Typically, these are motivated by aconspicuous success, a development program that was driven by the strength of beautiful molecular data, and the canonical example these days is PCSK9, a target which seems to feature an almost unprecedented alignment of human genetics, biomarker, and animal model data.
The fiscal and economic challenges are conspicuous: a substantial and intractable gap between public spending and tax revenues in the US at a time of anaemic economic growth.