The underlying biosimilarity standard is the same for both, Dr. Peng said, but interchangeability has a “statutory requirement” that a manufacturer must show that, if you switch, “you won’t show more increased risk or diminished efficacy.” She added that this is often done by providing the same information provided for biosimilar designation.
Dr. Schanberg said the distinction is not clear. “I think it causes confusion for consumers—certainly it is for prescribers—about whether really the interchangeables are of a higher quality, which I know you specifically say they aren’t. But it certainly does suggest that to the community.”
Dr. Peng said she hoped that with the FDA’s recently revised guidance, people will “know that the underlying standard is the same.”
Another audience member noted that the lack of biosimilars for adalimumab that are approved for pediatric uveitis “causes us many headaches.” Such omissions in indications typically arise from issues of exclusivity, Dr. Peng said.
Michael Shishov, MD, MPH, a pediatric rheumatologist in Phoenix, said he was “a little confused about how these conditions are chosen” for approval through extrapolation analysis. For example, he noted, pediatric oligoJIA, a common condition, has no FDA approvals.
In general, Dr. Belen said, decisions on extrapolation studies are made based on disease process, pathophysiology and how well they can be replicated in a pediatric population. Pediatric studies can be difficult to complete, in part due to enrollment challenges.
Jessica Perfetto, MD, a pediatric rheumatologist at NYU Langone in New York City, asked whether the same commercially available assays used for reference drugs can be used to assess drug levels and anti-drug antibodies.
“Given that the active ingredient is the same, you would expect that you would be able to use the same assays, but I don’t know the answer to that for sure,” Dr. Peng responded.
A pediatric rheumatologist from Italy expressed frustration that there is no lyophilized powder formulation for etanercept, even though this is the only formulation that can be used for pediatric patients less than 32 kg. Dr. Peng said that the FDA does not mandate what formulations are developed.
A pediatric rheumatologist from Toronto asked about the DRESS safely labeling.
“Detection of these reactions is quite challenging,” he said. “I’m wondering why the agencies chose to use DRESS as the terminology for the warning, because most of these reactions do not look like a classical DRESS that we know from other medications. And I’m wondering if there’s more guidance that could be provided to clinicians.”
