IL-12 enhances the generation of tumour antigen-specific Th1 CD4 T cells during ex vivo expansion

A Phase I/II Trial of HER2 Vaccine-Primed Autologous T-Cell Infusions in Patients with Treatment Refractory HER2-Overexpressing Breast Cancer

PURPOSE

High levels of type I T cells are needed for tumor eradication. We evaluated whether the HER2-specific vaccine-primed T cells are readily expanded ex vivo to achieve levels needed for therapeutic infusion.

PATIENTS AND METHODS

Phase I/II nonrandomized trial of escalating doses of ex vivo-expanded HER2-specific T cells after in vivo priming with a multiple peptide-based HER2 intracellular domain (ICD) vaccine. Vaccines were given weekly for a total of three immunizations. Two weeks after the third vaccine, patients underwent leukapheresis for T-cell expansion, then received three escalating cell doses over 7- to 10-day intervals. Booster vaccines were administered after the T-cell infusions. The primary objective was safety. The secondary objectives included extent and persistence of HER2-specific T cells, development of epitope spreading, and clinical response. Patients received a CT scan prior to enrollment and 1 month after the last T-cell infusion.

RESULTS

Nineteen patients received T-cell infusions. Treatment was well tolerated. One month after the last T-cell infusion, 82% of patients had significantly augmented T cells to at least one of the immunizing epitopes and 81% of patients demonstrated enhanced intramolecular epitope spreading compared with baseline (P < 0.05). There were no complete responses, one partial response (6%), and eight patients with stable disease (47%), for a disease control rate of 53%. The median survival for those with progressive disease was 20.5 months and for responders (PR+SD) was 45.0 months.

CONCLUSIONS

Adoptive transfer of HER2 vaccine-primed T cells was feasible, was associated with minimal toxicity, and resulted in an increased overall survival in responding patients. See related commentary by Crosby et al., p. 3256.

Differentiation and Regulation of TH Cells: A Balancing Act for Cancer Immunotherapy

Current success of immunotherapy in cancer has drawn attention to the subsets of T_H cells in the tumor which are critical for activation of anti-tumor response either directly by themselves or by stimulating cytotoxic T cell activity. However, presence of immunosuppressive pro-tumorigenic T_H subsets in the tumor milieu further contributes to the complexity of regulation of T_H cell-mediated immune response. In this review, we present an overview of the multifaceted positive and negative effects of T_H cells, with an emphasis on regulation of different T_H cell subtypes by various immune cells, and how a delicate balance of contradictory signals can influence overall success of cancer immunotherapy. We focus on the regulatory network that encompasses dendritic cell-induced activation of CD4⁺ T_H1 cells and subsequent priming of CD8⁺ cytotoxic T cells, along with intersecting anti-inflammatory and pro-tumorigenic T_H2 cell activity. We further discuss how other tumor infiltrating immune cells such as immunostimulatory T_H9 and T_fh cells, immunosuppressive T_reg cells, and the duality of T_H17 function contribute to tip the balance of anti- vs pro-tumorigenic T_H responses in the tumor. We highlight the developing knowledge of CD4⁺ T_H1 immune response against neoantigens/oncodrivers, impact of current immunotherapy strategies on CD4⁺ T_H1 immunity, and how opposing action of T_H cell subtypes can be explored further to amplify immunotherapy success in patients. Understanding the nuances of CD4⁺ T_H cells regulation and the molecular framework undergirding the balancing act between anti- vs pro-tumorigenic T_H subtypes is critical for rational designing of immunotherapies that can bypass therapeutic escape to maximize the potential of immunotherapy.

Immunotherapy in breast cancer: Current status and future directions

Breast cancer, one of the leading causes of death in women in the United States, challenges therapeutic success in patients due to tumor heterogeneity, treatment resistance, metastasis and disease recurrence. Knowledge of immune system involvement in normal breast development and breast cancer has led to extensive research into the immune landscape of breast cancer and multiple immunotherapy clinical trials in breast cancer patients. However, poor immunogenicity and T-cell infiltration along with heightened immunosuppression in the tumor microenvironment have been identified as potential challenges to the success of immunotherapy in breast cancer. Oncodrivers, owing to their enhanced expression and stimulation of tumor cell proliferation and survival, present an excellent choice for targeted immunotherapy development in breast cancer. Loss of anti-tumor immune response specific to oncodrivers has been reported in breast cancer patients as well. Dendritic cell vaccines have been tested for their efficacy in generating anti-tumor T-cell response against specific tumor-associated antigens and oncodrivers and have shown improved survival outcome in patients. Here, we review the current status of immunotherapy in breast cancer, focusing on dendritic cell vaccines and their therapeutic application in breast cancer. We further discuss future directions of breast cancer immunotherapy and potential combination strategies involving dendritic cell vaccines and existing chemotherapeutics for improved efficacy and better survival outcome in breast cancer.

Combination of dual mTORC1/2 inhibition and immune-checkpoint blockade potentiates anti-tumour immunity

mTOR inhibition can promote or inhibit immune responses in a context dependent manner, but whether this will represent a net benefit or be contraindicated in the context of immunooncology therapies is less understood. Here, we report that the mTORC1/2 dual kinase inhibitor vistusertib (AZD2014) potentiates anti-tumour immunity in combination with anti-CTLA-4 (αCTLA-4), αPD-1 or αPD-L1 immune checkpoint blockade. Combination of vistusertib and immune checkpoint blocking antibodies led to tumour growth inhibition and improved survival of MC-38 or CT-26 pre-clinical syngeneic tumour models, whereas monotherapies were less effective. Underlying these combinatorial effects, vistusertib/immune checkpoint combinations reduced the occurrence of exhausted phenotype tumour infiltrating lymphocytes (TILs), whilst increasing frequencies of activated Th1 polarized T-cells in tumours. Vistusertib alone was shown to promote a Th1 polarizing proinflammatory cytokine profile by innate primary immune cells. Moreover, vistusertib directly enhanced activation of effector T-cell and survival, an effect that was critically dependent on inhibitor dose. Therefore, these data highlight direct, tumour-relevant immune potentiating benefits of mTOR inhibition that complement immune checkpoint blockade. Together, these data provide a clear rationale to investigate such combinations in the clinic.

Surrogate in vitro activation of innate immunity synergizes with interleukin-7 to unleash rapid antigen-driven outgrowth of CD4+ and CD8+ human peripheral blood T-cells naturally recognizing MUC1, HER2/neu and other tumor-associated antigens

Effective adoptive immunotherapy has proved elusive for many types of human cancer, often due to difficulties achieving robust expansion of natural tumor-specific T-cells from peripheral blood. We hypothesized that antigen-driven T-cell expansion might best be triggered in vitro by acute activation of innate immunity to mimic a life-threatening infection. Unfractionated peripheral blood mononuclear cells (PBMC) were subjected to a two-step culture, first synchronizing their exposure to exogenous antigens with aggressive surrogate activation of innate immunity, followed by γ-chain cytokine-modulated T-cell hyperexpansion. Step 1 exposure to GM-CSF plus paired Toll-like receptor agonists (resiquimod and LPS), stimulated abundant IL-12 and IL-23 secretion, as well as upregulated co-stimulatory molecules and CD11c expression within the myeloid (CD33+) subpopulation. Added synthetic long peptides (>20aa) derived from widely expressed oncoproteins (MUC1, HER2/neu and CMVpp65), were reliably presented to CD4+ T-cells and cross-presented to CD8+ T-cells. Both presentation and cross-presentation demonstrated proteasomal and Sec61 dependence that could bypass the endoplasmic reticulum. Step 2 exposure to exogenous IL-7 or IL-7+IL-2 produced selective and sustained expansion of both CD4+ and CD8+ peptide-specific T-cells with a predominant interferon-γ-producing T1-type, as well as the antigen-specific ability to lyse tumor targets. Other γ-chain cytokines and/or combinations were initially proliferogenic, but followed by a contractile phase not observed with IL-7 or IL-7+IL-2. Regulatory T-cells were minimally propagated under these culture conditions. This mechanistically rational culture sequence, effective even for unvaccinated donors, enables rapid preparation of T-cells recognizing tumor-associated antigens expressed by the majority of human cancers, including pancreatic cancers, breast cancers and glioblastomas.

The Antitumor Efficacy of IL2/IL21-Cultured Polyfunctional Neu-Specific T Cells Is TNFα/IL17 Dependent

PURPOSE

Infusion of HER2-specific T cells, derived from vaccine-primed patients and expanded with IL2/IL12, has induced tumor regression in a minority of patients with metastatic treatment-refractory HER2(+) breast cancer. We questioned whether alteration of cytokine growth factors used to culture vaccine-primed T cells could improve antitumor activity.

EXPERIMENTAL DESIGN

Using the TgMMTV-neu murine mammary tumor model, we cultured T cells derived from mice immunized with a previously defined neu class II peptide, p98-114 (neu p98), and evaluated different cytokine combinations for expansion.

RESULTS

Infusion of neu p98-specific T-cell lines derived from all cytokine conditions evaluated resulted in significant antitumor activity compared with infused naïve splenocytes (P < 0.05). T cells cultured with IL2/IL21 could uniquely mediate complete regression of spontaneous mammary tumors. IL2/IL21 cultured neu-specific T cells demonstrated a different cytokine secretion pattern as compared with other cultured T cells; secreting high levels of TNFα and IL17 (P < 0.05). Moreover, tumor-infiltrating CD8(+) cells were significantly increased after the infusion of IL2/IL21 cultured T cells as compared with tumors treated with T cells expanded under other cytokine conditions (P < 0.001). The antitumor effect of the infusion of IL2/IL21 cultured cells was mediated by CD8 T cells. Depletion of TNFα or IL17, but not IFNγ, abrogated the tumor growth inhibition induced by the IL2/IL21 T cells and markedly decreased the influx of CD8 into tumors. Finally, IL2/IL21-cultured human antigen specific T cells also displayed a similar polyfunctional Th1/Th17 phenotype.

CONCLUSIONS

Expansion of HER2 vaccine-primed T cells with IL2/IL21 may have the potential to effectively mediate tumor regression when used in adoptive transfer. Clin Cancer Res; 22(9); 2207-16. ©2015 AACR.

Regular tai chi exercise decreases the percentage of type 2 cytokine-producing cells in postsurgical non-small cell lung cancer survivors

BACKGROUND

Tai Chi combines aspects of meditation and aerobic exercise. Its effect on the balance between cellular and humoral immunity, which potentiates human immunity against tumors, remains to be determined.

OBJECTIVE

The objective was to investigate the effect of a 16-week Tai Chi exercise intervention on the recovery of postsurgical non-small cell lung cancer survivors.

INTERVENTIONS/METHODS

A controlled study was performed in 32 lung cancer survivors who practiced Tai Chi during a 16-week period. The percentages of interferon γ-producing CD3 T lymphocyte cells (T1) and interleukin 4-producing CD3 T lymphocyte cells (T2) and CD3 T lymphocyte subsets (T helper cell type 1 [TH1], TH2; cytotoxic T cell type 1 [Tc1], Tc2) were determined as well as levels of hormones β-endorphin, general catecholamines, and cortisol.

RESULTS

Whereas the T1/T2 and Tc1/Tc2 ratios in the control group decreased in the natural course of postsurgical non-small cell lung cancer recovery (both P < .01), no changes were observed in the Tai Chi group. The differences in changes in the T1/T2 and Tc1/Tc2 ratios (both P < .01) and in T2 and Tc2 levels (P < .01) between the 2 groups were significant. The cortisol level increased in the control group (P < .05) but not in Tai Chi group.

CONCLUSIONS

A 16-week Tai Chi exercise significantly diminished the magnitude of the decreased T1/T2 ratio in the natural course of recovery in a population of postsurgical non-small cell lung cancer survivors.

IMPLICATIONS FOR PRACTICE

Tai Chi may have a role in ameliorating the imbalance between humoral and cellular immunity, potentiating human immunity against tumors.

HER-2/neu vaccine-primed autologous T-cell infusions for the treatment of advanced stage HER-2/neu expressing cancers

This phase I study evaluated the feasibility of expanding HER-2/neu (HER2) vaccine-primed peripheral blood T-cells ex vivo and assessed the safety of T-cell infusions. Eight patients with HER2(+) treatment refractory metastatic cancers were enrolled. T-cells could be expanded to predefined parameters in seven patients (88%). Ninety-two percent of adverse events were grade 1 or 2. Three of seven patients developed infusion-related inflammatory reactions at their disease sites. HER2-specific T-cells significantly increased in vivo compared to pre-infusion levels (p = 0.010) and persisted in 4/6 patients (66%) over 70 days after the first infusion. Partial clinical responses were observed in 43% of patients. Levels of T-regulatory cells in peripheral blood prior to infusion (p < 0.001), the level of HER2-specific T-cells in vivo (p = 0.030), and development of diverse clonal T-cell populations (p < 0.001) were associated with response. The generation of HER2 vaccine-primed autologous T-cells for therapeutic infusion is feasible and well tolerated. This approach provides a foundation for the application of T-cell therapy to additional solid tumor types.

The role of interleukin-12 on modulating myeloid-derived suppressor cells, increasing overall survival and reducing metastasis

Myeloid-derived suppressor cells (MDSC) are important to the tumour microenvironment as they actively suppress the immune system and promote tumour progression and metastasis. These cells block T-cell activation in the tumour microenvironment, preventing anti-tumour immune activity. The ability of a treatment to alter the suppressive function of these cells and promote an immune response is essential to enhancing overall therapeutic efficacy. Interleukin-12 (IL-12) has the potential not only to promote anti-tumour immune responses but also to block the activity of cells capable of immune suppression. This paper identifies a novel role for IL-12 as a modulator of MDSC activity, with implications for IL-12 as a therapeutic agent. Treatment with IL-12 was found to alter the suppressive function of MDSC by fundamentally altering the cells. Interleukin-12-treated MDSC exhibited up-regulation of surface markers indicative of mature cells as well as decreases in nitric oxide synthase and interferon-γ mRNA both in vitro and in vivo. Treatment with IL-12 was also found to have significant therapeutic benefit by decreasing the percentage of MDSC in the tumour microenvironment and increasing the percentage of active CD8(+) T cells. Treatment with IL-12 resulted in an increase in overall survival accompanied by a reduction in metastasis. The findings in this paper identify IL-12 as a modulator of immune suppression with significant potential as a therapeutic agent for metastatic breast cancer.

Antitumor mechanism of recombinant murine interleukin-12 vaccine

This study was designed to establish an interleukin-12 (IL-12)-expressing murine Lewis lung carcinoma (LLC) cell vaccine (LLC/murine IL-12 [mIL-12]) and assess its antitumor efficacy and mechanism in vivo. The recombinant IL-12 plasmid was transfected into LLC cells and screened by G418, and positive clones were obtained. C57BL/6 tumor-bearing mouse model was established and tumor-bearing mice were randomly divided into three groups (n = 20), that is, treated with an intratumoral injection of phosphate-buffered solution, blank plasmid, or LLC/mIL-12 vaccine, respectively, at days 0, 7, and 14. Tumor size was measured before and after treatment. Tumor growth curve was plotted, cytolytic T lymphocyte (CTL) activity assay and natural killer (NK) cell activity assay were performed, CD4(+) and CD8(+) T lymphocyte were quantitated using flow cytometry, and the expression of interferon-gamma (IFN-gamma), IL-12, and interferon-inducible protein-10 (IP-10) in serum was detected by ELISA. Microvessel density was determined by immunohistochemistry after all mice were euthanized at day 21. The study revealed suppressed tumor growth, elevated levels of IFN-gamma, IP-10, and IL-12, augmented NK and CTL cell activities, and decreased microvessel density of tumor tissues. There were abundant CD4(+) and CD8(+) T lymphocyte infiltration in the vaccine group. This study demonstrated that the antitumor mechanism of LLC/mIL-12 vaccine was to promote IFN-gamma and IL-12 secretion, augment the NK and CTL cell activities, and decrease the microvessel density of tumors.

Enhancement of antitumor activity of gammaretrovirus carrying IL-12 gene through genetic modification of envelope targeting HER2 receptor: a promising strategy for bladder cancer therapy

The objective of this study was to develop an HER2-targeted, envelope-modified Moloney murine leukemia virus (MoMLV)-based gammaretroviral vector carrying interleukin (IL)-12 gene for bladder cancer therapy. It displayed a chimeric envelope protein containing a single-chain variable fragment (scFv) antibody to the HER2 receptor and carried the mouse IL-12 gene. The fragment of anti-erbB2scFv was constructed into the proline-rich region of the viral envelope of the packaging vector lacking a transmembrane subunit of the carboxyl terminal region of surface subunit. As compared with envelope-unmodified gammaretroviruses, envelope-modified ones had extended viral tropism to human HER2-expressing bladder cancer cell lines, induced apoptosis, and affected cell cycle progression despite lower viral titers. Moreover, animal studies showed that envelope-modified gammaretroviruses carrying IL-12 gene exerted higher antitumor activity in terms of retarding tumor growth and prolonging the survival of tumor-bearing mice than unmodified ones, which were associated with enhanced tumor cell apoptosis as well as increased intratumoral levels of IL-12, interferon-gamma, IL-1beta, and tumor necrosis factor-alpha proteins. Therefore, the antitumor activity of gammaretroviruses carrying the IL-12 gene was enhanced through genetic modification of the envelope targeting HER2 receptor, which may be a promising strategy for bladder cancer therapy.

Synergistic antitumor effects of 131I-LC-1 IgM and IL-12 vaccine on Lewis lung carcinoma

This study was designed to determine the antitumor effects of iodine-131 labeled monoclonal antibody LC-1 ((131)I-LC-1), interleukin-12 (IL-12) vaccine, or the combination of both on C57BL/6 mice bearing Lewis lung carcinoma (LLC) tumors. Tumor-bearing mice models were randomly divided into 4 groups that were respectively injected intratumorally with phosphate buffered solution (PBS), IL-12 vaccine gene therapy (GT), (131)I-LC-1 radioimmuno-therapy (RIT), or GT+RIT. Tumor volumes were measured before and after treatment. ELISA and RT-PCR determined the expression of IL-l2. LC-1 monoclonal antibody (Mab) was labeled with Na(131)I. Cytolytic T lymphocyte (CTL) activity assay, Natural Killer cell (NK) activity assay and apoptosis analysis were performed. Intratumoral (131)I-LC-1 injection leads to higher delivery of the antibody to the tumor. Tumor apoptosis occurred in the GT, RIT and GT+RIT groups. Tumor growth was inhibited in the GT, RIT and GT+RIT groups. Compared with other groups, the combination of GT+RIT up-regulated the expression of IL-l2 gene and inhibited the tumor growth more effectively than either GT or RIT alone (p<0.05). These results suggest that GT+RIT have the synergistic antitumor effects on tumor-bearing mice.

Immunomodulation of breast cancer via tumor antigen specific Th1

It has long been assumed that the immune system plays a role in tumor eradication, however, scant clinical evidence exists to support that hypothesis. In recent years, as the immune system and its specific effector cells are better defined, convincing data supporting immune surveillance is emerging. Several studies have shown that an "immune signature" in the tumor microenvironment is associated with a superior outcome in a variety of cancer types. Moreover, studies have suggested that T cells found in high density within the tumor parenchyma are also correlated with a survival benefit. The type of adaptive immune response implicated in improved cancer outcomes is a type 1 response. That is, adaptive immunity associated with T cells that secrete pro-inflammatory cytokines, such as IFN-gamma, which can not only support a proliferative antigen specific T cell response but also enhance "cross priming" by activating antigen presenting cells local to the tumor site. There are many methods available that will allow the development of clinical reagents designed to stimulate Th1 immunity; either by in vitro or in vivo manipulation. Clinical trials of a variety of immunotherapeutic strategies indicate that the generation of tumor antigen specific Th1 may be beneficial in inhibiting the growth of common solid tumors.

Reproducibility and correlations of multiplex cytokine levels in asymptomatic persons

RATIONALE

Cytokines are humoral regulatory molecules that act together in immunologic pathways underlying pathogenesis. Grossly elevated blood levels characterize certain diseases; variations within physiologic ranges could also have significance. We therefore evaluated the performance characteristics of a multiplex cytokine immunoassay.

METHODS

We used a fluorescent bead-based (Luminex) immunoassay kit to simultaneously measure interleukin (IL) 1beta, IL2, IL4, IL5, IL6, IL7, IL8, IL10, IL12p70, IL13, IFNgamma, granulocyte colony-stimulating factor, and tumor necrosis factor-alpha. We tested identical aliquots of serum from 38 asymptomatic individuals on three different days and matched sets of serum, heparinized plasma, and acid citrate dextrose plasma from an additional 38 healthy donors expected to have low cytokine concentrations. We applied multiple imputation to calculate unbiased reproducibility estimates for measurements below the limits of detection. Correlations among the cytokines were assessed by Spearman rank order coefficients and principal components analyses.

RESULTS

Of the 13 cytokines, 3 were undetectable (IL1beta, IL2, IL5) in more than half of the serum samples. Coefficients of variation for replicate serum measurements ranged from 18% to 44%, with intraclass correlation coefficients ranging from 55% to 98%. Only IL4, IL6, and IL8 had statistically significant correlations (Spearman rho, 0.42-0.94) between serum and acid citrate dextrose or heparin plasma levels.

CONCLUSIONS

Interindividual differences outweigh substantial laboratory variation for these assays, yielding high intraclass correlation coefficients despite unimpressive coefficients of variation. Plasma measurements generally are not reflective of serum levels and hence are not interchangeable. With their small volume, low cost per test, and multiplex capacity, Luminex-based cytokine assays have potential utility for epidemiologic studies.

Permanent silencing of NKG2A expression for cell-based therapeutics

Natural killer (NK) and T-cell cytotoxicity is significantly reduced by signaling via CD94/NKG2A receptors. High levels of NKG2A on NK cells have been shown to compromise the graft-versus-leukemia effect in hematopoietic stem cell transplantation. We therefore evaluated the functional relevance of NKG2A silencing for the cytotoxic potential of genetically engineered NK and T cells. Lentiviral vectors containing short hairpin RNA (shRNA) sequences targeting NKG2A transcripts were used to transduce NKG2A(+) primary NK and T cells. NKG2A expression levels were measured by flow cytometry and real-time PCR. The effect of NKG2A silencing on the cytolytic potential of NK and T cells was evaluated in cytotoxicity assays using K562 and B lymphoblastoid cells as targets. Granzyme B mRNA transcript levels were detected by real-time PCR. The transduction of inducible RNAi cassettes containing the sequences for shRNAs targeting NKG2A reduced protein expression in NK and T cells by up to 95%. The cytotoxicity assays demonstrated that NKG2A silencing effectively enhanced NK and CD8+ T-cell lysis by up to 40% and 15%, respectively. However, lysis of K562 cells which lack human leukocyte antigen-E, the ligand of NKG2A, was associated with an upregulation of the natural cytotoxicity receptor NKp30 in NKG2A-silenced NK cells. Our data suggest that RNAi-mediated silencing of NKG2A in effector cells could improve the efficacy of cell-based immunotherapies but also show that indirect effects of NKG2A knockdown exist that have to be considered when designing therapeutic protocols with genetically engineered NK or T cells.

Insulin-like growth factor-binding protein-2 is a target for the immunomodulation of breast cancer

Breast cancer is immunogenic and well suited to treatment via immunomodulation. The disease is often treated to remission and time to relapse is generally measured in years in many cases. Immune-based therapeutics, such as cancer vaccines, may be able to affect the clinical progression of micrometastatic disease. Immune targets must be identified that have the potential to inhibit tumor growth. Insulin-like growth factor-binding protein-2 (IGFBP-2) has direct effects on breast cancer proliferation via stimulation of critical signaling pathways. We questioned whether IGFBP-2 was an immune target in breast cancer. IGFBP-2-specific IgG antibody immunity was preferentially detected in breast cancer patients compared with controls (P = 0.0008). To evaluate for the presence of T-cell immunity, we identified potential pan-HLA-DR binding epitopes derived from IGFBP-2 and tested the peptides for immunogenicity. The majority of epitopes elicited peptide-specific T cells in both patients and controls and had high sequence homology to bacterial pathogens. IGFBP-2 peptide-specific T cells could respond to naturally processed and presented IGFBP-2 protein, indicating that these peptides were native epitopes of IGFBP-2. Finally, both immunization with IGFBP-2 peptides as well as adoptive transfer of IGFBP-2-competent T cells mediated an antitumor effect in a transgenic mouse model of breast cancer. This is the first report of IGFBP-2 as a human tumor antigen that may be a functional therapeutic target in breast cancer.

Peripheral blood dendritic cell subsets from patients with monoclonal gammopathies show an abnormal distribution and are functionally impaired

Objectives. The information currently available about dendritic cells (DCs) in patients with different types of monoclonal gammopathy (MG) is limited and frequently controversial. In the present study, we analyzed the ex vivo distribution as well as the phenotypic and functional characteristics of peripheral blood (PB) DCs from different types of MG. Methods. For this purpose, 61 untreated patients in total with MG were analyzed-MG of undetermined significance (MGUS), 29 cases; multiple myeloma (MM), 28 cases; and plasma cell leukemia (PCL), 4 cases-in comparison with a group of 10 healthy controls. Results. Our results show an absolute overall higher number of all subsets of PB DCs in PCL, together with lower numbers of myeloid DCs in MM patients. From a phenotypic point of view, PB DC subsets from all types of MG expressed significantly higher levels of HLA molecules and altered patterns of expression of the CD2, CD11c, CD16, CD22, CD62L, and CD86 molecules, in association with altered patterns of secretion of inflammatory cytokines. Conclusion. In summary, we show the existence of significant abnormalities in the distribution, phenotype, and pattern of secretion of inflammatory cytokines by different subsets of PB DCs from patients with MGs, which could reflect a potentially altered homing of DCs, together with a greater in vivo activation and lower responsiveness of PB DCs, which are already detectable in MGUS patients.

The endogenous danger signal, crystalline uric acid, signals for enhanced antibody immunity

Studies have shown that the immune system can recognize self-antigens under conditions (eg, cell injury) in which the self-tissue might elaborate immune-activating endogenous danger signals. Uric acid (UA) is an endogenous danger signal recently identified to be released from dying cells. Prior work has shown that UA activates immune effectors of both the innate and adaptive immune system, including neutrophils and cytotoxic T-cell immunity. However, it was unclear whether UA could enhance antibody immunity, which was examined in this study. When added to dying tumor cells or with whole protein antigen, UA increased IgG1-based humoral immunity. Further, UA blocked growth of tumor in subsequent tumor challenge experiments, which depended on CD4, but not CD8, T cells. Sera derived from UA-treated animals enhanced tumor growth, suggesting it had little role in the antitumor response. UA did not signal for T-cell expansion or altered tumor-infiltrating leukocyte populations. Consistent with the lack of T-cell expansion, when applied to dendritic cells, UA suppressed T-cell growth factors but up-regulated B cell-activating cytokines. Understanding the nature of endogenous danger signals released from dying cells may aid in a better understanding of mechanisms of immune recognition of self.

Tumor Antigen–Specific T-Cell Expansion Is Greatly Facilitated by In vivo Priming

PURPOSE

Adoptive T-cell therapy is a promising strategy for the treatment of patients with established tumors but is often limited to specific cancers where tumor-infiltrating lymphocytes, the source of T cells for ex vivo culture, can be obtained. In this study, we evaluated the feasibility of expanding HER-2/neu-specific T cells derived from peripheral blood ex vivo following in vivo priming with a HER-2/neu peptide vaccine.

EXPERIMENTAL DESIGN

Peripheral blood mononuclear cells from cytomegalovirus (CMV)-seronegative and CMV-seropositive donors as well as HER-2/neu-positive cancer patients who had or had not been vaccinated with a HER-2/neu peptide-based vaccine was used as a source of T lymphocytes. Antigen-specific T-cell lines were generated by in vitro stimulation with antigen followed by nonspecific expansion on CD3/CD28 beads. The ability to expand antigen-specific T cells was assessed using IFN-gamma and granzyme B enzyme-linked immunosorbent spot. The phenotype of the resultant T-cell lines was evaluated by flow cytometry, including the presence of FOXP3-expressing CD4(+) T cells.

RESULTS

The frequencies of CMV-specific T cells generated from CMV(+) donors were >11-fold higher than the frequencies from CMV(-) donors (P = 0.001), with 22-fold increase of total number of CD3(+) T cells. The frequencies of HER-2/neu-specific T cells generated from the primed patients were >25-fold higher than the frequencies from unvaccinated patients (P = 0.006), with an average of a 19-fold increase of total number of CD3(+) T cells. Using peripheral blood as the source of T cells did not result in concurrent expansion of FOXP3(+)CD4(+) regulatory T cells despite the use of interleukin-2 in in vitro culture. Both CD4(+) and CD8(+) HER-2/neu-specific T cells could be expanded. The extent of ex vivo expansion correlated with the magnitude of immunity achieved during immunization (P = 0.008).

CONCLUSION

Tumor-specific T cells can be efficiently expanded from the peripheral blood ex vivo following in vivo priming with a vaccine. This approach provides an effective method to generate tumor-specific polyclonal T cells for therapeutic use that could be applied to cancer patients with any tumor type.

Assessing responses to cancer therapy using molecular imaging

Tumor responses to therapy in the clinic are still evaluated primarily from non-invasive imaging measurements of reductions in tumor size. This approach, however, lacks sensitivity and can only give a delayed indication of a positive response to treatment. Major advances in our understanding of the molecular mechanisms responsible for cancer, combined with new targeted clinical imaging technologies designed to detect the molecular correlates of disease progression and response to treatment, are set to revolutionize our approach to the detection and treatment of the disease. We describe here the imaging technologies available to image tumor cell proliferation and migration, metabolism, receptor and gene expression, apoptosis and tumor angiogenesis and vascular function, and show how measurements of these parameters can be used to give early indications of positive responses to treatment or to detect drug resistance and/or disease recurrence. Special emphasis has been placed on those applications that are already used in the clinic and those that are likely to translate into clinical application in the near future or whose use in preclinical studies is likely to facilitate translation of new treatments into the clinic.

Immunoediting of cancers may lead to epithelial to mesenchymal transition

Tumors evade both natural and pharmacologically induced (e.g., vaccines) immunity by a variety of mechanisms, including induction of tolerance and immunoediting. Immunoediting results in reshaping the immunogenicity of the tumor, which can be accompanied by loss of Ag expression and MHC molecules. In this study, we evaluated immunoediting in the neu-transgenic mouse model of breast cancer. A tumor cell line that retained expression of rat neu was generated from a spontaneous tumor of the neu-transgenic mouse and, when injected into the non-transgenic parental FVB/N mouse, resulted in the development of a strong immune response, initial rejection, and ultimately the emergence of neu Ag-loss variants. Morphologic and microarray data revealed that the immunoedited tumor cells underwent epithelial to mesenchymal transition accompanied by an up-regulation of invasion factors and increased invasiveness characteristic of mesenchymal tumor cells. These results suggest that immunoediting of tumor results in cellular reprogramming may be accompanied by alterations in tumor characteristics including increased invasive potential. Understanding the mechanisms by which tumors are immunoedited will likely lead to a better understanding of how tumors evade immune detection.

IL-2 immunotoxin therapy modulates tumor-associated regulatory T cells and leads to lasting immune-mediated rejection of breast cancers in neu-transgenic mice

Studies in cancer patients have suggested that breast tumors recruit regulatory T cells (Tregs) into the tumor microenvironment. The extent to which local Tregs suppress antitumor immunity in breast cancer is unknown. We questioned whether inhibiting systemic Tregs with an IL-2 immunotoxin in a model of neu-mediated breast cancer, the neu-transgenic mouse, could impact disease progression and survival. As in human breast cancer, cancers that develop in these mice attract Tregs into the tumor microenvironment to levels of approximately 10-25% of the total CD4+ T cells. To examine the role of Tregs in blocking immune-mediated rejection of tumor, we depleted CD4+CD25+ T cells with an IL-2 immunotoxin. The treatment depleted Tregs without concomitant lymphopenia and markedly inhibited tumor growth. Depletion of Tregs resulted in a persistent antitumor response that was maintained over a month after the last treatment. The clinical response was immune-mediated because adoptive transfer of Tregs led to a complete abrogation of the therapeutic effects of immunotoxin treatment. Further, Treg down-modulation was accompanied by increased Ag-specific immunity against the neu protein, a self Ag. These results suggest that Tregs play a major role in preventing an effective endogenous immune response against breast cancer and that depletion of Tregs, without any additional immunotherapy, may mediate a significant antitumor response.

Adoptive T cell therapy of solid cancers

The development of immune-based approaches for the treatment of cancer has been actively investigated for many years. One strategy that has emerged as a potentially effective strategy for the treatment of aggressive established malignancies is adoptive T cell therapy. The power of this approach has been repeatedly observed in preclinical animal models. However, moving from homogeneous animal models to the heterogeneous human clinical setting has been very difficult. It is only in recent times that we have been able to pinpoint the problems of the clinical translation of adoptive T cell therapy. Some of the major problems are sources of tumor-specific T cells, ex vivo expansion, persistence, and anti-tumor activity. This review overviews the nature of these problems and some of the emerging solutions.

Melanoma skews dendritic cells to facilitate a T helper 2 profile

BACKGROUND

Patients with progressing melanoma have a circulating cytokine profile reflecting a T helper cell type 2 (Th2) imbalance, while patients responding to therapy favor a Th1 profile. The aim of this study was to determine the role of circulating dendritic cells (DCs) in mediating this imbalance.

METHODS

Isolated human peripheral blood mononuclear cells (PBMCs) were exposed to cell-free melanoma-conditioned medium (MCM) or control fibroblast-conditioned medium before stimulation. In separate experiments, isolated circulating DCs were exposed to MCM before addition of T cells. DC maturation and function were determined. Mixed leukocyte response T-cell proliferation was quantified and supernatants were assayed for Th1 (interleukin [IL]-2 and interferon gamma) and Th2 (IL-4, IL-5, and IL-10) cytokines.

RESULTS

PBMCs exposed to MCM produced significantly more Th2-type cytokines (IL-4, IL-5, and IL-10) over time than those exposed to control medium. DCs exposed to MCM before addition of T cells, produced a similar pattern of a sustained longer term Th2 response after an initial burst of IL-2. Exposure to MCM did not significantly affect DC maturation or IL-12 production. T-cell proliferation did not change significantly in the mixed leukocyte response, however, the percentage of viable CD4+ T cells in the MCM-treated group was significantly less than control (37 vs 50%, P < .05).

CONCLUSIONS

Exposure of PBMCs to melanoma produces a Th2-type cytokine profile, which may be, in part, facilitated by DCs.

Prolonged Culture of Vaccine-Primed Lymphocytes Results in Decreased Antitumor Killing and Change in Cytokine Secretion

Adoptive transfer of effector T cells has been used successfully to eliminate metastases in animal models. Because antitumor activity depends on the number of effector cells transferred, some human trials have used in vitro-repetitive activation and expansion techniques to increase cell number. We hypothesized that the prolonged culture period might contribute to the lack of human trial success by decreasing the potency of the effector T cells. Lymph nodes draining a progressively growing murine melanoma tumor transduced to secrete granulocyte/macrophage colony-stimulating factor were harvested and activated in vitro with anti-CD3 monoclonal antibody followed by expansion in IL-2 for a total of 5 days in culture. Some lymphocytes were reactivated and further expanded for a total of 9 days in culture. In vivo activity of the effector T cells was measured by the reduction in lung metastases and is shown to be dose dependent. The prolonged culture period resulted in nearly 3-fold more T cells but at least 8-fold less antitumor activity. This was accompanied by decreased secretion of the proinflammatory cytokine, IFN-gamma, and increased secretion of the anti-inflammatory cytokine, IL-10. Thus, although increased cell number is important to maximize the effectiveness of adoptive immunotherapy, some culture conditions may actually be counterproductive in that decreases in cell potency can outweigh the benefits of increased cell numbers. The T-cell cytokine secretion pattern predicts decreased effector cell function and may explain the decreased antitumor effect.