MODL-08. Cellular yield and xenograft creation from probe washing after stereotactic biopsy of deep-seated CNS tumors in children

Abstract

Abstract Intracranial tumors located in otherwise difficult-to-resect regions of the brain are routinely biopsied to obtain tissue diagnosis and guide clinical decision making. However, tissue yield from these stereotactic biopsy samples is limited and leaves little remaining for research purposes or tumor banking. Given the importance of molecular diagnostics and rise of targeted therapies, research into the genetic and immune landscape of these lesions is of paramount importance, especially for inoperable and deep-seated tumors. We sought to obtain viable cellular material from otherwise discarded biopsy probes without visible tumor sample within the probe. Cells were obtained from clinically challenging pediatric tumors of the brainstem, thalamus, and pineal region by washing biopsy probes in FBS media immediately after completion of a stereotactic biopsy. The wash was then filtered and re-suspended in media before evenly distributing in a 24 well plate for culture purposes. A total of 15 samples were collected from probe washes, including 6 diffuse midline gliomas of the brain stem, 7 supratentorial diffuse midline gliomas, and 2 tumors in the pineal region. Viable tumor cells were obtained from 9/15 samples, ranging from 500 to approximately 525,000 cells per sample wash (219,222 ± 181,951). Orthotopic implantation into matching locations was completed with 7 tumor samples. Formation of a patient-derived orthotopic xenograft was confirmed in one thalamic high-grade glioma (165,000 cells). Three of the five diffuse midline gliomas of the brainstem showed early signs of tumor formation (yielding >2 million cells) and will be validated. In conclusion, viable tumor cells can be collected from biopsy probe washes after stereotactic biopsy, without visible tumor within the probe. Tumor cells can be used for patient-derived orthotopic xenograft tumor formation, which allows for new avenues in the development of animal models of difficult to resect brain tumors.