Neoadjuvant Chemotherapy with Gemcitabine Plus Nab-paclitaxel Reduces the Number of Cancer-associated Fibroblasts Through Depletion of Pancreatic Stroma.

BACKGROUND: In this study, the effects of neoadjuvant chemotherapy (NAC) on cancer-associated fibroblasts (CAFs) in pancreatic cancer stroma were investigated.

MATERIALS AND METHODS: Density of α-smooth muscle actin (αSMA)-positive fibroblasts in resected surgical specimens from untreated patients, patients receiving conventional gemcitabine plus S-1 (GS), and patients receiving gemcitabine plus nab-paclitaxel (GnP) was determined by hybrid cell counting. 18F-Fluorodeoxyglucose positron-emission tomography (FDG-PET) scans and carbohydrate antigen 19-9 (CA19-9) concentrations were used to assess tumor activity before and after chemotherapy in the GnP group.

RESULTS: In this retrospective study of 65 patients, αSMA expression was reduced in the GnP group, as revealed by markedly disorganized collagen and a low density of αSMA-positive fibroblasts. There were significantly fewer αSMA-positive fibroblasts in the GnP than in the untreated and GS groups, but there was no significant difference between the latter two groups. αSMA density reflected a decrease in standardized uptake value on FDG-PET, but not CA19-9 concentration, after GnP chemotherapy.

CONCLUSION: These data suggest that the GnP regimen induces stromal depletion, resulting in fewer CAFs.