Investigators speculate on why infliximab biosimilars don’t have a larger market share by now.
This study has been updated to note that Avsola launched in July 2020.
The uptake of infliximab biosimilars in the United States is slow but tracks closely to the experience in Europe, where after 2 years infliximab biosimilars assumed a large share of the market, according to a new study.
Infliximab biosimilar uptake has lagged filgrastim biosimilar uptake, and investigators theorized providers find it easier to prescribe a change of medicine in the case of filgrastim, which is for blood cell regeneration following radiotherapy, than for infliximab, which is for rheumatoid arthritis and related conditions. They said physicians are naturally more cautious about changing medicines for chronic conditions that are well controlled with the initial medication.
Investigators analyzed uptake of infliximab biosimilars in the US Medicare population and reported that in the 2 years after the November 2016 launch of the first infliximab biosimilar (Inflectra), “biosimilars captured only 10% of the infliximab market and lowered reimbursements by 17%.” Renflexis was launched in July 2017.
These were the second and third biosimilars to be launched in the United States. The uptake of these biosimilars and the corresponding reduction in costs have not measured up, the authors commented, compared with results of the first biosimilar launch in the country (filgrastim, Zarxio). This biosimilar “had strong adoption after just 2 years, capturing 40% of the market and lowering unit prices by 25%.”
Trends in Infliximab Originator and Biosimilar Use
Using Medicare fee-for-service quarterly claims data, the researchers analyzed trends in use, reimbursement, and switching between the reference infliximab (Remicade) and its biosimilars from January 1, 2017, to December 31, 2018.
Total infliximab administrations decreased by 3.9% from Q1 of 2017 to Q4 of 2018. The proportion of biosimilar administrations increased over that time from 0.5% to 10.5% of the total. The authors noted this pattern was similar across approved infliximab indications.
In the first quarter of 2017, reimbursement per 10 mg for the newly launched biosimilar Inflectra was higher than for Remicade ($101.62 vs $86.87). After the second biosimilar (Renflexis) was introduced in May 2017, the relative biosimilar reimbursement began to fall, reaching $65.36 per 10 mg in the fourth quarter of 2018, 17.1% lower than the $78.86 reimbursement for the originator at that time.
Patients, Physicians, and Switching
The majority of both new and returning patients taking infliximab used the reference product. Among new patients,17.4% used a biosimilar, and 10.8% of returning patients used a biosimilar. Almost all new patients taking a biosimilar took only that biosimilar, and about half of returning patients using a biosimilar had switched from the reference product.
Most physicians (72.8%) prescribed only the reference product compared with just 3.5% who prescribed only biosimilars. Of those who prescribed both, 61.4% had switched some patients from the reference product to a biosimilar.
A “Considerable Minority” of Patients Switched to a Biosimilar
The authors said the reasons for the slower adoption of infliximab biosimilars compared with the previous filgrastim biosimilar are unknown. However, they speculated that “patients and physicians may be more reluctant to switch from a working biologic regimen in a chronic setting than an acute one.”
However, they acknowledged that “a considerable minority of patients did switch between biologic and biosimilar versions in 2018,” and suggested switching could have been the result of cost reductions, such as lower patient co-pays or physician rebates.
Infliximab biosimilars will gain much greater traction in next several years, based on results from Europe, they suggested. “After 2 years, biosimilar infliximab garnered 13% of European market share, with subsequent uptake increasing steeply to 52% by 5 years.” In the United States, infliximab biosimilars have been available for less than 4 years. In December 2019, Amgen got FDA approval for its Avsola infliximab biosimilar, which launched in July 2020.
There are currently just 2 filgrastim biosimilars on the US market.
Another recent study on infliximab biosimilar use in Medicare beneficiaries similarly reported slow uptake but an increase in infliximab biosimilar use over time.
Chen AJ, Gascue L, Ribero R, Van Nuys K. Uptake of infliximab biosimilars among the Medicare population. JAMA Intern Med. Published online July 20, 2020. doi:10.1001/jamainternmed.2020.3188