Live-attenuated Listeria Monocytogenes Research Articles

A phase I study of ADXS-504, a cancer type specific immunotherapy, for patients with biochemically recurrent prostate cancer.

TPS5115 Background: Roughly 20%-30% of prostate cancer patients experience biochemical recurrence (BCR), rising prostate-specific antigen (PSA) levels, after definitive therapy with radical prostatectomy (RP) or radiation therapy (RT). The optimal therapy and timing of treatment for BCR is unknown, however, for patients who are not eligible for salvage radiation, androgen deprivation therapy (ADT) is the standard first-line treatment. ADT is an effective therapy but has many acute and long-term toxicities. Novel strategies to reduce ADT exposure and prolong disease control are needed. ADXS-504 is a live attenuated Listeria monocytogenes (Lm)-based immunotherapy consisting of a truncated nonhemolytic fragment of listeriolysin O (tLLO) fused to a total of 24 tumor associated antigens (TAA). ADXS-504 was designed so that nearly 20% of patients with BCR cancer will express at least one of the targeted hotspot mutation peptide antigens and that >90% will express at least one of the TAAs targeted by the sequence-optimized TAA peptide antigens. By combining these shared, commonly expressed antigen targets into a single Lm-based immunotherapy, ADXS-504 provides the potential for a potent, disease-specific approach to treating patients with prostate cancer. In addition to the generation of antigen-specific T cell responses, treatment with Lm-based immunotherapies has been shown to reprogram the tumor microenvironment (TME), by reducing the frequencies and function of immunosuppressive regulatory T cells and myeloid-derived suppressor cells within the TME. A pre-clinical murine model showed that a proto-type Lm-construct could reduce the number of metastases after removal of the primary tumor by eliminating residual tumor cells. We hypothesize that ADXS-504 is safe and promotes anti-tumor immune responses that may delay or prevent the use of ADT in castration sensitive prostate cancer. Methods: This is an open-label dose-escalation phase I trial of ADXS-504 in patients with BCR of prostate cancer previously treated with RP or RT. The study will enroll up to 18 subjects with BCR with a PSA ≥ 0.3 and a PSADT ≥ 4 months without evidence of metastatic disease on traditional CT imaging and bone scans. ADXS-504 will be given by IV every 4 weeks level for 6 study treatments, followed by maintenance therapy given every 12 weeks for 4 doses for overall total of 10 doses of study treatment. DLTs will be evaluated over the first 28 days of treatment. PSA response, PSADT, and adverse events will be summarized. The Kaplan- Meier method will be used to estimate time to PSA progression and rPFS. Immunologic activity will be evaluated by ELISpot analysis, flow cytometry, and multiplex assays and blood samples will be collected for gene sequencing analysis. The study is currently open to enrollment. Clinical trial information: NCT05077098.

Safety and efficacy of prophylactic and therapeutic vaccine based on live-attenuated Listeria monocytogenes in hepatobiliary cancers

Primary liver cancer (PLC) comprising hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) represents the third deadliest cancer worldwide with still insufficient treatment options. We have previously found that CD4 T helper 1 (Th1) response is indispensable for the protection against PLC. In the present research, we aimed to test the potent inducers of Th1 responses, live-attenuated Listeria monocytogenes ∆actA/∆inlB strain as preventive/therapeutic vaccine candidate in liver fibrosis, HCC, and CCA. Studies were performed using autochthonous models of HCC and CCA, highly reflecting human disease. L. monocytogenes ∆actA/∆inlB demonstrated strong safety/efficacy in premalignant and malignant liver diseases. The protective mechanism relied on the induction of strong tumor-specific immune responses that keep the development of hepatobiliary cancers under control. Combination therapy, comprising Listeria vaccination and a checkpoint inhibitor blockade significantly extended the survival of HCC-bearing mice even at the advanced stages of the disease. This is the first report on the safety and efficacy of Listeria-based vaccine in liver fibrosis, as well as the first proof of principle study on Listeria-based vaccines in CCA. Our study paves the way for the use of live-attenuated Listeria as safe and efficient vaccine and a potent inducer of protective immune responses in liver fibrosis and hepatobiliary malignancies.

Highlights of This Issue

ErbB3 activation leads to resistance to EGFR inhibition in cancer, and the ErbB3 ligand neuregulin-1 (NRG1) is expressed in most head and neck squamous cell carcinomas (HNSCC). Duvvuri and colleagues conducted a window-of-opportunity trial in HNSCC patients to characterize the biologic activity of CDX-3379, a human anti-ErbB3 monoclonal antibody. CDX-3379 modulated pErbB3 in tumors and led to a marked clinical response in a subset of patients. These data provide the rationale for further development of CDX-3379 in HNSCC and additional ErbB3-/NRG-expressing tumor types.Malignant pleural mesothelioma (MPM) is a rare but lethal cancer. In a Phase Ib trial, Hassan and colleagues assessed the combination of pemetrexed and cisplatin with CRS-207, a live-attenuated Listeria monocytogenes vaccine expressing the mesothelin antigen in mesothelioma. This combination altered the tumor microenvironment to increase anti-tumor immune cells. Moreover, objective tumor responses were observed in most patients, with 89% demonstrating either complete response, partial response, or stable disease. These results support further clinical examination of the combination of chemotherapy and immune therapy in mesothelioma.Naturally occurring canine lung cancer shares many features with human disease, particularly in never-smokers. The molecular mechanisms of canine lung carcinogenesis, however, have not been assessed. Lorch and colleagues assessed the genomic landscape of canine lung cancer and found recurrent HER2 mutations in canine pulmonary adenocarcinoma, but not in adenosquamous or squamous cell carcinomas. The majority of the HER2 mutations observed were the V659E hotspot mutation that commonly occurs in human disease. These results further confirm naturally occurring canine lung adenocarcinoma as a comparable model to human lung cancers in never-smokers.4-1BB is a key costimulatory immunoreceptor which enhances cytolytic activity of T and NK cells when activated. Attempts to agonize the pathway via conventional antibodies, however, have been hampered by peripheral toxicity. To facilitate tumor-localized T-cell costimulation, Hinner and colleagues synthesized PRS-343, a 4-1BB/HER2 bispecific molecule. PRS-343 led to effective 4-1BB-mediated costimulation of T cells in vitro in the presence of HER2-positive cancer cells. In a humanized mouse model, PRS-343 treatment led to tumor growth inhibition and a dose-dependent increase of tumor-infiltrating lymphocytes. These data support the clinical trials now underway assessing the efficacy and safety of PRS-343.

A Potent and Effective SuicidalListeriaVaccine Platform

Live-attenuated Listeria monocytogenes has shown encouraging potential as an immunotherapy platform in preclinical and clinical settings. However, additional safety measures will enable application across malignant and infectious diseases. Here, we describe a new vaccine platform, termed Lm-RIID (L. monocytogenes recombinase-induced intracellular death), that induces the deletion of genes required for bacterial viability yet maintains potent T cell responses to encoded antigens. Lm-RIID grows normally in broth but commits suicide inside host cells by inducing Cre recombinase and deleting essential genes flanked by loxP sites, resulting in a self-limiting infection even in immunocompromised mice. Lm-RIID vaccination of mice induces potent CD8+ T cells and protects against virulent challenges, similar to live L. monocytogenes vaccines. When combined with α-PD-1, Lm-RIID is as effective as live-attenuated L. monocytogenes in a therapeutic tumor model. This impressive efficacy, together with the increased clearance rate, makes Lm-RIID ideal for prophylactic immunization against diseases that require T cells for protection.

Abstract B15: Combination immunotherapy of murine prostate cancer using a Listeria-based PSA vaccine: Immune correlates of efficacy and resistance development

Abstract Combining immunotherapy and radiation has emerged as a promising strategy to boost efficacy of diverse immunotherapeutic agents including tumor vaccines. Immuno-radiotherapy uses radiation to increase antigen exposure and, potentially, to amplify and broaden immune responses triggered by tumor vaccines or checkpoint inhibitors. Here we explored the therapeutic potential of combining radiation therapy (RT) and a prostate cancer vaccine (ADXS-PSA) currently in clinical development. ADXS-PSA is a live-attenuated Listeria monocytogenes (Lm)-based vector expressing human PSA (Haas et al., J Immunother Cancer 2015:3(Suppl.2):P153). We confirm and extend earlier observations (Hannan et al., Can Immunol Immunother 61:2227) that the two treatment modalities cooperatively induce regression of syngeneic prostate cancer cells expressing human PSA (TPSA23). The extent of tumor growth inhibition depended on temporal sequencing of vaccine and RT with concurrent administration being superior to other treatment schedules. Using the optimal sequencing protocol, tumors were collected during (day 20) and after treatment (day 38) post-implantation to assess immune infiltrates and function during initial tumor regression and upon resumption of tumor growth. Tumor regression by the RT/vaccine combination was associated with enhanced T cell activation and robust IFNγ signatures in the tumor microenvironment as determined by transcriptome analyses. TCRβ chain sequencing revealed elevated and sustained T cell diversity in tumor tissue of mice receiving the RT/vaccine combination. Transcriptome analysis further revealed that sustained T cell diversity in the RT/vaccine group was accompanied by higher expression levels of resident and/or memory phenotypic markers. Finally, molecular analysis of recurring tumors revealed induction of select immune checkpoints (including PD-L1 and CD137) as a function of treatment, establishing a rationale to test whether therapeutic efficacy can be boosted further by targeting these markers. The results obtained support combining ADXS-PSA with radiation in the clinic and provide a versatile experimental platform to optimize combination immunotherapeutic strategies. Citation Format: Emily K. Bongiorno, Trevor Baybutt, Carla Portocarrero, Adam Snook, Adam P. Dicker, Sandra M. Hayes, Ulrich Rodeck. Combination immunotherapy of murine prostate cancer using a Listeria-based PSA vaccine: Immune correlates of efficacy and resistance development [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr B15.

Tolerability of ADXS11-001 Lm-LLO Listeria-Based Immunotherapy With Mitomycin, Fluorouracil, and Radiation for Anal Cancer

Toobtain safety and preliminary efficacy data of the combination of ADXS11-001, live attenuated Listeria monocytogenes bacterium, with mitomycin, 5-fluorouracil (5-FU), and intensity modulated radiation therapy in locally advanced anal cancer. Eligibility included patients with previously untreated, nonmetastatic anal cancer with a primary tumor >4cm or node-positive disease. Patients received 2 cycles of mitomycin and 5-FU concurrent with 54.0Gy intensity modulated radiation therapy. One intravenous dose of ADXS11-001 (1×109colony-forming units) was administered before chemoradiation; 3 additional monthly doses were given after chemoradiation. Ten patients were treated, including 1 with N2 and 4 with N3 disease. Two patients had grade 3 acute toxicities after the initial dose of ADXS11-001, including chills/rigors (n=2), back pain (n=1), and hyponatremia (n=1). All ADXS11-001 toxicities occurred within 24hours of administration. There was no apparent increase in chemoradiation toxicities or myelosuppression. One patient had a grade 5 cardiopulmonary event shortly after beginning 5-FU treatment. All 9 assessable patients had complete clinical responses by sigmoidoscopy. Eight of 9 patients (89%) are progression-free at a median follow-up of 42months. Preliminary data show that ADXS11-001 can be safely administered with standard chemoradiation for anal cancer. Further studies of listeria-based immunotherapy with radiation are warranted.

ADXS11-001 Lm-LLO Immunotherapy, Mitomycin, 5-fluorouracil (5-FU) and Intensity-modulated radiation therapy (IMRT) for Anal Cancer.

e15072 Background: Human papillomavirus (HPV) DNA is present in the majority of anal cancer. ADXS11-001 Lm-LLO immunotherapy is a live attenuated Listeria monocytogenes ( Lm) bioengineered to secrete a HPV-16-E7 fusion protein targeting HPV transformed cells. The Lmvector is phagocytosed by antigen presenting cells where it cross presents, stimulating MHC class 1 and 2 pathways resulting in specific T-cell immunity. The objective of this study was to determine the safety of ADXS11-001 with mitomycin, 5-FU and IMRT (chemoradiation therapy, CRT) and obtain preliminary data on progression free survival (PFS) in locally advanced anal cancer. Methods: Eligibility included patients (pts) with anal squamous cell cancer and stages T1N2-N3; T2( < 4 cm)N1-N3; T2(≥4cm)N0-N3, T3N0-3, T4N0-3; without evidence of metastases. Pts received standard 54 Gy IMRT with 2 cycles of mitomycin and 5-FU. ADXS11-001, 1x109colony forming units IV, was given x 1 dose before CRT then x 3 additional monthly doses after CRT. Results: The study enrolled the first pt in April 2013. Ten patients were treated (median age 62.5, range 37-71) including 5 with pelvic adenopathy. Two patients had grade 3 toxicities related to the vaccine including chills/rigors (n = 2), back pain (n = 1), hyponatremia (n = 1). All toxicities were within 24 hours of the vaccine and resolved successfully with standard care. There was no exacerbation of CRT toxicities or myelosuppression. One patient had a grade 5 cardiopulmonary event shortly after beginning 5-FU treatment which was judged to be unlikely related to ADXS11-001and possibly related to CRT. Eight patients treated on the study had a complete response at six-month sigmoidoscopy. One additional patient who did not undergo six-month sigmoidoscopy had complete response on sigmoidoscopy performed at approximately one year. Eight of 9 patients (89%) are disease-free at a median follow-up of 34 months. Conclusions: ADXS11-001 can be safely administered with CRT for anal cancer. Promising PFS was observed in patients with locally advanced disease. Clinical trial information: NCT01671488.

Mesothelin Immunotherapy for Cancer: Ready for Prime Time?

Mesothelin is a tumor antigen that is highly expressed in many human cancers, including malignant mesothelioma and pancreatic, ovarian, and lung adenocarcinomas. It is an attractive target for cancer immunotherapy because its normal expression is limited to mesothelial cells, which are dispensable. Several antibody-based therapeutic agents as well as vaccine and T-cell therapies directed at mesothelin are undergoing clinical evaluation. These include antimesothelin immunotoxins (SS1P, RG7787/LMB-100), chimeric antimesothelin antibody (amatuximab), mesothelin-directed antibody drug conjugates (anetumab ravtansine, DMOT4039A, BMS-986148), live attenuated Listeria monocytogenes-expressing mesothelin (CRS-207, JNJ-64041757), and chimeric antigen receptor T-cell therapies. Two antimesothelin agents are currently in multicenter clinical registration trials for malignant mesothelioma: amatuximab in the first-line setting and anetumab ravtansine as second-line therapy. Phase II randomized clinical trials of CRS-207 as a boosting agent and in combination with immune checkpoint inhibition for pancreatic cancer are nearing completion. These ongoing studies will define the utility of mesothelin immunotherapy for treating cancer.

Abstract LB-095: HPV E7 antigen-expressing Listeria-based immunotherapy (ADXS11-001) prior to robotic surgery for HPV-positive oropharyngeal cancer enhances HPV-specific T cell immunity

Abstract Human papilloma virus-associated oropharyngeal cancer (HPVOPC), which accounts for almost 75% of newly diagnosed OPC, is an appealing target for immunotherapy due to the expression of viral antigens. ADXS11-001, a live attenuated Listeria monocytogenes listeriolysin O (LLO) immunotherapeutic agent expressing an HPV16-E7 fusion protein, has been shown to induce HPV-specific T cell responses in animal models, and to have clinical activity in cervical cancer. A phase II “window of opportunity” trial was designed to evaluate the effect of ADXS11-001 on anti-tumor immunity in peripheral blood and the tumor immune microenvironment (TIME) of patients with HPVOPC. Previously untreated, surgically resectable, stage II-IV, HPVOPC patients received two doses of ADXS11-001 over 5 weeks prior to transoral robotic surgery. Formalin-fixed paraffin embedded (FFPE) pre-treatment biopsies and post-treatment surgical resection specimens were banked for studies of the TIME. Peripheral blood samples were collected at multiple time points before, during and after ADXS11-001 administration and after surgery. The TIME was profiled by quantitative multiplex immunofluorescence (qIF) microscopy and conventional H&E histopathology. T cell immune responses in the peripheral blood were monitored by ELISPOT of IFN-γ and TNF-α expressing T cells. Serum expression of 38 cytokines was measured using the Luminex multiplex analysis platform. So far 8 patients have completed treatment, of which 5 showed increased E6 or E7-specific IFN-γ responses on the day of surgery or 5 weeks post-surgery, compared to pre-treatment responses. Serum cytokines CCL22 and CXCL10 showed a trend towards increase after ADXS11-001 delivery (p = 0.067, p = 0.070) and drop following surgery (p = 0.069, p = 0.016). CCL22 levels were correlated with E6-specific T cell response after immunotherapy treatment (R2 = 0.6303, p = 0.019). qIF results demonstrated increased post-treatment CD8 and CD4 intratumoral T cell infiltration in 4/8 patients, and correlations between intra-tumoral pre- and post-treatment CD8 numbers (R2 = 0.6481, p = 0.0167). Also, post-treatment PD-1 expression strongly correlated with PD-L1 expression (R2 = 0.8803, p = 0.0007) in the tumor. Tumor infiltrating lymphocytes at the tumor host interface tended to increase after treatment (p = 0.188) and correlated with pre-treatment numbers (R2 = 0.772, p = 0.042). Antigen-specific peripheral blood T cell responses are increased post-treatment with ADXS11-001 and correlate with increased serum CCL22 levels. In this small patient sample (n = 8), the intratumoral qIF and H&E results present an overall suggestion of positive treatment-induced effects in the TIME, which must be confirmed as additional patients are accrued. Citation Format: Rosemarie Krupar, Naoko Imai, Brett Miles, Eric Genden, Krzys Misiukiewicz, Yvonne Saenger, Elizabeth G. Demicco, Jigneshkumar Patel, Phapichaya Chaoprang Herrera, Falguni Parikh, Michael Donovan, Seunghee Kim-Schulze, Marshall Posner, Sacha Gnjatic, Andrew G. Sikora. HPV E7 antigen-expressing Listeria-based immunotherapy (ADXS11-001) prior to robotic surgery for HPV-positive oropharyngeal cancer enhances HPV-specific T cell immunity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-095.

A stable live bacterial vaccine

Formulating vaccines into a dry form enhances its thermal stability. This is critical to prevent administering damaged and ineffective vaccines, and to reduce its final cost. A number of vaccines in the market as well as those being evaluated in the clinical setting are in a dry solid state; yet none of these vaccines have achieved long-term stability at high temperatures. We used spray-drying to formulate a recombinant live attenuated Listeria monocytogenes (Lm; expressing Francisella tularensis immune protective antigen pathogenicity island protein IglC) bacterial vaccine into a thermostable dry powder using various sugars and an amino acid. Lm powder vaccine showed minimal loss in viability when stored for more than a year at ambient room temperature (∼23°C) or for 180days at 40°C. High temperature viability was achieved by maintaining an inert atmosphere in the storage container and removing oxygen free radicals that damage bacterial membranes. Further, in vitro antigenicity was confirmed by infecting a dendritic cell line with cultures derived from spray dried Lm and detection of an intracellularly expressed protective antigen. A combination of stabilizing excipients, a cost effective one-step drying process, and appropriate storage conditions could provide a viable option for producing, storing and transporting heat-sensitive vaccines, especially in regions of the world that require them the most.

Phase II study of ADXS11-001 in patients with persistent/recurrent, locoregional or metastatic squamous cell carcinoma of the anorectal canal.

TPS786 Background: ADXS11-001 is a live attenuated Listeria monocytogenes (Lm)-listeriolysin O (LLO) immunotherapy bioengineered to secrete an antigen-adjuvant fusion protein (fused to HPV16 E7) that has demonstrated promising single-agent activity in human papilloma virus-driven cancers (e.g., head and neck, cervical) and promising clinical activity in combination with chemoradiation in high-risk squamous cell carcinoma (SCC) of the anorectal canal. This study will assess the efficacy and safety of ADXS11-001 monotherapy in patients with persistent/recurrent, locoregional or metastatic anorectal SCC. Methods: Phase 2, multicenter, open-label, 2-stage trial (NCT02399813). Eligible patients (female or male; ≥ 18 years) will have histologically confirmed, measurable (defined by Response Evaluation Criteria In Solid Tumors [RECIST] 1.1) anorectal SCC, previously have received ≥ 1 line of therapy for metastatic/locally advanced disease, Eastern Cooperative Oncology Group performance status of 0 or 1 with adequate organ function. Patients will receive intravenous ADXS11-001 (1×109 colony-forming units) every 3 weeks during a 9-week treatment cycle for ≤ 2 years or until a discontinuation criterion is met (eg documented progression, unacceptable adverse events [AEs], noncompliance with study procedures or treatments). Tumor assessments will occur every 9 weeks. AEs will be monitored throughout the study and will be graded according to the National Cancer Institute-Common Toxicity Criteria version 4.0. The study will be conducted in a 2-stage design. Stage 1 will evaluate the safety and efficacy of ADXS11-001 in 31 patients. If the efficacy from Stage 1 has a response rate (RR) ≥ 10% by RECIST 1.1 or 6-month progression free survival (PFS) ≥ 25%, enrollment will proceed to Stage 2 with the addition of another 24 evaluable patients. RR and PFS will be described for the overall population. The end of the study will be defined as 1 year after the last patient has been enrolled. To date, enrollment has begun at 1 study site. Clinical trial information: NCT02399813.

Randomized phase II study of the safety, efficacy, and immune response of GVAX pancreas (with cyclophosphamide) and CRS-207 with or without nivolumab in patients with previously treated metastatic pancreatic adenocarcinoma (STELLAR).

TPS486 Background: A heterologous prime-boost vaccination strategy using GVAX pancreas and CRS-207 is showing promise in patients with pancreatic adenocarcinoma (PDA) (Le, JCO 2015). Furthermore, blockade of the immune checkpoint programmed death-1 (PD-1) is active in some cancers. Combinatorial strategies aimed at priming tumor antigen-specific T cells while simultaneously blocking negative checkpoints may be necessary to improve outcomes in PDA. GVAX is composed of allogeneic pancreatic cancer cells modified to express GM-CSF and induces a broad response against multiple tumor antigens. GVAX is given with low-dose cyclophosphamide (CY) to inhibit regulatory T cells. CRS-207 is live-attenuated Listeria monocytogenes engineered to express the tumor-associated antigen mesothelin. CRS-207 boosts responses against mesothelin and is unique in its capacity to stimulate both innate and adaptive immunity by activating T cells and NK cells. Nivolumab is an antibody against PD-1. Methods: This is a phase 2 study comparing CY/GVAX and CRS-207 with or without nivolumab in subjects with PDA who failed only one chemotherapy regimen for metastatic disease. Subjects are randomized in a 1:1 ratio to receive either 2 doses of CY/nivolumab/GVAX and 4 doses of nivolumab/CRS-207 (Arm A) or 2 doses of CY/GVAX and 4 doses of CRS-207 (Arm B). The primary objective is to compare OS between Arms A and B. Secondary/exploratory objectives include: assessment of safety and clinical responses (tumor assessments and CA19-9 levels) and correlation of Lm- and mesothelin-specific T cell and other immunological responses with OS, progression-free survival and best overall response. Clinical trial information: NCT02243371.

Clinical and immune characteristics of rapid dropout and long-term survival in a phase II safety and efficacy study of combination CRS-207/GVAX immunotherapy in pancreatic cancer.

459 Background: Baseline patient characteristics may impact duration on study and survivorship of patients in immunotherapy trials. In this study, GVAX pancreas (GM-CSF–secreting allogeneic pancreatic tumor cells) was administered with low-dose cyclophosphamide (Cy), with or without subsequent CRS-207 (live-attenuated Listeria monocytogenes–expressing mesothelin) infusion. Baseline clinical and immunological data were examined for two patient subsets based on duration on study. Methods: Previously treated patients with metastatic pancreatic adenocarcinoma were randomly assigned at a ratio of 2:1 to 2 doses of Cy/GVAX followed by 4 doses of CRS-207 or 6 doses of Cy/GVAX every 3 weeks. Stable patients were offered additional courses. Patients were evaluated for post-randomization duration on study of < 60 days (rapid dropouts, RD) and > 18 months (long-term survivors, LTS). Baseline characteristics of these subsets were examined. Results: A total of 93 patients were randomized. Fifteen patients were RD; 13 were LTS. More RDs versus LTS had liver metastasis and lymph node involvement. On average, fewer RD patients had radiotherapy prior to randomization and fewer had prior surgical intervention. RD averaged 1.73 prior metastatic cancer treatment regimens versus 1.31 in LTS. RD also had higher average baseline CA 19-9 levels. Immune analysis showed higher circulating terminal effector CD8+ T cells and lower serum IL-6 in LTS compared to RD. Serum IL-6 concentration remained lower in LTS at four weeks following initiation of treatment. For patients who received CRS-207, CD8+ T cells specific to listeriolysin O (LLO) and mesothelin were higher in LTS than RD, as determined by ELISPOT. Conclusions: Baseline clinical and immunological characteristics may impact patient duration on immunotherapy trials. Immune monitoring and biomarker analysis in this study is ongoing to identify circulating cellular, tumor biomarkers and genomic (miRNA and mRNA) signatures that may correlate with survival. These findings warrant continued exploration of patient characteristics to identify best candidates for immunotherapy trials. Clinical trial information: NCT01417000.

Radiation therapy and vaccination against tumor-specific EGFRvIII effectively clears tumors in a murine model of head and neck squamous cell carcinoma

EGFRvIII is a constitutively active and tumor-specific deletional mutant of EGFR found in multiple tumor types including glioblastoma multiforme, and has been reported in head and neck squamous cell carcinomas (HNSCC). The deletion of EGFR exons 2-7 results in a novel glycine at the junction and yields a tumor-specific antigen with demonstrated immunogenicity in mice and humans. Using a live-attenuated Listeria monocytogenes- based vaccine expressing a 21-AA neo-peptide from EGFRvIII (LmEGFRvIII), we demonstrated that prophylactic vaccination protects against subsequent challenge with an EGFRvIII-expressing squamous cell carcinoma (SCCVII-EGFRvIII). Similarly, therapeutic vaccination three days post-implantation prevented outgrowth of EGFRvIII-expressing tumors but not parental EGFRvIII-negative tumors. Conversely, we found that LmEGFRvIII vaccination was insufficient to clear large established SCCVII-EGFRvIII tumors despite eliciting large numbers of polyfunctional EGFRvIII-specific CD8+ T cells. We hypothesized that localized inflammation elicited by radiation therapy could recruit EGFRvIII-specific CD8+ T cells into the tumor. We demonstrated that while neither LmEGFRvIII vaccination nor radiation therapy alone were able to control the EGFRvIII-expressing tumors, the combination of LmEGFRvIII and radiation therapy led to tumor regression and durable cures. We are currently exploring the potential mechanisms for their synergy including the role of T cell recruitment, survival and epitope spreading.

Phase I/II study of ADXS11-001 or MEDI4736 immunotherapies alone and in combination, in patients with recurrent/metastatic cervical or human papillomavirus (HPV)-positive head and neck cancer

Meeting abstracts Approaches that target key HPV genes critical for cancer growth and metastasis may improve survival for individuals diagnosed with carcinomas of the uterine cervix or head and neck. ADXS11-001 is a live attenuated Listeria monocytogenes (Lm) -listeriolysin O (LLO) immunotherapy

Phase I study of safety and immunogenicity of ADU-623, a live-attenuated listeria monocytogenes vaccine (ΔactA/ΔinlB) expressing EGFRVIII and NY-ESO-1, in patients with who grade III/IV astrocytomas

Meeting abstracts The neo-antigen EGFRvIII is expressed in multiple tumor types, including high-grade astrocytomas. It is associated with a poor prognosis and resistance to conventional therapies such as chemotherapy and radiation that are part of the standard treatment. We propose that

Mesothelin-targeted immunotherapy CRS-207 in combination with standard of care chemotherapy as treatment for malignant pleural mesothelioma (MPM).

7565 Background: MPM is an aggressive disease with poor prognosis and is relatively refractory to currently available therapies. CRS-207 is live-attenuated Listeria monocytogenes engineered to expr...

A phase IIb, randomized, controlled, multicenter, open-label study of the efficacy and immune response of GVAX pancreas vaccine and CRS-207 compared to chemotherapy or to CRS-207 alone in adults with previously treated metastatic pancreatic adenocarcinoma (ECLIPSE Study).

TPS489 Background: A prime-boost vaccination strategy using GVAX pancreas vaccine and CRS-207 is showing activity in patients with metastatic pancreatic adenocarcinoma (PDA). GVAX is composed of lethally-irradiated, allogeneic pancreatic cancer cells modified to express GM-CSF. GVAX induces a response against multiple tumor antigens and is given after low-dose cyclophosphamide (CY) to inhibit regulatory T cells. CRS-207 is live-attenuated Listeria monocytogenes engineered to express the tumor-associated antigen mesothelin. CRS-207 boosts responses against mesothelin and stimulates both innate and adaptive immunity by activating T cells and NK cells. Results from a phase 2 study demonstrated CY/GVAX plus CRS-207 improved overall survival (OS) compared to CY/GVAX alone (p-value<0.05; Le, GI ASCO 2014). Methods: This is a phase 2b study comparing CY/GVAX and CRS-207 to chemotherapy or to CRS-207 alone in patients with previously-treated metastatic PDA. Patients will be enrolled in two cohorts: 150 patients into a primary cohort of patients with at least two prior chemotherapy regimens for metastatic disease (third + line) and 90 patients into an exploratory cohort of patients with only one prior chemotherapy regimen for metastatic disease (second line). Patients will be randomized in a 1:1:1 ratio to receive 2 doses of CY/GVAX and 4 doses of CRS-207 (Arm A), six doses of CRS-207 (Arm B) or physician’s choice of single-agent chemotherapy (Arm C). The primary objective is to compare OS between Arms A and C in the primary cohort. Secondary/exploratory objectives include: comparison of OS in both primary and exploratory cohorts between all treatment arms, assessment of safety and clinical responses (tumor assessments and CA19-9 levels) and correlation of Lm- and mesothelin-specific T cell and other immunological responses with clinical responses. Updated enrollment will be reported. (Sponsor: Aduro BioTech, Inc.; NCT02004262). Clinical trial information: NCT02004262.

Safety and Survival With GVAX Pancreas Prime and Listeria Monocytogenes–Expressing Mesothelin (CRS-207) Boost Vaccines for Metastatic Pancreatic Cancer

GVAX pancreas, granulocyte-macrophage colony-stimulating factor-secreting allogeneic pancreatic tumor cells, induces T-cell immunity to cancer antigens, including mesothelin. GVAX is administered with low-dose cyclophosphamide (Cy) to inhibit regulatory T cells. CRS-207, live-attenuated Listeria monocytogenes-expressing mesothelin, induces innate and adaptive immunity. On the basis of preclinical synergy, we tested prime/boost vaccination with GVAX and CRS-207 in pancreatic adenocarcinoma. Previously treated patients with metastatic pancreatic adenocarcinoma were randomly assigned at a ratio of 2:1 to two doses of Cy/GVAX followed by four doses of CRS-207 (arm A) or six doses of Cy/GVAX (arm B) every 3 weeks. Stable patients were offered additional courses. The primary end point was overall survival (OS) between arms. Secondary end points were safety and clinical response. A total of 90 patients were treated (arm A, n = 61; arm B, n = 29); 97% had received prior chemotherapy; 51% had received ≥ two regimens for metastatic disease. Mean number of doses (± standard deviation) administered in arms A and B were 5.5 ± 4.5 and 3.7 ± 2.2, respectively. The most frequent grade 3 to 4 related toxicities were transient fevers, lymphopenia, elevated liver enzymes, and fatigue. OS was 6.1 months in arm A versus 3.9 months in arm B (hazard ratio [HR], 0.59; P = .02). In a prespecified per-protocol analysis of patients who received at least three doses (two doses of Cy/GVAX plus one of CRS-207 or three of Cy/GVAX), OS was 9.7 versus 4.6 months (arm A v B; HR, 0.53; P = .02). Enhanced mesothelin-specific CD8 T-cell responses were associated with longer OS, regardless of treatment arm. Heterologous prime/boost with Cy/GVAX and CRS-207 extended survival for patients with pancreatic cancer, with minimal toxicity.

ADXS11-001 immunotherapy targeting HPV-E7: final results from a Phase II study in Indian women with recurrent cervical cancer

Meeting abstracts ADXS11-001 immunotherapy is a live attenuated Listeria monocytogenes ( Lm ) bioengineered to secrete a tLLO-HPV-16-E7 fusion protein targeting HPV-transformed cells. The Lm vector serves as its own adjuvant and infects APC where it cross presents HPV-E7-tLLO fusion peptide,