Renewed hope for a cancer breakthrough with killer T cells (VIDEO)

Hope exists for a cancer breakthrough after scientists altered the T cells of leukemia sufferers — part of their own immune system — to successfully kill off cancer cells.  

Two of three patients who had the genetically modified T cells infused back into their body following chemotherapy, remained cancer-free for more than a year. One patient showed significant improvement.

"This is a huge accomplishment — huge," Dr. Lee M. Nadler of Harvard Medical School told the Los Angeles Times of the trial cancer treatment, reportedly 20 years in the making.

The treatment, pioneered by researchers at the University of Pennsylvania, involves infecting the white blood cells of patients with advanced chronic lymphocytic leukemia with a virus, and instructing those T cells to bind to cancer cells and ultimately kill them.

In each of the three patients studied, each virus-infected T cell killed about 1,000 cancer cells, according to the scientists' findings, published in the New England Journal of Medicine and Science Translational Medicine.

"Within three weeks, the tumors had been blown away, in a way that was much more violent than we ever expected," senior author Dr. Carl H June said, the Times reports.

The scientists cautioned that the full effectiveness of the treatment could only be known once it was administered to a larger pool of patients.

Meanwhile, CNN was already discussing the broader implications of what could potentially be "cancer's serial killer:

Dr. David Porter of the University of Pennsylvania, who co-wrote both of the trial's reports, was optimistic.

"We knew [the therapy] could be very potent," Porter said. "But I don't think we expected it to be this dramatic on this go-around."