Noninvasive imaging in cancer immunotherapy: The way to precision medicine.

Molecular medicine requires a more precise treatment directed at molecular aberrations detected in tumors on an individual patient level. Immunotherapies empower the body's own immune system to confront tumor cells; however, their efficacy is often affected by tumor heterogeneity. Numerous noninvasive imaging techniques are available to monitor changes in tumor function reflecting therapeutic response, including immunotherapy, and to realize personalized response evaluation. For immunotherapy, strategies for using noninvasive imaging as a prognostic biomarker to identify patients who could benefit from targeted immunotherapy and predict early responders/nonresponders may ultimately lead to improved clinical management, individualized therapy regimens, and better prediction of patient outcomes. Herein, we summarize the recent progress in noninvasive imaging of immunotherapeutic targets such as immune cells, immune checkpoint inhibitors, immune vaccines, and T-cell therapy with chimeric antigen receptor, and review the clinical application of noninvasive imaging in immunotherapy. Finally, we describe the application of multimodal/multispectral imaging and radiomics, which may offer future direction for precision imaging in immunotherapy. With further progress of noninvasive imaging, guiding cancer immunotherapy into the era of precision medicine would be a promising option.