Somavert® (pegvisomant), was approved in 2003 for the treatment of acromegaly (Pradhananga et al., 2002; Parkinson et al., 2003) and it is obtained by nonspecific conjugation of an analog of human growth hormone (hGH) with 4–6 equivalents of PEG-NHS (5kDa). Here, GH1 is linked to acromegaly.