Now that the Food and Drug Administration has approved Inflectra as the first biosimilar version of the anti–tumor necrosis factor-alpha agent Remicade, rheumatologists and patient advocacy groups are taking stock of how it may be used in practice, and what the future holds for biosimilar drugs, with so many questions still unanswered regarding price, substitution, and safety.
Inflectra, approved in early April and given the generic name of infliximab-dyyb under the FDA’s nomenclature for biosimilar products, will have the same indications as Remicade. The agency extrapolated the clinical trial data that Inflectra’s South Korea–based manufacturer, Celltrion, submitted for rheumatoid arthritis and ankylosing spondylitis to all other indications for which Remicade is approved.
It’s currently unclear how the FDA will note which clinical data in Inflectra’s labeling come from Inflectra and which from Remicade, and the same concerns lie with future biosimilar approvals if their results are extrapolated to indications not tested to show biosimilarity in clinical trials.
It’s concerning to rheumatologists and the patients who will be using them that biosimilars such as Inflectra are not subject to the same pivotal trial experience as the reference biologics on which they are based, according to Dr. Jonathan Krant, section chief of rheumatology for Adirondack Health Systems in Saranac Lake, N.Y., and medical director for CreakyJoints, a community of patients with arthritis and caregivers, and its larger parent nonprofit advocacy organization, the Global Healthy Living Foundation (GHLF).
While the unique regulatory requirements in the biosimilar approval pathway reduce development costs and could potentially make Inflectra’s average wholesale price 30% less than Remicade – as was the case when Inflectra was first on the market in Europe – it’s not known how reduced costs may affect the safety of biosimilars.
“It worries all of us that manufacturers may cut corners to manage the cost constraints imposed by managed care,” Dr. Krant said in an interview.
Given that U.S. rheumatologists don’t have experience with biosimilars, Dr. Krant is anticipating some push back. “I think some physicians are going to fight back and won’t want to prescribe them, even if mandated, because of concerns regarding patient safety,” he said.
In a written statement, Dr. Joan Von Feldt, president of the American College of Rheumatology, welcomed the potential benefits on access to care that cost-saving biosimilars may bring to the U.S. health care system, but also said that “the safety of our patients remains our highest priority. As such, we encourage the FDA to continue to apply distinct names for future biosimilars, and to maximize clarity in the labeling of biosimilars, specifically with respect to their interchangeable status and the origins (reference drug versus biosimilar) of clinical data upon which FDA approval is based.”
Inflectra met the FDA’s “very similar” criteria to be approved as a biosimilar by showing it has no clinically meaningful differences in terms of safety and effectiveness from Remicade, the agency said. According to FDA regulations, biosimilar products can have only minor differences in clinically inactive components and must have the same mechanism(s) of action (to the extent that it is known) and route(s) of administration, dosage form(s), and strength(s) as the reference product and can be approved only for the indication(s) and condition(s) of use that have been approved for the reference product.
However, it may not hold true that Inflectra will have the same efficacy and safety for all indications that Remicade had due to potential differences in the mechanism of action through which Remicade exerts its effect across indications, which in this case may apply to the indications for Crohn’s disease and ulcerative colitis.
Health Canada chose not to extrapolate the indications for Inflectra (known as Remsima in Canada) to Crohn’s disease and ulcerative colitis because of “observed differences in the level of afucosylation, Fc-gammaRIIIa receptor binding, and some in vitro antibody-dependent cell-mediated cytotoxicity (ADCC) assays” that could not rule out the possibility that Inflectra and Remicade differ in their ability to induce ADCC. Unlike the other indications for Remicade, Health Canada said “ADCC cannot be ruled out as a mechanism of action in the inflammatory bowel diseases. This position is supported by the observation that certolizumab pegol, another anti-TNF [anti–tumor necrosis factor] that lacks the ability to induce ADCC, displays only marginal efficacy in Crohn’s patients, compared with other anti-TNFs, namely infliximab.”
Other organizations suggest that extrapolation of indications is only appropriate when it is benefiting the patient to the greatest extent possible.
“GHLF is okay with extrapolation of indication unless the mechanism of action for the therapy is either scientifically or therapeutically outdated,” Stephen Marmaras, state and national advocacy manager for the GHLF, said in an interview. “Patients are okay with extrapolating data in order to expedite the approval process as long as you are extrapolating to best in class therapy for a particular indication. What [the GHLF is] saying is we want biosimilars to be an improvement on what we have, not the lowest common denominator. We shouldn’t be extrapolating indications data from products that aren’t considered to be the best product for that indication.”