Two people who received a groundbreaking cancer treatment developed at the University of Pennsylvania in 2010 now remain cancer-free, a signal that there could be a possible cure for leukemia.

Researchers first treated the patients in 2010 for chronic lymphocytic leukemia with CAR-T therapy, which uses the body’s own immune system to fight cancer, according to The Philadelphia Inquirer.

In a paper published in Nature on Wednesday, researchers reported that the two patients were still cancer-free and the cells that protected them against the lymphoma invaders were still present.

The treatment

When the treatment was first given in 2010, this sort of therapy “was way out there,” said Dr. Carl June, per The New York Times. “Now we can finally say the word ‘cure’ with CAR T cells,” he added.

  • Chimeric Antigen Receptors (CAR) T therapy genetically modified the body’s T-cells, which are the white blood cells that play a role in the body’s immune response to foreign particles, to attack cancer.
  • Although this treatment may work well for some and not for others, the results provide hope.

The patient

Doug Olson, a former scientist, was diagnosed with chronic lymphocytic leukemia, a type of blood cancer, in 1996 when he was 49. In 2010, he decided to enroll in the CAR-T study as a last resort.

  • A couple of weeks after first getting the treatment, Olson was sick for a week and hospitalized for three days, according to The Associated Press.
  • The very next week, his doctor sat him down and told them that they could not find a single cancer cell in his body. The other patient, Bill Ludwig, had similar results.

The unanswered

Whether cancer never returned, or the modified T-cells attached to any new cancer cells, is still unclear.

“It could be every last cell was gone in three weeks, or it could be they keep coming up like whack-a-moles … but get killed because (the CAR-T cells) are on patrol,” he said. “That aspect of how remission is maintained is very hard to study in a patient who doesn’t have leukemia,” said June.

Among those with cancer, about one-third to one-fifth go into remission with CAR-T therapy, too, the researchers said.

“The question is not only why some patients relapse or are resistant to therapy but why are some patients cured?” said Dr. John F. DiPersio, chief of the division of oncology at Washington University in St. Louis, who was not involved in the study, per the Times.