RESUMEN
Hydrogen peroxide (H2 O2 ) induces oxidative stress and cytotoxicity, and can be used for treating cancers in combination with radiotherapy. A product comprising H2 O2 and sodium hyaluronate has been developed as a radiosensitizer. However, the effects of H2 O2 on antitumor immunity remain unclear. To investigate the effects of H2 O2 , especially the abscopal effect when combined with radiotherapy (RT), we implanted murine tumor cells simultaneously in two locations in mouse models: the hind limb and back. H2 O2 mixed with sodium hyaluronate was injected intratumorally, followed by irradiation only at the hind limb lesion. No treatment was administered to the back lesion. The H2 O2 /RT combination significantly reduced tumor growth at the noninjected/nonirradiated site in the back lesion, whereas H2 O2 or RT individually did not reduce tumor growth. Flow cytometric analyses of the tumor-draining lymph nodes in the injected/irradiated areas showed that the number of dendritic cells increased significantly with maturation in the H2 O2 /RT combination group. In addition, analyses of tumor-infiltrating lymphocytes showed that the number of CD8+ (cluster of differentiation 8) T cells and the frequency of IFN-γ+ (interferon gamma) CD8+ T cells were higher in the noninjected/nonirradiated tumors in the H2 O2 /RT group compared to those in the other groups. PD-1 (programmed death receptor 1) blockade further increased the antitumor effect against noninjected/nonirradiated tumors in the H2 O2 /RT group. Intratumoral injection of H2 O2 combined with RT therefore induces an abscopal effect by activating antitumor immunity, which can be further enhanced by PD-1 blockade. These findings promote the development of H2 O2 /RT therapy combined with cancer immunotherapies, even for advanced cancers.
RESUMEN
PURPOSE: Pilocytic astrocytoma (PA) is a circumscribed low-grade astrocytic glioma, generally considered to be associated with a good prognosis. However, a subset of PA patients shows unfavorable outcomes. In this study, we retrospectively reviewed PA patients and performed further molecular analysis, such as DNA methylation profiling, to identify prognostic factors. METHODS: We analyzed 29 histologically-confirmed PA patients from a single center from 2002 to 2021 and conducted integrated molecular analyses among elderly PA patients since age was an independent prognostic factor for poor outcomes. RESULTS: The median age at diagnosis was 14 years (range 3-82 years) and 4 patients (14%) were elderly (patients ≥ 60 years old). Age over 60 was associated with poor progression-free survival and overall survival. We performed DNA methylation analysis on 2 of the 4 elderly patients. Both cases were histologically diagnosed as PA, but DNA methylation profiling revealed one as high-grade astrocytoma with piloid features (all methylation class scores were below 0.3 in both v11b4 and v12.5) and the other as glioblastoma, IDH-wildtype (score was over 0.5 in both v11b4 and v12.5), using the German Cancer Research Center methylation profiling classifiers and t-SNE analysis. CONCLUSIONS: Elderly patients with PA morphology showed unfavorable outcomes in this cohort. In those patients, further molecular analysis and DNA methylation profiling revealed the possibility of high-grade astrocytic tumors, including newly defined entities.