PEG MW

[PEGERON]

WHAT IS THE MW OF THE PEG USED IN BESREMI?

[hunter5582]

Are you referring to ropeginterferon alpha-2b

[PEGERON in reply to hunter5582]

YES

Also, is it a straight chain or branched PEG?

[EPguy]

I've posted on this general area. For Pegasys this report offers the MW:

accessdata.fda.gov/drugsatf...

"recombinant alfa-2a interferon (approximate molecular weight [MW] 20,000 daltons)...Peginterferon alfa-2a has an approximate molecular weight of 60,000 daltons"

so the Pegylation should be the diff at 40,000 daltons.

This label for Bes offers:

" The average molecular mass is approximately 60 kDa, of which the PEG moiety constitutes approximately 40 kDa "

ema.europa.eu/en/documents/...

So PEG and Bes are identical in MW, both the IFN molecule and weight of the peg. But Peg uses apha 2a while Bes uses alpha 2b.

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and here the peg portion of Bes is branched while it is attached at the IFN terminus. My guess is that means the peg internally is branched while its assembly with IFN is in series or chain:

" site-specific conjugation of a 40 kDa branched mPEG polymer...redesigned PEG moiety allow specific PEGylation to preferentially occur at the N-terminal proline"

pmc.ncbi.nlm.nih.gov/articl...

Bes big claim is having a single and consistent attachment point ("site-specific" as described in this report) vs PEG which may have more than one and the several may further differ in attachment location along the IFN-a. Single site is supposed to offer better results "as opposed to the 8–14 isomers of other PEGylated IFN alfa products" This might mean the peg is in series with the IFN in Bes but the assembly of the two in Pegasys has the pegylation branched off the IFN. Pegasys presumably also use a branched form of the pegylation portion as does Bes but I don't have a report on that.

There was also Peg-Intron, 2b, which I've not checked. It's off market.

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This is a discussion of pegylation:

healthunlocked.com/mpnvoice...

and comparing IFNA2A and IFNA2B:

healthunlocked.com/mpnvoice...

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Many other biologics are pegged as you likely are familiar, but I don't know more about those. One of my favs is Plegridy, pegylated IFN-Beta.