Allogeneic Vaccine Research Articles

Abstract A37: Immunization of cutaneous melanoma patients with the allogeneic cell vaccine CSF-470 enhances immune infiltration of metastatic lesions and would favor subsequent response to Vemurafenib

Abstract Therapeutic cancer vaccines are aimed at promoting tumor-specific immunity with long-term memory. We have developed the CSF-470 therapeutic vaccine, a mini-allograft of four irradiated allogeneic cutaneous melanoma cell lines, combined with BCG and rhGM-CSF as adjuvants; that is currently being assayed in adjuvancy against medium-dose IFN-alfa2b in the CASVAC-0401 phase II/III clinical trial (ClinicalTrials.gov identifier: NCT01729663). An update to September 2014 reveals that after inclusion of 31 patients, a significant benefit in the distant metastasis-free survival for the CSF-470 arm is obtained (p=0.034). Of the 20 patients assigned to the CSF-470 arm, with a mean follow-up of 26 months, six patients developed distant metastases, of whom two died, and fourteen patients are distant metastases-free (70%). Five patients of the vaccine arm were treated with Vemurafenib after progression; two of them achieved complete remission and two of them partial remission (>50%); only one developed severe dermatitis. Before Vemurafenib treatment, metastases biopsies from only three patients could be obtained; two of them later achieved complete responses. In this work, we present the analysis of the peripheral blood and in situ immune populations during CSF-470 immunization in the two patients that achieved complete responses with Vemurafenib treatment. To attain this task, histopathological characterization of tumor biopsies, along with immune populations determined by immunohistochemistry, was performed by microscopy and image analysis. Peripheral blood mononucleated cells were obtained from patients at different times during CSF-470 immunization and immune populations were assessed by flow cytometry. Patient #006 entered the CASVAC-0401 study after a primary and lymph node tumor resection. By the end of CSF-470 immunization, she developed simultaneously subcutaneous and lung metastases. Following a 3-month cycle of Vemurafenib 960mg bid, patient #006 achieved complete remission of lung tumor nodules. Analysis of immune response evolution during protocol revealed a marked increase in in situ immune infiltration at the cutaneous metastasis relative to the primary tumor, especially in CD8+, CD4+ and CD20+ cells. Several dying tumor cells could be distinguished in the cutaneous metastasis, with attached and surrounding CD8+, CD4+ and CD45Ro+ T lymphocytes and CD68+ cells; and with Granzyme B vesicles and DNA strand breaks. Patient #005 developed sequential in transit metastases; CD8+, CD4+ and CD20+ lymphocyte infiltration increased in situ in biopsies following CSF-470 immunization. Vemurafenib treatment allowed achieving a complete response characterized by brisk infiltration of CD68+ macrophages, CD11c+ dendritic cells, CD8+ and CD4+ lymphocytes. In both patients, analysis of peripheral immune populations revealed an increment of NK cells detected after 6-months treatment, followed by an increase in CD4+ and CD8+ cells by the end of the protocol (2 years). Also, serum reactivity to CSF-470 cutaneous melanoma cells increased during vaccination. We suggest that previous immunization of melanoma patients with CSF-470 vaccine increases tumor immune infiltration and subsequent response to Vemurafenib. These encouraging results may open new options for combined therapies in cutaneous melanoma. Citation Format: Mariana Aris, María Betina Pampena, Estrella M. Levy, Alicia I. Bravo, Florencia P. Madorsky-Rowdo, Ana Mordoh, Julio Kaplan, Antonela Baron, Mariela Urrutia, Paula A. Blanco, María Marcela Barrio, José Mordoh. Immunization of cutaneous melanoma patients with the allogeneic cell vaccine CSF-470 enhances immune infiltration of metastatic lesions and would favor subsequent response to Vemurafenib. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A37.

ANTICANCER EFFICACY OF ALLOGENEIC VACCINE MODIFIED WITH PROGENITOR NEURAL CELLS SUPERNATANT IN RATS WITH GLIOMA 101.8

The aim of the work was to investigate the antitumor efficacy of allogeneic tumor vaccine (ATV) modified with rat progenitor neural cell supernatant (RPNS) in rats with glioma 101.8. The study was performed on 74 white random-bred rats. ATV was developed on the basis of glioma 101.8 cell suspension modified with RPNS (0.02 or 0.10 mg/ml). RPNS was prepared from suspension made from whole rat brain tissue on 14(th) (E14) day of gestation. Model of brain glioma 101.8 was reproduced by intracerebral injection of glioma 101.8 cell suspension. ATV was injected intraperitoneally in a volume of 0.2 ml per animal once on the 10(th) day after tumor transplantation. For survival analysis Kaplan - Mayer multiple assessments method was used. Cytotoxic activity of rat lymphocytes (effector cells) was evaluated in MTT-colorimetric test by determining the state of mitochondrial dehydrogenase enzymes in target cells (allogeneic glioma 101.8 cells). Intraperitoneal administration of ATV modified with 0.10 mg/ml RPNS significantly increased mean survival time and median survival of glioma-bearing rats compared with unvaccinated group (MST (19.9 ± 2.4), 21.4 days; versus MST (14.6 ± 2.8); 14 days; p = 0.0002, Gehan's - Wilcoxon test). Intraperitoneal administration of ATV modified with 0.10 mg/ml RPNS resulted in increased cytotoxic activity of immune cells of rats with glioma in vitro compared with this index in unvaccinated group (p = 0.026, U-Mann - Whitney test). Antitumor effect of vaccination with RPNS-modified ATV is realized via increased cytotoxic activity of immune cells, what could be used for further optimization of whole tumor cell vaccine.

Regulatory requirements regarding cell-based medicinal products for human and veterinary use - a comparison

At present, there is no separate regulatory framework for cell-based medicinal products (CBMP) for veterinary use at the European or German level. Current European and national regulations exclusively apply to the corresponding medicinal products for human use. An increasing number of requests for the regulatory classification of CBMP for veterinary use, such as allogeneic stem cell preparations and dendritic cell-based autologous tumour vaccines, and a rise in scientific advice for companies developing these products, illustrate the need for adequate legislation. Currently, advice is given and decisions are made on a case-by-case basis regarding the regulatory classification and authorisation requirements.Since some of the CBMP - in particular in the area of stem-cell products - are developed in parallel for human and veterinary use, there is an urgent need to create specific legal definitions, regulations, and guidelines for these complex innovative products in the veterinary sector as well. Otherwise, there is a risk that that the current legal grey area regarding veterinary medicinal products will impede therapeutic innovations in the long run. A harmonised EU-wide approach is desirable. Currently the European legislation on veterinary medicinal products is under revision. In this context, veterinary therapeutics based on allogeneic cells and tissues will be defined and regulated. Certainly, the legal framework does not have to be as comprehensive as for human CBMP; a leaner solution is conceivable, similar to the special provisions for advanced-therapy medicinal products laid down in the German Medicines Act.

A phase III study of belagenpumatucel-L, an allogeneic tumour cell vaccine, as maintenance therapy for non-small cell lung cancer

BackgroundTreatment options after first-line chemotherapy are limited in non-small cell lung cancer (NSCLC). Belagenpumatucel-L is a therapeutic vaccine comprised of 4 transforming growth factor (TGF)-β2-antisense gene-modified, irradiated, allogeneic NSCLC cell lines that may be useful for maintenance after initial treatment. MethodsStage III/IV NSCLC patients who did not progress after platinum-based chemotherapy were randomised 1:1 to receive maintenance belagenpumatucel-L or placebo. Patients were eligible for randomisation between one and four months from the end of induction chemotherapy. The primary endpoint was overall survival. ResultsThis phase III trial enrolled 270 patients in the belagenpumatucel-L arm and 262 in the control arm. Belagenpumatucel-L was well tolerated with no serious safety concerns. There was no difference in survival between the arms (median survival 20.3 versus 17.8months with belagenpumatucel-L versus placebo, respectively; hazard ratio (HR) 0.94, p=0.594). There were also no differences in progression-free survival (4.3months versus 4.0 for belagenpumatucel-L vs placebo, respectively; HR 0.99, p=0.947). A prespecified Cox regression analysis demonstrated that the time elapsed between randomisation and the end of induction chemotherapy had a significant impact on survival (p=0.002) and that prior radiation was a positive prognostic factor (median survival 28.4months with belagenpumatucel-L versus 16.0months with placebo; HR 0.61, p=0.032). ConclusionsAlthough the overall trial did not meet its survival endpoint, improved survival for belagenpumatucel-L is suggested in patients who were randomised within 12weeks of completion of chemotherapy and in those who had received prior radiation. Further studies of belagenpumatucel-L in NSCLC are warranted.

Abstract 5037: Immunotherapy meets epigenetics: GP96-Ig cellular vaccine genetic signature is modulated by the inhibition of histone modifications

Abstract A number of novel cancer treatment strategies have been identified and developed over the last decade with hopes of eradicating a diverse range of cancers, however the molecular mechanisms behind patient immune responses and tumor microenvironment signaling are complex, and have often hindered the translation of these ideas into successful patient treatments. Two modalities at the forefront of these potential blockbuster strategies are combinatorial immunotherapy and epigenetic manipulation. These approaches are supported by compelling clinical data, but have been encumbered by a number of factors including: adverse event profiles, complicated manufacturing and regulatory issues, toxicity due to non-specific small molecule interactions, limited overlap in patient/therapy antigen presentation, and exorbitant cost of biological treatments. To circumvent a number of these limitations, we have taken a novel approach by engineering allogeneic cellular vaccines tailored to specific cancers, that secrete heat-shock protein gp96-Ig and achieve high-frequency polyclonal CD8+ T cell responses to femto-molar concentrations of tumor antigens through antigen cross-priming in vivo. Using genomics (RNA-sequencing) we identified differential mRNA expression levels genome-wide between normal bladder tissue, our proprietary bladder cancer cellular vaccine Vesigenurtacel-L or HS410, and patient bladder tumor biopsy samples, to generate a genomic signature of Bladder Cancer Altered Genes, or BCAGs. Next, we examined a number of small molecule inhibitors of epigenetic modifications (i.e. histone deacetylases or HDACs), and determined their effect on BCAG expression and antigen secretion in HS410 cells. We find that the inhibition of certain HDACs results in decreased proliferation, dampened secretion of gp96-Ig, and attenuated expression of tumor specific genes. Together our work has defined the pattern of gene dysregulation genome-wide in bladder cancer and shown that epigenetic modifiers are capable of modulating the expression of many of these genes, which may be important for the efficacy of our cancer vaccine strategy. Therefore, epigenetic manipulation may present an attractive means to fine-tune gene expression programs and maximize antigen secretion thereby increasing vaccine potency and the ability of a single vaccine to target a variety of cancer types. Citation Format: George J. Fromm, Neal Schilling, Taylor H. Schreiber. Immunotherapy meets epigenetics: GP96-Ig cellular vaccine genetic signature is modulated by the inhibition of histone modifications. [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 5037. doi:10.1158/1538-7445.AM2015-5037

222. AST-VAC2: An Embryonic Stem Cell-Derived Dendritic Cell Cancer Immunotherapy

AST-VAC2 is a cancer immunotherapy product comprising embryonic stem cell-derived dendritic cells electroporated with an mRNA encoding a telomerase/lysosome-associated membrane protein 1 (LAMP hTERT) chimeric tumor antigen. Previous studies have shown that AST-VAC2 can elicit a telomerase-specific T-cell response from partially HLA-matched donor peripheral blood mononuclear cells. A related product (AST-VAC1), an autologous dendritic cell/LAMP hTERT cancer immunotherapy, has been tested in clinical trials on patients with prostate cancer or acute myeloid leukemia. The AST-VAC1 treatment was well tolerated and generated anti-telomerase immune responses. AST-VAC2 is being developed as an off-the-shelf allogeneic cancer vaccine for clinical testing in partially HLA matched patients with non-small cell lung carcinoma. The AST-VAC2 product is derived from the H1 human embryonic stem cell line. The stem cells are differentiated into mature dendritic cells in a multi-step process via embryoid bodies, prepared growth surfaces and specific growth factors. The differentiation process requires 34 days in culture. The cells are then electroporated with the LAMP hTERT mRNA and irradiated prior to cryopreservation. In preparation for clinical testing the manufacturing process has been scaled up from T-flasks to large surface area cell stacks. This has required a number of novel process modifications including large scale embryoid body filtration and flow-through electroporation. The final product will be rendered incapable of replication by gamma irradiation. The radiation dose required for halting replication while still preserving antigen presentation was determined using a combination colony formation/potency assay. It is anticipated that the proposed Phase 1/2a clinical trial will enroll approximately 30 patients and will include both a dose escalation and a broadening of inclusion criteria to permit an assessment of safety, toxicity and immunogenicity in patients with advanced disease. Asterias has recently partnered with Cancer Research United Kingdom (CRUK) and the University of Southampton for the GMP manufacturing and initial clinical testing of AST-VAC2 in the UK.

Galectin-3 Shapes Antitumor Immune Responses by Suppressing CD8+ T Cells via LAG-3 and Inhibiting Expansion of Plasmacytoid Dendritic Cells.

Galectin-3 is a 31-kDa lectin that modulates T-cell responses through several mechanisms, including apoptosis, T-cell receptor (TCR) cross-linking, and TCR downregulation. We found that patients with pancreatic ductal adenocarcinoma (PDA) who responded to a granulocyte-macrophage colony-stimulating factor-secreting allogeneic PDA vaccine developed neutralizing antibodies to galectin-3 after immunization. We show that galectin-3 binds activated antigen-committed CD8(+) T cells only in the tumor microenvironment. Galectin-3-deficient mice exhibit improved CD8(+) T-cell effector function and increased expression of several inflammatory genes. Galectin-3 binds to LAG-3, and LAG-3 expression is necessary for galectin-3-mediated suppression of CD8(+) T cells in vitro. Lastly, galectin-3-deficient mice have elevated levels of circulating plasmacytoid dendritic cells, which are superior to conventional dendritic cells in activating CD8(+) T cells. Thus, inhibiting galectin-3 in conjunction with CD8(+) T-cell-directed immunotherapies should enhance the tumor-specific immune response.

Inoculation site from a cutaneous melanoma patient treated with an allogeneic therapeutic vaccine: a case report.

We have developed a therapeutic vaccine consisting of a mixture of lethally-irradiated allogeneic cutaneous melanoma cell lines with BCG and GM-CSF as adjuvants. The CSF-470 vaccine is currently being assayed in a Phase II–III trial against medium-dose IFN-α2b. All vaccinated patients immunized intradermally developed large edematous erythema reactions, which then transformed into subcutaneous nodules active for several months. However, vaccine injection sites were not routinely biopsied. We describe the case of a female patient, previously classified as stage III, but who, due to the simultaneous discovery of bone metastases only received one vaccination was withdrawn from the study, and continued her treatment elsewhere. This patient developed a post-vaccination nodule which was surgically removed 7 weeks later, and allowed to analyze the reactivity and immune profiling of the inoculation site. An inflammatory reaction with zones of fibrosis, high irrigation, and brisk lymphoid infiltration, primarily composed of CD8+ and CD20+ lymphocytes, was observed. There were no remaining BCG bacilli, and scarce CD4+ and Foxp3+ T cells were determined. MART-1 Ag was found throughout the vaccination site. CD11c+ Ag presenting cells were either dispersed or forming dense nests. Some CD11c+ cells proliferated; most of them contained intracellular MART-1 Ag, and some interacted with CD8+ lymphocytes. These observations suggest a potent, long-lasting local inflammatory response with recruitment of Ag-presenting cells that incorporate melanoma Ags, probably leading to Ag presentation to naïve T cells.

Phase II, randomized study of GVAX pancreas and CRS-207 immunotherapy in patients with metastatic pancreatic cancer: Clinical update on long term survival and biomarker correlates to overall survival.

261 Background: In a phase 2a randomized study, metastatic pancreatic ductal adenocarcinoma (PDA) patients treated sequentially with two vaccine-based immunotherapies showed extended overall survival (OS) with tolerable side effects. Treatment included low-dose cyclophosphamide (CY) to inhibit T-regulatory cells prior to GVAX, an irradiated GM-CSF-secreting allogeneic PDA cell vaccine, which activates a broad antigenic response, followed by CRS-207, a live-attenuated, mesothelin-expressing Listeria monocytogenes vaccine which stimulates innate and adaptive immunity. Methods: Patients were enrolled with metastatic PDA who received or refused ≥1 prior chemotherapy, had ECOG ≤1 and adequate organ function. Patients were randomized 2:1 to receive 2 doses of CY/GVAX followed by 4 doses of CRS-207 (Arm A) or 6 doses of CY/GVAX (Arm B). PBMC and serum were collected over the course of treatment for immune and biomarker analyses. CyTOF, ELISPOT, and luminex were used to identify biomarker correlates of OS. Results: We previously reported phase 2a results demonstrating median OS in patients treated in arm A was 6.1 months compared to 3.9 months for those in arm B (HR=0.54, one-sided p=0.011). As of August 2014, 8 patients are still alive (median time on study: 768 days; range: 596-880), with 3 subjects on combination treatment. Mesothelin-specific CD8+T cell responses following CY/GVAX correlated with improved OS in both arms. Elevated frequencies of T cell subsets and a panel of baseline serum cytokines also correlated with longer OS. Strikingly, hierarchical clustering based on expression of biomarkers showed significant clustering of patients according to OS. Conclusions: Treatment with CY/GVAX and CRS-207 was well-tolerated and resulted in improved OS compared to CY/GVAX alone. A larger phase 2b, 3-arm, randomized trial is ongoing and plans to treat 240 adults with previously-treated metastatic PDA with CY/GVAX and CRS-207, CRS-207 alone, or standard chemotherapy. Preliminary results using patients’ PBMCs and sera revealed potential biomarkers for OS. Clinical trial information: NCT01417000. Clinical trial information: NCT01417000.

Preliminary analysis of immune responses in patients enrolled in a Phase II trial of cyclophosphamide with allogenic dribble vaccine alone (DPV-001) or with GM-CSF or imiquimod for adjuvant treatment of stage IIIa or IIIb NSCLC

Meeting abstracts Tumor-derived autophagosomes, DRibbles, are DC-targeted microvesicles containing more than 100 putative NSCLC antigens, many as potential altered-peptide ligands (APL), which could increase their immunogenicity. The microvesicles also contain at least 15 DAMPs with agonist

Long-term survival in unfavorable-risk mRCC patients after intratumoral administration of a cell-based allogeneic vaccine adjuvant.

e14006 Background: Initial data from a Phase I/II study in patients with recently diagnosed metastatic RCC demonstrated that intratumoral administration of a cell based allogeneic vaccine adjuvant ...

Locally secreted Fc-OX40L is superior to systemic, antibody mediated, OX40 costimulation for combination immunotherapy

The dramatic clinical success of checkpoint inhibitory therapy (anti-CTLA-4 and anti-PD-1) in a small percentage of patients has highlighted the need to identify combination approaches that may increase the frequency of responders. Two immunotherapy modalities that are proposed to synergize both with each other, and with checkpoint inhibitors are therapeutic vaccines and T cell co-stimulators. To prioritize which T cell co-stimulators enhance the efficacy of an allogeneic, gp96-Ig secreting, cell-based vaccine, we investigated the activity of agonistic antibodies targeting OX40, 4-1BB and ICOS administered together with gp96-Ig vaccines (ImPACT). These data demonstrated that antigen-specific CD8+ T cell expansion is significantly enhanced by OX40, but not 4-1BB or ICOS stimulation. Because T cell co-stimulation occurs at the site of immunization, we then asked when co-expression of Fc-OX40L by the gp96-Ig secreting allogeneic vaccine cells (ComPACT) would provide comparable co-stimulation to systemically administered OX40 agonist antibodies (Figure A). Interestingly, these data demonstrated that locally secreted Fc-OX40L provided superior priming of antigen-specific CD8+ T cells (peak of 14.05% of total CD8+) as compared to combinations with OX40 antibodies (8.9%) or vaccine alone (5.2%) (Figure B). The reason for the beneficial response was related to more potent activation of CD127+KLRG-1- memory precursor cells by the Fc-OX40L expressing vaccine. Importantly, antigen-specific CD8+ cells stimulated by vector-encoded Fc-OX40L demonstrated a protracted contraction phase after priming, and remained at high levels in both tissues and peripheral blood for 3 weeks after priming (Figure C). Systemic administration of OX40 antibodies also led to proliferation of antigen non-specific CD4+ T cells, Treg and systemic increases in IL-4, IL-5, IL-6, TNFα and IFNα. Importantly, vaccine-expressed Fc-OX40L led to high frequencies of IFNα+, TNFα+, granzyme-b+ and IL-2+ antigen-specific CD8+ T cells at both priming and boosting, which enhanced rejection of established CT26 tumors. These data demonstrate that vaccination and co-stimulation can be approached with a single cell-based product, and that locally delivery of a vaccine and T cell co-stimulator enhances the primary and memory responses of highly activated CD8+ T cells as compared to co-stimulatory antibodies. This may lead to more rapid development of combination immunotherapeutics with reduced toxicity, as a result of increased specificity, and a simpler cost structure than combining multiple independent biologic medicines. Figure 1

Safety and tolerability of allogeneic dendritic cell vaccination with induction of Wilms tumor 1–specific T cells in a pediatric donor and pediatric patient with relapsed leukemia: a case report and review of the literature

A 15-year-old girl with acute lymphoblastic leukemia received allogeneic dendritic cell vaccination, pulsed with Wilms tumor 1 (WT1) peptide, after her third hematopoietic stem cell transplantation (HSCT). The vaccines were generated from the third HSCT donor, who was her younger sister, age 12 years. The patient received 14 vaccines and had no graft-versus-host disease or systemic adverse effect, aside from grade 2 skin reaction at the injection site. WT1-specific immune responses were detected after vaccination by both WT1-tetramer analysis and enzyme-linked immunosorbent spot assay. This strategy may be safe, tolerable and even feasible for patients with a relapse after HSCT.

Preliminary analysis of immune responses in patients enrolled in a Phase II trial of Cyclophosphamide with Allogenic DRibble Vaccine Alone (DPV-001) or with GM-CSF or Imiquimod for adjuvant treatment of Stage IIIA or IIIB NSCLC

Meeting abstracts Tumor-derived autophagosomes, DRibbles, are novel cancer vaccines that have been shown to be effective in preclinical models of established tumors. We hypothesize that DRibbles' efficacy stems from their ability to present stabilized tumor-derived short-lived proteins (SLiPs) and

Abstract 2811: Allogeneic cell cased vaccine development by shared antigen screening

Abstract The fundamental premise of allogeneic vaccines for cancer relies upon the presence of common antigens that are shared between established cell lines and a large proportion of patients with histologically related tumors. Recent results from The Cancer Genome Atlas have clearly demonstrated that somatic mutations in exon region DNA, while potentially immunogenic, do not result in the translation of antigenic proteins that are similar from patient to patient. Instead, these data reinforce the concept that dysregulation of common pathways contributes to the general property of de-differentiation in tumor cells and the acquisition of immature phenotypes as compared to untransformed precursor cells. This phenomenon leads to expression of mucinous and embryonal antigens, collectively known as cancer testis antigens, that are otherwise rare in mature tissues and to which central tolerance remains incomplete. We have developed allogeneic vaccines based on parallel screening of non-small cell lung, bladder, triple-negative breast, ovarian and melanoma tumor cell lines and patient tumor samples. The baseline expression of certain antigens, including SSX2, SSX4, CT10, MAGE-A1, MAGE-A10, LAGE-1 and NY-ESO-1 was found to vary widely both between tumor samples and non-transformed tissue controls. Among all antigens screened, MAGE-A3 was most commonly upregulated across transformed tissue samples, however other antigens including BAGE-1, XAGE-1b and MAGE-A10 were found to be most dramatically upregulated. This analysis provides a screening tool with which to appropriately profile and prioritize individual cell lines for vaccine development in histologically diverse tumor types. Citation Format: Vadim V. Deyev, Neal Schilling, Taylor H. Schreiber. Allogeneic cell cased vaccine development by shared antigen screening. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2811. doi:10.1158/1538-7445.AM2014-2811

Gene expression profiling of peripheral blood mononuclear cells during treatment with a gene-modified allogeneic tumor cell vaccine in advanced renal cell cancer: tumor-induced immunosuppression and a possible role for NF-κB.

Tumor-induced immunosuppression remains a major challenge for immunotherapy of cancer patients. To further elucidate why an allogeneic gene-modified [interleukin-7 (IL-7)/CD80-cotransfected] renal cell cancer (RCC) vaccine failed to induce clinically relevant TH-1-polarized immune responses, peripheral blood mononuclear cells from enrolled study patients were analyzed by gene expression profiling (GEP) both prior and after vaccination. At baseline before vaccination, a profound downregulation of gene signatures associated with antigen presentation, immune response/T cells, cytokines/chemokines and signaling/transcription factors was observed in RCC patients as compared to healthy controls. Vaccination led to a partial reversion of preexisting immunosuppression, however, GEP indicated that an appropriate TH-1 polarization could not be achieved. Most interestingly, our results suggest that the nuclear factor-kappa B signaling pathway might be involved in the impairment of immunological responsiveness and the observed TH-2 deviation. In summary, our data suggest that GEP might be a powerful tool for the prediction of immunosuppression and the monitoring of immune responses within immunotherapy trials.

Abstract SY26-01: Vaccine induced immunity against cancer genes to prevent and treat pancreatic cancer

Abstract Pancreatic cancer remains a “death sentence,” with the poorest survival rates reported for solid tumors. Escalating this problem is the fact that pancreatic cancer is among the most resistant cancers to traditional forms of therapy. But in this new era of targeted therapies, there is reason to hope that significant progress will be made in the development of new interventions for both treatment and prevention in the near future. In fact, we have entered into a new era of cancer therapies and are witnessing the rapid approval of antibodies and small molecule agents that inhibit cancer associated pathways. In the past few years we have also witnessed the approval of vaccines for cancer prevention (HPV vaccines, Gardasil, Cervarix) and cancer treatment (prostate cancer vaccine, Sipuleucel-T, Provenge); and the first immune modulating agent (Yervoy, Ipilimumab) that blocks the down regulatory signal, CTLA-4 on T cells, thereby enhancing immune activity against malignant melanoma. These groundbreaking examples have opened the floodgates for a whole new class of anticancer agents that harness the power of the immune system. Until recently, barriers to immunotherapy clinical successes for pancreatic cancer have been due to a lack of understanding of the immune pathways within the pancreatic tumor microenvironment that hinder successful immune responses even at the earliest stages of cancer development. Recent advances in our understanding of its immunobiology has identified new targets for developing cancer specific vaccines and new targets for modulating the tumor microenvironment to allow more potent activation and improved access of vaccine induced immune responses. We are just learning that non-neoplastic cells, including cancer-associated myofibroblasts, regulatory T cells, dendritic cells, myeloid-derived suppressor cells, and tumor-associated macrophages, are hijacked by pre-invasive and invasive cancer cells to create a tolerogenic tumor microenvironment. Current research is focused on elucidating the mechanisms of this cancer supporting polarization within the tumor microenvironment with the goal of tipping the balance in favor of an anticancer immunity. With the recent advances in molecular technologies and the development of relevant pancreatic cancer mouse models, it is now within our reach to dissect the inhibitory pathways within the pancreatic tumor microenvironment. This will in turn, lead to new therapeutic opportunities that will eliminate these barriers and convert this deadly cancer into a treatable and hopefully preventable disease. This presentation will provide new data supporting a role for targeting tumor initiating and metastasis supporting genes as immunotherapy for preventing tumor initiation and progression.

Immunotherapeutic Agents in Non-small-cell Lung Cancer Finally Coming to the Front Lines

Non-small-cell lung cancer usually carries a dismal prognosis. Novel treatment approaches are clearly warranted. Immunotherapy has emerged as a promising area of research developing agents that manipulate the immune system to induce antitumor responses while avoiding major toxicity. New vaccines and checkpoint inhibitors are currently undergoing investigation in phase II and phase III clinical trials. In advanced non-small-cell lung cancer (NSCLC), belagenpumatucel-L, an allogeneic cell vaccine directed against transforming growth factor β in the tumor microenvironment, knocks down the immune suppression caused by the tumor and has demonstrated a dose- and time-dependent efficacy in some subgroups of patients. L-BLP25 and TG4010 are both antigenic vaccines that target mucin 1, whose encoding proto-oncogene is commonly mutated in solid tumors. The L-BLP25 vaccine achieved a significant improvement in overall survival in the subgroup of patients with stage IIIB NSCLC treated with chemoradiotherapy. TG4010 vaccination resulted in better progression-free survival when added to cisplatin-gemcitabine chemotherapy. These results are being addressed in the currently ongoing phase III TIME trial. In the adjuvant setting, MAGE-A3, an antigen-based vaccine, showed promising results in melanoma-associated antigen A3 positive lung cancer patients who underwent resection in the phase II study; however, no improvement in progression-free survival was observed in the phase III MAGRIT study. CIMAVax is a recombinant human epidermal growth factor (EGF) vaccine that induces anti-EGF antibody production and prevents EGF from binding to its receptor. It has improved overall survival in patients with advanced NSCLC who achieve seroconversion. Ipilimumab, an immune checkpoint inhibitor that targets cytotoxic T-lymphocyte antigen 4, demonstrated improved progression-free survival in advanced NSCLC patients who received the drug after chemotherapy in a phased regimen. Finally, anti-programmed death receptor 1 agents have achieved durable response rates in phase I studies. This review gives an overview of the current data and the most promissory immunotherapeutic agents for NSCLC.

Novel pancreatic cancer vaccines could unleash the army within.

Despite recent progress with novel chemotherapy regimens, pancreatic ductal adenocarcinoma remains the fourth leading cause of cancer death in the United States. Innovative approaches to treatment of this disease are needed to accelerate progress. A review was conducted of the results of 2 pancreatic cancer vaccine programs with results that have shown promise in early-phase clinical trials. In a phase 2 trial, a cell-based allogeneic pancreatic cancer vaccine exploiting the hyperacute rejection response targeted against alpha-1,3 galactosyl epitopes (algenpantucel-L) has shown improvement in disease-free and overall survival rates in the adjuvant setting compared with a historical control. This vaccine has advanced to ongoing phase 3 trials. Compared with GVAX alone, a second whole-cell vaccine employing GM-CSF-expressing pancreatic cancer cells (GVAX) to enhance the antigen presentation in a priming phase followed by a Listeria-based vaccine targeting mesothelin in a boost phase improved survival rates. This vaccine platform is undergoing additional phase 2 testing. Allogenic whole-cell pancreatic adenocarcinoma vaccines show promise in early-phase trials and have the potential to improve survival rates by unleashing antitumor immunity.

Immunotherapy converts nonimmunogenic pancreatic tumors into immunogenic foci of immune regulation.

Pancreatic ductal adenocarcinoma (PDAC) is considered a "nonimmunogenic" neoplasm. Single-agent immunotherapies have failed to demonstrate significant clinical activity in PDAC and other "nonimmunogenic" tumors, in part due to a complex tumor microenvironment (TME) that provides a formidable barrier to immune infiltration and function. We designed a neoadjuvant and adjuvant clinical trial comparing an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting, allogeneic PDAC vaccine (GVAX) given as a single agent or in combination with low-dose cyclophosphamide to deplete regulatory T cells (Treg) as a means to study how the TME is altered by immunotherapy. Examination of resected PDACs revealed the formation of vaccine-induced intratumoral tertiary lymphoid aggregates in 33 of 39 patients 2 weeks after vaccine treatment. Immunohistochemical analysis showed these aggregates to be regulatory structures of adaptive immunity. Microarray analysis of microdissected aggregates identified gene-expression signatures in five signaling pathways involved in regulating immune-cell activation and trafficking that were associated with improved postvaccination responses. A suppressed Treg pathway and an enhanced Th17 pathway within these aggregates were associated with improved survival, enhanced postvaccination mesothelin-specific T-cell responses, and increased intratumoral Teff:Treg ratios. This study provides the first example of immune-based therapy converting a "nonimmunogenic" neoplasm into an "immunogenic" neoplasm by inducing infiltration of T cells and development of tertiary lymphoid structures in the TME. Post-GVAX T-cell infiltration and aggregate formation resulted in the upregulation of immunosuppressive regulatory mechanisms, including the PD-1-PD-L1 pathway, suggesting that patients with vaccine-primed PDAC may be better candidates than vaccine-naïve patients for immune checkpoint and other immunomodulatory therapies.