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Genetic evidence implies that primary and relapsed tumors arise from common precursor cells in primary central nervous system lymphoma.

ABSTRACT: Primary central nervous system lymphoma (PCNSL) is a rare subtype of lymphoma that arises within the brain or the eyes. PCNSL recurs within the central nervous system (CNS) in most relapsed cases, whereas extra-CNS relapse is experienced in rare cases. The present study aimed at identifying the presence of common precursor cells (CPC) for primary intra- and relapsed extra-CNS tumors, and further assessing the initiating events in bone marrow (BM). Targeted deep sequencing was carried out for five paired primary intra- and relapsed extra-CNS tumors of PCNSL. Two to five mutations were shared by each pair of intra- and extra-CNS tumors. In particular, MYD88 mutations, L265P in three and P258L in one, were shared by four pairs. Unique somatic mutations were observed in all five intra-CNS tumors and in four out of five extra-CNS tumors. Remarkably, IgH clones in the intra- and the extra-CNS tumors in two pairs were distinct from each other, whereas one pair of tumors shared identical monoclonal IgH rearrangement. In a cohort of 23 PCNSL patients, L265P MYD88 mutations were examined in tumor-free BM mononuclear cells (MNC) in which the PCNSL tumors had L265P MYD88 mutations. L265P MYD88 mutations were detected by a droplet digital PCR method in nine out of 23 bone marrow mononuclear cells. These results suggest that intra- and extra-tumors are derived from CPC with MYD88 mutations in most PCNSL, arising either before or after IgH rearrangement. The initiating MYD88 mutations may occur during B-cell differentiation in BM.

SUBMITTER: Hattori K

PROVIDER: S-EPMC6317941 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: Lenalidomide is an immunomodulator agent that exhibits efficacy in multiple myeloma and haematological malignancies including refractory/relapsed diffuse large B-cell (DLBC) systemic lymphoma. METHODS: Retrospective review of PCNSL patients treated with lenalidomide at the Pitié-Salpêtrière hospital. Inclusion criteria were: 1) immunocompetent status 2) pathologically proven diagnosis of DLBC-PCNSL, 3) recurrent or refractory disease after at least two prior chemotherapy treatments, including intravenous high-dose methotrexate and cytarabine based regimens, 4) lenalidomide administered orally, at a dose of 25 mg/day on days 1-21 of a 28-days cycle. MRI scans were performed monthly. Response was evaluated according to the IPCG criteria. RESULTS: Between June 2011 and March 2013, 6 patients (4 women and 2 men) met the inclusion criteria. Lenalidomide was given as 3rd line in four patients, as 4th line in one and 5th line in one. Median age was 73.5 years (range 64-78) and median Karnofsky Performance Status was 60 (range 40-70). Two patients achieved complete response (CR). Patient 1 received a total of 9 monthly cycles of lenalidomide without any steroids and is still in remission after a follow-up of 18 months from the start of the treatment. Patient 2 achieved a CR and was off-steroids at the time of CR, but relapsed during the 3rd cycle and died after 14 weeks. Patient 3 achieved a partial response after one cycle but died suddenly during the 2nd cycle. Patients 4, 5 and 6 progressed and died 2, 5 and 6 months respectively after the start of lenalidomide. One of them who suffered from an oculo-cerebral relapse demonstrated a partial ocular response while progressing in the brain. Apart from the sudden death of unknown cause, the treatment was well tolerated. None of the patients experienced any grade III or IV toxicity. CONCLUSIONS: These results suggest that lenalidomide exhibits activity in heavily pre-treated PCNSL and is well tolerated in elderly patients. Lenalidomide efficacy on PCNSL needs to be evaluated prospectively, alone or in association with other cytotoxic agents. A phase II trial combining rituximab and lenalidomide for recurrent PCNSL is on-going in France (NCT01956695).

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Genetic evidence implies that primary and relapsed tumors arise from common precursor cells in primary central nervous system lymphoma.

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