Radiotherapy, photodynamic therapy, and cryoablation‐induced abscopal effect: Challenges and future prospects

Abstract

Local therapy modalities such as radiation therapy, photodynamic therapy, photothermal therapy, and cryoablation have been used to treat localized tumors for decades. The discovery of the abscopal effect causes a paradigm shift where local therapy also causes systemic effects and leads to the remission of nonirradiated tumors. The abscopal effect of radiation therapy, alone or in combination with other treatments, has been extensively studied over the last six decades. However, the results are unsatisfactory in producing robust, reproducible, and long‐lasting systemic effects. Although immunotherapy and radiation therapy are promising in producing the abscopal effect, the abscopal effect's mechanism is still unclear, owing to various factors such as irradiation type and dose and cancer type. This article reviews the research progress, clinical and preclinical evidence of the abscopal effect by various local therapies alone and in combination with chemotherapy and immunotherapy, case reports, and the current challenges in producing the abscopal effect by various local therapies, focusing on radiotherapy, photodynamic therapy, cryoablation, and the prospects for obtaining a robust, reproducible, and long‐lasting abscopal effect.

Understanding the Photodynamic Therapy Induced Bystander and Abscopal Effects: A Review

“…Similarly, the generation of certain reactive nitrogen species (RNS) (Table 1) and several immuno-or non-immuno-stimulatory molecules has been investigated with respect to PDT-stress induced bystander effects. Additionally, several other factors may also be responsible for influencing the bystander or abscopal responses in PDT, including the type and concentration of photosensitizer used, the wavelength and intensity of light used, and the microenvironment of the tumor [2,4,23] (Table 1). [17], necroptosis, and ferroptosis [16,18], cell signaling, oxidative stress, and immune response [2,4,23] For PDT, three PS generations have been introduced.…”

“…With more mechanistic insights and clinical studies, other non-conventional local and nonionizing radiation therapies like PDT have also been shown to induce the bystander and abscopal effects. However, there is a great deal that is still unknown regarding issues like the nature of signaling, different types of reactions, and the mediator molecules involved [2][3][4].…”

Alternative Non-Drug Treatment Options of the Most Neglected Parasitic Disease Cutaneous Leishmaniasis: A Narrative Review

“…Cryotherapy destroys affected tissues and kills amastigotes by causing intracellular and extracellular ice crystal production and alterations in the cell membrane [ 15 ]. Cryonecrosis results in the release of antigenic compounds that stimulate immune responses and repair further lesions [ 16 ]. Although painful, it is a simple, inexpensive, and rapid procedure devoid of the need for local anesthesia [ 16 ].…”

“…Cryonecrosis results in the release of antigenic compounds that stimulate immune responses and repair further lesions [ 16 ]. Although painful, it is a simple, inexpensive, and rapid procedure devoid of the need for local anesthesia [ 16 ]. With few reported cases of burning and the possibility of secondary infections after treatment with cryotherapy [ 17 ], it can be a helpful alternative to chemotherapy for the treatment of CL.…”

Advances in Peptide-Decorated Targeted Drug Delivery: Exploring Therapeutic Potential and Nanocarrier Strategies

“…Their small size allows them to reach the target site directly through a pathophysiological phenomenon called the enhanced permeability and retention effect (EPR), or through the surface receptors. The advantages of these nanoparticles include increased dosage efficacy, higher bioavailability, stealth nature, and minimal side effects of the chemotherapeutic drugs owing to the targeted delivery. − …”