You wrote:The FDA told Mesoblast in the Type A meeting that they...

You wrote:

The FDA told Mesoblast in the Type A meeting that they would need more potency assay data before approving Ryoncil, and that if Mesoblast couldn't produce data from a potency assay that existed in the phase 3 trial that met the FDA criteria, then Mesoblast would need to conduct another trial.

As such, for the FDA to accept the resubmission.. Mesoblast must provide data from a potency assay that existed in the phase 3 trial. Or else the FDA would reject the resubmission and request that another trial be performed.

I agree with this essentially - yet you and I seem to have radically different conclusions otherwise.

I hold, as I think does southoz, whytee,docmcstuffins and I think the FDA themselves based on a statute and guidance related to interpretations of that statute that a BLA requires at least one adequate and well controlled trial.

I see pieces on analysis in what you write that suggests you get it, I saw a piece of analysis in what Reg wrote recently that suggests he got it too, but then you seem to not put the other pieces together.

My best guess as to why I get a different conclusion to yourself and Reg is you guys may not have as good an understanding of the possible potency assays components that conceivably could be in any potency assay Mesoblast offers the FDA.

More knowledge of either the history of what MSB and Silviu in particular have said on the specifics of the potency assay - that is at the level of the molecules tracked (because the molecules necessarily fit into pathways as cytokines or receptors of cytokines or transcription factors etc) would clarify things for you guys or just more general understanding of that level of detail - which is obtainable from reading things like MSB associated papers - there is a granted patent recently for pete's sake and there is writing by Aggarwahl and Pittenger from 2005 that is a core paper behind almost everything MSB does or says on potency assays when they are talking to scientists like at ODAC or to patent examiners.

If folk like stockrock and otherperspective and phaedrus simply combined together to ask Silviu what are the components of the new potency assay and how could it have been both there when the original ODAC meeting (prior to CRL 1) was done and its avaiable now then quite simply what is it?

Or if he can't tell why can't he tell?

I know MSB has a patent now. I missed, when I wasn't watching for a while that a patent application became a patent granted (with a reduced list of claims).

In the s ha r e caf e video on youtube from about 3 weeks ago Silviu is asked this question by the host pretty much and yet he doesn't really answer in my opinion he waffles on ... its the first question of only two asked by the host towards the end.


TNFR1 and IL2Ralpha are already public domain known potency assay components at molecular level. The first works pretty well in my opinion the second I am nowhere near so confident about but these things are very much public domain - there is really very little about them that can be hidden from sciencey types that can read the literature in my opinion.