SSTR5 and pituitary tumor: Therefore, based on the high binding affinity of PAS for SST5 (occurring in the subnanomolar range) [16], and the well described role of SST5 in the biological effects of PAS in other pituitary tumors (e.g., corticotroph tumors) [43], a potential advantage in combining OCT and PAS in the treatment of somatotroph tumors claimed to be investigated.