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New findings expand hopes for a stem cell cancer ‘vaccine’

Induced pluripotent stem cells share proteins with some cancers. The cells can be used as a vaccine to prevent pancreatic cancers in mice.

One perk of being an 'experienced' science writer is the opportunity to follow-up on promising research over the years. I love charting the course of scientific research from the first gleam in a researcher's eye, to animal studies, to clinical trials and even -- sometimes -- a bonafide new treatment for a deadly disease.

I've written about stem cells and cancer for well over a decade. When I started, there were concerns about whether using stem cells as therapy for a variety of regenerative diseases could cause cancers if the powerful cells eluded the body's regulatory pathways that police adult cells and tissues. In 2018, however, I wrote about a novel new idea: Used in another way, could stem cells actually work to prevent the development of cancer?

Mimicking cancer cells

In my previous article, I explained how the cells, called induced pluripotent stem cells, or iPS cells, might work to prevent cancer:

The iPS cells work as an anti-cancer vaccine because, like many cancer cells, they resemble developmentally immature progenitor cells, which are free from the growth restrictions built into mature cells that make up the body's tissues. Injecting iPS cells that genetically match the recipient, but that are unable to replicate, can safely expose the immune system to a variety of cancer-specific targets, the researchers found.

The researchers, led by Stanford cardiovascular researcher Joseph Wu, MD, PhD, had found that the injection of iPS cells and an immune-stimulating agent known as an adjuvant into laboratory mice could prevent the formation of cancers when the animals were subsequently injected with mouse breast cancer, skin cancer or mesothelioma cells. (The iPS cells are treated before injection with radiation to ensure they won't replicate in the mice, which could cause new, unrelated, tumors.)

Now, Wu and postdoctoral scholar Xiaoming Ouyang, PhD, have extended this finding to include mice injected with mouse pancreatic cancer cells. (Pancreatic ductal adenocarcinoma, the most common type of pancreatic cancer, is the fourth leading cause of cancer deaths in the United States.) As in the previous study, injecting iPS cells made from the animals' own tissues, along with an adjuvant, made them resistant to pancreatic cancer tumors that readily formed in control animals without the iPS cells. They published their results recently in Stem Cell Reports.

"When we vaccinated the mice, and then challenged them with the pancreatic cancer cells, 75% of the animals that had received iPS cells plus the adjuvant didn't develop any tumors at all," Ouyang said. "In contrast, all of the control animals developed cancers."

Subsequent experiments indicate that the technique may also work for some other types of solid cancers, including a type of brain cancer called glioblastoma multiforme.

Cancer clinical trials, universal vaccine?

Amping up the immune system's response to cancer cells might also help to eliminate existing tumors, the researchers believe. They hope to begin testing the approach in people in a clinical trial. "At first, we'll combine the iPS-cell-based 'vaccine' in people with solid tumors receiving traditional surgery and chemotherapy for solid tumors like pancreas or colon cancers," Wu said. "We hope that, by stimulating the immune system, we can increase the killing of the cancer cells. If that is successful, we will try the vaccine in healthy people who have a high risk of developing certain familial cancers."

Initially, the researchers will use iPS cells that are created directly from each patient's own tissue. They hope that, if the approach proves successful in people, it might one day be possible to have a one-size-fits-all vaccine based on the proteins on the cells that trigger an immune response against these cancers.

"We are looking into this possibility now," Wu said. "A universal vaccine would be an incredible step forward in the field of cancer prevention and therapy."

Fingers crossed I get to tell you all about it some day. ...

Image by LASZLO

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