It was late 1997 and Doug Jensen, 71, of Canby, Ore., thought he’d developed a particularly stubborn cold. But his symptoms dragged on and “kept getting worse,” he said.

Then Jensen got the devastating news: Blood tests confirmed he had chronic myelogenous leukemia (CML), a deadly blood cancer.

In 1997, average life expectancy for CML patients “was about four to six, maybe seven years,” according to Dr. Brian Druker, a cancer researcher at Howard Hughes Medical Institute and the Oregon Health and Science University Cancer Institute, in nearby Portland.