Advances in Nanomaterial-Mediated Photothermal Cancer Therapies: Toward Clinical Applications.

Hwa Seung Han,Ki Young Choi

doi:10.3390/biomedicines9030305

Abstract

Photothermal therapy (PTT) has attracted extensive research attention as a noninvasive and selective treatment strategy for numerous cancers. PTT functions via photothermal effects induced by converting light energy into heat on near-infrared laser irradiation. Despite the great advances in PTT for cancer treatment, the photothermal therapeutics using laser devise only or non-specific small molecule PTT agents has been limited because of its low photothermal conversion efficiency, concerns about the biosafety of the photothermal agents, their low tumor accumulation, and a heat resistance of specific types of cancer. Using nanomaterials as PTT agents themselves, or for delivery of PTT agents, offers improved therapeutic outcomes with fewer side effects through enhanced photothermal conversion efficiency, accumulation of the PTT agent in the tumor tissue, and, by extension, through combination with other therapies. Herein, we review PTT’s current clinical progress and present the future outlooks for clinical applications. To better understand clinical PTT applications, we describe nanomaterial-mediated photothermal effects and their mechanism of action in the tumor microenvironment. This review also summarizes recent studies of PTT alone or in combination with other therapies. Overall, innovative and strategically designed PTT platforms are promising next-generation noninvasive cancer treatments to move closer toward clinical applications.

Highlights

Various approaches based on photothermal therapy (PTT) have been tested in preclinical studies and have shown promising results for certain cancer treatments
It is worth noting that the PTT ability of the nanomaterials can be optimized by adjusting external parameters, such as laser localization at the tumor site, laser operating conditions, and accumulation of PTT agent within the tumor tissue, as well as morphological parameters such as the size and shape of the nanomaterials
Photothermal ablation based on an external laser device has been successfully employed for tumor ablation throughout the body

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. With the increasing understanding of oncology, many advanced cancer therapies, such as immunotherapy, gene therapy, photodynamic therapy, and photothermal therapy (PTT), have drawn attention as promising and effective anticancer treatments [4,5,6,7] Among these different therapies, PTT is attractive therapeutics in oncology because of its noninvasive and selective therapeutic potential. Biomedicines 2021, 9, 305 of accumulation of small molecule PTT agents and endogenous biological chromophores in nonmalignant tissues; the need for a high power density to achieve a therapeutic effect. To achieve a better understanding of current clinical PTT approaches, we elaborate on the different types of NPAs and their photothermal effects and mechanisms of action in the TME, as well as concisely present examples of combined strategies involving PTT and other therapies. The points to be considered for future clinical applications are discussed

Photothermal Agents and Their PTT Effects in the Tumor Microenvironment

PTT in Combination with Other Cancer Therapies

Progress toward Clinical PTT Applications

Findings

Conclusions and Future Outlooks