Biosimilars engage in low levels of direct-to-physician marketing relative to reference biologics.

Biosimilars have the potential to greatly reduce US spending on biologic drugs, but uptake of these competitor products varies. We used Open Payments data from 2014 to 2022 to proxy for direct-to-physician marketing and compared levels of activity between biologic and biosimilar drug manufacturers. Our analysis focused on 6 reference biologics that recently faced competition in the years immediately before and after the launch of the first biosimilar. We used Medicare Part B dosage units to measure market penetration of biosimilars and its relationship with biosimilar marketing activity. Last, we conducted a sensitivity test, comparing payments for primarily office- or hospital-based physicians, using affiliations constructed from Medicare Carrier claims. Reference biologic manufacturers greatly reduced the amount of direct-to-physician marketing in the post-launch period. Biosimilar manufacturers generally engaged in low levels of activity relative to the historic performance of reference biologics. These trends were consistent across office- and hospital-based physicians. The intensity of biosimilars' direct-to-physician marketing also had no apparent relationship with achieved market penetration. Our findings demonstrate that persistently high market shares of reference biologics cannot be explained by ongoing direct-to-physician marketing activities. At the same time, while such activities could educate physicians or induce switching, biosimilar entrants engaged in little direct-to-physician marketing.