Look this is a refractory population for which there isn't any options out there that wood confound the earlier Pfs difference. Plus the median OS is short most these patients probably go to hospice. We know Pfs is correlated with OS and can be considered as a surrogate endpoint. Now if you tell me this is first line her2+ then I would be impressed.
I don't buy it until cldx shows there is no bias in the process of subset ting.