Autologous Anti-Tumor Vaccines Derived from Induced Pluripotent Stem Cells Could Aid in Cancer Prevention

It may be possible to take a blood sample and make induced pluripotent stem cells (iPSCs) that are reinjected into the same individual to prevent future cancers. In a report published online ahead of print in Cell Stem Cell on February 15, 2018, researchers at Stanford University demonstrated that irradiated iPSCs were able to prevent tumor growth in murine models of breast, lung, and skin cancer.

“In our study, we use iPSCs in combination with an immunostimulant agent to activate the immune system to target epitopes that were similar between iPSCs and cancer cells,” said study investigator Joseph Wu, MD, PhD, who is director of the Stanford Cardiovascular Institute and an endowed professor in the Department of Medicine and Department of Radiology at the Stanford School of Medicine in Stanford, California.

The researchers used four groups of mice. One was injected with a control solution, one received genetically matching iPS cells that had been irradiated to prevent the formation of teratomas, one received a generic immune-stimulating adjuvant, and one received a combination of irradiated iPSCs and an adjuvant. All animals in each group were injected once a week for 4 weeks. A mouse breast cancer cell line was transplanted into the animals to observe the potential growth of tumors.

All the mice developed tumors from the breast cancer cells at the injection site. Although the tumors grew robustly in the control groups, they shrank in size in 7 of 10 mice vaccinated with iPS cells plus the adjuvant. Two of these mice were able to completely reject the breast cancer cells and live for more than 1 year after tumor transplantation.

The researchers also found immune activation and rejection of mesothelioma in a vaccinated mice group. Dr. Wu said in an orthotopic model of breast cancer, the vaccine was able to effectively activate the immune system to reject cancer cells.  He said as an adjuvant therapy after resection of melanoma, the vaccine activated the immune system, resulting in a significant decrease in cancer cells in the resected regions.

Dr. Wu envisions a patient-specific cancer vaccine that can be used at different stages of life. “You would vaccinate a high-risk patient at a certain age when they become more vulnerable to developing cancer, say 70 years, to give their immune system a boost to target cancers cells or provide memory immunity against possible future cancers,” Dr. Wu told Cancer Network. 

He said the vaccine also could be used as adjuvant therapy following surgery, chemotherapy, and/or radiation therapy. “You could start developing the vaccine at the moment the patient presents with cancer. At the time of initiating cancer treatment, you would also have the vaccine available to provide the immune system with an extra boost to fight the cancer at a time when the cancer is most vulnerable,” said Dr. Wu.