A new report from the University of Pennsylvania School of Veterinary Medicine has expanded what we know about the connection between myeloid-derived immunosuppressor cells (MDSCs) and aggressive disease. Their research has found that blocking the deltaNp63 protein on tumour cells which directs MDSCs to tumour and metastatic sites, or blocking the MDSCs themselves, reduces tumour growth and metastasis in a mouse model of triple-negative breast cancer (TNBC).

Previous studies showed that increased levels of deltaNp63 were linked to breast cancer initiation. The protein was seen to be elevated in samples of TNBC patients’ primary tumours, as were MDSC numbers.

The team used a number of mouse models and tissue transplants to determine how changing deltaNp63 levels affected cancer behaviour, and found that reducing the levels meant less metastasis in distant tissues.

The researchers concluded that two signalling molecules, CXCL2 and CCL22, reduced metastasis and blood-vessel growth associated with tumour growth when activated by the protein.

Rumela Chakrabarti, who led the study, said that a new drug which focuses on MDSCs could hugely improve TNBC treatment. In conjunction with therapies such as chemotherapy, it could give patients a more targeted option to fight their cancer.

Her lab is now moving to test this combination treatment approach with animal models and cell lines derived from breast cancer patients.