P13.05 Chemical Biopsy as an Alternative Sampling Method in Neurooncology

BACKGROUND

Histopathology is a gold standard for diagnostics of brain tumors but it is time consuming, demands removal of the part of the tissue what makes it highly invasive. That is why it seems to be relevant to develop new diagnostic methods addressing the abovementioned drawbacks. Ideal tool should be easy to use, as low invasive as possible and of high clinical value.

The aim of the study was to assess the usefulness of chemical biopsy based on solid phase microextraction as a sampling method for lipidomic analysis of brain tumors.

MATERIAL AND METHODS

The experiment was carried out on 38 brain tumors. Sampling was performed ex vivo, directly after removal of brain tumors. SPME fibers (coated with biocompatible extraction phase, length and diameter of the coating 7mm and 200um, respectively) were inserted into the sample without prior preparation of the tissue. Desorption of lipids was performed in isopropanol-methanol mixture. Analysis of extracts was carried out using liquid chromatography coupled to high resolution mass spectrometry.

RESULTS

Wide range of tentative lipid species was obtained in the studies. Two histologically different types of brain tumors: gliomas and meningiomas were subjected to the chemical biopsy. The results showed very good separation between the tumor types in unsupervised chemometric tests. The lipid species responsible for this separation were previously reported in the literature as cancer biomarkers. With regards to malignancy grading of gliomas the separation was notable but not as clear as between the tumor types, what is probably related to high heterogeneity of this cancerous tissue and subjectivity of histopathological analysis which were a referring point in methods comparison. Very good agreement was noted for changes in lipidome obtained by chemical biopsy and histological subtypes of gliomas. However, the most promising results showed impact of IDH1 R132H mutation on lipidome of gliomas.

CONCLUSION

Chemical biopsy seems to be useful method in lipidomics studies and for differentiation of brain tumors according their histological origin and malignancy. It also enables to find a relation between IDH1 mutation and lipidomic profile.

ACKNOWLEDGMENTS

The work was supported by the grant 2015/18/M/ST4/00059 funded by National Science Centre, Poland. The authors want to acknowledge Supelco/MilliporeSigma for the SPME probes, Thermo Fisher Scientific for the access to Q-Exactive Focus mass spectrometer, Anchem for the technical support and Shim-Pol for the access to LCMS-8060 mass spectrometer and technical support.

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