Collaborative discoveries by stem cell researchers from the University of California-San Diego, the Dana-Farber Cancer Institute, the Mayo Clinic and a San Diego pharmaceutical company, TargeGen, moved the drug into clinical trials.

A study led by Dr. Catriona Jamieson, an assistant professor of medicine at the UCSD, found an inhibitor that can stop the over-proliferation of blood cells that result in problems with blood clotting, heart attacks and, in some cases, leukemia.

"As a clinician, I asked myself who is going to get this disease, and what can we do to stop its progression, instead of waiting until it evolves into a deadly cancer?" said Jamieson. "This project has been so extraordinary, because a small pharmaceutical company took a big chance on a rare disease."

The drug is currently being tested in human clinical trials at the UCSD's School of Medicine, the Mayo Clinic, the M.D. Anderson Cancer Center, the University of Michigan and at Stanford and Harvard Universities.

The research is reported in the journal Cancer Cell.