Setting cancer cells up to be gobbled

SMALL PRINT:COULD BLOCKING a "don't eat me" signal present on the surface of cancer cells help the immune system to better fight a wide variety of tumours? A new lab-based study highlights that possibility. The research looked at a molecule called CD47, which can sit on the surface of healthy blood cells as a "don't eat me" signal to stop them being gobbled up by immune cells called macrophages.

The researchers found that many types of cancer cells also had high levels of “don’t eat me” CD47 on their surfaces. They used antibodies to block these CD47 signals on various cancer cells growing in the lab, and this allowed macrophages to eat the cancer cells.

And when the researchers put a range of human solid tumours into mice and gave CD47-blocking antibodies, they saw some encouraging results.

“These results indicate that CD47-targeted antibodies will not only inhibit primary tumor growth, but may also be effective in preventing tumor metastasis ,” they write in the Proceedings of the National Academy of Sciences.

“Blocking this ‘don’t-eat-me’ signal inhibits the growth in mice of nearly every human cancer we tested, with minimal toxicity,” said researcher Irving Weissman from Stanford’s Institute of Stem Cell Biology and Regenerative Medicine, on Stanford’s website. “This shows conclusively that this protein, CD47, is a legitimate and promising target for human-cancer therapy.”

While the research has been reported enthusiastically in the press, human trials remain to be done, as the NHS Choices website points out: “. . . the research should be seen as only the first step towards developing a treatment, as we cannot yet tell whether anti-CD47 will be safe or effective in humans”.