Analysis Details Impact of Biosimilar Introduction on Biologic Prices, Cost

Alvaro San-Juan-Rodriguez, PharmD

A new analysis from investigators at the University of Pittsburgh is shedding light on the impact biosimilar competition can have on pricing for biologic therapies.

Examining trends in list prices, net prices, and discounts for originator biologics facing biosimilar competition from 2007 to 2018 revealed more about how the introduction of biosimilars impacted pricing in the real world versus previous estimates.

To further detail trends, investigators conducted an analysis of quarterly estimates of list prices, net prices, Medicaid discounts, and discounts in other payers for branded products reported by publicly traded companies from January 2007 to June 2018 from SSR Health. For the purpose of their analyses, investigators selected filgrastim, pegfilgrastim, infliximab, and insulin glargine as study drugs—noting they were the only originator biologics the face competition from biosimilars or other within-molecule substitutes.

Specific biosimilars examined in the study included filgrastim-sndz, filgrastim-aafi, pegfilgrastim-jmdb, infliximab-dyyb, and infliximab-abda. Tbo-filgrastim and insulin glargine were the only within-molecule substitutes included.

To examine trends, investigators calculated quarterly net prices as the ratio between sales and number of units sold and discounts were calculated as the ratio between difference in list and net prices and the list prices. Investigators noted net prices and discounts captured manufacturer con sessions and not solely rebates. Additionally, investigators calculated mean list and net prices and the mean discounts in Medicaid and other payers for every drug and year examined.

Upon analysis, investigators observed list and net price increases for filgrastim in parallel each year by a mean of 5.1% (95% CI: 4.0%-6.2%) until the introduction of the first bio similar in 2015. Following the introduction of the first biosimilar, list prices began to stagnate and net pries began to decrease by a mean of 7.7% annually (95% CI: −19.9%-4.6%).

A similar trend was noted with pegfilgrastim, as list and net prices increased annually by a mean of 7.5% (95% CI: 6.2%-8.8%) and 4.9% (95% CI: 1.3%-8.5%), respectively, until the introduction of its first biosimilar. Following the introduction of that biosimilar in 2018, list prices began to stagnate and net prices dropped by -7.4% (−$269.2 of $3640.1).

In regard to infliximab, list and net prices increased by a mean of 6% (95% CI: 4.2%-7.8%) and 6% (95% CI: 3.9%-8.2%), respectively, from 2007 to 2013. Net prices began to decrease by a mean of -13.6% (95% CI: −19.7% - −7.5%) per year after the introduction of its first biosimilar in 2017, however, investigators noted net prices had decreased by a mean of -1.3% (95% CI: −9.7%-7.2%) between 2013 and 2017.

When examining insulin glargine, annually increase of 14.7% and 8.8% were observed for list and net prices, respectively, from 2007 to 2014. Investigators noted list price growth slowed to a mean of 5.8% annually between 2015 and 2019. Conversely, net pries began to decrease by a mean of 14.4% annually beginning in 2015 and this jumped to a mean of -23.5% after the introduction of a biosimilar in 2017.

Medicaid discounts increased by 20.1% for filgrastim, 31.2% for pegfilgrastim, by 33.8% for infliximab, and by 35.2$% for insulin glargine. In payers outride of Medicaid, investigators noted increases of 20.3% (95% CI: 12.1-28.5) for filgrastim, by 23.4% (95% CI: 15.6-31.2) for pegfilgrastim, by 50.6% (95% CI: 49.4-51.7) for infliximab, and by 76.1% (95% CI: 74.1-78.1) for insulin glargine.

“Our findings show that biologics that faced biosimilar competition—even without interchangeability—showed marked reductions in net prices and leveling off of list price increases,” investigators wrote.

The research letter, titled “Trends in List Prices, Net Prices, and Discounts for Originator Biologics Facing Biosimilar Competition,” was published in JAMA Network Open.