What “development” are you referring to, exactly? The alternate indications in many cases are already well known (as they were in the referenced article).
The clinical studies needed to support receiving approval to market the old drug for a new indication, as well as whatever lifecycle management and post-marketing surveillance activities (Phase IV) that are required. The alternate indications may be well-known but marketing for an off label indication is not permitted (as in, they actually jail CEOs and executives for that).