Cancer remains a major worldwide health challenge. Current studies emphasize the tumor microenvironment that plays a vital role in tumor proliferation, invasion, metastasis, and drug resistance. The tumor microenvironment (TME) supports the cancer cell to evade conventional treatment such as surgery, radiotherapy, and chemotherapy. Moreover, the components of tumor microenvironments have a major contribution towards developing therapy resistance in solid tumors. Therefore, targeting the tumor microenvironment can be a novel approach for achieving advancement in cancer nanomedicine. The recent progress in understanding TME and developing TME-responsive nanoparticles offers a great advantage in treating cancer drug resistance. These nanoparticles are developed in response to TME stimuli such as low pH, redox, and hypoxia improve nanomedicine's pharmacokinetic and therapeutic efficacy. This review discusses the various components of the tumor microenvironment responsible for drug resistance and nanomedicine's role in overcoming it.

Immunotherapy has gathered significant attention and is now a widely used cancer treatment that uses the body’s immune system to fight cancer. Despite initial successes, its broader clinical application is hindered by limitations such as heterogeneity in patient response and challenges associated with the tumor immune microenvironment. Recent advancements in nanotechnology have offered innovative solutions to these barriers, providing significant enhancements to cancer immunotherapy. Nanotechnology-based approaches exhibit multifaceted mechanisms, including effective anti-tumor immune responses during tumorigenesis and overcoming immune suppression mechanisms to improve immune defense capacity. Nanomedicines, including nanoparticle-based vaccines, liposomes, immune modulators, and gene delivery systems, have demonstrated the ability to activate immune responses, modulate tumor microenvironments, and target specific immune cells. Success metrics in preclinical and early clinical studies, such as improved survival rates, enhanced tumor regression, and elevated immune activation indices, highlight the promise of these technologies. Despite these achievements, several challenges remain, including scaling up manufacturing, addressing off-target effects, and navigating regulatory complexities. The review emphasizes the need for interdisciplinary approaches to address these barriers, ensuring broader clinical adoption. It also provides insights into interdisciplinary approaches, advancements, and the transformative potential of nano-immunotherapy and promising results in checkpoint inhibitor delivery, nanoparticle-mediated photothermal therapy, immunomodulation as well as inhibition by nanoparticles and cancer vaccines.