IDO1 and neoplasm: To further investigate the immunological characteristics of the tumour slice culture, the levels of soluble (s)BTLA, sCD28, sLAG3, sCD40, sCD80, sCD137, sCD152 (CTLA-4), sGITR, sHVEM, IDO-1, sPD-1, sPD-L1, sPD-L2 and sTIM3 were measured in PCTS supernatants of patients with LM-NEN.