Daratumumab monotherapy in refractory warm autoimmune hemolytic anemia and cold agglutinin disease

Autoimmune hemolytic anemia (AIHA) is a rare autoantibody-mediated disease. For steroid and/or rituximab-refractory AIHA, there is no consensus on optimal treatment. Daratumumab, a monoclonal antibody targeting CD38, could be beneficial by suppression of CD38+ plasma cells and thus autoantibody secretion. In addition, because CD38 is also expressed by activated T cells, daratumumab may also act via immunomodulatory effects. We evaluated the efficacy and safety of daratumumab monotherapy in an international retrospective study including 19 adult patients with heavily pretreated refractory AIHA. In warm AIHA (wAIHA, n = 12), overall response was 50% with a median response duration of 5.5 months (range, 2-12), including ongoing response in 2 patients after 6 and 12 months. Of 6 nonresponders, 4 had Evans syndrome. In cold AIHA (cAIHA, n = 7) overall hemoglobin (Hb) response was 57%, with ongoing response in 3 of 7 patients. One additional patient with nonanemic cAIHA was treated for severe acrocyanosis and reached a clinical acrocyanosis response as well as a Hb increase. Of 6 patients with cAIHA with acrocyanosis, 4 had improved symptoms after daratumumab treatment. In 2 patients with wAIHA treated with daratumumab, in whom we prospectively collected blood samples, we found complete CD38+ T-cell depletion after daratumumab, as well as altered T-cell subset differentiation and a severely diminished capacity for cell activation and proliferation. Reappearance of CD38+ T cells coincided with disease relapse in 1 patient. In conclusion, our data show that daratumumab therapy may be a treatment option for refractory AIHA. The observed immunomodulatory effects that may contribute to the clinical response deserve further exploration.</p

Br J Haematol

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Efficacy and Safety of a Combination of Thrombopoietin Receptor Agonist with an Immunosuppressant Therapy for the Management of Multirefractory Adult ITP: Results from a Retrospective, Multicenter, Observational Study

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Clinical Spectrum, Quality of Life, BRAF Mutation Status and Treatment of Skin Involvement in Adult Langerhans Cell Histiocytosis

Langerhans cell histiocytosis is a rare histiocytic disorder for which skin involvement and management are poorly described in adults. The aim of this retrospective monocentric study in a national reference centre is to describe the clinical characteristics, quality of life, BRAF mutation status and outcomes of skin involvement in adult patients with Langerhans cell histiocytosis. Twenty-five patients (14 females, mean age 47 years) were included, with a median follow-up of 33 months (range 4–420 months). Patients experienced poor dermatological quality of life despite low body surface involvement. BRAFV600 mutations were detected in 8 of the 18 patients analysed (45%). Eight patients had an associated malignancy. Several treatment options were used and consisted of surgery, topical steroids and carmustine, thalidomide, methotrexate, vinblastine and steroids and cladribine. This study highlights the need to evaluate quality of life and to screen for associated malignancy in adult patients with Langerhans cell histiocytosis

Bortezomib and dexamethasone, an original approach for treating multi‐refractory warm autoimmune haemolytic anaemia

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Rituximab-resistant splenic memory B cells and newly engaged naive B cells fuel relapses in patients with immune thrombocytopenia

International audienceRituximab (RTX), an antibody targeting CD20, is widely used as a first-line therapeutic strategy in B cell–mediated autoimmune diseases. However, a large proportion of patients either do not respond to the treatment or relapse during B cell reconstitution. Here, we characterize the cellular basis responsible for disease relapse in secondary lymphoid organs in humans, taking advantage of the opportunity offered by therapeutic splenectomy in patients with relapsing immune thrombocytopenia. By analyzing the B and plasma cell immunoglobulin gene repertoire at bulk and antigen-specific single-cell level, we demonstrate that relapses are associated with two responses coexisting in germinal centers and involving preexisting mutated memory B cells that survived RTX treatment and naive B cells generated upon reconstitution of the B cell compartment. To identify distinctive characteristics of the memory B cells that escaped RTX-mediated depletion, we analyzed RTX refractory patients who did not respond to treatment at the time of B cell depletion. We identified, by single-cell RNA sequencing (scRNA-seq) analysis, a population of quiescent splenic memory B cells that present a unique, yet reversible, RTX-shaped phenotype characterized by down-modulation of B cell–specific factors and expression of prosurvival genes. Our results clearly demonstrate that these RTX-resistant autoreactive memory B cells reactivate as RTX is cleared and give rise to plasma cells and further germinal center reactions. Their continued surface expression of CD19 makes them efficient targets for current anti-CD19 therapies. This study thus identifies a pathogenic contributor to autoimmune diseases that can be targeted by available therapeutic agents

Hematological disorder associated Cxcr4-gain-of-function mutation leads to uncontrolled extrafollicular immune response Short title: Cxcr4 signaling and the extrafollicular response

International audienceThe extrafollicular immune response is essential to generate a rapid but transient wave of protective antibodies upon infection. Despite its importance, the molecular mechanisms controlling this first response are poorly understood. Here, we demonstrate that enhanced Cxcr4 signaling due to defective receptor desensitization leads to exacerbated extrafollicular B cell response. Using a mouse model bearing a gain of function mutation of Cxcr4 described in two human hematological disorders, WHIM syndrome and Waldenström's Macroglobulinemia, we demonstrated that mutant B cells exhibited enhanced mTOR signaling, cycled more and differentiated more potently into plasma cells than wild-type B cells upon TLR stimulation. Moreover, Cxcr4 gain-of-function promoted enhanced homing and persistence of immature plasma cells in the bone marrow, a phenomenon recapitulated in WHIM syndrome patient samples. This translated in increased and more sustained production of antibodies upon Tindependent immunization in Cxcr4 mutant mice. Thus, our results establish that fine-tuning of Cxcr4 signaling is essential to limit the strength and length of the extrafollicular immune response

Efficacy, safety and immunological profile of combining rituximab with belimumab for adults with persistent or chronic immune thrombocytopenia: results from a prospective phase 2b trial

International audienceB-cell activating factor may be involved in the failure of B-cell depleting therapy with rituximab in immune thrombocytopenia (ITP) by promoting the emergence of splenic long-lived plasma cells. From results obtained in mouse models, we hypothesized that combining rituximab with sequential injections of belimumab could increase the rate of response at one year in patients with persistent or chronic ITP by preventing the emergence of these long-lived plasma cells. The study was a single-center, single arm, prospective phase 2b trial (RITUX-PLUS, NCT03154385) investigating the safety and efficacy of rituximab given at a fixed dose of 1,000 mg, two weeks apart, combined with five infusions of belimumab, 10 mg/kg at week 0 (W0)+2 days, W2+2 days, W4, W8 and W12 for adults with primary persistent or chronic ITP. The primary endpoint was the total number of patients achieving an overall response (complete response + response) at W52 according to a standard definition. In total, 15 non-splenectomized adults, nine (60%) with persistent IPT and six (40%) with chronic ITP, were included. No severe adverse event, infection, or severe hypogammaglobulinemia was observed. Thirteen patients achieved an initial overall response. At W52, 12 (80%) patients achieved an overall response, including ten (66.7%) with complete response. When compared with a cohort of patients receiving rituximab alone, the kinetics of B-cell repopulation appeared similar, but the number of circulating T follicular helper cells was significantly decreased with belimumab combination therapy. Combining rituximab and belimumab seems a promising strategy in ITP, with high efficacy and acceptable safety