Why did biosimilars gain so little share at first?

When biosimilars launched through 2023, US uptake was flat at around 2% to 3%. A key reason was the rebate system. Some biosimilars launched in both high-list-price and low-list-price versions, because PBMs earning rebates tied to list price had little incentive to favour low-list options. Drug Channels noted the largest PBMs' 2024 formularies generally supported the gross-to-net bubble for Humira biosimilars. AbbVie also defended its position with rebates and by moving patients to newer drugs. The result was that for more than a year after biosimilars became available, most patients continued on branded Humira, and payers and patients saw little of the expected savings. For critics, this showed that approval of biosimilars does not guarantee competition when intermediaries control access.