'Game-changer' cancer drug celebrates 20 years. Gleevec turned a death sentence into a chronic disease for many.

The fact that it's a long-term therapy means drug companies can make a lot of money, even on relatively rare diseases, said Dr. George Demetri, director of the Sarcoma Center at Dana-Farber Cancer Institute in Boston.

'Game-changer' cancer drug celebrates 20 years. Gleevec turned a death sentence into a chronic disease for many.