Next-generation macrophage engineering in cancer therapy: From TAM reprogramming to CAR-macrophages

Macrophages are central regulators of the tumor microenvironment (TME), shaping immune suppression, angiogenesis, metabolism, and therapeutic resistance in solid cancers. While early strategies sought to deplete tumor-associated macrophages (TAMs) or block monocyte recruitment, limited efficacy and compensatory mechanisms revealed the need for functional reprogramming rather than elimination. Recent advances in viral vectors, CRISPR-Cas genome editing, and RNA-based delivery platforms have enabled precise genetic modification of macrophages, giving rise to chimeric antigen receptor macrophages (CAR-Ms) and related engineered products. Beyond antigen targeting, effective macrophage engineering requires stabilization of pro-inflammatory identity, resistance to tumor-induced repolarization, metabolic reinforcement, and integration of checkpoint modulation pathways. This review synthesizes current strategies across DNA, mRNA, and siRNA-based platforms, highlighting convergent design principles that connect TAM reprogramming with CAR-M development. We discuss reshaping phagocytosis checkpoints, metabolic and transcriptional stabilization, cytokine augmentation, and synthetic receptor architecture, emphasizing combinatorial and context-aware engineering, while proposing new candidate gene targets. Engineered macrophages are thus evolving from simple effector cells into programmable immune coordinators capable of converting immunologically "cold" tumors into inflamed, therapy-responsive niches.