Looking at upfront alone is short sighted. I'd rather them to partner with Genetech or NVS for half of the upfront than with those who don't have much experience in oncology.
Roche would make sense with their diagnostics and personalized medicine approach, however, Genentech/Roche doesn't seem to have a great history of giving the partner deal terms which are generous to the partner.
Why genentech and roche in particular? Both companies already have drugs for BC and Melanoma either on the market or in trials. Since CDX011 has already been tested for both those two indications, they are probably the quickest to market. Why wouldn't another pharma with unlimited resources albeit less exposure to oncology development that wants to have a drug for BC and Melanoma not be a better partner? Chances are that with Roche and NVS CDX011 would be buried behind TDM1 and Afinitor and CLDX would be stuck with a small upfront and a partnered drug that won't earn revenue for years and years.