Since 2004 Sutro Biopharma Inc. has quietly been building a cell-free protein synthesis platform and working on early research projects with undisclosed partners. Now that it has hired a new CSO and received an injection of venture money, the company will turn to building an internal pipeline of "biosuperiors," compounds that improve upon marketed protein therapeutics.

While the idea of biosuperiors isn't new, Sutro says its biochemical protein synthesis technology will allow it to make modifications that are difficult, if not impossible, to do with cell-based synthesis systems. Last week, it announced a multiyear collaboration with Pfizer Inc. focused on peptides that have been difficult to produce using conventional technologies.