Clinical Impact of Molecular Subtyping of Pancreatic Cancer

Pancreatic ductal adenocarcinoma is a highly lethal malignancy, which has now become the seventh most common cause of cancer death in the world, with the highest mortality rates in Europe and North America. In the past 30 years, there has been some progress in 5-year survival (rates increasing from 2.5 to 10%), but this is still extremely poor compared to all other common cancer types. Targeted therapies for advanced pancreatic cancer based on actionable mutations have been disappointing, with only 3–5% showing even a short clinical benefit. There is, however, a molecular diversity beyond mutations in genes responsible for producing classical canonical signaling pathways. Pancreatic cancer is almost unique in promoting an excess production of other components of the stroma, resulting in a complex tumor microenvironment that contributes to tumor development, progression, and response to treatment. Various transcriptional subtypes have also been described. Most notably, there is a strong alignment between the Classical/Pancreatic progenitor and Quasi-mesenchymal/Basal-like/Squamous subtype signatures of Moffit, Collinson, Bailey, Puleo, and Chan-Seng-Yue, which have potential clinical impact. Sequencing of epithelial cell populations enriched by laser capture microscopy combined with single-cell RNA sequencing has revealed the potential genomic evolution of pancreatic cancer as being a consequence of a gene expression continuum from mixed Basal-like and Classical cell populations within the same tumor, linked to allelic imbalances in mutant KRAS, with metastatic tumors being more copy number-unstable compared to primary tumors. The Basal-like subtype appears more chemoresistant with reduced survival compared to the Classical subtype. Chemotherapy and/or chemoradiation will also enrich the Basal-like subtype. Squamous/Basal-like programs facilitate immune infiltration compared with the Classical-like programs. The immune infiltrates associated with Basal and Classical type cells are distinct, potentially opening the door to differential strategies. Single-cell and spatial transcriptomics will now allow single cell profiling of tumor and resident immune cell populations that may further advance subtyping. Multiple clinical trials have been launched based on transcriptomic response signatures and molecular subtyping including COMPASS, Precision Promise, ESPAC6/7, PREDICT-PACA, and PASS1. We review several approaches to explore the clinical relevance of molecular profiling to provide optimal bench-to-beside translation with clinical impact.

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Results of conversion surgery after the triple combination chemotherapy of SOXIRI (S-1/oxaliplatin/irinotecan) in patients with unresectable pancreatic cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.4_suppl.366 ◽

2019 ◽

Vol 37 (4_suppl) ◽

pp. 366-366

Author(s):

Naoya Ikeda ◽

Takahiro Akahori ◽

Sohei Satoi ◽

Hiroaki Yanagimoto ◽

Minako Nagai ◽

...

Keyword(s):

Pancreatic Cancer ◽

Locally Advanced ◽

Advanced Pancreatic Cancer ◽

Clinical Impact ◽

Ductal Adenocarcinoma ◽

Unresectable Pancreatic Cancer ◽

Conversion Surgery ◽

Open Label ◽

Grade 3 ◽

Medical University

366 Background: Recent improvements in chemotherapy for initially unresectable pancreatic ductal adenocarcinoma (UPDAC) occasionally show remarkable antitumor effect and lead to conversion surgery (CS). However, the optimal indication and clinical impact of CS remains unknown. We have recently developed a new regimen consisted of biweekly S-1, oxaliplatin, and irinotecan (SOXIRI). In this regimen, we used S-1 in alternate-day administration instead of 5-FU, that can be more feasible than FOLFIRINOX. The aim of this study was to evaluate the clinical impact of CS after SOXILI treatment for initially UPDAC. Methods: We conducted an open-label, single-arm, phase II study that was carried out at Nara Medical University and Kansai Medical University in Japan. Patients with untreated metastatic and locally advanced PDAC were enrolled. They received 80 mg/m2 twice a day of S-1 for 2 weeks in alternate-day administration, 150 mg/m2 of irinotecan on day 1, and 85 mg/m2 of oxaliplatin on day 1 of a 2-week cycle. Results: The 35 enrolled patients received a median of six (range: 2-15) treatment cycles. The RR was 22.8%; median OS, 17.7 months; and median PFS, 7.4 months. Major grade 3 or 4 toxicity included neutropenia (54%), anemia (17%), febrile neutropenia (11%), anorexia (9%), diarrhea (9%), and nausea (9%). Twenty-three out of 35 patients of UR-PDAC were unresectable locally advanced pancreatic cancer (UR-LAPA). Seven out of 23 patients with UR-LAPA underwent CS. Distal pancreatectomy with celiac axis resection was performed in three patients, central pancreatectomy was performed in one patient. Pancreatoduodenectomy (PD) was performed in two patients, and PD with portal vein resection in one patient. Two out of seven patients had postoperative complications. One case had grade B pancreatic fistula, and the other case underwent cholecystectomy due to acute cholecystitis. The median OS in patients who received CS was 31.4 months. Conclusions: SOXIRI regimen has shown promising clinical efficacy with acceptable tolerability in patients with unresectable pancreatic cancer. Furthermore, it may be a potent first-line treatment when considering conversion surgery. Clinical trial information: UMIN000014339.

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Single-Cell Transcriptomics Reveals the Expression of Aging- and Senescence-Associated Genes in Distinct Cancer Cell Populations

Cells ◽

10.3390/cells10113126 ◽

2021 ◽

Vol 10 (11) ◽

pp. 3126

Author(s):

Dominik Saul ◽

Robyn Laura Kosinsky

Keyword(s):

Single Cell ◽

Myelogenous Leukemia ◽

Ductal Adenocarcinoma ◽

Cell Populations ◽

Rna Seq ◽

Healthy Control ◽

Transcriptional Changes ◽

The Relationship ◽

Senescence Associated Genes

The human aging process is associated with molecular changes and cellular degeneration, resulting in a significant increase in cancer incidence with age. Despite their potential correlation, the relationship between cancer- and ageing-related transcriptional changes is largely unknown. In this study, we aimed to analyze aging-associated transcriptional patterns in publicly available bulk mRNA-seq and single-cell RNA-seq (scRNA-seq) datasets for chronic myelogenous leukemia (CML), colorectal cancer (CRC), hepatocellular carcinoma (HCC), lung cancer (LC), and pancreatic ductal adenocarcinoma (PDAC). Indeed, we detected that various aging/senescence-induced genes (ASIGs) were upregulated in malignant diseases compared to healthy control samples. To elucidate the importance of ASIGs during cell development, pseudotime analyses were performed, which revealed a late enrichment of distinct cancer-specific ASIG signatures. Notably, we were able to demonstrate that all cancer entities analyzed in this study comprised cell populations expressing ASIGs. While only minor correlations were detected between ASIGs and transcriptome-wide changes in PDAC, a high proportion of ASIGs was induced in CML, CRC, HCC, and LC samples. These unique cellular subpopulations could serve as a basis for future studies on the role of aging and senescence in human malignancies.

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Prognostic impact of chemoradiation-related lymphopenia in patients with locally advanced pancreatic cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.3_suppl.439 ◽

2021 ◽

Vol 39 (3_suppl) ◽

pp. 439-439

Author(s):

Daniel W Kim ◽

Grace Lee ◽

Colin D. Weekes ◽

David P. Ryan ◽

Aparna Raj Parikh ◽

...

Keyword(s):

Pancreatic Cancer ◽

Cox Model ◽

Locally Advanced ◽

Advanced Pancreatic Cancer ◽

Pancreatic Head ◽

Locally Advanced Pancreatic Cancer ◽

Ductal Adenocarcinoma ◽

Prognostic Impact ◽

Entire Cohort ◽

Grade 3

439 Background: Chemoradiation (CRT) induced lymphopenia is common and associated with poorer survival in multiple solid malignancies. The objective of this study was to evaluate the prognostic impact of lymphopenia in patients with nonmetastatic, unresectable pancreatic ductal adenocarcinoma (PDAC) treated by neoadjuvant FOLFIRINOX (5-fluorouracil [5FU]/leucovorin/irinotecan/oxaliplatin) followed by CRT. We hypothesized that severe lymphopenia would correlate with worse survival. Methods: The inclusion criteria for this single-institution retrospective study were: 1) biopsy-proven diagnosis of unresectable PDAC, 2) absence of distant metastasis, 3) receipt of neoadjuvant FOLFIRINOX followed by CRT, and 4) absolute lymphocyte count (ALC) available prior to and two months after initiating CRT. In general, CRT consisted of 5FU or capecitabine and RT with 58.8 Gy over 28 fractions. Lymphopenia was graded according to CTCAE v5.0. The primary variable of interest was lymphopenia at two months, dichotomized by ALC of < 0.5/μl (Grade 3 lymphopenia). The primary endpoint was overall survival (OS). Cox modeling and Kaplan-Meier methods were used to perform survival analyses. Results: A total of 138 patients were identified. Median follow-up for the entire cohort was 16 months. Median age was 65. Fifty-six percent were female, 86% were Caucasian, and 97% had ECOG ≤1. Median tumor size was 3.8 cm. Tumor location was pancreatic head in 63%, body in 22%, tail in 8%, and neck in 7%. Median baseline ALC for the entire cohort was 1.5 k/ul. Two months after initiating CRT, 106 (77%) had severe (Grade 3 or worse) lymphopenia. While there were no significant differences in baseline patient or disease characteristics, patients with severe lymphopenia received higher doses of RT with longer duration of treatment compared to those without severe lymphopenia. On multivariable Cox model, severe lymphopenia at two months was significantly associated with increased hazards of death (HR = 4.00 [95% CI 2.03-7.89], p < 0.001). Greater number of neoadjuvant FOLFIRINOX cycles received prior to CRT was associated with lower hazards of death (HR = 0.84 [95% CI 0.77-0.92], p < 0.001). The 12-month OS was 73% vs. 90% in the cohort with vs. without severe lymphopenia, respectively (log-rank p < 0.001). Conclusions: Treatment-related lymphopenia is common and severe lymphopenia may be a prognostic marker of poorer survival in locally advanced pancreatic cancer. Closer observation in high-risk patients and minimization of RT dose and duration are potential approaches to mitigating CRT-related lymphopenia. Our findings also suggest an important role of the host immunity in pancreatic cancer outcomes, supporting the ongoing efforts of immunotherapy trials in pancreatic cancer.

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Adjuvant and Neoadjuvant Therapy for Pancreatic Adenocarcinoma

10.2310/7800.16076 ◽

2017 ◽

Author(s):

Gregory C Wilson ◽

Brent T Xia ◽

Syed A Ahmed

Keyword(s):

Pancreatic Cancer ◽

Adjuvant Therapy ◽

Neoadjuvant Therapy ◽

Pancreatic Adenocarcinoma ◽

Locally Advanced ◽

Neoadjuvant Treatment ◽

Advanced Pancreatic Cancer ◽

Treatment Strategies ◽

Ductal Adenocarcinoma ◽

Borderline Resectable

Despite decades of advancement and research into the multimodal care of pancreatic cancer, mortality after the diagnosis of pancreatic ductal adenocarcinoma remains grim. The role of adjuvant therapy following surgical resection has been well established in the literature. However, adjuvant therapy is imperfect, and outside of a clinical trial, there are high rates of omission or delayed initiation of therapy. Neoadjuvant treatment strategies continue to be explored in the management of resectable, borderline-resectable, and locally advanced unresectable pancreatic adenocarcinoma. With improved resection rates and the possibility for tumor downstaging, neoadjuvant therapy has become standard for patients with borderline-resectable and locally advanced unresectable tumors. Additional benefits of neoadjuvant therapy in the treatment of resectable tumors include improved completion rates of systemic therapy and R0 resection rates. Future clinical trials, including the use of novel treatment agents and combination treatment strategies in both neoadjuvant and adjuvant regimens, will add value to the treatment of pancreatic adenocarcinoma. Key words: adjuvant therapy, borderline-resectable pancreatic cancer, locally advanced pancreatic cancer, neoadjuvant therapy, pancreatic adenocarcinoma, resectable disease

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Conversion Surgery for Advanced Pancreatic Cancer

Journal of Clinical Medicine ◽

10.3390/jcm8111945 ◽

2019 ◽

Vol 8 (11) ◽

pp. 1945

Author(s):

Thomas Hank ◽

Oliver Strobel

Keyword(s):

Pancreatic Cancer ◽

Locally Advanced ◽

Palliative Therapy ◽

Advanced Pancreatic Cancer ◽

Treatment Strategies ◽

Ductal Adenocarcinoma ◽

Conversion Surgery ◽

Radiological Criteria ◽

Intention To Treat ◽

Conversion Rates

While primarily unresectable locally advanced pancreatic cancer (LAPC) used to be an indication for palliative therapy, a strategy of neoadjuvant therapy (NAT) and conversion surgery is being increasingly used after more effective chemotherapy regimens have become available for pancreatic ductal adenocarcinoma. While high-level evidence from prospective studies is still sparse, several large retrospective studies have recently reported their experience with NAT and conversion surgery for LAPC. This review aims to provide a current overview about different NAT regimens, conversion rates, survival outcomes and determinants of post-resection outcomes, as well as surgical strategies in the context of conversion surgery after NAT. FOLFIRINOX is the predominant regimen used and associated with the highest reported conversion rates. Conversion rates considerably vary between less than 5% and more than half of the study population with heterogeneous long-term outcomes, owing to a lack of intention-to-treat analyses in most studies and a high heterogeneity in resectability criteria, treatment strategies, and reporting among studies. Since radiological criteria of local resectability are no longer applicable after NAT, patients without progressive disease should undergo surgical exploration. Surgery after NAT has to be aimed at local radicality around the peripancreatic vessels and should be performed in expert centers. Future studies in this rapidly evolving field need to be prospective, analyze intention-to-treat populations, report stringent and objective inclusion criteria and criteria for resection. Innovative regimens for NAT in combination with a radical surgical approach hold high promise for patients with LAPC in the future.

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Single-cell transcriptome analysis of tumor and stromal compartments of pancreatic ductal adenocarcinoma primary tumors and metastatic lesions

Genome Medicine ◽

10.1186/s13073-020-00776-9 ◽

2020 ◽

Vol 12 (1) ◽

Author(s):

Wei Lin ◽

Pawan Noel ◽

Erkut H. Borazanci ◽

Jeeyun Lee ◽

Albert Amini ◽

...

Keyword(s):

Single Cell ◽

Tumor Cells ◽

Cell Types ◽

Ductal Adenocarcinoma ◽

Cellular Composition ◽

Primary Tumors ◽

Metastatic Lesions ◽

Tumor Tissues ◽

Cell Type Specific ◽

Different Cell Types

Abstract Background Solid tumors such as pancreatic ductal adenocarcinoma (PDAC) comprise not just tumor cells but also a microenvironment with which the tumor cells constantly interact. Detailed characterization of the cellular composition of the tumor microenvironment is critical to the understanding of the disease and treatment of the patient. Single-cell transcriptomics has been used to study the cellular composition of different solid tumor types including PDAC. However, almost all of those studies used primary tumor tissues. Methods In this study, we employed a single-cell RNA sequencing technology to profile the transcriptomes of individual cells from dissociated primary tumors or metastatic biopsies obtained from patients with PDAC. Unsupervised clustering analysis as well as a new supervised classification algorithm, SuperCT, was used to identify the different cell types within the tumor tissues. The expression signatures of the different cell types were then compared between primary tumors and metastatic biopsies. The expressions of the cell type-specific signature genes were also correlated with patient survival using public datasets. Results Our single-cell RNA sequencing analysis revealed distinct cell types in primary and metastatic PDAC tissues including tumor cells, endothelial cells, cancer-associated fibroblasts (CAFs), and immune cells. The cancer cells showed high inter-patient heterogeneity, whereas the stromal cells were more homogenous across patients. Immune infiltration varies significantly from patient to patient with majority of the immune cells being macrophages and exhausted lymphocytes. We found that the tumor cellular composition was an important factor in defining the PDAC subtypes. Furthermore, the expression levels of cell type-specific markers for EMT+ cancer cells, activated CAFs, and endothelial cells significantly associated with patient survival. Conclusions Taken together, our work identifies significant heterogeneity in cellular compositions of PDAC tumors and between primary tumors and metastatic lesions. Furthermore, the cellular composition was an important factor in defining PDAC subtypes and significantly correlated with patient outcome. These findings provide valuable insights on the PDAC microenvironment and could potentially inform the management of PDAC patients.

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Systematic Generation of Patient-Derived Tumor Models in Pancreatic Cancer

Cells ◽

10.3390/cells8020142 ◽

2019 ◽

Vol 8 (2) ◽

pp. 142 ◽

Cited By ~ 5

Author(s):

Karl Roland Ehrenberg ◽

Jianpeng Gao ◽

Felix Oppel ◽

Stephanie Frank ◽

Na Kang ◽

...

Keyword(s):

Pancreatic Cancer ◽

Clinical Decision Making ◽

Primary Cultures ◽

Ductal Adenocarcinoma ◽

In Vitro Cultivation ◽

Tumor Models ◽

Primary Tumors ◽

Immunodeficient Mice ◽

Resected Patient

In highly aggressive malignancies like pancreatic cancer (PC), patient-derived tumor models can serve as disease-relevant models to understand disease-related biology as well as to guide clinical decision-making. In this study, we describe a two-step protocol allowing systematic establishment of patient-derived primary cultures from PC patient tumors. Initial xenotransplantation of surgically resected patient tumors (n = 134) into immunodeficient mice allows for efficient in vivo expansion of vital tumor cells and successful tumor expansion in 38% of patient tumors (51/134). Expansion xenografts closely recapitulate the histoarchitecture of their matching patients’ primary tumors. Digestion of xenograft tumors and subsequent in vitro cultivation resulted in the successful generation of semi-adherent PC cultures of pure epithelial cell origin in 43.1% of the cases. The established primary cultures include diverse pathological types of PC: Pancreatic ductal adenocarcinoma (86.3%, 19/22), adenosquamous carcinoma (9.1%, 2/22) and ductal adenocarcinoma with oncocytic IPMN (4.5%, 1/22). We here provide a protocol to establish quality-controlled PC patient-derived primary cell cultures from heterogeneous PC patient tumors. In vitro preclinical models provide the basis for the identification and preclinical assessment of novel therapeutic opportunities targeting pancreatic cancer.

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FGFR4 Inhibitor BLU9931 Attenuates Pancreatic Cancer Cell Proliferation and Invasion While Inducing Senescence: Evidence for Senolytic Therapy Potential in Pancreatic Cancer

Cancers ◽

10.3390/cancers12102976 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2976

Author(s):

Norihiko Sasaki ◽

Fujiya Gomi ◽

Hisashi Yoshimura ◽

Masami Yamamoto ◽

Yoko Matsuda ◽

...

Keyword(s):

Pancreatic Cancer ◽

Growth Factor Receptor ◽

Ductal Adenocarcinoma ◽

Cancer Cell Proliferation ◽

Single Nucleotide ◽

Primary Tumors ◽

Cellular Processes ◽

Matrix Metalloproteinase 1 ◽

Advanced Stages ◽

Membrane Type

Fibroblast growth factor receptor 4 (FGFR4), one of four tyrosine kinase receptors for FGFs, is involved in diverse cellular processes. Activation of FGF19/FGFR4 signaling is closely associated with cancer development and progression. In this study, we examined the expression and roles of FGF19/FGFR4 signaling in human pancreatic ductal adenocarcinoma (PDAC). In human PDAC cases, FGFR4 expression positively correlated with larger primary tumors and more advanced stages. Among eight PDAC cell lines, FGFR4 was expressed at the highest levels in PK-1 cells, in which single-nucleotide polymorphism G388R in FGFR4 was detected. For inhibition of autocrine/paracrine FGF19/FGFR4 signaling, we used BLU9931, a highly selective FGFR4 inhibitor. Inhibition of signal transduction through ERK, AKT, and STAT3 pathways by BLU9931 reduced proliferation in FGF19/FGFR4 signaling-activated PDAC cells. By contrast, BLU9931 did not alter stemness features, including stemness marker expression, anticancer drug resistance, and sphere-forming ability. However, BLU9931 inhibited cell invasion, in part, by downregulating membrane-type matrix metalloproteinase-1 in FGF19/FGFR4 signaling-activated PDAC cells. Furthermore, downregulation of SIRT1 and SIRT6 by BLU9931 contributed to senescence induction, priming these cells for quercetin-induced death, a process termed senolysis. Thus, we propose that BLU9931 is a promising therapeutic agent in FGFR4-positive PDAC, especially when combined with senolysis (195/200).

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Sequential neoadjuvant chemotherpy with nab-paclitaxel plus gemcitabine and FOLFIRINOX in locally advanced pancreatic cancer (LAPC): A PILOT study.

Journal of Clinical Oncology ◽

10.1200/jco.2013.31.15_suppl.e15193 ◽

2013 ◽

Vol 31 (15_suppl) ◽

pp. e15193-e15193 ◽

Cited By ~ 2

Author(s):

Volker Kunzmann ◽

Ingo Hartlapp ◽

Michael Scheurlen ◽

Hermann Einsele ◽

Justus Mueller ◽

...

Keyword(s):

Pancreatic Cancer ◽

Pilot Study ◽

Neoadjuvant Chemotherapy ◽

Locally Advanced ◽

Advanced Pancreatic Cancer ◽

Sensory Neuropathy ◽

Disease Stage ◽

Ductal Adenocarcinoma ◽

Hematological Toxicity ◽

Highly Active

e15193 Background: Nab-Paclitaxel (nab-P) + Gemcitabin (G) and FOLFIRINOX have both shown promising activity in metastatic pancreatic cancer (mPC). Our group has developed sequential usage of both regimens in order to exploit the stromal depletion effects of nab-P and increase global efficacy of chemotherapy in the neoadjuvant setting of LAPC. Methods: This pilot study evaluated patients with cytological/histological confirmed diagnosis of locally advanced pancreatic ductal adenocarcinoma without evidence of metastatic disease (stage III). nab-P+G was administered for 2 cycles (nab-P 125 mg/m2, G 1000 mg/ 2; on days 1, 8, 15; every 28 days) followed by 2 cycles of FOLFIRINOX (as reported by Conroy et al., NEJM 2011). Results: We report the preliminary analysis of 8 pts treated in our institution. Patients characteristics were M/F: 5/3; median age 63 (46-79); PS 0/1: 6/2. 3 pts (37%) had a biliary stent before starting treatment. All pts received the planned 4 cycles of neoadjuvant chemotherapy without dose reductions. There were no treatment-related deaths and none of pts stopped treatment due to toxicity. Grade 3-4 toxicities were neutropenia (50 %), nausea (12%), diarrhea (12%) and thrombopenia (25%). Grade 2-3 sensory neuropathy occured in 25% of pts. Prior nab-P+G did not result in increased hematological or non-hematological toxicity of FOLFIRINOX. Among the 8 patients evaluable so far, 5 partial responses (63%) and 3 stable disease (37%) have been observed, resulting in a disease control rate of 100%. After sequential chemotherapy 3 pts (37%) underwent radical surgical resection. Of note, all resected patients pts showed regression of the tumor (Evans Regression Score 2-4) with 1 patient fullfilling the criteria of a complete pathological remission (pCR). 4 pts received concomitant chemo-radiotherapy and 1 pt underwent an explorative laparotomy with evidence of occult (micronodular) peritoneal metastasis. Conclusions: Sequential neoadjuvant chemotherapy with nab-P+G and FOLFIRINOX seems to be highly active with manageable toxicity profile and may allow to achieve pCR in LAPC. These results are encouraging to test this approach in a prospective phase II trial.

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Pancreatic cancer is marked by complement-high blood monocytes and tumor-associated macrophages

Life Science Alliance ◽

10.26508/lsa.202000935 ◽

2021 ◽

Vol 4 (6) ◽

pp. e202000935

Author(s):

Samantha B Kemp ◽

Nina G Steele ◽

Eileen S Carpenter ◽

Katelyn L Donahue ◽

Grace G Bushnell ◽

...

Keyword(s):

Single Cell ◽

Pancreatic Ductal Adenocarcinoma ◽

Rna Sequencing ◽

Gene Expression Signature ◽

Ductal Adenocarcinoma ◽

Specific Gene ◽

Sequencing Analysis ◽

Tumor Associated Macrophages ◽

Primary Tumors ◽

Single Cell Rna Sequencing

Pancreatic ductal adenocarcinoma (PDA) is accompanied by reprogramming of the local microenvironment, but changes at distal sites are poorly understood. We implanted biomaterial scaffolds, which act as an artificial premetastatic niche, into immunocompetent tumor-bearing and control mice, and identified a unique tumor-specific gene expression signature that includes high expression of C1qa, C1qb, Trem2, and Chil3. Single-cell RNA sequencing mapped these genes to two distinct macrophage populations in the scaffolds, one marked by elevated C1qa, C1qb, and Trem2, the other with high Chil3, Ly6c2 and Plac8. In mice, expression of these genes in the corresponding populations was elevated in tumor-associated macrophages compared with macrophages in the normal pancreas. We then analyzed single-cell RNA sequencing from patient samples, and determined expression of C1QA, C1QB, and TREM2 is elevated in human macrophages in primary tumors and liver metastases. Single-cell sequencing analysis of patient blood revealed a substantial enrichment of the same gene signature in monocytes. Taken together, our study identifies two distinct tumor-associated macrophage and monocyte populations that reflects systemic immune changes in pancreatic ductal adenocarcinoma patients.

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