Granulocyte-macrophage-colony-stimulating factor added to a multipeptide vaccine for resected Stage II melanoma

Co-formulation of the rF1V plague vaccine with depot-formulated cytokines enhances immunogenicity and efficacy to elicit protective responses against aerosol challenge in mice

This study evaluated a depot-formulated cytokine-based adjuvant to improve the efficacy of the recombinant F1V (rF1V) plague vaccine and examined the protective response following aerosol challenge in a murine model. The results of this study showed that co-formulation of the Alhydrogel-adsorbed rF1V plague fusion vaccine with the depot-formulated cytokines recombinant human interleukin 2 (rhuIL-2) and/or recombinant murine granulocyte macrophage colony-stimulating factor (rmGM-CSF) significantly enhances immunogenicity and significant protection at lower antigen doses against a lethal aerosol challenge. These results provide additional support for the co-application of the depot-formulated IL-2 and/or GM-CSF cytokines to enhance vaccine efficacy.

Breast Cancer Vaccines: Disappointing or Promising?

Breast cancer has become the most commonly diagnosed cancer globally. The relapse and metastasis of breast cancer remain a great challenge despite advances in chemotherapy, endocrine therapy, and HER2 targeted therapy in the past decades. Innovative therapeutic strategies are still critically in need. Cancer vaccine is an attractive option as it aims to induce a durable immunologic response to eradicate tumor cells. Different types of breast cancer vaccines have been evaluated in clinical trials, but none has led to significant benefits. Despite the disappointing results at present, new promise from the latest study indicates the possibility of applying vaccines in combination with anti-HER2 monoclonal antibodies or immune checkpoint blockade. This review summarizes the principles and mechanisms underlying breast cancer vaccines, recapitulates the type and administration routes of vaccine, reviews the current results of relevant clinical trials, and addresses the potential reasons for the setbacks and future directions to explore.

Engineering extracellular vesicles for cancer therapy: recent advances and challenges in clinical translation

Extracellular vesicles (EVs) are receiving increasing attention in recent years in the field of cancer treatment. EVs contain specific contents closely related to their donor cells, such as miRNAs, proteins and dsDNAs. As endogenous vesicles, EVs naturally have the characteristics of low toxicity and low immunogenicity and can stably pass through the circulatory system to reach the recipient cells, which make them good carriers to deliver therapeutic agents such as nucleic acid sequences and chemotherapeutics. In many preclinical studies and clinical trials, EVs have demonstrated their unlimited advantages in the field of cancer therapy. However, there are still some challenges that restrict their clinical application, such as yield, heterogeneity, safety, and specificity. In this review, we will focus on the latest breakthrough of EVs in the field of cancer treatment and discuss the challenges in the clinical translation of EVs.

Cancer Vaccines: Adjuvant Potency, Importance of Age, Lifestyle, and Treatments

Although the discovery and characterization of multiple tumor antigens have sparked the development of many antigen/derived cancer vaccines, many are poorly immunogenic and thus, lack clinical efficacy. Adjuvants are therefore incorporated into vaccine formulations to trigger strong and long-lasting immune responses. Adjuvants have generally been classified into two categories: those that ‘depot’ antigens (e.g. mineral salts such as aluminum hydroxide, emulsions, liposomes) and those that act as immunostimulants (Toll Like Receptor agonists, saponins, cytokines). In addition, several novel technologies using vector-based delivery of antigens have been used. Unfortunately, the immune system declines with age, a phenomenon known as immunosenescence, and this is characterized by functional changes in both innate and adaptive cellular immunity systems as well as in lymph node architecture. While many of the immune functions decline over time, others paradoxically increase. Indeed, aging is known to be associated with a low level of chronic inflammation—inflamm-aging. Given that the median age of cancer diagnosis is 66 years and that immunotherapeutic interventions such as cancer vaccines are currently given in combination with or after other forms of treatments which themselves have immune-modulating potential such as surgery, chemotherapy and radiotherapy, the choice of adjuvants requires careful consideration in order to achieve the maximum immune response in a compromised environment. In addition, more clinical trials need to be performed to carefully assess how less conventional form of immune adjuvants, such as exercise, diet and psychological care which have all be shown to influence immune responses can be incorporated to improve the efficacy of cancer vaccines. In this review, adjuvants will be discussed with respect to the above-mentioned important elements.

Empirical and Rational Design of T Cell Receptor-Based Immunotherapies

The use of T cells reactive with intracellular tumor-associated or tumor-specific antigens has been a promising strategy for cancer immunotherapies in the past three decades, but the approach has been constrained by a limited understanding of the T cell receptor’s (TCR) complex functions and specificities. Newer TCR and T cell-based approaches are in development, including engineered adoptive T cells with enhanced TCR affinities, TCR mimic antibodies, and T cell-redirecting bispecific agents. These new therapeutic modalities are exciting opportunities by which TCR recognition can be further exploited for therapeutic benefit. In this review we summarize the development of TCR-based therapeutic strategies and focus on balancing efficacy and potency versus specificity, and hence, possible toxicity, of these powerful therapeutic modalities.

An update on GM-CSF and its potential role in melanoma management

GM-CSF drives the differentiation of granulocytes and monocyte/macrophages from hematopoietic stem cell progenitors. It is required for differentiating monocytes into dendritic cells (DC). Although approved for recovery of granulocytes/monocytes in patients receiving chemotherapy, G-CSF is preferred. Enthusiasm for GM-CSF monotherapy as a melanoma treatment was dampened by two large randomized trials. Although GM-CSF has been injected into tumors for many years, the efficacy of this has not been tested. There is a strong rationale for GM-CSF as a vaccine adjuvant, but it appears of benefit only for strategies that directly involve DCs, such as intratumor talimogene laherparepvec and vaccines in which DCs are loaded with antigen ex vivo and injected admixed with GM-CSF.

Advances in therapeutic applications of extracellular vesicles

Extracellular vesicles (EVs) are nanometer-sized, lipid membrane-enclosed vesicles secreted by most, if not all, cells and contain lipids, proteins, and various nucleic acid species of the source cell. EVs act as important mediators of intercellular communication that influence both physiological and pathological conditions. Given their ability to transfer bioactive components and surmount biological barriers, EVs are increasingly being explored as potential therapeutic agents. EVs can potentiate tissue regeneration, participate in immune modulation, and function as potential alternatives to stem cell therapy, and bioengineered EVs can act as delivery vehicles for therapeutic agents. Here, we cover recent approaches and advances of EV-based therapies.

Personalized cancer vaccines: adjuvants are important, too

Therapeutic cancer vaccines have shown limited clinical efficacy so far. Nevertheless, in the meantime, our understanding of immune cell function and the interactions of immune cells with growing tumors has advanced considerably. We are now in a position to invest this knowledge into the design of more powerful vaccines and therapy combinations aimed at increasing immunogenicity and decreasing tumor-induced immunosuppression. This review focuses essentially on peptide-based human vaccines. We will discuss two aspects that are critical for increasing their intrinsic immunogenicity: the selection of the antigen(s) to be targeted, and the as yet unmet need for strong adjuvants.

Rational combinations of in vivo cancer antigen priming and adoptive T-cell therapy mobilize immune and clinical responses in terminal cancers

PURPOSE

It is now recognized that solid tumors encroach on the host's immune microenvironment to favor its own proliferation. Strategies to enhance the specificity of the endogenous T-cell population against tumors have been met with limited clinical success. We aimed to devise a two-tier protocol coupling in vivo whole antigen priming with ex vivo cellular expansion to clinically evaluate survival in patients following re-infusion of primed, autologous T cells, thereby determining treatment efficacy.

EXPERIMENTAL DESIGN

Treatment commenced with the acquisition of whole tumor antigens from tumor cell lines corresponding with patients' primary malignancy. Lysate mixture was inoculated intradermally, while peripheral blood mononuclear cells (PBMCs) were periodically extracted via phlebotomy and expanded in culture ex vivo for re-infusion. Post-treatment tumor-specific T-cell response and cytotoxicity was confirmed via Elispot and real-time cell analyzing (RTCA) assay. Serum cytokine levels and cytotoxicity scores were evaluated for associations with survival status and duration.

RESULTS

There was a significant increase in cytotoxicity exhibited by T cells measured using both Elispot and RTCA following treatment. Correlation analysis determined significant association between higher post-treatment cytotoxicity scores and survival status (R = 0.52, p = 0.0028) as well as longer survival duration in months (R = 0.59, p = 0.005).

CONCLUSIONS

Our treatment protocol successfully demonstrated significant correlation between tumor-associated antigen-specific immune response and objective prolongation of survival. Whole-cell cancer antigen priming and adoptive T-cell therapy is, therefore, a highly feasible clinical model which can be easily replicated to positively influence outcome in end-stage malignancy.

Trial Watch: Immunostimulation with recombinant cytokines for cancer therapy

Cytokines regulate virtually aspects of innate and adaptive immunity, including the initiation, execution and extinction of tumor-targeting immune responses. Over the past three decades, the possibility of using recombinant cytokines as a means to elicit or boost clinically relevant anticancer immune responses has attracted considerable attention. However, only three cytokines have been approved so far by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, namely, recombinant interleukin (IL)-2 and two variants of recombinant interferon alpha 2 (IFN-α2a and IFN-α2b). Moreover, the use of these cytokines in the clinics is steadily decreasing, mostly as a consequence of: (1) the elevated pleiotropism of IL-2, IFN-α2a and IFN-α2b, resulting in multiple unwarranted effects; and (2) the development of highly effective immunostimulatory therapeutics, such as immune checkpoint blockers. Despite this and other obstacles, research in the field continues as alternative cytokines with restricted effects on specific cell populations are being evaluated. Here, we summarize research preclinical and clinical developments on the use of recombinant cytokines for immunostimulation in cancer patients.

Development of Peptide Vaccines in Dengue

Dengue is one of the most important arboviral infections worldwide, infecting up to 390 million people and causing 25,000 deaths annually. Although a licensed dengue vaccine is available, it is not efficacious against dengue serotypes that infect people living in South East Asia, where dengue is an endemic disease. Hence, there is an urgent need to develop an efficient dengue vaccine for this region. Data from different clinical trials indicate that a successful dengue vaccine must elicit both neutralizing antibodies and cell mediated immunity. This can be achieved by designing a multi-epitope peptide vaccine comprising B, CD8+ and CD4+ T cell epitopes. As recognition of T cell epitopes are restricted by human leukocyte antigens (HLA), T cell epitopes which are able to recognize several major HLAs will be preferentially included in the vaccine design. While peptide vaccines are safe, biocompatible and cost-effective, it is poorly immunogenic. Strategies to improve its immunogenicity by the use of long peptides, adjuvants and nanoparticle delivery mechanisms are discussed.

Microneedle-Assisted, DC-Targeted Codelivery of pTRP-2 and Adjuvant of Paclitaxel for Transcutaneous Immunotherapy

This work aims at developing an immunotherapeutic strategy to deliver a cancer DNA vaccine targeting dendritic cells (DCs), to trigger their maturation and antitumor function, and reduce immune escape using a polymeric nanocomplex of paclitaxel (PTX)-encapsulated sulfobutylether-β-cyclodextrin (SBE)/mannosylated N,N,N-trimethylchitosan (mTMC)/DNA. To enhance DC-targeting and revoke immunosuppression is the major challenge for eliciting effective antitumor immunity. This codelivery system is characterized by using low-dose PTX as an adjuvant that is included inside SBE, and the PTX/SBE further serves as an anionic crosslinker to self-assemble with the cationic mTMC/DNA polyplexes. This system is used in combination with a microneedle for transcutaneous vaccination. Once penetrating into the epidermis, the mannosylated nanocomplexes would preferentially deliver the pTRP-2 DNA vaccine inside the DCs. Phenotypic maturation is demonstrated by the increased expression of costimulatory molecules of CD80 and CD86, and the elevated secretion of IL-12p70. The mixed leucocyte reactions reveal that the PTX/SBE-mTMC/DNA nanocomplexes enhance the proliferation of CD4+ and CD8+ T cells, and inhibit the generation of immune-suppressive FoxP3+ T cells. The system shows high antitumor efficacy in vivo. The PTX/SBE-mTMC/DNA nanocomplexes for DC-targeted codelivery of DNA vaccine and adjuvant PTX yield synergistic effects on the DC maturation and its presenting functions, thus increasing immune stimulation and reducing immune escape.

Mutations in Human Interferon α2b Gene and Potential as Risk Factor Associated with Female Breast Cancer

The current study explored the potential links between breast cancer and human interferon α-2b (hIFNα-2b) gene mutations. The hIFNα-2b gene was amplified from breast cancer tumor tissue samples (N = 60) by polymerase chain reaction (PCR) and the products were subjected to gene sequencing. A total of 38 (63.3%) samples showed positive PCR amplification results. Several of these also exhibited frequent alterations (mutations) after 400 bp and, in particular, adenine was replaced by other bases. A total of 19 selected mutated amino acids were analyzed for local/general fold pattern changes. Human IFNα-2b receptor (IFNAR): ligand (hIFNα-2b protein) interactions through a Z-DOCK (3.0.2) server were also evaluated to assess the binding patterns of each ligand to receptor to induce Janus-Kinase-signal transducer and activator of transcription antiproliferative signal transduction pathway inside the cancer cells. Certain local structural and conformational changes were predicted to be induced by mutations in the ligand. The variant models of the hIFNα-2b displayed structural and conformational changes that signified that changes to hIFNα-2b may be a risk factor in addition to other known factors associated with onset/progression of female breast carcinoma. It was hoped that others might build upon the research in this study evaluating protein structural models with mutations and their consequent interactions with receptors in the development of potent immune therapeutic drugs for breast cancer that are based on recombinant hIFNα-2b.

Composite peptide-based vaccines for cancer immunotherapy (Review)

The use of peptide-based vaccines as therapeutics aims to elicit immune responses through antigenic epitopes derived from tumor antigens. Peptide-based vaccines are easily synthesized and chemically stable entities, and of note, they are absent of oncogenic potential. However, their application is more complicated as the success of an effective peptide-based vaccine is determined by numerous parameters. The success thus far has been limited by the choice of tumor antigenic peptides, poor immunogenicity and incorporation of strategies to reverse cancer-mediated immune suppression. In the present review, an overview of the mechanisms of peptide-based vaccines is provided and antigenic peptides are categorized with respect to their tissue distribution in order to determine their usefulness as targets. Furthermore, certain approaches are proposed that induce and maintain T cells for immunotherapy. The recent progress indicates that peptide-based vaccines are preferential for targeted therapy in cancer patients.

The immunological and clinical effects of mutated ras peptide vaccine in combination with IL-2, GM-CSF, or both in patients with solid tumors

Background

Mutant Ras oncogenes produce proteins that are unique to cancer cells and represent attractive targets for vaccine therapy. We have shown previously that vaccinating cancer patients with mutant ras peptides is feasible and capable of inducing a specific immune response against the relevant mutant proteins. Here, we tested the mutant ras peptide vaccine administered in combination with low dose interleukin-2 (IL-2) or/and granulocyte-macrophage colony-stimulating factor (GM-CSF) in order to enhance the vaccine immune response.

Methods

5000μg of the corresponding mutant ras peptide was given subcutaneously (SQ) along with IL-2 (Arm A), GM-CSF (Arm B) or both (Arm C). IL-2 was given SQ at 6.0 million IU/m²/day starting at day 5, 5 days/week for 2 weeks. GM-CSF was given SQ in a dose of 100μg/day one day prior to each ras peptide vaccination for 4 days. Vaccines were repeated every 5 weeks on arm A and C, and every 4 weeks on arm B, for a maximum of 15 cycles or until disease progression.

Results

We treated 53 advanced cancer patients (38 with colorectal, 11 with pancreatic, 1 with common bile duct and 3 with lung) on 3 different arms (16 on arm A, 18 on arm B, and 19 on arm C). The median progression free survival (PFS) and overall survival (OS) was 3.6 and 16.9 months, respectively, for all patients evaluable for clinical response (n = 48). There was no difference in PFS or OS between the three arms (P = 0.73 and 0.99, respectively). Most adverse events were grade 1-2 toxicities and resolved spontaneously. The vaccine induced an immune response to the relevant ras peptide in a total of 20 out of 37 evaluable patients (54%) by ELISPOT, proliferative assay, or both. While 92.3% of patients on arm B had a positive immune response, only 31% of patients on arm A and 36% of patients on arm C had positive immune responses (P = 0.003, Fisher’s exact test).

Conclusions

The reported data showed that IL-2 might have a negative effect on the specific immune response induced by the relevant mutant ras vaccine in patients with advanced cancer. This observation deserves further investigations.

Trial registration

NCI97C0141

Adjuvant therapy for malignant melanoma

Malignant melanoma is increasing in incidence worldwide, and many patients remain at a significant risk of recurrence following surgical resection. Over the past 30 years, interferon-alpha has been the only agent approved for adjuvant therapy of melanoma. This review summarizes the rationale for adjuvant therapy, and discusses the roles of interferon, immunotherapy, chemotherapy and radiation therapy in the adjuvant setting. New approaches and novel combinations that appear promising for the adjuvant therapy of malignant melanoma are also outlined.

Helper cell-independent antitumor activity of potent CD8+ T cell epitope peptide vaccines is dependent upon CD40L

Peptide vaccines derived from CD8⁺ T-cell epitopes have shown variable efficacy in cancer patients. Thus, some peptide vaccines are capable of activating CD8⁺ T-cell responses, even in the absence of CD4⁺ T-cell epitopes or dendritic cell (DC)-activating adjuvants. However, the mechanisms underlying the clinical activity of these potent peptides are poorly understood. Using CT26 and ovalbumin-expressing B16 murine allograft tumor models, we found that the antitumor effect of helper cell-independent CD8 T-cell peptide vaccines is inhibited by the blockade of CD40 ligand (CD40L) in vivo. Furthermore, in vitro stimulation with antigenic peptides of cells derived from immunized mice induced the expression of CD40L on the surface of CD8⁺ T cells and fostered DC maturation, an effect that was partially inhibited by CD40L-blocking antibodies. Interestingly, CD40L blockade also inhibited CD8⁺ T-cell responses, even in the presence of fully mature DCs, suggesting a role for CD40L not only in promoting DC maturation but also in mediating CD8⁺ T-cell co-stimulation. Importantly, these potent peptides share features with bona fide CD4 epitopes, since they foster responses against less immunogenic CD8⁺ T-cell epitopes in a CD40L-dependent manner. The analysis of peptides used for the vaccination of cancer patients in clinical trials showed that these peptides also induce the expression of CD40L on the surface of CD8⁺ T cells. Taken together, these results suggest that CD40L expression induced by potent CD8⁺ T-cell epitopes can activate antitumor CD8⁺ T-cell responses, potentially amplifying the immunological responses to less immunogenic CD8⁺ T-cell epitopes and bypassing the requirement for CD4⁺ helper T cells in vaccination protocols.

Granulocyte-Macrophage Colony Stimulating Factor: An Adjuvant for Cancer Vaccines

Granulocyte-macrophage colony stimulating factor (GM-CSF) enhances immune responses by inducing the proliferation, maturation, and migration of dendritic cells, and the expansion and differentiation of B and T lymphocytes. There is significant data in pre-clinical animal models demonstrating the adjuvant effects of GM-CSF in a variety of cancer vaccine approaches, including cellular vaccines, viral vaccines, peptide and protein vaccines, and DNA vaccines. GM-CSF is an attractive vaccine adjuvant because of its immune modulation effects and low toxicity profile. The results in animal models have been confirmed in pilot clinical trials and several clinical trials are currently ongoing.

Prospects of combinatorial synthetic peptide vaccine-based immunotherapy against cancer

The insight that the immune system is involved in tumor resistance is gaining momentum and this has led to the development of immunotherapeutic strategies aiming at enhancement of immune-mediated tumor destruction. Although some of these strategies have moderate clinical benefit, most stand-alone therapies fail to significantly affect progressive disease and survival or do so only in a minority of patients. Research on the mechanisms underlying the generation of immune responses against tumors and the immune evasion by tumors has emphasized that various mechanisms simultaneously prevent effective immunity against cancer including inefficient presentation of tumor antigens by dendritic cells and induction of negative immune regulation by regulatory T-cells (Tregs) and myeloid derived suppressor cells (MDSCs). Thus the design of therapies that simultaneously improve effective tumor immunity and counteract immune evasion by tumors seems most desirable for clinical efficacy. As it is unlikely that a single immunotherapeutic strategy addresses all necessary requirements, combinatorial strategies that act synergistically need to be developed. Here we discuss the current knowledge and prospects of treatment with synthetic peptide vaccines that stimulate tumor-specific T-cell responses combined with adjuvants, immune modulating antibodies, cytokines and chemotherapy. We conclude that combinatorial approaches have the best potency to accomplish the most significant tumor destruction but further research is required to optimize such approaches.

Cancer stem cell antigen-based vaccines: the preferred strategy for active specific immunotherapy of metastatic melanoma?

INTRODUCTION

There are now two chemotherapy agents, one tyrosine kinase inhibitor and three immunotherapy products approved for the treatment of metastatic melanoma, but an unmet need persists because these options are toxic and of limited therapeutic benefit. Active specific immunotherapy with therapeutic vaccines could be a useful addition to the therapeutic armamentarium, especially in patients whose tumor burden has been reduced by other treatment modalities.

AREAS COVERED

This article reviews various sources of melanoma antigens, such as peptides, gangliosides, autologous tumor and cancer stem cells including allogeneic and autologous cell lines. The advantages and disadvantages of various antigen sources and allogeneic and autologous approaches are discussed with an emphasis on the theoretical benefits of immunizing against cancer stem cells. The results from published randomized trials testing the benefit of various vaccine approaches are summarized, as well as promising results from three Phase II trials (one randomized) of patient-specific stem cell antigen-based products.

EXPERT OPINION

Immune responses directed toward the unique neoantigens and stem cell antigens expressed on continuously proliferating, self-renewing, autologous tumor cells could potentially overcome the limitations inherent in these other antigen-based approaches, that to date, have yielded disappointing results in randomized trials.

Targeted therapy in renal cell carcinoma: moving from molecular agents to specific immunotherapy

Non-specific immunotherapy has been for a long time a standard treatment option for patients with metastatic renal cell carcinoma but was redeemed by specific targeted molecular therapies, namely the VEGF and mTOR inhibitors. After moving treatment for mRCC to specific molecular agents with a well-defined mode of action, immunotherapy still needs this further development to increase its accuracy. Nowadays, an evolution from a rather non-specific cytokine treatment to sophisticated targeted approaches in specific immunotherapy led to a re-launch of immunotherapy in clinical studies. Recent steps in the development of immunotherapy strategies are discussed in this review with a special focus on peptide vaccination which aims at a tumor targeting by specific T lymphocytes. In addition, different combinatory strategies with immunomodulating agents like cyclophosphamide or sunitinib are outlined, and the effects of immune checkpoint modulators as anti-CTLA-4 or PD-1 antibodies are discussed.

Evaluation of a method for the simultaneous detection of multiple tumor markers using a multiplex suspension bead array

OBJECTIVE

To achieve higher tumor detection efficiency, we evaluated a multiplex assay for TM analysis based on the Luminex-100 multiplex suspension bead array.

DESIGN

The assay simultaneously determined the concentrations of nine TMs in 1114 human serum specimens (546 patients with tumors, 158 patients with non-tumor inflammatory diseases, and 410 normal controls). The nine TMs were AFP, CEA, CA125, CYFRA 21-1, CA242, f-PSA, t-PSA, NSE and free β-hCG. The multiplex suspension bead assays were compared with conventional methods used in clinical laboratories.

RESULTS

The Luminex assay has the same levels of sensitivity, specificity and accuracy in the prediction of positive tumor specimens as conventional methods.

CONCLUSION

Multiplex suspension bead arrays have promising applications in clinical laboratories.

Melanoma vaccines: developments over the past 10 years

Decades of preclinical evaluation and clinical trials into melanoma vaccines have yielded spectacular progress in our understanding of melanoma antigens and the immune mechanisms of tumor rejection. Key insights and the results of their clinical evaluation are reviewed in this article. Unfortunately, durable clinical benefit following vaccination remains uncommon. Two recent clinical advances that will impact on melanoma vaccine development are trials with inhibitors of CTLA-4 and oncogenic BRAF. Long-term therapeutic control of melanoma will require integration of specific active immunotherapy with these emerging successful therapies from the disparate fields of immune regulation and signal transduction.

A gynecologic oncology group phase II trial of two p53 peptide vaccine approaches: subcutaneous injection and intravenous pulsed dendritic cells in high recurrence risk ovarian cancer patients

PURPOSE

Peptide antigens have been administered by different approaches as cancer vaccine therapy, including direct injection or pulsed onto dendritic cells; however, the optimal delivery method is still debatable. In this study, we describe the immune response elicited by two vaccine approaches using the wild-type (wt) p53 vaccine.

EXPERIMENTAL DESIGN

Twenty-one HLA-A2.1 patients with stage III, IV, or recurrent ovarian cancer overexpressing the p53 protein with no evidence of disease were treated in two cohorts. Arm A received SC wt p53:264-272 peptide admixed with Montanide and GM-CSF. Arm B received wt p53:264-272 peptide-pulsed dendritic cells IV. Interleukin-2 (IL-2) was administered to both cohorts in alternative cycles.

RESULTS

Nine of 13 patients (69%) in arm A and 5 of 6 patients (83%) in arm B developed an immunologic response as determined by ELISPOT and tetramer assays. The vaccine caused no serious systemic side effects. IL-2 administration resulted in grade 3 and 4 toxicities in both arms and directly induced the expansion of T regulatory cells. The median overall survival was 40.8 and 29.6 months for arm A and B, respectively; the median progression-free survival was 4.2 and. 8.7 months, respectively.

CONCLUSION

We found that using either vaccination approach generates comparable specific immune responses against the p53 peptide with minimal toxicity. Accordingly, our findings suggest that the use of less demanding SC approach may be as effective. Furthermore, the use of low-dose SC IL-2 as an adjuvant might have interfered with the immune response. Therefore, it may not be needed in future trials.

Cytokine adjuvants for vaccine therapy of neoplastic and infectious disease

Vaccination, the revolutionary prophylactic immunotherapy developed in the eighteenth century, has become the most successful and cost-effective of medical remedies available to modern society. Due to the remarkable accomplishments of the past century, the number of diseases and pathogens for which a traditional vaccine approach might reasonably be employed has dwindled to unprecedented levels. While this happy scenario bodes well for the future of public health, modern immunologists and vaccinologists face significant challenges if we are to address the scourge of recalcitrant pathogens like HIV and HCV and well as the significant obstacles to immunotherapy imposed by neoplastic self. Here, the authors review the clinical and preclinical literature to highlight the manner by which the host immune system can be successfully manipulated by cytokine adjuvants, thereby significantly enhancing the efficacy of a wide variety of vaccination platforms.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

MHC class I-presented tumor antigens identified in ovarian cancer by immunoproteomic analysis are targets for T-cell responses against breast and ovarian cancer

PURPOSE

The purpose of this study is to test whether peptide epitopes chosen from among those naturally processed and overpresented within MHC molecules by malignant, but not normal cells, when formulated into cancer vaccines, could activate antitumor T-cell responses in humans.

EXPERIMENTAL DESIGN

Mixtures of human leukocyte antigen A2 (HLA-A2)-binding ovarian cancer-associated peptides were used to activate naive T cells to generate antigen-specific T cells that could recognize ovarian and breast cancers in vitro. Combinations of these peptides (0.3 mg of each peptide or 1 mg of each peptide) were formulated into vaccines in conjunction with Montanide ISA-51 and granulocyte monocyte colony stimulating factor which were used to vaccinate patients with ovarian and breast cancer without evidence of clinical disease in parallel pilot clinical trials.

RESULTS

T cells specific for individual peptides could be generated in vitro by using mixtures of peptides, and these T cells recognized ovarian and breast cancers but not nonmalignant cells. Patient vaccinations were well tolerated with the exception of local erythema and induration at the injection site. Nine of the 14 vaccinated patients responded immunologically to their vaccine by inducing peptide-specific T-cell responses that were capable of recognizing HLA-matched breast and ovarian cancer cells.

CONCLUSION

Mixtures of specific peptides identified as naturally presented on cancer cells and capable of activating tumor-specific T cells in vitro also initiate or augment immune responses toward solid tumors in cancer patients.

Antitumor effects of combined granulocyte macrophage colony stimulating factor and macrophage inflammatory protein-3 alpha plasmid DNA

Dendritic cells (DC) are critical for priming adaptive immune responses to foreign antigens. However, the feasibility of harnessing these cells in vivo to optimize the antitumor effects has not been fully explored. The authors investigated a novel therapeutic approach that involves delivering synergistic signals that both recruit and expand DC populations at sites of intratumoral injection. More specifically, the authors examined whether the co-administration of plasmids encoding the chemokine macrophage inflammatory protein-3 alpha (pMIP3α) and plasmid encoding the granulocyte macrophage colony stimulating factor (pGM-CSF; a DC-specific growth factor) can recruit, expand and activate large numbers of DC at sites of intratumoral injection. It was found that the administration of pGM-CSF and pMIP3α resulted in dramatic recruitment and expansion of DC at these sites and in draining lymph nodes. Furthermore, treatment with pGM-CSF and pMIP3α generated the strongest MUC1-associated CD8+ T-cell immune responses in draining lymph nodes and in tumors, produced the greatest antitumor effects and enhanced survival rates more than pcDNA3.1, pGM-CSF alone and pMIP3α alone. It was also found that pGM-CSF plus pMIP3α generated the strongest MUC1-associated CD4+ T-cell immune responses in draining lymph nodes and in tumors. The findings of the present study suggest that the recruitment and activation of DC in vivo due to the synergistic actions of pGM-CSF and pMIP3α presents a potentially feasible means of controlling immunogenic malignancies and provides a basis for the development of novel immunotherapeutic treatments.

CpG Oligodeoxynucleotides Enhance the Activities of CD8+ Cytotoxic T-Lymphocytes Generated by Combined hMUC1 Vaccination and hNIS Radioiodine Gene Therapy

PURPOSE

The authors evaluated whether the cytotoxicity of CD8+CTLs generated by combined hMUC1 vaccination and hNIS radioiodine gene therapy was enhanced in the presence of CpG in an established tumor model.

METHODS

CMNF cells (CT26 cells expressing hMUC1, hNIS and Firefly luciferase) were transplanted into BALB/c mice. Four and 10 days later, tumor-bearing mice were immunized intramuscularly with pcDNA3.1 or pcDNA-hMUC1 or pcDNA-hMUC1+CpG, and subsequently administered PBS or (131)I [five groups (seven mice/group): referred to as the pcDNA3.1+PBS, phMUC1+PBS, pcDNA3.1+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG groups]. The number of CD8+IFNr+ T cells of splenocytes as well as the number of CD8+IFNr+ T cells of splenocytes re-stimulated with CD11c+ cells was determined using FACS analysis. The activities of cytotoxic T cells (CTLs) from splenocytes were investigated.

RESULTS

Marked tumor growth inhibition was observed in the phMUC1+(131)I and phMUC1+(131)I+CpG groups, but not in the other three single therapy groups. Particularly the number of CD8+IFN-γ+ T cells of splenocytes was more increased in the phMUC1+(131)I+CpG group than in the phMUC1+(131)I group. The number of CD8+IFN-γ+ T cells of splenocytes stimulated with CD11c+ cells was the most enhanced in the phMUC1+(131)I+CpG group among the five groups. Concurrently, the activities of hMUC1-associated CTLs obtained from splenocytes in the phMUC1+(131)I+CpG group were significantly greater than in the other four groups (pcDNA+PBS, phMUC1+PBS, pcDNA+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG, 16 ± 2%, 20 ± 1%, 30 ± 2%, 60 ± 2%, and 87 ± 2%, respectively, P < 0.01).

CONCLUSION

Our data suggest that adjuvant CpG ODNs can increase the killing activities of CTLs generated by combined hMUC1 DNA vaccination and hNIS radioiodine gene therapy.

Peptide vaccines prevent tumor growth by activating T cells that respond to native tumor antigens

Peptide vaccines enhance the response of T cells toward tumor antigens and represent a strategy to augment antigen-independent immunotherapies of cancer. However, peptide vaccines that include native tumor antigens rarely prevent tumor growth. We have assembled a set of peptide variants for a mouse-colon tumor model to determine how to improve T-cell responses. These peptides have similar affinity for MHC molecules, but differ in the affinity of the peptide-MHC/T-cell receptor interaction with a tumor-specific T-cell clone. We systematically demonstrated that effective antitumor responses are generated after vaccination with variant peptides that stimulate the largest proportion of endogenous T cells specific for the native tumor antigen. Importantly, we found some variant peptides that strongly stimulated a specific T-cell clone in vitro, but elicited fewer tumor-specific T cells in vivo, and were not protective. The T cells expanded by the effective vaccines responded to the wild-type antigen by making cytokines and killing target cells, whereas most of the T cells expanded by the ineffective vaccines only responded to the peptide variants. We conclude that peptide-variant vaccines are most effective when the peptides react with a large responsive part of the tumor-specific T-cell repertoire.

Comparison of hospitalization risk and associated costs among patients receiving sargramostim, filgrastim, and pegfilgrastim for chemotherapy-induced neutropenia

BACKGROUND

Sargramostim is a granulocyte-macrophage-colony-stimulating factor (GM-CSF). Unlike filgrastim and pegfilgrastim, which are granulocyte-colony-stimulating factors (G-CSFs), sargramostim activates a broader range of myeloid lineage-derived cells. Therefore, GM-CSF might reduce infection risk more than the G-CSFs. This study compared real-world infection-related hospitalization rates and costs in patients using G/GM-CSF for chemotherapy-induced neutropenia.

METHODS

This retrospective matched-cohort study analyzed nationally representative health insurance claims in the United States from 2000 through 2007. The sample population included patients who received chemotherapy and G/GM-CSF. G/GM-CSF treatment episodes began with the first administration of G/GM-CSF and ended when a subsequent administration was >28 days after a prior administration. Sargramostim patients were matched 1:1 with filgrastim and pegfilgrastim patients based on gender and birth year. Outcomes included infection-related hospitalization rates and the associated costs. Hospitalization rates were analyzed using univariate and multivariate Poisson methods; covariates included myelosuppressive agents received, tumor type, anemia, and comorbidities.

RESULTS

A total of 990 sargramostim-filgrastim and 982 sargramostim-pegfilgrastim matched pairs were analyzed. Cohorts were similar with regard to age, gender, and comorbid conditions. Several differences were observed with regard to tumor type, anemia, and chemotherapy, but no systematic trends were apparent. Sargramostim patients experienced a 56% lower risk of infection-related hospitalizations compared with filgrastim and pegfilgrastim patients. Infection-related hospitalization costs were 84% and 62% lower for sargramostim patients compared with patients treated with filgrastim and pegfilgrastim, respectively.

CONCLUSIONS

Among patients with or at risk for chemotherapy-induced neutropenia, these data indicated that use of sargramostim was associated with a reduced risk of infection-related hospitalization and lower associated costs compared with filgrastim or pegfilgrastim.

Effect of granulocyte/macrophage colony-stimulating factor on vaccination with an allogeneic whole-cell melanoma vaccine

PURPOSE

The availability of a variety of immune response modifiers creates an opportunity for improved efficacy of immunotherapy, but it also leads to uncertainty in how to combine agents and how to assess those combinations. We sought to assess the effect of the addition of granulocyte/macrophage colony-stimulating factor (GM-CSF) to vaccination with a melanoma vaccine.

EXPERIMENTAL DESIGN

Ninety-seven patients with resected melanoma (stage II-IV) were enrolled, stratified by stage, and randomized to receive a cellular melanoma vaccine with or without GM-CSF. The primary endpoint was delayed-type hypersensitivity (DTH) response to melanoma cells. Antibody responses, peripheral leukocyte counts, and survival were also examined.

RESULTS

The GM-CSF arm showed enhanced antibody responses with an increase in IgM titer against the TA90 antigen and increased TA90 immune complexes. This arm also had diminished antimelanoma cell delayed-type hypersensitivity response. Peripheral blood leukocyte profiles showed increases in eosinophils and basophils with decreased monocytes in the GM-CSF arm. These immune changes were accompanied by an increase in early melanoma deaths and a trend toward worse survival with GM-CSF.

CONCLUSION

These data suggest that GM-CSF is not helpful as an immune adjuvant in this dose and schedule and raise concern that it may be harmful. Based on the discordant findings of an immune endpoint and clinical outcome, the use of such surrogate endpoints in selecting treatments for further evaluation must be done with a great deal of caution.

Design of clinical trials for therapeutic cancer vaccines development

Advances in molecular and cellular biology as well as biotechnology led to definition of a group of drugs referred to as medicinal products of advanced technologies. It includes gene therapy products, somatic cell therapeutics and tissue engineering. Therapeutic cancer vaccines including whole cell tumor cells vaccines or gene modified whole cells belong to somatic therapeutics and/or gene therapy products category. The drug development is a multistep complex process. It comprises of two phases: preclinical and clinical. Guidelines on preclinical testing of cell based immunotherapy medicinal products have been defined by regulatory agencies and are available. However, clinical testing of therapeutic cancer vaccines is still under debate. It presents a serious problem since recently clinical efficacy of the number of cancer vaccines has been demonstrated that focused a lot of public attention. In general clinical testing in the current form is very expensive, time consuming and poorly designed what may lead to overlooking of products clinically beneficial for patients. Accordingly regulatory authorities and researches including Cancer Vaccine Clinical Trial Working Group proposed three regulatory solutions to facilitate clinical development of cancer vaccines: cost-recovery program, conditional marketing authorization, and a new development paradigm. Paradigm includes a model in which cancer vaccines are investigated in two types of clinical trials: proof-of-principle and efficacy. The proof-of-principle trial objectives are: safety; dose selection and schedule of vaccination; and demonstration of proof-of-principle. Efficacy trials are randomized clinical trials with objectives of demonstrating clinical benefit either directly or through a surrogate. The clinical end points are still under debate.

Vaccination with agonist peptide PSA: 154-163 (155L) derived from prostate specific antigen induced CD8 T-cell response to the native peptide PSA: 154-163 but failed to induce the reactivity against tumor targets expressing PSA: a phase 2 study in patients with recurrent prostate cancer

We conducted a clinical trial of peptide prostate specific antigen (PSA): 154-163 (155L) vaccination in human leukocyte antigen (HLA)-A2 patients with detectable and rising serum PSA after radical prostatectomy for prostate cancer (Clinicaltrials.gov identifier NCT00109811). The trial was a single dose-level, phase 2 pilot trial of 1 mg of PSA: 154-163 (155L) emulsified with adjuvant (Montanide ISA-51). The primary endpoint was the determination of immunogenicity of the vaccine; secondary outcomes were determination of toxicity and effect on serum PSA. The vaccine was given subcutaneously 7 times on weeks 0, 2, 4, 6, 10, 14, and 18. Peptide-specific CD8 T-cell responses in the peripheral blood mononuclear cells (PBMC) of patients were measured by interferon (IFN)-gamma enzyme-linked immunosorbent spot assay. CD8 T-cell cultures were also established by in vitro stimulation with the peptide presented by autologous dendritic cells. Five patients were enrolled and completed all vaccinations. No IFN-gamma response to PSA: 154-163 (155L) was detected in unfractioned PBMC in any patient either before or after vaccination. Three of 5 patients demonstrated strong IFN-gamma responses to PSA: 154-163 (155L) and native PSA: 154-163 peptides in CD8 T-cell cultures derived from postvaccination PBMC. However, peptide-specific T cells failed to recognize HLA-A2 positive targets expressing endogenous PSA. There were no significant changes in serum PSA level in any subject. No serious adverse events were observed. PSA: 154-163 (155L) is not an effective immunogen when given with Montanide ISA-51. The PSA: 154-163 peptide is poorly processed from endogenous PSA and therefore represents a cryptic epitope of PSA in HLA-A2 antigen-presenting cells.

A phase II study of oxaliplatin, docetaxel, and GM-CSF in patients with previously treated advanced melanoma

PURPOSE

Although much focus has been placed on immunotherapy for melanoma, further development of chemotherapy approaches is needed. Melanoma is responsive to platinum compounds and taxanes, but there is limited experience with combinations of these agents. Oxaliplatin has been reported to have detectable activity in melanoma, and a phase I study has identified a tolerable dose and schedule of oxaliplatin in combination with docetaxel and hematopoietic growth factor support. GM-CSF has a theoretical advantage of immune potentiation. These considerations supported the study of oxaliplatin, docetaxel, and GM-CSF in patients with advanced melanoma.

METHODS

Eligibility included adequate organ function, PS<or=2, at most one prior chemotherapy and one prior immunotherapy, no prior treatment with oxaliplatin or taxanes and no chremophor allergy. After premedication, docetaxel was administered day 1 at 75 mg/m2, then oxaliplatin on day 2 at 85 mg/m2. GM-CSF (250 mcg/m2) was administered s.c. days 3-12. Cycles were 21 days in length, and disease reevaluation was performed every two cycles by RECIST criteria.

RESULTS

Nineteen patients received at least one cycle, eight with one prior systemic therapy, five with two prior systemic therapies. Five patients did not complete two cycles and were not formally evaluable for response. Five patients had stable disease (SD), including one who failed two prior therapies and went on to receive ten cycles. The remaining nine patients displayed progressive disease (PD) after two cycles. Notable toxicities included seven cases (37%) of grade III/IV neutropenia and two (11%) hypersensitivity reactions.

CONCLUSIONS

This combination of oxaliplatin, docetaxel, and GM-CSF has limited clinical activity in previously treated patients with advanced melanoma. Exploration in treatment-naïve patients may still be warranted.

Impaired interferon signaling is a common immune defect in human cancer

Immune dysfunction develops in patients with many cancer types and may contribute to tumor progression and failure of immunotherapy. Mechanisms underlying cancer-associated immune dysfunction are not fully understood. Efficient IFN signaling is critical to lymphocyte function; animals rendered deficient in IFN signaling develop cancer at higher rates. We hypothesized that altered IFN signaling may be a key mechanism of immune dysfunction common to cancer. To address this, we assessed the functional responses to IFN in peripheral blood lymphocytes from patients with 3 major cancers: breast cancer, melanoma, and gastrointestinal cancer. Type-I IFN (IFN-alpha)-induced signaling was reduced in T cells and B cells from all 3 cancer-patient groups compared to healthy controls. Type-II IFN (IFN-gamma)-induced signaling was reduced in B cells from all 3 cancer patient groups, but not in T cells or natural killer cells. Impaired-IFN signaling was equally evident in stage II, III, and IV breast cancer patients, and downstream functional defects in T cell activation were identified. Taken together, these findings indicate that defects in lymphocyte IFN signaling arise in patients with breast cancer, melanoma, and gastrointestinal cancer, and these defects may represent a common cancer-associated mechanism of immune dysfunction.

Antimicrobial effects of interferon-inducible CXC chemokines against Bacillus anthracis spores and bacilli

Based on previous studies showing that host chemokines exert antimicrobial activities against bacteria, we sought to determine whether the interferon-inducible Glu-Leu-Arg-negative CXC chemokines CXCL9, CXCL10, and CXCL11 exhibit antimicrobial activities against Bacillus anthracis. In vitro analysis demonstrated that all three CXC chemokines exerted direct antimicrobial effects against B. anthracis spores and bacilli including marked reductions in spore and bacillus viability as determined using a fluorometric assay of bacterial viability and CFU determinations. Electron microscopy studies revealed that CXCL10-treated spores failed to undergo germination as judged by an absence of cytological changes in spore structure that occur during the process of germination. Immunogold labeling of CXCL10-treated spores demonstrated that the chemokine was located internal to the exosporium in association primarily with the spore coat and its interface with the cortex. To begin examining the potential biological relevance of chemokine-mediated antimicrobial activity, we used a murine model of inhalational anthrax. Upon spore challenge, the lungs of C57BL/6 mice (resistant to inhalational B. anthracis infection) had significantly higher levels of CXCL9, CXCL10, and CXCL11 than did the lungs of A/J mice (highly susceptible to infection). Increased CXC chemokine levels were associated with significantly reduced levels of spore germination within the lungs as determined by in vivo imaging. Taken together, our data demonstrate a novel antimicrobial role for host chemokines against B. anthracis that provides unique insight into host defense against inhalational anthrax; these data also support the notion for an innovative approach in treating B. anthracis infection as well as infections caused by other spore-forming organisms.

Advanced Liposomal Vectors as Cancer Vaccines in Melanoma Immunotherapy

Malignant tumors represent a major source of disability and account for more than one of five deaths in Western countries. Among the different cancers, melanoma harbors two distinctive features. First, its has long been recognized as an immunogenic tumor, and second, an unprecedented rise in incidence is currently observed, in face of few therapeutic options. Thus, melanoma represent an ideal target for a cancer immunotherapy program. To date, a number of immunodominant epitopes from tumor associated antigens (TAA) are used as cancer vaccines in clinical trials, in spite of an acknowledged rapid degradation in vivo and low immunogenicity. However, most of the immunotherapy trials reported so far do not achieve consistent clinical results. Hence, there is an urgent need for the development of a carrier system and strong adjuvants suitable for a TAA-based cancer immunotherapy. Liposomes and their further development as virosomes with added adjuvancy may address both these issues. We report here our experience in the tailoring of dedicated advanced liposomal vectors that were developed in the context of an upcoming immunotherapy clinical trial for melanoma.