Giving cancer patients aspirin at
the same time as immunotherapy could dramatically boost the
effectiveness of the treatment, according to new research published
in the journal Cell today (Thursday).
Francis Crick Institute
researchers, funded by Cancer Research UK, have shown that skin,
breast and bowel cancer cells often produce large amounts of
prostaglandin E2 (PGE2). This molecule dampens down the immune
system's normal response to attack faulty cells, which helps cancer
to hide. It is a trick that allows the tumour to thrive and may
explain why some immunotherapy treatments have not been as
effective as hoped.
Aspirin is part of a group of
molecules called COX inhibitors, which stop the production of PGE2
and help reawaken the immune system. Combining immunotherapy with
aspirin or other COX inhibitors substantially slowed bowel and
melanoma skin cancer growth in mice, compared to immunotherapy
alone*.
Study author Professor Caetano Reis
e Sousa, senior group leader at the Francis Crick Institute, said:
"We've added to the growing evidence that some cancers produce PGE2
as a way of escaping the immune system. If you can take away cancer
cells' ability to make PGE2 you effectively lift this protective
barrier and unleash the full power of the immune system.
"Giving patients COX inhibitors
like aspirin at the same time as immunotherapy could potentially
make a huge difference to the benefit they get from treatment. It's
still early work but this could help make cancer immunotherapy even
more effective, delivering life-changing results for patients."
Professor Peter Johnson, Cancer
Research UK's chief clinician, said: "PGE2 acts on many different
cells in our body, and this study suggests that one of these
actions is to tell our immune system to ignore cancer cells.
Once you stop the cancer cells from producing it, the immune
system switches back to 'kill mode' and attacks the tumour.
"This research was carried out in
mice so there is still some way to go before we will see patients
being given COX inhibitors as part of their treatment. But it's an
exciting finding that could offer a simple way to dramatically
improve the response to treatment in a range of cancers."
The paper, Cyclooxygenase-Dependent
Tumor Growth through Evasion of Immunity, is
published in Cell.
*The type of immunotherapy tested was anti-PD-1. For more
information on how these treatments work, you can read Cancer
Research UK's blog here and watch their animation on cancer immunotherapy via
this link.