The treatment "has broad implications for multiple types of cancer," said lead author, Dr. Joshua Brody, director of the lymphoma immunotherapy program. "This method could also increase the success of other immunotherapies such as checkpoint blockade."

Researchers said some patients in the initial human trial went into full remission for months or even years.

Researchers at New York's Mount Sinai Hospital tested the treatment in 11 patients with lymphoma. Their results were successful enough to warrant another clinical trial in March on lymphoma patients as well as breast and head-and-neck cancer.

An experimental cancer "vaccine" showed promising results in a small clinical trial of patients with lymphoma, according to a study published Monday in the journal Nature Medicine.

They refer to it as a vaccine because it causes a person's immune system to fight the disease, though it's not preventive like the flu shot. In this case, the treatment teaches the body to recognize tumors and attack them.

Researchers created the treatment directly inside the tumor. To do this, they injected one tumor with a stimulant to recruit immune cells, treated the tumor with a low dose of radiation then injected it with a stimulant to activate immune cells. These activated immune cells then travel throughout the body, killing tumors wherever they find them.

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In three of the patients, the treatment shrunk not only the tumor that was treated but also other ones throughout the body, putting these patients into remission.

"It's really promising, and the fact you get not only responses in treated areas, but areas outside the field [of treatment with radiation] is really significant," said Dr. Silvia Formenti, chairwoman of radiation oncology at Weill Cornell Medicine and NewYork-Presbyterian, who was not involved in the study and is working on a similar treatment.

While promising, the effect was observed in only three people and will need to be tested in larger trials before even going before the Food and Drug Administration for review.

Dr. Eric Jacobsen, clinical director of the Dana-Farber Cancer Institute's lymphoma program, said the results are exciting but cautioned more research needs to be done. Jacobsen was not involved in the study.

"It's definitely proof of concept, but larger studies are definitely needed and additional strategies to try to get more than three out of 11 patients to respond," said Jacobsen, who is also developing a lymphoma vaccine, though with a slightly different approach.

Researchers for decades have tried but failed to create cancer vaccines. New research on immunotherapy, or training a person's immune system to fight disease, has reinvigorated their efforts.

The vaccine activates dendritic cells, which are responsible for initiating immune responses. These cells then instruct T-cells to attack tumors in a person's body, like generals instructing soldiers how to fight.

"Generals don't really fight wars, they make the plans," Brody said.

The research was funded by The Damon Runyon Cancer Research Foundation, the Cancer Research Institute and Merck. Celldex and Oncovir provided the materials for the clinical trial and the lab work.

Correction: This story was revised to correct a quote from Dr. Formenti. She said "treated," not "three."

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