Measuring the First Mover Advantage in US Biosimilar Markets

Objectives We project market share trends to estimate the median long-run, steady-state market share advantage of first movers in US biosimilar markets. Methods We used the IQVIA National Sales Perspective data to calculate monthly active pharmaceutical ingredient unit sales in 6 US biosimilar markets (bevacizumab, filgrastim, infliximab, pegfilgrastim, rituximab, and trastuzumab) from the third quarter of 2015 through the fourth quarter of 2023. We fit trends to each product’s share of the biosimilar market and projected long-run steady-state values using modified exponential decay functions for first movers and logistic growth functions for later entrants. We compared the median steady-state market share of the first mover to that of later entrants. Results In 4 of 6 US biosimilar markets studied, we project the first-mover to earn more market share in the long run than all later entrants. First movers will earn a long-run steady-state market share that is between 8.9 and 12.0 percentage points higher than the second entrant, depending on the number of biosimilar competitors in the market. Considering the size of biologic markets, each percentage point potentially represents $5 million in annual sales. Conclusions In 4 of 6 US markets analyzed, the first biosimilar entrant has a long-run steady-state advantage over all later entrants, which is in addition to the short-run benefit of higher prices. To date, several biosimilar developers have entered the US market before resolving all patent issues. The first mover’s long-term advantage may be sizable in dollar terms, which could partially explain this behavior.