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Training immune cells with genes harvested from a patient’s own tumor could make an already promising new cancer treatment even better.

A highly personalized medical technique is allowing patients with advanced kidney cancer to live nearly three times as long as they normally do. In an experiment involving 21 patients, around half lived more than two and half years after diagnosis with kidney cancer that had begun to spread. Five patients are alive after more than five years.

“That seems to be out of proportion with what you would expect for any commercial therapy and longer than what you would expect from patients with similar prognostic variables,” says Robert Figlin, an oncologist at Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute in Los Angeles, who is leading the study.

The findings are part of a large wave of positive results coming from a class of oncology treatments called cancer immunotherapies. Many drug companies, large and small, are working on treatments that instigate the immune system to attack cancer (see “The Revival of Cancer Immunotherapy”). There are a variety of methods for revving up immune cells. In some cases, like the experimental kidney cancer treatment, doctors train a patient’s own white blood cells to spot a cancer cell among its harmless neighbors.

Most so-called cancer vaccines are off-the-shelf products that teach immune cells to attack cancer cells bearing a particular protein. Since cancer is known for its tendency to mutate, these off-the-shelf treatments “may be targeting something that doesn’t exist in each patient,” says Jeff Abbey, CEO of Argos Therapeutics, the Durham, North Carolina, biotech that developed the kidney cancer treatment. Argos is taking a more personalized approach. “We think that the only way to win is to do an active specific immunotherapy that captures all the mutations,” Abbey says.

Argos’s therapy begins with a piece of a tumor removed in cancer surgery. From that bit of biological material, scientists at the company extract RNA, the molecular cousin of DNA, which represents all active genes in the tumor cells. The collection of active genes then becomes a vaccine for the patient’s immune system. Two or three weeks after the cancer surgery, doctors collect white blood cells from the patient in a process similar to blood donation. Those immune system cells then get shipped to Argos, which modifies them with the tumor genes and some chemicals so that they learn to target the mutations found specifically in a patient’s own cancer cells. The cells then alert other immune system cells to attack the cancer.

“If we can prove that it works, it will be a game changer for how we think about generating immune responses against cancer,” says Figlin.

The proof will be in whether 450 patients in an ongoing randomized study experience the benefits seen in the smaller trial, he says.