Allogeneic Tumor Cells Research Articles

Dendritic Cell-Based Immunotherapy in Patients With Resected Pancreatic Cancer.

Immunotherapies have shown limited responses in patients with advanced pancreatic cancer. Recently, we reported that dendritic cell (DC)-based immunotherapy induced T-cell responses against pancreatic cancer antigens. The primary objective of this study was to determine the efficacy of DC-based immunotherapy to prevent recurrence of disease. This was a single-center, open-label, single-arm, combined phase I/II trial. The primary end point was the 2-year recurrence-free survival (RFS) rate. A 2-year RFS rate of ≥60% was defined as a clinically meaningful improvement. We included patients with pancreatic cancer after resection and completion of standard-of-care (SOC) treatment without recurrent disease on cross-sectional imaging. Patients were treated with autologous DCs pulsed with an allogeneic mesothelioma tumor cell lysate, comprising antigens also expressed in pancreatic ductal adenocarcinoma. Thirty-eight patients were included in the analysis of the primary end point (47% male, 53% female). The median age was 62 years (IQR, 55-68). Twenty-eight patients (74%) received five DC vaccinations and completed the study protocol. Three patients (8%) received four vaccinations, and seven patients (16%) received three vaccinations. After a median follow-up of 25.5 months, 26 patients (68%) had not developed recurrence of disease. The estimated 2-year RFS was 64%. Vaccination led to the enrichment of circulating activated CD4+ T cells and the detection of treatment-induced immune responses in vitro. T-cell receptor-sequencing analyses of a resected solitary lung metastasis showed influx of vaccine-specific T cells. This study reached its primary end point of a 2-year RFS rate of ≥60% following pancreatectomy after SOC treatment and adjuvant DC-based immunotherapy in patients with pancreatic cancer. These results warrant a future randomized trial.

Dendritic cells loaded with allogeneic tumour cell lysate plus best supportive care versus best supportive care alone in patients with pleural mesothelioma as maintenance therapy after chemotherapy (DENIM): a multicentre, open-label, randomised, phase 2/3 study

Dendritic cell immunotherapy has proven to be safe and induces an immune response in humans. We aimed to establish the efficacy of dendritic cells loaded with allogeneic tumour cell lysate (MesoPher, Amphera BV, 's-Hertogenbosch, Netherlands) as maintenance therapy in patients with pleural mesothelioma. In this open-label, randomised, phase 2/3 study, patients with histologically confirmed unresectable pleural mesothelioma, aged 18 years or older, with an Eastern Cooperative Oncology Group performance status score of 0-1, and non-progressing disease after four to six cycles of standard chemotherapy (with pemetrexed 500 mg/m2 plus platinum [cisplatin 75 mg/m2 or carboplatin area under the curve of 5]) were recruited from four centres in Belgium, France, and The Netherlands. Participants were randomly assigned (1:1), using block randomisation (block size of 4), stratified by centre and histology (epithelioid vs other), to MesoPher treatment plus best supportive care or best supportive care alone. Patients received up to a maximum of five MesoPher infusions, with treatment administered on days 1, 15, and 29, and weeks 18 and 30. At each timepoint, participants received an injection of 25 × 106 dendritic cells (two-thirds of the dendritic cells were administered intravenously and a third were injected intradermally). Best supportive care was per local institutional standards. The primary endpoint was overall survival, assessed in all participants randomly assigned to treatment (full analysis set) and safety assessed in all randomly assigned participants, and who underwent leukapheresis if they were in the MesoPher group. This study is registered with ClinicalTrials.gov, NCT03610360, and is closed for accrual. Between June 21, 2018, and June 10, 2021, 176 patients were screened and randomly assigned to the MesoPher group (n=88) or best supportive care alone group (n=88). One participant in the MesoPher group did not undergo leukapheresis. Mean age was 68 years (SD 8), 149 (85%) of 176 were male, 27 (15%) were female, 173 (98%) were White, two were Asian (1%), and one (1%) was other race. As of data cutoff (June 24, 2023), after a median follow up of 15·1 months (IQR 9·5-22·4), median overall survival was 16·8 months (95% CI 12·4-20·3; 61 [69%] of 88 died) in the MesoPher group and 18·3 months (14·3-21·9; 59 [67%] of 88 died) in the best supportive care group (hazard ratio 1·10 [95% CI 0·77-1·57]; log-rank p=0·62). The most common grade 3-4 treatment-emergent adverse events were chest pain (three [3%] of 87 in the MesoPher group vs two [2%] of 88 in the best supportive care group), dyspnoea (none vs two [2%]), anaemia (two [2%] vs none), nausea (none vs two [2%]), and pneumonia (none vs two [2%]). No deaths due to treatment-emergent adverse events were recorded. Treatment-related adverse events consisted of infusion-related reactions (fever, chills, and fatigue), which occurred in 64 (74%) of 87 patients in the MesoPher group, and injection-site reactions (itch, erythema, and induration), which occurred in 73 (84%) patients, and all were grade 1-2 in severity. No deaths were determined to be treatment related. MesoPher did not show improvement in overall survival in patients with pleural mesothelioma. Immune checkpoint therapy is now standard of care in pleural mesothelioma. Further randomised studies are needed of combinations of MesoPher and immune checkpoint therapy, which might increase efficacy without adding major toxicities. Amphera BV and EU HORIZON.

In vitro cell killing proficiency of autologous immune cells educated with allogenic multi-cancer tumor cell lysate.

e14675 Background: Allogenic tumor lysate therapies offer a novel approach in oncology, to initiate a measured immune system response to combat cancer. Loaded with tumor antigens, these lysates stimulate the patient's immune system for targeted cancer cell destruction. In vitro data suggesting efficacy is pivotal prior to clinical trials. Per-C-Vax is a novel, organ-agnostic, allogenic tumor lysate immuno-stimulant, and is intended to target solid organ malignancies via subcutaneous injection. It is derived from a multi-organ cell-line cocktail, which has been induced into apoptosis to capture diverse Tumor Associated Molecular Patterns (TAMPs) and Damage Associated Molecular Patterns (DAMPs). Our study assesses Per-C-Vax-educated patient-specific immunocytes' in-vitro cell-killing activity against their autologous tumor cells. Methods: We collected simultaneous blood and tumor tissue samples from 22 patients with solid organ tumors under approved protocols. The cohort included 10 head and neck (45%), 4 breast (18%), and 8 other cancers (36%) comprising colorectal, ovary, lung, gallbladder, prostate, uterine, cervix, and gastric cancers. Peripheral Blood Mononuclear Cells (PBMCs) from a 10 ml venous draw were split into control and Per-C-Vax incubated aliquots for each patient. Approximately 1,000 tumor cells, stained with Calcein AM, were co-cultured with about 20,000 cells from each of the Per-C-Vax and control PBMC aliquots (autologous). Imaging-based pre- and post-co-culture counts determined the cell-kill rate for each aliquot. Results: PBMCs not treated with Per C Vax showed a significantly reduced cancer cell killing activity against autologous tumor cells compared to Per-C-Vax -treated PBMCs, suggesting the tolerogenic characteristic of immunocytes to the malignancy (0%-32%, 95% CI 10.16 to 16.65). On the other hand, PBMCs treated with Per-C-Vax showed significant cell-kill activity ranging from 46% to 84% in head and neck (mean 62.1%, 95% CI 52.67 to 71.53), 51% to 73% in breast (mean 62%, 95% CI 44.33 to 79.67), 38% to 87% in other cancers (colorectal, ovary, lung, gallbladder, prostate, uterine, cervix, gastric) (mean 50.87%, 95% CI 37.71 to 64.04). A comparative analysis between the untreated group and the group treated with Per-C-Vax revealed a statistically significant result with a p-value <0.005. Conclusions: Patient-specific PBMCs incubated with Per-C-Vax tumor lysate immuno-stimulant show significant autologous cancer cell killing activity against multiple cancers in vitro. Human trials to establish safety and efficacy are planned.

Abstract CT134: Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma

Abstract Background: Strategies are needed to improve effectiveness of immunotherapy in pancreatic ductal adenocarcinoma (PDA). Our recently published study (NCT02648282) showed that increased M1/M2 ratio and decreased PDL1+ M2-like tumor associated macrophages (TAM) in locally advanced PDA is associated with longer overall survival (OS) following combination of stereotactic body radiotherapy, GVAX and anti-PD1 antibody pembrolizumab (Pem). We hypothesized targeting M2-like macrophages, regulated by the colony stimulating factor-1 (CSF1) pathway, would improve outcomes. In this pilot study we investigated the safety and intratumoral immune response of neoadjuvant/adjuvant triplet immunotherapy: GVAX/cyclophosphamide (CY), Pem, and CSF1 receptor blockade (IMC-CS4) in patients with resectable or borderline resectable PDA. Methods: After completing chemotherapy and radiation patients received two 3-week cycles of neoadjuvant triplet immunotherapy. Following surgery, patients received 4 additional cycles followed by booster Pem every 3 weeks and GVAX/CY every 6 months, for one year. Co-primary endpoints were safety, assessed by NCI Common Terminology Criteria for Adverse Events (AEs), and immune response (increased CD8+ T-cell density in surgical specimen as compared to pre-treatment core). Secondary endpoints included disease free survival (DFS), OS, surgical resectability, and pathologic response (PR). Results: Nine patients were enrolled. Two immune related grade 3/4 AEs (diarrhea and rash) were reported. Median DFS was 12.6 months (95% CI: 7.3, NR) and median OS was 20.4 months (95% CI: 17.5, NR). All patients underwent surgery with major PR rate of 78% (defined as <10% residual viable tumor), including one complete PR. Comparing paired biopsies, the study met its primary immunologic endpoint showing 6/8 patients (75%) had a >80% increase of CD8+ T cells; the increase was at least 1.8 times the baseline median absolute deviation following triple therapy (p=0.012). There was a significant increase of Granzyme B+ CD8+ T cells among all patients (p=0.045). No significant change in myeloid cell density, including TAM, was observed, suggesting IMC-CS4 did not deplete macrophages, but potentially reprogrammed them. The 4 patients with greatest drop in CD66b+ granulocyte levels had major PR (grade 0 or 1). Conclusion: The triplet was safe and significantly increased activated CD8+ T cells suggesting the combination can induce an effector T cell response. Decreased granulocyte levels correlated with PR. Citation Format: Arielle Urman, Yingjun Ding, Hao Wang, Richard A. Burkhart, Jin He, Elizabeth M. Jaffee, Amol K. Narang, Dung Le, Daniel A. Laheru, Lei Zheng, Ana De Jesus-Acosta. Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT134.

Abstract 6750: Validation of a platform to develop new dendritic cell vaccines for cancer immunotherapy

Abstract Osteosarcoma is the most common malignant form of bone cancer that generally causes patients to die of pulmonary metastasis. If detected before the tumor has metastasized, osteosarcoma has a 75% survival at 5 years after the conventional therapy with surgery and chemotherapy. However, most osteosarcomas are high-grade tumors that grow quickly and spread before being detected, lowering patient survival to 20%. Our unique protocol using the human platelet lysate PLTMax® allows establishing tumor cell lines without genetically modifying cells and with minimal genetic drift. The use of PLTMax® and allogeneic tumor cell cultures has proven to be a major advantage for the generation of large amounts of rich tumor antigen libraries for dendritic cell (DC) vaccines. This protocol was used in an autologous dendritic cell/allogeneic tumor lysate vaccine developed at the Mayo Clinic and licensed to Mill Creek Life Sciences (MCLS) to treat newly diagnosed glioblastoma (GBM), which normally has a poor survival rate at only 2%. The technology was used in a phase I clinical trial (MC1272) performed at the Mayo Clinic. The clinical outcomes proved over a 10 time increase in survival rate of patients that received the DC vaccine after the conventional therapy, providing over 20% three-year survival rate. Our technology differs from other clinically used DC vaccines in three primary ways: a) Highly efficient cell line establishment: The unique method for generating tumor cell lines uses Mill Creek Life Sciences’ PLTMax®, a media supplement derived from human platelets. PLTMax® more closely mimics the native microenvironment of tumors and is used to reduce genetic drift and senescence. b) High genetic fidelity: GBM tumor cells expanded via PLTMax® maintain genetic fidelity and TAA expression—a feat that has not been previously achieved by any other GBM cell culture method. c) Reduction of treatment delays and inclusion of all patients that qualify for treatment: Because we will use allogeneic tumor cell lines, we will be able to avoid delays in treatment caused by the time required to culture autologous tumor cell lines, and all patients may receive treatment without exclusion. Through our preliminary work we transferred the technology from a labor-intensive, small-scale approach, to an automated scalable system. Our ultimate goal is to apply this strategy to not only osteosarcoma, but also several other tumor types to validate it as a platform. Like osteosarcoma, there are other therapy-refractory cancers that we believe can benefit from the use of our platform technology, through the use of DC vaccines that offer an immune response against a wider panel of tumor antigens. Citation Format: Vanesa Alonso-Camino, William Mirsch. Validation of a platform to develop new dendritic cell vaccines for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6750.

Abstract 4124: Patient-derived ex vivo models to test drug responses of disseminated cancer cells in various metastatic niches

Abstract Metastases arise from disseminated cancer cells (DCCs) that often lodge to distant organs long before diagnosis of the primary tumor. Unfortunately, the efficacy of (neo-)adjuvant therapies against DCCs remains uncertain. Here, we harnessed novel patient-derived ex vivo models to identify promising candidate therapies targeting DCCs and explored the impact of the unique microenvironment of metastatic target organs on the phenotypes and drug responses of DCCs. We screened disaggregated lymph node (LN) or bone marrow (BM) samples from melanoma, breast, and bladder cancer patients without distant metastasis for the presence of DCCs. Then, we expanded DCCs in patient-derived xenografts, adherent cell culture, or three-dimensional culture. LN and BM suspensions were spiked with allogeneic and autologous tumor cells to unravel the impact of different metastatic niches on DCCs. Automated high-throughput microscopy of disaggregated patient LNs was used to evaluate drug effects on DCCs in the autologous microenvironment. We established 13 cell lines from melanoma DCCs, three organoid models from breast cancer DCCs, and two organoid models from bladder cancer DCCs. The origin of each model was confirmed by assessment of histomorphology, marker expression, and genetic profiles. We screened a comprehensive panel of chemotherapeutics, targeted drugs, and antibody-drug conjugates across these in vitro models, and thereby identified compounds with the potential to eradicate DCCs. We further found that the LN and BM microenvironments differentially affected phenotypes and drug responses of cancer cells particularly when immune modulating drugs were used. Of note, ex vivo drug testing, performed directly on LN suspensions containing DCCs, revealed candidate therapeutics within a time frame acceptable for personalized treatment decisions. In conclusion, we report that the microenvironment of the specific metastatic niche impacts DCC drug responsiveness. Employing DCC-derived in vitro models in drug response assays that include specific niches may help to develop (neo)-adjuvant, personalized therapies and to discover novel therapeutics against metastasis. Citation Format: Lukas Wöhrl, Catherine Botteron, Kathrin Weidele, Steffi Treitschke, Durdam Das, Melanie Werner-Klein, Martin Hoffmann, Nataša Stojanović Gužvić, Silvia Materna-Reichelt, Florian Weber, Simon Engelmann, Roman Mayr, Miodrag Gužvić, Sebastian Haferkamp, Stephan Seitz, Christoph A. Klein, Christian Werno. Patient-derived ex vivo models to test drug responses of disseminated cancer cells in various metastatic niches [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4124.

Allogeneic "Zombie Cell" as Off-The-Shelf Vaccine for Postsurgical Cancer Immunotherapy.

Allogeneic tumor cell vaccines provide off-the-shelf convenience but lack patient specificity due to heterogeneity in tumor antigens. Here, allogeneic tumor cell corpses are converted into "zombie cells" capable of assimilating heterogeneous tumor by seizing cancer cells and spreading adjuvant infection. This causes pseudo-oncolysis of tumors, transforming them into immunogenic targets for enhanced phagocytosis. It is shown that in postoperative tumor models, localized delivery of premade "zombie cells" through stepwise gelation in resection cavity consolidates tumor surgery. Compared to analogous vaccines lacking "seizing" or "assimilating" capability, "zombie cell" platform effectively mobilizes T cell response against residual tumors, and establishes immunological memory against tumor re-challenge, showing less susceptibility to immune evasion. Despite using allogeneic sources, "zombie cell" platform functions as generalizable framework to produce long-term antitumor immunity in different tumor models, showing comparable effect to autologous vaccine. Together, with the potential of off-the-shelf availability and personalized relevance to heterogenous tumor antigens, this study suggests an alternative strategy for timely therapy after tumor surgery.

Adjuvant Vaccination with Allogenic Dendritic Cells Significantly Prolongs Overall Survival in High-Grade Gliomas: Results of a Phase II Trial

Immunotherapy for cancer treatment has gained increased attention in recent years. Recently, our group reported the case of a patient with glioblastoma who underwent vaccination based on dendritic cells and experienced a strong Th1 immune response together with near-complete tumor remission. Here we report the results of a phase I/II prospective, non-controlled clinical trial with 37 patients harboring glioblastoma or grade 4 astrocytomas. At the time of first recurrence after surgery, patients began receiving monthly intradermal injections of allogenic DC-autologous tumor cell hybridomas. Overall survival, quality of life, and immunological profiles were assessed prospectively. Compared with patients in the Genomic Data Commons data bank, overall survival for vaccinated patients with glioblastoma was 27.6 ± 2.4 months (vs. 16.3 ± 0.7, log-rank p < 0.001, hazard ratio 0.53, 95%CI 0.36-0.78, p < 0.01), and it was 59.5 ± 15.9 for vaccinated astrocytoma grade 4 patients (vs. 19.8 ± 2.5, log-rank p < 0.05, hazard ratio 0.18, 95%CI 0.05-0.62, p < 0.01). Furthermore, seven vaccinated patients (two IDH-1-mutated and five wild type) remain alive at the time of this report (overall survival 47.9 months, SD 21.1, range: 25.4-78.6 months since diagnosis; and 34.2 months since recurrence, range: 17.8 to 40.7, SD 21.3). We believe that the data reported here can foster the improvement of treatment protocols for high-grade gliomas based on cellular immunotherapy.

Combined immunotherapy and radiation induce cellular and humoral immune responses to tumor-associated antigens and prolong survival of patients with advanced cancers.

Immunotherapy is effective in treating patients with a variety of cancers We developed and employed an immunotherapeutic protocol that combined intra-tumor injection of autologous immature dendritic cells , with standard of care radiation to treat patients with a variety of different advanced solid tumors. Pre and post treatment peripheral blood mononuclear cells ( PBMC) were assayed for their capacity to kill autologous tumor cell lines that had been established from patients with different advanced solid tumors. PBMC obtained post treatment were cytotoxic to autologous but not allogeneic tumor cell lines. Cytotoxic activity increased as relative numbers of CD8+-CD56+ dual positive lymphoid cells increased in PBMC obtained post treatment. The autologous tumor cell line directed cytotoxicity was shown to be mediated by both innate and adaptive immune mechanisms. Cytotoxicity of PBMC obtained post treatment was enhanced after co-culture with autologous and not allogeneic tumor cell line lysates. Antibody activity to mesothelin, a tumor associated antigen expressed in a variety of solid tumors, increased in post treatment serum samples from lung cancer patients. These sera mediated antibody directed cellular cytotoxicity ( ADCC) to mesothelin expressing tumor cell lines. SSurvival of 96 patients with a variety advanced cancers patients treated on this protocol over a 3 year period and followed for 1000+ days was significantly increased in patients with low tumor burden ( lesion at &lt;5 sites with diameters &lt; 3cm) (Km= &lt;0.0001) regardless of malignancy. These findings support application of this combination of immunotherapy and radiation in the treatment of cancer patients with advanced disease

The therapeutic effect of an autologous and allogenic mixed glioma cell lysate vaccine in a rat model.

Tumor immunotherapy has the advantages of high specificity, minimal damage to the patient's body, and a long-lasting anti-tumor effect. However, due to the existence of immune escape phenomenon, the effect of anti-tumor immunotherapy is still poor. Therefore, a cancer vaccine that reverses tumor-associated immunosuppression is a very promising approach for research and treatment. Vaccines were prepared using autologous and allogeneic tumor cells and their lysates to syngeneic tumor cell lysates as immunogens. The glioma cell proliferation, apoptosis and the secretion level of MCP-2, IFN-γ were detected to evaluate the efficacy of this treatment against glioma in vitro. In addition, a rat glioma model was established to investigate the anti-tumor effect in vivo, and evaluated its efficacy by observing the changes of CD4 + T cells, CD8 + T cells, NK cells, and the level of IL-2 and IL-10 in peripheral blood before and after treatment. The C6 + 9L glioma cell lysate vaccine (C6 + 9L-CL) not only inhibited the proliferation of glioma cells and promoted their apoptosis in vitro, but also significantly inhibited the tumor growth in vivo and improved the survival time of rats. In addition, the C6 + 9L-CL vaccine enhanced the anti-tumor immune response by promoting the secretion of T cell chemokines MCP-2, IFN-γ and IL-2, and by stimulating the proliferation of T cells and NK cells in peripheral blood and glioma tissues. Our findings demonstrate the inhibitory effect of molecular mimic vaccines on glioma and provided a theoretical basis for molecular mimic hybrid vaccines as a potential therapeutic approach.

A Prospective, Cohort Study of SITOIGANAP to Treat Glioblastoma When Given in Combination With Granulocyte-Macrophage Colony-Stimulating Factor/Cyclophosphamide/Bevacizumab/Nivolumab or Granulocyte-Macrophage Colony-Stimulating Factor/Cyclophosphamide/Bevacizumab/Pembrolizumab in Patients Who Failed Prior Treatment With Surgical Resection, Radiation, and Temozolomide

BackgroundGlioblastoma (GBM) is the most common primary, malignant brain tumor in adults and has a poor prognosis. The median progression-free survival (mPFS) of newly diagnosed GBM is approximately 6 months. The recurrence rate approaches 100%, and the case-fatality ratio approaches one. Half the patients die within 8 months of recurrence, and 5-year survival is less than 10%. Advances in treatment options are urgently needed. We report on the efficacy and safety of a therapeutic vaccine (SITOIGANAP: Epitopoietic Research Corporation) administered to 21 patients with recurrent GBM (rGBM) under a Right-to-Try/Expanded Access program. SITOIGANAP is composed of both autologous and allogeneic tumor cells and lysates.MethodsTwenty-one patients with rGBM received SITOIGANAP on 28-day cycles in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), cyclophosphamide, bevacizumab, and an anti-programmed cell death protein-1 (anti-PD-1) monoclonal antibody (either nivolumab or pembrolizumab).ResultsThe mPFS was 9.14 months, and the median overall survival (mOS) was 19.63 months from protocol entry. Currently, 14 patients (67%) are at least 6 months past their first SITOIGANAP cycle; 10 patients (48%) have received at least six cycles and have a mOS of 30.64 months and 1-year survival of 90%. The enrollment and end-of-study CD3+/CD4+ T-lymphocyte counts strongly correlate with OS.ConclusionsThe addition of SITOIGANAP/GM-CSF/cyclophosphamide to bevacizumab and an anti-PD-1 monoclonal antibody resulted in a significant survival benefit compared to historic control values in rGBM with minimal toxicity compared to current therapy.

Abstract 3151: A novel method to produce clinical scale induced pluripotent stem cell-derived natural killer (iPSC-NK) cells with improved anti-tumor activity for next-generation allogenic cell therapies

Abstract Natural killer (NK) cells are innate immune cells that play a key role in tumor immune surveillance. NK cells have self-tolerance to healthy cells and can kill allogeneic tumor cells- both hematological and solid malignancies. Recent advances to derive immune cells from human induced pluripotent stem cells (iPSCs) allow the production of NK cells that can be used for immunotherapy. Recent clinical trials suggest that high doses of NK cells (approx. 0.5-1 x 109 cells per dose) and multiple doses are both safe and likely necessary for clinical efficacy. Manufacturing large number of NK cells from a clonal master iPSC line provides a promising strategy to enable off-the-shelf, next generation allogenic cell therapies. To do this, we have developed a novel method to produce clinical scale iPSC-NK cells and improved the process to expand NK cells efficiently and consistently. Briefly, hematopoietic progenitor cells were induced using an improved spin embryoid body (EB) method and the hematopoietic progenitor cells were subsequently differentiated into mature NK cells without cell sorting step as well as stroma cells support. Using this novel protocol, differentiated NK cells expanded more than 3,000-fold to enable us to potentially produce 1 x 1012 iPSC-NK cells starting from 1 x 106 undifferentiated iPSC. This cell production scale can supply &amp;gt;200 doses of 109 cells per dose. Importantly, iPSC-NK cells produced using this method display the typical phenotype of NK cell activating receptor including NKG2D, NKp44, NKp46, and DNAM-1. These iPSC-NK cells demonstrate better anti-tumor activity (against AML) and higher levels of IFNγ and TNFα compared to primary peripheral blood-derived NK cells isolated from healthy donors. Additionally, our iPSC-NK cells demonstrated prolonged “serial killing” of AML cells up to six days. Moreover, this protocol has been tested in large scale using not only unmodified iPSC-NK cells, but also genetically engineered iPSC-NK cells including those with deletion of CISH in iPSC-derived NK cells us that demonstrate improved in vivo anti-tumor activity, in vivo persistence, metabolic fitness, polyfunctionality and resistance to cell exhaustion to create next-generation CAR-NK cell-based immunotherapies. Overall, this novel cell production strategy paves the way for clinical trials using higher doses of more potent iPSC-derived NK cells. Citation Format: Davide Bernareggi, Caryn Gonsalves, Max Schabla, Alejandra Garate-Carrilo, Eleanor O’Gorman, Nathan Chang, Luis Solchaga, Mohammad El-Kalay, William Sandborn, Dan S. Kaufman, Huang Zhu. A novel method to produce clinical scale induced pluripotent stem cell-derived natural killer (iPSC-NK) cells with improved anti-tumor activity for next-generation allogenic cell therapies [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 3151.

Autologous dendritic cells pulsed with allogeneic tumour cell lysate induce tumour-reactive T-cell responses in patients with pancreatic cancer: A phase I study

BackgroundPancreatic ductal adenocarcinoma (PDAC) is notorious for its poor prognosis even after curative resection. Responses to immunotherapy are rare and related to inadequate T-cell priming. We previously demonstrated the potency of allogeneic lysate-dendritic cell (DC) vaccination in a preclinical model. Here we translate this concept to patients. MethodsIn this phase I study, patients with resected PDAC were included when they demonstrated no radiologic signs of recurrence after standard-of-care treatment. Allogeneic tumour lysate-loaded autologous monocyte-derived DCs were injected at weeks 0, 2, 4 and at months 3 and 6. Objectives are feasibility, safety and immunogenicity of allogeneic tumour-DCs. The presence of tumour antigens shared between the vaccine and patient tumours was investigated. Immunological analyses were performed on peripheral blood, skin and tumour. ResultsTen patients were included. DC production and administration were successful. All patients experienced a grade 1 injection-site and infusion-related reaction. Two patients experienced a grade 2 fever and 1 patient experienced a grade 3 dyspnoea. No vaccine-related serious adverse events were observed. Shared tumour antigens were found between the vaccine and patient tumours. All evaluated patients displayed a vaccine-induced response indicated by increased frequencies of Ki67+ and activated PD-1+ circulating T-cells. In addition, treatment-induced T-cell reactivity to autologous tumour of study patients was detected. Seven out of ten patients have not experienced disease recurrence or progression at a median follow-up of 25 months (15–32 months). ConclusionAllogeneic tumour lysate-DC treatment is feasible, safe and induces immune reactivity to PDAC expressed antigens.

Neoadjuvant and adjuvant antitumor vaccination alone or combination with PD1 blockade and CD137 agonism in patients with resectable pancreatic adenocarcinoma.

558 Background: Utilizing a vaccine that induces and activates host effector T cells and co-administering it with immune modulating agents that enhance anti-tumor T cell activity is a potential strategy for overcoming pancreatic adenocarcinoma’s (PDA) resistance to immunotherapy. Our prior clinical trial demonstrated a GM-CSF-secreting, allogeneic tumor cell vaccine (GVAX) increases infiltrating CD8+ T cells in PDA. Follow up preclinical work demonstrated therapeutic synergy between GVAX and PD-1inhibition (PD1) with efficacy further enhanced by CD137 agonism (CD137). Methods: This was a 3-arm trial of neoadjuvant &amp; adjuvant GVAX-based therapy in resectable (r) PDA patients (pts). Adults with clinically resectable, untreated PDA were enrolled in 1 of 3 study treatments: Arm A (GVAX alone), Arm B (GVAX + PD1 [Nivolumab]), or arm C (GVAX + PD1 + CD137 [Urelumab]). Treatment was given as follows: Day 1 - Cyclophosphamide 200mg/m2 IV (All Arms), Nivolumab 480mg IV (Arms B, C), Urelumab 8mg IV (Arm C); Day 2 – GVAX ID (All Arms). Pts were treated at 3 timepoints: 1) once 2 weeks prior to surgery; 2) once post-surgical recovery prior to standard of care adjuvant chemotherapy (SOC); 3) every month (up to 4 mo) following completion of SOC (if disease-free). SOC regimes included (m)FOLFIRINOX, Gem +/- Cap/NAB-Paclitaxel. The study was powered for a primary biologic endpoint: treatment-related change in intratumoral CD8+CD137+ T cells. Clinical endpoints included disease-free survival (DFS: time from surgery to recurrence), overall survival (OS: time from surgery to death), and safety. Results: 38 pts (N = 15 [Arm A], N = 13 [Arm B], N = 10 [Arm C]) were eligible for efficacy analysis (had R0/R1 resection) and 45 pts (N = 17 [A], N = 17 [B], N = 11 [C]) were eligible for safety analysis (had ≥1 dose of study treatment). Demographics, surgical pathology features, and SOC durations were similar in all Arms. At median follow up of 23 mo [A], 26 mo [B], and 22 mo [C], median DFS (95% CI) was 14.82 mo (6.0, NA), 16.23 mo (7.49, NA) and not reached (16.33, NA) for Arms A, B, C, respectively. There was no DFS benefit to adding PD1 compared to GVAX alone (HR 0.98 [95% CI 0.42, 2.27], p = 0.96). Combination CD137 + PD1 + GVAX was associated with marginally significant improved DFS compared to GVAX alone (HR 0.38 [95%CI 0.12, 1.19], p = 0.097) and GVAX + PD1 (HR 0.38 [95%CI 0.12, 1.21], p = 0.103). Median OS (95% CI) was 25.0 mo (18.8, NA), 26.4 mo (20.3, NA), and not yet reached for Arms A, B, C, respectively. There were no serious adverse events. In Arm C, 1 pt had grade 3 rash that delayed treatment and there was 1 instance of grade 2 AST/ALT elevation. The biologic endpoint will be reported at the meeting. Conclusions: Despite a small sample size, combining GVAX with dual immune-targeting of PD-1 blockade and CD137 agonism was safe and may enhance DFS in rPDA pts treated in the perioperative and post-adjuvant settings. Clinical trial information: NCT02451982.

Phase I trial of adjuvant mature autologous dendritic cell/allogeneic tumor lysate vaccines in combination with temozolomide in newly diagnosed glioblastoma.

BackgroundGlioblastoma (GBM) has poor prognosis despite aggressive treatment. Dendritic cell (DC) vaccines are promising, but widespread clinical use has not been achieved, possibly reflecting manufacturing issues of antigen choice and DC potency. We previously optimized vaccine manufacture utilizing allogeneic human GBM tumor cell lysate and potent, mature autologous DCs. Here, we report a phase I study using this optimized DC vaccine in combination with standard therapy.MethodsFollowing surgical resection and radiation with concurrent temozolomide (TMZ), newly diagnosed adult GBM patients received intradermal DC vaccines plus TMZ. Primary endpoints were safety and feasibility. Immune and treatment responses were recorded.ResultsTwenty-one patients were enrolled in this study. One progressed between leukapheresis and vaccine manufacture. Twenty patients received treatment per protocol. Vaccine doses (≥15) were generated following a single leukapheresis for each patient. No dose-limiting vaccine toxicities were encountered. One patient had symptomatic, histologically proven pseudoprogression. Median progression-free survival was 9.7 months. Median overall survival was 19 months. Overall survival was 25% at 2 years and 10% at 4 years. One patient remains progression-free 5 years after enrollment. Specific CD8 T-cell responses for the tumor-associated antigen gp100 were seen post-vaccination. Patients entered the trial with a leukocyte deficit compared to healthy donors which partly normalized over the course of therapy.ConclusionsThis vaccine platform is safe and highly feasible in combination with standard therapy for newly diagnosed patients. Imaging, histological, survival, and immunological data suggest a positive biological response to therapy that warrants further investigation.

Allogeneic tumor cell line-based vaccines: A good alternative to autologous and cancer stem cell vaccines in colorectal cancer.

Objective(s):Besides the uncertainty about colorectal cancer stem cell (CCSC) markers, isolating, purifying, and enriching CCSCs to produce CCSC vaccines is highly challenging. However, allogeneic vaccines developed from CRC cell lines can provide universal, comprehensive, inexpensive, simple, and fast approach to cancer treatment. Materials and Methods:CCSCs were isolated from human CRC tissue using the in vitro sphere formation assay and then characterized through gene expression analysis, in vivo and in vitro tumor formation assay, karyotyping, and surface marker detection. Subsequently, CCSCs and two CRC cell lines (HT-29 and SW-480) were inactivated with cisplatin (CDDP) and administrated as vaccines to the three groups of athymic C57BL/6 nude mice. Afterward, tumorigenesis was challenged with HT-29 cells. The antitumor effect of vaccines was evaluated by tumor and spleen examination and immune response analysis. The cytotoxic activity of splenocytes and serum levels of TGF-β and IFN-γ were measured by Calcein-AM cytotoxicity assay and enzyme-linked immunosorbent assay (ELISA), respectively.Results:The results of gene expression analysis showed that CCSCs are CD44+CD133-LGR5-. All vaccinations resulted in decreased tumor growth, spleen enlargement, enhanced serum level of IFN-γ and TGF-β, and increased cytotoxic activity of natural killer (NK) cells. The antitumor efficacy of the CCSC vaccine was not more than CRC cell line-based vaccines. Interestingly, the allogeneic SW-480 vaccine could effectively inhibit tumorigenesis.Conclusion:Despite the great challenge in developing CCSC vaccines, allogeneic vaccines based on CRC cell lines can efficiently induce antitumor immunity in CRC.

A Bayesian network meta-analysis of comparison of cancer therapeutic vaccines for melanoma.

Several approaches to active immunotherapy for melanoma, including peptide‐based vaccines (PVs), autologous tumour cell vaccines (TCVs), allogeneic TCVs and autologous dendritic cell vaccines (DCVs), have been investigated in clinical trials. However, comprehensive evidence comparing these interventions remains unavailable. The objective of this study was to expand previous work to compare and rank the immunotherapeutic strategies for melanoma in terms of overall survival and toxic effects with a Bayesian network meta‐analysis. Methodologically, we performed a network meta‐analysis of head‐to‐head randomized controlled trials comparing and ranking cancer vaccine approaches for patients with melanoma. PubMed, MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, the WHO International Clinical Trials Registry Platform and ClinicalTrials.gov were searched up to 31 July 2020. We estimated summary hazard ratios for death and risk ratios for toxicity. The effects of the underlying prognostic variable on survival benefits were examined by meta‐regression. We performed subgroup analysis for the outcomes based on metastatic categories. Overall, we identified 4776 citations, of which 15 head‐to‐head randomized controlled trials (3162 participants) were included in the analysis. In terms of efficacy, allogeneic tumour cell vaccines plus immunotherapy adjuvants, peptide‐based vaccines plus immunotherapy adjuvants and standard therapy were more effective than peptide vaccines. The proportion of women was inversely associated with mortality risk. For safety, all treatments were inferior to allogeneic tumour cell vaccines except for allogeneic tumour cell vaccines plus chemotherapy. Peptide vaccines plus immunotherapy adjuvants led to an increased risk of adverse events compared to allogeneic tumour cell vaccines plus immunotherapy adjuvants. These results suggest that allogeneic TCV and autologous DCV are better than standard therapy. PV plus immune modulators are the most effective strategy among all comparable strategies but is associated with increased toxicity. Any combination regimens for cancer therapeutic vaccines need to be balanced between risk and benefit profiles.

Whole tumor cell vaccines engineered to secrete GM‐CSF (GVAX)

AbstractGeneration of immunity against cancer through vaccination has long been an elusive goal for tumor immunologists. Putative candidates for vaccination targets include oncofetal antigens, viral antigens, neoantigens, and differentiation antigens. The first attempts at cancer vaccination used injections of whole autologous tumor cells. However, these unmodified tumor cells did not engender a robust immune response. Subsequent efforts were focused at enhancing the immunogenicity of whole autologous tumor cell vaccines through genetic modification, often through virally mediated transduction of genes encoding immunostimulatory molecules. Of many immunostimulatory cytokines evaluated in the context of gene‐modified tumor cell vaccines, granulocyte–macrophage colony‐stimulating factor (GM‐CSF) emerged as the most potent in generating protective antitumor immunity. Vaccination using irradiated, GM‐CSF producing tumor cells (GVAX) consistently induced antitumor immunity across several experimental tumor models. The term GVAX can connote GM‐CSF secreting cell vaccines prepared with different vectors as well as vector targets including autologous tumor cells, allogeneic tumor cell lines, and bystander third party tumor cells lines. GVAX has been evaluated against solid tumors, hematologic malignancies, and in the context of hematopoietic stem cell transplantation. GVAX has been extensively studied in clinical trials, both alone and in conjunction with lymphodepleting chemotherapy, immune checkpoint inhibitors, and other vaccines.

Long-Term Follow-Up of Mesothelioma Patients Treated with Dendritic Cell Therapy in Three Phase I/II Trials.

Background: Malignant pleural mesothelioma (MPM) is a fatal neoplasm with, if untreated, poor survival of approximately nine months from diagnosis. Until recently, phase II–III immunotherapy trials did not show any significant benefit. The lack of immunotherapy efficacy can be explained by the fact that mesothelioma is a tumor with an “immune desert” phenotype, meaning a non-inflamed tumor characterized by low T-cell infiltration. By administration of DCs, which were ex-vivo cultured, exposed to (tumor-associated) antigens, and subsequently activated, this “immune desert” phenotype might be turned into an “inflamed” phenotype. Three phase I/II studies have been performed and published using activated DCs, which support this concept. We here report on the long-term survival of patients treated with DCs in three phase I/II studies. Methods: Survival data of the phase I/II trials using DC therapy in MPM patients were obtained and subsequently analyzed. In the first two trials, DCs were loaded with autologous tumor lysate. In the third trial, DCs were loaded with allogeneic mesothelioma tumor cell line lysate. Results: In the three studies combined, 29 patients with MPM were treated with DC vaccination between 2006 and 2015. At data cut-off, the median OS was 27 months (95% CI: 21–47 months). OS at 2 years was 55.2% (95% CI: 39.7–76.6%), and OS at 5 years was 20.7% (95% CI: 10.1–42.2%). Conclusions: The long-term survival of DC therapy in MPM in these three trials is promising, which is the basis for the randomized phase II/III DENIM study. This DENIM study is currently enrolling, and the results of which have to be awaited for definite conclusions.

Evaluation of membrane bound IL-21 expanded natural killer cells for chronic lymphocytic leukemia therapy

Abstract Chronic lymphocytic leukemia (CLL) is the most prevalent adult leukemia and remains incurable despite recent therapeutic advances. Natural killer (NK) cells have potent anti-cancer effects, but efforts to use NK cell therapy in CLL have been limited by poor NK cell growth and anti-leukemia activity. We sought to determine if stimulating NK cells ex vivo with K562-based feeder cells expressing membrane-bound IL-21 (mbIL-21) (Denman et al., 2012) could overcome the limitations of prior techniques to create an effective therapy for CLL. Our data demonstrate that healthy donor-derived mbIL-21 expanded NK cells have increased antibody-dependent cellular cytotoxicity (ADCC) and direct cytotoxicity (DC; without targeting antibody) against CLL cell lines. This technique can also overcome CLL-induced NK suppression – CLL patient-derived NK cells expanded equally and were as potent as normal donor-derived NKs, including against both allogeneic and autologous CLL tumor cells. CLL tumor cells are not susceptible to DC but are very vulnerable to ADCC with anti-CD20 antibodies (rituximab or obinutuzumab). The lack of direct cytotoxicity of tumor cells was correlated to low NK:CLL quantitative conjugate formation, suggesting a lack of tumor target recognition. Blocking antibodies to FasL, TNFα, and TRAIL show that only TRAIL contributes modestly to anti-CLL tumor cytotoxicity, while application of folimycin demonstrates that perforin/granzyme release is the major mechanism of cytotoxicity. In vivo, treatment with expanded NK cells plus obinutuzumab significantly prolongs survival in the OSU-CLL human xenograft model. Based on these data, we are planning a clinical trial of mbIL-21 expanded NK cells plus obinutuzumab in CLL patients.