(i'm not that familiar with rcc or onc area in general so please correct me, but my understanding is they likely need good PFS data to make it attractive to a partner as RR alone doesn't mean much - and I'm not sure just how much RR correlates to PFS in this indication)
The general rule I use is that the closer in time the two measurements the more correlation between them:
b) A disease with an average time to progression of 18 months - I'd suspect a weaker correlation to RR.
Note that IMO survival suffers from 2 weakenings of the correlation to RR - 1) death is further separated in time from Response than is progression, 2) death is a different kind of endpoint.
Given that rcc median pfs times are on the order of 3 to 6 months I'd expect a fairly strong correlation between rr and pfs. FWIW.
I think Zymo should really have IL-21 riding along the DNDN wave. Sipuleucel-T together with an immuno boost using IL-21 might have a chance to cure prostate cancer based on the MOA.