My dad was also on Nexavar for about 18 months before it stopped working. Tried Sutent, but on the second round had chest pains, so doctor stopped treatment. Now getting ready to start Torisel, which is the newest drug (approved in May 07) for treatment of advanced RCC. Torisel is not taken orally, but given intraveneously once a week. I believe Torisel works in a similar fashion to Nexavar and Sutent, but in a different way. From what I've read, there have been good results with trials. Your dad may want to inquire about Torisel.