Optimal Organ for Patient-derived Xenograft Model in Pancreatic Cancer and Microenvironment that Contributes to Success.

BACKGROUND: We aimed to investigate the difference in engraftment rates depending on the transplant site for a patient-derived xenograft (PDX) of pancreatic ductal adenocarcinoma (PDAC) and the effects of the microenvironment on engraftment. MATERIALS AND METHODS: Frozen cancer tissues from PDAC tumors were used, and tumor fragments were directly implanted into the subcutaneous, orthotopic pancreas, peritoneum, and liver of X-linked severe combined immunodeficiency (XSCID) rats. We assessed the success of engraftment in each organ. Additionally, to evaluate the effect of the microenvironment in each organ, we performed immunohistochemical analysis. RESULTS: Subcutaneous transplantation was successful in 8 of 10 PDAC cases (16 of 30 rats). This was a higher rate than for other organ transplants. The vascular endothelial cells in the stroma were replaced with those from rats instead of humans. Vascular endothelial growth factor-A (VEGF-A) and cluster of differentiation-31 (CD31) was significantly more strongly expressed in the subcutaneous transplantation model (VEGF-A: p<0.001, CD31: p=0.0036). CONCLUSION: The engraftment rate was significantly higher for the subcutaneous PDX model than for the orthotopic pancreatic, peritoneal, and liver PDX models. Blood vessels of the PDX stroma had been replaced by rat-derived vessels instead of the original human vessels, suggesting that angiogenesis in the PDX microenvironment may be a major factor in engraftment.

Establishment of a Liver Transplant Patient-derived Tumor Xenograft (PDX) Model Using Cryopreserved Pancreatic Ductal Adenocarcinoma.

BACKGROUND/AIM: There is rapid progression and widespread use of patient-derived tumor xenografts (PDX) in translational pancreatic cancer research. This study aimed to establish a liver transplant PDX model using cryopreserved primary pancreatic ductal adenocarcinoma (PDAC). PATIENTS AND METHODS: Primary PDAC from 10 patients were cryopreserved and transplanted into immunodeficient mice using the liver pocket method. H&E staining and immunohistochemical staining, such as Ki-67, p53, Smad4, and MUC1 were used to evaluate engraftment and histological similarities. RESULTS: Patient-derived xenograft placement was successful in six cases (60%), and 10 mice (33.3%). The Ki-67 index of primary PDAC and the cryopreservation duration were significantly related to successful engraftment (p=0.003 and p=0.007, respectively). CONCLUSION: In this study, we succeeded in establishing a liver transplant PDX mouse model as a preclinical platform. The successful engraftment was affected by the cryopreservation duration and could be detected by the Ki-67 index.

Preoperative Neutrophil-to-lymphocyte Ratio Predicts Tumor-infiltrating CD8+ T Cells in Biliary Tract Cancer.

BACKGROUND/AIM: This study evaluated the prognostic significance of preoperative neutrophil-to-lymphocyte ratio (NLR) and CD8+ tumor-infiltrating lymphocytes (TILs), and whether preoperative NLR was associated with CD8+ TILs in biliary tract cancers (BTCs). PATIENTS AND METHODS: A total of 154 patients with BTCs who underwent surgery were enrolled in this study. We obtained neutrophil and lymphocyte counts, and calculated NLR from preoperative peripheral blood samples. CD8+ TILs were identified by immunohistochemical staining. RESULTS: The overall survival (OS) and recurrence-free survival (RFS) of patients with high NLR were shorter than those with low NLR. The OS and RFS of patients with high CD8+ TILs were longer than those with low CD8+ TILs. Preoperative NLR and CD8+ TILs were negatively correlated. CONCLUSION: NLR and CD8+ TILs were associated with OS and RFS in BTCs. NLR can predict CD8+ TILs infiltrating the cancer microenvironment.