Maturation and persistence of the anti-SARS-CoV-2 memory B cell response.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

SARS-CoV-2 Omicron BA.1 breakthrough infection drives late remodeling of the memory B cell repertoire in vaccinated individuals.

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after SARS-CoV-2 Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of the COVID-19 mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reactions, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with a marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies.

Human anti-smallpox long-lived memory B cells are defined by dynamic interactions in the splenic niche and long-lasting germinal center imprinting.

Memory B cells (MBCs) can persist for a lifetime, but the mechanisms that allow their long-term survival remain poorly understood. Here, we isolated and analyzed human splenic smallpox/vaccinia protein B5-specific MBCs in individuals who were vaccinated more than 40 years ago. Only a handful of clones persisted over such an extended period, and they displayed limited intra-clonal diversity with signs of extensive affinity-based selection. These long-lived MBCs appeared enriched in a CD21hiCD20hi IgG+ splenic B cell subset displaying a marginal-zone-like NOTCH/MYC-driven signature, but they did not harbor a unique longevity-associated transcriptional or metabolic profile. Finally, the telomeres of B5-specific, long-lived MBCs were longer than those in patient-paired naive B cells in all the samples analyzed. Overall, these results imply that separate mechanisms such as early telomere elongation, affinity selection during the contraction phase, and access to a specific niche contribute to ensuring the functional longevity of MBCs.

Analysis of mRNA vaccination-elicited RBD-specific memory B cells reveals strong but incomplete immune escape of the SARS-CoV-2 Omicron variant.

The SARS-CoV-2 Omicron variant can escape neutralization by vaccine-elicited and convalescent antibodies. Memory B cells (MBCs) represent another layer of protection against SARS-CoV-2, as they persist after infection and vaccination and improve their affinity. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant remains unclear. We assessed the affinity and neutralization potency against the Omicron variant of several hundred naturally expressed MBC-derived monoclonal IgG antibodies from vaccinated COVID-19-recovered and -naive individuals. Compared with other variants of concern, Omicron evaded recognition by a larger proportion of MBC-derived antibodies, with only 30% retaining high affinity against the Omicron RBD, and the reduction in neutralization potency was even more pronounced. Nonetheless, neutralizing MBC clones could be found in all the analyzed individuals. Therefore, despite the strong immune escape potential of the Omicron variant, these results suggest that the MBC repertoire generated by mRNA vaccines still provides some protection against the Omicron variant in vaccinated individuals.

mRNA vaccination of naive and COVID-19-recovered individuals elicits potent memory B cells that recognize SARS-CoV-2 variants.

In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs.

Immune thrombocytopenia and pregnancy: an exposed/nonexposed cohort study.

The risk of immune thrombocytopenia (ITP) worsening during pregnancy and neonatal ITP (NITP) have never been prospectively studied. We included 180 pregnant and 168 nonpregnant women with ITP in a prospective, multicenter, observational cohort study. A total of 131 pregnant women with ITP were matched to 131 nonpregnant women with ITP by history of splenectomy, ITP status (no response, response, complete response), and duration. Groups were followed for 15 months. The primary outcome was the first occurrence of ITP worsening defined by a composite end point including bleeding events and/or severe thrombocytopenia (<30 × 109/L) and/or ITP treatment modification. We also studied the recurrence of ITP worsening and the incidence of NITP and risk factors. The first occurrence of ITP worsening did not differ between pregnant and nonpregnant women with ITP (53.4 per 100 person-years [95% confidence interval {CI}, 40.8-69.9] vs 37.1 [95% CI, 27.5-50.0]; hazard ratio {HR}, 1.35 [95% CI, 0.89-2.03], P = .16). Pregnant women with ITP were more likely to have recurrence of severe thrombocytopenia and treatment modification (HR, 2.71 [95% CI, 1.41-5.23], P = .003; HR, 2.01 [95% CI, 1.14-3.57], P = .017, respectively). However, recurrence of severe bleeding events was not different between groups (P = .4). Nineteen (14%) neonates showed NITP <50 × 109/L. By multivariable analysis, NITP was associated with a previous offspring with NITP and maternal platelet count <50 × 109/L within 3 months before delivery (adjusted odds ratio, 5.55 [95% CI, 1.72-17.89], P = .004 and 4.07 [95% CI, 1.41-11.73], P = .009). To conclude, women with ITP do not increase their risk of severe bleeding during pregnancy. NITP is associated with NITP history and the severity of maternal ITP during pregnancy. These results will be useful for counseling women with ITP.

Prolonged response after TPO-RA discontinuation in primary ITP: results of a prospective multicenter study.

Sustained response off treatment (SROT) after thrombopoietin receptor agonist (TPO-RA) discontinuation has been reported in immune thrombocytopenia (ITP). This prospective multicenter interventional study enrolled adults with persistent or chronic primary ITP and complete response (CR) on TPO-RAs. The primary end point was the proportion of patients achieving SROT (platelet count >30 × 109/L and no bleeding) at week 24 (W24) with no other ITP-specific medications. Secondary end points included the proportion of sustained CR off-treatment (SCROT, platelet count >100 × 109/L and no bleeding) and SROT at W52, bleeding events, and pattern of response to a new course of TPO-RAs. We included 48 patients with a median age of 58.5 years; 30 of 48 had chronic ITP at TPO-RA initiation. In the intention-to-treat analysis, 27 of 48 achieved SROT, 15 of 48 achieved SCROT at W24; 25 of 48 achieved SROT, and 14 of 48 achieved SCROT at W52. No severe bleeding episode occurred in patients who relapsed. Among patients rechallenged with TPO-RA, 11 of 12 achieved CR. We found no significant clinical predictors of SROT at W24. Single-cell RNA sequencing revealed enrichment of a tumor necrosis factor α signaling via NF-κB signature in CD8+ T cells of patients with no sustained response after TPO-RA discontinuation, which was further confirmed by a significant overexpression of CD69 on CD8+ T cells at baseline in these patients as compared with those achieving SCROT/SROT. Our results strongly support a strategy based on progressive tapering and discontinuation of TPO-RAs for patients with chronic ITP who achieved a stable CR on treatment. This trial was registered at www.clinicaltrials.gov as #NCT03119974.

B-cell responses to ITP treatments.

Deficiency in regulatory B cells has been suggested in immune thrombocytopenia. In this study, Stimpson et al. emphasize the importance of considering the treatments received for immunological analyses. Commentary on: Stimpson et al. Systemic immunosuppression depletes peripheral blood regulatory B cells in patients with immune thrombocytopenia. Br J Haematol 2024;204:644-648.

Difficult-to-treat primary immune thrombocytopenia in adults: Prevalence and burden. Results from the CARMEN-France registry.

The aim of this study was to assess the prevalence and the burden of difficult-to-treat primary ITP (pITP), defined by the need for another ITP treatment after romiplostim and eltrombopag. Adult patients were selected in the prospective, real-world CARMEN-France registry up to December 2021. Out of 821 adult patients with pITP, 29 had difficult-to-treat ITP (3.5%; 95% confidence interval [CI]: 2.3%-4.8% in total; 7.6%; 95% CI: 4.9%-10.2% of patients needing ≥2nd line treatment). The 3-year cumulative incidence of bleeding, infection and thrombosis was 100%, 24.1% and 13.8% respectively. The median cumulative duration of hospital stays was 31 days (median follow-up: 30.3 months).

B cells and antibodies in refractory immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an acquired bleeding disorder mediated by pathogenic autoantibodies secreted by plasma cells (PCs) in many patients. In refractory ITP patients, the persistence of splenic and bone marrow autoreactive long-lived PCs (LLPCs) may explain primary failure of rituximab and splenectomy respectively. The reactivation of autoreactive memory B cells generating new autoreactive PCs contributes to relapses after initial response to rituximab. Emerging strategies targeting B cells and PCs aim to prevent the settlement of splenic LLPCs with the combination of anti-BAFF and rituximab, to deplete autoreactive PCs with anti-CD38 antibodies, and to induce deeper B-cell depletion in tissues with novel anti-CD20 monoclonal antibodies and anti-CD19 therapies. Alternative strategies, focused on controlling autoantibody mediated effects, have also been developed, including SYK and BTK inhibitors, complement inhibitors, FcRn blockers and inhibitors of platelet desialylation.

Combining thrombopoietin receptor agonists with immunosuppressive drugs in adult patients with multirefractory immune thrombocytopenia, an update on the French experience.

Combining drugs could be an effective option for treating multirefractory ITP, that is, patients not responding to rituximab, thrombopoietin receptor agonists (TPO-RA) and splenectomy. We conducted a retrospective, multicenter, observational study including multirefractory ITP patients who received a combination of a TPO-RA and an immunosuppressive drug. We included 39 patients (67% women, median age 59 years [range 21-96]), with a median ITP duration of 57 months [3-393] and a median platelet count at initiation of 10 × 109 /L [1-35]. The combination regimen was given for a median duration of 12 months [1-103] and included eltrombopag (51%) or romiplostim (49%), associated with mycophenolate mofetil (54%), azathioprine (36%), cyclophosphamide (5%), cyclosporin (3%) or everolimus (3%). Overall, 30 patients (77%) achieved at least a response (platelet count ≥30 × 109 /L and at least doubling baseline during at least 3 months), including 24 complete responses (platelet count >100 × 109 /L during at least 3 months) with a median time to response of 30 days [7-270] and a median duration of response of 15 months [4-63]. Severe adverse event related to ITP treatment was observed in 31%. In conclusion, this study confirms that some patients with multirefractory ITP can achieve long lasting response with this combination.

Hematologic disorder-associated Cxcr4 gain-of-function mutation leads to uncontrolled extrafollicular immune response.

The extrafollicular immune response is essential to generate a rapid but transient wave of protective antibodies during infection. Despite its importance, the molecular mechanisms controlling this first response are poorly understood. Here, we demonstrate that enhanced Cxcr4 signaling caused by defective receptor desensitization leads to exacerbated extrafollicular B-cell response. Using a mouse model bearing a gain-of-function mutation of Cxcr4 described in 2 human hematologic disorders, warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome and Waldenström macroglobulinemia, we demonstrated that mutant B cells exhibited enhanced mechanistic target of rapamycin signaling, cycled more, and differentiated more potently into plasma cells than wild-type B cells after Toll-like receptor (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 after T-independent 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 and safety of methylprednisolone pulse followed by oral prednisone vs. oral prednisone alone in sarcoidosis tubulointerstitial nephritis: a randomized, open-label, controlled clinical trial.

BACKGROUND: We determine the benefit of pulsed methylprednisolone for improving kidney function in patients with sarcoidosis tubulointerstitial nephritis. METHODS: We conducted a multicenter, prospective, randomized, open-label, controlled trial in patients with biopsy-proven acute tubulointerstitial nephritis caused by sarcoidosis at 21 sites in France. Patients were randomly assigned to receive a methylprednisolone pulse 15 mg/kg/day for 3 days, then oral prednisone (MP group) or oral prednisone 1 mg/kg/day alone (PRD group). The primary end point was a positive response at 3 months, defined as a doubling of estimated glomerular filtration rate (eGFR) compared with the eGFR before randomization. RESULTS: We randomized 40 participants. Baseline eGFR before PRD was 22 mL/min/1.73m2 {interquartile range [IQR], 16-44} and before MP was 25 mL/min/1.73m2 (IQR, 22-36) (P = .3). The two groups did not differ in underlying pathological lesions, including mean percentage of interstitial fibrosis and intensity of interstitial infiltrate. In the intent-to-treat population, the median eGFR at 3 months did not significantly differ between the PRD and MP groups: 45 (IQR, 34-74) and 46 (IQR, 39-65) mL/min/1.73m2. The primary end point at 3 months was achieved in 16 of 20 (80%) PRD patients and 10 of 20 (50%) MP patients (P = .0467). The eGFR was similar between the two groups after 1, 3, 6, and 12 months of treatment. For both groups, eGFR at 1 month was strongly correlated with eGFR at 12 months (P < .0001). The two groups did not differ in severe adverse events. CONCLUSION: Compared with a standard oral steroid regimen, intravenous MP may have no supplemental benefit for renal function in patients with tubulointerstitial nephritis caused by sarcoidosis.Trial Registration: ClinicalTrials.gov: NCT01652417; EudraCT: 2012-000149-11.

Efficacy and safety of two rituximab biosimilars for treating immune thrombocytopenia: a reference-product matched study.

The emergence of rituximab biosimilars offers the prospect of significant savings to the healthcare system. However, these drugs have never been evaluated for treating immune thrombocytopenia (ITP). This was an observational, matched study. We included adults who received a rituximab biosimilar for ITP. Each rituximab-naïve biosimilar patient was matched with two controls from the historic ITP-ritux registry. For non-naïve patients, we compared the response to the biosimilar with that observed with the reference product. Response status was defined according to international criteria. We included 107 patients; 55 receiving Rixathon™ and 52 Truxima™. Three months after the first infusion of rituximab biosimilars, the overall response rate was 47/74 (63.5%) versus 76/142 (53.5%) for the matched controls receiving the reference product (p = .13). The 3-month overall response rate was 76.5% for Rixathon™ versus 51.5% for the matched control group (p = .01) and 21/40 (52.5%) for Truxima™ versus 41/74 (55.4%) for the matched controls (p = .81). For non-naïve patients, the response pattern was similar to that observed previously with the reference product. Safety was analogous to that observed with the reference product. Rituximab biosimilars seemed safe and effective for ITP treatment.

What is the context? Immune thrombocytopenia (ITP) is an autoimmune disease defined by a low platelet count without any other cause of thrombocytopenia. Patients with ITP may experience severe bleedings.Rituximab, a biotechnological therapy, is a valid second-line treatment option for ITP.Biotechnological therapies are expensive. Because the patent expiratory date of the reference product of Rituximab expired, highly similar drugs called biosimilars have been developed and used in ITP treatment without any direct evaluation in this particular disease.What is new? In this study, we evaluate the efficacy and safety of rituximab biosimilars versus the reference product for treating adult ITPWe included adults who received a rituximab biosimilar for ITP. Each rituximab-naïve biosimilar patient was matched with two controls from a historic registry that included ITP patients treated by the reference product. For non-naïve patients, we compared the response to the biosimilar with that observed with the reference product.For naïve and non-naïve patients, the response pattern was similar to that observed previously with the reference product. Safety was analogous to that observed with the reference product.What is the impact? This study provides further evidence that rituximab biosimilars are safe and effective for immune thrombocytopenia treatment.

Primary immune thrombocytopenia in very elderly patients: particularities in presentation and management: results from the prospective CARMEN-France Registry.

Data about the presentation and the management of primary immune thrombocytopenia (ITP) in very elderly patients (VEPs; aged ≥80 years) are lacking. The aim of the present study was to describe ITP in this subgroup. The data source was the prospective CARMEN-France registry. Patients included between 2013 and 2018 were selected. ITP presentation and management in VEPs was compared to elderly patients (EPs; aged 65-79 years). We assessed factors associated with bleeding at ITP onset in VEPs. Of 541 patients, 184 were included: 87 in the VEP group and 97 in the EP group. The mean age was 85·7 years in the VEP group. Comorbidities were more frequent in the VEP group (67·4% vs. 47·9%). The median platelet count at ITP onset was similar but severe bleeding tended to be more frequent in VEPs (10·3% vs. 4·1%, P = 0·1) as well as mortality. Exposure to ITP drugs, response to first-line treatment, need of second-line treatment, evolution towards persistency, occurrence of bleeding, infection and thrombosis did not differ between groups. In VEPs, factors associated to bleeding were female sex [odds ratio (OR) 4·75, 95% confidence interval (CI) 1·31-17·32] and platelet count of <20 × 109 /l (OR 10·05, 95% CI 4·83-67·39). Exposure to anticoagulants was strongly associated with severe bleeding (OR 7·61, 95% CI 1·77-32·83).

Efficacy of plasma exchange in patients with anti-MDA5 rapidly progressive interstitial lung disease.

BACKGROUND: Rapidly progressive interstitial lung disease (RP-ILD) is a frequent and severe manifestation of anti-MDA5 dermatomyositis (MDA5-DM) associated with poor outcome. The optimal treatment regimen for MDA5-DM RP-ILD is yet to be determined. Specifically, the value of adding plasma exchange (PLEX) to corticosteroids and immunosuppressants remains unclear. We aimed to evaluate the effect of PLEX on the outcome of patients with MDA5-DM RP-ILD. METHODS: This French nationwide multicentre retrospective study included all MDA5-DM RP-ILD patients from 2012 to 2021 admitted to 18 centres. The primary endpoint was one-year transplant-free survival. RESULTS: 51 patients with MDA5-DM RP-ILD (female 67%; mean age at disease onset: 51 ± 11.6 years) were included. Thirty-two (63%) patients required mechanical ventilation and twenty-five (49%) received PLEX. One-year mortality or lung transplant occurred in 63% cases after a median follow-up of 77 [38-264] days. The Cox proportional hazards multivariable model only retained mechanical ventilation but not PLEX (p = 0.7) as independent predictor of the primary endpoint. One-year transplant-free survival rates in PLEX + vs. PLEX-were 20% vs. 54% (p = 0.01), respectively. The Kaplan-Meier estimated probabilities of one-year transplant-free survival was statistically higher in PLEX-compared to PLEX + patients (p = 0.05). PLEX + compared to PLEX-patients more frequently received mechanical ventilation and immunosuppressants suggesting PLEX + patients had a more severe disease. CONCLUSION: MDA5-DM RP-ILD is associated with poor rate of one-year transplant-free survival. The use of PLEX was not associated with a better outcome albeit they were mainly given to more severe patients. While our study reports the largest series of MDA5-DM RP-ILD given PLEX, these results needs to be interpreted with caution owing the numerous selection, indication and interpretation bias. Further studies are needed to evaluate their efficacy in this setting.

Convalescent plasma therapy for B-cell-depleted patients with protracted COVID-19.

Anti-CD20 monoclonal antibodies are widely used for the treatment of hematological malignancies or autoimmune disease but may be responsible for a secondary humoral deficiency. In the context of COVID-19 infection, this may prevent the elicitation of a specific SARS-CoV-2 antibody response. We report a series of 17 consecutive patients with profound B-cell lymphopenia and prolonged COVID-19 symptoms, negative immunoglobulin G (IgG)-IgM SARS-CoV-2 serology, and positive RNAemia measured by digital polymerase chain reaction who were treated with 4 units of COVID-19 convalescent plasma. Within 48 hours of transfusion, all but 1 patient experienced an improvement of clinical symptoms. The inflammatory syndrome abated within a week. Only 1 patient who needed mechanical ventilation for severe COVID-19 disease died of bacterial pneumonia. SARS-CoV-2 RNAemia decreased to below the sensitivity threshold in all 9 evaluated patients. In 3 patients, virus-specific T-cell responses were analyzed using T-cell enzyme-linked immunospot assay before convalescent plasma transfusion. All showed a maintained SARS-CoV-2 T-cell response and poor cross-response to other coronaviruses. No adverse event was reported. Convalescent plasma with anti-SARS-CoV-2 antibodies appears to be a very promising approach in the context of protracted COVID-19 symptoms in patients unable to mount a specific humoral response to SARS-CoV-2.

Clinical phenotypes of extrapulmonary sarcoidosis: an analysis of a French, multi-ethnic, multicentre cohort.

Sarcoidosis is a rare disease of unknown cause with wide heterogeneity in clinical features and outcomes. We aimed to explore sarcoidosis phenotypes and their clinical relevance with particular attention to extrapulmonary subgroups.The Epidemiology of Sarcoidosis (EpiSarc) study is a French retrospective multicentre study. Sarcoidosis patients were identified through national hospitalisation records using appropriate codes from 11 hospital centres between 2013 and 2016 according to a standardised protocol. Medical charts were reviewed. The phenotypes of sarcoidosis were defined using a hierarchical cluster analysis.A total of 1237 patients were included (562 men and 675 women). The mean age at sarcoidosis diagnosis was 43.5±13 years. Hierarchical cluster analysis identified five distinct phenotypes according to organ involvement and disease type and symptoms: 1) erythema nodosum, joint involvement and hilar lymph nodes (n=180); 2) eye, neurological, digestive and kidney involvement (n=137); 3) pulmonary involvement with fibrosis and heart involvement (n=630); 4) lupus pernio and a high percentage of severe involvement (n=41); and 5) hepatosplenic, peripheral lymph node and bone involvement (n=249). Phenotype 1 was associated with being European/Caucasian and female and with non-manual work, phenotype 2 with being European/Caucasian, and phenotypes 3 and 5 with being non-European/Caucasian. The labour worker proportion was significantly lower in phenotype 5 than in the other phenotypes.This multicentre study confirms the existence of distinct phenotypes of sarcoidosis, with a non-random distribution of organ involvement. These phenotypes differ according to sex, geographical origin and socioprofessional category.

Pure red cell aplasia in systemic lupus erythematosus, a nationwide retrospective cohort and review of the literature.

OBJECTIVES: To characterize the clinical and biological course, management and response to treatment in SLE-associated pure red cell aplasia (PRCA). METHODS: This was a nationwide, multicentre, retrospective cohort study. From 2006 to 2018, we included adults with a diagnosis of PRCA supported by bone marrow examination and SLE or biologic manifestations of SLE after ruling out parvovirus B19 infection. RESULTS: We enrolled 24 patients (20 women). SLE was diagnosed before PRCA for 14 patients (median delay 81 months). At PRCA diagnosis, mean age, haemoglobin level, and reticulocyte and differential erythroblast count were 39.2 (13.2) years, 62 ( 20) g/l, 9.1 (7.6) × 109/l and 2.8 ( 2.5)%, respectively. Eleven (45%) patients experienced multiple PRCA flares (median 6, range 2-11). CS therapy resulted in only three complete sustained responses, and 19 (79%) patients required immunosuppressive agents with highly variable regimens. After a median follow-up of 76 months (range 13-173), 17 (71%) patients showed complete response for PRCA, 5 (21%) partial response and 2 (8%) treatment failure. In total, 21 (87%) patients required red blood cell transfusion; 5 had a diagnosis of transfusion-related iron overload. Eighteen (75%) patients experienced severe infectious events requiring hospitalization. CONCLUSION: SLE-associated PRCA is a severe condition. Repeated red blood cell transfusions and several lines of immunosuppressant therapy are mostly required, with high risk of severe infectious events and iron overload. Despite sustained response for PRCA and SLE obtained in most patients, the best therapeutic strategy remains to be determined.

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.

B-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.