Hi and sorry to hear about your wife. My husband has stage IV, diagnosed a year ago.
I am not sure if your message meant that your wife has only received oxaliplatin and Avastin? My husband's first regime was Eloxatin (oxaliplatin) + Xeloda (capesitabine), then they added Avastin. When Eloxatin was dropped, Xeloda and Avastin alone did not keep the situation stable, so the regime was changed to Erbitux + Xeloda + Camptosar (irinotecan) and it is working well. Has your wife received Camptosar? Camptosar can be given with both Avastin and Erbitux (or Vectibix which is similar to Erbitux just made by another company).
However, please check, I think I read about research that suggests that the KRAS mutation may not be 100% proof Erbitux will not work, it may still work for some patients despite the mutation. I am not sure if insurance covers it though in such case.
Other than that there are not currently many standard options but like someone else said, clinical trials may offer something valuable to your wife. Also some non-standard use of chemo, like Sorafenib (Nexavar), Gemcitabine, Cisplatin usually used for certain types of kidney or liver cancers might be used but your wife's doctors would naturally know a lot more about what might be sensible to test that as they are familiar with her case. Many of these non-standard uses are currently tested in clinical trials but as the medicine itself is approved maybe thay can be used for colorectal cancers even though they are not meant for it originally.
All the best, Mousey