The approval of gene therapy for leukemia, expected in the next few months, will open the door to a radically new class of cancer treatments.

Companies and universities are racing to develop these new therapies, which re-engineer and turbocharge millions of a patient’s own immune cells, turning them into cancer killers that researchers call a “living drug.” One of the big goals now is to get them to work for many other cancers, including those of the breast, prostate, ovary, lung and pancreas.

“This has been utterly transformative in blood cancers,” said Dr. Stephan Grupp, director of the cancer immunotherapy program at the Children’s Hospital of Philadelphia, a professor of pediatrics at the University of Pennsylvania and a leader of major studies. “If it can start to work in solid tumors, it will be utterly transformative for the whole field.”

But it will take time to find that out, he said, at least five years.

This type of treatment is now also being studied in glioblastoma, the aggressive brain tumor that Senator John McCain was found to have this week. Results of a study at the University of Pennsylvania, published Wednesday, were mixed. In the first 10 patients treated there, one has lived more than 18 months with what the researchers called “stable disease.” Two other survivors have cancer that has progressed, and the rest have died.