Waldenström macroglobulinemia and relationship to immune deficiency.

Primary or secondary immune deficiency (ID) is a risk factor, although rare, to develop Waldenström macroglobulinemia (WM). We aimed to better understand the incidence of this occurrence in the real-life and the outcome of either entity. We conducted a review of 194 WM in the Poitou-Charentes registry and identified 7 (3.6%) with a prior history of ID. Across the 7 WM with ID, 4 progressed to active WM disease and required treatment for WM with a median time between WM diagnosis and the first treatment of 1.5 years (range 0-3). The median time from ID to WM occurrence was 8 years (1-18). WM could develop from ID, although a rare event. Our first action was to systematically decrease immunosuppression with long-term control of ID. Half of indolent WM remained indolent despite ID and for remaining WM none appeared of poor risk WM.

Plasmacytoid dendritic cells proliferation associated with acute myeloid leukemia: phenotype profile and mutation landscape

Neoplasms involving plasmacytoid Dendritic Cells (pDCs) include Blastic pDC Neoplasms (BPDCN) and other pDC proliferations, where pDCs are associated with myeloid malignancies: most frequently Chronic MyeloMonocytic Leukemia (CMML) but also Acute Myeloid Leukemia (AML), hereafter named pDC-AML. We aimed to determine the reactive or neoplastic origin of pDCs in pDC-AML, and their link with the CD34+ blasts, monocytes or conventional DCs (cDCs) associated in the same sample, by phenotypic and molecular analyses (targeted NGS, 70 genes). We compared 15 pDC-AML at diagnosis with 21 BPDCN and 11 normal pDCs from healthy donors. CD45low CD34+ blasts were found in all cases (10-80% of medullar cells), associated with pDCs (4-36%), monocytes in 14 cases (1-10%) and cDCs (2 cases, 4.8-19%). pDCs in pDC-AML harbor a clearly different phenotype from BPDCN: CD4+ CD56- in 100% of cases, most frequently CD303+, CD304+ and CD34+; lower expression of cTCL1 and CD123 with isolated lymphoid markers (CD22/CD7/CD5) in some cases, suggesting a pre-pDC stage. In all cases, pDCs, monocytes and cDC are neoplastic since they harbor the same mutations as CD34+ blasts. RUNX1 is the most commonly mutated gene: detected in all AML with minimal differentiation (M0-AML) but not in the other cases. Despite low number of cases, the systematic association between M0-AML, RUNX1 mutations and an excess of pDC is puzzling. Further evaluation in a larger cohort is required to confirm RUNX1 mutations in pDC-AML with minimal differentiation and to investigate whether it represents a proliferation of blasts with macrophage and DC progenitor potential.

Long-term molecular remission in a patient with acute myeloid leukemia harboring a new NUP98-LEDGF rearrangement.

A large variety of molecular rearrangements of the NUP98 gene have been described in the past decades (n = 72), involving fusion partners coding for different transcription factors, chromatin modifying enzymes, as well as various cytosolic proteins. Here, we report the case of an AML-M2 patient with a variant NUP98-LEDGF/PSIP1 gene fusion (N9-L10). In this patient, three different NUP98-LEDGF fusion mRNAs were characterized due to alternative splicing in LEDGF exon 11. Targeted high-throughput sequencing revealed the presence of IDH1, SRSF2, and WT1 additional pathogenic mutations. To improve the therapeutic monitoring, quantification of NUP98-LEDGF mRNA by real-time PCR was developed. Because of poor response to conventional chemotherapy, allogeneic stem cell transplantation was performed, followed by 20 cycles of azacitidine-based preemptive treatment of relapse. More than 31 months after diagnosis, corresponding to 25 months post SCT and 4 months after the last cycle of azacytidine, the patient is in complete molecular remission (undetectable NUP98-LEDGF mRNA transcripts). This study highlights the considerable variability in breakpoint location within both NUP98 and LEDGF, associated with alternative splicing affecting LEDGF. It also emphasizes the need to fully characterize the breakpoints within the two genes and the identification of all fusion mRNAs, particularly for the development of a molecular monitoring assay. All these data seem critical for the optimal management of NUP98-LEDGF + hematological malignancies commonly associated with a poor prognosis.