Susanna F. Greer: An unexpected GOOD sign – tumor associated macrophages and breast cancer
Susanna F. Greer, Chief Scientific Officer at the V Foundation, published the following newsletter on LinkedIn:
”This week’s Cool Cancer Find highlights a favorite protein in the world of cancer research, and one we’ve talked about in the Newsletter before: programmed cell death ligand 1 (PD-L1). This incredible protein plays a critical role in the immune system’s response to cancer. In my newsletter we often imagine the immune system as an army that fights invaders like cancer cells. PD-L1 is like a signal that some cells, including cancer cells, use to tell the immune system to hold back and not attack.
In this really cool study, V Foundation Grantee Peter Lee at City of Hope wanted to understand how PD-L1 works in a type of immune cell called tumor-associated macrophages or TAMs. TAMs are a kind of immune cell found within tumors. Previous research in the Lee lab had shown that some TAMs have PD-L1 on their surface, while others don’t. Peter Lee and team wondered what this difference might mean for how TAMs interact with the immune system and cancer cells.
To answer that question, Peter Lee investigated the genetic makeup of these TAMs in breast cancer patients. They found that TAMs with PD-L1 seemed more active compared to those without PD-L1. These PD-L1 positive TAMs also seemed to be better at stimulating other immune cells called T cells, which are important for fighting cancer.
Surprisingly, they discovered that breast cancer patients with more PD-L1 positive TAMs tend to have better outcomes. This finding was counter intuitive because PD-L1 usually tells the immune system to hold back. But in this case, it seemed like PD-L1 positive TAMs might actually help the immune system fight cancer.
To understand this better, the Peter Lee team looked at how these different TAMs interact with other cells in the tumor. They found that PD-L1 positive TAMs tend to interact more with T cells, while PD-L1 negative TAMs interact more with cancer cells. Their findings suggest that PD-L1 positive TAMs might be helping to recruit T cells to fight the cancer. Very cool, right?
I love this study because it helps shed light on how different types of immune cells in tumors can affect cancer progression in different ways. It also reminds ME to keep an open mind about cancer immunotherapy as it suggests that PD-L1 positive TAMs might be a good sign in breast cancer patients, as they could be helping the immune system fight the cancer cells.
Follow the Lee lab and their research and read their paper here.”
Source: Susanna F. Greer/LinkedIn
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