Vaccination with irradiated autologous tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor augments antitumor immunity in some patients with metastatic non-small-cell lung carcinoma

Effect of granulocyte/macrophage colony-stimulating factor on circulating CD8+ and CD4+ T-cell responses to a multipeptide melanoma vaccine: outcome of a multicenter randomized trial

PURPOSE

Granulocyte/macrophage colony-stimulating factor (GM-CSF) administered locally together with vaccines can augment T-cell responses in animal models. Human experience has been limited to small and uncontrolled trials. Thus, a multicenter randomized phase II trial was done to determine whether local administration of GM-CSF augments immunogenicity of a multipeptide vaccine. It also assessed immunogenicity of administration in one versus two vaccine sites.

EXPERIMENTAL DESIGN

One hundred twenty-one eligible patients with resected stage IIB to IV melanoma were vaccinated with 12 MHC class I-restricted melanoma peptides to stimulate CD8+ T cells plus a HLA-DR-restricted tetanus helper peptide to stimulate CD4+ T cells, emulsified in incomplete Freund's adjuvant, with or without 110 microg GM-CSF. Among 119 evaluable patients, T-cell responses were assessed by IFN-gamma ELIspot assay and tetramer analysis. Clinical outcomes were recorded.

RESULTS

CD8+ T-cell response rates to the 12 MHC class I-restricted melanoma peptides (by day 50) with or without GM-CSF were 34% and 73%, respectively (P < 0.001), by direct ELIspot assay. Tetramer analyses corroborated the functional data. CD4+ T-cell responses to tetanus helper peptide were higher without GM-CSF (95% versus 77%; P = 0.005). There was no significant difference by number of vaccine sites. Three-year overall and disease-free survival estimates (95% confidence interval) were 76% (67-83%) and 52% (43-61%), respectively, with too few events to assess differences by study group.

CONCLUSIONS

High immune response rates for this multipeptide vaccine were achieved, but CD8+ and CD4+ T-cell responses were lower when administered with GM-CSF. These data challenge the value of local GM-CSF as a vaccine adjuvant in humans.

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting cellular immunotherapy in combination with autologous stem cell transplantation (ASCT) as postremission therapy for acute myeloid leukemia (AML)

Preclinical models have demonstrated the efficacy of granulocyte-macrophage colony-stimulating factor-secreting cancer immunotherapies (GVAX platform) accompanied by immunotherapy-primed lymphocytes after autologous stem cell transplantation in hematologic malignancies. We conducted a phase 2 study of this combination in adult patients with acute myeloid leukemia. Immunotherapy consisted of autologous leukemia cells admixed with granulocyte-macrophage colony-stimulating factor-secreting K562 cells. "Primed" lymphocytes were collected after a single pretransplantation dose of immunotherapy and reinfused with the stem cell graft. Fifty-four subjects were enrolled; 46 (85%) achieved a complete remission, and 28 (52%) received the pretransplantation immunotherapy. For all patients who achieved complete remission, the 3-year relapse-free survival (RFS) rate was 47.4% and overall survival was 57.4%. For the 28 immunotherapy-treated patients, the RFS and overall survival rates were 61.8% and 73.4%, respectively. Posttreatment induction of delayed-type hypersensitivity reactions to autologous leukemia cells was associated with longer 3-year RFS rate (100% vs 48%). Minimal residual disease was monitored by quantitative analysis of Wilms tumor-1 (WT1), a leukemia-associated gene. A decrease in WT1 transcripts in blood was noted in 69% of patients after the first immunotherapy dose and was also associated with longer 3-year RFS (61% vs 0%). In conclusion, immunotherapy in combination with primed lymphocytes and autologous stem cell transplantation shows encouraging signals of potential activity in acute myeloid leukemia (ClinicalTrials.gov: NCT00116467).

Biologic activity of irradiated, autologous, GM-CSF-secreting leukemia cell vaccines early after allogeneic stem cell transplantation

Through an immune-mediated graft-versus-leukemia effect, allogeneic hematopoietic stem cell transplantation (HSCT) affords durable clinical benefits for many patients with hematologic malignancies. Nonetheless, subjects with high-risk acute myeloid leukemia or advanced myelodysplasia often relapse, underscoring the need to intensify tumor immunity within this cohort. In preclinical models, allogeneic HSCT followed by vaccination with irradiated tumor cells engineered to secrete GM-CSF generates a potent antitumor effect without exacerbating the toxicities of graft-versus-host disease (GVHD). To test whether this strategy might be similarly active in humans, we conducted a Phase I clinical trial in which high-risk acute myeloid leukemia or myelodysplasia patients were immunized with irradiated, autologous, GM-CSF-secreting tumor cells early after allogeneic, nonmyeloablative HSCT. Despite the administration of a calcineurin inhibitor as prophylaxis against GVHD, vaccination elicited local and systemic reactions that were qualitatively similar to those previously observed in nontransplanted, immunized solid-tumor patients. While the frequencies of acute and chronic GVHD were not increased, 9 of 10 subjects who completed vaccination achieved durable complete remissions, with a median follow-up of 26 months (range 12-43 months). Six long-term responders showed marked decreases in the levels of soluble NKG2D ligands, and 3 demonstrated normalization of cytotoxic lymphocyte NKG2D expression as a function of treatment. Together, these results establish the safety and immunogenicity of irradiated, autologous, GM-CSF-secreting leukemia cell vaccines early after allogeneic HSCT, and raise the possibility that this combinatorial immunotherapy might potentiate graft-versus-leukemia in patients.

GM-CSF Gene-Modifed Cancer Cell Immunotherapies: Of Mice and Men

GVAX cancer immunotherapies are composed of whole tumor cells genetically modified to secrete the immune stimulatory cytokine, granulocyte-macrophage colony-stimulating factor (GM-CSF), and then irradiated to prevent further cell division. Both autologous (patient specific) and allogeneic (non-patient specific) GVAX platforms have been evaluated either as single agents or in combination with other immunomodulatory strategies. Many early-phase clinical trials have now been completed. Results have consistently demonstrated a favorable safety profile manifested primarily by injection site reactions and flu-like symptoms. Consistent evidence of immune activation and clinical activity, including radiologic tumor regressions, has been seen across multiple cancer indications in both early- and late-stage disease. Phase 3 trials evaluating an allogeneic GVAX immunotherapy product in prostate cancer are under way.

Cytokine gene-mediated immunotherapy: current status and future perspectives

Recent understanding of the molecular events crucial in overcoming immunosuppressive tumor microenvironments and generating effective antitumor immunity provides us with the wreath opportunity to manipulate genes that have a key role in antitumor immune responses. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-12 (IL-12) are two indispensable cytokines for activating dendritic cells and boosting the strong immune responses against cancer. In this review, we describe the antitumor mechanisms and clinical application of gene-modified tumor cells and dendritic cells to secrete GM-CSF or IL-12, respectively, in various preclinical and clinical settings. The principles operative in these vaccination strategies may prove applicable to other immunotherapy strategies, especially in combination with other therapeutic modalities, such as chemotherapy and targeted therapy.

Toward development and production of human T cells in swine for potential use in adoptive T cell immunotherapy

Immunotherapy and vaccination for cancer or infection are generally approached by administration of antigen or stimulation of antigen-presenting cells or both. These measures may fail if the treated individual lacks T cells specific for the immunogen(s). We tested another strategy-the generation of new T cells from hematopoietic stem cells that might be used for adoptive immunotherapy. To test this concept, we introduced T cell-depleted human bone marrow cells into fetal swine and tested the swine for human T cells at various times after birth. Human T cells were detected in the thymus and blood of the treated swine. These cells were generated de novo as they contained human T cell receptor excision circles not present in the T cell-depleted bone marrow. The human T cells were highly diverse and included novel specificities capable of responding to antigen presented by human antigen-presenting cells. Our findings constitute a first step in a new promising approach to immunotherapy in which tumor- or virus-specific T cell clones lacking in an individual might be generated in a surrogate host from hematopoietic stem cells of the individual to be treated.

Separating graft-versus-leukemia from graft-versus-host disease in allogeneic hematopoietic stem cell transplantation

Routine methods to maximize the graft-versus-leukemia (GvL) activity of allogeneic hematopoietic stem cell transplantation (HSCT) without the detrimental effects of graft-versus-host disease (GvHD) are lacking. Depletion or inhibition of alloreactive T cells is partially effective in preventing GvHD, but usually leads to decreased GvL activity. The current model for the pathophysiology of acute GvHD describes a series of immune pathways that lead to activation of donor T cells and inflammatory cytokines responsible for tissue damage in acute GvHD. This model does not account for how allotransplant can lead to GvL effects without GvHD, or how the initial activation of donor immune cells may lead to counter-regulatory effects that limit GvHD. In this review, we will summarize new findings that support a more complex model for the initiation of GvHD and GvL activities in allogeneic HSCT, and discuss the potential of novel strategies to enhance GvL activity of the transplant.

Phase II trial of Belagenpumatucel-L, a TGF-beta2 antisense gene modified allogeneic tumor vaccine in advanced non small cell lung cancer (NSCLC) patients

In a previous dose escalation trial we demonstrated dose related survival correlation to Belagenpumatucel-L. In order to further evaluate safety and response at the previously defined optimal dose and schedule and to gain preliminary evidence on a hypothesis that the level of circulating tumor cells (CTCs) in blood may correlate with the overall survival of patients with stage IV NSCLC, we initiated a phase II trial. Patients received intradermal immunization of 2.5 x 10(7) transfected allogeneic tumor cells (Belagenpumatucel-L, supplied by NovaRx) 1 x every month for a total of 16 months. Circulating tumor cells (Veridex, Raritan, NJ) were measured every 4 weeks. Twenty-one advanced NSCLC patients were enrolled on this study. No significant toxic effect was observed. Overall survival was 562 days. The median survival was 660 days in patients having less than 2 CTCs at baseline compared to 150 days in patients with 2 or more CTCs (P=0.025). Phase II results of safety and response are consistent with prior experience following treatment with Belagenpumatucel-L and there is a suggestion that the number of circulating tumor cells at baseline appears to correlate with overall survival. A larger clinical trial is warranted to further explore this observation.

Role of GM-CSF signaling in cell-based tumor immunization

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent adjuvant in cancer vaccination; however, the specific role of endogenous GM-CSF remains unknown. We performed cell-based vaccination in 2 tumor models. First, we vaccinated C57BL/6 mice lacking either GM-CSF, IL-5, or beta-common chain (betac), a receptor subunit essential for GM-CSF and IL-5 signaling, with melanoma cells engineered to produce GM-CSF. Tumor vaccination was effective in both GM-CSF(-/-) and IL-5(-/-) mice, showing that protective immunization is independent of both endogenous cytokines. However, all betac(-/-) animals developed tumor. Loss of tumor immunity in betac(-/-) mice does not reflect global impairment in cell-mediated immunity, as contact hypersensitivity reaction to haptens is unaltered. The importance of tumor cell-derived GM-CSF was highlighted by recruitment of dendritic cells at the vaccination site in wild-type, GM-CSF(-/-), and IL-5(-/-) but not in betac(-/-) mice. In the second model, vaccination with unmodified RENCA cells showed similar results with efficient immunization in BALB/c wild-type and GM-CSF(-/-), whereas all betac(-/-) animals died. Altogether, our results strongly suggest that although endogenous GM-CSF and IL-5 are not required to induce tumor immunity, signaling through betac receptor is critically needed for efficient cancer vaccination in both genetically modified GM-CSF-secreting tumor cells and a spontaneously immunogenic models.

Anti-programmed death-1 synergizes with granulocyte macrophage colony-stimulating factor--secreting tumor cell immunotherapy providing therapeutic benefit to mice with established tumors

PURPOSE

The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy, which is known to stimulate potent and long-lasting antigen-specific immune responses, in combination with PD-1 blockade, which has been shown to augment cellular immune responses.

EXPERIMENTAL DESIGN

Survival studies were done in the B16 melanoma and CT26 colon carcinoma tumor models. Immune monitoring studies were done in the B16 model. GM-CSF-secreting tumor cell immunotherapy was administered s.c. and the anti-PD-1 antibody was administered i.p.

RESULTS

The studies reported here show that combining PD-1 blockade with GM-CSF-secreting tumor cell immunotherapy prolonged the survival of tumor-bearing animals compared with animals treated with either therapy alone. Prolonged survival correlated with strong antigen-specific T-cell responses detected by tetramer staining and an in vivo CTL assay, higher secretion levels of proinflammatory cytokines by splenocytes, and the persistence of functional CD8+ T cells in the tumor microenvironment. Furthermore, in the biweekly multiple treatment setting, repeated antigen-specific T-cell expansion was only observed following administration of the cellular immunotherapy with the PD-1 blockade and not when the cellular immunotherapy or PD-1 blockade was used as monotherapy.

CONCLUSION

The combination of PD-1 blockade with GM-CSF-secreting tumor cell immunotherapy leads to significantly improved antitumor responses by augmenting the tumor-reactive T-cell responses induced by the cellular immunotherapy. Readministration of the cellular immunotherapy with the anti-PD-1 antibody in subsequent immunotherapy cycles was required to reactivate these T-cell responses.

Enhancing the clinical activity of granulocyte-macrophage colony-stimulating factor-secreting tumor cell vaccines

A comparative analysis of vaccination with irradiated, murine tumor cells engineered to express a large number of immunostimulatory molecules established the superior ability of granulocyte-macrophage colony-stimulating factor (GM-CSF) to evoke potent, specific, and long-lasting anti-tumor immunity. Early stage clinical testing of this vaccination strategy in patients with diverse solid and hematologic malignancies revealed the consistent induction of a coordinated humoral and cellular reaction that effectuated substantial tumor destruction. Nonetheless, most subjects eventually succumbed to progressive disease, implying that additional immune defects remained to be addressed. More detailed investigations of the mechanisms underlying protective immunity in murine systems together with the characterization of the anti-tumor reactions of patients who achieved durable clinical benefits in response to immunotherapy uncovered several pathways that restrain the efficacy of GM-CSF-secreting tumor cell vaccines. These include milk fat globule epidermal growth factor protein-8 expansion of forkhead box protein 3+ regulatory T cells, cytotoxic T-lymphocyte antigen-4-mediated negative costimulation, and soluble major histocompatibility complex class I chain-related protein A suppression of NKG2D-dependent innate and adaptive anti-tumor cytotoxicity. Together, these results define key regulatory circuits that attenuate immune-mediated tumor destruction and suggest novel combinatorial therapies that might enhance the clinical activity of GM-CSF-secreting tumor cell vaccines.

Respiratory Homeostasis and Exploitation of the Immune System for Lung Cancer Vaccines

Lung cancer is the leading cause of all cancer deaths in the US. The international scientific and clinical community has made significant advances toward understanding specific molecular mechanisms underlying lung carcinogenesis; however, despite these insights and advances in surgery and chemoradiotherapy, the prognosis for non-small-cell lung cancer (NSCLC) remains poor. Nonetheless, significant effort is being focused on advancing translational research evaluating the efficacy of novel targeted therapeutic strategies for lung cancer. Illustrative examples of this include antagonists of the epidermal growth factor receptor (EGFR), tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib, and a diverse assortment of anti-angiogenic compounds targeting growth factors and/or their receptors that regulate tumor-associated angiogenic programs. In addition, with the increased awareness of the significant role chronically activated leukocytes play as potentiators of solid-tumor development, the role of innate and adaptive immune cells as regulators of lung carcinogenesis is being examined. While some of these studies are examining how novel therapeutic strategies may enhance the efficacy of lung cancer vaccines, others are evaluating the intrinsic characteristics of the immune response to lung cancer in order to identify rate-limiting molecular and/or cellular programs to target with novel anticancer therapeutics. In this article, we explore important aspects of the immune system and its role in regulating normal respiratory homeostasis compared with the immune response accompanying development of lung cancer. These hallmarks are then discussed in the context of recent efforts to develop lung cancer vaccines, where we have highlighted important concepts that must be taken into consideration for future development of novel therapeutic strategies and clinical trials assessing their efficacy.

Gene immunotherapy for non-small cell lung cancer

Historically, limited results have been observed with immunity in non-small cell lung cancer (NSCLC). In the last 5 years, however, several immune-stimulating products have demonstrated enhancement of tumor antigen recognition through activation of dendritic cell-involved processes. Moreover, clinical benefit has been demonstrated in subsets of patients, justifying ongoing phase III investigation. Results of key gene immunotherapies being tested in NSCLC are reviewed. Preliminary results in advanced NSCLC suggest evidence of well-tolerated immune activation with suggested evidence of clinical benefit with respect to survival and response.

Active specific immunotherapy and cell-transfer therapy for the treatment of non-small cell lung cancer

Lung cancer is an intractable disease urgently requiring more effective treatment approaches. The potential of immunotherapy in this context remains promising, although presently there are no satisfactory protocols available for lung cancer. However, encouraging evidence of clinical benefits from immunotherapy is beginning to accumulate in several lung cancer trials. Better understanding of tumor-specific immune responses, identifying tumor-associated antigens, and manipulating the immunoregulatory environment of the tumor is likely to further increase the efficacy of immune-mediated cancer therapies. Here, we review recent advances in cellular immunotherapy and vaccines for lung cancer, emphasizing an important paradigm shift in the analysis of clinical benefit away from "tumor response" towards "patient response".

Protein disulfide isomerases are antibody targets during immune-mediated tumor destruction

The identification of cancer antigens that contribute to transformation and are linked with immune-mediated tumor destruction is an important goal for immunotherapy. Toward this end, we screened a murine renal cell carcinoma cDNA expression library with sera from mice vaccinated with irradiated tumor cells engineered to secrete granulocyte macrophage colony-stimulating factor (GM-CSF). Multiple nonmutated, overexpressed proteins that function in tumor cell migration, protein/nucleic acid homeostasis, metabolism, and stress responses were detected. Among these, the most frequently recognized clone was protein disulfide isomerase (PDI). High titer antibodies to human PDI were similarly induced in an acute myeloid leukemia patient who achieved a complete response after vaccination with irradiated, autologous GM-CSF-secreting tumor cells in the setting of nonmyeloablative allogeneic bone marrow transplantation. Moreover, ERp5, a closely related disulfide isomerase involved in major histocompatibility complex (MHC) class I chain-related protein A (MICA) shedding, also evoked potent humoral reactions in diverse solid and hematologic malignancy patients who responded to GM-CSF-secreting tumor cell vaccines or antibody blockade of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). Together, these findings reveal the unexpected immunogenicity of PDIs and raise the possibility that these gene products might serve as targets for therapeutic monoclonal antibodies.

Non-transmissible Sendai virus encoding granulocyte macrophage colony-stimulating factor is a novel and potent vector system for producing autologous tumor vaccines

The recent clinical application of granulocyte macrophage colony-stimulating factor (GM-CSF)-transduced autologous tumor vaccines revealed substantial antitumor activity and valuable clinical results. However, for these vaccines to be optimally effective, the antitumor efficacies must be improved. Recently, Sendai virus (SeV) vectors, which are cytoplasmic RNA vectors, have emerged as safe vectors with high gene transduction. In the current study, the in vivo therapeutic antitumor efficacies of irradiated GM-CSF-transduced mouse renal cell carcinoma (RENCA) vaccine cells mediated by either fusion gene-deleted non-transmissible SeV encoding mouse GM-CSF (SeV/dF/G) or adenovirus (E1, E3 deleted serotype 5 adenovirus) encoding mouse GM-CSF (AdV/G) (respectively described as irRC/SeV/GM or irRC/AdV/GM) were compared in RENCA-bearing mice. The results showed that the antitumor effect was equivalent between irRC/SeV/GM and irRC/AdV/GM cells, even though the former produced less GM-CSF in vitro. The cell numbers of activated (CD80(+), CD86(+), CD80( (+) )CD86(+)) dendritic cells in lymph nodes from mice treated with irRC/AdV/GM or irRC/SeV/GM cells were increased significantly compared with those of mice treated with the respective controls, at both the earlier and later phases. In an in vitro cytotoxicity assay, splenocytes harvested from mice treated with both irRC/SeV/GM and irRC/AdV/GM cells showed tumor-specific responses against RENCA cells. The restimulated splenocytes harvested from mice treated with irRC/SeV/GM or irRC/AdV/GM cells produced significantly higher levels of interleukin-2, interleukin-4, and interferon-gamma compared with their respective controls (P < 0.05). Furthermore, vaccination with irRC/AdV/GM or irRC/SeV/GM cells induced significantly enhanced recruitment of the cytolytic effectors of CD107a(+)CD8(+) T cells and CD107a(+) natural killer cells into tumors compared with those induced by their respective controls (P < 0.05). Taken together, our results suggest that the SeV/dF/G vector is a potential candidate for the production of effective autologous GM-CSF-transduced tumor vaccines in clinical cancer immune gene therapy.

Concerted potent humoral immune responses to autoantigens are associated with tumor destruction and favorable clinical outcomes without autoimmunity

PURPOSE

The therapeutic importance of immune responses against single versus multiple antigens is poorly understood. There also remains insufficient understanding whether responses to one subset of antigens are more significant than another. Autoantibodies are frequent in cancer patients. They can pose no biological significance or lead to debilitating paraneoplastic syndromes. Autoreactivity has been associated with clinical benefits, but the magnitude necessary for meaningful results is unknown. Autologous tumor cells engineered to secrete granulocyte macrophage colony-stimulating factor generate immune infiltrates in preexisting metastases with associated tumor destruction. We sought to identify targets of responses from this vaccination strategy.

EXPERIMENTAL DESIGN

Postvaccination sera used in screening a cDNA expression library prepared from a densely infiltrated metastasis of a long-term surviving melanoma patient identified several autoantigens. Additional autoantigens were identified through similar screenings in non-small cell lung cancer and murine models, and proteins implicated in cancer propagation. ELISAs for several targets were established using recombinant proteins, whereas others were evaluated by petit serologies.

RESULTS

Eleven gene products were identified through serologic screening from two patients showing highly favorable clinical outcomes. A subset of antigens revealed significant changes in antibody titers compared with weak responses to other proteins. Time course analyses showed coordinated enhanced titers against several targets as a function of vaccination in responding patients.

CONCLUSIONS

This study shows the range of biologically significant antigens resulting from a whole-cell vaccine. Targets include autoantigens that are components of cell cycle regulation. Potent antibody responses against multiple autoantigens are associated with effective tumor destruction without clinical autoimmunity.

TARC and RANTES enhance antitumor immunity induced by the GM-CSF-transduced tumor vaccine in a mouse tumor model

INTRODUCTION

Transduction of the granulocyte-macrophage colony stimulating factor (GM-CSF) gene into mouse tumor cells abrogates their tumorigenicity in vivo. Our previous report demonstrated that gene transduction of GM-CSF with either TARC or RANTES chemokines suppressed in vivo tumor formation. In this paper, we examined whether the addition of either recombinant TARC or RANTES proteins to irradiated GM-CSF-transduced tumor vaccine cells enhanced antitumor immunity against established mouse tumor models to examine its future clinical application.

MATERIALS AND METHODS

Three million irradiated WEHI3B cells retrovirally transduced with murine GM-CSF cDNA in combination with either recombinant TARC or RANTES were subcutaneously inoculated into syngeneic WEHI3B-preestablished BALB/c mice.

RESULTS

Vaccinations were well tolerated. Mice treated with GM-CSF-transduced cells and the chemokines demonstrated significantly longer survival than mice treated with GM-CSF-transduced cells alone. Splenocytes harvested from mice treated with the former vaccines produced higher levels of IL-4, IL-6, IFN-gamma, and TNF-alpha, suggesting enhanced innate and adaptive immunity. Immunohistochemical analysis of tumor sections after vaccination revealed a more significant contribution of CD4+ and CD8+ T cells to tumor repression in the combined vaccine groups than controls.

CONCLUSIONS

TARC and RANTES enhance the immunological antitumor effect induced by GM-CSF in mouse WEHI3B tumor models and may be clinically useful.

Harnessing the immune system for ovarian cancer therapy

The clinical course of ovarian cancer is often marked by periods of relapse and remission until chemo-resistance develops. Patients in remission with minimal disease burdens are ideally suited for the evaluation of immune-based strategies. Major obstacles to the development of successful immune strategies include the identification of tumor-restricted immunogenic targets, generation of a sufficient immune response to cause tumor rejection, and approaches to overcome evasion of immune attack. Many questions remain as optimal strategies are developed, which include: (i) What is the best antigen form (e.g. peptides, proteins or tumor lysates)? (ii) What are the appropriate adjuvants? (iii) Are mono-valent or multi-valent vaccines likely to be more effective? (iv) What is the optimal frequency and duration of vaccination? (v) How should antigen-specific responses be monitored? and (vi) How should the anti-cancer response be maintained? In this review, we explore representative examples of immune strategies under investigation for patients with ovarian carcinoma which illustrate many of these issues. Basic principles generic to all these immunotherapeutic approaches will also be discussed.

Big tumor regression induced by GM-CSF gene-modified 3LL tumor cells via facilitating DC maturation and deviation toward CD11c+CD8alpha+ subset

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a powerful immune-stimulating factor that helps to generate a systemic, strong, and long-lasting immune response. However, whether the transduction of GM-CSF to tumor cell results in tumor regression and optimizes local immune microenvironment remains to be investigated. In this study, using an experimental murine tumor model, we demonstrated that the in vivo growth of 3LL tumor cells modified with the GM-CSF gene (3LL-GM) was inhibited even when the tumor diameter was over 7 mm (big tumor), and mice inoculated with GM-CSF gene-modified 3LL cells survived over 90 days, whereas mice inoculated with control parental 3LL cells and 3LL cells transduced with control vector all succumbed to the tumor by day 17 after tumor inoculation. Further analysis showed that targeted expression of GM-CSF in 3LL tumor cells markedly enhanced the systemic antitumor effect, including specific lymphocytes proliferation, cytotoxicity against 3LL tumor, and increased production of IFN-gamma. GM-CSF gene-modified 3LL cells significantly protected the mice from the parental 3LL tumor challenge. More importantly, the percentage of dendritic cells (DCs) in tumor site was greatly increased and the DCs differentiated into CD11c(+)CD8alpha(+) cells, which were reported to be able to benefit the induction of CD8(+) cytotoxic T lymphocytes (CTLs) that contribute to tumor regression. Our research indicated that GM-CSF could optimize the immune microenvironment in the tumor site, which provides a potent approach for immunotherapy of tumors.

Immune modulation as a therapeutic strategy for non-small-cell lung cancer

Active tumor immunotherapy may provide hope for patients with non-small-cell lung cancer (NSCLC) because, in more than 20 years, current therapies have yet to change mortality statistics. Creating an efficacious vaccine involves selection of important tumor antigens and formulation of their immunogenic epitopes into a construct for delivery to antigen-presenting cells. The method of immunization will confer significant properties to the potency of the vaccine and might require augmentation with certain adjuvant agents like interleukin-12 and granulocyte-macrophage colony-stimulating factor. So far, clinical trials in NSCLC immunotherapy have shown promise with the Induction of Immune responses and the presence of clinical responses compared with historical controls treated with standard therapy. Immunotherapy could merge seamlessly into the current standard of care for NSCLC with the emergence of data supporting a beneficial role of chemotherapy and radiation in the production of antitumor immune responses. With continued work in this field, active immunotherapy may provide the necessary therapy for the successful treatment of this common disease.

Cell based cancer vaccines: regulatory and commercial development

There is both clinical and regulatory drive to expedite development of safe, efficacious cancer therapies. Stimulation of the patients immune system through vaccination with tumour cells has long been at the vanguard of cancer therapeutic vaccines, and several have been demonstrated to be safe and to have efficacy in early clinical trials for a range of cancers including melanoma, renal cell carcinoma, prostate and colorectal cancers. A number of development-stage vaccines and strategies are currently being tested, utilising either autologous or allogeneic tumour cells, which may also have been ex vivo manipulated (e.g. cytokine transfected cells). It seems likely that clinical trial success, and hence patient benefit, could be improved through better patient identification, possibly by the discovery and use of novel immune response biomarkers. In this review, we aim to summarise the state of tumour cell vaccines in commercial development and to explore not only the difficulties of determining efficacy, but also the production challenges faced when developing a vaccine from proof of principle to pivotal phase III trials.

Phase I/II trial of an allogeneic cellular immunotherapy in hormone-naïve prostate cancer

PURPOSE

To determine the toxicity, immunologic, and clinical activity of immunotherapy with irradiated, allogeneic, prostate cancer cells expressing granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with recurrent prostate cancer.

PATIENTS AND METHODS

A single-institution phase I/II trial was done in hormone therapy-naïve patients with prostate-specific antigen (PSA) relapse following radical prostatectomy and absence of radiologic metastases. Treatments were administered weekly via intradermal injections of 1.2 x 10(8) GM-CSF gene-transduced, irradiated, cancer cells (6 x 10(7) LNCaP cells and 6 x 10(7) PC-3 cells) for 8 weeks.

RESULTS

Twenty-one patients were enrolled and treated. Toxicities included local injection-site reactions, pruritus, and flu-like symptoms. One patient had a partial PSA response of 7-month duration. At 20 weeks post first treatment, 16 of 21 (76%) patients showed a statistically significant decrease in PSA velocity (slope) compared with prevaccination (P < 0.001). Injection site biopsies showed intradermal infiltrates consisting of CD1a+ dendritic cells and CD68+ macrophages, similar to previous clinical trials using autologous GM-CSF-transduced cancer cells. Posttreatment, patients developed new oligoclonal antibodies reactive against at least five identified antigens present in LNCaP or PC-3 cells. A high-titer antibody response against a 250-kDa antigen expressed on normal prostate epithelial cells was induced in a patient with partial PSA remission; titers of this antibody decreased when treatment ended, and subsequent PSA relapse occurred.

CONCLUSIONS

This non-patient-specific prostate cancer immunotherapy has a favorable safety profile and is immunologically active. Continued clinical investigation at higher doses and with longer boosting schedules is warranted.

Vaccine therapy in non-small-cell lung cancer

Lung cancer is the leading cause of death from cancer worldwide. First-line therapy is based on stage at diagnosis and can include chemotherapy, radiation, and surgery. Despite advances, the prognosis for advanced-stage lung cancer is very poor. Vaccines with the capability to activate the host immune system may have a role in second-line therapy. Advances in the understanding of cellular and molecular immunology are forming the basis for improving vaccine therapy. Most trials to date have demonstrated safety but inconsistent efficacy. Further research is needed to enhance this potential.

Localized hyperthermia combined with intratumoral dendritic cells induces systemic antitumor immunity

Prostate adenocarcinoma, treated with localized tumor hyperthermia (LTH), can potentially serve as a source of tumor antigen, where dying apoptotic/necrotic cells release tumor peptides slowly over time. In addition, LTH-treated cells can release heat shock proteins that can chaperone antigenic peptides to antigen-presenting cells, such as dendritic cells. We attempted to discern whether sequential LTH and intratumoral dendritic cell and/or systemic granulocyte macrophage colony-stimulating factor (GM-CSF) would activate antitumor immune response in a syngeneic murine model of prostate cancer (RM-1). Palpable RM-1 tumors, grown in the distal appendage of C57BL/6 male mice, were subjected to LTH (43.7 degrees C for 1 h) x 2, separated by 5 days. Following the second LTH treatment, animals received either PBS or dendritic cells (2 x 10(6)) intratumorally (every 3 days for three injections). Separate cohorts also received i.v. injection of recombinant adenovirus-expressing murine GM-CSF (AdGMCSF), 1 day after LTH. Control animals received AdenoLacZ or AdenoGFP. Intratumoral dendritic cell injection induced tumor-specific T-helper cell activity (IFNgamma ELISPOTS) and CTL activity, which was further augmented by AdGMCSF, indicating amplification of tumor-specific TH1 immunity. The combination of LTH, AdGMCSF, and intratumoral dendritic cell injection resulted in significant tumor growth delays when compared with animal cohorts that received LTH alone. These results support an in situ autovaccination strategy where systemic administration of GM-CSF and/or intratumoral injection of autologous dendritic cells, when combined with LTH, could be an effective treatment for local and systemic recurrence of prostate cancer.

Established B16 tumors are rejected following treatment with GM-CSF-secreting tumor cell immunotherapy in combination with anti-4-1BB mAb

Immunization with irradiated tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates potent, specific and long lasting anti-tumor immunity in clinical and preclinical settings. Efforts to further increase immunotherapy efficacy with immune-modulatory agents are under evaluation. Based on the immune-modulatory properties of 4-1BB (CD137), it has been postulated that agonistic 4-1BB antibodies may add additional anti-tumor efficacy to GM-CSF-secreting tumor cell immunotherapy. The combination of GM-CSF-secreting tumor cell immunotherapy and anti-4-1BB monoclonal antibody (mAb) treatment resulted in rejection of established tumors in the B16 melanoma model. These anti-tumor effects correlated with persistent tumor-specific CD8(+) T cell responses. In addition, early tumor infiltration of functional CD8(+) T cells and a greater expansion of antigen-specific memory T cells were found in mice treated with the combination therapy. In summary, an agonistic anti-4-1BB mAb combined with GM-CSF-secreting tumor cell immunotherapy may provide a novel and potent treatment strategy for patients with cancer.

GM-CSF-secreting cancer immunotherapies: preclinical analysis of the mechanism of action

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapies have demonstrated long-lasting, and specific anti-tumor immune responses in animal models. The studies reported here specifically evaluate two aspects of the immune response generated by such immunotherapies: the persistence of irradiated tumor cells at the immunization site, and the breadth of the immune response elicited to tumor associated antigens (TAA) derived from the immunotherapy. To further define the mechanism of GM-CSF-secreting cancer immunotherapies, immunohistochemistry studies were performed using the B16F10 melanoma tumor model. In contrast to previous reports, our data revealed that the irradiated tumor cells persisted and secreted high levels of GM-CSF at the injection site for more than 21 days. Furthermore, dense infiltrates of dendritic cells were observed only in mice treated with GM-CSF-secreting B16F10 cells, and not in mice treated with unmodified B16F10 cells with or without concurrent injection of rGM-CSF. In addition, histological studies also revealed enhanced neutrophil and CD4+ T cell infiltration, as well as the presence of apoptotic cells, at the injection site of mice treated with GM-CSF-secreting tumor cells. To evaluate the scope of the immune response generated by GM-CSF-secreting cancer immunotherapies, several related B16 melanoma tumor cell subclones that exist as a result of genetic drift in the original cell line were used to challenge mice previously immunized with GM-CSF-secreting B16F10 cells. These studies revealed that GM-CSF-secreting cancer immunotherapies elicit T cell responses that effectively control growth of related but antigenically distinct tumors. Taken together, these studies provide important new insights into the mechanism of action of this promising novel cancer immunotherapy.

Adjuvant therapeutic vaccination in patients with non-small cell lung cancer made lymphopenic and reconstituted with autologous PBMC: first clinical experience and evidence of an immune response

Background

Given the considerable toxicity and modest benefit of adjuvant chemotherapy for non-small cell lung cancer (NSCLC), there is clearly a need for new treatment modalities in the adjuvant setting. Active specific immunotherapy may represent such an option. However, clinical responses have been rare so far. Manipulating the host by inducing lymphopenia before vaccination resulted in a magnification of the immune response in the preclinical setting. To evaluate feasibility and safety of an irradiated, autologous tumor cell vaccine given following induction of lymphopenia by chemotherapy and reinfusion of autologous peripheral blood mononuclear cells (PBMC), we are currently conducting a pilot-phase I clinical trial in patients with NSCLC following surgical resection. This paper reports on the first clinical experience and evidence of an immune response in patients suffering from NSCLC.

Methods

NSCLC patients stages I-IIIA are recruited. Vaccines are generated from their resected lung specimens. Patients undergo leukapheresis to harvest their PBMC prior to or following the surgical procedure. Furthermore, patients receive preparative chemotherapy (cyclophosphamide 350 mg/m² and fludarabine 20 mg/m² on 3 consecutive days) for induction of lymphopenia followed by reconstitution with their autologous PBMC. Vaccines are administered intradermally on day 1 following reconstitution and every two weeks for a total of up to five vaccinations. Granulocyte-macrophage-colony-stimulating-factor (GM-CSF) is given continuously (at a rate of 50 μg/24 h) at the site of vaccination via minipump for six consecutive days after each vaccination.

Results

To date, vaccines were successfully manufactured for 4 of 4 patients. The most common toxicities were local injection-site reactions and mild constitutional symptoms. Immune responses to chemotherapy, reconstitution and vaccination are measured by vaccine site and delayed type hypersensitivity (DTH) skin reactions. One patient developed positive DTH skin tests so far. Immunohistochemical assessment of punch biopsies taken at the local vaccine site reaction revealed a dense lymphocyte infiltrate. Further immunohistochemical differentiation showed that CD1a+ cells had been attracted to the vaccine site as well as predominantly CD4+ lymphocytes. The 3-day combination chemotherapy consisting of cyclophosphamide and fludarabine induced a profound lymphopenia in all patients. Sequential FACS analysis revealed that different T cell subsets (CD4, CD8, CD4CD25) as well as granulocytes, B cells and NK cells were significantly reduced. Here, we report on clinical safety and feasibility of this vaccination approach during lymphoid recovery and demonstrate a patient example.

Conclusion

Thus far, all vaccines were well tolerated. The overall trial design seems safe and feasible. Vaccine site reactions associated with infusion of GM-CSF via mini-pump are consistent with the postulated mechanism of action. More detailed immune-monitoring is required to evaluate a potential systemic immune response. Further studies to exploit homeostasis-driven T cell proliferation for the induction of a specific anti-tumor immune response in this clinical setting are warranted.

Immunologic approaches to ovarian cancer treatment

The clinical course of ovarian cancer is often marked by periods of relapse and remission until chemotherapy resistance develops. Patients in remission with minimal disease burdens are ideally suited for the evaluation of immune-based strategies. The role of immune surveillance in improving outcome has been supported by the correlation of increased survival with the presence or absence of tumor-infiltrating lymphocytes in a given patient. Major obstacles to the development of successful immune strategies include the identification of tumor-restricted immunogenic targets, generation of a sufficient immune response to cause tumor rejection, and approaches to overcome evasion of immune attack. As optimal strategies are being developed, many questions remain. Some of the questions are as follows: What is the best antigen form (eg, peptides, proteins, or tumor lysates)? What are the appropriate adjuvants? Are monovalent or multivalent vaccines likely to be more effective? What is the optimal frequency and duration of vaccination? How should antigen-specific responses be monitored? How should the anticancer response be maintained? In this review, we will explore representative examples of immune strategies under investigation for patients with ovarian carcinoma that illustrate many of these issues. We will review ongoing phase III studies for patients in first clinical remission. Basic principles generic to all these immunotherapeutic approaches will be discussed in the hopes of yielding the most promising results as the field continues to evolve.

Vaccination of patients with advanced non-small-cell lung cancer with an optimized cryptic human telomerase reverse transcriptase peptide

PURPOSE

To evaluate the immunological and clinical response as well as the safety of the optimized peptide telomerase reverse transcriptase p572Y (TERT572Y) presented by HLA-A*0201 in patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Twenty-two patients with advanced NSCLC and residual (n = 8) or progressive disease (PD; n = 14) following chemotherapy and/or radiotherapy received two subcutaneous injections of the optimized TERT572Y peptide followed by four injections of the native TERT572 peptide administered every 3 weeks. Peptide-specific immune responses were monitored by enzyme-linked immunosorbent spot assay and/or TERT572Y pentamer staining.

RESULTS

Twelve (54.5%) of 22 patients completed the vaccination program. Toxicity consisted primarily of local skin reactions. TERT572-specific CD8+ cells were detected in 16 (76.2%) of 21 patients after the second vaccination, and 10 (90.9%) of 11 patients after the sixth vaccination. Stable disease (SD) occurred in eight (36.4%) of 22 vaccinated patients, with three (13.6%) having had PD before entering the study. The median duration of SD was 11.2 months. After a median follow-up of 10.0 months, patients with early developed immunological response (n = 16) had a significantly longer time to progression and overall survival (OS) than nonresponders (n = 5; log-rank tests P = .046 and P = .012, respectively). The estimated median OS was 30.0 months (range, 2.8 to 40.0 months) and 4.1 months (range, 2.4 to 10.9 months) for responders and nonresponders, respectively.

CONCLUSION

TERT572Y peptide vaccine is well tolerated and effective in eliciting a specific T cell immunity. Immunological response is associated with prolonged survival. These results are encouraging and warrant further evaluation in a randomized study.

Nonspecific immunotherapy with intratumoral lipopolysaccharide and zymosan A but not GM-CSF leads to an effective anti-tumor response in subcutaneous RG-2 gliomas

PURPOSE

Nonspecific stimulation of cells of the immune system may be useful in generating an anti-tumor response for a variety of cancers and may work synergistically with currently available cytotoxic therapies. In this study we examined the response of syngeneic rat gliomas to treatment with several nonspecific stimulators of dendritic cells and macrophages alone or in combination with radiation therapy.

EXPERIMENTAL DESIGN

RG-2 gliomas were implanted subcutaneously and treated with intratumoral (IT) injections of the toll-like receptor (TLR) ligands lipopolysaccharide (LPS) and zymosan A (ZymA) and the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF). Combination treatment with IT LPS and single-fraction external beam radiotherapy (EBRT) was also evaluated.

RESULTS

Treatment with IT LPS and ZymA delayed tumor growth compared to saline controls. Multiple doses of both substances were superior to single doses, and led to complete tumor regression in 71% (LPS) and 50% (ZymA) of animals. GM-CSF showed no anti-tumor effects in this study. Combinations of IT LPS and EBRT appeared to have a synergistic effect in delaying tumor growth. Rechallenge studies and IT LPS treatment of RG-2 tumors in nude rats suggested the importance of T cells in this treatment paradigm.

CONCLUSIONS

Direct IT treatment with the TLR ligands LPS and ZymA are effective in generating an anti-tumor response. These treatments may synergize with cytotoxic therapies such as EBRT, and appear to require T cells for a successful outcome.

Recombinant IL-7 enhances the potency of GM-CSF-secreting tumor cell immunotherapy

IL-7 is known for its role in lymphopoiesis and T-cell homeostasis. In addition, its capacity to augment the immune response to weak or low affinity antigens makes it an ideal candidate to evaluate in combination with a GM-CSF-secreting tumor cell immunotherapy, which has been shown to elicit broad humoral and cellular immune responses. The studies reported here show that IL-7, when combined with a GM-CSF-secreting tumor cell immunotherapy, significantly prolonged the survival of tumor-bearing mice. The enhanced anti-tumor protection correlated with an increased number of activated dendritic cells (DC) and T cells in lymphoid tissues, such as the draining lymph nodes (DLN) and spleen. Moreover, an increased number of activated effector T cells were found in the tumor microenvironment, correlating with a more potent systemic tumor-specific T-cell response than each monotherapy alone. Taken together, these studies demonstrate that IL-7 augments the anti-tumor response of a GM-CSF-secreting tumor cell immunotherapy in preclinical models.

Cytokine gene transfer for cancer therapy

The possibility of inducing a strong immune response to impair tumor growth by ectopically expressing cytokines, followed by the generation of an antitumor memory raised great hopes and enthusiasm as a therapeutic approach. However, the efficacy of this strategy on established tumor models appeared low and the initial results in the clinics were disappointing. Recently, new evidence indicates that cytokine gene combination or the combined use of cytokine genes with additional gene therapy approaches induces a synergistic effect supporting the use of cytokine gene therapy to improve the clinical outcome for cancer patients.

Vascular endothelial growth factor blockade reduces intratumoral regulatory T cells and enhances the efficacy of a GM-CSF-secreting cancer immunotherapy

PURPOSE

The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy in combination with vascular endothelial growth factor (VEGF) blockage in preclinical models.

EXPERIMENTAL DESIGN

Survival and immune response were monitored in the B16 melanoma and the CT26 colon carcinoma models. VEGF blockade was achieved by using a recombinant adeno-associated virus vector expressing a soluble VEGF receptor consisting of selected domains of the VEGF receptors 1 and 2 (termed sVEGFR1/R2). Dendritic cell and tumor infiltrating lymphocyte activation status and numbers were evaluated by fluorescence-activated cell sorting analysis. Regulatory T cells were quantified by their CD4+CD25hi and CD4+FoxP3+ phenotype.

RESULTS

The present study established that GM-CSF-secreting tumor cell immunotherapy with VEGF blockade significantly prolonged the survival of tumor-bearing mice. Enhanced anti-tumor protection correlated with an increased number of activated CD4+ and CD8+ tumor-infiltrating T cells and a pronounced decrease in the number of suppressive regulatory T cells residing in the tumor. Conversely, overexpression of VEGF from tumors resulted in elevated numbers of regulatory T cells in the tumor, suggesting a novel mechanism of VEGF-mediated immune suppression at the tumor site.

CONCLUSION

GM-CSF-secreting cancer immunotherapy and VEGF blockade increases the i.t. ratio of effector to regulatory T cells to provide enhanced antitumor responses. This therapeutic combination may prove to be an effective strategy for the treatment of patients with cancer.

Adenovirus vaccination against neu oncogene exerts long-term protection from tumorigenesis in BALB/neuT transgenic mice

The transforming rat HER2/neu oncogene (neu), when embedded in the genome of transgenic BALB/c (neuT) mice, provokes the development of an invasive carcinoma in each of their 10 mammary glands. We used the neuT mice model system to evaluate the immunization efficiency and the protective effect of intramuscular injection of adenovirus (Ad) and/or of DNA with electrostimulation (DNA+ES), both expressing the rat p185(neu) protein. A neu cDNA sequence, which exclusively contains codons preferred by highly expressed mammalian genes, was used in this study. This "optimized" cDNA displayed higher expression in cultured cells and greater cell-mediated response than the original gene when injected as DNA+ES. Ad expressing the optimized sequence (Ad5-neu.opt) induced a higher immune response, as measured by the frequency of IFN-gamma-secreting spleen cells and antibody titers. Different Ad/DNA combinations and immunization schedules confirmed the superiority of Ad5-neu.opt in inducing a strong Th1-skewed humoral and CD8(+) cell-mediated response. Two Ad5-neu.opt injections of 10(9) viral particles at week 10 and 12 were sufficient to induce the highest response, which persisted at detectable levels up to 33 weeks of age. Anti-Ad5 antibodies elicited by previous injections neutralized the effect of an additional Ad5-neu.opt immunization at week 19. A group, which received 3 injections of DNA+ES at week 23, 27 and 31, in addition to the 3 Ad injections at week 10, 12 and 19 showed an increased frequency of IFN-gamma(+), CD8(+) PBMC at week 25, which persisted at detectable levels till week 38. Ad5-neu.opt administration at 10 and 12 weeks of age had a significant impact on tumor progression. At 44 weeks, 40% of the mice were completely protected from tumors with a mean tumor of 3.8. In contrast, control mice developed 10 tumors and died by week 27. Vaccination blocked the tumor development at the atypical hyperplasia stage present at the time of treatment. Tumors developing at later times express reduced levels of rat p185(neu) protein.

A review of vaccine clinical trials for non-small cell lung cancer

Recent evidence suggests that vaccines which enhance tumour antigen recognition may provide clinical benefit to subsets of non-small cell lung cancer patients. In this review, a variety of peptide-, gene- and cell-based clinical vaccine approaches targeting non-small cell lung cancer patients are reviewed. Results consistently demonstrate lack of toxicity. Examples of prolonged stable disease, tumour shrinkage response and survival benefit in comparison with historical and low-dose control groups have been demonstrated. Specific vaccines fulfilling justification for Phase III evaluation based on these results include LBLP25, TGF-beta2 antisense gene vaccine and GVAX.

The role of CD4+ T cell help in cancer immunity and the formulation of novel cancer vaccines

Recent years have seen the unprecedented surge of interest in the role of CD4+ T cells and the role they play in the development of the immune response. In this symposium review, we examine the evidence for this and discuss their functions, particularly in respect to the cancer immunology, including CD4+CD25+ cells (Treg).

Tumor Cell Vaccines

This chapter reviews the history of tumor cell vaccines, both autologous and allogeneic, as well as adjuvants used with tumor cell vaccines. The chapter discusses various tumor cell modifications that have been tested over the years. The immune response to tumor vaccines is briefly described, as are some methods of immune monitoring after vaccine therapy. Finally, there is a description of various tumor cell-based vaccines that have been tested in clinical trials.