Greater Biosimilar Uptake Found in Medicare Advantage Than Traditional Medicare

A cross-sectional study, published on the JAMA Health Forum, found biosimilar use and market share higher in Medicare Advantage (MA) plans compared with traditional Medicare (TM) plans for most biosimilar products, except for bevacizumab.

Calculated cumulative data from May 2015 to September 2022 was used to evaluate biosimilar market shares for products with at least 1 biosimilar administration on or before September 30, 2019. A total of 20 biosimilar products were included, mainly used in Parts B and C, amongst 7 different product types.

Product types included infliximab, epoetin alfa, bevacizumab, pegfilgrastim, filgrastim, rituximab, and trastuzumab. Each product recorded a cumulative percentage market share from biosimilar introduction and throughout the 36 weeks following introduction. Market share was defined as the number of biosimilar administrations of the total administrations of biosimilars and their reference products.

As of January 2024, the FDA has approved 5 bevacizumab biosimilars, 4 infliximab biosmilars, 1 epoetin alfa biosimilar, 3 rituximab and filgrastim biosimilars each, 5 trastuzumab biosimilars, and 6 pegfilgrastim biosimilars.

Vegzelma (bevacizumab-adcd), Mvasi (bevacizumab-awwb), Zirabev (bevacizumab-bvzr), Alymsys (bevacizumab-maly), and Avzivi (bevacizumab-tnjn) are the brand names for the bevavizumab biosimilars. Renflexis (infliximab-abda), Avsola (infliximab-axxq), Inflectra (infliximab-dyyb), and Ixifi (infliximab-qbtx) represent the approved infliximab biosimilars. Retacrit (epoetin alfa-epbx) is the only epoetin alfa biosimilar. Zarxio (filgrastim-sndz), Nivestym (filgrastim-aafi), and Releuko (filgrastim-ayow) are the filgrastim biosimilar products. Truxima (rituximab-abbs), Riabni (rituximab-arrx), and Ruxience (rituximab-pvvr) make up all the rituximab biosimilars. Kanjinti (trastuzumab-anns), Ogivri (trastuzumab-dkst), Ontruzant (trastuzumab-dttb), Herzuma (trastuzumab-pkrb), and Trazimera (trastuzumab-qyyp) all reference Herceptin (trastuzumab). Lastly, Nyvepria (pegfilgrastim-apgf), Ziextenzo (pegfilgrastim-bmez), Udenyca, (pegfilgrastim-cbqv), Stimufend (pegfilgrastim-fpgk), Fulphila - (pegfilgrastim-jmdb) and Fylnetra (pegfilgrastim-pbbk). In January, the on-body injector version of Udenyca was approved to compete against Neulasta Onpro (on-body injector reference pegfilgrastim).

Out of 6 of the 7 product types, results showed that MA plans had greater biosimilar uptake than TM plans. MA plans had 1.1 and 2.3 times greater uptake for trastuzumab and epoetin alfa biosimilars, respectively, compared with TM plans. All 7 products had a 1.3 (range, 0.7-2.3) median ratio for both MA and TM, with a median difference of 5.7% (range, –4.48% to 9.43%).

However, the products producing the least amount of biosimilar market share differed between MA and TM. For epoetin alfa biosimilars, MA had 5.7% times greater uptake than TM. Bevacizumab biosimilars had the lowest biosimilar market share for MA, with a –4.48% percentage point difference between plan types.

The indicator for bevacizumab was divided into ophthalmic vs oncologic usage. Although the reference product (Avastin) is only indicated for oncology use, it is often prescribed off-label for neovascular age-related macular degeneration. In the ophthalmic group, bevacizumab biosimilars had very low market share. However, market share was higher in TM plans than MA plans.

Data for epoetin alfa biosimilars, which originally had 2 times greater market share in MA plans than TM plans was stratified by end-stage kidney disease (ESKD) and non-ESKD utilization. Like other product types, epoetin alfa biosimilars had 1.5 to 1.7 times greater uptake in MA plans than TM plans. Combining uptake for ESKD and non-ESKD indications resulted in a higher relative weighting of MA biosimilar use.

Study limitations included the potential differences in population characteristics amongst MA and TM. The implementation of the Medicare inflationary rebate could also affect the biosimilar use and market share percentages of MA or TM.

The authors suggested that additional studies should incorporate all avenues of clinical indications. The authors concluded, “Thus, it is important to validate the increased biosimilar uptake observed in MA and investigate potential mechanisms through which managed care may encourage greater biosimilar use.”

Reference:

Kozlowski S, Kwist A, McEvoy R, et al. Biosimilar uptake in medicare advantage vs traditional medicare. JAMA Health Forum. 2023;4(12):e234335. doi:10.1001/jamahealthforum.2023.4335