Clinical relevance of tumour-associated macrophages

In the past decade, substantial advances have been made in understanding the biology of tumour-associated macrophages (TAMs), and their clinical relevance is emerging. A particular aspect that is becoming increasingly clear is that the interaction of TAMs with cancer cells and stromal cells in the tumour microenvironment enables and sustains most of the hallmarks of cancer. Therefore, manipulation of TAMs could enable improved disease control in a substantial fraction of patients across a large number of cancer types. In this Review, we examine the diversity of TAMs in various cancer indications and how this heterogeneity is being revisited with the advent of single-cell technologies, and then explore the current knowledge on the functional roles of different TAM states and the prognostic and predictive value of TAM-related signatures. We also review agents targeting TAMs that are currently being or will soon be tested in clinical trials, and how manipulations of TAMs can improve existing anticancer treatments. Finally, we discuss how TAM-targeting approaches could be further integrated into routine clinical practice, considering a precision oncology approach and viewing TAMs as a dynamic population that can evolve under treatment pressure. The interaction of tumour-associated macrophages (TAMs) with cancer and stromal cells in the tumour microenvironment enables and sustains most of the hallmarks of cancer. The authors of this Review examine the diversity of TAMs in various cancer indications, which is being revisited with the advent of single-cell technologies, and discuss the functional roles of different TAM states, the prognostic and predictive value of TAM-related signatures as well as approaches involving TAMs that are currently being or will soon be tested in clinical trials.