Comparative Immune profiling in Pancreatic Ductal Adenocarcinoma Progression Among South African patients

Introduction Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive cancer with a 5-year survival rate of only 11%. PDAC is characterized by an immunosuppressive microenvironment; thus, there have been multiple attempts to target it, although with little success. A better understanding of the immune landscape in PDAC is required to help elucidate the roles of these cells for effective targeting. This study investigated the expression of circulating key immune cell markers in South African PDAC patients. Method Blood samples were obtained from a total of 34 PDAC patients consisting of 22 resectable (RPC), 8 locally advanced (LAPC) and 4 metastatic (MPC), 6 Chronic Pancreatitis (CP), and 6 healthy volunteers (HC). Immunophenotyping, real-time polymerase chain reactions (PCR), enzyme-linked immunosorbent assay (Elisa), and reactive oxygen species (ROS) assays were conducted. Statistical analysis was conducted in R (version 3.6.1) and Wilcoxon and Kruskal-Wallis rank-sum tests were used to compare between groups. Kaplan-Meier analysis and Spearman’s rank test were used for survival and correlation analyses, respectively. Results Granulocyte and neutrophil levels were significantly elevated while lymphocytes decreased with PDAC severity. The total percentages of CD4+, CD8+, and CD3+CD4-CD8- T-cells increased across the group. Of note are the reduction of CD16+ NKTs across the RPC ( p = 0.002), LAPC ( p = 0.01), and MPC ( p = 0.017) groups when compared to HC. Both NK ( p = 0.0047) and NKTs ( p = 0.0027) increased in RPC but decreased in both LAPC and MPC when compared to HC. Although there was no statistical correlation or differences observed when comparing the PDAC groups with the control groups, RPC had the highest foldchange for both CD4 (11.75 ± 44.31) and CD3 (30.47 ± 75.01) while the LAPC group had the highest fold change for CD8 (3.86 ± 7.35) and CD16 (51.69 ± 108.9) genes compared to MPC. The inflammatory status of PDAC was assessed by DEPPD levels of serum which were elevated in RPC ( p = 0.003) and LAPC ( p = 0.008) but decreased in MPC ( p = 0.025), compared to the HC group. ROS was shown to be positively correlated with GlycA (R=0.45, p = 0.00096). Conclusion The expression of these immune cell markers observed in this pilot study provides insight into their potential roles in tumour progression in the patient group and suggests their potential utility in the development of immunotherapeutic strategies. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Research reported in this publication was supported by the South African Medical Research Council under a Self-Initiated grant, two South African National Research Foundation grants (Grant numbers: 138367 and 121277) and the Cancer Association of South Africa (CANSA). The views and opinions expressed are those of the authors and do not necessarily represent the official views of the funders. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics clearance for this study was obtained from the Human Research Ethics Committee of the University of the Witwatersrand (Study number:M190681). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors