Since the drug is so new I'm not sure that anyone really knows how long to stay on it but I'll share with you my experience. Like your husband, I started out my first experimental treatment cycle (28 days on/14 days off) with the maximum dosage--50mg/day. We had fantastic results just after the first treatment--a 34% reduction in tumor size. By the way, this tumor was on my liver but did originate in my left kidney which was removed as a first defense. The second treatment cycle was also at the high dosage and resulted in no metabolic activity (the tumor was "dead"). The remaining treatments (I had a total of six) were at a lower dosage (37.5 mg/day) and 3 weeks in between. The entire time I was on the experimental program as Sutent was not FDA approved until my last treatment cycle. I was my doctor's first full response patient. We (the doctor, me and my wife) made the decsion to go off the drug to see what would happen. My thinking was that the drug had done its job and the upside to the treatments no longer justified the side effects. It was worth the risk and we would all learn something. I had my first scan after being off the drug for 3 months and no signs of the cancer. I had my six month scan just yesterday and will meet with my doctor on Friday. I feel good and we are confident. Since this drug is so new I don't think we (including my doctor) knows what the future will bring but if I pass the six month test we will feel good since my cancer originally returned just 5 months after they removed my kidney. Regarding my response to the drug: I think what really helped me was that we caught the re-occurance on my liver when the tumor was small and this may have attributed to my quick response. However, my doctor reported to me that he had had similar responses to patients with larger tumors, just not the quick full response that I saw.
Good luck to you and your husband and please don't hesitate to contact me if you have additional questions---I probably missed something.