The study population consisted of 34 patients who received everolimus as a systemic treatment for non-functioning NETs, pheochromocytoma, or extra-adrenal paragangliomas....Patients with low sTGF-β level (<26.12 ng/mL) at baseline showed better progression-free survival (PFS) than those with high sTGF-β level (22.73 months vs. 12.97 months, p=0.019). Similarly, patients with low sPD-L1 level (<6.65 ng/mL) at baseline tended to have longer PFS than patients with high sPD-L1 level (18.97 months vs. 7.37 months, p=0.095). In multivariate analysis, the prognostic value of baseline sTGF-β for PFS retained its significance in patients with non-functioning NET (Hazard ratio 6.04, 95% confidential interval 1.13-32.38, p=0.036).