Drug to block immune system could stop cancer rebound

Combining chemotherapy with a drug that blocks part of the immune system from going into overdrive might help prevent cancer relapse in some people, a new study has found.
Scientists found that the cancer-killing action of chemotherapy can trigger a swarm of wound-healing, white blood cells to cluster around blood vessels in a treatment-hit tumour.
Macrophages are a type of white blood cells and are often found in two forms in the body - M1 macrophages, which protect against infection and can work to destroy tumours, and M2 macrophages which promote wound-healing and have been linked to tumour growth and spread.

Scientists targeted and blocked the accumulation of M2 cells in tumours after chemotherapy.
M2 macrophages repair tissue damage and build new blood vessels, a process that sometimes helps the tumour to grow again after treatment.
However, by treating mice with cancer with drug called Plerixafor that stops these repair cells from working, the researchers markedly reduced the speed at which tumours grew back after chemotherapy.

"Scientists already knew that the body's drive to heal itself can sometimes backfire when the immune system reacts to tissue damage," said lead researcher Claire Lewis, at the University of Sheffield's Department of Oncology.
"Our research shows that treating tumours with chemotherapy can activate this part of the immune system, and this then helps tumours re-grow afterwards," Lewis said.

"But combining chemotherapy with a drug that switches off this part of the body's repair system, slowed the growth of tumours after chemotherapy," she said.
"This could be particularly important for patients who can't have surgery and, therefore, need chemotherapy to help them live for as long as possible," she said.
Clinical trials of patients are needed to confirm these early findings to see if the drug - already used in patients for other reasons, such as bone marrow transplants - could help cancer patients after chemotherapy.
"Chemotherapy is a cornerstone cancer treatment that saves thousands of lives, but sometimes tumours come back, reducing patients' chances of survival," said Aine McCarthy, science communications officer at Cancer Research UK.

"We don't understand all the reasons why tumours do come back, but this study sheds new light on the role of the immune system in causing tumours to grow again and, importantly, identifies a drug that could block this happening if given at the same time as chemotherapy," said McCarthy.
The study was published in the journal Cancer Research.