Controversy over arthritis biosimilar listing
The first biosimilar to be sold in retail pharmacies has been listed on the PBS amid criticism from Australia’s peak rheumatology body.
Brenzys, an etanercept biosimilar for the treatment of several rheumatology conditions, was listed on April 1st with an “a-flagging”, which means pharmacists can substitute it for the originator biologic, Enbrel, without consulting the prescribing doctor.
Brenzys is the second rheumatology biosimilar to get a PBS listing, behind Inflectra (infliximab), which was a-flagged a year ago.
Dr Mona Marabani, chair of the Australian Rheumatology Association’s biosimilars working group, said the new listing was concerning because unlike Inflectra, a hospital-dispensed infusion product, Brenzys is a self-injected medication available at retail pharmacies.
“Pharmacists may stock only the originator or the biosimilar, which means there is potential for the patient to receive a different drug every month,” she said.
And yet multiple switching between biosimilars and their originator drugs is an “evidence-free zone”, she said.
Dr Marabani said responsibility for determining whether a biosimilar is interchangeable with its originator drug was quietly switched last year from the TGA to the PBAC, creating a conflict of interest.
“The funder is making the decision as to whether the drug is interchangeable, and not the regulator. My position is that the regulator should regulate and the funder should look at cost-effectiveness,” she said.
She said one PBAC criterion for determining interchangeability is “absence of proof” to suggest differences in safety and efficacy between a biosimilar and reference drug.
“This is clearly concerning as it reverses the onus of proof. Absence of evidence is not the same as evidence of absence,” she said.
“The powers that be keep asking rheumatologists what’s going to make us confident in prescribing biosimilars. What makes us confident is data. We recognise that biosimilars represent an opportunity. We are all for reducing the cost to the community. But there are data gaps at the moment; there are things we don’t know.”
Dr Marabani said the ‘a’ flagging of biosimilars is the “wrong mechanism”, adopted by only one other country in the world, Venezuela.
The Department of Health has launched a Biosimilar Awareness Initiative to address the lack of information surrounding biosimilars and boost confidence in their use. But a CPD accreditation program for biosimilars won’t be up and running until later this year.
Meanwhile MSD, which is marketing Brenzys in Australia, is pushing back against criticism from the Australian Rheumatology Association.
The company said it had consulted widely on the introduction of the biosimilar.
It said that in Europe, rheumatology biosimilars have been used for a number of years with no reports of enhanced immunogenicity or unexpected adverse events.
It noted that the pharmacy substitution process allows for prescriber and patient choice and is not automatic.
“For any individual prescription, a prescriber may choose not to permit brand substitution. If on the other hand, substitution has been permitted by the prescriber, the patient may choose which brand they wish to receive from the pharmacist,” the company noted.