Using stem cells to generate an immune attack against cancer

Induced pluripotent stem cells (iPSCs) have the power to transform into any cell in the body, making them a prime candidate for regenerative medicine. But can they also teach the immune system to recognize and attack cancer?

Scientists at Stanford University believe iPSCs can do just that—and they tested the concept in mouse models of breast cancer. When they injected mice with inactivated IPSCs, the animals’ immune systems launched an attack against cancer and prevented relapse after tumors had been removed, according to a press release from the university. The study was published in the journal Cell Stem Cell.

The Stanford researchers used cells from each of the 75 mice in the study to create an iPSC vaccine that targeted several tumor “antigens,” which are markers on the surface of cells that immunotherapies target. The scientists discovered that many antigens on iPSCs are also present on tumor cells, so they were able to use whole iPSCs rather than having to pick a single antigen to target.

Four weeks after the mice received injections of the cells, 70% of the animals did not develop tumors after breast cancer cells were injected into them. The other 30% developed small tumors, according to a statement from Cell Press.

"When we immunized an animal with genetically matching iPS cells, the immune system could be primed to reject the development of tumors in the future,” said senior author Joseph Wu, M.D., Ph.D., professor and director of Stanford's Cardiovascular Institute, in a separate statement. “Pending replication in humans, our findings indicate these cells may one day serve as a true patient-specific cancer vaccine."

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Here’s how it might work in people: Cells taken from a patient’s skin or blood would be reprogrammed into iPSCs and then injected, perhaps after surgery, chemotherapy or another cancer treatment.

The publication of iPSC study comes on the heels of another study out of Stanford involving a different type of cancer vaccine. In the journal Science Translational Medicine, a team from the school reported progress combining a short stretch of DNA with an antibody to prime the immune system to launch attacks against several tumor types. Stanford is planning a clinical trial of that vaccine in 15 patients with lymphoma.

In December, researchers at the University of California in San Francisco started a trial of a therapeutic cancer vaccine that targets misshapen proteins on the surface of brain cancer cells.

The next step for Stanford’s iPSC researchers will be to test their vaccines in samples of human cancers, Wu said.

"What surprised us most was the effectiveness of the iPSC vaccine in reactivating the immune system to target cancer," he said in the statement from Cell Press. "This approach may have clinical potential to prevent tumor recurrence or target distant metastases."