Background/Aim: The antitumor effects of 5-aminolevulinic acid (5-ALA) radiodynamic therapy (RDT) have been demonstrated in vitro and in vivo in several malignancies. However, its application in bone and soft tissue sarcomas has not been sufficiently explored. In this study, we aimed to elucidate the efficacy of 5-ALA RDT in osteosarcoma cell lines. Materials and Methods: In vitro studies utilized human (143B) and mouse (LM8) osteosarcoma cells. Cultured cells were either untreated (control) or exposed to 5-ALA (0-1,000 μg/ml) followed by X-ray irradiation (a single dose of 5 Gy). Cell viability was measured 48 h post-irradiation. Both 143B and LM8 cells were inoculated subcutaneously into the backs of BALB/c mice. Mice were assigned to untreated (control), Rx (irradiation alone), or 5-ALA RDT groups. Mice in the Rx group received X-ray irradiation (5 Gy) after macroscopic tumor formation, while those in the 5-ALA RDT group received 5-ALA (250 mg/kg) intraperitoneally, followed by 5 Gy X-ray irradiation. The mice were sacrificed 14 days after treatment, and changes in tumor volume were evaluated. Results: In vitro, 5-ALA RDT treatment of osteosarcoma cells at 200, 500 and 1,000 μg/ml significantly inhibited cell proliferation at 48 h post-treatment, compared to control cells. In mice injected with osteosarcoma cells, the 5-ALA-RDT group showed a significant reduction in tumor volume compared to the control and Rx groups. No significant changes in body weight or abnormal behavior were observed. Conclusion: 5-ALA RDT demonstrated significant anti-tumor effects in both in vitro and in vivo osteosarcoma models. These findings suggest its potential as a therapeutic approach for osteosarcoma.
TANEMURA et al. (2026) studied this question.