The use of 5-aminolevulinic acid and its derivatives in photodynamic therapy and diagnosis

5-aminolevulinic acid (5-ALA) is used as a drug in the photodynamic therapy (PDT) and photodynamic diagnosis (PDD) of cancer. Combined with irradiation at the appropriate wavelength, it is used as a photosensitizer precursor to identify/kill tumour cells. In cells, 5-aminolevulinic acid is converted to protoporphyrin IX (PpIX), which is the precursor of hemin. Internal application of 5-ALA induces the overproduction of the endogenous photosensitizer, PpIX, which can subsequently be activated by light at the appropriate wavelength. 5-ALA can be applied internally to trans-mutated areas or be injected directly into them. Chemical derivatives of 5ALA have the potential to improve bioavailability, enhance stability and lead to better therapeutic outcomes for treated patients. 5-ALA is currently the most commonly used drug in the photodynamic therapy and diagnosis (PDT/PDD) of cancers. Keywords: photodynamic therapy, photodynamic diagnosis, 5-aminolevulinic acid (5- ALA), esters of 5-aminolevulinic acid, cancer.

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Systematic Review and Meta-Analysis of In Vitro Anti-Human Cancer Experiments Investigating the Use of 5-Aminolevulinic Acid (5-ALA) for Photodynamic Therapy

Pharmaceuticals ◽

10.3390/ph14030229 ◽

2021 ◽

Vol 14 (3) ◽

pp. 229

Author(s):

Yo Shinoda ◽

Daitetsu Kato ◽

Ryosuke Ando ◽

Hikaru Endo ◽

Tsutomu Takahashi ◽

...

Keyword(s):

Systematic Review ◽

Photodynamic Therapy ◽

Aminolevulinic Acid ◽

Human Cancer ◽

Meta Analysis ◽

Protoporphyrin Ix ◽

Cell Types ◽

Amino Acid Derivative ◽

Photodynamic Diagnosis

5-Aminolevulinic acid (5-ALA) is an amino acid derivative and a precursor of protoporphyrin IX (PpIX). The photophysical feature of PpIX is clinically used in photodynamic diagnosis (PDD) and photodynamic therapy (PDT). These clinical applications are potentially based on in vitro cell culture experiments. Thus, conducting a systematic review and meta-analysis of in vitro 5-ALA PDT experiments is meaningful and may provide opportunities to consider future perspectives in this field. We conducted a systematic literature search in PubMed to summarize the in vitro 5-ALA PDT experiments and calculated the effectiveness of 5-ALA PDT for several cancer cell types. In total, 412 articles were identified, and 77 were extracted based on our inclusion criteria. The calculated effectiveness of 5-ALA PDT was statistically analyzed, which revealed a tendency of cancer-classification-dependent sensitivity to 5-ALA PDT, and stomach cancer was significantly more sensitive to 5-ALA PDT compared with cancers of different origins. Based on our analysis, we suggest a standardized in vitro experimental protocol for 5-ALA PDT.

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Techniques for fluorescence detection of protoporphyrin IX in skin cancers associated with photodynamic therapy

Photonics and Lasers in Medicine ◽

10.1515/plm-2013-0030 ◽

2013 ◽

Vol 2 (4) ◽

Cited By ~ 37

Author(s):

Kishore R. Rollakanti ◽

Stephen C. Kanick ◽

Scott C. Davis ◽

Brian W. Pogue ◽

Edward V. Maytin

Keyword(s):

Photodynamic Therapy ◽

Fluorescence Detection ◽

Aminolevulinic Acid ◽

Protoporphyrin Ix ◽

Skin Lesions ◽

Wide Field ◽

Detection Techniques ◽

Current State ◽

Therapeutic Outcomes ◽

Skin Cancers

AbstractPhotodynamic therapy (PDT) is a treatment modality that uses a specific photosensitizing agent, molecular oxygen, and light of a particular wavelength to kill cells targeted by the therapy. Topically administered aminolevulinic acid (ALA) is widely used to effectively treat cancerous and precancerous skin lesions, resulting in targeted tissue damage and little to no scarring. The targeting aspect of the treatment arises from the fact that ALA is preferentially converted into protoporphyrin IX (PpIX) in neoplastic cells. To monitor the amount of PpIX in tissues, techniques have been developed to measure PpIX-specific fluorescence, which provides information useful for monitoring the abundance and location of the photosensitizer before and during the illumination phase of PDT. This review summarizes the current state of these fluorescence detection techniques. Non-invasive devices are available for point measurements, or for wide-field optical imaging, to enable monitoring of PpIX in superficial tissues. To gain access to information at greater tissue depths, multi-modal techniques are being developed which combine fluorescent measurements with ultrasound or optical coherence tomography, or with microscopic techniques such as confocal or multiphoton approaches. The tools available at present, and newer devices under development, offer the promise of better enabling clinicians to inform and guide PDT treatment planning, thereby optimizing therapeutic outcomes for patients.

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