T-cells on the attack

"By creating 'armies' of T-cells that are augmented to find and kill cancer cells, we are aiming to develop a new generation of cancer treatments that can have better results and far fewer side effects for patients than current chemotherapy drugs or radiation treatment."

Ice crystals like powdered sugar audibly crunch as Dr. Cassian Yee pulls a long steel box out of a subzero freezer. Wearing bulky blue gloves to protect his hands, he gently extracts from the box a vial the size of a chess piece. A patient's precious T-cells are frozen inside, cells that may halt her advanced skin cancer.

Yee is on the cutting edge of a field known as adoptive immunotherapy. It's one of many unexpected breakthroughs to emerge from the bone-marrow transplantation treatments pioneered by the Hutchinson Center's Dr. E. Donnall Thomas to cure leukemia and other blood cancers.

By extracting rare cancer-fighting T-cells from the blood, multiplying them in the lab, and transplanting them back into the body, Yee and his colleagues are using adoptive immunotherapy to harness the power of the immune system to seek and destroy solid tumor cells.

"By creating 'armies' of T-cells that are augmented to find and kill cancer cells, we are aiming to develop a new generation of cancer treatments that can have better results and far fewer side effects for patients than current chemotherapy drugs or radiation treatments," Yee said.

His research was among the first to show that adoptive T-cell therapy holds great promise for treating melanoma, a potentially fatal form of skin cancer.

He is also optimistic that he can develop the therapy to treat women with advanced ovarian cancer. In recognition of the potential for his research, Yee was rewarded with a prestigious grant from the Burroughs Wellcome Fund to refine the therapy and improve its tumor-fighting ability.

While his success with melanoma has been a major advance in T-cell therapy, Yee is the first to acknowledge that, like the long games of chess he plays with his son, perfecting the treatment will be an incremental process. Dr. Cassian Yee and son"I tell my son, Nathaniel, that in a slow chess game he must stay focused and that every move on the board can affect the outcome," Yee said. "This is how I view the development of T-cell therapy. We are making step-by-step advances that take time, but our progress is steadily improving a treatment that could save many lives."

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An army of cloned T-cells goes on the attack, and wins

When Dr. Cassian Yee announced in June that the late-stage melanoma of one of his patients had gone into long-term remission, the news quickly spread throughout the world.

Yee and colleagues used a novel approach to stop the man's stage 4 melanoma: his own cloned T-cells. Yee was quick to point out that only this particular person had been receptive to the experimental T-cell therapy, but their approach could potentially help others who share the same immune-system type and tumor antigen.

How did they do it?

Yee and colleagues removed CD4+ T-cells, a type of white blood cell, from a 52-year-old man whose stage 4 melanoma had spread to a groin lymph node and to a lung. T-cells specific to targeting the melanoma were then cloned and multiplied. The grown cells were then infused into the patient. Two months later, PET and CT scans revealed no tumors. The patient remained disease free two years later, when he was last checked.

"We were surprised by the anti-tumor effect of these CD4+ T-cells and the duration of response," Yee said. "For this patient we were successful, but we would need to confirm the effectiveness of therapy in a larger study."

Yee cautioned that these results represent only one patient with a specific type of immune system whose tumor cells expressed a specific antigen. More studies are needed to confirm the effectiveness of the experimental treatment.