Pancreatic cancer has one of the worst prognoses of any human malignancy and leukocyte infiltration is a major prognostic marker of the disease. As current immunotherapies confer negligible survival benefits, there is a need to better characterise leukocytes in pancreatic cancer to identify better therapeutic strategies. In this study, we analysed 32 human pancreatic cancer patients from two independent cohorts. A multi-parameter mass-cytometry analysis was performed on 32,000 T-cells from eight patients. Single-cell RNA sequencing dataset analysis was performed on a cohort of 24 patients. Multiplex immunohistochemistry imaging and spatial analysis were performed to map immune infiltration into the tumour microenvironment. Regulatory T-cell populations demonstrated highly immunosuppressive states with high TIGIT, ICOS and CD39 expression. CD8+ T-cells were found to be either in senescence or an exhausted state. The exhausted CD8 T-cells had low PD-1 expression but high TIGIT and CD39 expression. These findings were corroborated in an independent pancreatic cancer single-cell RNA dataset. These data suggest that T-cells are major players in the suppressive microenvironment of pancreatic cancer. Our work identifies multiple novel therapeutic targets that should form the basis for rational design of a new generation of clinical trials in pancreatic ductal adenocarcinoma.

Pure rhabdomyosarcomas occurring in the adult uterus are very rare, with poor prognosis. We present a case of a 67-year-old woman with postmenopausal vaginal bleeding caused by pleomorphic rhabdomyosarcoma of the uterus, treated with hysterectomy, bilateral salpingo-oophorectomy, pelvic/paraaortic lymphadenectomy and partial sigmoidectomy. Postoperative chemotherapy (Doxorubicin) was given according to protocol. Follow-up examinations one year after surgery revealed no abnormalities or tumor recurrence. The rarity of this histological entity makes the presented case worthy of publication.

Pancreatic cancer has the worst prognosis of any human malignancy and lymphocytes appear to be a major prognostic marker of the disease. There is a need to better characterise T-cells of pancreatic cancer in order to identify novel therapeutic strategies. In this study, a multi-parameter analysis of human pancreatic cancer cases revealed three novel characteristics of T-cells. Using a T-cell focused CyTOF panel, we analysed approximately 32,000 T-cells in eight patients. Our observations show a regulatory T-cell population was characterized by a highly immunosuppressive state with high TIGIT and ICOS expression, and the CD8 T-cells were either senescent or exhausted but with lower PD1 levels. These data suggest that the microenvironment of pancreatic cancer is extremely suppressive and could be a major driver of poor prognosis. These findings have been subsequently validated in a large pancreatic cancer single-cell RNA sequencing dataset using 13,000 T cells. This work identifies potential therapeutic targets and avenues that should be further investigated through rational design of clinical trials.

Background. Ciliated hepatic foregut cysts (CHFCs) are uncommon cystic lesions within the liver. CHFCs can undergo a malignant transformation to form a primary squamous cell carcinoma of the liver. The true incidence and natural history of CHFCs is unknown and the risk of malignant transformation is unclear. We present a single centre's experience of CFHC management. Methods. A retrospective review of a departmental database identified all patients with CHFCs over a 4 year time period. Patients with CHFCs confirmed on histological assessment or suspected on radiological imaging were included in this study. Clinical information regarding patient demographics, symptomatic presentation, surgical management and histopathological features were noted. The radiological characteristics of CHFCs were recorded and the malignant transformation rate was calculated. Results. 15 patients with CHFC were identified (7 histologically confirmed and 8 radiologically suspected cases). All patients were asymptomatic and the CHFCs were incidental findings. No CHFC developed an interval change in cyst features or underwent a malignant transformation during follow up. MRI serves as the most sensitive modality to diagnose CHFC. Conclusions. CHFCs may be more prevalent than previously reported. Definitive management should encompass a patient centred discussion regarding the merits of long term follow up with serial imaging versus resection on an individual basis once CHFC is diagnosed.

Background: Pancreatic cancer has the worst prognosis of any human malignancy. We have shown using transcriptomics and histopathology that immune infiltrate in resection samples from a Whipple’s operation is predictive of prognosis. In particular, lymphocytes appear to be a major prognostic marker. With promising immunotherapies being proposed for other cancers, there is a need for a deeper understanding of the immune landscape of pancreatic cancer to identify points of intervention. Methods: We have developed a 37-marker mass cytometry staining panel to characterize the dominant immune populations within primary pancreatic cancer. Our panel further analyzes T-cell subpopulations and their functional status, including a host of clinically relevant checkpoint markers and immunosuppressive signatures. Results: The degree of immune infiltration we observe is highly variable between patients, but all patients equivocally show a complex immune microenvironment consistent of macrophages, neutrophils, and different lymphocytes. The T cells infiltrating the tumor, both CD4 and CD8 T cells, appear to be dysfunctional with hardly any activation signature. A highly suppressive phenotype also characterizes the regulatory T-cell population. Our data suggest that the microenvironment of pancreatic cancer is extremely suppressive and could be a major driver of poor prognosis. Yet, this work identifies potential therapeutic targets and avenues that should be further investigated and may inspire future clinical trials. Future Work: We are planning to investigate the behavior of T-regs from PDAC using in vitro assays. To that end, we will use a recently developed advanced 3D culture system to visualize their interactions with CD8s and the functional consequences of those interactions on CD8-mediated killing. Citation Format: Shivan Sivakumar, Enas Abu-Shah, David Ahern, Nagina Mangal, Srikanth Reddy, Aniko Rendek, Zahir Soonawalla, Michael Silva, Mark Middleton, Michael L. Dustin. T-cell regulation in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A91.