In order to maximize potential commercial return, biosimilar developers must adopt clear and effective strategies that leverage their internal capability and potentially capture the expertise of partners. Partnership activity in the biosimilar space increased 34% in 2013 compared with 2012, with 34 new partnerships formed in 2013 compared with 26 in 2012. Biosimilar developers need to assess the optimal strategies to implement early in product development to differentiate their biosimilar product from rival biosimilars and from the reference biologic. Companies that market reference brands are at risk of losing considerable revenue and need to adopt defensive strategies to limit or offset sales erosion. For both of these types of market players, determining the optimal strategy is challenging given the highly dynamic biosimilars environment and the need to factor in the impact of the evolving perceptions of key stakeholders such as physicians and payers.