Despite State-to-State differences, in general US pharmacies can only give a patient a biosimilar in place of a reference drug if granted permission to do so by the prescribing physician.
In contrast, an interchangeable biosimilar is one that can be substituted without the intervention of the healthcare provider.
The US FDA can designate a biosimilar as interchangeable if a sponsor can prove it is “expected to produce the same clinical result as the reference product in any given patient” and that switching between the two is safe.
The difficulty for biopharmaceutical companies seeking this designation is that the Agency has not defined how they must generate such proof.
The FDA’s promise to publish interchangeability guidance this year – along with documents detailing how biosimilars should be labelled and the statistical approaches sponsors can use to prove biosimilarity – was welcomed by Sandoz.
The Novartis division told us "The interchangeability designation is a core component of the BPCIA. Therefore getting clarity, in the form of guidelines, is important to industry as we seek to introduce biosimilar medicines to the US market which will be of benefit to HCPs, patients and payors."
As recently as last April some companies suggested the FDA was still years away from interchangeability guidelines.
For example Diem Nguyen, Pfizer’s Regional President of Global Established Pharma, told attendees at Goldman Sachs' Biosimilars Conference that: “The FDA has been falling short in terms of how they define interchangeability at this point.”
She predicted that: “the FDA is going to be cautious and look at it on the data-by-data, asset-by-asset basis today whether an actual medicine becomes interchangeable or not.”
The major argument used by supporters of the Patient Protection and Affordable Care Act (PPAC Act), which became law in 2010, was that would reduce public healthcare spending.
Sandoz was the first to use the approval pathway.
The Swiss firm won US FDA approval for Zarxio (filgrastim-sndz) last March and was launched in September at a 15% discount to the reference product, Amgen’s white blood cell booster Neupogen (filgrastim).
Discounts and competition
Zarxio's lower price will likely cut healthcare spending.
However, the full impact of the BPCI will only be seen after the FDA decides on its interchangeability requirements according to Francis Megerlin from the Berkeley Center for Health Technology.
Megerlin - who authored an an oft-cited paper on the development of the US biosimilars market - told us “Patients treated with interchangeable products are not captive of a given brand. As a consequence, and according to states law that govern substitution, there could be a long-lasting competition for chronic treatments."
He also suggested interchangeable biosimilars may provide insurers with the opportunity to drive down prices.
“Insurers have an interest to enter and negotiate prices in the most competitive corridor, which would be defined according to the number of products competing, and by state laws that govern substitution.”