Sent you an email. Someone here already mentioned Poly-MVA, which I actually know something about as I used to be involved in research on that product and some other non-mainstream treatments that can actually be effective for some cancers.
Looks like you're getting some great advice here. Big thing (in addition to financial support) is to do your best to keep up a positive attitude and help your son to do so as well. It will boost his immune system and help him fight the disease, as well as keep him happier
Best of luck, you're in my prayers.