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Wednesday, September 7, 2016

Biosimilar Interchangeability – The PBAC's consideration of Brenzys (etanercept)

By Sarah Matheson, Partner, and Ric Morgan, Special Counsel

We now know that the PBAC is prepared to have Brenzys, MSD's biosimilar version of etanercept, 'a-flagged' to Pfizer's as Enbrel.

It appears that the PBAC has continued with its unique position and allowed in-pharmacy substitution in the absence of evidence specifically addressing interchangeability.

The PBAC identifies six matters that it considered in deciding to 'a-flag'.  Of these, only two actually address issues beyond the assessment of whether Brenzys is safe and efficacious as a biosimilar product. 

The first of these relates to study of a "one-way switch from Enbrel to Brenzys".  As noted in our previous post,  such switching and interchangeability involve different risks.

The second is to say that:

"The drug, etanercept, is not immunogenic per se, and anti-drug antibodies are rare. Switching between brands of etanercept is unlikely to change this."

Whether this addresses the real concerns about the PBAC's approach is questionable. Because the PBAC does not refer to any studies or evidence on interchangeability, it appears that there are no studies on which it has relied.

It also suggests that the PBAC is conflating switching (on a single occasion) with interchangeability, as allowed by 'a-flagging'.

It seems that the PBAC is relying on prescriber control and patient choice to suggest that by allowing 'a-flagging' they are not really supporting full interchangeability. The PBAC states:

"…the substitution process allows for patient and prescriber choice and is not automatic. For any individual prescription, a prescriber may choose to not permit brand substitution. If substitution has been permitted by the prescriber, the patient may choose which brand they wish to receive from the pharmacist."

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