Cancer biosimilars tied to lower monthly costs

A monthly gap of $3,820 separated the average insurer costs: $8,959 for patients who exclusively used a biosimilar, compared with $12,779 for those who exclusively used the original biologic. The UCLA Health Jonsson Comprehensive Cancer Center study also found lower average monthly out-of-pocket payments: patients paid $118.90, versus $158.40 for originator users.

The researchers examined health insurance claims for 14,655 patient-drug pairs involving people who began bevacizumab, rituximab or trastuzumab between 2020 and 2023. They followed treatment and spending for 12 months, comparing patients who stayed exclusively with a biosimilar, stayed with the originator, or switched between the two. The findings were published in JAMA Oncology.

Biosimilars are not conventional generics. They are highly similar versions of biologic medicines—complex treatments made using living cells—and have no clinically meaningful differences from their original products. Their arrival was associated with a 3.8% per year decline in the average sales price of the three originators, while the average sales price of the 12 biosimilars included in the study declined by 12.4% per year.

The pattern suggested that biosimilars were adopted primarily by patients starting treatment: 59.4% exclusively used a biosimilar during their first 12 months, while 32.5% exclusively used the originator. Only 6.9% switched from the originator to a biosimilar, and 1.2% moved in the opposite direction. Originator market share also declined by about 30% annually among patients with commercial insurance and 31.5% in Medicare Part B.

So, concretely, the immediate benefit is not an identical reduction in every patient’s bill. The savings were much larger for insurers than for patients, but the $39.50 per month difference could help cover other treatment or living expenses. The study used retrospective claims data, meaning its results show an association between biosimilar use and lower costs rather than proving that biosimilars alone caused every reduction.