From my understanding, both reg3a and sST2 are good indicators...

From my understanding, both reg3a and sST2 are good indicators of damaged gut, thus it will be a good marker to see how a reduction is these markers, which form the basis of MAP, predict survival. It's definitely good to have more data to speak to the potency of our cells. Potency was the FDA voting question, we received 9:1

But the FDA is asking for consistency/reproducibility and critical quality attributes, by which we currently have TNFR1 expression on the MSCs. Maybe the FDA is asking for more than one marker, but they are definitely looking to see the level of TNFR1 expression to correlate with potency (both in vitro and in vivo).

For consistency/reproducibility, SI presented the slide where the expression of TNFR1 (CV/spread) from the NEW/IMPROVED method was much narrower compared to the OLD method (more variable/spread out).

This leaves us with most important issue: the critical quality attribute. Is TNFR1 alone sufficient? Can we convince the FDA that TNFR1 is the most important marker for potency of the cells compare to: 1) donor to donor variability 2) other markers (eg: IL6R) 3) extracellular vesicle expression etc...

Having said that, SI has announced that the FDA was satisfied with MSB's approach at addressing these issues. Therefore I am hopeful that we might get an Acc Approval for children under 12. I am definitely frustrated at the pace of progress, although I suspect the FDA is the one dragging its feet?




@mackinnon313 I think the MOA is more forgiving and often used as an excuse to try to delay approval. The issue that will stop approval is definitely CQA/QA/QC etc.. which fall under the CMC department at the FDA.