Gemcitabine reduces MDSCs, tregs and TGFβ-1 while restoring the teff/treg ratio in patients with pancreatic cancer.
BACKGROUND
Cancer immunotherapy can be potentiated by conditioning regimens such as cyclophosphamide, which reduces the level of regulatory T cells (tregs). However, myeloid suppressive cells are still remaining. Accordingly to previous reports, gemcitabine improves immune status of cancer patients. In this study, the role of gemcitabine was further explored to map its immunological target cells and molecules in patients with pancreatic cancer.


METHODS
Patient blood was investigated by flow cytometry and cytokine arrays at different time points during gemcitabine treatment.


RESULTS
The patients had elevated myeloid-derived suppressor cells (MDSCs), and Tregs at diagnosis. Myeloid cells were in general decreased by gemcitabine. The granulocytic MDSCs were significantly reduced while monocytic MDSCs were not affected. In vitro, monocytes responding to IL-6 by STAT3 phosphorylation were prevented to respond in gemcitabine medium. However, gemcitabine could not prevent STAT3 phosphorylation in IL-6-treated tumor cell lines. TGFβ-1 was significantly reduced after only one treatment and continued to decrease. At the same time, the effector T cell:Treg ratio was increased and the effector T cells had full proliferative capacity during the gemcitabine cycle. However, after a resting period, the level of suppressor cells and TGFβ-1 had been restored showing the importance of continuous conditioning.


CONCLUSIONS
Gemcitabine regulates the immune system in patients with pancreatic cancer including MDSCs, Tregs and molecules such as TGFβ-1 but does not hamper the ability of effector lymphocytes to expand to stimuli. Hence, it may be of high interest to use gemcitabine as a conditioning strategy together with immunotherapy.
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory C11 2nd floor, Uppsala University, Dag Hammarskjoldsvag 20, 751 85, Uppsala, Sweden.
Emma
E
Eriksson
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory C11 2nd floor, Uppsala University, Dag Hammarskjoldsvag 20, 751 85, Uppsala, Sweden.
Jessica
J
Wenthe
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory C11 2nd floor, Uppsala University, Dag Hammarskjoldsvag 20, 751 85, Uppsala, Sweden.|Department of Oncology, Uppsala University Hospital, Uppsala, Sweden.
Sandra
S
Irenaeus
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory C11 2nd floor, Uppsala University, Dag Hammarskjoldsvag 20, 751 85, Uppsala, Sweden. angelica.loskog@igp.uu.se.|Lokon Pharma AB, Uppsala, Sweden. angelica.loskog@igp.uu.se.
Angelica
A
Loskog
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory C11 2nd floor, Uppsala University, Dag Hammarskjoldsvag 20, 751 85, Uppsala, Sweden.|Department of Oncology, Uppsala University Hospital, Uppsala, Sweden.
Gustav
G
Ullenhag
Gemcitabine; MDSCs; Pancreatic cancer; TGFβ; Tregs
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