Autologous Dendritic Cells Research Articles

A Phase I-II multicenter trial with Avelumab plus autologous dendritic cell vaccine in pre-treated mismatch repair-proficient (MSS) metastatic colorectal cancer patients; GEMCAD 1602 study

BackgroundImmune check-point blockade (ICB) has shown clinical benefit in mismatch repair-deficient/microsatellite instability high metastatic colorectal cancer (mCRC) but not in mismatch repair-proficient/microsatellite stable patients. Cancer vaccines with autologous dendritic cells (ADC) could be a complementary therapeutic approach to ICB as this combination has the potential to achieve synergistic effects.MethodsThis was a Phase I/II multicentric study with translational sub-studies, to evaluate the safety, pharmacodynamics and anti-tumor effects of Avelumab plus ADC vaccine in heavily pre-treated MSS mCRC patients. Primary objective was to determine the maximum tolerated dose and the efficacy of the combination. The primary end-point was 40% progression-free survival at 6 months with a 2 Simon Stage. ResultsA total of 28 patients were screened and 19 pts were included. Combined therapy was safe and well tolerated. An interim analysis (Simon design first-stage) recommended early termination because only 2/19 (11%) patients were disease free at 6 months. Median PFS was 3.1 months [2.1–5.3 months] and overall survival was 12.2 months [3.2–23.2 months]. Stimulation of immune system was observed in vitro but not clinically. The evaluation of basal RNA-seq noted significant changes between pre and post-therapy liver biopsies related to lipid metabolism and transport, inflammation and oxidative stress pathways.ConclusionsThe combination of Avelumab plus ADC vaccine is safe and well tolerated but exhibited modest clinical activity. Our study describes, for the first-time, a de novo post-therapy metabolic rewiring, that could represent novel immunotherapy-induced tumor vulnerabilities.

P06.06.B standardization of therapy and manufacturing using tumor-associated antigen-stimulated autologous dendritic cells co-cultured with cytokine-induced killer cells in cancer immunotherapy

Abstract Background The application of DC-CIK in the field of cancer immunotherapy has been shown to be an effective treatment. However, the cost of DC-CIK treatment is prohibitive for many patients, and the lack of standard manufacturing processes and treatment strategies are the main limitations. Material and Methods Our experiments used tumor lysate instead of tumor cell line as tumor-associated antigen source with DCs co-culture. We provide the most efficient method for obtaining autologous DC-CIK cells from peripheral blood. Flow cytometry was used to evaluate DCs activation, CBA assay was used to quantify cytokines secreted by CIK cells, and the antitumor activity of DC-CIK was evaluated in vitro by K562 cell line. Results We demonstrate that the manufacturing process of employing frozen Peripheral Blood Mononuclear Cells (PBMCs) can balance patient’s comfort and economic benefits. DC-CIK can effectively upgrade the immunological specificity of CIK cells to tumors in the presence of tumor-associated antigen. In vitro experiments showed that when the number of DC: CIK cells was co-cultured in 1:20 ratio on the 14th day, the amount of cytokine secreted by CIK cells was the largest, and the anti-tumor immune effect was the most potent. When the number of CIK: K562 cells was in 25:1 ratio, the cytotoxic activity of CIK on K562 cells was the highest. Conclusion We developed an efficient activated fashion of DC:CIK, established the optimal ratio of DC-CIK immunologic activity and the best cytotoxic model of CIK to K562 cells.

1199TiP Phase I trial of in situ vaccination with autologous CCL21-modified dendritic cells (CCL21-DC) combined with pembrolizumab for advanced NSCLC

Effective immunotherapy options are lacking for patients with advanced NSCLC who progress on a PD-(L)1 inhibitor and for those that EGFR or ALK positive after progression on TKI therapy. One potential approach to improve ICI efficacy is to promote cytolytic T cell infiltration into tumors. This can be accomplished via in situ vaccination with functional antigen presenting cells which can take advantage of the full repertoire of tumor antigens and convert the tumor into a lymph node-like environment promoting both local and systemic T cell activation. The chemokine CCL21 promotes co-localization of naive T cells and antigen-experienced dendritic cells (DCs) to facilitate T cell activation. Our preclinical studies and phase I trial of intratumoral (IT) administration of DC genetically modified to overexpress CCL21 (CCL21-DC) revealed augmentation of tumor antigen presentation in situ, resulting in systemic antitumor immunity. However, increased PD-L1 expression was observed following therapy in some patient tumors, suggesting that tumor-mediated impairment of T cell function may be forestalling a more robust CCL21-DC mediated antitumor response. Therefore, we are conducting a phase I trial, combining IT CCL21-DC with pembrolizumab in patients with advanced NSCLC. Phase I, dose-escalating, trial followed by dose expansion. Maximum of 24 patients (9-12 escalation + 12 expansion) with stage IV NSCLC will be evaluated who have tumors accessible for IT injection and are either (1) EGFR/ALK wild-type after progression on a PD-(L)1 inhibitor or (2) EGFR/ALK mutant after progression on TKI therapy. Three IT injections of autologous CCL21-DC (days 0, 21, 42) will be concurrently administered with pembrolizumab, followed by q3wk pembrolizumab. Primary objective of dose escalation is safety and determination of maximum tolerated dose (MTD) of IT CCL21-DC (5x106, 1x107, or 3x107) when combined with pembrolizumab. Primary objective of dose expansion is objective response rate at MTD. Secondary objectives include adverse event profiling and determination of drug target activity by immune monitoring studies. This trial, NCT03546361, is currently open for enrollment. NCT03546361. The authors.

A personal COVID-19 dendritic cell vaccine made at point-of-care: Feasibility, safety, and antigen-specific cellular immune responses

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a world-wide pandemic. Internationally, because of availability, accessibility, and distribution issues, there is a need for additional vaccines. This study aimed to: establish the feasibility of personal dendritic cell vaccines to the SARS-CoV-2 spike protein, establish the safety of a single subcutaneous vaccine injection, and determine the antigen-specific immune response following vaccination. In Phase 1, 31 subjects were assigned to one of nine formulations of autologous dendritic cells and lymphocytes (DCL) incubated with 0.10, 0.33, or 1.0 µg of recombinant SARS-CoV-2 spike protein, and admixed with saline or 250 or 500 µg of granulocyte-macrophage colony-stimulating factor (GM-CSF) prior to injection, then assessed for safety and humoral response. In Phase 2, 145 subjects were randomized to one of three formulations defined by incubation with the same three quantities of spike protein without GM-CSF, then assessed for safety and cellular response. Vaccines were successfully manufactured for every subject at point-of-care. Approximately 46.4% of subjects had a grade 1 adverse event (AE); 6.5% had a grade 2 AE. Among 169 evaluable subjects, there were no acute allergic, grade 3 or 4, or serious AE. In Phase 1, anti-receptor binding domain antibodies were increased in 70% of subjects on day-28. In Phase 2, in the 127 subjects who did not have high levels of gamma interferon-producing cells at baseline, 94.4% had increased by day 14 and 96.8% by day 28. Point-of-care personal vaccine manufacturing was feasible. Further development of such subject-specific vaccines is warranted.

Asymmetric T cell division of GAD65 specific naive T cells contribute to an early divergence in the differentiation fate into memory T cell subsets.

Autoreactive T cells with the phenotype and function of different memory subsets are present in patients who developed type 1 diabetes (TID). According to the progressive differentiation model, memory subsets generate from naïve precursors in a linear and unidirectional path depending on the strength and quality of stimulatory signals. By observing human naïve T cells in contact with GAD65 loaded autologous dendritic cells, we observed that approximately 10% of cells divided with the plane of cell division parallel to the one of the immune synapse, causing phenotypic asymmetries in the proximal and distal daughter T cells. After the first T cell division, proximal and distal daughter T cells showed different phenotype, metabolic signature and commitment to differentiate towards long-lived memory T cells or T cells with effector function. Subjects with or without T1D showed a similar frequency of asymmetric T cell division (ATCD) for autoantigens and recall antigens specific T cells, however the frequency of ATCD is significantly increased in autoreactive T cells in patients with T1D when IL-7 was added to the culture. An increased upregulation of GLUT1 in response to IL-7 in patients with T1D was related to the rate of ATCD. Our results showed that ATCD is associated with an early divergence in the differentiation fate of naïve T cells specific for GAD65 during first antigen encounter.

Personalized tumor vaccine for pancreatic cancer.

Pancreatic cancer is a highly lethal malignancy often presenting with advanced disease and characterized by resistance to standard chemotherapy. Immune-based therapies such checkpoint inhibition have been largely ineffective such that pancreatic cancer is categorized as an immunologically "cold tumor". In the present study, we examine the therapeutic efficacy of a personalized cancer vaccine in which tumor cells are fused with dendritic cells (DC) resulting in the broad induction of antitumor immunity. In the KPC spontaneous pancreatic cancer murine model, we demonstrated that vaccination with DC/KPC fusions led to expansion of pancreatic cancer specific lymphocytes with an activated phenotype. Remarkably, vaccination led to a reduction in tumor bulk and near doubling of median survival in this highly aggressive model. In a second murine pancreatic model (Panc02), vaccination with DC/tumor fusions similarly led to expansion of tumor antigen specific lymphocytes and their infiltration to the tumor site. Having shown efficacy in immunocompetent murine models, we subsequently demonstrated that DC/tumor fusions generated from primary human pancreatic cancer and autologous DCs potently stimulate tumor specific cytotoxic lymphocyte responses. DC/tumor fusions induce the activation and expansion of tumor reactive lymphocytes with the capacity to infiltrate into the pancreatic cancer tumor bed.

Trial watch: Dendritic cell (DC)-based immunotherapy for cancer

ABSTRACT Dendritic cell (DC)-based vaccination for cancer treatment has seen considerable development over recent decades. However, this field is currently in a state of flux toward niche-applications, owing to recent paradigm-shifts in immuno-oncology mobilized by T cell-targeting immunotherapies. DC vaccines are typically generated using autologous (patient-derived) DCs exposed to tumor-associated or -specific antigens (TAAs or TSAs), in the presence of immunostimulatory molecules to induce DC maturation, followed by reinfusion into patients. Accordingly, DC vaccines can induce TAA/TSA-specific CD8+/CD4+ T cell responses. Yet, DC vaccination still shows suboptimal anti-tumor efficacy in the clinic. Extensive efforts are ongoing to improve the immunogenicity and efficacy of DC vaccines, often by employing combinatorial chemo-immunotherapy regimens. In this Trial Watch, we summarize the recent preclinical and clinical developments in this field and discuss the ongoing trends and future perspectives of DC-based immunotherapy for oncological indications.

Роль факторов иммуносупрессии в прогнозе эффективности клеточной иммунотерапии у пациентов с солидными опухолями

Production of different factors with wide immunosuppressive properties by tumor cells is one of the mechanisms that support tumor growth. We think that immunosuppressive action of tumor cells should be taken into account for cellular antitumor therapy optimization. Aim of the study – to evaluate the effectiveness of cellular immunotherapy factors (ISF) for response prediction in patients receiving tag7/PGRP-S gene modified tumor cells (GMV) or autologous dendritic cells vaccine (DCV) for melanoma (Mel), kidney cancer (RCC) and soft tissue sarcoma (STS). Material and methods. We have treated 204 patients with cellular therapy since 2001 till 2016 (88 – GMV, 1 16 – DCV). ISF (MICA, TGF-β, IL-10 и VEGF) were measured in tumor tissue cultures of 88 patients (71 – Mel, 6 – RCC, 11 – STS). Median age of patients was 51 year. Patient were divided as having insufficient response (IR) or sufficient response (SR) for the analysis purpose. Results. ISF concentration in cultures of patients with IR was higher than in patients with SR (р < 0.05). SR could be predicted correctly in 74.4% using ISF. The most important factor was TGF-β1. In the Cox model TGF-β1 and MICA levels were significant predictors of overall survival for Mel patients (р < 0.05). VEGF was the most important factor for time to progression prognosis. Spirman correlations showed moderate significant correlation between ISF (р < 0.05). Conclusions. ISF concentration in cell cultures obtained from the patients with Mel, RCC or STS is important independent predictive factor for time to progression and overall survival. Our data supports rigid selection criteria based on biological properties of tumor cells for patients receiving cellular therapy for solid tumors

Abstract CT571: Plasma proteomic markers prognostic or predictive for survival of patients with newly diagnosed glioblastoma who were treated in a phase II trial with standard care and the addition of the novel patient-specific dendritic cell vaccine AV-GBM-1

Abstract Standard aggressive therapy for primary newly diagnosed glioblastoma (GBM), which includes surgical resection followed by concurrent radiation therapy and temozolomide chemotherapy (RT/TMZ) and then maintenance TMZ, is associated with poor survival rates. Adding treatment with AV-GBM-1, a personal vaccine consisting of autologous dendritic cells (DC) pulsed with autologous tumor antigens (ATA) may improve survival. AV-GBM-1 is produced by incubating ATA with autologous DC. ATA are from a lysate of irradiated autologous GBM cells that were self-renewing in serum-free medium with factors that favor survival and proliferation of tumor initiating cells, i.e., stem cells and early progenitor cells. After recovery from RT/TMZ, GBM patients were injected subcutaneously with AV-GBM-1 admixed in granulocyte-macrophage colony-stimulating factor (GM-CSF) at weeks 1, 2, 3, 8, 12, 16, 20, and 24. This study examined changes in plasma proteomics before and after injections of AV-GBM-1. 57 patients were treated during November 2018 to October 2020. Median progression-free and overall survival were 10.3 and 16.0 months respectively. Plasma samples obtained at baseline (week-0), and just prior to the third injection (week-2) were cryopreserved and subsequently analyzed for 448 proteomic markers using quantitative, multiplex enzyme-linked immunosorbent assays (Raybiotech, Inc., Norcross, GA.). 54 patients had a baseline week-0 sample prior to the 1st vaccination; 50 had a week-2 sample just prior to the 3rd dose; 49 had paired samples for both time-points. The averages of paired samples were measured for all patients and for cohorts defined by median survival that were compared by 2-tail T-Tests. After two weekly injections there were significant (p<0.01) increases in thymus and activation-regulated chemokine (TARC, CCL17), chemerin, lipocalin-2 and angiopoietin, and decreases in thrombospondin-5, angiotensinogen, and beta-fibroblast growth factor. The changes in TARC are due to GM-CSF. 25 patients survived more than 15 months and 24 less than 15 months. Prognostic baseline markers associated with longer survival were higher CD14 (p=0.009), higher tissue-inhibitor of metalloproteinases (TIMP-1), and higher insulin growth factor binding proteins (IGFBP) 1 and 2 (p<0.02). The only markers that appeared predictive for survival (p<0.05) based on changes from baseline to week-2 were increased lipocalin-2, associated with longer survival (p=0.0369), and decreased brain-derived neurotrophic factor (BDNF) associated with shorter survival (p=0.0186). Because of the large number of analyses, these results are considered hypothesis generating and not definitive. Citation Format: Daniela A. Bota, David E. Piccioni, Christopher M. Duma, Renato V. LaRoca, Santosh Kesari, Mehrdad Abedi, Robert D. Aiken, Aleksandra J. Poole, Gabriel I. Nistor, Robert O. Dillman. Plasma proteomic markers prognostic or predictive for survival of patients with newly diagnosed glioblastoma who were treated in a phase II trial with standard care and the addition of the novel patient-specific dendritic cell vaccine AV-GBM-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT571.

Abstract CT219: Phase I trial of in situ vaccination with autologous CCL21 gene-modified dendritic cells (CCL21-DC) combined with pembrolizumab for advanced non-small cell lung cancer (NSCLC)

Abstract Background: Although immune checkpoint blockade (ICB) targeting Programmed Death-1/Programmed Death-Ligand 1 (PD-1/PD-L1) alone or in combination with chemotherapy is now a first-line option for patients with advanced NSCLC, the majority of patients do not benefit from anti-PD-1/PD-L1 monotherapy, and the combination with chemotherapy is often associated with toxicity. For patients who initially respond to PD-1/PD-L1 inhibition, many relapse after an initial response and are in need for innovative strategies to overcome the resistance to ICB. One possible approach is to utilize in situ vaccination with functional chemokine gene-modified antigen presenting cells (APCs) that take advantage of the full repertoire of tumor antigens in the tumor microenvironment (TME) in order to restore tumor antigen presentation, promote tumor infiltration of immune cells driven by chemokine gradient, and facilitate tumor-specific T cell activation, both locally and systemically. The chemokine CCL21 is a therapeutic candidate due to its ability to promote infiltration and co-localization of naïve T cells and antigen-experienced dendritic cells (DCs) and facilitate T cell activation. In preclinical studies as well as a phase I clinical trial, we observed that intratumoral (IT) injection of CCL21-DC induces the infiltration of autologous DC and T cells into the TME, and generates systemic tumor-specific immune responses against multiple tumor antigens. We also observed tumoral PD-L1 upregulation following CCL21-DC injection, which may hinder T cell function. Similarly, the lack of efficacy of PD-1/PD-L1 inhibitors could potentially be combated by enhanced T cell infiltration and augmented APC function in the TME following in situ vaccination with CCL21-DC. Therefore, we are currently evaluating the safety and efficacy of combining IT CCL21-DC and intravenous (IV) pembrolizumab in advanced NSCLC patients following progression on ICB or tyrosine kinase inhibitor (TKI) therapy in a phase I trial (NCT03546361). Methods: Phase I, dose-escalating, multi-cohort trial followed by dose expansion. Maximum of 24 patients (9-12 escalation + 12 expansion) with stage IV NSCLC will be evaluated who have tumors accessible for IT injection and are either EGFR/ALK wild-type after progression on a PD-(L)1 inhibitor or EGFR/ALK mutant after progression on TKI. Three IT injections of autologous CCL21-DC (days 0, 21, 42) will be concurrently administered with pembrolizumab, followed by q3wk pembrolizumab up to 1 year. Primary objective of dose escalation is safety and determination of maximum tolerated dose (MTD) of IT CCL21-DC when combined with pembrolizumab. Primary objective of dose expansion is objective response rate at MTD. Secondary objectives include adverse event profiling and immune monitoring studies. [B.L. and A.L. contributed equally to this work as first authors.] Citation Format: Bin Liu, Aaron Lisberg, Ramin Salehi-Rad, Jay Lee, Linh M. Tran, Kostyantyn Krysan, Raymond Lim, Camelia Dumitras, Zhe Jing, Michael Oh, Fereidoun Abtin, Robert Suh, Scott Genshaft, Scott Oh, Gregory Fishbein, Ciara M. O'Higgins, Anita Kaul, Kanwarpal Kahlon, Shahryar Ashouri, Jonathan Goldman, David Elashoff, Edward Garon, Steven Dubinett. Phase I trial of in situ vaccination with autologous CCL21 gene-modified dendritic cells (CCL21-DC) combined with pembrolizumab for advanced non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT219.

IMG-07. Contralateral transient contrast enhancement in a patient with IDH1wt MGMT promoter-methylated GBM responding to TMZ and individualized multimodal immunotherapy

Abstract Immunotherapy-induced MRI changes remain challenging when treating GBM patients with immunotherapy as part of a combined treatment. The iRANO criteria provide a decision-tree in order to avoid over- and under-treatment reactions when contrast-enhancing lesions become visible and should be interpreted. We report a 34-year female, 34 weeks pregnant, who presented with epilepsy, and was diagnosed with IDH1wt MGMT promoter-methylated GBM after biopsy. On MRI, the left occipital lesion was mostly cystic-necrotic with peripheral contrast enhancement, and crossed over the corpus callosum to the right. The volume was calculated as 64 cm³ (abc/2 formula). She was treated with radiochemotherapy and 12 TMZm cycles. Within each TMZ cycle 5 days of immunogenic cell death (ICD) therapy (5 injections with Newcastle Disease Virus and 5 sessions of modulated electrohyperthermia (Oncotherm 50 min 40-60 Watt) was added at days 8 to 12. After all chemo-/ICD-therapy we continued with active specific immunotherapy: two autologous mature monocyte-derived dendritic cell vaccines loaded with ICD therapy-induced serum-derived antigenic extracellular microvesicles and apoptotic bodies (IO-Vac®). One month after the second IO-Vac®, 17 months after diagnosis, a temporal right FLAIR-visible region showed expansion, and three months later also diffuse contrast enhancement, which was confirmed in a control scan one month later. The original tumor was meanwhile reduced to 16 cm³. However, in the last available scan, two months after the former, the contrast enhancement was disappeared, and the pathologic area on FLAIR was diminished. The original tumor size was reduced to 2 cm³, two year after first diagnosis. She showed allergic skin reactions to TMZ, which was covered with systemic histamine intake. There were no side effects related to multimodal immunotherapy. Transient MRI changes can be observed even in distance from the original tumor and can be interpreted as immune-mediated effects when the original tumor is responding.

IMMU-07. Interim analysis of the HIT-HGG Rez Immunvac study - Dendritic cell vaccination with partial Treg depletion and double checkpoint blockade in children with relapsed high-grade gliomas.

Relapses of high-grade gliomas show an aggressive course and survival 6 months after (sub-)total re-resection was only 62% in former HIT-HGG trials. Immunotherapy by induction of tumor-specific T cells through active immunization might help to control glioma regrowth. In the HIT-HGG-Rez Immunovac trial (Eudra-CT 2013-000419-26) we investigate whether a therapeutic vaccine (autologous dendritic cells loaded with tumor lysate, DCV) combined with Treg-depletion and double checkpoint-inhibition (CI, anti-PD-1/anti-CTLA4) is able to increase the number of patients alive 6 months after relapse. Here, we report interim results after 50% of the intended patients (n=25) have been recruited. 13 children and adolescents (mean age 12.7±4.0 y) with relapsed glioblastomas were screened for the trial so far. Three patients were screening failures, 10 patients received study treatment. Of these, 2 patients are currently vaccinated, so that 8 patients were evaluable for this interim analysis. 5 SAEs have been reported so far, none of them was limiting. 4 patients with gross total or subtotal resection at time of relapse had an overall survival (OS) of 13.2±4.0 months and a 6-month survival rate of 100%, which compares favourably to historical controls. 4 partially resected patients survived only 5.1±1.3 months and 6-months OS was 25%. Treg-depletion lead to a reduction of CD4+CD127-CD25+ T-cells of 45%, the majority of patients exhibited a tumor-specific T-cell response. We conclude that DCV in combination with partial Treg-depletion and CI is feasible, safe, and related with immunological responses. Double CI was not associated with unexpected toxicities. In (sub-)totally resected patients, immunotherapy seems to confer a survival advantage. For the completion of the trial we aim to include more patients with (sub-)totally resectable tumors to gain more insight into the nature and duration of the induced immune response. This trial is supported by Bristol Myers-Squibb (CA209-7JA).

Reproducibility of outcomes in sequential trials using CMV-targeted dendritic cell vaccination for glioblastoma.

2005 Background: Vaccination with dendritic cells (DCs) fares poorly in primary and recurrent glioblastoma (GBM). Moreover, GBM vaccine trials are often underpowered due to limited sample size. Methods: To address these limitations, we conducted three sequential clinical trials utilizing Cytomegalovirus (CMV)-specific DC vaccines in patients with newly diagnosed GBM eligible to receive standard of care resection and adjuvant radiation therapy and temozolomide chemotherapy. Autologous DCs were generated and electroporated with mRNA encoding for the CMV protein pp65. Serial vaccination was given throughout adjuvant temozolomide cycles, and 111Indium radiolabeling was implemented to assess migration efficiency of DC vaccines. Patients were followed for median overall survival (mOS) and OS. Results: Our initial study was the phase II ATTAC study (NCT00639639; total n = 12) with 6 patients randomized to vaccine site preconditioning with tetanus-diphtheria (Td) toxoid. This led to an expanded cohort trial (ATTAC-GM; NCT00639639) of 11 patients receiving CMV DC vaccines containing granulocyte-macrophage colony-stimulating factor (GM-CSF). Follow-up data from ATTAC and ATTAC-GM revealed 5-year OS rates of 33.3% (mOS 38.3 months; CI95 17.5-undefined) and 36.4% (mOS 37.7 months; CI95 18.2-109.1), respectively. ATTAC additionally revealed a significant increase in DC migration to draining lymph nodes following Td preconditioning ( P = 0.049). Increased DC migration was associated with OS (Cox proportional hazards model, HR = 0.820, P = 0.023). Td-mediated increased migration has been recapitulated in our larger confirmatory trial ELEVATE (NCT02366728) of 43 patients randomized to preconditioning (Wilcoxon rank sum, Td n = 24, unpulsed DC n = 19; 24h, P = 0.031 and 48h, P = 0.0195). In ELEVATE, median follow-up of 42.2 months revealed significantly longer OS in patients randomized to Td ( P = 0.026). The 3-year OS for Td-treated patients in ELEVATE was 34% (CI95 19-63%) compared to 6% given unpulsed DCs (CI95 1-42%). Conclusions: We report reproducibility of our findings across three sequential clinical trials using CMV pp65 DCs. Despite their small numbers, these successive trials demonstrate consistent survival outcomes, thus supporting the efficacy of CMV DC vaccine therapy in GBM. Clinical trial information: NCT00639639, NCT02366728.

Phase I trial of in situ vaccination with autologous CCL21-modified dendritic cells (CCL21-DC) combined with pembrolizumab for advanced NSCLC.

TPS9154 Background: Effective immunotherapy options are lacking for patients with advanced non-small cell lung cancer (NSCLC) who progress on a programmed cell death-(ligand)1 [PD-(L)1] inhibitor and for those that are epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement positive after progression on tyrosine kinase inhibitor (TKI) therapy. One potential approach to improve immune checkpoint efficacy in these patient populations is to promote cytolytic T cell infiltration into tumors. This can be accomplished via in situ vaccination with functional antigen presenting cells (APCs) which can take advantage of the full repertoire of tumor antigens and convert the tumor into a lymph node-like environment promoting both local and systemic T cell activation. The chemokine CCL21 promotes co-localization of naive T cells and antigen-experienced dendritic cells (DCs) to facilitate T cell activation. Our preclinical studies and phase I trial of intratumoral (IT) administration of DC genetically modified to overexpress CCL21 (CCL21-DC) revealed augmentation of tumor antigen presentation in situ, resulting in systemic antitumor immunity. However, increased PD-L1 expression was observed in some patient tumors, suggesting that tumor-mediated impairment of T cell function may be forestalling a more robust CCL21-DC mediated antitumor response. Similarly, improved PD-(L)1 inhibitor efficacy may be possible with enhanced T cell infiltration and augmented APC function following IT CCL21-DC. Therefore, we are conducting a phase I trial, combining IT CCL21-DC with pembrolizumab in patients with advanced NSCLC that are either (1) EGFR/ALK wild-type after progression on a PD-(L)1 inhibitor or (2) EGFR/ALK mutant after progression on TKI therapy. Methods: Phase I, dose-escalating, multi-cohort trial followed by dose expansion. Maximum of 24 patients (9-12 escalation + 12 expansion) with stage IV NSCLC will be evaluated who have tumors accessible for IT injection and are either (1) EGFR/ALK wild-type after progression on a PD-(L)1 inhibitor or (2) EGFR/ALK mutant after progression on TKI therapy. Three IT injections of autologous CCL21-DC (days 0, 21, 42) will be concurrently administered with pembrolizumab, followed by q3wk pembrolizumab up to 1 year. Primary objective of dose escalation is safety and determination of maximum tolerated dose (MTD) of IT CCL21-DC (5x106, 1x107, or 3x107) when combined with pembrolizumab. Primary objective of dose expansion is objective response rate at MTD. Secondary objectives include adverse event profiling and determination of drug target activity by immune monitoring studies. This trial is currently open for enrollment. Clinical trial information: NCT03546361.

A phase I clinical trial on intracranial administration of autologous myeloid dendritic cells (myDC) in combination with ipilimumab and nivolumab in patients with recurrent glioblastoma (rGB).

2033 Background: Intracerebral administration of ipilimumab (IPI) and nivolumab (NIVO) following resection of rGB was demonstrated to be safe and resulted in encouraging survival (Duerinck, Schwarze et al. JITC 2021; Neyns et al. ESMO 2021). CD1c(BDCA-1)+ and CD141(BDCA-3)+ myDC play a pivotal role in initiating an adaptive anti-tumor immune response by re-licensing cytotoxic T lymphocytes within the tumor microenvironment. Methods: Eligible patients (pts)(diagnosed with rGB following radiation and temozolomide treatment; not in need of steroids) underwent a leukapheresis followed by immunomagnetic bead isolation and cryopreservation of CD1c (BDCA-1)+ / CD141(BDCA-3)+ myDC. At the time of surgery, an escalating number of myDC (1, 10, and 20x106 myDC) were injected into the brain tissue lining the resection cavity following maximal safe resection of the rGB (ICer) or injected intratumorally (ITum) following stereotactic biopsy (STx). IPI (5 mg) plus NIVO (10 mg) were co-injected with myDC. NIVO was administered intracavitary (ICav, 10mg) using an Ommaya port and intravenously (IV, 10mg) Q2w (max 12x). Results: Fourteen pts (9 male; median 48y [range 20-78]) were recruited (resection n = 11; STx n = 2) and underwent a successful leukapheresis and isolation of myDC; peroperative administration of myDC was preceded by resection in 10 pts (1 pt did not undergo surgery due to clinical deterioration/cerebral edema), and by STx in 2 pts. Respectively 6 (incl both pts who underwent a STx), 3, and 4 pts were treated at the 3 dose levels. All pts received ITum/ICer/IV-administrations of IPI and NIVO as planned. Median number of postoperative ICav/IV NIVO-administrations was 7 (range 2-11). Most frequent adverse events (AE) were headache (n = 11), fatigue (n = 9), transient dysphasia (n = 6), and nausea (n = 5). Bacterial colonization of the Ommaya occurred in 3 pts necessitating removal. Immune-related AE were infrequent and mild. No G5 AE occurred. No dose-limiting toxicities were seen with increasing numbers of myDC. After a median follow-up of 54w, 3 pts remain progression-free (after 42+, 51+, 54+ weeks of FU), 6 (46%) pts have died; median PFS is 13w (95% CI 0-26), median OS has not been reached; 6-months PFS- and OS-rate are respectively 30% and 84%, 12-months PFS- and OS-rate are respectively 23% and 51%. OS compares favorably to an historical cohort of Belgian rGB patients (n = 469; Log-Rank p = 0.018). Gene expression profiling of resected tissue, analysis of cellular counts, cytokines, NIVO/IPI-concentrations in on-treatment cerebrospinal fluid samples is ongoing. Conclusions: Intracranial administration of autologous myDC plus IPI and NIVO in combination with IV NIVO was found to be feasible, sufficiently safe and associated with encouraging survival justifying further investigation in pts with resectable rGB. Clinical trial information: NCT03233152.

A randomised phase II clinical trial of low-dose cyclophosphamide and transarterial chemoembolization (TACE) with or without vaccination with dendritic cells (DC) pulsed with HepG2 lysate ex vivo in patients with hepatocellular carcinoma (HCC): The ImmunoTACE trial.

4012 Background: A previous study by our group using autologous monocyte-derived DC pulsed ex vivo with HepG2 cell lysate showed some clinical benefit with evidence of antigen-specific T-cell responses in patients with advanced HCC. The current trial reports the activity of this vaccine in combination with TACE in patients with HCC. All patients also received low-dose cyclophosphamide to deplete regulatory T cells and thereby enhance vaccination. Methods: Patients with intermediate stage HCC (performance status 0-2, Child Pugh A/B7) were randomised 1:1 to TACE plus low-dose cyclophosphamide (Group 1) or TACE plus low-dose cyclophosphamide plus dendritic cell vaccination (Group 2). Cyclophosphamide was administered on Day 1 and 29 followed by TACE on Day 31 (+/- DC infusion), with further cyclophosphamide on Days 60, 90 and 120 (+/- additional DC infusions on Days 62, 92 and 122). The primary endpoint was progression free survival (PFS) by RECIST v1.1. Secondary endpoints included radiological response by RECIST v1.1, PFS and radiological response according to modified (m) RECIST, overall survival (OS), immune response and toxicity. Target recruitment was 48 evaluable patients (24 patients in each arm) to detect a 20% increase in PFS rate at 1 year (30% vs 50%) with a relaxed one-sided statistical significance level of 20% and 80% power using a logrank test. Results: Between March 2016 and October 2019, 55 patients from 3 UK centres were randomised of whom 48 were evaluable (24 each arm). Median PFS by RECIST criteria was significantly longer in Group 2 compared to Group 1 (18.6 vs 10.4 months: hazard ratio (HR) 0.43, 80% CI -∞-0.59; one-sided p = 0.02). Median PFS using mRECIST criteria showed a similar magnitude of benefit (18.6 vs 10.8 months: HR 0.48, 95% CI 0.22-1.02). Median OS was 25.7 months in Group 2 vs 21.5 months in Group 1 (HR 0.61, 95% CI 0.27-1.38). Group 2 showed a higher overall response rate (complete and partial response) by RECIST (54% vs 29%) and mRECIST (75% vs 54%) and a higher disease control rate (complete and partial response and stable disease) by RECIST (92% vs 67%) and mRECIST (88% vs 67%). Treatment with DC infusions was well tolerated; the most common adverse events were chills (30%), fatigue (22%) and nausea (22%), all of which were low grade. Immune response analyses are currently ongoing. Conclusions: The addition of tumour lysate pulsed DC infusions to treatment with TACE plus low-dose cyclophosphamide significantly increased PFS in patients with HCC. To the best of our knowledge, this is the first randomised study to demonstrate efficacy using DC in HCC. Further investigation of the role of DC infusions in the treatment of HCC are warranted but will need to take into account the current evolving immunotherapy landscape. Clinical trial information: 11889464.

Seizures as treatment-emergent adverse events during glioblastoma clinical trials.

e14018 Background: Seizures are not an uncommon presenting symptom of glioblastoma (GBM), and may occur following surgery for GBM. Such seizures typically can be controlled with anti-epileptics, and the risk of seizures seems to decrease after concurrent radiation therapy and temozolomide chemotherapy (RT/TMZ). However, the risk of seizures theoretically might be increased in association with a therapeutic intervention designed to enhance local inflammation at the GBM site. 33% of patients experienced one or more seizures as a treatment-emergent-adverse-event (TEAE) during a phase II clinical trial of AV-GBM-1, patient-specific dendritic cell vaccines that consist of autologous dendritic cells loaded with autologous tumor associated antigens derived from a short-term culture of self-renewing tumor cells, that were injected subcutaneously for up to six months after recovery following concurrent RT/TMZ (Bota DA et al. 2021 Society for Immunotherapy of Cancer (SITC) late-breaking abstract #952, 2021 Society of Neuro-Oncology abstract #CTIM-33). A literature search was conducted to determine reported rates of seizures as TEAE in primary GBM patients in clinical trials. Methods: Phase III trials of systemic treatment of primary GBM, and published during 2005 to 2021, were identified by searches of clinicaltrials.gov and PubMed. Published reports were reviewed for data describing the frequency of seizures reported as TEAE in text and/or summary tables. Only trials that had at least 50 patients in a standard treatment arm of surgical resection, RT/TMZ and maintenance TMZ were included. Chi square test was used to compare proportions of patients experiencing seizures in these trials. Results: Eight such randomized trials were identified. Five trials did not mention seizures as TEAE. One trial provided data only for grade 3 and 4 events: 13/229 (5.7%). The other two trials reported all seizures regardless of grade, but were limited to patient populations with O6-methylguanine-DNA-methyltransferase promoter methylation in one, and epidermal growth factor receptor amplification in the other. The rates of seizures in those two trials were much lower than the 19/57 (33.0%) reported with AV-GBM-1: 28/258 (10.9%, p < 0.0001), and 69/372 (15.4%, p = 0.0136). Conclusions: The frequency of seizures that occur in GBM patients receiving standard RT/TMZ is not well-documented in publications of large, randomized trials. AV-GBM-1 may be associated with a higher rate of seizures because of treatment-induced inflammation at the tumor site, but a randomized trial would be needed to determine this.

In vitro preliminary study on different anti-PD-1 antibody concentrations on T cells activation

Lung adenocarcinoma predominates among diagnosed nonsmall cell lung cancer subtypes in nonsmokers. The introduction of immune checkpoint inhibitors into clinical practice offered patients prolonged progression-free survival and overall survival times. However, the results demonstrate that the benefits do not apply to all patients. Nivolumab is a monoclonal antibody against the PD-1 protein expressed mainly on T lymphocytes and is widely used in cancer therapy in different settings. Tumor cells often express the PD-L1 molecule and can effectively block the action of PD-1-positive lymphocytes. A body of knowledge regarding the high expression of PD-L1 on tumor cells highlights that it does not always correlate with the effectiveness of anti-PD-1 therapy. The side effects of the therapy also constitute a significant issue. These side effects can occur at any time during anti-PD-1 treatment and lead to discontinuation and even the death of the patient. In these situations, it is possible to delay the dosage. Nevertheless, unfortunately, it is not possible to reduce the dose of anti-PD-1 antibody, which would undoubtedly minimize side effects, leaving the patient's immune system active. In our preliminary study, we analyzed the effect of different concentrations of nivolumab on the functioning of T lymphocytes. Activation and proliferation markers were investigated on T cells after being cultured with antigen-stimulated autologous dendritic cells. This process may indicate an appropriate concentration of nivolumab, which shows clinical activity with minimal side effects.

CD8 T cell activation in cancer is comprised of two distinct phases

Abstract The CD8 T cell response to tumors is extremely variable with heterogenous T cell subsets, a stem-like CD8 T cell (PD1+TCF1+) that sustains the CD8 response and gives rise to a terminally differentiated (TD) cytotoxic cell (TCF1-Tim3+). Although these subsets have been described, how tumor-specific CD8 T cells are activated and differentiate in tumors are not well defined. Using a prostate cancer model that expresses the LCMV-GP (TRAMPC1-GP), we studied tumor-specific CD8 T cell activation by transferring LCMV-GP specific P14 CD8 T cells into tumor-bearing mice. We found that P14s are activated in the tumor-draining LNs (TDLNs) and acquire a stem-like phenotype. These cells migrate into the tumor as stem-like CD8 T cells and only differentiate into a TD CD8 T cell in the tumor. We found that stem-like CD8 T cells need additional co-stimulation from antigen presenting cells within the tumor to fully differentiate, even though they have been previously activated in TLDNs. Similarly, stem-like CD8s from human kidney cancer require both TCR and co-stimulatory signals to divide and differentiation ex-vivo and can differentiate when co-cultured with autologous dendritic cells. The addition of IL12 with TCR alone was not sufficient to induce differentiation, but improved differentiation when co-stimulation was present. This demonstrates the necessity of additional TCR and co-stimulation once activated stem-like CD8 T cells migrate into the tumor. Overall, these data suggest two distinct phases of CD8 T cell differentiation, the first occurs in the TDLN where they are initially activated. The second occurs in the tumor, where they require additional co-stimulation to differentiate and acquire an effector phenotype.

Αn optimized, simplified and clinically approved culture system to produce, in large scale, dendritic cells capable of priming specific T cells

Cancer immunotherapy using dendritic cells (DCs) able to induce specific immune responses to naïve T lymphocytes raises great research interest. However, the extremely complex and expensive methods used to produce DCs, combined with the limited number of autologous DCs in the circulation make any application almost impossible. Aim of the study is the development of an optimized and simplified system to easily produce in large scale cord blood-derived DCs, loaded with common tumor antigens, capable of promoting controlled Th1 immunoresponses following clinically approved maturation with vaccines. CD34+cells cultured in the presence of a cytokine cocktail in miniPERM® bioreactors and the generated DCs were matured using anti-flu vaccines. Autologous T cells plated with DCs pulsed with overlapping peptides CEA and WT1 for multiple stimulations. 200 billion of myeloid DCs were produced and matured in just 8 h in bioreactors, presenting an increased expression of the co-stimulatory molecules and also high levels of Th1 related cytokines. Upon just the 2nd stimulation, the T cells exhibited specificity following stimulation with the CEA/WT1 peptides and strong cytotoxic capacity in co-culture with a colorectal cancer (CRC)-cell line. The high produced doses of DCs, easily maturated with clinically approved agents, and capable of priming specific T cells, could potentially strengthen the further progress in DCs-mediated cancer immunotherapy field.