Avastin plus interferon for xp11.2 translocational RCC (9-year-old son)

I posted at SP, but want to ask here and see if anyone has experience with Avastin plus interferon. 


Profile: 9-year-old boy dx in March, 2013, xp11.2 translocation RCC. Left kidney removed with 20 more tumors in lymph nodes nearby. There are 5 clusters of tumors in neck, chest, abdoman, all in lymph nodes. Started Sutent on 12.5 mg for two months, no work. Increased to 25mg, works for 4 weeks. For another 8 weeks, Sutent stopped working.

We were given about 10 different options, including mTOR, immunotherapy, chemo. Basically there is no data which one will work. Dr doesn't have a strong feeling with either of the options. We just have to try. His oncologist sounds like want to try Avastin plus Interferon. I know interferon is very hard to tolerate. I'm heartbroken thinking about we have to try different toxic in his tiny body. He is just such an innocent child and he told me he doesn't care the scan isn't good. He has no side effect AT ALL from 5 cycles of Sutent, (25mg, he weighs 55 lb) going to school and doing sports. 

Any input is appreciated!