Progress in multimodal imaging-guided photothermal anti-tumor combined therapy

Abstract

As one of the diseases with high morbidity and low cure rate in the world, cancer has always threatened the health of the public. However, due to the complexity, diversity and heterogeneity of the tumor, it is difficult to inhibit tumor recurrence and metastasis by relying on surgery, radiotherapy or chemotherapy. Photothermal therapy (PTT) is a cancer treatment by laser irradiation, which converts light energy into heat energy mediated by photothermal agents, and induces local tissue hyperthermia to treat cancer. And it has attracted widespread attention because of its non-specificity, high tumor ablation efficiency, and low toxic side effects on normal cells. However, the clinical transformation process of PTT is also severely limited by some disadvantages including the inconvenience of the delivery, distribution and metabolic process of the photothermal agent and the inaccurate and incomplete evaluation of the results of cancer treatment. The researchers have designed a variety of photothermal agents with multimodal imaging capabilities for cancer diagnosis and treatment. These imaging methods include thermal imaging (TI), photoacoustic (PA) imaging, photoluminescence (PL) imaging, magnetic resonance imaging (MRI), X-ray computed tomography (CT) imaging, and positron emission tomography (PET) imaging. And the imaging-guided cancer treatments have improved the accuracy of tumor visual treatments and greatly facilitated the clinical transformation of PTT. At present, the trend of cancer treatment development has gradually changed from monotherapy to combination therapy. Other therapies in combination with PTT include photodynamic therapy (PDT), chemotherapy, immunotherapy, radiotherapy (RT), sonodynamic therapy (SDT), and other PTT-related therapies. These combination therapies overcome tumor heterogeneity and complexity, reversing multidrug resistance, and reduce unnecessary side effects, and can more effectively achieve cancer diagnosis and treatment. This review summarizes the recent advances in multimodal imaging-guided PTT and multitherapies in combination with PTT for cancer diagnosis and treatment. For a single photothermal treatment, it is often difficult for researchers to effectively monitor the delivery, distribution, metabolism, and excretion of photothermal agents, and to accurately and dynamically track and evaluate the real-time therapeutic effects of tumors. Various strategies have been developed to solve the problems of single photothermal therapy. The new nano-platforms based on PTT-based multimodal imaging methods or therapies reviewed in this paper combine cancer diagnosis and treatment, and effectively overcome the shortcomings of single photothermal anti-tumor therapy, which is difficult to visualize tumors and lack of therapeutic efficiency to provide the development of new cancer diagnosis and treatment technologies new opportunities. Whether it is a single photothermal therapy or a combination of photothermal therapy and other methods, there is still a long way to go to study its therapeutic mechanism and further applications. The ultimate goal of these studies is to go to the clinic, cure the tumor, and benefit mankind. It is believed that with the rapid development of nanotechnology and nanomedicine, these problems will be gradually solved, and the photothermal anti-tumor combination therapy based on multimodal imaging will surely make new breakthroughs.