A team of researchers from Baylor College of Medicine and affiliated organizations has successfully identified a tactic employed by cancerous tumours to remotely interfere with immune response development, which could potentially impede their proliferation.

Researchers discover a way of accelerating bone marrow recovery

The researchers have also discovered ways of expediting the restoration of normal bone marrow conditions following the removal of tumours, thus accelerating immune system recovery.

According to Dr Xiang H.-F. Zhang, the corresponding author and interim director of the Lester and Sue Smith Breast Center at Baylor, breast cancer can have significant effects on the body even before spreading to other parts. Tumours disrupting the bone marrow ecosystem can lead to an immune response that promotes tumour growth instead of attacking it. The team conducted a study on breast cancer animal models to understand this process, revealing that even small tumours can induce multiple changes in the bone marrow with profound consequences.

According to Dr Xiaoxin Hao, the study’s first author, breast cancer stimulates the excessive production of osteoprogenitor cells in the bone marrow. Additionally, there is an increase in the number of progenitor cells associated with immune cell development. These progenitor cells relocate close to the osteoprogenitor cells and establish communication, particularly with a subset known as granulocyte-monocyte progenitors (GMPs).

GMP produce cells that suppress the immune response

This communication between osteoprogenitor cells and GMPs is crucial as GMPs give rise to immune cells that accumulate in breast cancer tumours and suppress the anti-tumour immune response, promoting tumour growth. Surprisingly, even after tumour removal, the bone marrow disruption does not immediately recover, as observed in animal models. This prolonged impact is clinically relevant, as some patients show increased levels of neutrophils in their blood even more than 40 weeks after tumour removal. After tumour removal, immunotherapy is sometimes administered, hinging on the effectiveness of the immune system. These findings indicate that the immune system remains compromised in certain patients even after tumour removal, potentially diminishing the positive outcomes of immunotherapy. In addition, the results correlate to metastasis, which could occur years later because of lingering cancer cells following initial surgery.