Background Waldenström macroglobulinemia (WM) is a rare, indolent B-cell neoplasm characterized by bone marrow (BM) infiltration by lymphoplasmacytic cells producing monoclonal IgM. A distinct inflammatory subset (iWM) has recently been described, defined by persistent elevation of C-reactive protein (CRP ≥20 mg/L) in the absence of infection or autoimmune disease. This phenotype is observed in ~33% of symptomatic cases, is more frequent at relapse (42%), and remains rare in asymptomatic patients (<10%). iWM has been associated with 6q deletion, clonal hematopoiesis, and a lower frequency of CXCR4 mutations. Clinically, it correlates with shorter time to next treatment (TTNT) following immunochemotherapy, but improved TTNT in patients receiving BTK inhibitors. However, its underlying pathophysiology remains poorly understood. Methods We prospectively collected blood and BM samples from 36 individuals with symptomatic WM. Based on CRP levels, patients were classified as having iWM (n = 20, median age 76 years) or non-inflammatory WM (nWM, n = 16, median age 74 years). Patients with elevated IgM levels but concurrent malignancies or inflammatory disorders—including Schnitzler syndrome—were excluded. Ederly healthy donors (HD, n = 13, median age 58 years) served as controls. Serum concentrations of inflammatory cytokines, including IL-1β, IFN-α2, IFN-γ, TNF-α, MCP-1, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-18, IL-23, and IL-33, were measured using multiplex ELISA. High-dimensional immune profiling by 40-marker spectral flow cytometry and single-cell RNA sequencing (scRNA-seq) were performed on peripheral blood to characterize immune cell populations. Results iWM was not associated with tumor burden at the symptomatic phase, as assessed by IgM levels and BM infiltration. However, plasma cytokine analysis at steady state revealed significantly higher levels of inflammasome-related cytokines in iWM compared to nWM and HD. IL-1β showed the strongest difference, with median concentrations threefold higher in iWM (2630 fg/mL) compared to nWM (976 fg/mL, p = 0.02). IL-18 levels were also significantly higher in iWM (1205 pg/mL) versus nWM (500 pg/mL, p = 0.006). IL-6 levels were elevated in iWM (median 37 pg/mL vs 11 pg/mL) but did not reach statistical significance (p = 0.11). No correlation with age was observed for IL-1β (r = 0.14, p = 0.31) or IL-18 (r = 0.05, p = 0.77), and cytokine levels were similar between nWM and healthy donors. In peripheral blood, spectral cytometry (n = 7 per group; 100,000 cells/patient) and scRNA-seq (n = 3 per group; 43,000 cells total) revealed a higher proportion of intermediate and non-classical monocytes in iWM compared to nWM (p < 0.001). Overall, IL-1β expression was significantly increased in iWM relative to both nWM and HD (p < 0.001), with monocytes identified as the principal source. Subclustering revealed a population of cytokine-producing classical monocytes in iWM as the main IL-1β producers, with upregulation of inflammasome-related genes compared to their counterparts in nWM. In the bone marrow (n = 4 per group; 100,000 cells/patient), spectral cytometry showed an increased abundance of monocytes/macrophages in iWM compared to nWM. Mast cell density did not differ between groups. Discussion iWM represents a biologically distinct inflammatory subset of WM, independent of tumor burden, and seems to be associated with alterations in the immune microenvironment. Cytokine-producing monocytes, more transcriptionally active in iWM and functionally suppressed in nWM, may be key contributors to the inflammatory profile. Given the role of BTK in inflammasome regulation—and the superior clinical responses observed in iWM under BTK inhibitor therapy—these findings highlight potential therapeutic strategies targeting IL-1β signaling and monocyte–B-cell interactions. Additional investigations are ongoing, including BM scRNA-seq and monocyte stimulation assays, to further characterize the inflammatory mechanisms underlying iWM.

Human parainfluenza virus type 3 (HPIV-3) can be responsible for mild to severe respiratory infections and hospital epidemics. We investigated an outbreak in a hematology unit. Respiratory viruses were screened using multiplex PCR. HPIV-3 quantification and whole-genome sequencing were performed on HPIV-3 positive respiratory samples. Clinical characteristics, infection progression, incidence rates of respiratory viruses within the hospital and detection of respiratory viruses were documented, along with the reinforcement of infection prevention and control (IPC) measures implemented. Between November 2022, and January 2023, HPIV-3 was identified in 20 of 113 hematology patients (17.7%), of whom 80% had multiple myeloma. A majority of HPIV-3-positive patients developed pneumonia (60%), and mortality was notably higher (35%) compared to patients who were negative (3%, p < 0.0001). Respiratory HPIV-3 viral loads were similar between patients with and without pneumonia. In parallel, HPIV-3 incidence in the hospital overall was lower than in the hematology unit (p < 0.0001). Air virus screening showed the detection of HPIV-3 in the air in different areas, and whole-genome sequencing confirmed the circulation of a single HPIV-3 strain. Strengthened IPC measures were associated with the containment of the outbreak. HPIV-3 has high epidemic potential in patients with multiple myeloma and causes severe infections. Our findings highlight the need for routine HPIV-3 testing in hematology units.

Le syndrome d’hyperviscosité sérique est une urgence médicale résultant d’une hyperprotidémie et se manifeste cliniquement par une triade de symptômes : hémorragies muqueuses, troubles visuels et troubles neurologiques, ces derniers survenant dans les cas les plus graves. Le diagnostic repose avant tout sur l’observation clinique et peut être rapidement confirmé par un examen du fond d’œil en urgence. En cas de forme symptomatique, le traitement principal est basé sur les échanges plasmatiques. Les analyses biologiques sont cruciales pour identifier l’étiologie de ce syndrome, qui est fréquemment associée à la maladie de Waldenström (caractérisée par un pic d’IgM), au myélome multiple et aux cryoglobulinémies. Afin de prévenir les récidives, un traitement spécifique de la cause sous-jacente est instauré après la phase initiale d’échanges plasmatiques.

ABSTRACT:Inflammatory form of Waldenström macroglobulinemia (iWM) predicts outcomes after immuno-chemotherapy and Bruton tyrosine kinase inhibitors, but its origin is unknown. Here, we unravel increased clonal hematopoiesis in patients with iWM (61% vs 23% in noninflammatory WM), suggesting a contribution of environmental cells to iWM.

BACKGROUND:Scleromyxedema (SM) is a rare skin disorder related to monoclonal gammopathy. High dose intravenous immunoglobulins (HDIVIg) are usually used as a frontline therapy with initial efficacy. However, some patients evolve with relapse, refractory state or severe extra-cutaneous complications such as dermato-neuro syndrome (DNS) or cardiac involvement. The objective of the study is to evaluate the use of anti-plasma cell treatment in these patients in order to obtain a deep and durable dermatological and haematological response. METHODS:We report here eight patients treated with HDIVIg together with anti-plasma cell therapy including: lenalidomide and dexamethasone (n = 5); bortezomib, cyclophosphamide and dexamethasone (n = 1); daratumumab, lenalidomide and dexamethasone (n = 2). RESULTS:Combination of HDIVIg with a treatment targeting the monoclonal component led to a high level of haematological remission and drastically improved skin response with an acceptable safety profile in all patients. Moreover, HDIVIg was reduced and stopped in 4 of the 7 patients who achieved complete remission. CONCLUSIONS:The association of lenalidomide and dexamethasone with HDIVIg could improve the treatment of relapsed or severe SM.

Introduction Le scléromyxoedeme (SM) est une mucinose primaire systémique très fréquemment associée à une gammapathie monoclonale appartenant au spectre des gammapathies monoclonales de signification clinique et cutanée. Les immunoglobulines intra-veineuses (IgIV) données à 2g/kg/cure mensuelle sont le traitement de première intention. Néanmoins, certains patients rechutent ou sont dépendants de fortes doses d’immunoglobulines, ou présentent des complications sévères extra-cutanées comme le dermato neuro-syndrome ou les atteintes cardiaques (cardiomyopathie hypertrophique).L’objectif de cette étude est d’évaluer l’efficacité du traitement anti-plasmocytaire chez ces patients afin d’obtenir une réponse dermatologique et hématologique profonde et durable. Patients et méthodes Nous rapportons une série de huit patients atteints de SM réfractaires ou présentant une complication sévère extra-cutanée, ayant reçu des IgIV associées à un traitement anti-plasmocytaire.La réponse hématologique est basée sur l’EPS (électrophorèse des protéines sériques) et l’immunofixation : RP (réponse partielle) diminution de plus de 50 % du pic monoclonal, TBRP (très bonne réponse partielle) : diminution de plus de 90 % du pic monoclonal, RC (rémission complète) absence de pic à l’EPS et immunofixation négative.La réponse dermatologique repose sur le score d’évaluation clinique générale subjective PGA (physician global assessment) allant de 0 à 2 (0=pas d’amélioration ; 1=amélioration partielle ; 2=amélioration complète). Résultats La combinaison des traitements par IgIV données à la dose initiale de 2g/kg/cure et le traitement anti-plasmocytaire (lénalidomide et dexaméthasone (n=5), bortézomib, cyclophosphamide et dexaméthasone (n=1) ; daratumumab, lénalidomide et dexaméthasone (n=2)) permet d’obtenir une très bonne réponse dermatologique et hématologique avec une bonne tolérance : PGA=2 (6/7 patients), rémission complète hématologique (2/8), très bonne réponse partielle (4/8), réponse partielle (2/8). De plus, les IgIV ont pu être diminuées puis arrêtées chez 4 patients sur 7 ayant obtenu une réponse hématologique et dermatologique. Discussion Le ciblage du clone plasmocytaire et en particulier l’association lénalidomide et dexaméthasone associée aux IgIV permet d’obtenir une réponse durable et profonde chez les patients avec un scléromyxoedème en rechute ou réfractaire aux IgIV ou avec une atteinte extra-cutanée sévère. Conclusion Le traitement anti-plasmocytaire permet d’obtenir un meilleur contrôle de la maladie et de réduire puis d’arrêter les IgIV et les corticoïdes dès que le patient est en réponse complète hématologique et dermatologique.

Seric hyperviscosity syndrome is a medical emergency linked to hyperproteinemia. The clinical diagnosis hinges on a triad of symptoms: mucosal hemorrhages, visual disturbances, and neurological disorders, observed in the most severe cases. Diagnosis is swiftly confirmed through an urgent fundoscopic examination. Therapeutic plasma exchange is the primary treatment for severe cases or following confirmation by fundoscopy. Laboratory tests predominantly identify the syndrome's etiology, with Waldenström's macroglobulinemia (characterized by a marked IgM peak) being the most common cause, followed by multiple myeloma and cryoglobulinemias. To prevent recurrence, targeted treatment of the underlying cause is implemented following plasma exchange sessions.

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L’amylose AL systémique peut toucher l’ensemble des organes à l’exception du système nerveux central, avec un spectre de manifestations extrêmement polymorphe. L’atteinte cutanéo-muqueuse peut mener au diagnostic avec des signes cliniques devant être connus et recherchés (macroglossie, purpura par fragilité capillaire). Nous décrivons un cas d’amylose AL révélé par des bulles hémorragiques et un purpura intrabuccal isolé et soulignons l’importance de la biopsie avec coloration au rouge Congo. Nous rapportons le cas d’une patiente de 75 ans, suivie pour un cancer du sein en rémission, qui présentait depuis un an des épisodes stéréotypés et évoluant par poussées de bulles hémorragiques intrabuccale. Il n’existait pas d’atteinte muqueuse ou cutanée associée. L’ensemble du bilan étiologique non invasif était négatif (auto immunité dont anticorps des dermatoses bulleuses auto-immunes, explorations microbiologiques, coagulation dont facteur X). Une première biopsie était aspécifique avec une légère hyperplasie vasculaire sans dépôts. Le diagnostic de stomatite bulleuse hémorragique était évoqué cliniquement. La découverte d’un pic IgG kappa à 10 g/L avec excès de chaînes légères (CLL kappa à 871 mg/L) faisait réaliser un myélogramme confirmant le diagnostic de myélome indolent (10 % de plasmocytes dystrophiques, absence de critères CRAB). Une relecture histologique était alors demandée, avec une coloration au rouge Congo montrant des dépôts amyloïdes. L’immunohistochimie confirmait la présence de chaines légères kappa. Le bilan d’atteinte d’organe faisait poser le diagnostic d’amylose AL cardiaque et probablement rénale associée. Un traitement par daratumumab – lénalidomide – dexaméthasone était débuté, avec un ajout de bortézomib à 4 mois devant une réponse insuffisante. Il n’existait à ce jour qu’une réponse partielle sur l’atteinte bulleuse intrabuccale. L’atteinte de la muqueuse buccale dans l’amylose AL est bien décrite, allant de la macroglossie à la sécheresse buccale, en passant par l’agueusie. Par ailleurs, le risque hémorragique est également bien documenté, avec des mécanismes physiopathologiques multifactoriels (fragilité capillaire, déficit en facteur X ou plus rarement V ou IX, augmentation de la fibrinolyse). Il s’agit cependant du premier cas décrit d’atteinte bulleuse de la muqueuse buccale isolée dans le cadre d’une amylose AL, situation tout à fait exceptionnelle. L’amylose AL bulleuse localisée à la sphère oro-pharyngée est une entité rarissime. Cette observation incite en cas de bilan étiologique négatif de bulles hémorragiques intrabuccale à pratiquer une coloration par le rouge Congo.

Introduction Several powerful agents have been validated in multiple myeloma (MM) in the last decades: proteasome inhibitors (PI), immunomodulators (IMID), monoclonal antibodies against CD38, and immunotherapy targeting T cells cytotoxicity. Despite the improvement of therapy, relapses always occur, leading to relapse/refractory MM (RRMM) associated with dismal outcomes. At each relapse, treatment choice becomes a more and more complex decision. With the recent validation for combination in newly diagnosed MM of Daratumumab/Bortezomib/Lenalidomide and/or Dexamethasone (D) association, Carfilzomib (K), a second-in class PI and Pomalidomide (P), a second-in class IMID seems an exciting association to treat RRMM. Here, we analyzed our real-life experience of KPD in RRMM to evaluate the time to the next treatment (TTNT) in patients at Saint Louis Hospital, Paris. Methods We performed a real-life study of RRMM patients who received KPD triplet (eligible if they received one complete cycle of KPD without other treatments) from 2016 till June 2023. Responses were assessed as per the International Myeloma Working Group. The study was conformed to the Declaration of Helsinki. Results Twenty-seven patients were treated with KPD for RRMM in our center. The median age was 64 years (IQR 55-69 years), with a male ratio of 67% (n=18). The subtype of immunoglobulin was IgG (44%), followed by IgA (40%). Among the 26 (96%) patients with FISH available at relapse and before KPD, del 17p, t(4;14), gain 1q, and del 1p were present in 4 (15%), 7 (27%), 8 (31%) and 4 (15%), respectively. Nine (35%) had high-risk cytogenetics (del 17p or/and t(4;14)). At the first line, 15 (55%) received intensive options with autologous stem cell transplantation (ASCT). The first line was composed of Velcade (70%), anti-CD38 antibodies (19%) or IMID (78%: 48% Lenalidomide and 30% Thalidomide) with Dexamethasone. None had prior exposition to Carfilzomib, but three patients (11%) had exposition to Pomalidomide. Three (11%) patients had extra-medullary disease before KPD. The median number of prior lines of chemotherapy was 2 (IQR 1-3), including 70% of the patients who received KPD at the second or third line. Fifteen (56%) patients were refractory to Bortezomib, 25 (93%) to Lenalidomide, 22 (82%) to anti-CD38 antibodies and one (4%) to Pomalidomide. The median number of KPD cycles was 4 (IQR 2-10). All patients received a weekly dose of Carfilzomib except one who received a bi-weekly dose. Twenty (74%) patients started pomalidomide at 4 mg, one (4%) at 3 mg and 6 (22%) at 2 mg from day 1 into day 21. ORR was 66%: CR (n=1, 4%), VGPR (n=7, 26%) and PR (n=10, 37%). Two (8%) patients had progressive disease at the first evaluation. The median time to treatment response was 3 months (IQR 2-6). The median duration of response was 1 year (95%CI 0.5-NA years). Among the 3 patients with prior exposition to Pomalidomide, two had a response to KPD: one PR and one VGPR. The patient refractory to Pomalidomide had stable disease after 2 cycles and then quickly progressive disease. Concerning the side effects of KPD, cardiac toxicity from carfilzomib was reported, including 2 (8%) ischemic cardiac events, 1 (4%) transient ischemic attack, and 3 (11%) induced hypertension. Also, 2 (8%) patients experimented with acute renal failure and one (4%) with thrombotic microangiopathy (TMA) was observed. Three (11%) patients required hospitalization for infections (one candidemia, one flu linked to the TMA episode and one without documentation). At a median follow-up of 1.6 years (0.7-3 years), the median TTNT and overall survival (OS) was 0.7 years (95%CI 0.4-NA years, figure A) and 2 years (95%CI 0.7-NA years, figure B). The mortality rate was 44% (n=12). Most patients had active myeloma at death (11 of 12 with 10 deaths related to myeloma and one from infection), and one died of infections. Ten (37%) patients continued the KPD combination at the last follow-up including two (8%) patients in a maintenance phase, including 1 for Pomalidomide and Dexamethasone after 15 cycles and one for Pomalidomide alone after 22 cycles of KPD. Conclusion In high-risk RRMM especially refractory to anti-CD38 antibodies and lenalidomide, KPD seems to be a valid option in early relapse. Second and third centers will be included in this real-life cohort of RRMM receiving KPD to increase the power of this analysis.

Teclistamab shows promising results in R/R AL amyloidosis, with VGPR or better in 88% of patients and involved FLC < 10 mg/L in 76%. We observed a 35% rate of severe infections and no cardiac or kidney related events.

Background Autoimmune and inflammatory diseases (AID) are associated with myeloid malignancies[1], and include both organ-specific diseases and systemic inflammatory disorders. While the occurrence of associated AID reaches up to 15-20% in myelodysplastic neoplasms (MDS) patients[2,3], its prevalence in the context of myeloproliferative neoplasm (MPN) remains unknown. In patients with a history of AID, the risk of developing MPN was increased[4], suggesting a correlative link between the two disorders, but data regarding the characterization of AID in MPN patients remain scarce and the lack of studies prevents from identifying potential risk traits that may underline a common physiopathology. Objectives We conducted a single center retrospective study to describe the prevalence, clinical and biological features of AID in MPN patients. We also reported the mutational landscape of MPN with associated AID, along with its prognostic impact. Methods All patients with a diagnosis of Philadelphia-negative MPN according to the World Health Organization’s criteria, followed between January 2011 and January 2021 in our center were included. Clinical and biological characteristics at the time of diagnosis and follow-up were collected. Next-generation targeted sequencing was performed targeting a panel of 36 genes involved in myeloid malignancies. AID diagnosis was based on recommended international criteria specific to each AID. Patients with interferon-alpha-induced AID were excluded from this study. Results A total of 1541 MPN patients were included, including 95 (6%) patients with AID who were compared to the remaining 1446 (94%) patients without AID. Median age was 51.6 [6.6; 98.3] years at MPN diagnosis in the whole cohort. Female patients were predominant within the AID group (62 (65%) versus 773 (54%), p=0.03). Within the AID cohort, a total of 103 diagnoses of AID were reported in 95 patients, including 48 organ-specific AID (47%) (autoimmune hypothyroidism (n=33), inflammatory bowel diseases (IBD, n=7), neuroinflammatory disorders (n=4), autoimmune cytopenia (n=2), glomerulonephritis (n=1) and pernicious anemia (n=1)), 13 inflammatory arthritis (13%), 9 connective tissue diseases (9%), 9 dermatosis (9%), 6 systemic vasculitis (6%) and 18 unclassified AID (17%). Molecular sequencing was performed in 998/1541 (65%) patients and the prevalence of driver and additional mutations did not differ between the MPN with or without AID. The prevalence of TET2 mutations was higher in the AID cohort (21/65, 32% versus 208/993, 22%), although not reaching statistical significance (p=0.08). After a median follow-up of 8.3 IQR[3.7-14.3] years, the association with AID did not impact overall survival (p= 0.67), MDS/AML transformation free survival (p=0.37) or secondary myelofibrosis-free survival (p=0.91). Conclusion Our data suggest that the prevalence of AID is similar in MPN patients to that of the general population, and that the distribution and presentation of AID in MPN patients is also similar. TET2 mutations are highly prevalent in MPN patients with AID suggesting a shared physiopathology. Additional mechanistic studies are needed to further decipher a potential TET2-mediated common physiopathology. The association with AID did not impact MPN patients’ outcome. References [1]Barcellini, W. et al. Increased prevalence of autoimmune phenomena in myelofibrosis: Relationship with clinical and morphological characteristics, and with immunoregulatory cytokine patterns. Leukemia Research37, 1509–1515 (2013). [2]Mekinian, A. et al. Systemic inflammatory and autoimmune manifestations associated with myelodysplastic syndromes and chronic myelomonocytic leukaemia: a French multicentre retrospective study. Rheumatology (Oxford) 55, 291–300 (2016). [3]Zhao, L.-P. et al. Genomic landscape of MDS/CMML associated with systemic inflammatory and autoimmune disease. Leukemia (2021). [4]Kristinsson, S. Y. et al. Autoimmunity and the risk of myeloproliferative neoplasms. Haematologica95, 1216–1220 (2010). Acknowledgements The authors thank the clinical care team of the Comprehensive Myeloproliferative neoplasms Center for samples and data collection, and the staff of the cellular biology laboratory for excellent technical assistance. The authors also thank the French Intergroup for Myeloproliferative neoplasms (FIM) for insightful discussions. Disclosure of Interests None Declared.

Hyperviscosity syndrome (HVS) is a rare complication of newly diagnosed multiple myeloma (NDMM) related to high tumour burden. Studies about the prognosis of HVS in modern-era therapy for NDMM are missing. We investigated a retrospective cohort study of NDMM with HVS between 2011-2021. Thirty-nine NDMM patients with HVS were included. HVS presentation was heterogeneous, with asymptomatic, mild, and neurological forms in 23%, 59%, and 18% of cases, respectively. No thrombosis or major bleeding was observed. Therapeutic plasma exchanges were used in 92% of patients, which were effective and well tolerated. No rebound effect was observed. All patients except one had at least one CRAB criterion. Most of the patients received bortezomib and high-dose steroids (95%) associated with an immunomodulatory drug (43%) or alkylating agents (42%). HVS in NDMM patients had dismal overall survival matched to multiple myeloma patient controls (without HVS) in our center (median: 3.6 vs. 7.7 years, p=0.01), as confirmed by multivariate analysis. Early deaths (in the first two months) occurred in 21% of older patients (>65 years). HVS in NDMM patients is a rare but life-threatening complication associated with high lethality in older patients and be a potential dismal prognosis factor in the modern treatment era.

Introduction Waldenström's macroglobulinemia (WM) is an indolent lymphoma with medullary infiltration by a lymphoplasmacytic clone associated with an immunoglobulin M paraprotein. Some patients diagnosed with WM present a concomitant inflammatory syndrome: increased C-reactive protein (CRP) levels, fever, recurrent night sweats, anorexia. These patients were usually referred as inflammatory WM despite no definition has been established. Here, we describe clinical and biological characteristics of inflammatory WM patients, response to treatment, survival and discuss pathogenesis hypotheses. Methods In this descriptive retrospective study, we included WM patients followed at Saint-Louis hospital between 2007 and 2019 with WM diagnosis fulfilling the World Health Organization's criteria, with medullary infiltration proven by bone marrow biopsy or aspiration examination and monoclonal M paraprotein, associated with a biological inflammatory syndrome with or without clinical inflammatory signs. Inflammatory WM diagnosis was retained in the absence of differential diagnoses for the inflammatory syndrome such as cancer, infection, autoimmune or inflammatory diseases, using complete blood workup, PET and body scanner. Results Two-hundred and forty-two patients were included: 67 of inflammatory phenotype (28%), 166 non-inflammatory (68%) and 9 with inflammatory syndrome of unknown origin (4%). Describing inflammatory WM, diagnoses were made between 1985 and 2018, 50% after 2007. At treatment initiation, median age was 69 years (range 45-94), monoclonal IgM median value was 24.9 g/L (4.8-77.3) (Table 1). Median CRP was 40.5mg/L (IQR 23.8-64.8). CRP was correlated with fibrinogen (r =0.53, 95% confidence interval (CI) 0.18-0.76, p=0.006) and inversely correlated with albuminemia (r=-0.65, CI -0.82- -0.39, p < 0.001). Mean medullary infiltration was 50%. Three of 35 patients with avalaible karyotype had 6q deletion. Only 12 patients had medullary molecular analysis: 9 of them harboured MyD88 L265P mutation, 2 p53 mutations and none CXCR4 WHIM mutation. Five cryoglobulin tests were positive, Coombs test positive for 3 patients and anti-MAG antibodies positive for 2. Indications for front-line therapy were cytopenias in 44 patients (88%), inflammatory syndrome for 20 (40%), systemic symptoms in 15 (30%), tumoral syndrome in 10 (20%) and hyperviscosity syndrome in 3 (6%). Sixty-two patients were treated, at front-line 60% received rituximab-based therapy and 39% monotherapy. Overall response rate was 84%. Inflammatory and hematological response were statistically correlated (OR 13.8, CI 2.07-74.6, p = 0.005). Median follow-up was 12.6 years (IQR 7.0-22.8). Median progression-free survival (PFS) after front-line therapy was 32 months and estimated PFS was 68% (CI 55-78) at 10 months, 59% (CI 46-70) at 20 months and 30% (CI 19-42) at 5 years. Overall survival (OS) for inflammatory and non-inflammatory WM patients were not significantly different (median OS 14.0 and 16.4 years, respectively, c2 0,14, p=0,71, Figure 1). At 5 years, estimated OS was 85% (CI 71-93) inflammatory patients and 84% (CI 75-90) for non-inflammatory, at 10 years 66% (CI 48-79) and 70% (CI 58-79). Three patients were secondarily diagnosed with diffuse large B-cell lymphoma (DLBCL). Conclusions We reported 67 WM patients with inflammatory phenotypes, representing a third of WM patients in our cohort. Compared with literature, their clinical and biological characteristics do not differ from non-inflammatory WM patients, as well as response to treatment and PFS. There is no excess of transformation into DLBCL. Our inflammatory and non-inflammatory cohorts show no difference in terms of OS. Inflammatory response is strongly correlated with hematological response. Non-decrease of CRP level during treatment and increase of CRP during follow-up in inflammatory WM patients should be a warning sign for refractory disease or relapse. Further studies are needed to better delineate this sub-group of patients and explore its pathogenesis. Studying medullary cytokinic environment, WM cells, tumoral microenvironment and M paraprotein contributions could elucidate the underlying pathophysiological mechanisms involved. Disclosures Thieblemont: Roche, Hospita: Research Funding; Roche, Amgen, Kyte Gilead, Celgene, Abbvie, Novartis, Cellectis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Cellectis: Speakers Bureau.

Waldenström's macroglobulinaemia (WM) is a B-cell neoplasm resulting from bone marrow lymphoplasmacytic infiltration and monoclonal IgM secretion. Some patients present concomitant inflammatory syndrome attributed to the disease activity; we named this syndrome inflammatory WM (IWM). We retrospectively analysed all WM patients seen in a single tertiary referral centre from January 2007 to May 2021, and after excluding aetiologies for the inflammatory syndrome using a pertinent blood workup, including C-reactive protein (CRP), and imaging, we identified 67 (28%) IWM, 166 (68%) non-IWM, and nine (4%) WM with inflammatory syndrome of unknown origin. At treatment initiation, IWM patients had more severe anaemia (median Hb 90 vs 99 g/l; p  < 0.01), higher platelet count (median 245 vs 196 × 109/l; p  < 0.01) and comparable serum IgM level (median 24.9 vs 23.0 g/l; p  = 0.28). A positive correlation was found between inflammatory and haematological responses (minimal response or better) (odds ratio 32.08; 95% confidence interval 8.80–98.03; p  < 0.001). Overall survivals (OS) were similar (median OS: 17 vs 20 years; p  = 0.11) but time to next treatment (TNT) was significantly shorter for IWM (TNT1: 1.6 vs 4.8 years, p  < 0.0001). IWM mostly shared the same presentation and outcome as WM without inflammatory syndrome.

Germinal centers (GCs) are anatomic structures where B cells undergo affinity maturation, leading to production of high-affinity antibodies. The balance between T follicular helper (TFH) and regulatory (TFR) cells is critical for adequate control of GC responses. The study of human TFH and TFR cell development has been hampered because of the lack of in vitro assays reproducing in vivo biology, along with difficult access to healthy human lymphoid tissues. We used a single-cell transcriptomics approach to study the maturation of TFH and TFR cells isolated from human blood, iliac lymph nodes (LNs), and tonsils. As independent tissues have distinct proportions of follicular T cells in different maturation states, we leveraged the heterogeneity to reconstruct the maturation trajectory for human TFH and TFR cells. We found that the dominant maturation of TFR cells follows a bifurcated trajectory from precursor Treg cells, with one arm of the bifurcation leading to blood TFR cells and the other leading to the most mature GC TFR cells. Overall, our data provide a comprehensive resource for the transcriptomics of different follicular T cell populations and their dynamic relationship across different tissues.

Les maladies auto-immunes et inflammatoires (MAI) sont associées à un sur-risque de survenue de néoplasies myéloprolifératives (NMP) [1]. Chez les patients présentant un syndrome myélodysplasique (SMD) ou une leucémie myélomonocytaire chronique (LMMC), les mutations des régulateurs épigénétiques TET2 et IDH1/2 étaient significativement plus fréquentes chez les patients porteurs de MAI comparativement à une cohorte témoin de patients SMD/LMMC sans MAI [2]. Dans le contexte des NMP, le phénotype des MAI associées et leur statut mutationnel ont été peu décrits. Les objectifs de notre étude étaient de décrire les caractéristiques cliniques et génétiques des patients présentant une NMP avec une MAI et d’évaluer leur impact pronostique. Dans notre centre, 1541 patients ont été diagnostiqués d’une NMP selon les critères OMS, entre janvier 2011 et janvier 2021. Des analyses moléculaires par séquençage haut débit (NGS) ciblant un panel de 36 gènes mutés dans les NMP ont été réalisées pour 998 d’entre eux, au diagnostic ou durant le suivi. Tous les cas de MAI ont été revus par un interniste et les diagnostics évalués selon les critères internationaux correspondants. Les diagnostics de MAI post-interféron ont été exclues. Notre cohorte comprenait 522 (34 %) polyglobulie de Vaquez (PV), 709 (46 %) thrombocytémie essentielle (TE) et 229 (15 %) myélofibrose primitive (MFP). Cent (6.6 %) patients présentaient une MAI associée et les 1441 patients restants ont constitué notre population témoin. L’âge médian de nos patients dans la cohorte globale était de 54 ans [IQR 40.4–63.2] et il y avait une prédominance de femmes dans le groupe avec MAI associée (66 (66 %) versus 769 (53 %), p = 0.019). Il n’y avait pas de différence significative entre les 2 groupes concernant les sous-types de NMP, les mutations « driver » (JAK2, MPL et CALR) ou encore l’hémogramme au diagnostic des NMP. L’incidence d’épisodes thrombotiques ou hémorragiques était aussi similaire dans les 2 groupes (44 (44 %) versus 564 (39 %), p = 0.356). Le diagnostic de MAI était antérieur à celui de NMP dans 34 % des cas, concomitant dans 12 % et ultérieur dans 31 %. Sur les 100 MAI, 45 était des maladies auto-immunes spécifiques d’organe, principalement des thyroïdites auto-immunes, 13 rhumatismes inflammatoires chroniques, 9 connectivites, 8 dermatoses inflammatoires, 7 vascularites et 18 inclassés. Au total, 70 % des maladies auto-immunes remplissaient leurs critères de classification. Parmi les patients ayant bénéficié d’une analyse moléculaire, 62 % avaient une mutation additionnelle à la mutation « driver ». Les mutations de TET2 étaient plus fréquemment retrouvées chez les patients avec une MAI associée (24 (34 %) versus 205 (22 %), OR = 1.84 95 %CI [1.08–3.07], p = 0.028), mais elle n’était pas associée à un sous-type de MAI particulier. Il existait une tendance à une surreprésentation des mutations IDH1/2 dans le groupe MAI (4 (6 %) versus 27 (3 %), OR = 2.02 95 %CI[0.74–5.51], p = 0.27), bien que non statistiquement significatif. Nous n’avons pas retrouvé d’autres mutations de facteurs épigénétiques, de transcription, d’épissage ou de mutation à haut risque moléculaire, associées préférentiellement au groupe NMP avec MAI associée. Après un suivi médian de 8.3 ans dans la cohorte globale, la présence d’une MAI n’avait pas d’impact défavorable sur la survie globale (p = 0.82), ni sur la survenue de myélofibrose secondaire (p = 0.98), ou la survenue de transformation en SMD/LAM (p = 0.53). Au sein de cette large cohorte rétrospective de NMP décrite sur le plan clinique et moléculaire, la prévalence de MAI est de 6.6 %, similaire à celle de la population générale. Une sur-prévalence de la mutation de TET2 a été mise en évidence dans le groupe de patients présentant une MAI associée. Nos résultats suggèrent une susceptibilité génétique commune, secondaire à la mutation de régulateur épigénétique comme TET2, potentiellement responsable des phénotypes inflammatoire et hématologique.

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy (TMA) syndrome (Kremer et al. 2017). TTP typically includes severe thrombocytopenia, microangiopathic hemolytic anemia (MAHA) with schistocytes and organ manifestations secondary to microvascular thrombosis (neurological symptoms, acute kidney injury (AKI), myocardial infarction), associated with severe functional deficiency of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13) (Joly et al, 2019). The majority of acquired TTP in adults are related to an auto-immune disorder where anti-ADAMTS13 antibodies cause that deficiency and subsequent platelet adhesion and aggregation.Bacterial infections, autoimmune diseases, pregnancy, drugs, HIV infection, cancers, organ or HSC transplantation are the most frequent clinical conditions associated with TTP (Joly et al, 2019).Lenalidomide, an immunomodulatory drug, is a treatment of multiple myeloma (MM), myelodysplastic syndromes. Most frequent adverse effects are cytopenias, infections and thrombosis. We report 3 new cases of acquired autoimmune TTP in patients treated with Lenalidomide. A 69-year-old female, with a 10-year history of MM (multiple myeloma) IgG kappa, received lenalidomide (10 mg daily) plus dexamethasone (20 mg weekly) for a second relapse. In April 2017, while in partial response after five months of treatment, she developed dizziness, ataxia, visual field abnormalities and left upper limb dyskinesia. She presented with haemoglobin 80 g/l, platelets 4 × 109/l, high reticulocyte count 180 × 109/l, elevated LDH 1200 UI/l, decreased haptoglobin, no schistocytes on blood smears and a creatinine level of 11 mg/l. A direct antiglobulin test was negative and complement (C3, C4 and CH50) levels were normal. A brain MRI showed several cortical and non-cortical cerebrovascular infarctions. ADAMTS13 activity was undetectable at <5%, with presence of anti-ADAMTS13 IgG (>100 U/ml). Lenalidomide was stopped and the patient benefited from 16 therapeutic plasma exchanges (TPE), with methylprednisolone 1 mg/kg daily, tapered over a month, resulting in a rise of the platelet count till 70 × 109/l, and a normalisation of LDH levels ‒ neurological symptoms progressively disappeared. Ten months later, the platelet count remained stable at 67 × 109/l with a normal ADAMTS13 activity (88%). She is currently treated with bortezomib, cyclophosphamide and dexamethasone in a partial haematological response. A 70-year-old woman was treated with lenalidomide (10 mg daily) from June 2014 for refractory anaemia, 5q-syndrome. After three months of treatment, she presented with fever, abdominal pain and right upper limb paresis, haemoglobin 40 g/l, platelets 2 × 109/l, high LDH levels (1560 U/l), low haptoglobin, the presence of schistocytes on blood smear, oliguric AKI (17 mg/l), and a high level of troponin. ADAMTS13 activity was undetectable at <5%, associated with anti-ADAMTS13 IgG (190 U/ml). CT scans revealed multiple ischemic events: infarctions of cerebrum, cerebellum and brainstem, renal, splenic and colic infarctions. A total of 15 TPE were performed and after the fourth the patient experienced improved motor function. She also received methylprednisolone initially of 1 mg/kg, tapering over two weeks after TPE discontinuation, and four infusions of rituximab 375 mg/m2. After 12 months, ADAMTS13 activity was at 61%, with 165 × 109/l platelets. The patient then developed secondary myelofibrosis and died from its complications. A 71-year-old male with a five-year history of IgG lambda MM, who underwent an autologous stem cell transplant in 2013, experienced a first relapse in October 2016 and was treated with lenalidomide 25 mg/day and dexamethasone weekly with a very good partial response. After 17 months of treatment, the patient presented with hypothermia, dyspnea, dizziness, diarrhoea and bone pain. He had 77 g/l haemoglobin with 9 × 109/l platelets and the presence of schistocytes on blood smear; LDH levels were high (655 U/l), with a low haptoglobin and creatinine level of 11 mg/l. Shigatoxin research in stools was negative, ADAMTS13 activity was undetectable at <5% with positive anti-ADAMTS13 IgG (>100 U/ml). The brain MRI was normal. The patient underwent 10 TPE with methylprednisolone of 1 mg/kg and one injection of rituximab with rapid clinical and biological improvement. Six months later, ADAMTS13 activity was 49% and platelet count was normal (246 × 109/l). The patient is currently being treated with bortezomib, cyclophosphamide and dexamethasone in partial response. These three cases of TTP occurred during lenalidomide therapy (Table 1)‒ there was nothing that can usually be associated with thrombotic microangiopathy ‒ no infectious trigger, no association with other autoimmune disorders, and no drugs intake. The PLASMIC score (Upadhyay et al., 2019) has stratified our three cases in the intermediate and high risk group for severe ADAMTS13 deficiency. To the best of our knowledge, only two other cases of TTP and treatment with lenalidomide in MM have been reported in literature (Hofmeister et al., 2010; Cheah et al., 2015). All five cases had a creatinine level under 23 mg/l (200 µmol/l) and platelet count under 30 × 109/l, which are predicting features of severe acquired ADAMTS13 deficiency on diagnosis (Coppo et al., 2010). Two mechanisms for drug-induced TTP have been proposed: immune-mediated reaction and dose-related toxicity (Al-Nouri et al., 2015). For our patients, the presence of anti-ADAMTS13 antibodies in each case and the efficacy of TPE and/or rituximab therapies imply an immune-mediated reaction. Montefusco et al. (2014) described six autoimmune diseases after lenalidomide administration to 140 patients (4·3%): three autoimmune cytopenias and three organ-specific autoimmune disorders, occurring mostly in the first months of treatment. In the first case, ADAMTS13 activity (which was tested on frozen serum samples), was normal five years prior to lenalidomide initiation and decreased to <5% one month after its initiation. This strongly suggests the emergence of anti-ADAMTS13 antibodies after lenalidomide initiation. After lenalidomide discontinuation, the patients were not rechallenged with the drug. Dose-related toxicity cannot be ruled out. Lu et al. (2009) showed in vitro that lenalidomide inhibits VEGF-induced endothelial cell cord formation in a dose-dependent manner, and it was also demonstrated in hepatocellular carcinoma cells that lenalidomide inhibits angiogenesis via a VEGF pathway (Qu et al., 2016). Local reduction of VEGF within the kidney has been proved sufficient to trigger microvascular injury, particularly to glomerular capillaries and renal podocytes, leading to TMA (Eremina et al., 2008). This supports the concept that local production of VEGF plays a critical protective role in the pathogenesis of microangiopathic processes. Also, in the first months of treatment, immunomodulators induce a transitory rise of factors VIII and vWF, an acquired resistance to the activated protein C, and a reduction of the soluble thrombomodulin rate: favourable conditions for thrombosis (Boyle et al., 2012). The physiopathology needs to be clarified but one can make several hypotheses: lenalidomide could induce development of anti-ADAMTS13 antibodies leading to TTP; it could also facilitate endothelial lesions (via a VEGF inhibition), leading to TMA and promoting a pro-thrombotic environment. Although rare, if bicytopenia occurs with high LDH levels when treating patients with lenalidomide, this could imply TTP and we suggest considering its early discontinuation. DE, AT, NL, SH, LG, AA, SR, EA, BR, BA have taken care of patients, collected clinical and laboratory information and gave therapeutic advice. DE, AT, BR and BA wrote the letter. DE, AT, NL, SH, LG, AA, SR, EA, PC BR, BA carefully read and critically reviewed the letter. AV and BJ performed the ADAMTS13 analysis. None of the authors has a relevant conflict of interest.