Whole-cell Tumor Vaccine Research Articles

Photodynamic Therapy Derived Personalized Whole Cell Tumor Vaccine Prevents Postsurgery Tumor Recurrence and Metastasis.

In order to avoid the time-consuming and laborious identification of tumor-specific antigens (TSAs) during the traditional vaccine fabrication process, a versatile photodynamic therapy (PDT)-based method is developed to construct a whole-tumor antigen tumor vaccine (TV) from surgically resected tumor tissues for personalized immunotherapy. Mucoadhesive nanoparticles containing small-molecular photosensitizer are fabricated and directly co-incubated with suspended tumor cells obtained after cytoreduction surgery. After irradiation with a 405nm laser, potent immunogenic cell death of cancer cells could be induced. Along with the release of TSAs, the as-prepared TV could activate safe and robust tumor-specific immune responses, leading to efficient suppression of postsurgery tumor recurrence and metastasis. The as-prepared TV cannot only be applied alone through various administration routes but also synergize with immunoadjuvant, chemotherapeutics, and immune checkpoint blockers to exert more potent immune responses. This work provides an alternative way to promote the clinical translation of PDT, which is generally restricted by the limited penetration of light. Moreover, the versatile strategy of vaccine fabrication also facilitates the clinical application of personalized whole-cell tumor vaccines.

Introduction of an Ultraviolet C-Irradiated 4T1 Murine Breast Cancer Whole-Cell Vaccine Model.

The advent of immunotherapy has revolutionized cancer treatments. However, the application of immune checkpoint inhibitors may entail severe side effects, with the risk of therapeutic resistance. The generation of chimeric antigen receptor (CAR) T-cells or CAR-NK cells requires specialized molecular laboratories, is costly, and is difficult to adapt to the rapidly growing number of cancer patients. To provide a simpler but effective immune therapy, a whole-cell tumor vaccine protocol was established based on ultraviolet C (UCV)-irradiated 4T1 triple-negative breast cancer cells. The apoptosis of tumor cells after UVC irradiation was verified using resazurin and Annexin V/propidium iodide flow cytometric assays. Protective immunity was achieved in immunized BALB/c mice, showing partial remission. Adoptive transfer of splenocytes or plasma from the mice in remission showed a protective effect in the naive BALB/c mice that received a living 4T1 tumor cell injection. 4T1-specific IgG antibodies were recorded in the plasma of the mice following immunization with the whole-cell vaccine. Interleukin-2 (IL-2) and oligonucleotide 2006 (ODN2006) adjuvants were used for the transfer of splenocytes from C57BL/6 mice into cyclophosphamide-treated BALB/c mice, resulting in prolonged survival, reduced tumor growth, and remission in 33% of the cases, without the development of the graft-versus-host disease. Our approach offers a simple, cost-effective whole-cell vaccine protocol that can be administered to immunocompetent healthy organisms. The plasma or the adoptive transfer of HLA-matching immunized donor-derived leukocytes could be used as an immune cell therapy for cancer patients.

Arsenic trioxide elicits prophylactic and therapeutic immune responses against solid tumors by inducing necroptosis and ferroptosis.

Boosting tumor immunosurveillance with vaccines has been proven to be a feasible and cost-effective strategy to fight cancer. Although major breakthroughs have been achieved in preventative tumor vaccines targeting oncogenic viruses, limited advances have been made in curative vaccines for virus-irrelevant malignancies. Accumulating evidence suggests that preconditioning tumor cells with certain cytotoxic drugs can generate whole-cell tumor vaccines with strong prophylactic activities. However, the immunogenicity of these vaccines is not sufficient to restrain the outgrowth of existing tumors. In this study, we identified arsenic trioxide (ATO) as a wide-spectrum cytotoxic and highly immunogenic drug through multiparameter screening. ATO preconditioning could generate whole-cell tumor vaccines with potent antineoplastic effects in both prophylactic and therapeutic settings. The tumor-preventive or tumor-suppressive benefits of these vaccines relied on CD8+ T cells and type I and II interferon signaling and could be linked to the release of immunostimulatory danger molecules. Unexpectedly, following ATO-induced oxidative stress, multiple cell death pathways were activated, including autophagy, apoptosis, necroptosis, and ferroptosis. CRISPR‒Cas9-mediated knockout of cell death executors revealed that the absence of Rip3, Mlkl, or Acsl4 largely abolished the efficacy of ATO-based prophylactic and therapeutic cancer vaccines. This therapeutic failure could be rescued by coadministration of danger molecule analogs. In addition, PD-1 blockade synergistically improved the therapeutic efficacy of ATO-based cancer vaccines by augmenting local IFN-γ production.

Single-cell analyses reveal the therapeutic effects of ATHENA and its mechanism in a rhabdomyosarcoma patient.

Whole-cell tumor vaccines tend to suffer from low immunogenicity. Our previous study showed that irradiated lung cancer cell vaccines in mouse models enhance antitumor efficacy by eliciting an intensive T cells response and improving immunogenicity. Based on these findings, we developed an improved whole-cell tumor vaccine, Autologous Tumor Holo antigEn immuNe Activation (ATHENA). In this study, we report the successful treatment of a 6-year-old male diagnosed with meningeal rhabdomyosarcoma with pulmonary and liver metastases using ATHENA. After 6 cycles of therapy, PET/CT showed the therapeutic efficacy of ATHENA. We profiled the immune response by single-cell RNA sequencing (scRNA-seq). Flow cytometry analysis was implemented to validate the status transitions of CD8+ T cells. In CD8+ T cells, the exhausted status was weakened after treatment. The exhausted CD4+ T cells shifted towards the central memory phenotype after the treatment. Breg cells were converted to Plasma or Follicular B cells. Survival analysis for pan-cancer and transcription factor analysis indicated that such T cell and B cell transitions represent the recovery of antitumoral adaptive immune response. We validated that the proportion of CD279+CD8+ T cells were reduced and the expression of CD44 molecule was upregulated by flow cytometry assay. Such studies not only show that ATHENA therapy may be a promising alternative treatment for tumor patients but provide a novel idea to analyses the mechanisms of rare cases or personalized cancer treatment.

Whole-cell tumor vaccines desialylated to uncover tumor antigenic Gal/GalNAc epitopes elicit anti-tumor immunity

BackgroundAberrant sialoglycans on the surface of tumor cells shield potential tumor antigen epitopes, escape recognition, and suppress activation of immunocytes. α2,3/α2,6Gal- and α2,6GalNAc (Gal/GalNAc)-linked sialic acid residues of sialoglycans could affect macrophage galactose-type lectins (MGL) mediated-antigen uptake and presentation and promote sialic acid-binding immunoglobulin-like lectins (Siglecs) mediated-immunosuppression. Desialylating sialoglycans on tumor cells could present tumor antigens with Gal/GalNAc residues and overcome glyco-immune checkpoints. Thus, we explored whether vaccination with desialylated whole-cell tumor vaccines (DWCTVs) triggers anti-tumor immunity in ovarian cancer (OC).MethodsSialic acid (Sia) and Gal/GalNAc residues on OC A2780, OVCAR3, and ID8 cells treated with α2-3 neuraminidase (α2-3NA) and α2-6NA, and Sigec-9 or Siglec-E and MGL on DCs pulsed with desialylated OC cells were identified using flow cytometry (FCM); RT-qPCR determined IFNG expression of T cells, TRBV was sequenced using Sanger sequencing and cytotoxicity of αβ T cells was measured with LDH assay; Anti-tumor immunity in vivo was validated via vaccination with desialylated whole-cell ID8 vaccine (ID8 DWCTVs).ResultsGal/GalNAc but not Sia residues were significantly increased in the desialylated OC cells. α2-3NA-modified DWCTV increased MGL but decreased Siglec-9 or Siglec E expression on DCs. MGLbright/Siglec-9dim DCs significantly up-regulated IFNG expression and CD4/CD8 ratio of T cells and diversified the TCR repertoire of αβ T-cells that showed enhanced cytotoxic activity. Vaccination with α2-3NA-modified ID8 DWCTVs increased MGLbright/Siglec-Edim DCs in draining lymph nodes, limited tumor growth, and extended survival in tumor-challenged mice.ConclusionDesialylated tumor cell vaccine could promote anti-tumor immunity and provide a strategy for OC immunotherapy in a clinical setting.

Combined Stereotactic Ablative Radiotherapy and Fibroblast Activation Protein Based Whole Cell Tumor Vaccine Synergize to Suppress Tumor Growth and Metastasis

Cancer-associated fibroblasts (CAFs), which occupy a major portion of the TME, play an important role in tumor growth, immunosuppression, treatment resistance. Our studies found that fibroblast activation protein α (FAPα) based whole cell tumor vaccine (WCTV) can induce a cross-immune response to produce specific neutralizing antibodies and CTL effects to kill tumor cells and CAFs. However, the therapeutic efficacy of vaccination is limited. Recent studies have revealed that stereotactic ablation radiotherapy (SABR) also elicit systemic antitumor immunity, which makes it an ideal partner for immunotherapy. The goal of this study was to examine synergistic effect of SABR and FAP-based WCTV.We produced FAPα-based WCTV by infecting tumor cells with lentiviral vector pCDH encoding FAPα, and then inactivating them with radiation (100Gy) for immunotherapy in vivo. To investigate the optimal protocol, we compared different SABR schemes and sequence of the combination of irradiation and FAPα- based WCTV in mouse LLC Lewis lung cancer model. Subsequently, we tested whether the combination protocol would result in enhanced anti-tumor activity and antifibrotic effect in mouse 4T1 breast cancer and CT26 colon cancer models. Furthermore, we analyzed the impact of treatment on cellular immunophenotypic characterization in TME via immunohistochemical staining and flow cytometry.We demonstrated that the therapeutic effect of SABR combined with FAPα-based WCTV is better than radiotherapy or vaccination alone. We identified the optimal dose scheme of SABR synergistically with FAPα- based WCTV is a single dose of 8Gy × 3 times, and the best treatment sequence is radiotherapy within one week after the first vaccination (three times in total). The optimal combination protocol also resulted in enhanced anti-tumor activity and antifibrotic effect against 4T1 breast cancer and CT26 colon cancer, and inhibited lung metastasis in breast cancer. No adverse effects were found based on gross measures of health. Importantly, collagen type I and FAPα expression in tumor tissue was significantly lower in SABR+ Vaccine treated mice than in control mice. SABR combined with FAPα-based WCTV reduced microvascular and lymphatic invasion, allowed polarization of tumor-associated macrophages to the M1-like phenotype. The relative percentage of M2 macrophages, MDSCs, and Tregs significantly decreased in the peripheral blood and lymph nodes. By contrast, CD8+ T lymphocytes especially activated cells increased.Our findings indicate that combined FAPα-based WCTV and SABR synergize to suppress tumor growth and metastasis via activating the systemic anti-tumor immune response, attenuating CAFs-mediated immunosuppression, interstitial fibrosis and treatment resistance. This novel combination of radio-immunotherapy may add a new perspective to cancer treatments.

Optimization of Whole Tumor Cell Vaccines by Interaction with Phagocytic Receptors.

The principal event in the function of whole-cell cancer vaccines is the ingestion of vaccine-delivered tumor antigen-containing material, which is performed by the patient’s antigen-presenting cells (APCs) through the employment of their phagocytic receptors. The goal of the present study was to identify the phagocytic receptors critical for the therapeutic efficacy of whole-cell cancer vaccines. The model of photodynamic therapy (PDT)-generated vaccines based on mouse SCCVII tumors was utilized, with in vitro expanded SCCVII cells treated by PDT serving as the vaccine material used for treating mice bearing established SCCVII tumors. The therapeutic impact, monitored as delayed progression of vaccinated tumors, was almost completely eliminated when antibodies specifically blocking the activity of LOX-1 scavenger receptor were administered to mice 30 min before vaccination. Similar, but much less pronounced, impacts were found with antibodies neutralizing the activity of CR3/CR4 receptors recognizing complement-opsonized vaccine cells, and with those blocking activating Fcγ receptors that recognized IgG antibody-based opsonins. A strikingly contrary action, a greatly enhanced tumor control by the vaccine, was found by blocking immune inhibitory receptor, FcγRIIB. The reported findings establish, therefore, an attractive strategy that can be effectively exploited for potent therapeutic enhancement of PDT-generated (and probably other) whole-cell tumor vaccines.

Synergistic Effect Of Stereotactic Ablative Radiotherapy And Immunotherapy With A Xenogeneic Fibroblast Activation Protein-Based Whole Cell Tumor Vaccine

Immunotherapies has revolutionized the treatment approach of patients with metastatic cancer, although response rates to such therapies when given alone are disappointingly limited in the majority. Stereotactic ablative radiotherapy (SABR) increases immunogenic cell death, boosts priming of APCs, activates effector T-cell responses, and serves as an ideal partner of immunotherapy. Accounting for a large proportion of cells in the tumor microenvironment (TME), cancer-associated fibroblasts (CAFs), along with their products such as fibroblast activation protein-α (FAPα), greatly affect tumor development and treatment resistance, which make them promising targets for immunotherapy. Therefore, the application of immunotherapy targeting CAFs combined with SABR may have a synergistic effect. We previously reported a xenogeneic FAPα-based whole cell tumor vaccine (WCTV) enhance specific antitumor responses to fight cancer cells and CAFs. This study aimed to test the efficacy and safety of SABR in combination with xenogeneic FAPα-based WCTV. In the present study, we firstly compare the different radiation schemes with a same biologically effective dose, the timing and sequence of the association of irradiation and FAPα-based WCTV in mouse LLC Lewis lung cancer model to investigate the optimal protocol. Mice were monitored for tumor growth, survival and gross measures of health. With the use of mouse H22 liver and 4T1 breast cancer models, we then tested the antitumor effect, safety and anti-fibrosis effect of the optimal combination protocol. The potential immune mechanisms were investigated through adoptive immunotherapy and 51Cr release assay. The distributions of the immune cells in the TME were detected by immunohistochemical staining and flow cytometry. SABR was dramatically more effective with 3x8Gy compared to 1×16.4Gy when associated with FAPα-based WCTV, and the best anti-tumor effect was observed in the group of mice started the vaccination on the 7th day after the last irradiation. No obvious side effects were detected following treatment. Tumor-infiltrating lymphocytes (TILs) ratio increased and products of CAF, such as FAPα, α-SMA and collagen I expression decreased in the tumor tissue. further investigation showed that the anti-tumor effect involves cellular and humoral immune responses. In the combination treatment group, T cells obtained from mice showed higher cytotoxicity against cancer cells and CAFs, and autoantibodies against FAPα were detected in the sera. These findings indicate combination of SABR and xenogeneic FAPα-based WCTV can weaken CAFs-mediated immune suppression, interstitial fibrosis and treatment tolerance to effectively inhabit tumor growth and reduce side effects. This study innovatively associates radiation therapy, anti-fibrosis therapy with immunotherapy, and provide new ideas for developing new treatment strategies for patients with multiple epithelial cancers.

Conjugation of TLR7 Agonist Combined with Demethylation Treatment Improves Whole-Cell Tumor Vaccine Potency in Acute Myeloid Leukemia.

Background: Acute myeloid leukemia (AML) is a malignant hematological disease with high refractory rate. Immune escape of AML cells is one of the underlying mechanisms mediating the relapse of the cancers. Various immunotherapies based on the 'patients' immune response to tumor cells have been developed to targeting the immune escape of AML cells, which lead to the minimal residual disease (MRD) after treatment. But the efficacy of those treatments or the combination of treatments remains unsatisfactory.Methods: A Toll-like receptor (TLR)-7 agonist SZU-106 was chemically synthesized. SZU-106 was conjugated to Decitabine (DAC), a demethylation agent, treated AML cells to construct tumor vaccine. The potency of the newly constructed AML cell vaccine, SZU-106-DAC-AML was tested in vitro and in vivo for the expression of tumor antigens and the activation level of immune responses.Results: Compared to the well characterized TLR7 agonist R848, SZU-106 has a comparable potency to activate TLR7 signaling pathway. SZU-106-DAC-AML, constructed by conjugating SZU-106 to DAC treated tumor cells, exhibited increased expression of tumor antigens, and enhanced the activation of DC cells and T cells in vitro and in vivo. The result of xenograft tumor model showed that SZU-106-DAC-AML tumor vaccine greatly inhibited tumor growth and prolonged animal survival.Conclusions: Conjugation of TLR7 agonist combined with up-regulation of tumor antigen expression improved the effectiveness of whole-cell tumor vaccine in AML.

Neutrophil infiltration and whole-cell vaccine elicited by N-dihydrogalactochitosan combined with NIR phototherapy to enhance antitumor immune response and T cell immune memory.

Melanoma is one of the deadliest malignancies with a high risk of relapse and metastasis. Long-term, tumor-specific, and systemic immunity induced by local intervention is ideal for personalized cancer therapy. Laser immunotherapy (LIT), a combination of local irradiation of laser and local administration of an immunostimulant, was developed to achieve such an immunity. Although LIT showed promising efficacy on tumors, its immunological mechanism is still not understood, especially its spatio-temporal dynamics.Methods: In this study, we investigated LIT-induced immunological responses using a 980-nm laser and a novel immunostimulant, N-dihydrogalactochitosan (GC). Then we followed the functions of key immune cells spatially and temporally using intravital imaging and immunological assays.Results: Immediately after LIT, GC induced a rapid infiltration of neutrophils which ingested most GC in tumors. The cytokines released to the serum peaked at 12 h after LIT. Laser irradiations produced photothermal effects to ablate the tumor, release damage-associated molecular patterns, and generate whole-cell tumor vaccines. LIT-treated tumor-bearing mice efficiently resisted the rechallenged tumor and prevented lung metastasis. Intravital imaging of tumor at rechallenging sites in LIT-treated mice revealed that the infiltration of tumor-infiltrating lymphocytes (TILs) increased with highly active motility. Half of TILs with arrest and confined movements indicated that they had long-time interactions with tumor cells. Furthermore, LIT has synergistic effect with checkpoint blockade to improve antitumor efficacy.Conclusion: Our research revealed the important role of LIT-induced neutrophil infiltration on the in situ whole-cell vaccine-elicited antitumor immune response and long-term T cell immune memory.

Whole-Cell Cancer Vaccines Induce Large Antibody Responses to Carbohydrates and Glycoproteins

Whole-cell cancer vaccines are a promising strategy for treating cancer, but the characteristics of a favorable immune response are not fully understood. New insights could enable development of better vaccines, discovery of new antigens, and identification of biomarkers of efficacy. Using glyco-antigen microarrays, we demonstrate that GVAX Pancreas (a granulocyte macrophage colony-stimulating factor-modified whole-cell tumor vaccine) induces large immunoglobulin G and immunoglobulin M responses to many antigens, including tumor-associated carbohydrates, blood group antigens, α-Gal, and bovine fetuin. Antibody responses to α-Gal, a glycan found in fetal bovine serum (FBS) used to produce the vaccine, correlated inversely with overall survival and appear to compete with productive responses to the vaccine. H1299 lysate vaccine, produced with FBS, also induced responses to α-Gal and fetuin but not K562-GM, which is produced in serum-free medium. Our results provide new potential biomarkers to evaluate productive/unproductive immune responses and suggest that removal/reduction of FBS could improve the efficacy of whole-cell vaccines.

Apoptotic Melanoma B16-F1 Cells Induced by Lidamycin Could Initiate the Antitumor Immune Response in BABL/c Mice.

In the process of tumor cell apoptosis induced by specific regents, calreticulin (CRT) was transferred from endoplasmic reticulum (ER) onto the cell membrane. These tumor cells, when used as the cellular vaccine to immunize experimental animals, could initiate effective antitumor immunoresponse against homologous tumor cells. This is referred to as immunogenic cell death. Lidamycin (LDM) is an enediyne antibiotic, which has extremely potent cytotoxicity to cancer cells. In this study, the mouse melanoma B16-F1 cancer cells were used to investigate the ability of LDM in promoting immunogenic cell death. Our data showed that LDM could induce apoptosis of B16-F1 cancer cells, accompanied by CRT translocation onto the cell membrane. These LDM-treated B16-F1 cells could be recognized and phagocytosed more efficiently by macrophage and dendritic cells. When the LDM-treated apoptotic B16-F1 cells were used as a whole-cell tumor vaccine to immune mice, the mice obtained resistance against rechallenged B16-F1 living cells. At the same time, the specific antitumor immune response was observed in these vaccinated mice. The splenocytes from the mice vaccinated with LDM-treated B16-F1 cells showed significantly enhanced NK lymphocyte activities and also faster growth rate and increased secretion of IFN-γ when encountering the cellular antigens from B16-F1 cells. All these results suggested that LDM could promote immunogenic cell death in B16-F1 cells, and these LDM-treated B16-F1 cells could be used as a sort of cell vaccine to initiate effective antitumor immunoresponse in mice.

A whole-cell tumor vaccine modified to express fibroblast activation protein induces antitumor immunity against both tumor cells and cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAFs) are common components of the tumor-suppressive microenvironment, and are a major determinant of the poor outcome of therapeutic vaccination. In this study, we modified tumor cells to express the fibroblast activation protein (FAP), which is highly expressed by CAFs, to potentially improve whole-cell tumor vaccines by targeting both tumor cells and CAFs. Tumor cells were transfected with murine FAP plasmids bearing the cationic lipid DOTAP. Its antitumor effects were investigated in three established tumor models. Vaccination with tumor cells expressing FAP eliminated solid tumors and tumors resulting from hematogenous dissemination. This antitumor immune response was mediated by CD8+ T cells. Additionally, we found that CAFs were significantly reduced within the tumors. Furthermore, this vaccine enhanced the infiltration of CD8+ T lymphocytes, and suppressed the accumulation of immunosuppressive cells in the tumor microenvironment. Our results indicated that the FAP-modified whole-cell tumor vaccine induced strong antitumor immunity against both tumor cells and CAFs and reversed the immunosuppressive effects of tumors by decreasing the recruitment of immunosuppressive cells and enhancing the recruitment of effector T cells. This conclusion may have important implications for the clinical use of genetically modified tumor cells as cancer vaccines.

In MCA-induced sarcoma models, booster vaccination with GM-CSF-secreting whole-cell tumor vaccines maintain or improve efficacy but may alter trafficking of tumor-specific T cells (VAC13P.1128)

Abstract Previously, we reported that while a single vaccination effectively generated therapeutic tumor-specific T cells for adoptive immunotherapy (AIT), repeated vaccination with the poorly immunogenic B16BL6 melanoma, modified to secrete GM-CSF, induced high levels of CD4+FoxP3+ T regulatory (Treg) cells and AIT with spleen cells was non-therapeutic. The effect could be overcome by transient depletion of CD4+ T cells, confirming the effect of Treg cells. Here experiments were performed to test whether this suppressive effect was observed in active-specific protection in 2 sarcoma models, MCA-304 and MCA-310. Mice were vaccinated once or thrice with either irradiated parental sarcoma or that sarcoma expressing GM-CSF. We did not observe significant changes in percentage or total count of splenic Treg cells under any conditions, however, tumor-specific IFN-γ release decreased in mice thrice vaccinated with GM-CSF-secreting tumors compared to parental (p < 0.001). Importantly, multiple vaccination offered tumor protection that was as good or better than single vaccination. In the most strongly immunogenic tumor, MCA-304, both single and triple vaccination with parental or GM-CSF-secreting tumors provided 100% protection. However, in the weakly immunogenic, MCA-310 sarcoma, multiple vaccinations improved effectiveness with the greatest effect seen with the GM-CSF-secreting MCA-310. Our results provide a rationale for the continued use of GM-CSF as a cancer vaccine adjuvant.

Paradoxical decrease in the capture and lymph node delivery of cancer vaccine antigen induced by a TLR4 agonist as visualized by dual-mode imaging.

Traditionally, cell-mediated immune responses to vaccination in animal models are evaluated by invasive techniques such as biopsy and organ extraction. We show here that by combining two noninvasive imaging technologies, MRI and bioluminescence imaging (BLI), we can visualize both the afferent and efferent arms of cellular events following vaccination longitudinally. To this end, we evaluated the immune response elicited by a novel Toll-like receptor 4 agonist vaccine adjuvant, glucopyranosyl lipid A (GLA), using a whole-cell tumor vaccine. After magnetovaccination, MRI was used to visualize antigen-presenting cell-mediated antigen capture and subsequent migration to draining lymph nodes (DLN). Paradoxically, we observed that the incorporation of GLA in the vaccine reduced these critical parameters of the afferent immune response. For the efferent arm, the magnitude of the ensuing antigen-specific T-cell response in DLN visualized using BLI correlated with antigen delivery to the DLN as measured by MRI. These findings were confirmed using flow cytometry. In spite of the GLA-associated reduction in antigen delivery to the DLN, however, the use of GLA as a vaccine adjuvant led to a massive proliferation of vaccine primed antigen-specific T cells in the spleen. This was accompanied by an enhanced tumor therapeutic effect of the vaccine. These findings suggest that GLA adjuvant changes the temporal and anatomical features of both the afferent and efferent arms of the vaccine response and illustrates the utility of quantitative noninvasive imaging as a tool for evaluating these parameters during vaccine optimization.

Interleukin‑15: a potent adjuvant enhancing the efficacy of an autologous whole‑cell tumor vaccine against Lewis lung carcinoma.

Lung cancer is a major cause of cancer‑associated mortality worldwide due to its limited response rate to current chemotherapy and radiation, thus immunotherapy is rapidly becoming the most promising approach. Although the highly specific tumor‑associated antigen of lung cancer has been found, autologous whole‑cell tumor vaccines remain indispensable in the development of therapeutic cancer vaccines. Interleukin (IL)‑15 is a T helper type 1 cytokine that has been demonstrated to have a marked antitumor immune response and the potential ability to reverse the host tolerance of tumor antigens in certain preclinical trials. In the present study, a cationic liposome encapsulating IL‑15 gene‑loaded plasmid acted as an adjuvant of an autologous whole‑cell tumor vaccine by subcutaneous injection. The combination immunotherapy resulted in significant inhibition of tumor growth without side effects in the preventive tumor inhibition and adoptive therapy study. Cytotoxic lymphocyte assay detection of the serum antigen and cytokines using an enzyme‑linked immunosorbent assay suggested that the IL‑15 gene can significantly improve the cellular immune response and humoral immune response provoked by autologous whole‑cell tumor vaccines. These results demonstrated that the IL‑15 gene was an effective adjuvant of autologous whole‑cell tumor vaccines against mouse lung cancer and may provide an attractive vaccine strategy for cancer immunotherapy.

Induction of dendritic cell maturation in the skin microenvironment by soluble factors derived from colon carcinoma

Autologous tumor cell-based vaccines provide a wide range of tumor antigens and personalized neo-epitopes based on individual tumors’ unique antigenic mutanome signatures. However, tumor-derived factors may hamper in situ maturation of dendritic cells (DC) and thus interfere with the generation of effective anti-tumor immunity. As the skin is a preferred site for tumor vaccine delivery, we investigated the influence of primary colon carcinoma-derived soluble factors on the maturation state of migrating DC in a human skin explant model. Primary tumor-derived supernatants (TDSN) enhanced the phenotypic maturation state of skin-emigrated DC, resulting in an increased T-cell stimulatory ability in an allogeneic mixed leukocyte response. In case of monocyte-derived DC a similar TDSN-induced maturation induction was found to entirely depend on cyclooxygenase (COX)-regulated prostaglandins. In contrast, the increase in skin-emigrated DC maturation was completely prostaglandin-independent, as evidenced by the inability of the COX inhibitor indomethacin to abrogate this TDSN-induced effect. Although TDSN conditioning affected a drop in IL-12p70 release by the skin-emigrated DC and induced a predominant Th17/Th22 transcriptional profile in subsequently stimulated T-cells, Th cell subset differentiation, as assessed by intracellular cytokine expression upon polyclonal priming and re-stimulation, was not affected. Comparative analysis of phenotypic and transcriptional profiles suggests that the observed maturational effects in skin-derived DC may have been induced by tumor-derived GM-CSF. In conclusion, soluble factors derived from whole-cell colon tumor vaccines will not negatively impact DC migration and maturation in human skin, but rather induce DC maturation that will facilitate the priming of a poly-functional Th cell response.

Cyclophosphamide in combination with tumor lysate and TLR9 ligand regresses murine neuroblastoma

Neuroblastoma is a pediatric cancer of neural crest origin that accounts for 12% of all pediatric cancer deaths. Despite improved survival in patients that receive standard care plus anti-GD2 immune therapy, there remains a 40% mortality rate in high-risk patients. This high mortality emphasizes the need for continued testing of immune-based therapies for the treatment of refractory neuroblastoma. Using a murine model, we previously observed a cell-mediated immune response resulting in elimination of established neuroblastoma when mice were given a whole-cell tumor vaccine expressing CD80, CD86, CD54 and CD137L. Given the anti-tumor efficacy of this immune-based therapy, we designed and tested a more clinically translatable protocol for the treatment of established neuroblastoma. In this study, unmodified tumor cell lysate and the TLR9 ligand, CpG-ODN 1826 (CpG), was given as immune therapy in combination with cyclophosphamide (CY). To establish tumor burden, mice were inoculated subcutaneously (s.c.) with 10E5 live neuroblastoma cells. Four and five days following tumor inoculation mice received 100 mg/kg intravenous cyclophosphamide. Nine 16, 23, and 30 days following tumor inoculation some mice received the tumor cell lysate and CpG immune therapy. When only CY was administered, all mice succumbed to tumor. When tumor lysate and CpG were added to the CY treatment protocol, tumors regressed and there was 60% survival. Immune cell analysis revealed an increase in activated mature (I-Ak+CD11c+) dendritic cells in the spleen and draining lymph nodes of mice that received CY, CpG and tumor lysate. We also found evidence of an adaptive immune response. Mice treated with CY, CpG and tumor lysate had an increase in the percentage of Ki67+ proliferating splenic CD4 and CD8 T cells. In addition, there was an increase in T effector memory (CD44hiCD62Llo) cells in the spleens of mice treated with Cy, lysate and CpG. Splenic T cells harvested from these mice produced interferon gamma (IFN-γ) when exposed to neuroblastoma tumor cells. Of great importance for clinical translation, when either autologous or allogeneic lysate was given in combination with CY and CpG, IFN-γ was produced in tumor-specific splenic CD8 T cells. Survival curves were similar regardless of administration of autologous or allogeneic tumor lysate. We are continuing to explore the treatment-related immune mechanisms that promote tumor regression with hope for clinical translation of this protocol.

Nanoparticles-based multi-adjuvant whole cell tumor vaccine for cancer immunotherapy

Whole cell tumor vaccine (WCTV), as a potential treatment modality, elicits limited immune responses because of the poor immunogenicity. To address this issue, researchers have attempted to transduce a cytokine adjuvant into tumor cells, but these single-adjuvant WCTVs curtail the high expectations. In present study, we constructed a multi-adjuvant WCTV based on the nanoparticles modified with cell penetrating peptide, which could facilitate the transportation of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 2 (IL-2) into tumor cells. After inactivation, as-designed multi-adjuvant WCTV exhibited programmed promotions on DC recruitment, antigen presentation, and T-cell activation. In vivo evaluations demonstrated the satisfactory effects on tumor growth suppression, metastasis inhibition, and recurrence prevention. Therefore, the nanoparticles-based multi-adjuvant WCTV may serve as a high-performance treatment for anti-tumor immunotherapy.

A novel iNKT cell-mediated vaccine maneuver induces potent long-lasting anti-tumor immunity for advanced prostate cancer by boosting CD8+T cell memory and function (53.24)

Abstract iNKT cells have considerable therapeutic promise in cancer, but so far this has not been fully realized. At issue has been delivering iNKT ligand and tumor Ag to the same APC for optimal processing and presentation. Also, although tumor-infiltrating APCs express CD1d in both prostate cancer (PCa) models and patients, tumor induced tolerance and suppression leads to defective iNKT activation. Whole-cell tumor vaccines represent a promising treatment approach and prevent tumor progression in multiple models of cancer. Here, we use an optimized approach consisting of alpha-galactosylceramide (aGalCer) and the GM-CSF-based PCa vaccine, ‘GVax’ combined with IL-12. This approach was capable of breaking tumor-induced tolerance and causing dramatic and substantial tumor regression and survival in large advanced prostate tumors in TRAMP mice. Remarkably, 10/12 vaccinated >9 month old mice rejected tumors, 'breaking tolerance', even at this late stage of tumor growth. The vaccine induced strong immune responses capable of reversing INKT defects in tumor-bearing mice as well as in patient iNKT in vitro. Both IL-12 and aGalCer were crucial for this response. Vaccinated mice had higher levels and activation of tumor-specific CD8 T, CD4 T and iNKT cells, and greater memory CD8 T cell expansion capable of producing the effector cytokines IFN-γ and TNF-α in response to tumor. These studies shed light on how whole cell vaccines targeting iNKTs can be utilized in PCa immunotherapy.