Co-development of drugs and companion diagnostics might need timely and coordinated approval decisions from different bodies to meet the requirements of joint clinical trial schemes and eventually the approval of both the drug and its associated test. In addition, the path to get a stratified indication approved is not always clear. In this respect, the status of retrospective analysis deserves clarification. Besides, the concept of qualification is evolutionary and clear guidelines are missing. Therefore, the regulatory authorities should be contacted early enough to provide input, give advice and hence allow adjusting strategies on time. .
