TREM1 and non-small cell lung carcinoma: In conclusion, sTREM-1 may be an interesting surrogate biomarker for TAM activity in NSCLC patients fostering prospective studies investigating whether TREM-1 and PD-1 expression in TAMs both represent the tumor associated M2 state and secondarily whether sTREM-1 can be used as a peripheral blood surrogate marker for this state and potentially as a predictor of checkpoint-inhibitor effectiveness.