While macrophages remain a promising therapeutic target in multiple cancer types, recent reports concerning acquired resistance in different tumours to therapeutic agents that specifically target macrophages, such as anti-CCL2/CCR2 or anti-M-CSFR, highlight that it will be important to characterise potential resistance mechanisms when we develop agents that target macrophages in the tumour microenvironment. This evidence concerns the gene CSF1R and neoplasm.