WASHINGTON – Data from the first randomized trial of switching from an originator biologic to a biosimilar of the originator indicate that the infliximab biosimilar Remsima is no different from the infliximab originator Remicade in the rate of disease worsening over 1 year across a combination of all its approved indications.
The outcomes of the Norwegian, double-blind, noninferiority trial, called NOR-SWITCH, indicate similar rates of disease worsening across patients switched to Remsima and those who stayed on Remicade. However, exploratory group analyses conducted on the different disease subgroups in the trial (Crohn’s disease, ulcerative colitis, spondyloarthritis, rheumatoid arthritis, psoriasis, and psoriatic arthritis) showed a potentially concerning level of disease worsening among Crohn’s disease patients on Remsima with a confidence interval that nearly fell entirely within the range favoring Remicade.
In the United States, Remsima, also known as CT-P13, is marketed by Pfizer as Inflectra.
Dr. Inge C. Olsen (left) and Dr. Guro L. Goll
The trial randomized 482 patients who were on stable treatment with Remicade for at least 6 months for any of the six indications for which Remicade and Remsima are approved to either stay on Remicade or switch to Remsima with the same dosing regimen for 52 weeks. Overall, patients had a mean age of about 48 years and 36%-41% were female. They had a mean disease duration of about 17 years and had been taking Remicade for a mean of nearly 7 years.
The primary endpoint was disease worsening during follow-up, according to worsening in disease-specific composite measures and/or a consensus between an investigator and a patient that led to a major change in treatment. The investigators made an assumption of 30% disease worsening across all the indications for the trial’s power calculation, based on available literature and observational data.
Disease worsening occurred in 26.2% of patients who stayed on Remicade and 29.6% of patients who switched to Remsima, based on a per-protocol analysis of 202 Remicade and 206 Remsima patients. The 95% confidence interval of the adjusted treatment difference of –4.4% was –12.7% to 3.9%, which was within the pre-specified noninferiority margin of 15%.
Exploratory subgroup analyses of the different disease subgroups showed no statistically significant differences between the two treatments in disease worsening. However, in Crohn’s disease patients, who formed the largest subgroup in the study at 155 patients, the adjusted treatment difference was –14.3% (21.2% with disease worsening for Remicade and 36.5% for Remsima) with a 95% CI of –29.3% to 0.7%.
It’s difficult to discern whether the 95% confidence interval seen in the Crohn’s disease subgroup is a part of the natural variation one would expect to see in a subgroup analysis of different diseases or if there might be a true signal for disease worsening in the Crohn’s disease patients who took Remsima. “The problem is that it’s in the largest subgroup that has no other data. If this had been in rheumatoid arthritis, that would be different,” coauthor Inge C. Olsen, PhD, a biostatistician at Diakonhjemmet Hospital, said in an interview. “All the registry trials were done in RA and spondyloarthritis patients. ... That’s an issue, but with regards to the [NOR-SWITCH] study, it’s very clear that you have no power to show anything in the subgroup analysis, and they are exploratory analyses and are not answering any hypothesis.” Currently, there are no plans to follow up on these results in another study, he said.
Other issues that the NOR-SWITCH study does not answer are the outcomes of switching back and forth between Remicade and Remsima, switching from one infliximab biosimilar to another infliximab biosimilar, and switching from other originator biologics to their biosimilars.
“Is that feasible? Is that safe? Will it retain efficacy? We don’t know. There’s a real need for those studies to be done,” Dr. Goll said.
In Norway, the remaining patients who had not switched yet from Remicade to Remsima are now doing so based on the trial’s results, Dr. Goll said. The cost of Remsima in Norway was about 75% less than Remicade in 2015 and about 60% less in 2016, she noted.
It’s still an open question what the results of the NOR-SWITCH trial might indicate for how clinicians in the United States will use Inflectra and other biosimilars, according to John J. Cush, MD, professor of medicine and rheumatology at Baylor University, Dallas.
“I think the real problem here is that it’s nice to know that [CT-P13] wasn’t inferior, but when you get into the weeds and you look at the details, those of us who may not have a lot of certainty about this might worry about this, especially when there are three new biosimilars approved in the United States: Amjevita, which is an adalimumab biosimilar; Erelzi, which is an etanercept biosimilar; and Inflectra’s about to be launched as an infliximab biosimilar,” Dr. Cush said during a session reviewing selected abstracts from the meeting. “When this NOR-SWITCH study was done in Norway, it’s a 70% savings over the original product. The new ones being introduced over here [in the United States] start at about 15%. I’m less motivated with that degree of savings to want to take some chances on my patients. So we need a little bit more certainty; we need to feel better about the cost savings to patients and health care overall. Confidence in biosimilars is what’s going to sell biosimilars. We’re a long way from confidence still.”
NOR-SWITCH was funded by the Norwegian government. Some of the investigators disclosed relationships with Pfizer and/or Celltrion, which separately market CT-P13 in different parts of the world.