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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. Cancer Immunol Res; 2(7); 616–31. ©2014 AACR.

Figure S1 Schema of the Neoadjuvant and Adjuvant Study of Panc GVAX. Figure S2 Pre- and post-vaccination mesothelin peptide-specific T cell levels in responders versus nonresponders. Figure S3 Intratumoral tertiary lymphoid aggregate in PDACs from patients treated with GVAX and lymphocyte cluster in PDACs from patients not treated with GVAX. Figure S4 The development of post-vaccination intratumoral lymphoid aggregates is associated with survival. Figure S5 Relatively more Granzyme B expressing cells observed outside of the lymphoid aggregates. Figure S6 Microdissection of Lymphoid Aggregates for Microarray Analysis. Figure S7 Microarray analysis of lymphoid aggregates revealed gene signatures in four pathways involved in regulating immune cell trafficking and function. Figure S8 Decreased Treg and increased TH17 pathway gene expression signatures are associated with improved post-vaccination responses. Figure S9 Downregulation of Treg pathway gene expression in TIL following treatment with PDAC GVAX is associated with longer survival. Figure S10 IL17A-producing T cells are present in low levels in TIL from PDAC GVAX treated patients. Figure S11 Treatment with low dose Cy increases post-vaccination densities of intratumoral lymphoid aggregates and reduces Treg levels in the PDAC TME. Figure S12 T cell infiltration in PDACs with low versus high CD8/Foxp3 ratio. Table S1 Immunohistochemistry protocols. Table S2 Quantitative real-time RT-PCR primers. Table S3 Scores of TH1, TH2, Treg, and TH17 pathway gene expression in PDAC TIL analyzed by quantitative real-time RT-PCR. Table S4 Numbers of TIL specimens with detectable expression of immune related genes.

Background: The bone marrow harbors tumor-antigen specific T cells in patients with breast cancer (1). Marrow-infiltrating lymphocytes (MILs®) are the product of activating and expanding bone-marrow T cells (2). In multiple myeloma, transfer of MILs as adoptive cell therapy has demonstrated anti-tumor activity (3). The use of adoptive transfer of autologous tumor-infiltrating lymphocytes (TILs) has been used successfully for hormone-receptor positive (HR+) metastatic breast cancer (4). Expansion of MILs was previously shown to be feasible in breast cancer, non-small cell lung cancer (NSCLC), prostate, head and neck, glioblastoma and multiple myeloma (5). Using an expanded cohort, we demonstrate that tumor-specific MILs can be expanded from bone marrow in patients with breast cancer. Methods: Bone marrow aspiration and blood samples were collected from 8 patients with metastatic and high-risk early-stage breast cancer, including 3 patients with HR+/HER2-, 2 patients with HER2+, and 3 patients with triple negative subtypes, at Providence Cancer Institute (Portland, OR). MILs and peripheral blood lymphocytes were activated and expanded from patient samples during a 10-day proprietary process. T cell lineage-specific markers CD3, CD4 and CD8 were characterized by flow cytometry pre- and post- expansion. Tumor-specific T cells were quantitated in expanded MILs and peripheral blood lymphocytes using a previously described cytokine-secretion assay (3). Briefly, they were defined as the IFNy-producing population by flow cytometry. Autologous antigen-presenting cells (APCs) were pulsed with lysates from allogeneic cancer cell lines and co-cultured with activated MILs or peripheral blood lymphocytes. APCs pulsed with irrelevant mis-matched cancer cell line lysates or media alone were used as negative controls. Results: In all harvested samples, MILs expansion successfully resulted in a selective increase in CD3+ T cells. Cytokine-producing CD4+ and CD8+ T cells were detected in all expanded MILs samples, but not in any of the matched activated and expanded peripheral blood lymphocytes. MILs were successfully expanded in HR+/HER2-, HER2+, and triple negative subtypes without apparent differences in activity as measured by cytokine production. Conclusion: MILs isolated from this expanded cohort of metastatic and high-risk early stage breast cancer patients demonstrated cytokine production in response to pulsed cancer cell line lysates, consistent with our experience with other solid (5) and hematological (3) malignancies. A phase II trial to evaluate MILs in combination with a checkpoint inhibitor is underway in patients with anti-PD1/PDL1-refractory NSCLC (NCT04069936). These preclinical data demonstrate that expanding MILs is feasible and could be evaluated therapeutically in breast cancer. References: 1. Feuerer M, Rocha M, Bai L, et al. Int J Cancer 2001; 92(1):96-105.2. Borrello I and Noonan KA. Marrow-Infiltrating Lymphocytes - Role in Biology and Cancer Therapy. Front Immunol 2016 March 30; 7(112)3. Noonan KA, Huff CA, Davis J, et al. Adoptive transfer of activated marrow-infiltrating lymphocytes induces measurable antitumor immunity in the bone marrow in multiple myeloma. Sci. Transl. Med 2015; 7:288ra784. Zacharakis N, Chinnasamy H, Black M, et al. Immune recognition of somatic mutations leading to complete durable regression in metastatic breast cancer. Nat Med. 2018; Jun (6): 724-730.5. Lutz E, Rudraraju L, DeOliveira E, et al. 154 Marrow-infiltrating lymphocytes (MILs): A novel adoptive immunotherapy for hematological and solid tumors. Journal for ImmunoTherapy of Cancer. 2020; 8. Citation Format: Brie Chun, Eric R Lutz, Lakshmi Rudraraju, Elizabeth DeOliveira, Amanda Seiz, Monil Shah, Ivan Borrello, Nicole E Fredrich, Kimberly Noonan, David B Page. Marrow-infiltrating lymphocytes as adoptive immunotherapy for breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-14-07.

Background Marrow infiltrating lymphocytes (MILsTM) are the product of activating and expanding bone marrow T cells.1 The bone marrow is a specialized niche in the immune system enriched for antigen-experienced, memory T cells. In patients with multiple myeloma and other hematological malignancies that relapse post-transplant, MILs have been shown to contain tumor antigen-specific T cells and adoptive cell therapy (ACT) using MILs has demonstrated antitumor activity.2 3 The bone marrow has been shown to harbor tumor-antigen specific T cells in patients with melanoma,4 5 glioblastoma,6 breast,7 non-small-cell lung8 and pancreatic cancers.9 Here, we sought to determine if tumor-specific MILs could be expanded from the bone marrow of patients with a range of different solid tumors. Methods Bone marrow and blood samples were collected from patients with advanced and metastatic cancers. To date, samples have been collected from a minimum of four patients with non-small cell lung cancer (NSCLC), prostate cancer, head and neck cancer, glioblastoma, and breast cancer. Samples from patients with multiple myeloma were used as a reference control. Utilizing a 10-day proprietary process, MILs and peripheral blood lymphocytes (PBLs) were activated and expanded from patient bone marrow and blood samples, respectively. T cell lineage-specific markers (CD3, CD4 and CD8) were characterized by flow cytometry pre- and post-expansion.Tumor-specific T cells were quantitated in expanded MILs and PBLs using a previously described cytokine-secretion assay [2]. Briefly, autologous antigen-presenting cells (APCs) were pulsed with lysates from allogeneic cancer cell lines and co-cultured with activated MILs or PBLs. APCs pulsed with irrelevant mis-matched cancer cell line lysates or media alone were used as negative controls. Tumor-specific T cells were defined as the IFNgamma-producing population by flow cytometry. Results MILs were successfully expanded from all patient bone marrow samples tested, regardless of tumor type. Cytokine-producing tumor-specific CD4+ and CD8+ T cells were detected in each of the expanded MILs. In contrast, tumor-specific T cells were not detected in any of the matched activated and expanded PBLs. Conclusions MILs have been successfully grown for all solid tumor types evaluated, including NSCLC, prostate, head and neck, glioblastoma and breast cancer. Clinical studies have been completed in patients with multiple myeloma and other hematological cancers. 2 3 A phase IIa trial to evaluate MILs in combination with a checkpoint inhibitor is underway in patients with anti-PD1/PDL1-refractory NSCLC (ClinicalTrials.gov Identifier: NCT04069936). The preclinical data presented herein demonstrate that expanding MILs is feasible. MILs-based therapies hold therapeutic promise across a wide range of tumor indications. Ethics Approval This study was approved by each participating instituion’s IRB. References Borrello I and Noonan KA. Marrow-Infiltrating Lymphocytes - Role in Biology and Cancer Therapy. Front Immunol 2016 March 30; 7(112) Noonan KA, Huff CA, Davis J, et al. Adoptive transfer of activated marrow-infiltrating lymphocytes induces measurable antitumor immunity in the bone marrow in multiple myeloma. Sci. Transl. Med 2015;7:288ra78. Biavati L, Noonan K, Luznik L, Borrello I. Activated allogeneic donor-derived marrow-infiltrating lymphocytes display measurable in vitro antitumor activity. J Immunother 2019 Apr;42(3):73–80. Muller-Berghaus J, Ehlert K, Ugurel S, et al. Melanoma-reactive T cells in the bone marrow of melanoma patients: association with disease stage and disease duration. Cancer Res 2006;66(12):5997–6001. Letsch A, Keilholz U, Assfalg G, et al., Bone marrow contains melanoma-reactive CD8+ effector T Cells and, compared with peripheral blood, enriched numbers of melanoma-reactive CD8+ memory T cells. Cancer Res 2003 Sep 1;63(17):5582–5586. Chongsathidkiet P, Jackson C, Koyama S, et al., Sequestration of T cells in bone marrow in the setting of glioblastoma and other intracranial tumors. Nature Medicine 2018 Aug 13; 24:1459–1468. Feuerer M, Rocha M, Bai L, et al. Enrichment of memory T cells and other profound immunological changes in the bone marrow from untreated breast cancer patients. Int J Cancer 2001; 92(1):96–105. Safi S, Yamauchi Y, Stamova S, et al. Bone marrow expands the repertoire of functional T cells targeting tumor-associated antigens in patients with resectable non-small-cell lung cancer. Oncoimmunology 2019;8(12):e1671762. Schmitz-Winnenthal FH, Volk C, Z’Graggen K, et al. High frequencies of functional tumor-reactive T cells in bone marrow and blood of pancreatic cancer patients. Cancer Res 2005;65(21):10079–87.

The past decade of cancer research has been marked by a growing appreciation of the role of immunity in cancer. Mutations in the tumour genome can cause tumours to express mutant proteins that are tumour specific and not expressed on normal cells (neoantigens). These neoantigens are an attractive immune target because their selective expression on tumours may minimize immune tolerance as well as the risk of autoimmunity. In this Review we discuss the emerging evidence that neoantigens are recognized by the immune system and can be targeted to increase antitumour immunity. We also provide a framework for personalized cancer immunotherapy through the identification and selective targeting of individual tumour neoantigens, and present the potential benefits and obstacles to this approach of targeted immunotherapy.

TPS9630 Background: Primary or secondary resistance to anti-PD-1 may be due to loss of T cell function. Persistent antigen stimulation can lead to impaired CD8+ T cell function, which often results in acquired resistance to PD-1 inhibition. It is unclear whether reinvigoration of tumor infiltrating cells or recruitment of novel T cells impart the activity of anti-PD-1 therapy. The bone marrow is a reservoir for antigen experienced memory T cells. We have previously shown that MILs can be generated for patients with hematologic malignancies and solid tumors including patients with NSCLC. MILs are the product of the activation and expansion of bone marrow T cells with a polyantigenic memory phenotype that recognize tumor antigens, are cytotoxic to autologous tumor and are able to persist over a long period of time. In a pre-clinical study of NSCLC, MILs were able to be expanded in all patients tested. Furthermore, all of the NSCLC products tested showed specificity to shared NSCLC antigens. The combination of adoptive cell therapy (ACT) with checkpoint inhibitors (CPIs) has distinctive positive effects on CD8 and CD4 T cell subsets, with the possibility for complete tumor control. We hypothesize that patients with NSCLC who have relapsed on anti-PD-1 treatment could benefit from an infusion of non-exhausted, central memory-enhanced, antigen specific T cells i.e. MILs which can delay the induction of tumor-associated anergy and augment the overall effectiveness of immunotherapy. Methods: Patients with advanced NSCLC who have progressed following prior anti-PD-1 therapy, with sufficient bone marrow reserve and an ECOG 0-1 are eligible. In eligible patients, bone marrow (200 mL) will be harvested and processed. Patients will undergo lymphodepletion (fludarabine 300 mg/m2/day and cyclophosphamide 30 mg/m2/day on days -5,-4,-3) followed by infusion of MILs on day 0. In Part 1, up to 6 patients will be administered MILs alone on day 0. In Part 2, approximately 20 subjects will be administered MILs on day 0 followed by NIVO 480 mg Q4W starting on day 1. The objectives of the study are to assess safety of MILs alone and in combination with NIVO, as well as efficacy. The first patient was treated in December 2019. Clinical trial information: NCT04069936 .

Tumor neoantigens arising from somatic mutations in the cancer genome are less likely to be subject to central immune tolerance and are therefore attractive targets for vaccine immunotherapy. We utilized whole-exome sequencing, RNA sequencing (RNASeq), and an in silico immunogenicity prediction algorithm, NetMHC, to generate a neoantigen-targeted vaccine, PancVAX, which was administered together with the STING adjuvant ADU-V16 to mice bearing pancreatic adenocarcinoma (Panc02) cells. PancVAX activated a neoepitope-specific T cell repertoire within the tumor and caused transient tumor regression. When given in combination with two checkpoint modulators, namely anti-PD-1 and agonist OX40 antibodies, PancVAX resulted in enhanced and more durable tumor regression and a survival benefit. The addition of OX40 to vaccine reduced the coexpression of T cell exhaustion markers, Lag3 and PD-1, and resulted in rejection of tumors upon contralateral rechallenge, suggesting the induction of T cell memory. Together, these data provide the framework for testing personalized neoantigen-based combinatorial vaccine strategies in patients with pancreatic and other nonimmunogenic cancers.

A series of NASA airborne lidars have been used in support of satellite laser altimetry missions. These airborne laser altimeters have been deployed for satellite instrument development, for spaceborne data validation, and to bridge the data gap between satellite missions. We used data from ground-based Global Positioning System (GPS) surveys of an 11 km long track near Summit Station, Greenland, to assess the surface–elevation bias and measurement precision of three airborne laser altimeters including the Airborne Topographic Mapper (ATM), the Land, Vegetation, and Ice Sensor (LVIS), and the Multiple Altimeter Beam Experimental Lidar (MABEL). Ground-based GPS data from the monthly ground-based traverses, which commenced in 2006, allowed for the assessment of nine airborne lidar surveys associated with ATM and LVIS between 2007 and 2016. Surface–elevation biases for these altimeters – over the flat, ice-sheet interior – are less than 0.12 m, while assessments of measurement precision are 0.09 m or better. Ground-based GPS positions determined both with and without differential post-processing techniques provided internally consistent solutions. Results from the analyses of ground-based and airborne data provide validation strategy guidance for the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) elevation and elevation-change data products.

BACKGROUND. Immune checkpoint inhibitors provide significant clinical benefit to a subset of patients, but novel prognostic markers are needed to predict which patients will respond. This study was initiated to determine if features of patient T cell repertoires could provide insights into the mechanisms of immunotherapy, while also predicting outcomes. METHODS. We examined T cell receptor (TCR) repertoires in peripheral blood of 25 metastatic pancreatic cancer patients treated with ipilimumab with or without GVAX (a pancreatic cancer vaccine), as well as peripheral blood and tumor biopsies from 32 patients treated with GVAX and mesothelin-expressing Listeria monocytogenes with or without nivolumab. Statistics from these repertoires were then tested for their association with clinical response and treatment group. RESULTS. We demonstrate that, first, the majority of patients receiving these treatments experience a net diversification of their peripheral TCR repertoires. Second, patients receiving ipilimumab experienced larger changes in their repertoires, especially in combination with GVAX. Finally, both a low baseline clonality and a high number of expanded clones following treatment were associated with significantly longer survival in patients who received ipilimumab but not in patients receiving nivolumab. CONCLUSIONS. We show that these therapies have measurably different effects on the peripheral repertoire, consistent with their mechanisms of action, and demonstrate the potential for TCR repertoire profiling to serve as a biomarker of clinical response in pancreatic cancer patients receiving immunotherapy. In addition, our results suggest testing sequential administration of anti–CTLA-4 and anti–PD-1 antibodies to achieve optimal therapeutic benefit. TRIAL REGISTRATION. Samples used in this study were collected from the {"type":"clinical-trial","attrs":{"text":"NCT00836407","term_id":"NCT00836407"}}NCT00836407 and {"type":"clinical-trial","attrs":{"text":"NCT02243371","term_id":"NCT02243371"}}NCT02243371 clinical trials. FUNDING. Research supported by a Stand Up To Cancer Lustgarten Foundation Pancreatic Cancer Convergence Dream Team Translational Research grant (SU2C-AACR-DT14-14). Stand Up To Cancer is a program of the Entertainment Industry Foundation administered by the American Association for Cancer Research (AACR). Additional clinical trial funding was provided by AACR-Pancreatic Cancer Action Network Research Acceleration Network grant (14-90-25-LE), NCI SPORE in GI Cancer ({"type":"entrez-nucleotide","attrs":{"text":"CA062924","term_id":"24393167","term_text":"CA062924"}}CA062924), Quick-Trials for Novel Cancer Therapies: Exploratory Grants (R21CA126058-01A2), and the US Food and Drug Administration (R01FD004819). Research collaboration and financial support were provided by Adaptive Biotechnologies.

Purpose 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. Patients and Methods 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. Results 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. Conclusion Heterologous prime/boost with Cy/GVAX and CRS-207 extended survival for patients with pancreatic cancer, with minimal toxicity.

Pancreatic ductal adenocarcinoma (PDA) has a poor prognosis due to late detection and resistance to conventional therapies. Published studies show that the PDA tumor microenvironment is predominantly infiltrated with immune suppressive cells and signals that if altered, would allow effective immunotherapy. However, single-agent checkpoint inhibitors including agents that alter immune suppressive signals in other human cancers such as cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed death 1 (PD-1), and its ligand PD-L1, have failed to demonstrate objective responses when given as single agents to PDA patients. We recently reported that inhibition of the CTLA-4 pathway when given together with a T cell inducing vaccine gives objective responses in metastatic PDA patients. In this study, we evaluated blockade of the PD-1/PD-L1 pathway. We found that PD-L1 is weakly expressed at a low frequency in untreated human and murine PDAs but treatment with a granulocyte macrophage colony-stimulating factor secreting PDA vaccine (GVAX) significantly upregulates PD-L1 membranous expression after treatment of tumor-bearing mice. In addition, combination therapy with vaccine and PD-1 antibody blockade improved murine survival compared with PD-1 antibody monotherapy or GVAX therapy alone. Furthermore, PD-1 blockade increased effector CD8 T lymphocytes and tumor-specific interferon-γ production of CD8 T cells in the tumor microenvironment. Immunosuppressive pathways, including regulatory T cells and CTLA-4 expression on T cells were overcome by the addition of vaccine and low-dose cyclophosphamide to PD-1 blockade. Collectively, our study supports combining PD-1 or PD-L1 antibody therapy with a T cell inducing agent for PDA treatment.

See related article by Fritsch et al., [p. 522][1] Most human cancers acquire tens to hundreds of somatic mutations (termed the “tumor mutome”) during their development ([1][2]). Each of these mutations has the potential to generate one or more novel T-cell antigens (termed “neoepitopes”)

Accumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along the 1009 km route of the Greenland Inland Traverse from Thule to Summit during April and May of 2011, to image continuous internal reflecting horizons. We dated these horizons using ice-core chemistry at each end of the traverse. Using density profiles measured along the traverse, we determined the depth to the horizons and the corresponding water-equivalent accumulation rates. The measured accumulation rates vary from ~0.1 m w.e. a–1 in the interior to ~0.7 m w.e. a–1 near the coast, and correspond broadly with existing published model results, though there are some excursions. Comparison of our recent accumulation rates with those collected along a similar route in the 1950s shows a ~10% increase in accumulation rates over the past 52 years along most of the traverse route. This implies that the increased water vapor capacity of warmer air is increasing accumulation in the interior of Greenland.

Here we describe a multiplexed immunohistochemical platform, with computational image processing workflows including image cytometry, enabling simultaneous evaluation of 12 biomarkers in one formalin-fixed paraffin-embedded tissue section. To validate this platform, we used tissue microarrays containing 38 archival head and neck squamous cell carcinomas, and revealed differential immune profiles based on lymphoid and myeloid cell densities, correlating with human papilloma virus status and prognosis. Based on these results, we investigated 24 pancreatic ductal adenocarcinomas from patients who received neoadjuvant GVAX vaccination, and revealed that response to therapy correlated with degree of mono-myelocytic cell density, and percentages of CD8+ T cells expressing T cell exhaustion markers. These data highlight the utility of in situ immune monitoring for patient stratification, and provide digital image processing pipelines (https://github.com/multiplexIHC/cppipe) to the community for examining immune complexity in precious tissue sections, where phenotype and tissue architecture are preserved to thus improve biomarker discovery and assessment.

Background The type of T cell used in generating chimeric antigen receptor (CAR) T cells is an important choice. Evidence suggests that T cells that are early in the effector/memory differentiation pathway with more stemness and greater potential to persist are better than more differentiated T cells with less stemness that are more readily exhausted and have less potential to persist. Marrow-infiltrating Lymphocytes (MILsTM) is a novel form of adoptive T cell therapy composed of patient-autologous, polyclonal CD4 and CD8 T cells that are activated and expanded from the bone marrow. Genetically unmodified MILsTM have demonstrated antitumor activity in patients with multiple myeloma and are being developed for several other tumor types, including non-small cell lung cancer and other solid tumors. Distinguishing features of bone marrow T cells used to produce MILsTM include their memory phenotype, inherent tumor antigen-specificity, higher CD8:CD4 ratio and ability to persist long-term when compared to peripheral blood lymphocytes (PBLs) which is the T cell source used to produce currently approved CAR-T therapies. Based on these differences, we hypothesize that MILsTM provide a more robust and better fit platform for CAR-T therapy compared to PBLs. Using a CD38-specific, 4-1BB/CD3z-signaling CAR as an initial model, we have demonstrated the feasibility of producing CAR-modified MILsTM (CAR-MILsTM) and showed that CAR-MILsTM demonstrate superior killing in vitro compared to CAR-T cells generated from patient-matched PBLs (CAR-PBLs). Herein, we build on our previous data and add a second BCMA-specific CAR model. We use the two multiple myeloma model systems to compare cytolytic potential, functionality, and expression of phenotypic markers of memory, stemness and exhaustion between patient-matched CAR-MILsTM and CAR-PBLs. Methods Matched pairs of CAR-MILsTM and CAR-PBLs were produced from the bone marrow and blood of multiple myeloma patients. Two different in vitro cytotoxicity assays, the RTCA xCelligence real-time impedance and FACS assays, were used to evaluate antigen-specific killing of target tumor cells. Functionality of CD4 and CD8 CAR-T cells, at the single-cell level, was evaluated by measuring the secretion of 32 cytokines and chemokines following in vitro antigen-specific stimulation using IsoPlexis IsoCode chips and analyzed using IsoPeak. Expression of markers of T cell memory (CD45RO & CCR7/CD62L), stemness (CD27) and exhaustion (PD1 & TIM3) on CAR-MILsTM and CAR-PBLs prior to and following antigen-specific stimulation was evaluated by flow-cytometry (FACS). Results CAR-MILsTM demonstrated superior killing of tumor target cells in vitro, regardless of the antigen specificity of the CAR, when compared to matched CAR-PBLs and this superiority persisted even upon repeated antigen encounter - a factor that may be critical in guaranteeing better anti-tumor efficacy and persistence. CAR-MILsTM demonstrated increased polyfunctionality (secretion of 2+ cytokines per cell) and an increased polyfunctional strength index (PSI) following antigen-stimulation compared to CAR-PBL in both CD4 and CD8 T cells. The enhanced PSI in CAR-MILsTM was predominately mediated by effector, stimulatory and chemoattractive proteins associated with antitumor activity including Granzyme B, IFNg, IL-8, MIP1a and MIP1b. Coincidentally, increased PSI and enhanced secretion of these same proteins was reported to be associated with improved clinical responses in patients with Non-Hodgkin lymphoma treated with CD19-specific CAR-T therapy. Expression of memory markers on CD4 and CD8 T cells were similar in CAR-MILsTM and CAR-PBLs both prior to and following antigen-stimulation. Although expression of CD27, PD1 and TIM3 were similar at baseline, CAR-MILs maintained higher levels of CD27 and lower levels of PD1 and TIM3 compared to CAR-PBLs following antigen-stimulation in both CD4 and CD8 T cells. Conclusions Collectively, our data suggest that CAR-MILsTM have several advantages over CAR-PBLs, including increased cytolytic potential, enhanced polyfunctionality, increased stemness and less exhaustion. Based on these differences and the inherent antitumor properties of MILsTM, we speculate that CAR-MILsTM would be more potent and effective than currently approved CAR-T products derived from PBLs. Disclosures Lutz: WindMIL Therapeutics: Employment, Equity Ownership. Jana:WindMIL Therapeutics: Employment, Equity Ownership. Rudraraju:WindMIL Therapeutics: Employment, Equity Ownership. DeOliveira:WindMIL Therapeutics: Employment, Equity Ownership. Zhou:Isoplexis: Employment, Equity Ownership. Mackay:Isoplexis: Employment, Equity Ownership. Borrello:Aduro: Patents & Royalties: intellectual property on allogeneic MM GVAX; BMS: Consultancy; WindMIL Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau. Noonan:WindMIL Therapeutics: Employment, Equity Ownership, Patents & Royalties; Aduro: Patents & Royalties: intellectual property on allogeneic MM GVAX.

Preclinical reports support the concept of synergy between cancer vaccines and immune checkpoint blockade in nonimmunogenic tumors. In particular, cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) antibodies have been successfully combined with GM-CSF cell-based vaccines (GVAX). Ipilimumab (anti-CTLA-4) has been tested as a single agent in patients with pancreatic ductal adenocarcinoma (PDA) resulting in a delayed response at a dose of 3 mg/kg. Our study evaluated ipilimumab 10 mg/kg (arm 1) and ipilimumab 10 mg/kg + GVAX (arm 2). A total of 30 patients with previously treated advanced PDA were randomized (1:1). Induction doses were administered every 3 weeks for a total of 4 doses followed by maintenance dosing every 12 weeks. Two patients in arm 1 showed evidence of stable disease (7 and 22 wk) but none demonstrated CA19-9 biochemical responses. In contrast, 3 patients in arm 2 had evidence of prolonged disease stabilization (31, 71, and 81 wk) and 7 patients experienced CA19-9 declines. In 2 of these patients, disease stabilization occurred after an initial period of progression. The median overall survival (OS) (3.6 vs. 5.7 mo, hazards ratio: 0.51, P = 0.072) and 1 year OS (7 vs. 27%) favored arm 2. Similar to prior ipilimumab studies, 20% of patients in each arm had grade 3/4 immune-related adverse events. Among patients with OS4.3 months, there was an increase in the peak mesothelin-specific T cells (P = 0.014) and enhancement of the T-cell repertoire (P = 0.031). In conclusion, checkpoint blockade in combination with GVAX has the potential for clinical benefit and should be evaluated in a larger study.

Surface melt on a glacier can perturb the glaciochemical record beyond the natural variability. While the centre of the Greenland ice sheet is usually devoid of surface melt, many high-Arctic and alpine ice cores document frequent summertime melt events. Current hypotheses interpreting melt-affected ice-core chemistry rely on preferential elution of certain major ions. However, the precise nature of chemistry alteration is unknown because it is difficult to distinguish natural variability from melt effects in a perennially melt-affected site. We use eight trace-element snow chemistry records recovered from Summit, Greenland, to study spatial variability and melt effects on insoluble trace chemistry and physical stratigraphy due to artificially introduced meltwater. Differences between non-melt and melt-affected chemistry were significantly greater than the spatial variability in chemistry represented by nearest-neighbour pairs. Melt-perturbed trace elements, particularly rare earth elements, retained their seasonal stratigraphies, suggesting that trace elements may serve as robust chemical indicators for annual layers even in melt-affected study areas. Results suggest trace-element transport via meltwater percolation will deposit eluted material down-pit in refrozen areas below the nearest-surface chemistry peak. In our experiments, snow chemistry analyses are more sensitive to melt perturbations than density changes or unprocessed near-infrared digital imagery.

Cancer vaccines, in order to be successful, must generate tumor-specific CD8 + T cells that can effectively traffic to the tumor microenvironment (TME) and maintain their activity in the immunosuppressive TME. T cell avidity and priming are critical components of an effective vaccine response, but the immunosuppressive environment of the tumor may still inhibit optimal T cell function. The addition of immune checkpoint inhibitors to existing cancer vaccines has been associated with an effective T cell response that translates into prolonged survival. This article will examine the components necessary to induce a potent and effective CD8 + T cell response using combination vaccine immunotherapies.

Purpose: Listeria monocytogenes (Lm)-based vaccines stimulate both innate and adaptive immunity. ANZ-100 is a live-attenuated Lm strain (Lm ΔactA/ΔinlB). Uptake by phagocytes in the liver results in local inflammatory responses and activation and recruitment of natural killer (NK) and T cells, in association with increased survival of mice bearing hepatic metastases. The Lm ΔactA/ΔinlB strain, engineered to express human mesothelin (CRS-207), a tumor-associated antigen expressed by a variety of tumors, induces mesothelin-specific T-cell responses against mesothelin-expressing murine tumors. These two phase I studies test ANZ-100 and CRS-207 in subjects with liver metastases and mesothelin-expressing cancers, respectively. Experimental Design: A single intravenous injection of ANZ-100 was evaluated in a dose escalation study in subjects with liver metastases. Nine subjects received 1 × 106, 3 × 107, or 3 × 108 colony-forming units (cfu). CRS-207 was evaluated in a dose-escalation study in subjects with mesothelioma, lung, pancreatic, or ovarian cancers. Seventeen subjects received up to 4 doses of 1 × 108, 3 × 108, 1 × 109, or 1 × 1010 cfu. Results: A single infusion of ANZ-100 was well tolerated to the maximum planned dose. Adverse events included transient laboratory abnormalities and symptoms associated with cytokine release. Multiple infusions of CRS-207 were well tolerated up to 1 × 109 cfu, the determined maximum tolerated dose. Immune activation was observed for both ANZ-100 and CRS-207 as measured by serum cytokine/chemokine levels and NK cell activation. In the CRS-207 study, listeriolysin O and mesothelin-specific T-cell responses were detected and 37% of subjects lived ≥15 months. Conclusions: ANZ-100 and CRS-207 administration was safe and resulted in immune activation. Clin Cancer Res; 18(3); 858–68. ©2011 AACR.

Adoptive cellular immunotherapy (ACT) using chimeric-antigen receptor (CAR)-modified T cells has shown unprecedented initial response rates in patients with advanced B cell malignancies and is emerging as a powerful tool for cancer treatment. However, there remains room for improvement in initial response rates, and relapse occurs in a significant fraction of those patients that do respond. Reasons for failure to respond are being elucidated. At least two mechanism of relapse - lack of persistence of infused CAR-T cells and the loss of antigen-expression by tumor cells - are well documented. We have developed a novel platform for ACT called Marrow-infiltrating Lymphocytes (MILs). MILs are a population of polyclonal T cells expanded from the bone marrow (BM) with distinct properties that set them apart from T cells expanded from peripheral blood lymphocytes (PBLs). MILs are enriched with memory T cells and contain tumor antigen-specific T cells that are typically not detected in PBLs. MILs are being developed for several tumor types, including both hematological and solid tumors. Distinguishing features of MILs compared to PBLs include their memory phenotype, inherent tumor antigen-specificity, and ability to persist long-term. As such, we hypothesized that MILs would provide a robust platform for CAR-T cell therapy with the potential to boost initial response rates and reduce the risk of relapse. Herein, data is presented demonstrating superior anti-tumor activity of CAR-modified MILs (CAR-MILs) compared to CAR-T cells generated from patient-matched PBLs (CAR-PBLs). We designed a 2nd generation 4-1BB-CD3z CD38 CAR using an scFv derived from Daratumumab. The CD38 CAR was linked to GFP by a T2a cleavage peptide so that GFP could be used as a marker of CAR expression. The CD38 CAR was expressed in a lentiviral construct and demonstrated equal transduction efficiencies and CAR expression levels in MILs and PBLs. The CAR modified MILs demonstrated superior antigen specific killing compared to PBLs against the 8226 myeloma (MM) cell line but not its isogenic CD38 knocked out line. More importantly, CAR-MILs retained their inherent tumor antigen-specificity and capacity to respond through their endogenous tumor antigen-specific T cell receptors - a property that PBL-CARs did not appear to possess. Tumor antigen-specific T cells were quantified by co-culturing MILs with autologous antigen-presenting cells pulsed with allogeneic multiple myeloma cell line lysates as a source of antigen and measuring IFNγ-production as a read-out. An equal or greater number of tumor antigen-specific IFNγ-producing T cells were measured in CD38 CAR-MILs compared to matched unmodified MILs. Finally, we compared the in vitro cytolytic potential of CD38 CAR-MILs to matched CD38 CAR-PBLs. Co-culture killing assays were performed at decreasing CAR-T effector: target (E:T) ratios. At high E:T ratios, CAR-MILs and CAR-PBLs lysed comparable percentages of CD38+ targets with similar kinetics. However, at lower E:T ratios, CAR-MILs killed a greater percentage of CD38+ targets with faster kinetics compared to CAR-PBLs. In conclusion, we have demonstrated 1) the feasibility of producing CAR-modified MILs, 2) that CAR-MILs retain their inherent tumor antigen-specificity and functional capacity - something that was lacking with CAR-PBLs, and 3) that CAR-MILs kill more efficiently in vitro than matched CAR-PBLs. These data suggest that CAR-MILs may provide both better antigen specific killing but more importantly by targeting the endogenous antigenic repertoire, they could also prevent or minimize the risk of relapse via antigen escape variants and thus increase the overall efficacy of adoptive CAR T cell therapy. Disclosures Lutz: WIndMIL Therapeutics: Employment, Patents & Royalties. Rudraraju:WIndMIL Therapeutics: Employment. DeOliveira:WIndMIL Therapeutics: Employment. Jana:WIndMIL Therapeutics: Employment. Weiss:WIndMIL Therapeutics: Employment. Borrello:WIndMIL Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Noonan:WIndMIL Therapeutics: Employment, Equity Ownership, Patents & Royalties.

Purpose: The combination of chemotherapy and immunotherapy has not been examined in patients with advanced pancreatic cancer. We conducted a study of two granulocyte macrophage colony-stimulating factor–secreting pancreatic cancer cell lines (CG8020/CG2505) as immunotherapy administered alone or in sequence with cyclophosphamide in patients with advanced pancreatic cancer. Experimental Design: This was an open-label study with two cohorts: cohort A, 30 patients administered a maximum of six doses of CG8020/CG2505 at 21-day intervals; and cohort B, 20 patients administered 250 mg/m2 of cyclophosphamide i.v. 1 day before the same immunotherapy given as in cohort A. The primary objective was to evaluate safety and duration of immunity. Secondary objectives included time to disease progression and median overall survival. Results: The administration of CG8020/CG2505 alone or in sequence with cyclophosphamide showed minimal treatment-related toxicity. Median survival values in cohort A and cohort B were 2.3 and 4.3 months, respectively. CD8+ T-cell responses to HLA class I–restricted mesothelin epitopes were identified predominantly in patients treated with cyclophosphamide + CG8020/CG2505 immunotherapy. Conclusion: Granulocyte macrophage colony-stimulating factor–secreting pancreatic cancer cell lines CG8020/CG2505 alone or in sequence with cyclophosphamide showed minimal treatment-related toxicity in patients with advanced pancreatic cancer. Also, mesothelin-specific T-cell responses were detected/enhanced in some patients treated with CG8020/CG2505 immunotherapy. In addition, cyclophosphamide-modulated immunotherapy resulted in median survival in a gemcitabine-resistant population similar to chemotherapy alone. These findings support additional investigation of cyclophosphamide with CG8020/CG2505 immunotherapy in patients with advanced pancreatic cancer.

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.

T cell costimulation via OX40 is known to increase CD4+ T cell expansion and effector function and enhances the development of T cell memory. OX40 costimulation can also prevent, and even reverse, CD4+ T cell anergy. However, the role of OX40 in CD8+ T cell function is less well defined, particularly in the setting of immune tolerance. To determine the effects of OX40 costimulation on the induction of the host CD8+ T cell repertoire to an endogenous tumor Ag, we examined the fate of CD8+ T cells specific for the immunodominant rat HER-2/neu epitope, RNEU420–429, in FVB MMTV-neu (neu-N) mice, which express rat HER-2/neu protein in a predominantly mammary-restricted fashion. We show that the RNEU420–429-specific T cell repertoire in neu-N mice expands transiently after vaccination with a neu-targeted GM-CSF-secreting whole-cell vaccine, but quickly declines to an undetectable level. However, OX40 costimulation, when combined with GM-CSF-secreting tumor-targeted vaccination, can break established CD8+ T cell tolerance in vivo by enhancing the expansion, and prolonging the survival and effector function of CD8+ T cells specific for RNEU420–429. Moreover, we demonstrate that OX40 expression is up-regulated on both CD4+ and CD8+ T cells shortly after administration of a GM-CSF expressing vaccine. These studies highlight the increased efficacy of OX40 costimulation when combined with a GM-CSF-secreting vaccine, and define a new role for OX40 costimulation of CD8+ T cells in overcoming tolerance and boosting antitumor immunity.

Tumor-specific CD8+ T cells can potentially be activated by two distinct mechanisms of major histocompatibility complex class I–restricted antigen presentation as follows: direct presentation by tumor cells themselves or indirect presentation by professional antigen-presenting cells (APCs). However, controversy still exists as to whether indirect presentation (the cross-priming mechanism) can contribute to effective in vivo priming of tumor-specific CD8+ T cells that are capable of eradicating cancer in patients. A clinical trial of vaccination with granulocyte macrophage–colony stimulating factor–transduced pancreatic cancer lines was designed to test whether cross-presentation by locally recruited APCs can activate pancreatic tumor-specific CD8+ T cells. Previously, we reported postvaccination delayed-type hypersensitivity (DTH) responses to autologous tumor in 3 out of 14 treated patients. Mesothelin is an antigen demonstrated previously by gene expression profiling to be up-regulated in most pancreatic cancers. We report here the consistent induction of CD8+ T cell responses to multiple HLA-A2, A3, and A24-restricted mesothelin epitopes exclusively in the three patients with vaccine-induced DTH responses. Importantly, neither of the vaccinating pancreatic cancer cell lines expressed HLA-A2, A3, or A24. These results provide the first direct evidence that CD8 T cell responses can be generated via cross-presentation by an immunotherapy approach designed to recruit APCs to the vaccination site.

This study aims to translate tumor-specific mutations identified by next-generation sequencing techniques into an effective anti-tumor vaccine for a classically non-immunogenic tumor, pancreatic ductal adenocarcinoma (PDA). Pancreatic ductal adenocarcinomas develop an average of 63 mutations during tumorigenesis, collectively referred to as the “mutome.” Of these, approximately 45 are amino acid point mutations. These mutations are not present in normal cells and provide a source of tumor-specific neoepitopes for targeted immunotherapy. Next-generation sequencing technologies allow for rapid identification of mutations present in patient tumors; however, methods for rapid identification of immunogenic neoepitopes which can be effectively targeted for tumor clearance, and optimized vaccination strategies for targeting them, still need to be developed. In this study, we are using a transplantable murine PDA model, Panc02, to develop vaccination strategies for inducing neoepitope-specific T cell antitumor responses, and to define parameters for selecting appropriate targets. Exome sequencing identified 878 nonsynonymous mutations in the Panc02 cell line. Three immunological epitope prediction servers identified 878 potentially immunogenic peptides in the Panc02 model, 29 of which were strong candidates (scores Citation Format: Heather Kinkead, Eric Lutz, Thomas W. Dubensky, Elizabeth Jaffee. Exploiting the pancreatic cancer mutome for immune interception [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1695. doi:10.1158/1538-7445.AM2017-1695

Cancer immunotherapy is a rapidly developing field, but limited in its success by a high tumor burden and immune tolerance. In contrast, immunoprevention has the potential to prevent cancer before the development of immune tolerance, and to prevent cancer recurrence in the setting of minimal residual disease. Although immunoprevention for viral-induced cancers has been successful in the setting of hepatitis B and human papillomavirus vaccination, primary prevention of nonviral-induced cancers is in its infancy. In contrast, prevention of cancer recurrence after adjuvant treatment (secondary prevention) is gaining steam. This review provides an overview of the scope of research in cancer immunoprevention over the last three years and directions for future research. See all articles in this Cancer Prevention Research collection, “Cancer Immunoprevention Series.” Cancer Prev Res; 7(11); 1072–80. ©2014 AACR.

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. Cancer Immunol Res; 2(7); 616–31. ©2014 AACR.

Hallmarks of effective adoptive T cell therapy include: 1) the ability to access and expand T cells of interest 2) measurable anti-tumor efficacy of these cells upon reinfusion and 3) T cell persistence over time. In examining the long-term follow-up of patients treated with MILs, we show evidence of persistence of adoptively transferred MILs for over five years post transfer. In a clinical trial conducted in 2007, Prevnar naïve myeloma patients were immunized against the modified diphtheria toxin, CRM197 with the Prevnar vaccine administered 2 weeks prior to collecting marrow infiltrating lymphocytes (MILs) from bone marrow. Patients received a CD34-selected (T cell depleted) autologous stem cell transplant (SCT) and had activated and expanded MILs infused 3 days later. As such, 99% of infused T cells were Prevnar-primed, ex vivo expanded MILs. This approach enabled us to track the fate of the non gene-modified MILs by examining CRM197 specific T cells. As originally reported, persistence at one year of both CRM197 and myeloma antigen-specific T cells correlated with clinical responses.1 Long-term follow up was performed in a subset of the patients that had undergone bone marrow biopsies for clinical purposes. The results showed that patients who had been in a complete response at the end of the clinical trial maintained a greater number of both CRM197 and myeloma antigen-specific T cells over time for up to 7 years after the clinical trial. Patients who did not achieve a complete response and subsequently relapsed showed a loss of both CRM197 as well as myeloma antigen- specific T cells in most cases. Considering that the patients received a T cell depleted stem cell graft, the CRM197-specific T cells that were measured were likely a result of the Prevnar-primed MILs. From these results, we conclude that: 1) adoptively transferred CRM-197 specific MILs showed persistence up 7 years following their infusion. 2) the magnitude of CRM197 and myeloma antigen-specific T cell responses correlated with clinical responsiveness. Taken together, these data demonstrate several unique attributes of MILs which are critical for successful adoptive T cell therapyAdoptive transfer of activated marrow-infiltrating lymphocytes induces measurable antitumor immunity in the bone marrow in multiple myeloma. Noonan KA, Huff CA, Davis J, Lemas MV, Fiorino S, Bitzan J, Ferguson A, Emerling A, Luznik L, Matsui W, Powell J, Fuchs E, Rosner GL, Epstein C, Rudraraju L, Ambinder RF, Jones RJ, Pardoll D, Borrello I. Sci Transl Med. 2015 May 20;7(288). Disclosures Noonan: WindMIL Therapeutics: Employment, Equity Ownership, Patents & Royalties. Rudraraju:WindMIL Therapeutics: Employment, Equity Ownership. Lutz:WindMIL Therapeutics: Employment, Equity Ownership. Borrello:BMS: Honoraria, Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau; WindMIL Therapeutics: Equity Ownership, Patents & Royalties, Research Funding.

A major obstacle to the development of immunotherapy for pancreatic ductal adenocarcinoma (PDA) has been identifying immune relevant antigens that are not expressed by normal cells. DNA sequencing technologies that allow for the genome-wide identification of tumor mutations have shown that human PDAs harbor an average of 63 mutations (called the “mutome”). Since these mutations are not present prior to the onset of tumorigenesis, each mutation generates a novel and essentially foreign antigen (termed “epitope”). Unlike most classical tumor epitopes, mutome-derived epitopes are uniquely specific to each patient’s tumor. Furthermore, T cells recognizing them may avoid immunological tolerance mechanisms that inhibit or deplete T cells that recognize classical tumor epitopes that are also expressed by normal cells. Vaccines designed to activate mutome-specific T cells have the potential to induce robust and specific antitumor responses and provide a new approach for personalized tumor immunotherapy. We are using the Panc02 murine PDA model to develop and explore the potential of this approach. Sequence analysis identified 596 point mutations in Panc02 cells, significantly more than the number found in human PDAs. The NetMHC prediction server was used to screen for epitopes predicted to bind H2-Db and H2-Kb. In total, 15 strong candidates (NetMHC scores 100 spots per 1x105 T cells). Antitumor efficacy was evaluated by immunizing mice 3 days following subcutaneous Panc02 challenge. Only immunization against the 5 robust peptides was capable of preventing tumor outgrowth, and was significantly more effective than treatment with GM-CSF-secreting whole-cell vaccination (GVAX), another approach currently being investigated in the clinic by our group. We are currently testing the efficacy of this approach against larger established tumors and metastatic liver lesions. We are also working to optimize this approach by testing additional adjuvants and vaccine vectors, including recombinant Listeria monocytogenes that express the mutant gene sequences. Exact epitopes are being mapped in order to evaluate the utility of MHC-binding predictions. Ultimately, we intend to translate our optimized approach into the clinic.

TPS3626Background: Pembrolizumab has been shown to result in compelling responses and progression free survival in advanced MMR-d CRC. However, the vast majority (~95%) of patients with advanced CR...

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.

[1] Long-term streamflow reconstructions help characterize climate variability and extreme climatic events, such as droughts, which play a crucial role in water resource planning. Dendrohydrological reconstructions generally build on indirect associations between streamflow and radial tree growth, both of which depend on cool season precipitation in the Pacific Northwest. We develop a new approach that integrates a tree ring reconstruction of cool season precipitation with historical meteorological data and a physically based hydrologic model to reconstruct warm season streamflow and streamflow uncertainty. The Upper Yakima Basin in Washington state is used as a test case. We applied objective screening, principal components analysis, and multiple linear regression to reconstruct 366 years of basin-average cool season precipitation. The reconstruction was integrated with five temporally and spatially distributed cool season precipitation patterns spanning the historical range of natural variability. These distributed meteorological reconstructions were used as inputs to the Variable Infiltration Capacity (VIC) hydrologic model over the Yakima basin to produce an ensemble of warm season streamflows for each reconstructed year. The resultant streamflow reconstruction retains dendroclimatic information and quantifies the inherent uncertainty in warm season streamflow associated with historical meteorology. Finally, the meteorological reconstructions were systematically perturbed and used to drive the VIC to examine the potential impacts of climate change on warm season streamflow over the 366-year record. Despite projected wetter conditions in the future, less precipitation is stored as snowpack (due to warmer winter temperatures) and consequently warm season streamflow will be systematically reduced. The combination of long records of variability and systematic changes related to climate change provides useful information about the combined effects of natural variability and projected systematic changes in climate to support 21st-century water planning.

Purpose: Surgical resection provides the only possibility of cure for pancreas cancer. A standard adjuvant approach has not been established. We tested the safety and efficacy of a granulocyte-macrophage colony-stimulating factor (GM-CSF)-based immunotherapy administered in patients with resected pancreatic adenocarcinoma. Patients andMethods: A single institution phase II study of 60 patients with resected pancreatic adenocarcinoma was performed. Each immunotherapy treatment consisted of a total of 5 × 108GM-CSF-secreting cells distributed equally among 3 lymph node regions. The first immunotherapy treatment was administered 8 to 10 weeks after surgical resection. Subsequently, patients received 5-FU based chemoradiation. Patientswho remained disease-free after completion of chemoradiotherapy received treatments 2 to 4, each 1 month apart. A fifth and final booster was administered 6 months after the fourth immunotherapy.The primary endpointwas disease free survival and secondary endpoints were overall survival and toxicity, and the induction of mesothelinspecific T cell responses. Results: Themedian disease-free survival is 17.3months (95% CI, 14.6-22.8) with median survival of 24.8 months (95% CI, 21.2-31.6). The administration of immunotherapy was well tolerated. In addition, the postimmunotherapy induction of mesothelin-specific CD8+ T cells in HLA-A1+ and HLA-A2+ patients correlates with disease-free survival. Conclusions: An immunotherapy approach integrated with chemoradiation is safe and demonstrates an overall survival that compares favorably with published data for resected pancreas cancer. These data suggest additional boost immunotherapies given at regular intervals beyond 1 year postsurgery should be tested in future studies, and provide the rationale for conducting a multicenter phase II study. Copyright © 2011 by Lippincott Williams & Wilkins.

Tissue-derived adenosine, acting via the adenosine A(2A) receptor (A(2A)R), is emerging as an important negative regulator of T-cell function. In this report, we demonstrate that A(2A)R stimulation not only inhibits the generation of adaptive effector T cells but also promotes the induction of adaptive regulatory T cells. In vitro, antigen recognition in the setting of A(2A)R engagement induces T-cell anergy, even in the presence of costimulation. T cells initially stimulated in the presence of an A(2A)R agonist fail to proliferate and produce interleukin-2 and interferon (IFN)-gamma when rechallenged in the absence of A(2A)R stimulation. Likewise, in an in vivo model of autoimmunity, tissue-derived adenosine promotes anergy and abrogates tissue destruction. Indeed, A(2A)R stimulation inhibits interleukin-6 expression while enhancing the production of transforming growth factor-beta. Accordingly, treating mice with A(2A)R agonists not only inhibits Th1 and Th17 effector cell generation but also promotes the generation of Foxp3(+) and LAG-3(+) regulatory T cells. In this regard, A(2A)R agonists fail to prevent autoimmunity by LAG-3(-/-) clonotypic T cells, implicating an important role for LAG-3 in adenosine-mediated peripheral tolerance. Overall, our findings demonstrate that extracellular adenosine stimulates the A(2A)R to promote long-term T-cell anergy and the generation of adaptive regulatory T cells.

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

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.

HER-2/neu is overexpressed in several cancers including 30% of breast carcinomas, and correlates with a poor outcome. HER-2/neu-transgenic (neu-N) mice that overexpress the non-transforming rat neu develop spontaneous mammary carcinomas and demonstrate immunotolerance to the neu protein similar to that observed in patients with neu-expressing cancers. In neu-N mice, neu-targeted vaccination induces weak T cell and negligible Ab responses sufficient to delay but not eradicate transplanted neu-expressing tumor. Here we demonstrate that passive infusion of neu-specific mAbs in sequence with whole cell vaccination significantly improves tumor-free survival over either modality alone. Importantly, treatment of neu-N mice with vaccine in combination with two distinct neu-specific Abs is particularly efficacious, preventing tumor in 70% and eradicating established tumor in 30% of neu-N mice. In vivo lymphocyte subpopulation depletion experiments demonstrate that the efficacy of Ab, alone or combined with vaccine, is dependent on both CD4+ and CD8+ T cells. Furthermore, the in vivo antitumor effects of vaccine and Ab are associated with a significant increase in the number and function of neu-specific CD8+ T cells. Collectively, these observations suggest that similarly increased efficacy could be obtained by combining neu-targeted vaccination and neu-specific Abs such as trastuzumab (Herceptin) in patients with neu-expressing cancers.

Single agent immunotherapy is effective against several cancers, but has failed against poorly immunogenic cancers, including pancreatic cancer. Evaluation of pancreatic tumors following treatment with an experimental vaccine (Lutz et al. Cancer Immunology Research 2014) suggests that vaccination primes the tumor microenvironment (TME) for checkpoint-inhibitor immunotherapy, and supports a new platform for evaluating checkpoint-inhibitors in poorly immunogenic cancers.

TPS4160 Background: Combinatorial strategies aimed at priming tumor antigen-specific T cells while simultaneously blocking negative immune checkpoints may improve immunotherapy for immune tolerant ...

211 Background: Ipilimumab (IPI) at 3mg/kg has been tested in pancreatic ductal adenocarcinoma (PDA) with a low but detectable response rate. This supports a role for immunotherapy in PDA. Melanoma (MEL) studies demonstrate a dose-response relationship with IPI. Preclinical studies show synergy between anti-CTLA-4 antibodies and GM-CSF cell-based vaccines. This study evaluated IPI 10mg/kg alone (Arm 1) versus IPI 10mg/kg + vaccine (Arm 2) in PDA. Methods: 30 subjects with previously treated, locally advanced or metastatic PDA were randomized (1:1) to Arm 1 or 2. Induction treatments were administered every 3 weeks (wk) X 4 doses. Subjects with stable disease (SD) or better between wk 14 and 22 were eligible for maintenance doses every 12 wks. Activity was assessed by response and overall survival (OS). IFN-g Elispots and ELISAs were used to detect induction of mesothelin-specific T cells and galectin-3 antibodies (Abs), respectively. Results: Baseline characteristics were similar (87% metastatic, 100% gemcitabine-treated) with the exception that Arm 1 had a lower % of subjects with > 1 prior therapies (60 vs 100%). Arm 1 had 2 SD (7 and 22 wks). Arm 2 had 3 SD (1 delayed regression starting at wk 14 and maintained until wk 31, 1 delayed stabilization starting at wk 22 and ongoing at wk 57, 1 SD ongoing at wk 64). Transient CA19-9 declines were seen only in Arm 2 (7/15). Median OS was 3.3 vs 5.5 months in Arm 1 vs Arm 2 (p=0.12) with a 12 month OS of 7 vs 27%. 73% (Arm 1) and 80% (Arm 2) of subjects experienced immune related adverse events (IRAE). 20% of subjects on both arms had Grade 3-4 IRAEs including rash (1), colitis (2), Guillain-Barre (1), nephritis (1), and pneumonitis (1). Rash was less frequent in Arm 1 (53 vs 73%). IRAEs (p=0.037), mesothelin T cell responses (p=0.012), and enhancement of the T cell repertoire (p=0.026) were associated with OS in both arms. Galectin-3 Ab responses were associated with OS in Arm 2 (p=0.002). Conclusions: Immunotherapy has potential even in advanced PDA. IRAEs in PDA are similar to IRAEs in MEL. Delayed responses suggest that standard RECIST criteria will underestimate activity and targeting a population with a longer life expectancy may improve efficacy.

3010 Background: Pancreatic cancer remains the fourth leading cause of cancer related deaths in the US in 2006. Surgical resection provides the only possibility of cure. A standard adjuvant treatment approach for patients with resected disease has not yet been determined. We have developed an irradiated GM-CSF transfected allogeneic whole cell line pancreas adenocarcinoma vaccine. We have previously reported a follow-up 60 patient study in this same population using the highest bioactive vaccine dose identified in the initial phase I study. Methods: Single institution phase II study of 60 patients with resected pancreatic adenocarcinoma administered a total of 5 vaccines using two pancreatic cancer cell lines each delivering 2.5 X 10 8 cells ID. Vaccine one was administered 8–10 weeks following surgical resection. Patients subsequently were treated with 5-FU CI based chemotherapy integrated with radiotherapy. Patients who were disease-free one month after completion of chemoradiotherapy received vaccines 2–4, each 1 month apart. A fifth and final booster vaccine was administered 6 months after vaccine 4. The objectives of the study were: 1. To estimate overall survival and disease-free survival in patients with minimal residual disease treated with adjuvant chemoradiotherapy in sequence with the irradiated allogeneic GM-CSF transfected pancreatic tumor cell lines. 2. To characterize toxicities associated with intradermal injections of the vaccine. Results/Conclusions: The study completed enrollment of new patients in January 2005. Median follow-up for these patients is approximately 36 months. 1) The administration of a GM-CSF allogeneic pancreas cancer vaccine is safe and well tolerated; 2) The median survival is approximately 26 months. These results compare favorably with published data for resected pancreas cancer; 3) A matched cohort analysis comparing patients enrolled on this adjuvant vaccine study to the Johns Hopkins Surgery database of patients receiving surgery followed by chemoradiotherapy alone will be presented at this meeting; 4) Immune correlates will be presented at this meeting. No significant financial relationships to disclose.