 The biotherapeutic drug market has grown significantly over the past few decades due to the success of existing drugs such as monoclonal antibodies and biosimilars, as well as the recent introduction of novel cell and gene therapies. However, one of the biggest challenges faced by developers is the potential for immune responses which can lead to safety or efficacy issues. To address this issue, quality by design, QBD, principles should be applied during the discovery phase, followed by the development of quality essays and management strategies in the clinic, and finally, the effective presentation of this information in regulatory documents. This article was authored by Tyler C. Vandevaart, David B. Horton and Stephen B. Johnson.