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Updated: Sep 30, 2026
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
5-Aminolevulinic acid-based photodynamic detection and therapy of brain tumors (review)
Scott A Friesen1, Geir Olav Hjortland, Steen J Madsen
1Department of Pathology, The Norwegian Radium Hospital and Institute for Cancer Research, University of Oslo, Montebello, 0310 Oslo, Norway.
Abstract:
With current treatment methods the prognosis for patients with aggressive brain tumors is dismal. Treatment failure is usually due to local recurrence of tumor. Intra-operative photodynamic detection (PDD) of tumor tissue and post-surgical photodynamic therapy (PDT) of the resection cavity may be of benefit. The utility of 5-aminolevulinic acid (ALA) has been recognized in many different treatment fields over the past decade. Following administration of exogenous ALA, the endogenous photosensitizer, protoporphyrin IX (PpIX), accumulates in tumor tissue. A photodynamic effect occurs upon light activation of the target tissue. This article reviews the current preclinical and clinical studies and potential future applications of ALA and its ester-induced PpIX as a photosensitizing agent in the detection and treatment of brain tumors.
Insights
5-aminolevulinic acid (ALA) enhances protoporphyrin IX (PpIX) accumulation in brain tumors for photodynamic detection and therapy. This approach offers a promising strategy to improve treatment outcomes and reduce local recurrence in aggressive brain tumors.
Area of Science:
- Oncology
- Biochemistry
- Medical Physics
Background:
- Aggressive brain tumors have a poor prognosis, with local recurrence being a primary cause of treatment failure.
- Current treatment modalities often struggle to achieve complete tumor resection, leading to residual disease.
- Photodynamic detection (PDD) and photodynamic therapy (PDT) offer potential adjunctive strategies for improving surgical outcomes.
Purpose of the Study:
- To review preclinical and clinical studies on 5-aminolevulinic acid (ALA) for brain tumor detection and treatment.
- To evaluate the efficacy of ALA-induced protoporphyrin IX (PpIX) as a photosensitizing agent.
- To explore future applications of ALA-based PDD and PDT in neuro-oncology.
Main Methods:
- Review of existing preclinical and clinical research on ALA and its derivatives in brain tumor models and patients.
- Analysis of studies investigating the mechanism of ALA-induced PpIX accumulation in tumor tissue.
- Examination of PDD techniques for intra-operative tumor visualization and PDT protocols for post-surgical treatment.
Main Results:
- Exogenous ALA administration leads to selective accumulation of endogenous PpIX in tumor tissues.
- PpIX acts as a photosensitizer, generating cytotoxic effects upon light activation.
- Studies demonstrate ALA-PDD's utility in enhancing tumor visualization and ALA-PDT's potential in treating residual tumor cells.
Conclusions:
- ALA-induced PpIX shows significant promise as a photosensitizer for both detecting and treating aggressive brain tumors.
- PDD and PDT using ALA may improve the extent of tumor resection and reduce the risk of local recurrence.
- Further clinical investigation is warranted to establish ALA-based PDD/PDT as a standard therapeutic option for brain tumors.
