Antibody slows the spread of cancers

Professor Mark Smyth and colleagues from QIMR Berghofer Medical Research Institute have discovered how to slow common cancers from metastasising, or spreading. It all comes down to three factors: immune cells known as natural killer (NK) cells, the protein CD96 and a monoclonal antibody.

The revelation follows on from the observation in 2014 that CD96, which sits on the surface of NK cells, helps to camouflage cancer cells by preventing NK cells from responding to cues from cancer cells. The role of the protein, explained Professor Smyth, is to stop the immune cells from becoming over-activated and attacking the body’s own healthy cells.

“We’ve previously found that cancers hijack this process and stop the immune system from recognising cancer cells and becoming activated,” said Professor Smyth. “This allows the cancer to spread through the body.”

In the latest finding, Professor Smyth and his colleagues have shown that an antibody can be used to block CD96, enabling more effective NK cell activation and thereby allowing the NK cells to detect and destroy the cancer cells. The finding paves the way for a new avenue in immunotherapy treatments — ie, the use of the patient’s own immune system — to fight cancer.

“Immunotherapy treatments are already proving highly successful in treating some cancers,” noted Professor Smyth. “But to date, most of the focus has been on developing new treatments that work on a different kind of immune cell known as a cytotoxic T cell.

“By contrast, we have shown that we can slow the spread of cancer by targeting natural killer cells. We think that in future this method will be just as important and effective as other immunotherapy treatments that are already in use.”

Writing in the journal Cancer Discovery, the research team stated that blocking CD96 with a monoclonal antibody inhibited experimental metastases in three different tumour models. The antibody was even more effective in slowing the spread of the cancer cells and prolonging survival when used in combination with existing agents that target and activate cytotoxic T cells.

“We think that in future a human version of this antibody will be used in combination with existing immunotherapy treatments,” Professor Smyth said.

“We hope that by activating both the NK and cytotoxic T cells, we may be able to stop the spread of cancers before they become aggressively metastatic.”