U.S. patients gained access to lower-priced Humira biosimilars in 2023, but rebate practices by drug makers and PBMs limit competition, keeping out-of-pocket costs high. CVS Caremark and Express Scripts steer patients to preferred, not necessarily cheapest, biosimilars, preserving rebate-like strategies. Despite biosimilar market share growth, originator Humira still dominates with 82% share, contrasting with Europe's 65% five years ago.