The immune landscape of a tumor is highly connected to patient prognosis and response to treatment, but little is known about how natural killer (NK) cells predict overall survival (OS) among patients with solid tumors. We present the first meta-analysis on NK cell infiltration into solid tumors as a prognostic indicator for OS, considering cancer types independently, and together. Samples were collected from 1973 to 2016 with results published between 1989 and 2020. From 53 studies, we found that NK cell infiltration corresponds with decreased risk of death (HR=0.34, 95% CI: 0.26-0.46; p<0.0001). Among studies that investigated the prognostic potential of NK cells in specific regions of the tumor, intraepithelial infiltration was better predictive of OS than NK infiltration in the tumor-adjacent stroma. Generally, NK cell infiltration is lower in advanced-stage and lower-grade tumors; nevertheless, it remains prognostically beneficial. This meta-analysis highlights an important prognostic role of NK cells in solid tumors, but exposes that few studies have considered the contributions of NK cells. Toward NK cell-based immunotherapies, it will be important to understand the conditions under which NK cells can be effective agents of tumor control.

Genomic profiling of pancreatic cancer using small core biopsies has taken an increasingly prominent role in precision medicine. However, if not appropriately preserved, nucleic acids (NA) from pancreatic tissues are known to be susceptible to degradation due to high intrinsic levels of nucleases. PAXgene fixation (PreAnalytix, Switzerland) represents a novel formalin-free tissue preservation method. We sought to compare the NA and histomorphological preservation of pancreatic cancer tissues preserved with PAXgene-fixed paraffin-embedding (PFPE) and formalin-fixed paraffin-embedding (FFPE). Tissues from 19 patients were obtained prospectively from pancreaticoduodenectomy specimens and evaluated by four gastrointestinal pathologists. The extracted NA were quantified by Nanodrop and Qubit and assessed for quality by qPCR, targeted next-generation sequencing (NGS) assay, and RNA-sequencing. Our results demonstrated that, when assessed blindly for morphological quality, the four pathologists deemed the PFPE slides adequate for diagnostic purposes. PFPE tissues enable greater yields of less fragmented and more amplifiable DNA. PFPE tissues demonstrated significantly improved quality control (QC) metrics in a targeted NGS assay including Median Absolute Pair-wise Difference (MAPD) scores. Our results support the use of PAXgene fixative for the processing of specimens from pancreatic cancers with the potential benefits of improved yields for more amplifiable DNA in low-yield biopsy specimens and its ideal use for amplicon-based NGS assays.

Background: At diagnosis, ~80% of pancreatic ductal adenocarcinomas (PDAC) have metastasized. Relapse is thus common even among patients who undergo surgical resection, the only curative option. PDAC progresses rapidly, and existing immunotherapies have been ineffective. We hypothesized that natural killer (NK) cell immunotherapies could be effective against PDAC because they recognize conserved and heterogeneous features associated with cellular stress and transformation and can seek out metastases distal to the primary tumor site. Here, we aim to define the key features of NK cells as effective agents for PDAC immunotherapy. Methods: We used The Cancer Genome Atlas Program (TCGA) PDAC Firehose data and flow cytometry to predict and measure the most common activating or inhibitory ligands available on PDAC for NK cell activation. To ascertain how the tumor might alter expression of these ligands during treatment, inflammation or immune pressure, we measured expression of NK ligands at rest, or after exposure to immune cells or inflammation. To test and rank the functional importance of these dynamic ligands in the recognition, killing and control of PDAC we used co-culture, antibody-blocking and an NK-competent humanized mouse model. Results: Leveraging the known sequential acquisition of mutations as a surrogate for disease progression, we observed a progressive loss of transcript expression for activating NK cell ligands and chemoattractants. Exposure of PDAC to NK cells or interferon-γ, an inflammatory stimulus, drove dynamic changes in expression of both activating and inhibitory ligands. In vitro co-culture assays revealed a redundancy in the activating receptors engaged in NK:PDAC interactions, but that human leukocyte antigens (HLA)-killer immunoglobulin-like receptors (KIR) signaling dominantly interrupted anti-PDAC activity. In NK-competent humanized mice, adoptively transferred, unselected, unmodified NK cells slowed tumor growth in a dose-dependent manner, but NK cells selected to avoid HLA I-driven inhibition were the most competent effectors for PDAC control. Conclusions: Although there is redundancy among activating ligand:receptor pairs for recognizing PDAC tumors, interactions between KIR and HLA define the extent to which antitumor activity can proceed. During tumor progression and in response to immunotherapy, NK:tumor interactions drive upregulation of HLA I molecules. Thus, educated NK cells from HLA I-disparate donors may be the more effective allogeneic NK immunotherapy for PDAC.

Pancreatic cancer is a complex malignancy associated with poor prognosis and high symptom burden. Optimal patient care relies on the integration of various sectors in the healthcare field as well as innovation through research. The Canadian National Pancreas Conference (NPC) was co-organized and hosted by Craig’s Cause Pancreatic Cancer Society and The Royal College of Physicians and Surgeons in November 2023 in Montreal, Canada. The conference sought to bridge the gap between Canadian healthcare providers and researchers who share the common goal of improving the prognosis, quality of life, and survival for patients with pancreatic cancer. The accredited event featured discussion topics including diagnosis and screening, value-based and palliative care, pancreatic enzyme replacement therapy, cancer-reducing treatment, and an overview of the current management landscape. The present article reviews the NPC sessions and discusses the presented content with respect to the current literature.

High-grade serous carcinoma (HGSC) of the ovary remains the deadliest gynecologic cancer, with 5-year survival rates of less than 50%. Remission is usually achieved by surgical debulking and chemotherapy, but most (∼70%) of patients ultimately develop treatment-resistant disease. Infiltration of immune cells into the HGSC microenvironment, including natural killer (NK) cells, is associated with lengthened overall and progression-free survival, suggesting that immunosurveillance contributes to HGSC control. The mechanisms permitting or prohibiting anticancer activity are unclear, but if understood, they might shed light on opportunities for immunotherapy or precision medicine. We investigated the interactions between NK cells and adenosine, an immunosuppressive metabolite that concentrates in HGSC. Exposure of HGSC to adenosine induces upregulation of ligands associated with NK cell inhibition, including HLA-E. On NK cells, adenosine induces upregulation of the cognate inhibitory receptor for HLA-E, natural killer group 2A (NKG2A). The CD16low NK cell subset was most responsive to the HGSC cell line, OVCAR4, but also more likely to upregulate NKG2A and become inhibited after adenosine treatment. A single nucleotide polymorphism (SNP) in the gene for NKG2A (V5: rs2734440 C) encodes for higher NKG2A surface expression and a stronger inhibitory response to HLA-E-expressing targets. Here, we demonstrate that NK cell suppression in the context of adenosine is most profound in NK cells homozygous for the V5 variant. Our results reveal a novel link between metabolism and immunologic inhibition and highlight the KLRC1-V5 variant as a putative biomarker for response to anti-NKG2A therapy and/or susceptibility to adenosine-driven immunosuppression.

Background: Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers, and has limited options for treatment. Low immune infiltration, desmoplastic stroma, and poor tumour immunogenicity are all expected to contribute to PDAC’s rapid progression and limited response to existing immunotherapies. PDAC tumours are mosaics of different sub-tumour microenvironments, including some that do contain immune cells. We hypothesized that increasing frequency of lymphocyte:tumour interactions would correlate with lengthened survival for patients with PDAC. Methods: Using multiplex immunofluorescence, digital pathology, and computational analyses, we profiled the spatial distribution, co-localization, and neighbourhood architecture of immune cells in tumours from 73 patients with PDAC. Results: Higher densities of CD3+CD8– (CD4+) T cells were associated with improved five-year overall survival, particularly when enriched at the tumour-stroma boundary (i.e. peritumoural). CD3+CD8-T cells, CD8+ T cells (CD3+CD8+), and B cells (CD20+) frequently co-infiltrated and co-localized, forming distinct immune neighbourhoods indicative of organized adaptive immunity. We defined three common immune neighbourhoods within PDAC (1) Macrophage-dominant; (2) T cell dominant; and (3) Disorganized. With greater tumour and peri-tumoural area represented by the T cell dominant neighbourhood, overall survival was increased. The other neighbourhoods were not significantly associated with outcomes. Conclusion: Immune cells self-assemble in predictable patterns in PDAC. The presence of T cell dominant neighbourhoods, which we interpret as supporting ongoing immune activation, best predict lengthened survival. Spatially organized immune interactions may serve as prognostic indicators and inform future studies for immunotherapies in PDAC.