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ORAL 18 - Non PD1 Immunotherapy and Angiogenesis (ID 114)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
ORAL18.06 - Effect of Anti-VEGF Therapy on MDSCs' Population in the Peripheral Blood of Non-Small Cell Lung Cancer (NSCLC) Patients (ID 689)
10:45 - 12:15 | Author(s): E.K. Vetsika
Bevacizumab is an anti-VEGF monoclonal antibody approved for the treatment of non-squamous NSCLC. It is widely accepted that immunosuppressive mechanisms dominate in patients (pts) with solid tumors, including NSCLC. MDSCs are a heterogeneous population of immature cells of myeloid origin, whose expression is induced by VEGF. We recently identified two monocytic and one granulocytic MDSC subpopulation which are significantly increased and functional in the peripheral blood of NSCLC pts.
Peripheral blood immune cells from 46 pts with unresectable NSCLC were analyzed by flow cytometry before the initiation of chemotherapy and after 3 cycles. Changes in the frequencies of the three MDSCs subpopulations were correlated with clinical outcome. Isolated MDSCs were co-cultured with T cells in order to confirm their functionality through estimation of IFN-γ secretion.
At diagnosis, the CD15(-) monocytic MDSCs’ levels were significantly increased in male pts (p=0.03) and in smokers (p=0.01). Overall, chemotherapy had no effect on the frequency of the distinct MDSC subpopulations. However, after 3 cycles of therapy, levels of all three MDSC subpopulations numerically decreased in responders (n=11) compared to non-responders (n=4). In addition, bevacizumab-based chemotherapy regimens significantly reduced the frequency of the granulocytic MDSC subpopulation when compared to the effect of non-bevacizumab based therapy (p=0.02). Lastly, suppression of IFN-γ secretion in vitro, confirmed the inhibitory effect of isolated MDSCs on T-cell cytotoxic capacity.
These data indicate that although chemotherapy has no effect on the levels of different immunosuppressive MDSC subpopulations, bevacizumab–based regimens seem to exert an effect on the granulocytic MDSC subpopulation. Additional studies are needed in a larger cohort of pts in order to document its impact in the clinical outcome of NSCLC pts.
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