Immunological effects of BCG as an adjuvant in autologous tumor vaccines

Immunotherapy and Prevention of Cancer by Nanovaccines Loaded with Whole-Cell Components of Tumor Tissues or Cells

Tumor tissues/cells are the best sources of antigens to prepare cancer vaccines. However, due to the difficulty of solubilization and delivery of water-insoluble antigens in tumor tissues/cells, including water-insoluble antigens into cancer vaccines and delivering such vaccines efficiently to antigen-presenting cells (APCs) remain challenging. To solve these problems, herein, water-insoluble components of tumor tissues/cells are solubilized by 8 m urea and thus whole components of micrometer-sized tumor cells are reasssembled into nanosized nanovaccines. To induce maximized immunization efficacy, various antigens are loaded both inside and on the surface of nanovaccines. By encapsulating both water-insoluble and water-soluble components of tumor tissues/cells into nanovaccines, the nanovaccines are efficiently phagocytosed by APCs and showed better therapeutic efficacy than the nanovaccine loaded with only water-soluble components in melanoma and breast cancer. Anti-PD-1 antibody and metformin can improve the efficacy of nanovaccines. In addition, the nanovaccines can prevent lung cancer (100%) and melanoma (70%) efficiently in mice. T cell analysis and tumor microenvironment analysis indicate that tumor-specific T cells are induced by nanovaccines and both adaptive and innate immune responses against cancer cells are activated by nanovaccines. Overall, this study demonstrates a universal method to make tumor-cell-based nanovaccines for cancer immunotherapy and prevention.

Repurposing Infectious Diseases Vaccines Against Cancer

Vaccines used to prevent infections have long been known to stimulate immune responses to cancer as illustrated by the approval of the Bacillus Calmette-Guérin (BCG) vaccine to treat bladder cancer since the 1970s. The recent approval of immunotherapies has rejuvenated this research area with reports of anti-tumor responses with existing infectious diseases vaccines used as such, either alone or in combination with immune checkpoint inhibitors. Here, we have reviewed and summarized research activities using approved vaccines to treat cancer. Data supporting a cancer therapeutic use was found for 16 vaccines. For 10 (BCG, diphtheria, tetanus, human papillomavirus, influenza, measles, pneumococcus, smallpox, typhoid and varicella-zoster), clinical trials have been conducted or are ongoing. Within the remaining 6, preclinical evidence supports further evaluation of the rotavirus, yellow fever and pertussis vaccine in carefully designed clinical trials. The mechanistic evidence for the cholera vaccine, combined with the observational data in colorectal cancer, is also supportive of clinical translation. There is limited data for the hepatitis B and mumps vaccine (without measles vaccine). Four findings are worth highlighting: the superiority of intravesical typhoid vaccine instillations over BCG in a preclinical bladder cancer model, which is now the subject of a phase I trial; the perioperative use of the influenza vaccine to limit and prevent the natural killer cell dysfunction induced by cancer surgery; objective responses following intratumoral injections of measles vaccine in cutaneous T-cell lymphoma; objective responses induced by human papillomavirus vaccine in cutaneous squamous cell carcinoma. All vaccines are intended to induce or improve an anti-tumor (immune) response. In addition to the biological and immunological mechanisms that vary between vaccines, the mode of administration and sequence with other (immuno-)therapies warrant more attention in future research.

Reconcile the debate over protective effects of BCG vaccine against COVID-19

While awaiting the COVID-19 vaccines, researchers have been actively exploring the effectiveness of existing vaccines against the new virus, among which the BCG vaccine (Bacillus Calmette-Guérin) receives the most attention. While many reports suggest a potential role for BCG immunization in ameliorating SARS-CoV-2 infection, these findings remain controversial. With country-level COVID-19 outbreak data from Johns Hopkins University Coronavirus Resource Center, and BCG program data from World Atlas of BCG Policies and Practices and WHO/UNICE, we estimated a dynamic model to investigate the effect of BCG vaccination across time during the pandemic. Our results reconcile these varying reports regarding protection by BCG against COVID-19 in a variety of clinical scenarios and model specifications. We observe a notable protective effect of the BCG vaccine during the early stage of the pandemic. However, we do not see any strong evidence for protection during the later stages. We also see that a higher proportion of vaccinated young population may confer some level of communal protection against the virus in the early pandemic period, even when the proportion of vaccination in the older population is low. Our results highlight that while BCG may offer some protection against COVID-19, we should be cautious in interpreting the estimated effectiveness as it may vary over time and depend on the age structure of the vaccinated population.

Early Events of the Reaction Elicited by CSF-470 Melanoma Vaccine Plus Adjuvants: An In Vitro Analysis of Immune Recruitment and Cytokine Release

In a previous work, we showed that CSF-470 vaccine plus bacillus Calmette–Guerin (BCG) and granulocyte macrophage colony-stimulating factor (GM-CSF) as adjuvants resulted in a significant benefit in the distant metastasis-free survival when comparing vaccinated vs. IFN-α2b-treated high-risk cutaneous melanoma patients in a Phase II study. Immune monitoring demonstrated an increase in anti-tumor innate and adaptive immunities of vaccinated patients, with a striking increase in IFN-γ secreting lymphocytes specific for melanoma antigens (Ags). In an effort to dissect the first steps of the immune response elicited by CSF-470 vaccine plus adjuvants, we evaluated, in an in vitro model, leukocyte migration, cytokine production, and monocyte phagocytosis of vaccine cells. Our results demonstrate that leukocytes recruitment, mostly from the innate immune system, is an early event after CSF-470 vaccine plus BCG plus GM-CSF interaction with immune cells, possibly explained by the high expression of CCL2/MCP-1 and other chemokines by vaccine cells. Early release of TNF-α and IL-1β pro-inflammatory cytokines and efficient tumor Ags phagocytosis by monocytes take place and would probably create a favorable context for Ag processing and presentation. Although the presence of the vaccine cells hampered cytokines production stimulated by BCG in a mechanism partially mediated by TGF-β and IL-10, still significant levels of TNF-α and IL-1β could be detected. Thus, BCG was required to induce local inflammation in the presence of CSF-470 vaccine cells.

Antitumor activity of T cells generated from lymph nodes draining the SEA-expressing murine B16 melanoma and secondarily activated with dendritic cells

The successful use of tumor-draining lymph nodes (TDLN) as a source of effector cells for cancer immunotherapy depends largely on the immunogenicity of the tumor drained by the lymph nodes as well as the methods for secondary in vitro T cell activation and expansion. We transferred the bacterial superantigen staphylococcal enterotoxin A (SEA) gene into B16 murine melanoma tumor cells, and used them to induce TDLN (SEA TDLN) in syngeneic hosts. Wild-type (wt) TDLN induced by parental B16 tumor was used as a control. In vitro, SEA TDLN cells proliferated more vigorously, produced more IFNγ and demonstrated higher CTL activity than wt TDLN cells when activated with anti-CD3/anti-CD28/IL-2. In vivo, SEA TDLN cells mediated tumor eradication more effectively than similarly activated wt TDLN cells (p<0.01). Furthermore, use of dendritic cells (DC) plus tumor antigen in vitro in addition to anti-CD3/anti-CD28/IL-2 stimulation further amplified the immune function and therapeutic efficacy of SEA TDLN cells. DC-stimulated SEA TDLN cells eliminated nearly 90% of the pulmonary metastasis in mice bearing established B16 melanoma micrometastases. These results indicate that enforced expression of superantigen SEA in poorly immunogenic tumor cells can enhance their immunogenicity as a vaccine in vivo. The combined use of genetically modified tumor cells as vaccine to induce TDLN followed by secondary stimulation using antigen-presenting cells and tumor antigen in a sequential immunization/activation procedure may represent a unique method to generate more potent effector T cells for adoptive immunotherapy of cancer.

Investigation of Mitomycin-C-treated Fibroblasts in 3-D Collagen Gel and Conditioned Medium for Keratinocyte Proliferation

Fibroblasts produce a spectrum of necessary growth factors essential for growth and proliferation of a variety of cell types. In this study, the paracrine effect of mitomycin-C-treated fibroblasts with various densities in collagen gel for keratinocyte proliferation was investigated from which an optimum cell density and optimum conditioned medium would be determined to expand keratinocyte without further differentiation for skin equivalent tissue engineering. The optimum cell density in collagen feeder gel for optimum collected medium preparation will be determined by checking the level of keratinocyte growth factor and granulocyte macrophage colony-stimulating factor in conventional medium. The results showed that the cell density of 1 x 10(5) cells/gel in the feeder gel is better to produce optimum collected medium. The conditioned medium is prepared by mixing together the optimum collected medium and molecular cellular and developmental biology (MCDB) 153 medium in different ratios for keratinocyte growth. The keratinocyte viability will be measured by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to determine the optimum conditioned medium. From the study, 67% conditioned medium was supposed as the better medium for keratinocyte proliferation. In this experiment, the optimum cell density in feeder gel to coculture with keratinocytes is also determined as 1 x 10(5) cells/gel. Keratin 10 (K10) and Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling stain will be used to check the cell differentiation and apoptosis, respectively. The results suggest that keratinocytes should not be cultured in postconfluent conditions due to undesired apoptosis and differentiation. The result of cell viability from passages to passages shows that the optimum feeder gel plays a more important role to the keratinocyte proliferation than that of optimum conditioned medium. Keratinocytes cultured with optimum feeder gel in 67% conditioned medium could effectively promote proliferation, inhibit apoptosis, and prevent differentiation. The combination of conditioned media and feeder gel to culture keratinocytes without external supplements can provide an inexpensive way for keratinocyte proliferation and construct an environment for real-time communication between the two cells. The results conclude that keratinocyte cultivation in feeder gel with modified medium should be feasible in the production of high quality keratinocytes for skin equivalents preparation.

Phase II trial of autologous tumor vaccination, anti-CD3-activated vaccine-primed lymphocytes, and interleukin-2 in stage IV renal cell cancer

PURPOSE

Previous preclinical and clinical studies have demonstrated that autologous tumor vaccines can induce relatively specific tumor-reactive T cells in draining lymph nodes. The adoptive transfer of these cells can result in tumor regression.

PATIENTS AND METHODS

Patients with stage IV renal cell cancer (RCC) were vaccinated with irradiated autologous tumor cells admixed with Calmette-Guérin bacillus. Approximately 7 days later, vaccine-primed lymph nodes (VPLNs) were harvested and the lymphoid cells secondarily activated with anti-CD3 monoclonal antibody and expanded in interleukin 2 (IL-2). The activated cells were subsequently infused intravenously along with the concomitant administration of bolus IL-2 (360,000 U/kg intravenously x 15 doses).

RESULTS

Thirty-nine patients were entered onto the study, of whom 34 completed an initial course of cell therapy consisting of a mean (SEM) number of 4.3 (2.2) x 10(10) VPLN cells. Among subjects who received cell therapy, there were nine responses (four complete responses [CRs] and five partial responses [PRs]), for an overall response rate of 27%. The durations of the CRs were > 48, 45, > 35, and 12 months, and the durations of the PRs were > 63, 48, 15, 12, and 4 months. Cultured tumor cells were available to assess in vitro cytokine release of VPLN cells in 24 subjects. The median cytokine release ratio of interferon gamma (IFNgamma) to IL-10 for responders and nonresponders was 992 and 5, respectively, which was significantly different (P =.047).

CONCLUSION

The treatment protocol resulted in durable tumor responses in patients with advanced RCC. The ratio of IFNgamma and IL-10 cytokines released in response to tumor by the VPLN cells was a significant correlate with tumor response.

Immunologic monitoring of cancer vaccine therapy: results of a workshop sponsored by the Society for Biological Therapy

The Society for Biological Therapy held a Workshop last fall devoted to immune monitoring for cancer immunotherapy trials. Participants included members of the academic and pharmaceutical communities as well as the National Cancer Institute and the Food and Drug Administration. Discussion focused on the relative merits and appropriate use of various immune monitoring tools. Six breakout groups dealt with assays of T-cell function, serologic and proliferation assays to assess B cell and T helper cell activity, and enzyme-linked immunospot assay, tetramer, cytokine flow cytometry, and reverse transcription polymerase chain reaction assays of T-cell immunity. General conclusions included: (1) future vaccine studies should be designed to determine whether T-cell dysfunction (tumor-specific and nonspecific) correlated with clinical outcome; (2) tetramer-based assays yield quantitative but not functional data (3) enzyme-linked immunospot assays have the lowest limit of detection (4) cytokine flow cytometry have a higher limit of detection than enzyme-linked immunospot assay, but offer the advantages of speed and the ability to identify subsets of reactive cells; (5) antibody tests are simple and accurate and should be incorporated to a greater extent in monitoring plans; (6) proliferation assays are imprecise and should not be emphasized in future studies; (7) the reverse transcription polymerase chain reaction assay is a promising research approach that is not ready for widespread application; and (8)there is a critical need to validate these assays as surrogates for vaccine potency and clinical effect. Current data and opinion support the use of a functional assay like the enzyme-linked immunospot assay or cytokine flow cytometry in combination with a quantitative assay like tetramers for immune monitoring. At present, assays appear to be most useful as measures of vaccine potency. Careful immune monitoring in association with larger scale clinical trials ultimately may enable the correlation of monitoring results with clinical benefit.

Identification of a clinical-grade maturation factor for dendritic cells

Dendritic cells (DC) are essential for the generation of primary adaptive immune responses, but their full immunostimulatory capacities are only reached upon maturation. The authors compared several clinical-grade adjuvants of bacterial origin to determine their ability to induce phenotypic and functional maturation of monocyte-derived DC (Dendritophages, Dphi; IDM, Paris, France) differentiated with granulocyte-macrophage colony-stimulating factor and interleukin-13 in single-use cell processors (VacCell; IDM, Paris, France). Monophosphoryl lipid A, Mycobacterium bovis bacillus Calmette-Guerin, and Ribomunyl (Pierre Fabre Medicament, Boulogne, France) all appeared able to provide the signal necessary to initiate Dphi maturation. However, only Ribomunyl (Pierre Fabre Medicament) (containing membrane and ribosomal fractions from four bacterial strains) allowed the authors to obtain a significant enhancement of allostimulatory abilities and cytokine production by Dphi in the absence of active cellular infection. Addition of interferon-gamma (IFN-gamma) to Ribomunyl resulted in more pronounced upregulation of CD83, major histocompatibility complex class I, and B7 molecules by Dphi. Moreover, the IFN-gamma addition modulated their cytokine secretion, allowing higher levels of bioactive interleukin-12 concomitant with lower levels of interleukin-10. In kinetic studies, Dphi contact with Ribomunyl and IFN-gamma for 6 hours was sufficient to trigger a maturation process that completed spontaneously. Thus, Ribomunyl in association with IFN-gamma represents a suitable agent for the ex vivo production of mature monocyte-derived DC that can be used as cellular vaccines to promote a potent type I immune response.

Keratinocyte-derived granulocyte-macrophage colony stimulating factor accelerates wound healing: Stimulation of keratinocyte proliferation, granulation tissue formation, and vascularization

Chronic, nonhealing wounds represent a major clinical challenge to practically all disciplines in modern medicine including dermatology, oncology, surgery, and hematology. In skin wounds, granulocyte-macrophage colony stimulating factor (GM-CSF) is secreted by keratinocytes shortly after injury and mediates epidermal cell proliferation in an autocrine manner. Many other cells involved in wound healing including macrophages, lymphocytes, fibroblasts, endothelial cells, and dendritic cells synthesize GM-CSF and/or are targets of this cytokine. Therefore, GM-CSF is a pleiotropic cytokine evoking complex processes during wound repair. Despite this complexity and the scarcity of mechanistic understanding GM-CSF has been employed in trials of clinical treatment of skin wounds with some success. In this study, we evaluated a transgenic mouse model in order to analyze the effects of an excess of keratinocyte-derived GM-CSF on excisional wound healing in the skin. Transgenic mice constitutively overexpressing GM-CSF in the basal layer of the epidermis displayed accelerated reepithelialization of full-thickness skin wounds. In the early stages of wound repair, transgenic mice exhibited significantly higher numbers of proliferating keratinocytes at the wound edges and increased formation of granulation tissue with enhanced neovascularization. As a potential mechanism of these beneficial changes, we identified the differential temporal regulation of cytokines such as transforming growth factor-beta, a known angiogenetic factor, interferon-gamma, a proinflammatory cytokine, and interleukin 6, an essential factor for reepithelialization, in transgenic mice versus controls. We propose that the beneficial effects observed in GM-CSF transgenics are due not only to direct GM-CSF action but in addition to indirect processes via the induction of secondary cytokines.

Lysine: Is it worth more?

Lysine, an essential cationic amino acid, has a positively charged R group. The structure of lysine is given as (H(3)N(+)-)CH(-COO(-))-CH(2)-CH(2)-CH(2)-CH(2)-N(+)H(3).While the anabolic role(s) of the molecule has been in focus for quite a few decades now, its biological properties, e.g. role in cellular proliferation in vitro (both anchorage dependent and anchorage independent) and in vivo, its ability to induce strong inflammatory and immune responses - both humoral and cell mediated, its role in augmented healing of all types of wounds in animal models as well as in human subjects (both acute and chronic), as well as its role in inducing extensive angiogenic responses, have never received reasonable attention so far. In the current brief and indicative review (rather than exhaustive reviews of each area), we intend to bring these biological properties of the molecule to focus while discussing a few other interesting aspects - lysine as a food preservative as well as its possible role(s) in immune therapy. While the areas look extremely divergent, we propose a common denominator in the form of a possible molecular mechanism of action of the molecule in all these diverse situations.

Innovations and strategies for the development of anticancer vaccines

In 1893, William Coley reported the spontaneous regression of a soft tissue sarcoma in several patients suffering from acute bacterial infections. Although this observation occurred over a century ago, the concept of anticancer vaccines and the immunotherapy of cancer has only recently seemed plausible. A myriad of specific and non-specific immunostimulatory approaches have been tested throughout the years with only a modicum of success. Most of these approaches were doomed from the outset since they were based on false or inadequate knowledge of tumour immunology. Recent advances in our understanding, most notably the identification of genes encoding for cancer regression antigens, currently permit investigators to pursue a more cogent strategy to develop novel and specific anticancer vaccine approaches. Several of these approaches are currently being tested in clinical trials and have already yielded exciting results. However, a number of immunologic and host obstacles to the successful application of anticancer vaccines remain. This editorial will provide an update on the clinical status of anticancer vaccines and review areas of promising research initiatives.