In a recent interview, Roche CEO, Stefan Schwan said that Roche determined which diseases it went after based on the science. He said their main criterion wasn't the size of the patient population but rather the medical benefit they could bring to a single patient. In responding to a direct question, Schwan indicated that Roche could pursue rare diseases too if the science dictated it.
This is in keeping with previous market rumors where Roche was linked to being a possible purchaser of Alexion Pharmaceuticals or Biomarin -- bothactive in rare (or orphan) disease spaces. Neither bid is considered much of a possibility now but the rumors arise as Roche really hasn't ruled out working in these areas. Schwan indicated that if there was an interesting opportunity with rare diseases he'd be "open to look at it." See Yahoo finance.
Posted by Bruce Lehr Oct 23rd 2013