P14.09 Early Expansion of M-MDSCs and High Plasma TSLP Levels As Predictors of Primary Resistance to PD1 Inhibitors in Metastatic NSCLC

Elevation of peripheral myeloid cell populations has been associated with poor response to PD-1 inhibitors in metastatic non-small cell lung cancer (mNSCLC). The mechanisms underlying this relationship remain poorly understood. Thymic stromal lymphopoietin (TSLP), a cytokine involved in T-cell maturation, has been implicated in a complex feedback loop leading to expansion of myeloid populations and tumor growth. We hypothesized that TSLP levels directly correlate with the expansion of myeloid derived suppressor cell (MDSC) populations and sought to explore their association with response to PD-1 inhibitors in mNSCLC.