Open Access

Inhibition of photodynamic therapy induced‑immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre‑cancerous lesions (Review)

  • Authors:
    • Sharlo Bayless
    • Jeffrey B. Travers
    • Ravi P. Sahu
    • Craig A. Rohan
  • View Affiliations

  • Published online on: July 14, 2021     https://doi.org/10.3892/ol.2021.12925
  • Article Number: 664
  • Copyright: © Bayless et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Photodynamic therapy (PDT) is a treatment option for tumors and pre‑cancerous lesions, but it has immunosuppressive side effects that limit its effectiveness. Recent studies suggest that PDT‑mediated immunosuppression occurs through a cyclooxygenase type 2 (COX‑2) mediated pathway that leads to increases in regulatory T cells (Tregs) and myeloid‑derived suppressor cells (MDSCs), which act as negative regulators of immune responses. Given this pathway, there are three main methods to block immunosuppression: i) Inhibiting the proliferation of Tregs, which can be achieved with the administration of cyclophosphamide or inhibitors of indoleamine 2,3‑dioxygenase 1, an activator of Tregs; ii) inhibiting MDSCs by reducing hypoxia around the tumor to create an unfavorable environment or administering all‑trans‑retinoic acid, which converts MDSCs to a non‑immunosuppressive state; and iii) inhibiting COX‑2 through selective or non‑selective COX‑inhibitors. In the present review article, strategies that have shown increased efficacy of PDT in treating tumors and pre‑cancerous lesions by blocking the immunosuppressive side effects are outlined and discussed.
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September-2021
Volume 22 Issue 3

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Spandidos Publications style
Bayless S, Travers JB, Sahu RP and Rohan CA: Inhibition of photodynamic therapy induced‑immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre‑cancerous lesions (Review). Oncol Lett 22: 664, 2021
APA
Bayless, S., Travers, J.B., Sahu, R.P., & Rohan, C.A. (2021). Inhibition of photodynamic therapy induced‑immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre‑cancerous lesions (Review). Oncology Letters, 22, 664. https://doi.org/10.3892/ol.2021.12925
MLA
Bayless, S., Travers, J. B., Sahu, R. P., Rohan, C. A."Inhibition of photodynamic therapy induced‑immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre‑cancerous lesions (Review)". Oncology Letters 22.3 (2021): 664.
Chicago
Bayless, S., Travers, J. B., Sahu, R. P., Rohan, C. A."Inhibition of photodynamic therapy induced‑immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre‑cancerous lesions (Review)". Oncology Letters 22, no. 3 (2021): 664. https://doi.org/10.3892/ol.2021.12925