The cost of the infliximab biosimilar (infliximab-dyyb) for rheumatoid arthritis (RA) was only moderately less expensive than the biologic infliximab and exceeded $14,000 annually under Medicare Part D, according to research published in JAMA.

Biologic specialty drugs represent only 2% of prescriptions in the United States, but accounted for 38% of drug spending in 2015, as well as 70% of growth in drug spending from 2010 to 2015. Biologics for RA were in the top 15 of Medicare expenditure drugs in 2015, and RA biologics cost over $14,000 per year. The researchers examined coverage and cost sharing for infliximab-dyyb, the first RA biosimilar released in 2016, compared with biologic infliximab. They analyzed nationwide benefits data for all Medicare Part D plans from June 2017 to calculate out-of-pocket cost requirements and mean total cost for infliximab and infliximab-dyyb, assuming a standard dosing regimen of 8-weeks with 6.5 prescriptions per year.

Out of the total 2547 plans, 96% covered infliximab, whereas only 10% covered infliximab-dyyb, which had a slightly lower mean total cost per 8 weeks and annually compared with infliximab ($2185 vs $2667 and $14,202 vs $17,335, respectively). However, because all plans required coinsurance cost-sharing for infliximab-dyyb prescriptions and set copay rates similar to infliximab (26.6% vs 28.4% of drug cost), projected out-of-pocket costs annually were higher for infliximab-dyyb than for infliximab ($5118 vs $3432 without gap discounts).

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Researchers conclude that although infliximab-dyyb was only 18% less expensive than biologic infliximab, it would cost patients $1700 more out of pocket. They note that “although biosimilar gap discounts begin in 2019, infliximab-dyyb may still not significantly reduce Part D beneficiaries’ out-of-pocket costs given its high price and coinsurance cost-sharing similar to infliximab. Further policies are needed to address affordability and access to specialty drugs.”

Disclosures: Dr Yazdany has received an independent investigator award from Pfizer.

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Yazdany J, Dudley RA, Lin GA, Chen R, Tseng CW. Out-of-pocket costs for infliximab and its biosimilar for rheumatoid arthritis under Medicare Part DJAMA. 2018;320(9):931-933.