Distinctive Pathology Associated With Focal Stenosis of the Main Pancreatic Duct Secondary to Remote Trauma: A Long-term Complication of Seat Belt Pancreatitis

The radiologic finding of focal stenosis of the main pancreatic duct is highly suggestive of pancreatic cancer. Even in the absence of a mass lesion, focal duct stenosis can lead to surgical resection of the affected portion of the pancreas. We present four patients with distinctive pathology associated with non-neoplastic focal stenosis of the main pancreatic duct. The pathology included stenosis of the pancreatic duct accompanied by wavy, acellular, serpentine-like fibrosis, chronic inflammation with foreign body-type giant cell reaction, and calcifications. In all cases, the pancreas toward the tail of the gland had obstructive changes including acinar drop-out and interlobular and intralobular fibrosis. Three of the four patients had a remote history of major motor vehicle accidents associated with severe abdominal trauma. These results emphasize that blunt trauma can injure the pancreas and that this injury can result in long-term complications, including focal stenosis of the main pancreatic duct. Pathologists should be aware of the distinct pathology associated with remote trauma and, when the pathology is present, should elicit the appropriate clinical history.

Pancreatoblastoma in an elderly woman: A case report simulating a pancreatic neuroendocrine tumour with emphasis on cytomorphological features

Pancreatoblastoma (PB), a rare malignant epithelial neoplasm, is the most common pancreatic neoplasm of childhood. It is exceptionally rare in the adult population and its occurrence is limited to case reports. Although the neoplastic cells of PB can have a number of different directions of differentiation, PB is defined by the combination of neoplastic cells with acinar differentiation and squamoid morules. We report a case of a female patient in her 70s who presented with elevated creatinine level, concerning a kidney disorder, and was found to have an abdominal mass on CT scan. Fine needle aspiration (FNA) showed cellular smears with numerous 3-dimentional clusters of acinar cells and scattered squamoid morules. A cell block showed sheets of cells, some of which formed acini. Numerous squamoid morules were noted and were highlighted by nuclear labelling with antibodies to B-catenin in the cell block. The FNA diagnosis was rendered as "carcinoma with acinar differentiation, favour pancreatoblastoma." Subsequent histological findings confirmed the PB diagnosis. Next generation sequencing detected a CTNNB1 mutation. Given the wide usage of FNA in the preoperative diagnosis of pancreatic masses, the cytopathologist needs to be aware of the morphological features of PB and its cytological differential diagnosis, even in an elderly patient. The differential diagnosis includes acinar cell carcinoma, pancreatic neuroendocrine tumour, and solid pseudopapillary neoplasm. In conclusion, the cytological finding of neoplastic cells with acinar differentiation combined with squamous morules and/or mesenchymal elements in the smears and more commonly in the cell blocks appears to be the most specific finding for the diagnosis of PB.

Acute appendicitis severity during the early COVID-19 pandemic period

Background

The early COVID-19 pandemic period significantly strained the US healthcare system. During this period, consultations and admissions for acute medical conditions decreased, which was associated with an increase in disease-specific morbidity and mortality. Therefore, we sought to determine what, if any, effect the early COVID-19 pandemic period had on the presentation, management, and histopathologic severity of acute appendicitis.

Methods

We performed a retrospective, observational study to compare the frequencies with which patients presented with acute appendicitis, the proportion of whom were managed surgically, and the distribution of histopathologic disease severity among all resected appendix specimens during the early COVID-19 pandemic period (March 6-June 30, 2020) to equivalent time periods for the 3 preceding/pre-pandemic years (2017-2019).

Results

Compared with equivalent pre-pandemic time periods, during the COVID-19 pandemic period there was no significant difference in the number of patients who presented for acute appendicitis, there was a decreased rate of surgical management (81% vs 94%; p=0.014), and there was an overall increase in the incidence of perforated appendicitis (31% vs 16%; p=0.004), including by histopathologic diagnosis (25% vs 11%; p=0.01).

Discussion

Despite potential patient hesitancy to present for care, the early COVID-19 pandemic period was associated with no significant change in the number of patients presenting with acute appendicitis; however, there was a significant increase in the incidence of perforated appendicitis. This study highlights the need to encourage patients to avoid late presentation for acute surgical conditions and for the robust planning for the medical management of otherwise surgical abnormalities during episodes of restricted or limited resources.

Level of evidence

Level III.

Protein detection in blood with single-molecule imaging

The ability to characterize individual biomarker protein molecules in patient blood samples could enable diagnosis of diseases at an earlier stage, when treatment is typically more effective. Single-molecule imaging offers a promising approach to accomplish this goal. However, thus far, single-molecule imaging methods have not been translated into the clinical setting. The detection limit of these methods has been confined to the picomolar (10^-12 M) range, several orders of magnitude higher than the circulating concentrations of biomarker proteins present in many diseases. Here, we describe single-molecule augmented capture (SMAC), a single-molecule imaging technique to quantify and characterize individual protein molecules of interest down to the subfemtomolar (<10^-15 M) range. We demonstrate SMAC in a variety of applications with human blood samples, including the analysis of disease-associated secreted proteins, membrane proteins, and rare intracellular proteins. SMAC opens the door to the application of single-molecule imaging in noninvasive disease profiling.

Abstract PR-004: Systemic and intratumoral immune profiling in metastatic pancreatic cancer patients who received front-line FOLFIRINOX and were treated with combination immunotherapy with CTLA-4 blockade in the maintenance setting

Background: Metastatic pancreatic ductal adenocarcinoma (PDA) has a dismal prognosis with a 5-year survival rate of 10%. For patients with metastatic PDA who respond to but cannot tolerate multi-agent chemotherapy, such as FOLFIRINOX, beyond 4-6 months, the optimal approach is unknown. Few studies have evaluated immunotherapy in the maintenance setting for PDA. Previously, a phase 2 trial in advanced PDA showed the promise of a GM-CSF-secreting allogeneic pancreatic tumor cell-based vaccine (GVAX) with CTLA-4 inhibitor, ipilimumab (IPI) [1]. Here we describe the first clinical testing of GVAX + IPI in the maintenance setting for patients with metastatic PDA who had ongoing response or stable disease after front-line FOLFIRINOX and evaluation of immune cell changes within the peripheral blood and tumor. Methods: From 40 vaccinated patients, we obtained paired peripheral blood lymphocytes (PBLs) from 20 patients and metastatic PDA biopsies from 6 of these 20 patients at baseline and week 7 (after at least two doses of GVAX + IPI). Samples were stratified into “stable” or “progressive” cohorts based on disease status on first restaging scan. To profile peripheral immune responses to treatment, we performed mass cytometry (CyTOF) analysis using a T cell-focused panel on PBLs. To profile intratumoral immune responses, biopsies containing &gt;30% tumor cellularity were chosen for 10-plex multiplex immunohistochemistry with T cell and myeloid cell-focused panels allowing us to examine changes in immune cell subsets after GVAX + IPI. Results. GVAX + IPI led to noticeable changes in PBLs including increases in T helper and cytotoxic effector memory cells and decrease in naïve cytotoxic T cells, regardless of disease status. Among co-inhibitory markers assayed on PBLs, GVAX + IPI upregulated TIM3 and PD-1 in most helper and cytotoxic T cells, while CTLA-4 was largely maintained. Interrogation of the metastatic tumor microenvironment at baseline and on-treatment revealed significant increases in CD8+ T cells and pro-inflammatory M1 macrophages and decrease in pro-tumor M2 macrophages. Based on the CD8+ T cell functional status, there were increases in late effector (EOMES-PD-1+) and memory (EOMES-PD-1-) CD8+ T cells in the metastatic tumor after immunotherapy. Conclusions: In summary, we have proposed a mechanism for our immunotherapy in the maintenance setting. GVAX may be inducing systemic and intratumoral activation of naïve T cells to antigen-specific T cells and promoting a decrease in immunosuppressive cells in the metastatic PDA microenvironment. Meanwhile, IPI may be blocking CTLA-4, which improves priming of T cells, but also may be leading to upregulation of regulatory markers TIM3 and PD-1 on T cell subsets as a compensatory mechanism. This trial highlights the challenge to inducing effective anti-tumor immune responses in metastatic PDA with inducible counterregulatory mechanisms. These compensatory increases could provide targets for the next generation of studies. 1Le DT, et al. J Immunother. 2013

Citation Format: Annie A. Wu, Katherine M. Bever, Won Jin Ho, Elana J. Fertig, Nan Niu, Lei Zheng, Rose M. Parkinson, Jennifer N. Durham, Beth Onners, Anna K. Ferguson, Cara Wilt, Andrew H. Ko, Andrea Wang-Gillam, Daniel A. Laheru, Robert A. Anders, Elizabeth D. Thompson, Elizabeth A. Sugar, Elizabeth M. Jaffee, Dung T. Le. Systemic and intratumoral immune profiling in metastatic pancreatic cancer patients who received front-line FOLFIRINOX and were treated with combination immunotherapy with CTLA-4 blockade in the maintenance setting [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PR-004.

Sex, age, and hospitalization drive antibody responses in a COVID-19 convalescent plasma donor population

Convalescent plasma is a leading treatment for coronavirus disease 2019 (COVID-19), but there is a paucity of data identifying its therapeutic efficacy. Among 126 potential convalescent plasma donors, the humoral immune response was evaluated using a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus neutralization assay with Vero-E6-TMPRSS2 cells; a commercial IgG and IgA ELISA to detect the spike (S) protein S1 domain (EUROIMMUN); IgA, IgG, and IgM indirect ELISAs to detect the full-length S protein or S receptor-binding domain (S-RBD); and an IgG avidity assay. We used multiple linear regression and predictive models to assess the correlations between antibody responses and demographic and clinical characteristics. IgG titers were greater than either IgM or IgA titers for S1, full-length S, and S-RBD in the overall population. Of the 126 plasma samples, 101 (80%) had detectable neutralizing antibody (nAb) titers. Using nAb titers as the reference, the IgG ELISAs confirmed 95%-98% of the nAb-positive samples, but 20%-32% of the nAb-negative samples were still IgG ELISA positive. Male sex, older age, and hospitalization for COVID-19 were associated with increased antibody responses across the serological assays. There was substantial heterogeneity in the antibody response among potential convalescent plasma donors, but sex, age, and hospitalization emerged as factors that can be used to identify individuals with a high likelihood of having strong antiviral antibody responses.

Evaluation of Cyclophosphamide/GVAX Pancreas Followed by Listeria-Mesothelin (CRS-207) with or without Nivolumab in Patients with Pancreatic Cancer

PURPOSE

Two studies in previously treated metastatic pancreatic cancer have been completed combining GVAX pancreas vaccine (GM-CSF-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and CRS-207 (live, attenuated Listeria monocytogenes-expressing mesothelin). In the current study, we compared Cy/GVAX followed by CRS-207 with (Arm A) or without nivolumab (Arm B).

PATIENTS AND METHODS

Patients with pancreatic adenocarcinoma who received one prior therapy for metastatic disease and RECIST measurable disease were randomized 1:1 to receive treatment on Arm A or Arm B. The primary objective was to compare overall survival (OS) between the arms. Additional objectives included assessment of progression-free survival, safety, tumor responses, CA19-9 responses, and immunologic correlates.

RESULTS

Ninety-three patients were treated (Arm A, 51; Arm B, 42). The median OS in Arms A and B were 5.9 [95% confidence interval (CI), 4.7-8.6] and 6.1 (95% CI, 3.5-7.0) months, respectively, with an HR of 0.86 (95% CI, 0.55-1.34). Objective responses were seen in 3 patients using immune-related response criteria (4%, 2/51, Arm A; 2%, 1/42, Arm B). The grade ≥3 related adverse event rate, whereas higher in Arm A (35.3% vs. 11.9%) was manageable. Changes in the microenvironment, including increase in CD8+ T cells and a decrease in CD68+ myeloid cells, were observed in long-term survivors in Arm A only.

CONCLUSIONS

Although the study did not meet its primary endpoint of improvement in OS of Arm A over Arm B, the OS was comparable with standard therapy. Objective responses and immunologic changes in the tumor microenvironment were evident.

A Phase II Study of Allogeneic GM-CSF-Transfected Pancreatic Tumor Vaccine (GVAX) with Ipilimumab as Maintenance Treatment for Metastatic Pancreatic Cancer

PURPOSE

This phase II study tested granulocyte-macrophage colony-stimulating factor (GM-CSF)-allogeneic pancreatic tumor cells (GVAX) and ipilimumab in metastatic pancreatic ductal adenocarcinoma (PDA) in the maintenance setting.

PATIENTS AND METHODS

Patients with PDA who were treated with front-line chemotherapy consisting of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) in the metastatic setting and had ongoing response or stable disease after 8-12 doses were eligible. Patients were randomized 1:1 to treatment with GVAX and ipilimumab given every 3 weeks for four doses then every 8 weeks (Arm A) or to FOLFIRINOX continuation (Arm B). The primary objective was to compare overall survival (OS) between the two arms.

RESULTS

Eighty-two patients were included in the final analysis (Arm A: 40; Arm B: 42). The study was stopped for futility after interim analysis. Median OS was 9.38 months [95% confidence interval (CI), 5.0-12.2] for Arm A and 14.7 months (95% CI, 11.6-20.0) for Arm B (HR, 1.75; P = 0.019). Using immune-related response criteria, two partial responses (5.7%) were observed in Arm A and four (13.8%) in Arm B. GVAX + ipilimumab promoted T-cell differentiation into effector memory phenotypes both in the periphery and in the tumor microenvironment and increased M1 macrophages in the tumor.

CONCLUSIONS

GVAX and ipilimumab maintenance therapy did not improve OS over continuation of chemotherapy and resulted in a numerically inferior survival in metastatic PDA. However, clinical responses and biological effects on immune cells were observed. Further study of novel combinations in the maintenance treatment of metastatic PDA is feasible.

How did we rapidly implement a convalescent plasma program?

Since the beginning of the COVID-19 pandemic, the use of convalescent plasma as a possible treatment has been explored. Here we describe our experience as the first U.S. organization creating a COVID-19 convalescent plasma program to support its use through the single-patient emergency investigational new drug, the National Expanded Access Program, and multiple randomized controlled trials. Within weeks, we were able to distribute more than 8000 products, scale up collections to more than 4000 units per week, meet hospital demand, and support randomized controlled trials to evaluate the efficacy of convalescent plasma treatment. This was through strategic planning; redeployment of staff; and active engagement of hospital, community, and public health partners. Our partners helped with donor recruitment, testing, patient advocacy, and patient availability. The program will continue to evolve as we learn more about optimizing the product. Remaining issues to be resolved are antibody titers, dose, and at what stage of disease to transfuse.

An exploratory study of metformin with or without rapamycin as maintenance therapy after induction chemotherapy in patients with metastatic pancreatic adenocarcinoma

Purpose: Metformin combined with the mTOR inhibitor rapamycin showed potential synergistic anti-tumor activity in preclinical studies in pancreatic ductal adenocarcinoma (PDA). This phase 1b study (NCT02048384) was conducted to evaluate the feasibility and activity of metformin +/– rapamycin in the maintenance setting for unselected patients with metastatic PDA (mPDA) treated with chemotherapy.

Materials and Methods: Eligible patients with stable or responding mPDA after ≥ 6 months on chemotherapy were randomized 1:1 to metformin alone (Arm A) or with rapamycin (Arm B), stratified by prior treatment with FOLFIRINOX. Fluorodeoxyglucose (FDG) PET scans and peripheral blood mononuclear cells were obtained for exploratory analyses.

Results: 22 subjects (11 per arm) received treatment per protocol. Median PFS/OS were 3.5 and 13.2 months respectively, with 2 year OS rate of 37%; there were no differences between arms. No responses were observed by RECIST; however, decreases in FDG avidity and/or CA19-9 were observed in several long-term survivors. Treatment related adverse events of Grade ≥ 3 occurred in 0% vs 27% of patients in Arm A vs B and were asymptomatic hematologic or electrolyte abnormalities that were not clinically significant. Improved survival was associated with low baseline neutrophil: lymphocyte ratio, baseline lack of assessable disease by PET, and greater expansion of dendritic cells following treatment.

Conclusions: Metformin +/– rapamycin maintenance for mPDA was well-tolerated and several patients achieved stable disease associated with exceptionally long survival. Further prospective studies are needed to clarify the role of these agents in the maintenance setting and to enhance patient selection for such approaches.

Abstract 4491: Association of intratumoral immunologic profile with overall survival in metastatic pancreatic cancer patients treated with combination immunotherapy with or without PD-1 blockade

Background: Metastatic pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis with a 5-year survival rate of 8%. Single-agent immunotherapies fail to show clinical activity due to a complex tumor microenvironment (TME) and lack of effector T cells. We previously showed in a neoadjuvant clinical trial that an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting, allogeneic PDAC vaccine (GVAX) recruited T cells into tumor and upregulated the PD-1/PD-L1 pathway1. Here we describe the first clinical testing of GVAX prime given with attenuated listeria monocytogenes expressing mesothelin (CRS-207) boost alone or in combination with nivolumab to block PD-1 signaling in metastatic PDAC patients, and evaluated changes in the TME.

Experimental Design: 22 metastatic PDAC biopsy pairs were obtained at baseline and after 2 GVAX prime and 1 CRS-207 boost from 96 vaccinated patients. Nivolumab was administered with each vaccine in patients randomized to vaccine + nivolumab arm. Biopsies containing &gt;30% tumor cellularity were chosen for multiplex immunohistochemistry (IHC) to examine changes in immune cell subtypes and their signaling pathways in tumors. We did a comparative analysis looking at lymphoid and myeloid complexity, immune function, and PD-L1 status of patients with overall survival (OS) &lt;150 days [short OS, n=6], 150-300 days [middle OS, n=11], and &gt;300 days [long OS, n=5] or by treatment arm.

Results: Favorable OS correlated with low CD68+ myeloid cell and high lymphoid cell numbers, which was detected after prime-boost. Evaluation of the functional status of CD8+ T cells after prime-boost of patients with long OS revealed a 10.2% increase in EOMES+PD1- effector memory and 1.4% decrease in EOMES+PD1+ exhausted T cells. At baseline, fewer CSF1R+ tumor associated macrophages (TAMs), CD68+CD163+ and CD163- myeloid cells in tumors was associated with long OS. We analyzed nivolumab’s effect on the TME and found that tumors from nivolumab-treated patients displayed a decrease in CD68+ myeloid cells after prime-boost compared to baseline. Interestingly, CD163+ TAMs in tumors of nivolumab-treated patients expressed higher PD-L1 levels.

Conclusion: This study suggests that induction of lymphoid-inflamed expression profiles with less exhausted and more effector memory CD8+ T cells during treatment is associated with long OS independent of nivolumab treatment. Fewer TAMs in pre-treatment biopsies and a low myeloid: lymphoid cell ratio in post-immunotherapy tumor samples may be predictive of improved survival. Our findings also suggest that nivolumab induces PD-L1 expression on myeloid cells. Continual identification of key tissue-based biomarkers that correlate with OS may be useful for predicting therapeutic response.

1) Lutz E. (2014) Cancer Immunol Res. Jul;2(7):616-31.

Citation Format: Annie A. Wu, Takahiro Tsujikawa, Gina Choe, Teresa Beechwood, Lisa M. Coussens, Jennifer N. Durham, Elizabeth M. Jaffee, Dung T. Le. Association of intratumoral immunologic profile with overall survival in metastatic pancreatic cancer patients treated with combination immunotherapy with or without PD-1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4491.

Current Status of Immunotherapies for Treating Pancreatic Cancer

PURPOSE OF REVIEW

Despite all efforts, pancreatic ductal adenocarcinoma (PDAC) remains a disease that causes substantial morbidity and mortality, with a 5-year survival rate of 7%. Innovative paradigms for treating PDAC are urgently needed.

RECENT FINDINGS

We discuss the advances and difficulties in using immunotherapy and developing immunotherapeutic vaccines for PDAC. Current excitement about antigen-specific immunotherapy has been propelled by advances in multiple areas, such as next-generation sequencing to identify neoantigens and manufacturing to produce immunotherapeutic vaccines. Antigen-specific immunotherapy is being actively explored in clinical trials. As the field of immunotherapy matures and as our understanding of the complex interactions between tumor and host develops, we hope to identify new methods for treating and managing PDAC.

Combining STING-based neoantigen-targeted vaccine with checkpoint modulators enhances antitumor immunity in murine pancreatic cancer

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.

Abstract 611: PD-1-based combination immunotherapy reinvigorates CD8+ T cells in metastatic pancreatic cancer patients with improved survival

Background: Metastatic pancreatic ductal adenocarcinoma (PDAC) is lethal with a 5-year survival rate of 2%. Single-agent immunotherapies fail to show clinical activity due to a complex tumor microenvironment (TME) and lack of effector T cells. We previously showed that an irradiated, granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting, allogeneic PDAC vaccine (GVAX) given as neoadjuvant recruited T cells into the tumor and upregulated the PD-1/PD-L1 pathway. Here we described the first testing of GVAX prime given with attenuated listeria monocytogenes expressing mesothelin (CRS-207) boost given with or without nivolumab to block PD-1 signaling and evaluated changes in the TME.

Experimental Design: Metastatic pancreatic tumor biopsies were obtained at baseline and after 2 GVAX prime and 1 CRS-207 boost from vaccinated patients. Nivolumab was administered with each vaccine in patients randomized to the nivolumab arm. Biopsies containing high density of tumor cells (&gt;30%) were chosen for multiplex immunohistochemistry (IHC) to examine changes in the immune cell subtypes and their signals in tumors. We did a comparative analysis looking at lymphoid, myeloid complexity, and immune functional status in the tumor microenvironment of patients who have overall survival &lt;6 months [short OS] and &gt;6 months [long OS].

Results: Post-immunotherapy changes in immune cell profiles correlated with overall survival. After prime-boost, expansion of CD8+ T cells was observed in the long OS group. Evaluation of the functional status of CD8+ T cells after prime-boost of short OS group showed an EOMES+PD1+ exhausted phenotype. In the myeloid compartment, low CSF1R+ tumor associated macrophages and CD68+ CD163+ and CD163- myeloid frequency in post-immunotherapy tumors were associated with less exhaustion of CD8+ T cells and long OS. The clinical trial is ongoing and blinded to study arm; thus, we have not yet analyzed whether nivolumab influences results. These data will be available at the time of abstract presentation.

Conclusion: This study provides evidence that longitudinal changes in immune cell complexity profiles can be correlated with overall survival. Increases in CD8+ early effectors and decreases in monocytes in baseline versus post-immunotherapy tumors are associated with improved survival. The exhausted CD8+ T cell profile in short OS patients may predict early responders versus nonresponders to vaccine containing immunotherapy.

Citation Format: Annie A. Wu, Takahiro Tsujikawa, Gina Choe, Teresa Beechwood, Lisa M. Coussens, Jennifer N. Durham, Elizabeth M. Jaffee, Dung T. Le. PD-1-based combination immunotherapy reinvigorates CD8+ T cells in metastatic pancreatic cancer patients with improved survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 611.

Heterogeneous Stromal Signaling within the Tumor Microenvironment Controls the Metastasis of Pancreatic Cancer

Understanding how stromal signals regulate the development of pancreatic ductal adenocarcinoma (PDAC) may suggest novel therapeutic interventions in this disease. In this study, we assessed the metastatic role of stromal signals suggested to be important in the PDAC microenvironment. Src and IGF-1R phosphorylated the prometastatic molecule Annexin A2 (AnxA2) at Y23 and Y333 in response to stromal signals HGF and IGF-1, respectively, and IGF-1 expression was regulated by the Sonic Hedgehog (Shh) pathway. Both Shh and HGF were heterogeneously expressed in PDAC stroma, and only dual inhibition of these pathways could significantly suppress AnxA2 phosphorylation, PDAC growth, and metastasis. Taken together, our results illuminate tumor-stromal interactions, which drive metastasis, and provide a mechanism-based rationale for a stroma-directed therapy for PDAC. Cancer Res; 77(1); 41-52. ©2016 AACR.

Semaphorin 3D autocrine signaling mediates the metastatic role of annexin A2 in pancreatic cancer

Most patients with pancreatic ductal adenocarcinoma (PDA) present with metastatic disease at the time of diagnosis or will recur with metastases after surgical treatment. Semaphorin-plexin signaling mediates the migration of neuronal axons during development and of blood vessels during angiogenesis. The expression of the gene encoding semaphorin 3D (Sema3D) is increased in PDA tumors, and the presence of antibodies against the pleiotropic protein annexin A2 (AnxA2) in the sera of some patients after surgical resection of PDA is associated with longer recurrence-free survival. By knocking out AnxA2 in a transgenic mouse model of PDA (KPC) that recapitulates the progression of human PDA from premalignancy to metastatic disease, we found that AnxA2 promoted metastases in vivo. The expression of AnxA2 promoted the secretion of Sema3D from PDA cells, which coimmunoprecipitated with the co-receptor plexin D1 (PlxnD1) on PDA cells. Mouse PDA cells in which SEMA3D was knocked down or ANXA2-null PDA cells exhibited decreased invasive and metastatic potential in culture and in mice. However, restoring Sema3D in AnxA2-null cells did not entirely rescue metastatic behavior in culture and in vivo, suggesting that AnxA2 mediates additional prometastatic mechanisms. Patients with primary PDA tumors that have abundant Sema3D have widely metastatic disease and decreased survival compared to patients with tumors that have relatively low Sema3D abundance. Thus, AnxA2 and Sema3D may be new therapeutic targets and prognostic markers of metastatic PDA.

Reprogramming the tumor microenvironment: tumor-induced immunosuppressive factors paralyze T cells

It has become evident that tumor-induced immuno-suppressive factors in the tumor microenvironment play a major role in suppressing normal functions of effector T cells. These factors serve as hurdles that limit the therapeutic potential of cancer immunotherapies. This review focuses on illustrating the molecular mechanisms of immunosuppression in the tumor microenvironment, including evasion of T-cell recognition, interference with T-cell trafficking, metabolism, and functions, induction of resistance to T-cell killing, and apoptosis of T cells. A better understanding of these mechanisms may help in the development of strategies to enhance the effectiveness of cancer immunotherapies.

PD-1/PD-L1 blockade together with vaccine therapy facilitates effector T-cell infiltration into pancreatic tumors

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.

Immunotherapy converts nonimmunogenic pancreatic tumors into immunogenic foci of immune regulation

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

Immunotherapy for head and neck cancer

Head and neck cancer represents a challenging disease. Despite recent treatment advances, which have improved functional outcomes, the long-term survival of head and neck cancer patients has remained unchanged for the past 25 years. One of the goals of adjuvant cancer therapy is to eradicate local regional microscopic and micrometastatic disease with minimal toxicity to surrounding normal cells. In this respect, antigen-specific immunotherapy is an attractive therapeutic approach. With the advances in molecular genetics and fundamental immunology, antigen-specific immunotherapy is being actively explored using DNA, bacterial vector, viral vector, peptide, protein, dendritic cell, and tumor-cell based vaccines. Early phase clinical trials have demonstrated the safety and feasibility of these novel therapies and the emphasis is now shifting towards the development of strategies, which can increase the potency of these vaccines. As the field of immunotherapy matures and as our understanding of the complex interaction between tumor and host develops, we get closer to realizing the potential of immunotherapy as an adjunctive method to control head and neck cancer and improve long-term survival in this patient population.

Metaphit antagonizes phencyclidine-induced hypothermia in the rat

The acute administration of phencyclidine (PCP) causes hypothermia in the rat. Metaphit (1-[1-(3-isothiocyanatophenyl)cyclohexyl]-piperidine) is a derivative of PCP that has been shown to irreversibly acylate PCP receptors in vitro and in vivo and can antagonize the behavioral and electrophysiological effects of PCP in the rat. The purpose of the present study was to determine whether pretreatment with metaphit can block the hypothermic effects of PCP in the rat. Metaphit or PCP (1.0 mumol/rat) were injected into the lateral ventricles of rats, and 24 hr later the subjects were challenged with PCP (20.0 mg/kg s.c.). Pretreatment with metaphit blocked PCP-induced hypothermia; however, pretreatment with PCP did not affect the subsequent hypothermic response to PCP. These results indicate that the antagonism of PCP-induced hypothermia by metaphit was a specific effect and not due to PCP receptor desensitization.