Although it appears today that biosimilars for Enbrel® will not be launched before 2029, a budget impact analysis presented at the Academy of Managed Care Pharmacy (AMCP) Nexus meeting hints at how much money is being left on the table until then.
Researchers from Xcenda and Sandoz (the latter of which has an approved etanercept biosimilar) assessed the situation from the perspective of a US commercial 1 million member plan with a 3% annual growth rate. The price of the biosimilar was pegged to 15% below the 2020 wholesale average cost of the reference product. They addressed two potential scenarios for patients already receiving chronic therapy: (1) 5% uptake at baseline and 5% monthly increase in uptake (i.e., 60% marketshare by end of year 1) and (2) 5% baseline utilization and 7% monthly gains in marketshare (i.e., 82% by end of year 1). Marketshare increases in years 2 or 3 were not considered. For treatment naïve patients, a 12% baseline uptake and 5% monthly increase was assumed through year 1.
In scenario 1, a biosimilar etanercept would be administered to 1,077 patients compared with scenario 2, in which 1,453 patients would receive the biosimilar. After the first year, the total net cost savings with biosimilar etanercept amounted to nearly $6.5 million in scenario 1 and $8.6 million in scenario 2. By the end of year 3, annual savings (not cumulative savings) would grow to $12.8 million with 60% marketshare of the biosimilar or $17.2 million with 82% marketshare. Three-year savings might be as high as $42.4 million in scenario 2. Average cost savings per patient switched to the biosimilar from Enbrel would be $11,069 per year and $11,071 for the two scenarios, respectively.
Whereas this budget impact model has several limitations, including potential double-counting of hypothetical members who have more than one inflammatory indication, it does offer insight into the possible value of biosimilars at a relatively modest discount (but a fairly aggressive switching schedule).
When asked about the effect of Enbrel price increases on model savings, Edward Li, PharmD, of Sandoz, told BR&R, “Our model was constructed earlier this year (April), and therefore the WAC pricing that we used is reflective of that time period. We did not account for price increases of the reference drug over time, because we cannot speculate what other companies will do. Therefore, this is the more conservative estimate of the savings; if there are indeed price increases, then the savings will be larger.”
Price increases from Amgen on this agent does seem highly probable. In the past, our own simple calculations of the impact of obstructed access to biosimilar discounts have resulted in distressing future numbers that illustrated not so much biosimilar etanercept savings but excess costs having been paid to reference manufacturers because of delayed marketing. If the 2029 date holds, giving Amgen 31 years of exclusivity on this agent, a 15% discount will be cold comfort: It may be considerably less paid by a health plan, but it won’t feel like savings at all.