Cell free circulating tumor DNA in cerebrospinal fluid detects and monitors central nervous system involvement of B-cell lymphomas

Abstract

Cell free circulating tumor DNA in cerebrospinal fluid detects and monitors central nervous system involvement of B-cell lymphomas. Abstract word count: 250 Text word count: 2898 Tables and figures: 5 Supplemental files: 2Acknowlegements: The authors would to thank the patients diagnosed at the Vall d'Hebron University Hospital that were enrolled in the study, as well as the Cellex Foundation for providing research facilities and equipment. ABSTRACTThe levels of cell free circulating tumor DNA (ctDNA) in plasma correlate with treatment response and outcome in systemic lymphomas. Notably, in brain tumors, the levels of ctDNA in the cerebrospinal fluid (CSF) are higher than in plasma. Nevertheless, their role in central nervous system (CNS) lymphomas remains elusive. We evaluated the CSF and plasma from 19 patients: 6 restricted CNS lymphomas, 1 systemic and CNS lymphoma, and 12 systemic lymphomas. We performed whole exome sequencing or targeted sequencing to identify somatic mutations of the primary tumor, then variantspecific droplet digital PCR was designed for each mutation. At time of enrolment, we found ctDNA in the CSF of all patients with restricted CNS lymphoma but not in patients with systemic lymphoma without CNS involvement. Conversely, plasma ctDNA was detected in only 2 out of 6 patients with restricted CNS lymphoma with lower variant allele frequencies than CSF ctDNA. Moreover, we detected CSF ctDNA in 1 patient with CNS lymphoma in complete remission and in 1 patient with systemic lymphoma, 3 and 8 months before CNS relapse was confirmed; indicating that CSF ctDNA might detect CNS relapse earlier than conventional methods. Finally, in 2 cases with CNS lymphoma, CSF ctDNA was still detected after treatment even though no tumoral cells were observed by flow cytometry (FC), indicating that CSF ctDNA better detected residual disease than FC. In conclusion, CSF ctDNA can better detect CNS lesions than plasma ctDNA and FC. In addition, CSF ctDNA predicted CNS relapse in CNS and systemic lymphomas.

Circulating tumour DNA from the cerebrospinal fluid allows the characterisation and monitoring of medulloblastoma

“…As it was shown in other CNS malignancies 18,19,21,24 , we observed that CSF is a better source for ctDNA than plasma. Interestingly, we observed that high levels of CSF ctDNA before surgical resection were detected in patients at very high risk of relapse, and disease progression was observed for two of them.…”

“…Our group and others have previously reported the detection of CSF ctDNA in adult brain malignancies [18][19][20][21][22][23] . The analysis of ctDNA in the CSF better reflects the brain tumour genomic alterations than in plasma, it can be used as a molecular diagnostic tool and the dynamic changes during patient monitoring recapitulate the disease course 18,[21][22][23][24][25] .…”

Genomic Profiling of Circulating Tumor DNA From Cerebrospinal Fluid to Guide Clinical Decision Making for Patients With Primary and Metastatic Brain Tumors

“…This analysis also showed that tumor burden, measured by MRI or flow cytometry, was concordant with ctDNA-CSF levels but not plasma ctDNA. Moreover, ctDNA-CSF demonstrated an increased sensitivity for detecting CNS involvement compared to conventional cytology or flow cytometry (30).…”

“…In contrast, one can speculate that the use of steroids for PCNSL prior to ctDNA-CSF liquid biopsy may enhance the amount of ctDNA available in the CSF compartment. In one study 19 patients with B-cell lymphomas were evaluated to compare the utility of ctDNA-CSF or plasma in diagnosing CNS involvement and explore whether the analysis of ctDNA could monitor treatment response in CNS lymphomas (30). Genomic analysis of ctDNA from either CSF or plasma demonstrated readily detectable ctDNA-CSF in all 6 cases of CNS restricted lymphomas, while plasma ctDNA was only detected in 2 out of 6 cases, highlighting the sensitivity of ctDNA-CSF compared to plasma.…”

“…Further utility for CSF liquid biopsy in PCNSL includes identifying tumor recurrence, particularly in cases associated with extensive leptomeningeal involvement in which diagnosing recurrent tumor in the post-treatment setting solely by neuroimaging studies can be very difficult, often when cytologic analysis is unrevealing. Indeed, sequential ctDNA-CSF testing in patients undergoing treatment demonstrated that despite a decrease in tumor cells by flow cytometry or in some cases no detectable disease by conventional techniques, patients still harbored CNS disease when assessed with a more sensitive method (30).…”