Within the biopharmaceuticals portfolio, monoclonal antibodies and fusion proteins encompass the largest global market share and have a remarkable efficacy in treatment of several major diseases.Established platform purification processes are available for monoclonal antibodies and due to their similarity, these processes can be used, thus decreasing the development duration.The quality attributes to be controlled for the mAb modalities are well characterized and significant information is available in public domain.Fusion proteins on the other hand have distinctive structures since they are engineered by combining two different protein domains preferably by peptide linkers.This linking of two protein domains out of their natural form, lead to generation of complex impurities which are less understood as compared to mAb modalities.If the fusion protein does not have an Fc portion then there is an addnl. challenge of capturing the protein from cell culture harvest stage.Consequently, the risk of complex, difficult to remove HCPs in the product increases.This gives rise to an urgent need for innovation using novel technol. for purifying fusion proteins with unique structures thus enabling control of the complex difficult-to-remove impurities.In this presentation an integrated purification strategy for a complex non-mAb fusion protein expressed in mammalian expression systems is described, with primary focus on issues encountered during development, scale up and technol. transfer.In this study using a combination of resin and single-use technol. with non-conventional mode of chromatog., an integrated process was developed to control HCPs, high and low mol. weight species , viruses to acceptable levels.This study also details the strategy to address potential challenges related to complex protein associated HCPs and low mol. weight species by performing in depth characterization of the impurities and subsequently design the solution for controlling these impurities.