As far as I understand, the main reason for this is that you would need to invest a billion dollar. You might have success with that but you also may not and th

As far as I understand, the main reason for this is that you would need to invest a billion dollar. You might have success with that but you also may not and then there a lot of other nice things you can do with a billion dollar. Governmental research projects have the tendency to go on even after everyone knows that they will fail, so money would be saved by doing them in the private sector where investors stop a failed project sooner. Unfortunately, if the backbone of the therapy has been developed in the 60s and 70s most patents have run out so there is nothing that would return most investments. The only one I could imagine doing this would be a private philantropist like the Gates Foundation.