On the other hand, prime anti-tumor activity and/or control of hormonal excess syndromes has been demonstrated for targeted agents in NENs, resulting in the approval of somatostatin analogs (SSAs) and tryptophan hydroxylase (TPH) inhibitors for gastroenteropancreatic NENs, also referred to as biotherapy, as well as novel molecular targeted therapies (MTTs), such as the mTOR inhibitor everolimus and a number of tyrosine kinase inhibitors (TKIs) with the latter being approved across a diverse spectrum of NEN primaries, including pancreatic NENs and MTC [4,5]. Here, TPH1 is linked to neoplasm.