OS1.3 Tumor cell-free DNA detection in CSF for primary CNS lymphoma diagnosis
| Autor: | L. Zalmaï, I Alamome, I. Harzallah, N. Zinniger, J Voirin, Guido Ahle, B. Drénou, E. Pencreach, V. Rimelen, Agathe Debliquis, A Brinet, Remy Hurstel, F Lamy |
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| Rok vydání: | 2019 |
| Předmět: |
Cancer Research
medicine.diagnostic_test business.industry Brain biopsy Primary central nervous system lymphoma medicine.disease Flow cytometry Lymphoma law.invention Oncology Cell-free fetal DNA law Biopsy Oral Presentations medicine Cancer research Neurology (clinical) business Diffuse large B-cell lymphoma Polymerase chain reaction |
| Zdroj: | Neuro Oncol |
| ISSN: | 1523-5866 1522-8517 |
| Popis: | BACKGROUND Primary CNS lymphoma (PCNSL) is a rare disease accounting for around 3% of the primary brain tumors. In the vast majority of cases, PCNSL are classified as diffuse large B-cell lymphoma according to the WHO classification. The diagnosis is based on cranial MRI, in combination with a brain biopsy. In case of classical MRI findings, the identification of lymphoma cells in the cerebrospinal (CSF) or vitreous fluid by cytology and flow cytometry might obviate brain biopsy. The presence of the somatic mutation p.Leu265Pro (L265P) in MYD88 is detectable in 50 to 80% of PCNSL, and might also be helpful to confirm the diagnosis. The aim of our study was to evaluate the contribution of a highly sensitive digital droplet PCR, targeting the mutation L265P MYD88, for the detection of tumoral circulating DNA from CSF supernatant. MATERIAL AND METHODS We identified 9 PCNSL expressing the L265P mutation at diagnosis or relapse. The mutation was found by an allele specific PCR technique either on biopsy or in CSF cells. Circulating DNA was isolated from CSF supernatant with the « QiaAmp® circulating nucleic acid» kit. The quantity of DNA collected was estimated by quantitative PCR for a reference gene (albumine) with 7900HT (Life technologies™) device. Subsequently, the L265P MYD88 mutation was quantified by digital droplet PCR Biorad™: The droplets generated were amplified by PCR, detected with the QX200 Reader, and analyzed with the QuantaSoft™ software. RESULTS The circulating DNA concentration was low, varying between 0 and 2.2 ng/mL of CSF. However, the mutation was detected in the circulating DNA from CSF supernatant in 6 out of 9 cases (66%). The fractional abundance varied from 2.6 to 85%. In 3 cases, the mutation was detected even though cytology and flow cytometry did not reveal leptomeningeal disease. For 3 other cases, the mutation was not detected: The genome copy number was below 1 copy/µL, indicating a low analytical sensitivity for theses samples. CONCLUSION This study shows that circulating DNA is present in low concentration in CSF and can be amplified by a sensitive digital PCR for the L265P MYD88 mutation. The detection of circulating PCNSL DNA in CSF is possible and might be used to improve the non-invasive diagnosis of PCNSL. It might also help to select patients for targeted therapies. |
| Databáze: | OpenAIRE |
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