Trastuzumab Biosimilars Successfully Drove Down Prices

While biosimilar uptake in the United States has been slow, trastuzumab biosimilars have been the best example of how biosimilars can reduce the price of biologics through increased competition.

In new research published in Health Affairs,¹ researchers evaluated changes in average sales price (ASP) and net price for the trastuzumab market.¹ When the first trastuzumab biosimilar (Kanjinti) entered the market, the reference product (Herceptin) immediately began to lose market share and continued to do so with each subsequent biosimilar to enter the market. In addition to Herceptin, there are 4 other trastuzumab biosimilars on the market: Ogivri, Trazimera, Herzuma, and Ontruzant.

“Eight years into the US experience with biosimilars, the trastuzumab market presents a novel situation in which multiple biosimilars entered during a short period,” they explained.

The authors used administrative Medicare fee-for-service claims data from January 2019 to December 2020. All of the biosimilars launched with a price lower than the reference product and all products saw their ASP decline from the first quarter of 2019 to the second quarter of 2022. During this time, the reference product’s ASP fell 21%.

Kanjinti had the lowest ASP for most of the study period. During 2 quarters, Ogivri had a lower ASP, but Kanjinti soon cut its ASP to once again have the lowest ASP, the authors found. By the second quarter of 2022, ASPs ranged from 28% to 58% of the ASP of the reference product prior to biosimilar competition entering the market.

By December 2020, the reference product only had 45.3% of the market share, followed by Kanjinti with 39.6%. There was great variation of market share of the biosimilars by state with Kanjinti having 100% market share in Washington, DC, and Delaware, compared with Alaska, where Ogivri had about 75% market share and Trazimera had the remaining share. In Maine, Trazimera had nearly 50% of the market. However, Kanjinti was heavily the favorite with more than 50% market share in all but 8 states.

According to regression analyses adjusted for state and time, Kanjinti’s share of the biosimilar market fell as uptake of biosimilars increased. As Kanjinti’s share fell, Ogivri’s, Trazimera’s, and Herzuma’s shares increased.

“This suggests that despite Kanjinti’s first-mover advantage, multiple biosimilar products are viable,” the authors wrote.

These findings are especially important now, as the US market is poised for a similar situation with multiple biosimilars entering the market in a short timeframe. There are 8 biosimilars of adalimumab (Humira) expected to launch in July following the first adalimumab biosimilar (Amjevita), which launched January 31, 2023.² The challenge with adalimumab biosimilars is that the product is both physician administered and can be dispensed through retail channels, which gives pharmacy benefit managers and others a larger role than they had with the trastuzumab biosimilars. As a result, adalimumab biosimilars may not exert as much price pressure on the biologic as trastuzumab biosimilars did.

In addition, the presence of multiple biosimilars for a product may complicate patient care.

“Insurers now designate ‘preferred’ versions of biologic drugs, forcing hospitals to stock multiple versions, manage more complex inventories, and verify patients’ insurance coverage terms before treatment,” the authors concluded.

References

1. Chen AJ, Kaiser KM, Gascue L, Manetas M-A, Van Nuys K. Cancer drug trastuzumab and its biosimilars compete on price for market share. Health Affairs (Millwood). 2023;42(6):779-784. doi:10.1377/hlthaff.2022.01448

2. Joszt L. First Humira biosimilar, Amjevita, launches in the United States. The American Journal of Managed Care. January 31, 2023. Accessed June 5, 2023. https://www.ajmc.com/view/first-humira-biosimilar-amjevita-launches-in-the-united-states