I think you might be looking at this in a linear fashion.
The trial is not actually really a trial at all. It is more like a series of case studies.
They tested the DEP doc in a few patients with prostate and lung cancer. In the absence of an empirical counter-factual (a control group) the strength of the results are in the eye of the beholder.
But having seen the results from these patients SPL have decided to try their luck in other cancer tumours and with other drug combinations.
This all needs plotting out. New investigators at other centres are recruited.
It’s all highly exploratory; getting a better handle on which tumour (with or without another drug) to target. The “trial” where something is confirmed (or not) will come down the track.
So a bit of non-answer to question – why is this trial taking so long – answer – well its not really a trial at all.
Which comes back a little to your premise of obvious and substantial benefit.
Perhaps think of it like fishing.
You stumble on a hot spot where there are obvious and substantial fish numbers. Have you ever heard anyone in the boat say … “I know what why don’t we pull anchor and move a few hundred meters and see if the fish are biting even stronger there”.
Its pure PR spin thinking you can get a “obvious and substantial” efficacy claim out of a P1 cancer trial.
