Could a shot in the arm successfully attack cancers in virtually any part of the body?

An international team of researchers says they have made progress along those lines.

Writing in this month’s edition of the journal Nature, the researchers stated they have taken a “positive step” toward developing a universal cancer vaccine.

Their method involves using RNA as a way to stimulate the immune system to attack cancer cells.

While the results are quite preliminary, they did produce some optimism in the cancer research community.

“The approach for systemic delivery of an RNA-lipid complex vaccine for cancer in this report is really interesting,” William Chambers, Ph.D., the American Cancer Society’s senior vice president for extramural research, told Healthline in a statement. “The data strongly support continued development of this approach and I am hopeful and looking forward to seeing if the promise of this work can be fulfilled.”

Ritika Jaini, Ph.D., assistant professor of molecular medicine at the Lerner Research Institute at the Cleveland Clinic in Ohio, is likewise cautiously optimistic.

She said the RNA approach is an “excellent mode of delivery,” although she is uncertain whether a single vaccine could be effective against all cancers because of the immense diversity in the kinds of tumors in the human body.

“I don’t see [a single vaccine] happening,” she told Healthline. “I think it would have to be personalized medicine.”

Read More: Immune Systems Now a Major Focus of Cancer Treatment Research »

How Cancer Vaccines Work

Vaccines for specific types of cancer have been on the marketplace in the United States for the past six years.

But there are still only a handful available.

The first one was approved by the Food and Drug Administration (FDA) in 2010.

The vaccine, called Provenge, is used to treat advanced prostate cancer. It uses white blood cells called dendritic cells that are taken out of a patient and then reintroduced into the bloodstream.

Since 2010, two other vaccines have been introduced for specific cancers, according to the National Cancer Institute.

Both are preventative treatments. One vaccine is used to block the human papillomavirus (HPV). The other is used against hepatitis B.

A universal vaccine, however, would be used against most types of cancer.

In the recent experiment, researchers took pieces of a cancer’s RNA genetic code and then put them into nanoparticles of fat, according to a story on the website of the Independent.

They then injected the mixture into the bloodstream of three patients with advanced cancer.

The researchers reported that the patients’ systems responded by producing T-cells designed to attack cancer.

In one patient, a tumor of a lymph node got smaller. Another patient, whose tumors had been surgically removed, was free of cancer seven months after getting the vaccine.

In a third patient, eight tumors that had spread from skin cancer into the lungs were reported as “clinically stable” after the vaccine.

A researcher told the Independent the vaccine also effective against aggressive tumors in mice.

Read More: HPV Cases Have Dropped Dramatically Since Vaccine Was Introduced »

Will It Work?

Jaini said a delivery system such as the RNA in this experiment is an important part of cancer treatment, but it is only one component.

She said researchers also need to identify targets such as antigens in cancer cells for a vaccine to be effective.

Different cancers appear to have different antigens, making a universal treatment somewhat elusive.

“It would be great if we could find one target for all cancers,” Jaini said.

Nonetheless, she said the RNA component in this research is “new and groundbreaking” and could lead to some effective delivery systems.

While cancer research money still needs to be spent on other areas such as biomarkers, Jaini said some time and effort should go into this RNA-based delivery mode.

“I think it looks very promising,” she said.

Read More: Tetanus Shots Help Brain Cancer Patients Live Five Times Longer »