FDA punts on interchangeability in biosimilar rule

If there is anything that can be concluded from the FDA’s draft biosimilar guidance, it is that the agency will not be sanctioning direct substitution of lookalike biologicals anytime soon. Whilst the regulator said it has the power to declare a competitor as “interchangeable,” it immediately threw water on its ability to do so, at least for now.

The “stepwise” procedure the agency laid out for bringing a biosimilar to market will include effectiveness studies in many cases, which will drive up the costs of bringing a product to market, when compared to the pharmacokinetic or pharmacodynamic studies that might be required when a drug is declared interchangeable. Whilst this may be a disappointment to many working in the space, a commercial critical mass is building. With patent expiries in the next two years putting $11bn in biologicals sales at risk, the target is huge, and the establishment of a designated approval pathway clears away some lingering doubts about the viability of generic competition (Patent storm hits in 2012, February 8, 2012).

Pharmacist substitution

With generic competition thought to be a source of major health care savings, Congress authorised the FDA to develop a biosimilar approval pathway as part of health care reform legislation in 2010.

As therapeutic options with complex development and manufacturing requirements, and treating rare conditions, biologicals tend to be more expensive than their small molecule counterparts: Soliris, an antibody, costs more than $400,000 a year. Thus payers and government programmes are eager for biosilimar products that can start to chisel away at the higher prices demanded by innovator companies.

Achieving “interchangeability” under the law is likely the hope of many. Essentially, it would allow direct substitution of a biosimilar for the original product, declaration of which would shorten the approval pathway and likely provide a greater commercial edge, as they would be directly substitutable at the pharmacy.

Agency officials had telegraphed that interchangeability would be a tough standard to meet. Janet Woodcock, director of the FDA Centre for Drug Evaluation and Research, stated in a New England Journal of Medicine commentary that a biosimilar will only be considered interchangeable if it is expected to produce the same clinical result in any patient and that the risk of alternating or switching is no greater than continuing to use the original biological product – essentially copying the statutory language (US biosimilar rules due by year end, November 23, 2011).

Scientific challenge

The draft document released yesterday – and now open for public comment - acknowledges the FDA’s authority to determine interchangeability in an original application, but states that “it would be difficult as a scientific matter to establish” in an original application “given the statutory standard for interchangeability and the sequential nature of that assessment.”

“FDA is continuing to consider the type of information sufficient to enable FDA to determine that a biological product is interchangeable with the reference product,” the draft documents state.

Even if interchangeability is not achieved with the first cohort of applicants, the market is becoming too attractive to ignore. A number of transactions last year have shown big pharma’s growing appetite for biosimilars (Momenta steadies the ship with Baxter biosimilar deal, December 23, 2011).

With clarity on the regulations, it will no doubt help those companies considering similar deals or initiating preclinical work on lookalike drugs whether those activities will pay off. New players will want to get in this game.

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