, IL-12 or IL-6/sIL-6R) followed by a series of IL-15 injections. In order to investigate the infiltration of treated tumors by leukocytes, immunohistochemical staining was performed. In every case, the combined therapy was superior to the treatment with either a vaccine or IL-15 alone. Tumors treated with the combination of B78-H1 melanoma cells secreting IL-12 (B78/IL-12 vaccine) and IL-15 were heavily infiltrated by granulocytes. IL-15, either alone or in combination with the B78/IL-12 vaccine, influenced infiltration of tumors with CD3(+) lymphocytes, CD4(+)and CD8(+). To our knowledge, this is the first report that shows the universal genetically-modified tumor cell vaccine-augmenting properties of IL-15. The cytokine can be useful as an adjuvant in cancer gene therapy in humans.

Statins impair antitumor effects of rituximab by inducing conformational changes of CD20.

BACKGROUND: Rituximab is used in the treatment of CD20+ B cell lymphomas and other B cell lymphoproliferative disorders. Its clinical efficacy might be further improved by combinations with other drugs such as statins that inhibit cholesterol synthesis and show promising antilymphoma effects. The objective of this study was to evaluate the influence of statins on rituximab-induced killing of B cell lymphomas. METHODS AND FINDINGS: Complement-dependent cytotoxicity (CDC) was assessed by MTT and Alamar blue assays as well as trypan blue staining, and antibody-dependent cellular cytotoxicity (ADCC) was assessed by a 51Cr release assay. Statins were found to significantly decrease rituximab-mediated CDC and ADCC of B cell lymphoma cells. Incubation of B cell lymphoma cells with statins decreased CD20 immunostaining in flow cytometry studies but did not affect total cellular levels of CD20 as measured with RT-PCR and Western blotting. Similar effects are exerted by other cholesterol-depleting agents (methyl-beta-cyclodextrin and berberine), but not filipin III, indicating that the presence of plasma membrane cholesterol and not lipid rafts is required for rituximab-mediated CDC. Immunofluorescence microscopy using double staining with monoclonal antibodies (mAbs) directed against a conformational epitope and a linear cytoplasmic epitope revealed that CD20 is present in the plasma membrane in comparable amounts in control and statin-treated cells. Atomic force microscopy and limited proteolysis indicated that statins, through cholesterol depletion, induce conformational changes in CD20 that result in impaired binding of anti-CD20 mAb. An in vivo reduction of cholesterol induced by short-term treatment of five patients with hypercholesterolemia with atorvastatin resulted in reduced anti-CD20 binding to freshly isolated B cells. CONCLUSIONS: Statins were shown to interfere with both detection of CD20 and antilymphoma activity of rituximab. These studies have significant clinical implications, as impaired binding of mAbs to conformational epitopes of CD20 elicited by statins could delay diagnosis, postpone effective treatment, or impair anti-lymphoma activity of rituximab.

TNF-alpha production-enhancing activity of 2-(1-adamantylamino)-6-methylpyridine (AdAMP) in cultures of human normal and neoplastic cells.

The purpose of this study was to determine the TNF-alpha-stimulatory effect of a novel immunomodulator 2-(1-adamantylamino)-6-methylpyridine (AdAMP) on normal and neoplastic human cells. In a panel of several human ovarian cancer cell lines, almost half of them spontaneously secreted significant amounts of TNF-alpha. When incubated with AdAMP, a 3-fold enhancement of TNF-alpha production by cells was observed. Furthermore, the phorbol myristic acetate ester (PMA)-induced release of TNF-alpha in cultures of U937 cells was increased in the presence of AdAMP. Primary monocytes isolated from peripheral blood did not respond to AdAMP. Although cytokine release was not triggered in human peripheral blood monocytes, AdAMP co-stimulated these cells to produce TNF-alpha and IL-8 during incubation with lipopolysaccharide (LPS). No effect of AdAMP was found on IL-1beta and IL-6 production by monocytes. In cultures of peripheral blood T lymphocytes, AdAMP significantly decreased the adhesion of these cells to matrix proteins in an in vitro assay. The results suggest that AdAMP, as a stimulator of cytokine secretion, may have potential application in tumor therapy.

Technology evaluation: HYB-2055, Hybridon.

Hybridon is developing immunomodulatory oligonucleotides. including injectable HYB-2055 (IMOxine) which acts as an agonist of toll-like receptor 9, for the potential treatment of cancer. HYB-2055 is currently undergoing phase II clinical trials. The immunomodulatory oligonucleotides are also being investigated for the potential treatment of infectious diseases and immune disorders.