Lysis Of Autologous Tumor Cells Research Articles

CTIM-15. T CELL RESPONSE DYNAMICS IN PHASE 3 GLIOBLASTOMA PATIENTS IMMUNIZED WITH AUTOLOGOUS DENDRITIC CELLS PULSED WITH AUTOLOGOUS TUMOR CELL LYSATE

Abstract BACKGROUND 331 glioblastoma patients were immunized with autologous dendritic cells (DCs) pulsed with autologous tumor cell lysate or placebo in a Phase 3 clinical trial. Immunization with the pulsed DCs was associated with extended overall survival in both newly diagnosed and recurrent disease. Objective: To characterize T cell responses and T cell response dynamics in patients immunized with autologous dendritic cells pulsed with autologous tumor cell lysate. METHODS we performed T cell receptor sequencing on peripheral blood mononuclear cells from both newly diagnosed and recurrent glioblastoma patients that were treated with the pulsed DCs. Timepoints from both before and after immunization were compared to understand T cell response dynamics. RESULTS Expansion of several hundred new T cell clones as well as more than 700 previously detected T cell clones was detected over time in both newly diagnosed and recurrent GBM patients who were treated with the pulsed DCs. Investigation of the dynamics of the response demonstrated that further expansion was triggered by ongoing immunizations. Correlations between T cell response data and clinical outcomes are ongoing. CONCLUSION Immunization with autologous DCs pulsed with autologous tumor cell lysate induces broad spectrum immune responses in patients with glioblastoma.

Ferroptosis and Necroptosis Produced Autologous Tumor Cell Lysates Co-Delivering with Combined Immnoadjuvants as Personalized In Situ Nanovaccines for Antitumor Immunity.

Nanovaccine-based immunotherapy has been considered as a major pillar to stimulate the host immune system to recognize and eradicate tumor cells as well as establish a long-term immune memory to prevent tumor relapse and metastasis. However, the weak specificity and low cross-presentation of antigens, as well as the immunosuppressive microenvironments of tumor tissues, are still the major obstacles on exerting the therapeutic performance of tumor nanovaccines sufficiently. Herein, we design and construct cytosine guanine dinucleotide (CpG) oligodeoxynucleotide (ODN)-loaded aluminum hydroxyphosphate nanoparticles covered by Fe-Shikonin metal-phenolic networks (MPNs) (Alum-CpG@Fe-Shikonin NPs) as personalized in situ nanovaccines for antitumor immunity. Upon internalization by tumor cells, the shell of Fe-Shikonin MPNs will disassemble into Fe2+ and Shikonin to elicit the immunogenic cell death of tumor cells through ferroptosis and necroptosis. Then, dying tumor cell-released autologous tumor cell lysates will be absorbed by Alum NPs and codelivered with CpG ODN to professional antigen-presenting cells temporally and spatially to activate multistep cascade antitumor immune responses, including dendritic cell maturation, antigen cross-presentation, natural killer cell and cytotoxic T lymphocyte infiltrations, and tumor-associated macrophage repolarization. Benefiting from the synergistic effects of Alum NPs, CpG ODN, and Fe-Shikonin MPNs, our Alum-CpG@Fe-Shikonin NPs exhibit drastic cytotoxicity and accurate selectivity on eradicating primary tumor, strong abscopal effect on inhibiting distant tumor, and a long-term immune memory effect on preventing tumor metastasis and recurrence. Because our report provides a feasible strategy to in situ make full use of autologous tumor cell lysates, which present an entire spectrum of the patient's personal epitopes without complicated ex vivo processes, such as extraction, purification, and sequencing, it may promote the development of personalized nanovaccines for antitumor immunity.

Production of dendritic cell vaccines using different methods with equivalent results: Implications for emerging centers

Dendritic cell (DC) vaccines have demonstrated good efficacy in preventing relapse and in increasing survival of patients affected by a variety of both solid and hematological tumors. Most protocols used to generate these cells involve the automated separation of peripheral blood monocytes from patients. This approach requires specialized equipment, which elevates the cost of this type of therapy, potentially limiting the widespread access to patients. In this study, we compare the yield and quality of dendritic cells generated from monocytes and isolated by an automated method or by manual methods using gradient centrifugation. The results demonstrate the equivalence of the 3 methods in relation to the yield and final quality of the product, however with considerable differences between the costs of these procedures. In addition, this study also demonstrates the feasibility of the antigenic pulse with autologous tumor cell lysates, constituting a source of antigens, not only easily obtained and manipulated, but also specific to the patient's tumor. These findings may have important implications for emerging centers interested in using this medical approach and potentially increase the access of a greater number of patients to this therapeutic option.

Long-term Follow-up of CD20-directed Chimeric Antigen Receptor Adoptive T-cell Therapy

Chimeric antigen receptor (CAR) T cell therapy targeting B-cell antigens has led to unprecedented success in inducing complete response (CR) rates in refractory B-cell non-Hodgkin lymphomas (NHLs). We previously reported the results of a pilot trial testing a 3rd generation CAR with 4-1BB and CD28 costimulatory domains targeting CD20 in patients (pts) with relapsed B-cell lymphomas (NCT00621452). 3 pts received cyclophosphamide (CY) 1 g/m2 IV for lymphodepletion 2 days prior to a series of 3 CAR T cell infusions 2 to 5 days apart in escalating doses followed by 2 weeks of low-dose IL-2. Here, we report the long term follow up of 2 of these pts. The third pt, UPN-02, died of progressive mantle cell lymphoma (MCL) and myelodysplastic syndrome at ~26 months (mos) post-treatment. Pt UPN-03, with relapsed MCL, had no evaluable disease after an excisional biopsy following protocol therapy. He relapsed after 2 years with a left flank mass, which was then radiated. He was re-treated with CY lymphodepletion, a dose of 1.8 x 109 CAR T cells/m2, and low-dose IL-2. At 6 weeks post infusion, he developed a small mass at the margin of his previous radiation field suspected to be recurrent MCL. This mass spontaneously regressed 1 mo later. Subsequent CT scans showed a residual soft tissue mass that gradually decreased over time and met criteria for CR by CT criteria. He remained in remission, albeit with detectable minimal residual disease (MRD) by ClonoSEQ assay, for the next 8.4 years until developing a subcutaneous chest mass and axillary adenopathy with biopsy showing recurrent MCL. Pt UPN-04, with relapsed follicular lymphoma (FL), had stable disease by CT at 1 mo but went on to have a partial response at ~3 mos. By 12 mos post-CAR T treatment there was evidence of progressive disease. However, between 2.5 and 3 years post-treatment he experienced resolution of all palpable nodes, and a near-CR was confirmed by CT at 35 mos after treatment. He remained without any clinical signs of progression with low level MRD by ClonoSEQ for the next 4 years. At 7.2 years post-CAR T cell treatment, he was found to have recurrent FL. CAR T cells were detectable for up to 12 mos in UPN-03 and 9 mos in UPN-04 by qPCR assay. B-cell recovery over time in both pts confirmed a lack of functional CAR T cell persistence. Given these findings, along with the durable responses observed in both pts, we hypothesized that these late remissions were caused by endogenous immune responses triggered by CAR T cell therapy. To evaluate this, we performed western blot assays incubating post-infusion serum with autologous tumor cell lysates followed by incubation with an anti-human IgG antibody, which showed new bands at post clinical response timepoints in both pts. ELISPOT assays with PBMCs co-incubated with autologous tumor cells exhibited spikes in IFN-γ secreting cells compared with control cells at timepoints proximal to their clinical responses. These findings suggested the occurrence of both humoral and cellular anti-tumor responses. To better characterize the T-cell response, we performed high-throughput TCR-β sequencing (Adaptive ImmunoSEQ) for UPN-04. We conducted a differential abundance analysis to identify possible tumor-reactive T cells, with the hypothesis that tumor-reactive T cell clones would be increased near the timepoints with clinical responses at ~3 and 35 mos. We identified 12 and 7 sequences, respectively, at these timepoints that were significantly increased compared to baseline (FDR < 0.05) and not present in the CAR-T product; 3 sequences were present at both 3 and 35 mos, and 1 of these was also significantly enriched in a post-infusion tumor biopsy, suggesting possible tumor-specificity. These results support the hypothesis that the late responses were mediated by endogenous T cells rather than CAR T cells. In summary, we report long-term remissions in 2 of 3 pts treated with CD20-targeted CAR T cell therapy, with evidence of endogenous anti-tumor immune responses. Together with previously published reports of epitope spreading after CAR-T for solid tumors, and in mouse models of lymphoma, these results suggest that CAR T cells have the capacity to elicit endogenous anti-tumor immune responses in lymphoma. Our use of CY without fludarabine as lymphodepletion may have facilitated such responses. Future research is warranted to enhance epitope spreading after CAR-T therapy as a bulwark against escape by antigen loss or loss of CAR-T persistence.

A Hybrid Glioma Tumor Cell Lysate Immunotherapy Vaccine Demonstrates Good Clinical Efficacy in the Rat Model.

BackgroundConventional immunotherapy for glioma is not only expensive but also demonstrates less-than-desired clinical efficacy. In this study, we evaluated the immunotherapeutic efficacy of a tumor cell lysate-based hybrid glioma vaccine developed using a molecular-based approach.MethodsFirst, the ability of the autologous (9L-cell lysate) and allogeneic (C6-cell lysate) vaccines against glioma, individually and in combination, to activate Fischer344 rat dendritic cells (DCs) was determined. Next, the activated DCs were co-cultured with T lymphocytes and screened for the optimal DC-to-T-cell ratio. The in vitro efficacy of the DC/T-cell vaccine formulations subjected to different immunogen treatments and co-cultured with glioma cells was evaluated based on glioma cell viability and monocyte chemoattractant protein (MCP)-2 and interferon (IFN)-γ secretion. Subsequently, the efficacy of the 9L + C6 hybrid vaccine was evaluated in 32 glioma rat models, randomly allocated to the following five treatment groups: blank control, tumor, vaccine treatment, thymosin treatment, and vaccine + thymosin treatment (combined treatment). Changes in survival duration, intracranial tumor volume, peripheral blood immune-cell (CD4+ T, CD8+ T, and natural killer [NK] cell) count, and serum cytokine (interleukin [IL]-2, IL-10) levels were assessed in these groups.ResultsThe hybrid vaccine demonstrated the highest glioma cell apoptosis and the lowest cell viability and promoted MCP-2 and IFN-γ secretion in vitro. The vaccine treatment and combined treatment groups demonstrated longer survival duration, lower intracranial tumor volume, and higher immune cell glioma tissue infiltration and IL-2 secretion than the untreated tumor group, indicating the vaccine’s good in vivo efficacy. Thymosin treatment had minimal effect in enhancing anti-glioma immunity.ConclusionWe demonstrated the feasibility of combining autologous and allogeneic tumor cell lysates to stimulate specific host cell immune response against glioma cells. The good clinical efficacy of our developed glioma hybrid vaccine in rat models suggests its potential clinical application.

Bispecific T-Cell Engager (BiTE) Antibody Based Immunotherapy for Treatment of Relapsed Refractory Multiple Myeloma (RRMM): A Systematic Review of Preclinical and Clinical Trials

Introduction Bispecific T-cell engager (BiTE) antibodies represent a novel therapeutic option for patients with multiple myeloma (MM). BiTE antibodies lack Fc region, and have variable domain only, they can simultaneously bind to two different epitopes i.e. cluster of differentiation 3 (CD3) molecules on tumor-specific T cells, and a specific antigen on myeloma cells, which leads to T-cell dependent destruction of myeloma cells. Currently, blinatumomab, specific for CD3 and CD19 is the only Food and Drug Administration FDA approved BiTE antibody for clinical use in patients with relapsed/refractory (RR) B-cell acute lymphoblastic leukemia, several similar BiTE antibodies are under development. Methods Following PRISMA guidelines, we performed comprehensive literature on 4/15/19 cross-referencing the terms "bispecific antibodies" and "multiple myeloma" using PubMed, Embase, Web of Science, Cochrane Library, Clinicaltrials.gov and review of international medical meeting abstracts. Initially, 256 articles were identified and after detailed scrutiny, one phase 1 clinical trial with prelim results, 4 preclinical and 4 ongoing clinical trials were included. Results Preclinical trials: Anti-BCMA x Anti-CD3 Bispecific Antibody: BiTE antibodies are still in early development in MM, and most of the published data is about the pre-clinical phase. In preclinical trials, Hipp et al. 2017 and Cho et al. 2018 reported that AMG 420 (BI 836909) and AMG 701, which are anti CD3 and B-cell maturation antigen (BCMA), are highly efficacious in vitro in the killing of myeloma cells and potently induces autologous tumor cell lysis in patients with both newly diagnosed and RRMM regardless of their disease status. In mouse xenograft models reconstituted with human T cells, in vivo efficacy of AMG 420 was reported with an overall response in 6 of 10 animals, with all 6 responders became tumor-free at the end of the study. In an orthotopic L-363 xenograft model, treatment with AMG 420 resulted in prolonged median survival of 43-43.5 days. Dilillo et al. 2018 and Ji Li et al. 2017 reported similar in vivo results for REGN5458 and BFCR4350A respectively. Clinical trials: Currently, there are 5 phase 1 ongoing clinical trials (Table 1). Updated results of only first in human phase I AMG 420 are available. Forty-two MM patients with a high tumor burden and four prior lines of therapy were given 2.5 treatment cycles with AMG 420. Overall thirteen (31%) patients responded to AMG 420 therapy, with complete response (CR) in 6 (14.2%) patients, very good partial response (VGPR) in 2 (5%) patients and partial response (PR) in 2(5%) patients. Eleven of these patients responded in the first treatment cycle, with a median response time of 1 month. Twenty-five (57.1%) patients discontinued treatment due to progressive disease. Four deaths were reported; 2 from disease progression and 2 due to adverse events; neither of them was treatment-related. Serious adverse events were reported in twenty-one (50%) patients, the infection was reported in twelve (29%) and polyneuropathy in three (7%), eighteen (43%) required hospitalization. Treatment-related serious adverse events included three (7%) patients with grade 2-3 cytokine release syndrome, three (7%) with polyneuropathy and one (2.3%) with edema. Conclusion After the success of naked antibodies like daratumumab and elotuzumab for MM, there is a need to develop immunotherapy using conjugated antibodies and BiTE antibodies to overcome the challenge of MM resistance and relapse to prior therapies. Preclinical data with BiTE antibodies are promising; AMG 420 anti-CD3/BCMA BiTE has already been granted fast track status by the FDA. We anticipate that drug will enter phase 2 clinical trials for drug development against RRMM Other BiTE antibodies with strong preclinical efficacy are under development and data from larger prospective clinical trials is needed to explore their efficacy in the treatment of multiple myeloma. Table 1 Disclosures Anwer: In-Cyte: Speakers Bureau; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees.

PEGylated tumor cell membrane vesicles as a new vaccine platform for cancer immunotherapy

Despite the promise and advantages of autologous cancer cell vaccination, it remains challenging to induce potent anti-tumor immune responses with traditional immunization strategies with whole tumor cell lysate. In this study, we sought to develop a simple and effective approach for therapeutic vaccination with autologous whole tumor cell lysate. Endogenous cell membranes harvested from cancer cells were formed into PEGylated nano-vesicles (PEG-NPs). PEG-NPs exhibited good serum stability in vitro and draining efficiency to local lymph nodes upon subcutaneous administration in vivo. Vaccination with PEG-NPs synthesized from murine melanoma cells elicited 3.7-fold greater antigen-specific cytotoxic CD8+ T lymphocyte responses, compared with standard vaccination with freeze-thawed lysate in tumor-bearing mice. Importantly, in combination with anti-programmed death-1 (αPD-1) IgG immunotherapy, PEG-NP vaccination induced 4.2-fold higher frequency of antigen-specific T cell responses (P < 0.0001) and mediated complete tumor regression in 63% of tumor-bearing animals (P < 0.01), compared with FT lysate + αPD-1 treatment that exhibited only 13% response rate. In addition, PEG-NPs + αPD-1 IgG combination immunotherapy protected all survivors against a subsequent tumor cell re-challenge. These results demonstrate a general strategy for eliciting anti-tumor immunity using endogenous cancer cell membranes formulated into stable vaccine nanoparticles.

CXCR5+CD8+ T cells infiltrate the colorectal tumors and nearby lymph nodes, and are associated with enhanced IgG response in B cells

Colorectal cancer is the third most prevalent cancer type worldwide and contributes to a significant percentage of cancer-related mortality. Recent studies have shown that the CXCR5+CD8+ T cells present more potent proinflammatory function than CXCR5−CD8+ T cells in chronic virus infections and in follicular lymphoma, but the role of CXCR5+CD8+ T cells in colorectal cancer is yet unclear. In this study, we demonstrated that CXCR5+CD8+ T cells were very rare in peripheral blood mononuclear cells from healthy and colorectal cancer individuals, but were significantly enriched in resected tumors and tumor-associated lymph nodes. Compared to CXCR5−CD8+ T cells, the CXCR5+CD8+ T cells demonstrated significantly higher Bcl-6 expression and lower Blimp1 expression, suggesting that CXCR5+CD8+ T cells might represent a memory CD8+ T cell subset. CXCR5+CD8+ T cells also enhanced the IgG expression by autologous B cells. Under ex vivo condition, the CXCR5+CD8+ T cells demonstrated lower degranulation, TNFα expression and IFNγ expression than CXCR5−CD8+ T cells. However, after PMA + ionomycin stimulation, the degranulation and TNFα expression by CXCR5+CD8+ T cells were significantly elevated to a level comparable with CXCR5−CD8+ T cells, whereas the IFNγ expression by PMA + ionomycin-stimulated CXCR5+CD8+ T cells were significantly higher than that by CXCR5−CD8+ T cells. Following long-term TCR-stimulation, CXCR5+CD8+ T cells demonstrated significantly more potent proliferation capacity and higher IFNγ expression than CXCR5−CD8+ T cells. TCR-stimulated CXCR5+CD8+ T cells also showed a gradual downregulation in CXCR5 expression. We further found that TCR-stimulated CXCR5+CD8+ T cells demonstrated higher granzyme B production and induced more specific lysis of autologous tumor cells than CXCR5−CD8+ T cells. Together, these data demonstrate that CXCR5+CD8+ T cells represent a significant CD8+ T cell subset in colorectal tumors and have the potential to contribute to antitumor immunity, but their specific roles require further studies in vivo.

OA13.06 Autologous Dendritic Cells Loaded with Allogeneic Tumor Cell Lysate (Pheralys®) in Patients with Mesothelioma: Final Results of a Phase I Study

Mesothelioma is an aggressive malignancy without curative treatment options. We have previously shown promising activity of dendritic cell (DC) immunotherapy loaded with autologous tumor cell lysate (Hegmans 2013, Cornelissen 2016). Because of quality and quantity issues (availability, standardization etc) with the autologous lysate, we have developed an off-the-shelf allogenic tumor cell lysate from human mesothelioma cell lines (Pheralys®). Patients (pts) with advanced mesothelioma, either treatment naive, or non-progressing after chemotherapy, were included. Leucapheresis was performed to obtain an enriched monocyte fraction from which immature DC were generated which were loaded with the allogenic lysate. The DC were matured, frozen and stored. In subsequent cohorts of 3 pts 10, 25, or 50 × 106 DC were administered IV and intradermally, 3 times at a bi-weekly interval and after 3 and 6 months. Primary endpoint was toxicity occurring within 8 weeks after the first vaccination. Secondary endpoints were response rate (RR), progression free survival (PFS) and overall survival (OS). PFS and OS were determined from time of registration in the trial. Immunological read-outs were performed (DTH skin testing, peripheral blood testing). Nine pts (median age 69yrs, 8 male, 1 female) were included. All patients developed transient grade 1-fever and a grade 1-2 injection site reaction. No dose limiting toxicities or autoimmunity signs were observed. In 2 pts (22%), both treated with 25 ×106 cells, a partial response (PR) was observed, the other 7 pts had stable disease as best overall response. All patients are alive with a median follow up of 11.9 months after trial inclusion(range 7.6-16.5 months). Median PFS was 8.3 months (95% confidence interval (CI) 3.7-not yet reached), PFS at 12 months was 33% (95% CI 8%-62%). Data on immunological read outs are pending. DC immunotherapy with allogenic tumor cell lysate is safe and clinically active. Data on PFS and OS are promising and still maturing. The recommended dose for future studies will be 25 * 106 cells based on the responses and logistic reasons (the number of monocytes obtained during leucapheresis to generate 5 vaccinations). A randomized trial comparing DC therapy with Pheralys versus best supportive care as maintenance treatment after chemotherapy is planned to start in Q1 2017.

Autologous Tumor Cell Lysate-Loaded Dendritic Cell Vaccine Inhibited Tumor Progression in an Orthotopic Murine Model for Hepatocellular Carcinoma.

The immune status of the tumor microenvironment influences tumor progression, and hepatocellular carcinoma (HCC) with an immunosuppressive signature often is associated with a poor prognosis. This study examined the impact of a bone marrow-derived dendritic cell (DC) vaccine loaded with autologous tumor cell lysate on tumor progression and the tumor microenvironment using an orthotopic murine HCC model. An orthotopic murine HCC was established by implantation of Hepa1-6 cells in the liver. The impact of DC vaccine loaded with Hepa1-6 cell lysate on tumor progression, survival, and tumor-infiltrating lymphocytes and cytokines was examined. Treating mice with DC vaccine loaded with Hepa1-6 cell lysate inhibited the progression of murine HCC generated through orthotopic implantation of Hepa1-6 cells and resulted in a 90% survival rate by day 60 compared with a survival rate lower than 5% for untreated mice. This anti-tumor response was associated with inhibition of STAT3 phosphorylation within the tumor. The DC vaccine reduced accumulation of Foxp3+CD4+ regulatory T cells within the tumor microenvironment and prevented TGF-β production from the tumor tissue. Tumor cell lysate-loaded DC vaccine prevented HCC progression in a clinically relevant orthotopic murine HCC model. The effect of DC vaccine on the accumulation of Foxp3+CD4+ regulatory T cells within the tumor microenvironment and on the production of TGF-β suggests that tumor regression by DC vaccination may be associated with an altered immunosuppressive tumor microenvironment.

Induction of an antitumor response using dendritic cells transfected with DNA constructs encoding the HLA-A*02:01-restricted epitopes of tumor-associated antigens in culture of mononuclear cells of breast cancer patients.

Advances in oncoimmunology related to the definition of the basic mechanisms of the formation of antitumor immune response, as well as the opening of tumor-associated antigens recognized by immune cells, allowed to start developing ways to influence the effector cells of the immune system to generate effective antitumor cytotoxic response. We investigated the possibility to stimulate an antitumor response in a culture of mononuclear cells of breast cancer patients by dendritic cells transfected with HLA-A*02:01-restricted DNA constructs. We isolated dendritic cells from peripheral blood monocytes and delivered our constructs to these cells by magnetic transfection. Additionally, a series of experiments with loading of dendritic cells with autologous tumor cell lysate antigens was conducted. We have shown that dendritic cells transfected with the HLA-A*02:01-restricted DNA constructs are effective in inducing an antitumor response in a culture of mononuclear cells of breast cancer patients. Dendritic cells transfected with DNA constructor dendritic cells loaded with lysate antigens revealed a comparable stimulated cytotoxic response of mononuclear cells to these two ways of antigen delivery. We conclude that using DNA constructs in conjunction with patient stratification by HLA type allows the application of transfected DCs as an effective method to stimulate antitumor immunity in vitro.

Abstract CT229: Autologous dendritic cells loaded with allogeneic tumor cell lysate in patients with mesothelioma: A phase I study

Abstract Malignant Mesothelioma (MM) is an aggressive disease without curative treatment options. Treatment with chemotherapy and surgery is accompanied with high incidences of local recurrences. Novel therapeutic treatment options are urgently needed and immunotherapy may be a new player in the field of MM. We have previously shown the feasibility of dendritic cell (DC) immunotherapy in MM (Hegmans, et al. Am J Respir Crit Care Med 2010). In these studies DC were loaded with autologous tumor cell lysate. Apart from safety also radiographical responses were found and survival was promising. However autologous tumor cell lysate has major drawbacks both in availability, quality and logistics. Therefore a new concept was developed, based on DC loading with a tumor cell lysate derived from human MM cell lines. In a murine MM model allogenic loading of DC's was equally safe, and effective as autologous (data submitted). We have developed a clinical grade allogenic batch of tumorcell lysate which is now used in a phase I study where patient diagnosed with MM are treated. This batch has been generated according to GMP and GLP regulations and a patent is pending. Orphan drug designation has been obtained from both FDA and EMA. For the trial, major inclusion criteria are chemonaïve patients or patients with a disease controle according to modified RECIST after standard chemotherapy. Patients with a need for high dosages of immunosuppressive therapy are excluded. In the study patients undergo a leukapheresis to collect monocytes. These monocytes are in vitro differentiated to DC's and pulsed with tumor lysate according to the previously described protocol. DCs are re-injected intravenous and intradermally every 2 weeks to determine toxicity. A 3*3 design study is initiated where chosen dosages are 10, 25 and 50* million cells. Primary endpoint is safety. Secondary endpoints are radiological responses according to modified RECIST for mesothelioma, progression free survival and overall survival. At present the study is open for inclusion. At the meeting results of the first dose cohorts will be presented. This will be the first in human study in MM with allogenic tumor cell loaded DC. In case no safety issues are encountered this may open the field of combination treatments (e.g. immunecheckpoint inhibition combined with DC treatment) to increase the population of patients who benefit from immunotherapeutic treatment options. Citation Format: Joachim G. Aerts, Robin Cornelissen, Cor van der Leest, Ferry Eskens, Koen bezemer, Margaretha Kaijen, Rudi Hendriks, Joost Hegmans, Henk C. Hoogsteden. Autologous dendritic cells loaded with allogeneic tumor cell lysate in patients with mesothelioma: A phase I study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT229. doi:10.1158/1538-7445.AM2015-CT229

Abstract 2491: Treatment with tumor lysate-pulsed autologous dendritic cells prolongs survival in patients with recurrent glioblastoma multiforme

Abstract Background The survival rate in recurrent Glioblastoma multiforme (rGBM) patients has not meaningfully changed in the past several decades. We have treated two cohorts of rGBM patients, one consisting of patients with early progression, and one of patients with progression following several cycles of adjuvant temozomolide chemotherapy, with autologous dendritic cells pulsed with autologous tumor cell lysate (DCVax®-L). Such treatment is intended to activate the immune system against the tumor cells, so that the ensuing immune attack may delay progression and time to death. Methods Disease progression in patients with GBM was determined through MRI. Progression needed to be determined by independent review on 2 consecutive scans for early progressor classification to avoid enrolling patients with pseudoprogression. Assessment of progression was done using modified RANO criteria. Results Nineteen (19) patients diagnosed with GBM were determined to have recurrence immediately following radiation therapy with concomitant temozolomide chemotherapy. Median overall survival in this cohort from initial GBM diagnosis is 15.1 months (95% CI: 10.5-17.2), and the range is 8.1-&amp;gt;31 months. A literature search revealed 6 publications with comparable populations of patients. The table below demonstrates that these patients typically have a life expectancy of 8-10 months. Reference (n)PopulationMedian Survival (95% CI)DCVax-L (19)PD post RT+chemo, confirmed 2 months later15.1 months (10.5 - 17.2)Brandes et al. 2008 (18)PD at 4 weeks pos RT+chemo, confirmed after two more tmz cycles10.2 months (n.a.)Roldan et al. 2009 (10)PD at 4-6 weeks post RT+chemo, confirmed after ≥1 more tmz cycle(s)9.1 months (4.9 - 19.1)Kang et al. 2010 (10)PD at 2 consecutive scans post RT+chemo10.8 (n.a.)Sanghera et al. 2010 (29)PD at 2 consecutive scans within 8 weeks post RT+chemo8.3 months (n.a.)Gunjur et al. 2011 (27)PD at 2 consecutive scans within 3 months post RT+chemo, or clinical deterioration10.4 months (n.a.)Linhares et al. 2013 (13)PD at 2 consecutive scans within 3 months post RT+chemo9.0 months (3.7 - 14.3) A second cohort of patients with rGBM consisted of 8 patients with recurrence following several adjuvant temozolomide treatment cycles. Median OS for these patients is 14.7 months from the time of surgery for first recurrence. The comparator for this cohort is derived from Friedman et al. (2009), who reported mOS of 8.7-9.3 months from the time of first recurrence for rGBM patients treated with Bevacizumab with or without Irinotecan. Results and Conclusion These results suggest that treatment with DCVax-L can extend survival by 5 months or more in patients with rGBM. Citation Format: Marnix Bosch, Robert Prins, Linda Liau. Treatment with tumor lysate-pulsed autologous dendritic cells prolongs survival in patients with recurrent glioblastoma multiforme. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2491. doi:10.1158/1538-7445.AM2015-2491

Cytotoxicity of human endogenous retrovirus K-specific T cells toward autologous ovarian cancer cells.

To determine whether HERV-K envelope (ENV) protein could function as a tumor-associated antigen and elicit specific T-cell responses against autologous ovarian cancer cells. The expression of HERV-K transcripts and ENV protein, the presence of serum antibodies against HERV-K, reverse transcriptase (RT) activities, and cellular immune responses in primary ovarian cancer tissues and patient blood samples were analyzed and compared with samples from patients with benign ovarian diseases and normal female donors. Ovarian cancer cells in primary tumors and ascites expressed markers of cancer stem cells and markers of both mesenchymal and epithelial cells. Expression of HERV transcripts and HERV-K ENV protein and reverse transcriptase activities were higher in ovarian cancer compared with adjacent normal and benign tissues. The ovarian cancer patient plasma also had high reverse transcriptase activities and the ovarian cancer patient sera contained HERV-K immunoreactive antibodies. HERV-K-specific T cells generated from autologous dendritic cells pulsed with HERV-K ENV antigens exhibited phenotypes and functions consistent with a cellular immune response including T-cell proliferation, IFNγ production, and HERV-K-specific cytotoxic T lymphocyte (CTL) activity. Significantly higher CTL lysis of autologous tumor cells than of uninvolved normal cells was demonstrated in patients with ovarian cancer than patients with benign diseases and further enhanced lysis was observed if T regulatory cells were depleted. Endogenous retroviral gene products in ovarian cancer may represent a potentially valuable new pool of tumor-associated antigens for targeting of therapeutic vaccines to ovarian cancer. Clin Cancer Res; 21(2); 471-83. ©2014 AACR.

Autologous Dendritic Cell Based Adoptive Immunotherapy of Patients with Colorectal Cancer—A Phase I-II Study

Dendritic cell-based active immunotherapies of cancer patients are aimed to provoke the proliferation and differentiation of tumor-specific CD4(+) and CD8(+) T-lymphocytes towards protective effector cells. Isolation and in vitro differentiation of circulating blood monocytes has been established a reasonable platform for adoptively transferred DC-based immunotherapies. In the present study the safety and tolerability of vaccination by autologous tumor cell lysates (oncolysate)- or carcinoembriogenic antigen (CEA)-loaded DCs in patients with colorectal cancer was investigated in a phase I-II trial. The study included 12 patients with histologically confirmed colorectal cancer (Dukes B2-C stages). Six of the patients received oncolysate-pulsed, whereas the other six received recombinant CEA-loaded autologous DCs. The potential of the tumor antigen-loaded DCs to provoke the patient's immune system was studied both in vivo and in vitro. The clinical outcome of the therapy evaluated after 7 years revealed that none of the six patients treated with oncolysate-loaded DCs showed relapse of colorectal cancer, whereas three out of the six patients treated with CEA-loaded DCs died because of tumor relapse. Immunization with both the oncolysate- and the CEA-loaded autologous DCs induced measurable immune responses, which could be detected in vivo by cutaneous reactions and in vitro by lymphocyte proliferation assay. Our results show that vaccination by autologous DCs loaded with autologous oncolysates containing various tumor antigens represents a well tolerated therapeutic modality in patients with colorectal cancer without any detectable adverse effects. Demonstration of the efficacy of such therapy needs further studies with increased number of patients.

Allogeneic partially HLA-matched dendritic cells pulsed with autologous tumor cell lysate as a vaccine in metastatic renal cell cancer

Multi-kinase inhibitors have been established for the treatment of advanced renal cell cancer, but long-term results are still disappointing and immunotherapeutic approaches remain an interesting experimental option particularly in patients with a low tumor burden. DC are crucial for antigen-specific MHC-restricted T cell immunity. Furthermore, allogeneic HLA-molecules pose a strong immunogenic signal and may help to induce tumor-specific T cell responses. In this phase I/II trial, 7 patients with histologically confirmed progressive metastatic RCC were immunized repetitively with 1 × 107 allogeneic partially HLA-matched DC pulsed with autologous tumor lysate following a schedule of 8 vaccinations over 20 weeks. Patients also received 3 Mio IE IL-2 s.c. once daily starting in week 4. Primary endpoints of the study were feasibility and safety. Secondary endpoints were immunological and clinical responses. Vaccination was feasible and safe with no severe toxicity being observed. No objective response could be documented. However, while all patients had documented progress at study entry, 29% of the patients showed SD throughout the study with a mean TTP of 24.6 weeks (range 5 to 96 weeks). In 3/7 patients, TH1-polarized immune responses against RCC-associated antigens were observed. In one patient showing a minimal clinical response and a TTP of 96 weeks, clonally proliferated T cells against yet undefined antigens were induced by the vaccine. Vaccination with tumor antigen loaded DC remains an interesting experimental approach, but should rather be applied in the situation of minimal residual disease after systemic therapy. Additional depletion of regulatory cells might be a promising strategy.

Vaccination for invasive canine meningioma induces in situ production of antibodies capable of antibody-dependent cell-mediated cytotoxicity.

Malignant and atypical meningiomas are resistant to standard therapies and associated with poor prognosis. Despite progress in the treatment of other tumors with therapeutic vaccines, this approach has not been tested preclinically or clinically in these tumors. Spontaneous canine meningioma is a clinically meaningful but underutilized model for preclinical testing of novel strategies for aggressive human meningioma. We treated 11 meningioma-bearing dogs with surgery and vaccine immunotherapy consisting of autologous tumor cell lysate combined with toll-like receptor ligands. Therapy was well tolerated, and only one dog had tumor growth that required intervention, with a mean follow up of 585 days. IFN-γ-elaborating T cells were detected in the peripheral blood of 2 cases, but vaccine-induced tumor-reactive antibody responses developed in all dogs. Antibody responses were polyclonal, recognizing both intracellular and cell surface antigens, and HSP60 was identified as one common antigen. Tumor-reactive antibodies bound allogeneic canine and human meningiomas, showing common antigens across breed and species. Histologic analysis revealed robust infiltration of antibody-secreting plasma cells into the brain around the tumor in posttreatment compared with pretreatment samples. Tumor-reactive antibodies were capable of inducing antibody-dependent cell-mediated cytotoxicity to autologous and allogeneic tumor cells. These data show the feasibility and immunologic efficacy of vaccine immunotherapy for a large animal model of human meningioma and warrant further development toward human trials.

Expression of selected regulatory molecules on the CD83+ monocyte-derived dendritic cells generated from patients with laryngeal cancer and their clinical significance

B7H1 and B7H4 overexpression is associated with inhibition of the immune system in many solid tumors, and altogether with CD200 molecule plays an important role in tumor invasion by promoting malignant transformation. However, there is no report about impact of these molecules on laryngeal squamous cell carcinoma. The objective of the present study was to assess by means of flow cytometry the expression of B7H1, B7H4, CD200, and CD200R on CD83+ monocyte-derived dendritic cells (Mo-DC), pulsed with autologous tumor cell lysates (aTCL) in patients who suffer from G1, G2, or G3 laryngeal carcinoma (LC, n = 60) in comparison to healthy donors (HD, n = 15). It has been demonstrated that median value of the percentages of CD83+ B7H1+, CD83+ B7H4+, and CD83+ CD200+ cells were higher in LC patients than HD (p = 0.041, p ≤ 0.0001, and p = 0.02, respectively). Mean fluorescence intensity (MFI) of CD200, CD200R, B7H1, and B7H4 on the Mo-DC pulsed with aTCL of the patients was also higher than on the Mo-DC of HD (p ≤ 0.0001, p ≤ 0.0001, p = 0.002, and p ≤ 0.0001, respectively). The highest MFI levels of all molecules were noted in grade 3 LC. The aforementioned results prove that there is a relation between the presence of laryngeal cancer and the expression of B7H1, B7H4, CD200, and CD200R regulatory molecules on the CD83+ Mo-DC pulsed with autologous cancer cell lysates. Strong association of LC grade and the tested antigens expression suggests a critical role for these proteins in LC biology.

Expression of CD200 and CD200R regulatory molecules on the CD83+ monocyte-derived dendritic cells generated from patients with laryngeal cancer

CD200 molecule may play a role in local tumor invasion and augmenting the metastatic capacity of squamous cell carcinoma. The objective of the study was to assess by means of flow cytometry the expression of CD200 and its receptor, CD200R, on CD83+ monocyte-derived dendritic cells (Mo-DCs), pulsed or not with autologous tumor cell lysates (aTCL) in patients who suffer from laryngeal carcinoma in comparison to healthy donors. The median value of CD200 mean fluorescence intensity (MFI) on the Mo-DCs pulsed with aTCL of the patients with laryngeal cancer was 61.94 and was statistically significantly higher than on the unpulsed Mo-DCs of these patients (24.81) and healthy donors (16.63), p = 0.0034 and p = 0.0004, respectively. Median MFI score of CD200R in specimen derived from patients with laryngeal cancer was 259.31 on Mo-DCs pulsed with aTCL, while in unpulsed Mo-DCs was 86.74 (p = 0.0035) and on the Mo-DCs from control group it was 67.51 (p = 0.0004). The obtained results showed a relation between the presence of laryngeal cancer and the expression of CD200 and CD200R molecules on the CD83+ Mo-DCs pulsed with autologous cancer cell lysates. This analysis may have implications for setting new therapeutic options for cancer immunotherapy in the future.

The natural killer cell response and tumor debulking are associated with prolonged survival in recurrent glioblastoma patients receiving dendritic cells loaded with autologous tumor lysates

Recurrent glioblastomas (GBs) are highly aggressive tumors associated with a 6–8 mo survival rate. In this study, we evaluated the possible benefits of an immunotherapeutic strategy based on mature dendritic cells (DCs) loaded with autologous tumor-cell lysates in 15 patients affected by recurrent GB. The median progression-free survival (PFS) of this patient cohort was 4.4 mo, and the median overall survival (OS) was 8.0 mo. Patients with small tumors at the time of the first vaccination (< 20 cm3; n = 8) had significantly longer PFS and OS than the other patients (6.0 vs. 3.0 mo, p = 0.01; and 16.5 vs. 7.0 mo, p = 0.003, respectively). CD8+ T cells, CD56+ natural killer (NK) cells and other immune parameters, such as the levels of transforming growth factor β, vascular endothelial growth factor, interleukin-12 and interferon γ (IFNγ), were measured in the peripheral blood and serum of patients before and after immunization, which enabled us to obtain a vaccination/baseline ratio (V/B ratio). An increased V/B ratio for NK cells, but not CD8+ T cells, was significantly associated with prolonged PFS and OS. Patients exhibiting NK-cell responses were characterized by high levels of circulating IFNγ and E4BP4, an NK-cell transcription factor. Furthermore, the NK cell V/B ratio was inversely correlated with the TGFβ2 and VEGF V/B ratios. These results suggest that tumor-loaded DCs may increase the survival rate of patients with recurrent GB after effective tumor debulking, and emphasize the role of the NK-cell response in this therapeutic setting.