Solutions to the Drawbacks of Photothermal and Photodynamic Cancer Therapy

Abstract

Phototherapy such as photothermal therapy and photodynamic therapy in cancer treatment has been developed quickly over the past few years for its noninvasive nature and high efficiency. However, there are still many drawbacks in phototherapy that prevent it from clinical applications. Thus, scientists have designed different systems to overcome the issues associated with phototherapy, including enhancing the targeting ability of phototherapy, low-temperature photothermal therapy, replacing near-infrared light with other excitation sources, and so on. This article discusses the problems and shortcomings encountered in the development of phototherapy and highlights possible solutions to address them so that phototherapy may become a useful cancer treatment approach in clinical practice. This article aims to give a brief summary about current research advancements in phototherapy research and provides a quick guideline toward future developments in the field.

Keywords: cancer treatment; clinical potential; photodynamic therapy; phototherapy; photothermal therapy.

Scheme 1

Schematic presentation of phototherapy. Drawn by Adobe Illustrator.

Figure 1

Illustration showing the use of GA‐containing nanosystem to overcome thermal resistance by inhibiting HSP90. Reproduced with permission.^[39] Copyright 2017, WILEY‐VCH Verlag GmbH & Co.

Figure 2

Triple combination of biotherapy, PTT, and sustained PD‐1 blockage therapy by pDA‐VNP to trigger robust antitumor immune response. Reproduced with permission.^[64] Copyright 2020, WILEY‐VCH Verlag GmbH & Co.

Figure 3

A) Chemical structures of the two iridium(III) complexes and their ability to target mitochondria and lysosomes for PDT. Reproduced with permission.^[72] Copyright 2016, WILEY‐VCH Verlag GmbH & Co. B) Preparation of IR‐Pyr‐encapsulated nanosystem for mitochondria‐targeted PDT. Reproduced with permission.^[75] Copyright 2017, Royal Society of Chemistry.

Figure 4

Two main research aspects to improve hypoxia: 1) catalyze the excess hydrogen peroxide inside the tumor to generate oxygen in situ for oxygen supply and 2) transport oxygen from other parts to the tumor.

Figure 5

A mesoporous nanoenzyme used as the scaffold for uniformly dispersing the loaded photosensitizers to achieve enhanced PDT of tumor. Reproduced with permission.^[77] Copyright 2019, WILEY‐VCH Verlag GmbH & Co.

Figure 6

Schematic illustration of the combination therapy based on sonosensitizer‐associated SDT and anti‐PD‐L1 checkpoint blockade immunotherapy for enhanced tumor treatment. Reproduced with permission.^[96] Copyright 2019, Springer Nature Limited.

Figure 7

Combination of different therapy methods with PTT and PDT. Drawn by Adobe Illustrator.