Well a quick googling showed that they are doing studies with methadone and as it is an old drug, it isn't even protected by patents and it is being sold. You can even start your own company and sell methadone if you feel like it.
They are actually producing literally tons of methadone annually.
Edit:
"Therefore, the first experiences with the treatment are not considered scientific proof of the supportive effect of methadone in chemotherapy yet - according to the rules of drug licensing."
http://www.dw.com/en/fighting-cancer-with-methadone-making-chemotherapy-more-powerful/a-19482264
Sure it is being sold, as it is a replacement therapie for heroin addiction. The fact, that it is useful in the fight against cancer, was researched about 10 years ago from the fraunhofer institute in germany. The pharma industry just held it back because it was to cheap. Methadone helps the chemo radiation to irrupt more deeply into the cancer cells and destroys them therefore more easy.
There are many cases in which methadon made the unbelivable real and cured the cancer completely.
Are you aware that you are acting very similarly to the individual caricatured in this steemit article?
Methadone does not help to destroy cancer in conjunction with standard therapy. Methadone might help to kill off glioma or glioblastoma cancer (brain tumor) cells in conjunction with standard therapy. And patients don't get exactly cured. They might live longer which is of course a very good argument for using this cheap drug and make the pharma companies cut their profits.
Saying Methadone is not the one-for-all cure of cancer ;-)
my god! help us all!!!