"Pseudoprogression is only labeled as such if there is initial growth followed by a clinical response (either CR or PR - can also be SD, but that’s not going to drive commercial outcomes)."Yes, that is correct, however I'm talking about possible pseudoprogression and not confirmed pseudoprogression.
"Since pseudoprogression (initial growth that leads to CR/PR) rates are very low at 6% across roughly 4000 people (ICI + P3 T-VeC), it's very likely that initial growth in a tumor often leads to no response."
However, a further study, Talimogene Laherparepvec Improves Durable Response Rate in Patients With Advanced Melanoma, which you provided a link to and was the study without the addition of an ICI, found:
Just to reiterate, more than 50% of patients progressed before having a response which as you explained, is pseudoprogression. So, perhaps the addition of an ICI reduces the likelihood of pseudoprogression whereas the oncolytic virus (T-VEC) when used in monotherapy caused pseudoprogression in more than half of the patients treated with it; of the 295 patients treated with T-VEC 295, more than 148 patients displayed pseudoprogression.
(Incidentally, whilst not directly related to our discussion, I find it interesting they classified a 10.8% CR rate with T-VEC as high. It seems the bar is not very high? And despite only achieving a 10.8% CR rate, T-VEC was approved by the FDA for use. It shall be a very interesting comparison to see how Vaxinia fares when used against melanoma.)
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All of the best outcomes achieved for each patient in the P1 trial - every PD, SD, and PR. I find it strange that there are no iCPD, iSD, or iPR for any other patient."
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You have misunderstood me. I was discussing with James the iUPD rates in the Phase III trial that he was quoting, not the P1 CF33 trial."
Ah, ok, I did misunderstand the context of your comment however none the less, it does still appear only 4 patients were assessed using iRECIST therefore we cannot know if any of the PDs would have been iUPD or iCPD if they were assessed using iRECIST rather than RECIST 1.1.
Finally, in an earlier post you made the comment
"The dosing and response data from this phase 1 trial so far suggests that the optimum dosing regimen has been met,"
With today's announcement of the Bile Tract Cancer expansion opening, it would indeed seem they have settled on an optimum dosing regimen for that indication. I expect they will continue with the dose escalation cohorts in other indications because different cancer types may have different optimum dosing levels. With the opening of the Bile Tract Cancer expansion, it sets the clock ticking so to speak in terms of when we can expect results; allowing a couple of months to enrol and commence treatment of the 10 patients and 4 months because of the possibility of pseudoprogression, that brings us to a mid-October timeframe for a data cut so, we should have some answers by the end of the year if not sooner.
(20min delay)