Since the 1985 approval of the first recombinant human growth hormone (hGH, such as Protropin/somatrem human growth hormone from Genentech, now Roche), the number of clinical indications for therapy with hGH has steadily increased (1). That led to a highly successful drug with more than US$3 billion sales in 2011 (2). Even so, hGH shares a common problem with most other first-generation protein therapeutics: a very short plasma half-life of just about two hours in humans. Because such biologics are…