The large scale generation of dendritic cells for the immunization of patients with non-small cell lung cancer (NSCLC)

Characteristics of tumor microenvironment and novel immunotherapeutic strategies for non-small cell lung cancer

Immune checkpoint inhibitor-based immunotherapy has revolutionized the treatment approach of non-small cell lung cancer (NSCLC). Monoclonal antibodies against programmed cell death-1 (PD-1) and PD-ligand 1 (PD-L1) are widely used in clinical practice, but other antibodies that can circumvent innate and acquired resistance are bound to undergo preclinical and clinical studies. However, tumor cells can develop and facilitate the tolerogenic nature of the tumor microenvironment (TME), resulting in tumor progression. Therefore, the immune escape mechanisms exploited by growing lung cancer involve a fine interplay between all actors in the TME. A better understanding of the molecular biology of lung cancer and the cellular/molecular mechanisms involved in the crosstalk between lung cancer cells and immune cells in the TME could identify novel therapeutic weapons in the old war against lung cancer. This article discusses the role of TME in the progression of lung cancer and pinpoints possible advances and challenges of immunotherapy for NSCLC.

Dendritic Cell-Based Immunotherapy in Lung Cancer

Lung cancer remains the leading cause of cancer-related death worldwide. The advent of immune checkpoint inhibitors has led to a paradigm shift in the treatment of metastatic non-small cell and small cell lung cancer. However, despite prolonged overall survival, only a minority of the patients derive clinical benefit from these treatments suggesting that the full anti-tumoral potential of the immune system is not being harnessed yet. One way to overcome this problem is to combine immune checkpoint blockade with different strategies aimed at inducing or restoring cellular immunity in a tumor-specific, robust, and durable way. Owing to their unique capacity to initiate and regulate T cell responses, dendritic cells have been extensively explored as tools for immunotherapy in many tumors, including lung cancer. In this review, we provide an update on the nearly twenty years of experience with dendritic cell-based immunotherapy in lung cancer. We summarize the main results from the early phase trials and give an overview of the future perspectives within this field.

Detection of tumor antigens and tumor-antigen specific T cells in NSCLC patients: Correlation of the quality of T cell responses with NSCLC subtype

Allogeneic cancer cell lines serve as universal source of tumor-associated antigens in cancer vaccines. Immunogenic high hydrostatic pressure-killed cancer cells derived from cell lines can be used for the generation of dendritic cell (DC)-based active cellular immunotherapy of non-small cell lung cancer (NSCLC). We investigated the expression of 12 known NSCLC tumor-associated antigens (TAA) (CEA, MAGE-A1, MAGE-A3, MAGE-A4, PRAME, hTERT, HER2, MUC1, Survivin, STEAP1, SOX2 and NY-ESO-1) in 6 NSCLC cell lines as candidates for the generation of DC-based lung cancer vaccine. We showed that the selected antigenic profile of these cell lines overlaps to various degrees with that of primary NSCLC tumors (n = 52), indicating that 4 out of 6 NSCLC cell lines would be suitable for DC-based vaccine generation. We further investigated the presence of TAA-specific T cells in blood of NSCLC patients (n = 32) using commercially available peptide mixes in an in vitro stimulation assay. IFN-γ⁺CD8⁺ and IFN-γ⁺CD4⁺ T cell responses to all antigens were detected in NSCLC patients. Interestingly, despite higher TAA expression in squamous cell carcinoma (SCC) the responsiveness of patients' T cells to stimulation was significantly lower in SCC patients than in adenocarcinoma (AC) patients. This suggests qualitative differences in T cell functionality between NSCLC subtypes. Based on this study, and in order to maximize the amount of treatable patients, we selected a mix of H520 and H522 NSCLC cell lines for DC-based vaccine preparation. We also established a minimal panel of antigenic peptide mixes (CEA, hTERT, PRAME, HER2) for immunomonitoring of T cell responses during the DC-based lung cancer immunotherapy in Phase I lung cancer clinical trial (NCT02470468).

Cellular immunotherapy of cancer: an overview and future directions

The clinical success of checkpoint inhibitors has led to a renaissance of interest in cancer immunotherapies. In particular, the possibility of ex vivo expanding autologous lymphocytes that specifically recognize tumor cells has attracted much research and clinical trial interest. In this review, we discuss the historical background of tumor immunotherapy using cell-based approaches, and provide some rationale for overcoming current barriers to success of autologous immunotherapy. An overview of adoptive transfer of lymphocytes, tumor infiltrating lymphocytes and dendritic cell therapies is provided. We conclude with discussing the possibility of gene-manipulating immune cells in order to augment therapeutic activity, including silencing of the immune-suppressive zinc finger orphan nuclear receptor, NR2F6, as an attractive means of overcoming tumor-associated immune suppression.

Generation of dendritic cell-based vaccine using high hydrostatic pressure for non-small cell lung cancer immunotherapy

High hydrostatic pressure (HHP) induces immunogenic death of tumor cells which confer protective anti-tumor immunity in vivo. Moreover, DC pulsed with HHP-treated tumor cells induced therapeutic effect in mouse cancer model. In this study, we tested the immunogenicity, stability and T cell stimulatory activity of human monocyte-derived dendritic cell (DC)-based HHP lung cancer vaccine generated in GMP compliant serum free medium using HHP 250 MPa. DC pulsed with HHP-killed lung cancer cells and poly(I:C) enhanced DC maturation, chemotactic migration and production of pro-inflammatory cytokines after 24h. Moreover, DC-based HHP lung cancer vaccine showed functional plasticity after transfer into serum-containing media and stimulation with LPS or CD40L after additional 24h. LPS and CD40L stimulation further differentially enhanced the expression of costimulatory molecules and production of IL-12p70. DC-based HHP lung cancer vaccine decreased the number of CD4+CD25+Foxp3+ T regulatory cells and stimulated IFN-γ-producing tumor antigen-specific CD4+ and CD8+ T cells from non-small cell lung cancer (NSCLC) patients. Tumor antigen specific CD8+ and CD4+ T cell responses were detected in NSCLC patient's against a selected tumor antigens expressed by lung cancer cell lines used for the vaccine generation. We also showed for the first time that protein antigen from HHP-killed lung cancer cells is processed and presented by DC to CD8+ T cells. Our results represent important preclinical data for ongoing NSCLC Phase I/II clinical trial using DC-based active cellular immunotherapy (DCVAC/LuCa) in combination with chemotherapy and immune enhancers.

Selective colorectal cancer cell lysates enhance the immune function of mature dendritic cells in vitro

The aim of the present study was to determine the most effective antigen with which to mature dendritic cells (DCs). The immune function of DCs loaded with lysates from three different colorectal cancer cell lines was compared. DCs were induced using granulocyte macrophage colony‑stimulating factor, interleukin (IL)‑4 and tumor necrosis factor-α from the peripheral blood mononuclear cells of patients with colorectal cancer, and loaded with lysates from Colo320, SW480 and SW620 colorectal cancer cell lines, respectively. Autogenous T cells were co‑cultured with mature DCs. Surface markers and the secretory function of mature DCs and stimulated T cells were then analyzed. MTT assays were used to evaluate the killing capacity of autogenous cytotoxic T lymphocytes (CTLs). Compared with control, cluster of differentiation (CD)1a, CD83 and CD86, and human leukocyte antigen‑DR expression levels were significantly higher in DCs matured using cancer cell lysates. In addition, IL‑12 secretion levels were elevated. Autogenous T cells stimulated with DCs that were matured using cancer cell lysates showed a higher proliferation capacity, increased interferon-γ secretion levels and stronger cytotoxic abilities compared with control cells. Among the three cell lines, SW480 lysates were most effective at promoting DC and T cell function. The results showed that SW480 lysates are more efficient than Colo320 and SW620 lysates in inducing DC immune function and activating the antitumor function of autogenous T cells.

Pemetrexed plus dendritic cells as second-line treatment for patients with stage IIIB/IV non-small cell lung cancer who had treatment with TKI

The aim of this study was to determine the efficacy and toxicity of pemetrexed plus dendritic cells (DCs) in patients suffering from stage IIIB or IV lung adenocarcinoma, who had undergone maintenance treatment with gefitinib or erlotinib. Patients who had failed gefitinib or erlotinib maintenance treatment had ECOG performance statuses ranging from 0 to 2.27 patients received pemetrexed plus DCs as second-line treatment. Dosage: 500 mg/m(2) pemetrexed was administered on day 1 of a 21-day cycle. DCs were given for one cycle of 21 days. Three patients (11.1 %) experienced a partial response and 14 patients (51.9 %) showed stable disease. Ten patients (37.0 %) had progressive disease. The median time to progression-free survival (PFS) was 4.8 months [95 % confidence interval (CI) 4.4-5.2], and the median overall survival was 10.7 months (95 % CI 10.3-11.2). In the subgroup analysis, PFS had a significant difference between the low ratio of CD4/CD8 and normal ratio of CD4/CD8, with 4.5 months (95 % CI 4.2-4.9) and 5.0 months (95 % CI 4.5-5.7), (Log Rank = 0.039), respectively. No one patient experienced grade 4 toxicity. A regimen of pemetrexed combined with DCs is marginally effective and well tolerated in patients with stage IIIB or IV lung adenocarcinoma who had received gefitinib or erlotinib first-line treatment.

Clinical trials targeting lung cancer with active immunotherapy: the scope of vaccines

Successful active immunotherapy is expected to be specific and nontoxic. Until now, the success of immunotherapy in cancer has been sporadic and unpredictable. This has been attributable in part to the lack of a full understanding of the mechanistic underpinnings of immune regulation. Furthermore, the lack of systematic success of immunotherapy, as argued in this review, stems from failing to effectively target tumors such as non-small cell lung cancer. In this review, the rationale and design for induction of immunity to non-small cell lung cancer and clinical trials of the most important lung cancer vaccines in development are discussed.

Allogeneic tumor cell vaccines: the promise and limitations in clinical trials

The high mortality rate associated with cancer and its resistance to conventional treatments such as radiation and chemotherapy has led to the investigation of a variety of anti-cancer immunotherapies. The development of novel immunotherapies has been bolstered by the discovery of tumor-associated antigens (TAAs), through gene sequencing and proteomics. One such immunotherapy employs established allogeneic human cancer cell lines to induce antitumor immunity in patients through TAA presentation. Allogeneic cancer immunotherapies are desirable in a clinical setting due to their ease of production and availability. This review aims to summarize clinical trials of allogeneic tumor immunotherapies in various cancer types. To date, clinical trials have shown limited success due potentially to extensive degrees of inter- and intra-tumoral heterogeneity found among cancer patients. However, these clinical results provide guidance for the rational design and creation of more effective allogeneic tumor immunotherapies for use as monotherapies or in combination with other therapies.

Generation and characterization of non-small-cell lung cancer cell lines and clones for use in the study of immunotherapy

The in vitro study of cancer has been made easier by the use of stable tumor cell (TC) lines derived from patients to study antigen expression, immunogenicity, and response to both experimental and conventional therapeutic agents. However, the routine generation of these cell lines in some tumor histologies such as non-small-cell lung cancer (NSCLC) is difficult. In many cases, colonies of TCs do not survive, most likely due to a lack of critical growth factors in cell culture medium. Other times, TC colonies are overgrown by fibroblasts, which appear to have less stringent growth requirements. In some cases, cultures are overgrown by bacteria or mold contained in the biopsy arriving from the surgical or pathology suite. This study presents the characteristics of three new NSCLC cell lines and associated autologous clones generated from both adenocarcinoma and squamous cell carcinoma tissue. Different culture media and variable techniques were used to generate these stable TC lines. Limiting dilution analysis resulted in numerous clones, some of which displayed heterogeneity in terms of growth, antigen expression, and the ability to release cytokines. The successes and failures associated with generating TC lines are discussed in this article. Both parental cultures and related clones serve as critical reagents for the continued study of the cellular immune response to NSCLC.

The influence of different culture microenvironments on the generation of dendritic cells from non-small-cell lung cancer patients

INTRODUCTION

Monocyte-derived dendritic cells (DCs) are currently under extensive evaluation as cell vaccines for cancer treatment. Many protocols regarding DCs generation in vitro with different protein components, especially autologous proteins, have been described. On the other hand, active tumor-derived factors in patients' serum could impair monocytes, which might result in their abrogated differentiation into DCs in vitro.

MATERIALS AND METHODS

Autologous DCs from non-small-cell lung cancer (NSCLC)-bearing patients were generated in different culture microenvironments. Peripheral blood mononuclear cells (PBMCs) were cultured in the presence of interleukin-4 and granulocyte-monocyte-stimulating factor with supplementation of 10% autologous serum, 10% allogenic serum, or 2% human albumin. The course of apoptosis, phagocytic ability, and the immunophenotype of the generated DCs were analyzed using flow cytometric methods.

RESULTS

After 48 h of culture, we found a lower percentage of CD1a+/CD14+ and a higher percentage of CD1a+/CD14(-) cells in the culture supplemented with human albumin than in the cultures supplemented with serums. The lowest CD14 antigen expression was found in the human albumin-supplemented 48-h cultures. After 48 h in the cultures carried out with human albumin we found significantly higher percentages of AV+/PI+ cells and AV(-)/PI+ cells than in cultures supplemented with autologous or allogenic serum. We also noted that the expression of FITC-dextran after 4 and 24 h of incubation was significantly higher in the cultures supplemented with both serums than in the HA-SC. The percentage of semi-mature DCs and of CD83 expression was lowest in the culture supplemented with 2% human albumin.

CONCLUSIONS

The kind of culture supplementation had a great impact on the apoptosis of cultured PBMCs. It could also influence the yield of monocyte-derived DCs. It was also confirmed that autologous and allogenic serums provide suitable microenvironments for the generation of autologous DCs from NSCLC patients. The choice of culture supplementation for DC generation is still unsolved and further studies should be undertaken.

Vaccine therapy in non-small-cell lung cancer

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

Current approaches in dendritic cell generation and future implications for cancer immunotherapy

The discovery of tumor-associated antigens, which are either selectively or preferentially expressed by tumors, together with an improved insight in dendritic cell biology illustrating their key function in the immune system, have provided a rationale to initiate dendritic cell-based cancer immunotherapy trials. Nevertheless, dendritic cell vaccination is in an early stage, as methods for preparing tumor antigen presenting dendritic cells and improving their immunostimulatory function are continuously being optimized. In addition, recent improvements in immunomonitoring have emphasized the need for careful design of this part of the trials. Still, valuable proofs-of-principle have been obtained, which favor the use of dendritic cells in subsequent, more standardized clinical trials. Here, we review the recent developments in clinical DC generation, antigen loading methods and immunomonitoring approaches for DC-based trials.

Issues concerning the large scale cryopreservation of peripheral blood mononuclear cells (PBMC) for immunotherapy trials

Immunotherapy of cancer is being developed as an alternative or adjuvant to conventional therapies such as: surgery, chemotherapy and/or radiation treatment. Immunotherapy laboratories routinely process and prepare for injection large numbers of anti-tumor effector cells. The process of cryopreservation is critical to the success of immunotherapy. Standardized safe procedures are required. In the current report, we show the ability to cryopreserve peripheral blood mononuclear cells (PBMC) in Plasmalyte-A, a fluid replacement medium approved by the FDA. These studies show that this medium can be used in place of human serum in terms of cell recovery, cell surface phenotype and response to PHA. However, T cell cytokine release stimulated through the CD3 receptor was altered following the cryopreservation process. These results are important toward the improvement of cryopreservation techniques for their use in immunotherapy.

Dendritic cell immunotherapy for the treatment of neoplastic disease

It has long been promised that dendritic cell immunotherapy would revolutionize the treatment of neoplastic disease. Now, more than 10 years since the publication of the first clinical data, a firmer understanding of immunology and dendritic cell biology is beginning to produce interesting clinical results. This article reviews the clinical trials that established many of the concepts with which today's investigators are achieving improved results, discusses issues in dendritic cell immunotherapy that are currently unresolved, and offers a perspective on the strategies that the authors believe will be important for the design of future vaccine trials, including the use of Toll-like receptor agonists as maturation agents, the accessory use of the plasmacytoid dendritic cell subset, and the maximization of T-cell help.

Production of myeloid dendritic cells (DC) pulsed with tumor-specific idiotype protein for vaccination of patients with multiple myeloma

BACKGROUND

Immunotherapy of cancer with DC vaccines has produced encouraging results in clinical trials. Antigen (Ag)-pulsed DC have elicited CD4+ and CD8+ T-cell immunity and tumor regression in humans. However, there is no standard method of DC production. The DC phenotype, number and Ag-loading process used in these studies have varied, making comparisons between trials difficult.

METHODS

In the present report a reproducible method was developed for the production of a DC-based vaccine. Monocytes were enriched by adhesion from healthy donor apheresis products and cultured with growth factors for maturation into DC. The cells were loaded with the tumor Ag idiotype proteins from patients with multiple myeloma. DC culture and Ag loading were performed in an automated and closed system. The DC product was characterized for phenotype by flow cytometry and for function in Ag uptake and Ag presentation.

RESULTS

These monocyte-derived DC expressed high levels of costimulatory molecules (CD80/86). Ag-pulsed DC functioned to induce allogeneic proliferative lymphocyte responses and Ag-specific cytotoxic T lymphocyte (CTL) responses. The DC viability, phenotype and function were well preserved following prolonged frozen storage. Aliquots from the product of a single DC preparation could be used for sequential vaccinations without batch to batch variability.

DISCUSSION

Ag-pulsed DC can be reproducibly generated for clinical use. These standardized methods are now being employed for a clinical trial to evaluate idiotype-pulsed DC vaccine therapy following non-myeloablative transplant for the treatment of multiple myeloma.

Present and future of lung cancer vaccines

New approaches are needed to improve the current treatment of lung cancer. Inducing an immune response against lung tumour cells with vaccines represents an attractive therapy. However, lung tumours had not been considered good targets for vaccine therapy and, therefore, immune approaches have not been studied extensively in this setting. Current experimental strategies for antitumour vaccines include the generation of active immune responses against specific tumour antigens. Understanding the mechanisms of antitumour immunity and identifying relevant tumour-specific antigens will probably improve therapeutic strategies and provide avenues for the future of lung cancer therapy. There have been a number of preclinical immunotherapy trials suggesting activity, and a smaller number of human clinical trials using various vaccines in lung cancer. Initial data from these trials have shown preliminary evidence of induction of immune responses and suggest clinical activity. This paper reviews some of the most important developments in vaccines for lung cancer.

Generation of DC-based vaccine for therapy of B-CLL patients. Comparison of two methods for enriching monocytic precursors

BACKGROUND

The generation of Ag-loaded DC under good manufacturing practice (GMP) conditions is logistically challenging and further compounded when the starting precursors need to be purified from B-CLL patients who have overwhelming numbers of circulating B-CLL cells and decreased numbers of monocytes.

METHODS

We have previously demonstrated that DC with endocytosed B-CLL apoptotic bodies are powerful stimulators of anti-leukemic T cells. In this study we compared counterflow elutriation and immunomagnetic separation for enriching monocyte precursors, and evaluated the feasibility of generating DC from B-CLL patients and the effects of cryopreservation.

RESULTS

Monocyte yield from a single leukapheresis product of a B-CLL patient varied from 1 x 108 to 10 x 108 total cells, from which 40-200 x 106 mature DC could be produced. Adequate numbers of monocytes could not be enriched from one patient with 0.2% monocytes in the leukapheresis product, and the target of 50 x 106 DC was barely achieved in another patient with 0.9% monocytes in the pheresed cells. These results suggested that successful production of DC is dependent on a minimum frequency of 1% CD14(+) monocytes in the leukapheresis product. Cryopreservation of tumor cell-loaded DC yielded a recovery rate of 86+/-4.4% upon thawing, with a total viability of 90+/-2.8%. Most importantly, cryopreserved Ag-loaded DC retained their morphology, phenotype and function.

DISCUSSION

The results demonstrate that adequate numbers of functional DC required for clinical therapy can be generated from patients who have >1% of CD14(+) monocytes in the leukapheresis product. Moreover, Ag-loaded DC can be cryopreserved and recovered without significant change in phenotype or function.