Targeting cancer-associated fibroblasts: Challenges, opportunities and future directions

Cancer associated fibroblast (CAF) are a common cell in the tumour microenvironment with diverse tumourpromoting functions.Their presence in tumours is commonly associated with poor prognosis making them attractive therapeutic targets, particularly in the context of immunotherapy where CAF have been shown to promote resistance to checkpoint blockade.Previous attempts to inhibit CAF clinically have not been successful however, in part due to a lack of understanding of CAF heterogeneity and function, with some fibroblast populations potentially being tumour suppressive.Recent single cell transcriptomic studies have advanced our understanding of fibroblast phenotypes in normal tissues and cancers, allowing for a more precise characterisation of CAF subsets and providing opportunities to develop new therapies.Here we review recent advances in the field, focusing on the evolving area of therapeutic CAF targeting.