Liver mets.

Not the same as your sister, but I was diagnosed in April 2016 with bone mets. I had Taxol, then Letrozole and Herceptin/Perjeta every three weeks. Found out in January this year that a few small liver mets have appeared so my oncologist has kept me on Letrozole but replaced the Herceptin/Perjeta with Kadcyla. I've only had two rounds of this drug so too early to tell its effectiveness for me but I have read of plenty of women for whom it has worked well. Unfortunately it is the nature of this disease that all drugs seem to have a limited life in which they are effective and the body learns to work around it. The good news is that there are a number of options that oncologists can choose from. It's never nice to receive negative scan results but your sister is lucky she has you for support.