Rheumatologists must navigate patients through complex world of biosimilars

News that a second biosimilar has now been ‘a’ flagged in the absence of an adequate pharmacovigilance program means it is now down to rheumatologists to help their patients navigate the increasingly complex world of biosimilars, the ARA says.

On Friday the PBAC announced that they had decided to ‘a’ flag Brenzys and its originator biologic Enbrel for the purposes of substitution by a pharmacist at the point of dispensing.

In its notes from its July meeting the PBAC said that in forming its view on brand substitution, it had considered a range of factors:

  • Evidence presented in the SB4-G31-RA trial in treatment-naïve patients initiating on either Enbrel or Brenzys supported a finding that Brenzys has equivalent effectiveness and equivalent safety compared to Enbrel;
  • The key randomized clinical study in rheumatoid arthritis did not indicate differences in efficacy or safety of Brenzys compared with Enbrel;
  • The clinical data provided in the submission did not suggest there were any identified populations where the risks of using the biosimilar product in place of the reference biologic were disproportionately high;
  • In the SB4-G31-RA Phase III extension study, which included 52 weeks of additional data, including from a one-way switch from Enbrel to Brenzys, the clinical evidence suggested no difference in efficacy, safety or immunogenicity between the biosimilar and the reference biologic; and
  • The drug, etanercept, is not immunogenic per se, and anti-drug antibodies are rare. Switching between brands of etanercept is unlikely to change this.

However, speaking to the limbic chair of the ARA biosimilars working group Dr Mona Marabani, who has remained steadfast in her view that there is not enough evidence to support ‘a’ flagging, said there was no more evidence now about substitution, switching and extrapolation of indications than there was before.

“Most countries in Europe have laws AGAINST substitution. The EMIA, which Australia often follows in making these decisions, makes no findings on interchangeability… There is still no naming convention in Australia, which makes traceability a problem,” she said.

She noted that there was data from phase 1 and phase 3 studies which indicated Brenzys was safe and efficacious.

At this year’s EULAR annual conference in London a study looking at a single switch from Enbrel to Brenzys showed efficacy and no safety signals at 12 months.

“Enbrel does have a lot of data suggesting that the compound has very little immunogenicity and Brenzys appears similar in this regard,” Dr Marabani said.

“This may mean that the risk of loss of clinical effect or appearance of immune-mediated side effects is lower in these agents than with the monoclonal antibodies,” she said.

ARA remains disappointed

However Dr Marabani said the ARA was disappointed about the lack of commitment from the

government to fund a much needed enhanced surveillance and pharmacovigilance program.

“We believe that such monitoring is vital in order to fill the evidence gap,” she said.

“There is potential for patient confusion if substitution takes place at the retail pharmacy, where most dispensing will take place, with different syringes and delivery devices… education will be important here.”

Dr Marabani said the ARA made no recommendation about which drug to prescribe, but suggests that rheumatologists consider the options, decide what to prescribe (Enbrel or Brenzys) and ‘tick the box’, so that the patient receives the same medication every time.

“This is the reality of the situation, and it is now up to us as specialists to help our patients navigate this increasingly complicated environment in a way that maintains their safety and confidence.”

She noted that the Department of Human Services had given assurances that electronic submission of bDMARD applications would be possible by the end of the year, but there had been no news on progress, meaning the timeline was “unlikely to be met”.

Marketed by MSD in Australia Brenzys™ is the first biosimilar of Pfizer’s originator drug Enbrel™ and follows hot on the heels of the infliximab biosimilar Inflectra™ which received a PBS listing in December last year.

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