Israeli researchers spot new peptides that could point way to slaying cancer

Immunotherapy needs peptides to work, but if a patient has too few, anti-cancer drugs will fall short; discovery of new type by Weizmann Institute-led team could solve problem

Nathan Jeffay is The Times of Israel's health and science correspondent

A doctor shows medical records to cancer patient in hospital ward (iStock)
A doctor shows medical records to cancer patient in hospital ward (iStock)

Israeli researchers have found previously unknown amino acids on tumors, which could be exploited in the future to boost the effectiveness of cancer treatments.

Short chains of amino acids known as peptides are essential to the success of immunotherapy; they work by activating T cells, which fight the cancer.

But many patients don’t have enough of these peptides, which are derived from mutated cancer genes, to make immunotherapy successful.

The shortage of peptides is seen as one of the reasons that many people fail to respond to checkpoint inhibitor drugs, which block the cancer from suppressing the immune response and send the peptides into action.

“We have identified a new category of peptides, a kind that isn’t derived from the cancer DNA, which have simply been overlooked until now,” Prof. Yardena Samuels, lead scholar for the study, told The Times of Israel.

“We have also seen, in vitro, that they can activate T cells, which in turn can be reactive against cancer,” she said.

Samuels’s research was published Wednesday in the peer-reviewed journal Nature.

Illustration of T cells attacking a cancer cell (royaltystockphoto via iStock by Getty Images)

Her research is so far limited to melanoma, a lethal skin cancer, but she believes the peptide will be found in patients with other forms of cancer as well.

Samuels, her team at the Weizmann Institute of Science, and her collaborator Prof. Reuven Agami of the Netherlands Cancer Institute, named the new peptides aberrant peptides because they differ from all other known peptides.

They believe that the production of the peptide is prompted by the tumor itself.

Prof. Yardena Samuels, cancer expert from the Weizmann Institute of Science (courtesy of the Weizmann Institute of Science)

“We actually saw these peptides on the tumors,” Samuels commented.

Cancer experts could end up creating new forms of immunotherapy that don’t rely on the peptides that today’s treatment require, but rather make use of the peptides she discovered.

The use of these peptides to fight cancer remains theoretical, but finding them and realizing that they could be used to fight cancer is “exciting,” she said.

“We can’t use this as a therapy yet,” Samuels stressed. “But by showing these peptides exist and activate T cells, it could potentially enhance the effectiveness of immunotherapy in the future.”

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