Aspirin Boosts Effectiveness of Immunotherapy

Combination of immunotherapy and aspirin showed a substantial decrease in bowel and melanoma skin cancer growth in mice.

It has been proven in prior studies that a daily dose of aspirin in obese patients with cancer can lower the risk of colon and cervical cancer. But now recent research reveals that giving patients with cancer aspirin at the same time as immunotherapy could dramatically boost the effectiveness of the treatment.

Francis Crick Institute researchers have shown that skin, breast, and bowel cancer cells often produce large amounts of prostaglandin E2 (PGE2). PGE2 helps cancer to hide in the body’s immune system by dampening the immune system’s normal responses to attack infiltrated cells.

This tricky behavior allows tumors to thrive and may explain why some immunotherapies are not as effective as expected. Aspirin is part of a group of molecules called COX inhibitors, which stop the production of PGE2 and help reawaken the immune system.

Compared to immunotherapy alone, the combination therapy of immunotherapy with aspirin or other COX inhibitors showed a substantial decrease in bowel and melanoma skin cancer growth in mice.

“We’ve added to the growing evidence that some cancers produce PGE2 as a way of escaping the immune system,” said study author Professor Caetano Reis e Sousa, senior group leader at the Francis Crick Institute. “If you can take away cancer cells’ ability to make PGE2 you effectively life 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.”

“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,” said Peter Johnson, Cancer Research UK’s chief clinician. “Once you stop the cancer cells from producing it, the immune system switches back to ‘kill mode’ and attacks the tumor.

“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.”