The son of a small-town doctor in rural Texas, Dr. Thomas began his research in the 1950s at a hospital in Cooperstown, N.Y. At the time, there was little hope of survival for those with leukemia and other blood cancers.
The standard treatments — mainly crude chemotherapy to kill cancerous cells — were “fairly god-awful” and rarely drove the disease into remission, said Mark James Levis, a leukemia specialist at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University. But early bone marrow transplants had shown little promise. Dismayed by the procedure’s complexity, most experts considered such transplants a medical dead end.
With help from his colleagues, Dr. Thomas set out to prove otherwise. Today, bone marrow transplants are standard care for leukemia. The procedure also is used to treat lymphoma, multiple myeloma, a number of autoimmune diseases, aplastic anemia and myelofibrosis.
“This year’s Laureates paved the way for transplantation in man,” the Nobel Assembly at the Karolinska Institute in Sweden declared in 1990 when Dr. Thomas and Joseph E. Murray, who performed the first successful kidney transplant, received the Nobel in medicine. Their discoveries, the assembly noted, “are crucial for those tens of thousands of severely ill patients who either can be cured or be given a decent life when other treatment methods are without success.”
Dr. Thomas spent nearly his entire career trying to overcome the inherent difficulties of attempts to save lives by transferring tissue from one human into another.
In his case, that tissue was bone marrow, the spongy material in the center of bones where blood stem cells reside. Those stem cells produce red blood cells, white blood cells and blood platelets.
In leukemia, blood stem cells turn cancerous. Chemotherapy and radiation may kill the cancerous cells, but the treatments leave patients without any healthy cells to continue producing blood.
Doctors may introduce new bone marrow from a donor, but dangers abound. The patient’s body may reject the foreign marrow. Or, in the case of the serious condition known as graft-versus-host disease, the donor cells may attack the patient’s own organs.
In 1956, hoping to avoid such complications, Dr. Thomas conducted the first bone marrow transplant on a leukemia patient using donor cells from the patient’s identical twin.
A major breakthrough came when he showed that exhaustive matching techniques could vastly expand the possibilities of transplants, making them viable for people who are not closely related.