Certainly there are lots of cases of expensive long-term treatments being developed.
Do you have examples of situations where cures have been suppressed in favor of expensive long-term treatments? Especially in a competitive environment, where there were multiple players offering competing long-term treatments that were both aware of cures?
Preferably this would be something supported by leaked or court documents, but independent investigations would also be interesting. I understand this is a high burden of proof, but everything I've seen seems to indicate that this is an urban myth. I certainly couldn't find any specific cases in a cursory search.