Keytruda, pembrolizumab, (what he probably received) can only do so much. If it was in his GI tract it was also elsewhere in multiple places. The PD-L1 drugs at this point have more than 400k patients treated, with decent efficacy. I'm sorry for your loss. If his melanoma had metastasized to his GI tract it was too late for anything except palliative care.
This drug has been used in a huge number of patients for more than 11 years; the next gen of drugs is currently being used. I'm sorry for my curt style of writing, but - people like your father have helped pave the way for that next generation of drugs by constraining clinical trial designs.
Nivumolab was the drug administered in adjuvant setting. Maybe you are right that 400k patient with decent efficacy - however pegged chances are about 70-80% and not 100. So my point is can there be a better test bench to try and inch closer to a better efficacy?
For example - if hela cells can be used for trials — can there be the cultured tissue be used instead of mice as day 1?
Also curious — how did the scientist decide on using a specific cell/protein to be used for checking if this is producing results. Is it a hunch or science ?