INFLIXIMAB MARKET SHARE AND ASSOCIATED COST SAVINGS FOLLOWING BIOSIMILAR MARKET ENTRY

Abstract

Abstract BACKGROUND Biologic medications have transformed treatment for autoimmune conditions, including inflammatory bowel disease (IBD), but have also contributed to rising healthcare expenditures in the United States (US). Biosimilars, which are highly similar in safety and efficacy to the originator biologic, were introduced to create competition and reduce cost. Limited studies exist evaluating the impact biosimilars have had on biologic market share and cost savings. The objective of this study was to evaluate the impact infliximab biosimilars have had on the cost and market share of the infliximab originator product. METHODS Infliximab claims were reviewed and analyzed using the Merative MarketScan Commercial Claims and Encounters Database. Using only outpatient claims, both the infliximab originator and biosimilars were identified using Current Procedural Terminology codes from January 1, 2015, to December 31, 2021. Patients with commercial insurance, ages 0 to 64 years, and receiving infliximab for any indication were included. The Medical Care Consumer Price Index was used to adjust for inflation to December 2021 dollars. Outcomes of interest included market share of all infliximab products, cost per infliximab infusion, and cost per vial (one vial=100 mg) of the medication. RESULTS There were 471,748 claims for infliximab infusions that met our inclusion criteria, with 42,100 unique patients, 55% female, and a median age of 40 (inter-quartile range (IQR) 26 – 52) years old at the time of medication initiation. Indications for infliximab products included IBD (67%), rheumatoid arthrtiis (18%), psoriasis (9%), ankylosing spondylitis (5%), other (4%), with some patients receiving infliximab for multiple indications. Utilization of infliximab biosimilars increased over time, reaching the highest utilization in December 2021, accounting for 24% of the market share. The median cost of the infliximab originator peaked at $1,491 per vial in December 2017, 13 months after market entry of the first biosimilar (infliximab-dyyb). The cost of the infliximab originator then decreased by 45% over time, reaching a low of $821 per vial in December 2021. Had infliximab biosimilars not been introduced to the market, the projected cost of the infliximab originator in December 2021 would have increased by 20% to $1793 per vial. Thus, infliximab biosimilars contributed to a theoretical decrease of 55% in the cost of infliximab originator during the time period studied. CONCLUSIONS The market share of infliximab biosimilars in the US has steadily increased since their introduction in 2016. The competition of infliximab biosimilars has contributed to the decrease in cost of both the infliximab originator and biosimilar products. Future studies are needed to determine if patients are seeing an out-of-pocket savings because of biosimilar introduction.