There are many product development considerations for human gene therapy investigational new drug (IND) applications to ensure the proper ‘Chemistry, Manufacturing, and Controls’ (CMC) is achieved. Unlike small molecule drugs or biologics intended for repeated dosing, gene therapies are designed to modify patient cells directly or indirectly (administration of genetically modified cells to patients) to confer long-lasting therapeutic effects. The complexity of gene therapy manufacturing and therefore control of the processes is continually evolving with the need for disease specific innovations as well as standards across the various gene delivery platforms. As data becomes available on the durability, efficacy, and safety of gene therapy treatments post-administration, new factors must be considered when designing transgene cassettes, gene delivery vehicles, and conditioning treatments for infusion. Such clinical outcomes ultimately affect manufacturing and the continual evaluation of CMC requirements. This article highlights regulatory considerations and new guidance available for gene therapy manufacturing in a continually evolving landscape.