probably means that with 797 a longer treatment period is warranted to ensure the treatment effect stays
Yes - that would be my take. There is presumably some risk that the same effect that showed up in RA studies would show up here too.
The graveyard related to safety issues - I don't think it matters that this is a different indication than for the previous drugs. The safety issues have been all over the place - hard to know if they are class effects or (perhaps more likely) because most of the molecules were built off the same scaffold if I recall correctly.