Tumor Microenvironment-Responsive Nanomedicine: Monitoring and Modulating the Tumor Microenvironment for Precision Cancer Therapy.

The tumor microenvironment (TME) is a dynamic and heterogeneous ecosystem whose abnormal vasculature, dense extracellular matrix, metabolic reprogramming and immunosuppression collectively hinder drug penetration, drive therapeutic resistance and limit responses to immunotherapy. TME-responsive nanomedicine provides an emerging toolbox to both monitor and actively remodel the microenvironment for precision cancer therapy. In this narrative review, we first summarize key pathological features of the TME and their impact on drug delivery across classical barriers, including the blood-brain, cutaneous and ocular interfaces, as well as circulating and bone-marrow niches in hematologic malignancies. We then discuss design principles of endogenous and exogenous stimuli-responsive nanoplatforms, and how these systems enable TME monitoring via liquid biopsy, spatial multi-omics and real-time imaging, and TME modulation through metabolic reprogramming, immune activation, vascular normalization and extracellular-matrix remodeling. Finally, we highlight major translational challenges and future opportunities, emphasizing the roles of artificial intelligence, multiscale and quantum-inspired modeling, and closed-loop theranostic strategies in optimizing TME-responsive nanomedicines for clinically meaningful benefit.