Circulating Tumor Cells Enumeration from the Portal Vein for Risk Stratification in Early Pancreatic Cancer Patients

Effects of the superior mesenteric artery approach versus the no-touch approach during pancreatoduodenectomy on the mobilization of circulating tumour cells and clusters in pancreatic cancer (CETUPANC): randomized clinical trial

BACKGROUND

Patients with pancreatic ductal adenocarcinoma present early postoperative systemic metastases, despite complete oncological resection. The aim of this study was to assess two pancreatoduodenectomy approaches with regard to intraoperative circulating tumour cells and cluster mobilization and their potential association with the development of distant metastasis.

METHODS

Patients with periampullary tumours who underwent open pancreatoduodenectomy were randomly allocated to either the no-touch approach or the superior mesenteric artery approach. A total of four intraoperative portal vein samples (at the beginning of the intervention, after portal vein disconnection from the tumour, after tumour resection, and before abdominal closure) were collected to measure circulating tumour cells and cluster numbers. Primary outcomes were the intraoperative number of circulating tumour cells and cluster mobilization. Further, their potential impact on 3-year distant metastasis disease-free survival and overall survival was assessed.

RESULTS

A total of 101 patients with periampullary tumours were randomized (51 in the superior mesenteric artery group and 50 in the no-touch group) and 63 patients with pancreatic ductal adenocarcinoma (34 in the superior mesenteric artery group and 29 in the no-touch group) were analysed. Circulating tumour cells and cluster mobilization were similar in both the no-touch group and the superior mesenteric artery group at all time points. There were no significant differences between surgical groups with regard to the median metastasis disease-free survival (12.4 (interquartile range 6.1-not reached) months in the superior mesenteric artery group and 18.1 (interquartile range 12.1-not reached) months in the no-touch group; P = 0.730). Patients with intraoperative cluster mobilization from the beginning to the end of surgery developed significantly more distant metastases within the first year after surgery (P = 0.023). Two intraoperative factors (the superior mesenteric artery approach (P = 0.025) and vein resection (P < 0.001)) were predictive factors for cluster mobilization.

CONCLUSION

Patients undergoing pancreatoduodenectomy using either the no-touch approach or the superior mesenteric artery approach had similar circulating tumour cells and cluster mobilization and similar overall survival and metastasis disease-free survival. A high intraoperative cluster dissemination during pancreatoduodenectomy was a predictive factor for early metastases in patients with pancreatic ductal adenocarcinoma.

REGISTRATION NUMBER

NCT03340844 (http://www.clinicaltrials.gov)-CETUPANC trial.

Evaluating the benefits of adjuvant chemotherapy in patients with pancreatic cancer undergoing radical pancreatectomy after neoadjuvant therapy-a systematic review and meta-analysis

Background

More and more patients with pancreatic cancer (PC) received neoadjuvant therapy (NAT) and then underwent radical pancreatectomy. However, the benefit of adjuvant chemotherapy (AC) for these patients is still controversial. This study is designed to determine the benefits of postoperative AC for patients with PC undergoing NAT and radical resection.

Methods

We conducted a comprehensive search of the PubMed, Embase, Web of Science, and Cochrane Library databases, covering the period from their inception until 10 September 2023. Our analysis focused on the assessment of overall survival (OS) and recurrence-free survival (RFS) through meta-analysis. The fixed-effects model and the random-effects model were used to process the data. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were employed to determine the necessary of administering AC for patients with PC who have undergone NAT and radical resection. We retrieved 3,063 search results, of which 3,048 were excluded because of duplication or after applying our inclusion and exclusion criteria.

Results

A total of 15 studies with 21,113 patients (7,794 patients in the AC group and 13,319 in the non-AC group) were included, all of which reported OS, and three studies reported disease-free survival (DFS)/tumor-specific survival (CSS)/RFS. The final results showed that AC significantly improved OS and DFS/CSS/RFS in patients with PC who underwent pancreatectomy after NAT [OS: HR = 0.80, 95% CI (0.75∼0.86), P < 0.00001, I2 = 48%; DFS/CSS/RFS: HR = 0.53, 95% CI (0.41~0.69), P < 0.00001, I2 = 0%]. Furthermore, we performed subgroup analyses and demonstrated that AC provided a significant survival benefit for patients with PC after NAT and resection regardless of the tumor size [<2-cm subgroup: HR = 0.72, 95% CI (0.5∼0.94), P = 0.01; ≥2-cm subgroup: HR = 0.79, 95% CI (0.65∼0.96), P = 0.02] and the margin status [R0 subgroup: HR = 0.83, 95% CI (0.77∼0.88), P < 0.00001; R2 subgroup: HR = 0.75, 95% CI (0.61∼0.92), P = 0.007]. AC also benefited the patients with a stage N0 [HR = 0.79, 95% CI (0.74~0.84), P < 0.00001], N1 [HR = 0.78, 95% CI (0.72∼0.85), P < 0.00001], or poorly/undifferentiated tumor [HR = 0.76, 95% CI (0.66∼0.87), P < 0.0001] in survival but not in patients with a stage N2 [HR = 0.69, 95% CI (0.43∼1.09), P = 0.11] or well/moderately differentiated tumor [HR = 0.97, 95% CI (0.66∼1.42), P = 0.87].

Conclusions

Although AC showed survival benefit for patients with PC undergoing radical pancreatectomy after NAT, we still need to consider the lymph node stage and the degree of differentiation of the tumor when we gave AC to a patient. High-quality prospective randomized controlled studies are required to well disclose the value of AC in patients with PC undergoing radical pancreatectomy after NAT.

Systematic review registration

https://www.crd.york.ac.uk/prospero/ PROSPERO, identifier CRD42023461365.

Circulating tumor cells in pancreatic cancer: more than liquid biopsy

Circulating tumor cells (CTCs) are tumor cells that slough off the primary lesions and extravasate into the bloodstream. By forming CTC clusters and interacting with other circulating cells (platelets, NK cells, macrophage, etc.), CTCs are able to survive in the circulatory system of tumor patients and colonize to metastatic organs. In recent years, the potential of CTCs in diagnosis, prognostic assessment, and individualized therapy of various types of tumors has been gradually explored, while advances in biotechnology have made it possible to extract CTCs from patient blood samples. These biological features of CTCs provide us with new insights into cancer vulnerabilities. With the advent of new immunotherapies and personalized medicines, disrupting the heterotypical interaction between CTCs and circulatory cells as well as direct CTCs targeting hold great promise. Pancreatic cancer (PC) is one of the most malignant cancers, in part because of early metastasis, difficult diagnosis, and limited treatment options. Although there is significant potential for CTCs as a biomarker to impact PC from diagnosis to therapy, there still remain a number of challenges to the routine implementation of CTCs in the clinical management of PC. In this review, we summed up the progress made in understanding biological characteristics and exceptional technological advances of CTCs and provided insight into exploiting these developments to design future clinical tools for improving the diagnosis and treatment of PC.

High-throughput enrichment of portal venous circulating tumor cells for highly sensitive diagnosis of CA19-9-negative pancreatic cancer patients using inertial microfluidics

The carbohydrate antigen 19-9 (CA19-9) is commonly used as a representative biomarker for pancreatic cancer (PC); however, it lacks sensitivity and specificity for early-stage PC diagnosis. Furthermore, some patients with PC are negative for CA19-9 (<37 U/mL), which introduces additional limitations to their accurate diagnosis and treatment. Hence, improved methods to accurately detect PC stages in CA19-9-negative patients are warranted. In this study, tumor-proximal liquid biopsy and inertial microfluidics were coupled to enable high-throughput enrichment of portal venous circulating tumor cells (CTCs) and support the effective diagnosis of patients with early-stage PC. The proposed inertial microfluidic system was shown to provide size-based enrichment of CTCs using inertial focusing and Dean flow effects in slanted spiral channels. Notably, portal venous blood samples were found to have twice the yield of CTCs (21.4 cells per 5 mL) compared with peripheral blood (10.9 CTCs per 5 mL). A combination of peripheral and portal CTC data along with CA19-9 results showed to greatly improve the average accuracy of CA19-9-negative PC patients from 47.1% with regular CA19-9 tests up to 87.1%. Hence, portal venous CTC-based microfluidic biopsy can be used with high sensitivity and specificity for the diagnosis of early-stage PC, particularly in CA19-9-negative patients.

Circulating tumor cells in pancreatic cancer: The prognostic impact in surgical patients

Pancreatic cancer is associated with a poor prognosis, even in the early stages, mainly due to metastatic progression. New diagnostic techniques that predict unfavorable outcomes are needed in order to improve treatment strategies. Circulating tumor cells (CTCs) are showing promising results as a predictive biomarker for various tumors. In this editorial we comment on the article by Zhang et al, who published the first systematic review and meta-analysis evaluating the prognostic value of CTCs as biomarkers in early-stage pancreatic cancer patients undergoing surgery. CTCs were detected in peripheral or central venous system blood, before or during surgery. Positive CTCs showed a correlation with decreased overall survival and decreased relapse-free, disease-free and progression-free survival in this meta-analysis. However, the heterogeneity was significant. The authors suggest that this result was related to the separation methods used between studies, but other differences such as the margin status or the neoadjuvant and adjuvant treatments used are also important to consider. CTCs may be a potential prognostic biomarker in pancreatic cancer patients, but it is necessary to compare and standardize the platforms used to isolate CTCs, to compare different biomarkers from liquid biopsy and to determine the impact on prognosis when therapeutic changes are made based on CTCs levels.

Layer-by-layer fabrication of alginate/polyethyleneimine multilayer on magnetic interface with enhanced efficiency in immuno-capturing circulating tumor cells

BACKGROUND

The technology of capturing circulating tumor cells (CTCs) plays a crucial role in the diagnosis, evaluation of therapeutic efficacy, and prediction of prognosis in lung cancer. However, the presence of complex blood environment often results in severe nonspecific protein adsorption and interferences from blood cells, which negatively impacts the specificity of CTCs capture. There is a great need for development of novel nanomaterials for CTCs capture with prominent anti-nonspecific adsorptions from proteins or blood cells.

RESULTS

We present a novel immune magnetic probe Fe3O4@(PEI/AA)4@Apt. The surface of Fe3O4 particles was modified with four layers of PEI/AA composite by layer-by-layer assembly. Furthermore, aptamers targeting epithelial marker EpCAM (SYL3C) and mesenchymal marker CSV (ZY5C) were simultaneously connected on Fe3O4@(PEI/AA)4 to improve the detection of different phenotypic CTCs and reduce false negatives. The results demonstrated that the (PEI/AA)4 coatings not only minimized non-specific protein adsorptions, but also significantly reduced the adsorption rate of red blood cells to a mere 1 %, as a result of which, the Fe3O4@(PEI/AA)4@Apt probe achieved a remarkably high capture efficiency toward CTCs (95.9 %). In the subsequent validation of clinical samples, the probe was also effective in capturing rare CTCs from lung cancer patients.

SIGNIFICANCE AND NOVELTY

A (PEI/AA) polymerized composite with controllable layers was fabricated by layer-by-layer self-assembly technique, which displayed remarkable anti-nonspecific adsorption capabilities toward proteins and cells. Importantly, Fe3O4@(PEI/AA)4@Apt probe significantly improved CTCs capture purity in lung cancer patients to 89.36 %. For the first time, this study combined controllable (PEI/AA) layers with magnetic separation to innovatively build a resistant interface that significantly improves the specific capture performances of CTCs, broadening the application of this polymerized composite.

Research progress on the multi-omics and survival status of circulating tumor cells

In the dynamic process of metastasis, circulating tumor cells (CTCs) emanate from the primary solid tumor and subsequently acquire the capacity to disengage from the basement membrane, facilitating their infiltration into the vascular system via the interstitial tissue. Given the pivotal role of CTCs in the intricate hematogenous metastasis, they have emerged as an essential resource for a deeper comprehension of cancer metastasis while also serving as a cornerstone for the development of new indicators for early cancer screening and new therapeutic targets. In the epoch of precision medicine, as CTC enrichment and separation technologies continually advance and reach full fruition, the domain of CTC research has transcended the mere straightforward detection and quantification. The rapid advancement of CTC analysis platforms has presented a compelling opportunity for in-depth exploration of CTCs within the bloodstream. Here, we provide an overview of the current status and research significance of multi-omics studies on CTCs, including genomics, transcriptomics, proteomics, and metabolomics. These studies have contributed to uncovering the unique heterogeneity of CTCs and identifying potential metastatic targets as well as specific recognition sites. We also review the impact of various states of CTCs in the bloodstream on their metastatic potential, such as clustered CTCs, interactions with other blood components, and the phenotypic states of CTCs after undergoing epithelial-mesenchymal transition (EMT). Within this context, we also discuss the therapeutic implications and potential of CTCs.

Circulating tumor cells as potential prognostic biomarkers for early-stage pancreatic cancer: A systematic review and meta-analysis

BACKGROUND

Pancreatic cancer is difficult to be diagnosed early clinically, while often leads to poor prognosis. If optimal personalized treatment plan can be provided to pancreatic cancer patient at an earlier stage, this can greatly improve overall survival (OS). Circulating tumor cells (CTCs) are a collective term for various types of tumor cells present in the peripheral blood (PB), which are formed by detachment during the development of solid tumor lesions. Most CTCs undergo apoptosis or are phagocytosed after entering the PB, whereas a few can escape and anchor at distal sites to develop metastasis, increasing the risk of death for patients with malignant tumors.

AIM

To investigate the significance of CTCs in predicting the prognosis of early pancreatic cancer patients.

METHODS

The PubMed, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine, and ChinaInfo databases were searched for articles published through December 2022. Studies were considered qualified if they included patients with early pancreatic cancer, analyzed the prognostic value of CTCs, and were full papers reported in English or Chinese. Researches were selected and assessed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol and the Newcastle-Ottawa Scale criteria. We used a funnel plot to assess publication bias.

RESULTS

From 1595 publications, we identified eight eligible studies that collectively enrolled 355 patients with pancreatic cancer. Among these original studies, two were carried out in China; three in the United States; and one each in Italy, Spain, and Norway. All eight studies analyzed the relevance between CTCs and the prognosis of patients with early-stage pancreatic cancer after surgery. A meta-analysis showed that the patients that were positive pre-treatment or post-treatment for CTCs were associated with decreased OS [hazard ratio (HR) = 1.93, 95% confidence interval (CI): 1.197-3.126, P = 0.007] and decreased relapse-free/disease-free/progression-free survival (HR = 1.27, 95%CI: 1.137-1.419, P < 0.001) in early-stage pancreatic cancer. Additionally, the results suggest no statistically noticeable publication bias for overall, disease-free, progression-free, and recurrence-free survival.

CONCLUSION

This pooled meta-analysis shows that CTCs, as biomarkers, can afford reliable prognostic information for patients with early-stage pancreatic cancer and help develop individualized treatment plans.

Preoperative treatments in borderline resectable and locally advanced pancreatic cancer: current evidence and new perspectives

Surgery is the only curative treatment for non-metastatic pancreatic adenocarcinoma, but less than 20% of patients present a resectable disease at diagnosis. Treatment strategies and disease definition for borderline resectable pancreatic cancer (BRPC) and locally advanced pancreatic cancer (LAPC) vary in the different cancer centres. Preoperative chemotherapy (CT) is the standard of care for both BRPC and LAPC patients, however literature data are still controversial concerning the type, dose and duration of the different CT regimens, as well as regarding the integration of radiotherapy (RT) or chemoradiation (CRT) in the therapeutic algorithm. In this unsettled debate, we aimed at focusing on the therapeutic regimens currently in use and relative literature data, to report international trials comparing the available therapeutic options or explore the introduction of new pharmacological agents, and to analyse possible new scenarios in microenvironment evaluation before and after neoadjuvant therapies or in patients' selection at a molecular level.

Clinical implications and perspectives of portal venous circulating tumor cells in pancreatic cancer

Despite recent improvements in the diagnosis and treatment of pancreatic cancer (PC), clinical outcomes remain dismal. Moreover, there are no effective prognostic or predictive biomarkers or options beyond carbohydrate antigen 19-9 for personalized and precise treatment. Circulating tumor cells (CTCs), as a member of the liquid biopsy family, could be a promising biomarker; however, the rarity of CTCs in peripheral venous blood limits their clinical use. Because the first venous drainage of PC is portal circulation, the portal vein can be a more suitable location for the detection of CTCs. Endoscopic ultrasound-guided portal venous sampling of CTCs is both feasible and safe. Several studies have suggested that the detection rate and number of CTCs may be higher in the portal blood than in the peripheral blood. CTC counts in the portal blood are highly associated with hepatic metastasis, recurrence after surgery, and survival. The phenotypic and genotypic properties measured in the captured portal CTCs can help us to understand tumor heterogeneity and predict the prognosis of PC. Small sample sizes and heterogeneous CTC detection methods limit the studies to date. Therefore, a large number of prospective studies are needed to corroborate portal CTCs as a valid biomarker in PC.

Successful resection of port site recurrence of pancreatic ductal adenocarcinoma after laparoscopic distal pancreatectomy

BACKGROUND

There are many reports of port site recurrence after laparoscopic surgery for various types of cancer. However, only two cases of port site recurrence after laparoscopic pancreatectomy have been reported to date. We herein report a case of port site recurrence after laparoscopic distal pancreatectomy.

CASE PRESENTATION

A 73-year-old woman was diagnosed with pancreatic tail cancer and underwent laparoscopic distal pancreatectomy with splenectomy. Histopathological examination revealed pancreatic ductal carcinoma (pT1N0M0 pStage I). The patient was discharged on postoperative day 14 with no complications. However, 5 months after surgery, computed tomography showed a small tumor at the right abdominal wall. No distant metastasis had appeared after 7 months of follow-up. Under the diagnosis of port site recurrence without any other metastases, we resected this abdominal tumor. Histopathological examination showed port site recurrence of pancreatic ductal carcinoma. No recurrence was observed 15 months postoperatively.

CONCLUSIONS

This is the report of successful resection of port site recurrence of pancreatic cancer.

Association of Adjuvant Chemotherapy in Patients With Resected Pancreatic Adenocarcinoma After Multiagent Neoadjuvant Chemotherapy

Importance

The total number of patients with pancreatic ductal adenocarcinoma (PDAC) who receive neoadjuvant chemotherapy (NAC) is increasing. However, the added role of adjuvant chemotherapy (AC) in these patients remains unknown.

Objective

To evaluate the association of AC with overall survival (OS) in patients with PDAC who received multiagent NAC followed by curative-intent surgery.

Design, Setting, and Participants

This retrospective, matched-cohort study used data from the National Cancer Database and included patients with PDAC diagnosed between 2010 and 2018. The study included patients at least 18 years of age who received multiagent NAC followed by surgical resection and had available records of the pathological findings. Patients were excluded if they had clinical or pathological stage IV disease or died within 90 days of their operation.

Exposures

All included patients received NAC and underwent resection for primary PDAC. Some patients received adjuvant chemotherapy.

Main Outcomes and Measures

The main outcome was the OS of patients who received AC (AC group) vs those who did not (non-AC group). Interactions between pathological findings and AC were investigated in separate multivariable Cox regression models.

Results

In total, 1132 patients (mean [SD] age, 63.5 [9.4] years; 577 [50.1%] male; 970 [85.7%] White) were included, 640 patients in the non-AC group and 492 patients in the AC group. After being matched by propensity score according to demographic and pathological characteristics, 444 patients remained in each group. The multivariable Cox regression model adjusted for all covariates revealed an association between AC and improved survival (hazard ratio, 0.71; 95% CI, 0.59-0.85; P < .001). Subgroup interaction analysis revealed that AC was significantly associated with better OS (26.6 vs 21.2 months; P = .002), but the benefit varied by age, pathological T category, and tumor differentiation. Of note, AC was associated with better survival in patients with any pathological N category and positive margin status.

Conclusions and Relevance

In this cohort study, AC following multiagent NAC and resection in patients with PDAC was associated with significant survival benefit compared with that in patients who did not receive AC. These findings suggest that patients with aggressive tumors may benefit from AC to achieve prolonged survival, even after multiagent NAC and curative-intent resection.

Quantification and Characterization of CTCs and Clusters in Pancreatic Cancer by Means of the Hough Transform Algorithm

Circulating Tumor Cells (CTCs) are considered a prognostic marker in pancreatic cancer. In this study we present a new approach for counting CTCs and CTC clusters in patients with pancreatic cancer using the Isoflux^TM System with the Hough transform algorithm (Hough-Isoflux^TM). The Hough-Isoflux^TM approach is based on the counting of an array of pixels with a nucleus and cytokeratin expression excluding the CD45 signal. Total CTCs including free and CTC clusters were evaluated in healthy donor samples mixed with pancreatic cancer cells (PCCs) and in samples from patients with pancreatic ductal adenocarcinoma (PDAC). The Isoflux^TM System with manual counting was used in a blinded manner by three technicians who used Manual-Isoflux^TM as a reference. The accuracy of the Hough-Isoflux^TM approach for detecting PCC based on counted events was 91.00% [84.50, 93.50] with a PCC recovery rate of 80.75 ± 16.41%. A high correlation between the Hough-Isoflux^TM and Manual-Isoflux^TM was observed for both free CTCs and for clusters in experimental PCC (R² = 0.993 and R² = 0.902 respectively). However, the correlation rate was better for free CTCs than for clusters in PDAC patient samples (R² = 0.974 and R² = 0.790 respectively). In conclusion, the Hough-Isoflux^TM approach showed high accuracy for the detection of circulating pancreatic cancer cells. A better correlation rate was observed between Hough-Isoflux^TM approach and with the Manual-Isoflux^TM for isolated CTCs than for clusters in PDAC patient samples.

TARTESSUS: A Customized Electrospun Drug Delivery System Loaded with Irinotecan for Local and Sustained Chemotherapy Release in Pancreatic Cancer

Post-surgical chemotherapy in pancreatic cancer has notorious side effects due to the high dose required. Multiple devices have been designed to tackle this aspect and achieve a delayed drug release. This study aimed to explore the controlled and sustained local delivery of a reduced drug dose from an irinotecan-loaded electrospun nanofiber membrane (named TARTESSUS) that can be placed on the patients' tissue after tumor resection surgery. The drug delivery system formulation was made of polycaprolactone (PCL). The mechanical properties and the release kinetics of the drug were adjusted by the electrospinning parameters and by the polymer ratio between 10 w.t.% and 14 w.t.% of PCL in formic acid:acetic acid:chloroform (47.5:47.5:5). The irinotecan release analysis was performed and three different release periods were obtained, depending on the concentration of the polymer in the dissolution. The TARTESSUS device was tested in 2D and 3D cell cultures and it demonstrated a decrease in cell viability in 2D culture between 72 h and day 7 from the start of treatment. In 3D culture, a decrease in viability was seen between 72 h, day 7 (p < 0.001), day 10 (p < 0.001), 14 (p < 0.001), and day 17 (p = 0.003) as well as a decrease in proliferation between 72 h and day 10 (p = 0.030) and a reduction in spheroid size during days 10 (p = 0.001), 14 (p < 0.001), and 17 (p < 0.001). In conclusion, TARTESSUS showed a successful encapsulation of a chemotherapeutic drug and a sustained and delayed release with an adjustable releasing period to optimize the therapeutic effect in pancreatic cancer treatment.

The Value of Circulating Tumor Cells in the Prognosis and Treatment of Pancreatic Cancer

In the past few decades, tumor diagnosis and treatment theory have developed in a variety of directions. The number of people dying from pancreatic cancer increases while the mortality rate of other common tumors decreases. Traditional imaging methods show the boundaries of pancreatic tumor, but they are not sufficient to judge early micrometastasis. Although carcinoembryonic antigen (CEA) and carbohydrate antigen19-9 (CA19-9) have the obvious advantages of simplicity and minimal invasiveness, these biomarkers obviously lack sensitivity and specificity. Circulating tumor cells (CTCs) have attracted attention as a non-invasive, dynamic, and real-time liquid biopsy technique for analyzing tumor characteristics. With the continuous development of new CTCs enrichment technologies, substantial progress has been made in the basic research of CTCs clinical application prospects. In many metastatic cancers, CTCs have been studied as an independent prognostic factor. This article reviews the research progress of CTCs in the treatment and prognosis of pancreatic cancer.

Pancreatic Ductal Adenocarcinoma (PDAC) circulating tumor cells influence myeloid cell differentiation to support their survival and immunoresistance in portal vein circulation

The portal venous circulation provides a conduit for pancreatic ductal adenocarcinoma (PDAC) tumor cells to the liver parenchyma sinusoids, a frequent site of metastasis. Turbulent flow in the portal circulation promotes retention of PDAC shed circulating tumor cells (CTC) and myeloid-derived immunosuppressor cells (MDSC). Excessive colony stimulating factor-1 receptor (CSF1R) signaling can induce myeloid differentiation to MDSC and transformation of MDSC to myeloid-derived fibroblasts (M-FB). Interactions between PDAC CTC and M-FB in the portal blood promotes the formation of immunoresistant clusters that enhance CTC proliferation, migration, and survival. Analysis of portal and peripheral blood samples collected intraoperatively from 30 PDAC patients undergoing pancreatico-duodenectomy showed that PDAC patient plasma contained high levels of macrophage colony stimulating factor (M-CSF/CSF1), granulocyte-macrophage colony stimulating factor (GM-CSF/CSF2), interleukin-8 (IL-8), and interleukin-34 (IL-34) compared to healthy control levels. Moreover, the level of M-CSF in portal blood was significantly higher than that detected in the peripheral blood of PDAC patients. PDAC CTC aseptically isolated by fluorescence activated cell sorting (FACS) out of freshly collected patient portal blood mononuclear cells (PortalBMC) had elevated RNA expression of IL34 (IL-34 gene) and CSF1 (M-CSF/CSF1 gene) which both signal through CSF1R. PDAC CTC also had high levels of RNA expression for CXCL8, the gene encoding chemokine interleukin-8 (IL-8) which can attract myeloid cells through their CXCR2 receptors. FACS-isolated portal PDAC CTC and M-FB co-cultured ex vivo had increased CTC proliferation, motility, and cluster formation compared to CTC cultured alone. CSF1R and CXCR2 cell surface expression were found on PDAC portal blood CTC and M-FB, suggesting that both cell types may respond to M-CSF, IL-34, and IL-8-mediated signaling. Portal PDAC CTC displayed enhanced RNA expression of CSF1 and IL34, while CTC+M-FB+ clusters formed in vivo had increased RNA expression of CSF2 and IL34. Portal M-FB were found to have high CSF1R RNA expression. CTC isolated from ex vivo 7-day cultures of PDAC patient portal blood mononuclear cells (PortalBMC) expressed elevated CSF1, IL34, and IL8 RNA, and CSF1 expression was elevated in M-FB. Treatment with rabbit anti-CSF1R antibodies decreased CTC proliferation. Treatment of PortalBMC cultures with humanized anti-CSF1R, humanized anti-IL-8, or anti-IL-34 antibodies disrupted CTC cluster formation and increased CTC apoptosis. U937 myeloid precursor cell line cultures treated with conditioned media from PortalBMC ex vivo cultures without treatment or treated with anti-IL-8 and/or anti-CSF1R did not prevent myeloid differentiation in the myeloid precursor cell line U937 to macrophage, dendritic cell, MDSC, and M-FB phenotypes; whereas, U937 cultures treated with conditioned media from PortalBMC ex vivo cultures exposed to anti-IL-34 were significantly inhibited in their myeloid differentiation to all but the M-FB phenotype. PDAC patient T cells that were found phenotypically anergic (CD3+CD25+CTLA4+PD1L1+) in PortalBMC could be re-activated (CD3+CD25+CTLA4-PD1L1-), and displayed increased interferon gamma (IFNγ) production when PortalBMC ex vivo cultures were treated with anti-CSF1R, anti-IL-8, and anti-IL-34 antibodies alone or in combination. These findings suggest that PDAC CTC have the potential to influence myeloid differentiation and/or antigen presenting cell activation in the PDAC portal blood microenvironment, and that disruption of CTC/M-FB interactions may be potential targets for reversing the immunosuppression supporting CTC survival in the portal blood.