Exactly, both CTC levels and tumor sizes are measu

Exactly, both CTC levels and tumor sizes are measurable and likely can be tied to the primary endpoint of progressive free survival (PFS) and thus qualify as a surrogate endpoints (based on the FDA criteria). While he hasn't stated the CTC will serve this purpose, if you listen to RPs comments when he is talking about testing these levels, IMO it is clear why they are taking them and what purpose they will serve. I took this read from him going back as far as NCXV and seemed even more evident in the latest LD Micro video.

While none of us exactly know, it seems this new CTC test is linked to the TNBC delay. NP has mentioned it in some interviews about RP using his connections (likely Dr. Cristofanilli.....the father of CTCs and others) to get the tests setup and all the work required to do so. With this length of delay, I'm guessing they had to validate to the FDA that CTC levels can be tested and are linked to tumor size and ultimately PFS.

Trding provided a great list of drugs approved based on surrogate endpoints. One thing I found while researching that criticized surrogate endpoints serving as approval is many of the follow-up stats / confirmatory trials did not translate or correlate to primary endpoints compared to drugs who completed trials before approval. The key here is ensuring that the surrogate endpoints are proven or very strong possibility to result in the primary endpoint (or the FDA rejecting approval for those who fail to prove or meet the PE criteria).

As far as RPs quote that misiu mentions, it was in context to the dose escalation phase and along the lines of: "We don't expect any issues with the 700 mg dose, but it is best to do it slow, do it safe and do it right by the patient. The technology is beautiful, we just don't need to fail the technology."

I have a lot of speculation in all of my above statements, but in my mind much of this is all linked to ensuring the test is 100% irrefutable as they fully expect the results to make worldwide news with their cancer results.

Here is a couple articles about surrogate endpoints used for AA for your reading pleasure:

https://www.healthaffairs.org/doi/10.1377/hlthaff.24.1.67

https://www.healthnewsreview.org/toolkit/tips...ole-story/

Please do your own due diligence. All my posts and comments are not to be considered investment advice.