Cancer and multiple sclerosis: 2023 recommendations from the French Multiple Sclerosis Society.

BACKGROUND: Epidemiological data reveal that 45% of persons with multiple sclerosis (PwMS) in France are more than 50 years. This population more than 50 is more susceptible to cancer, and this risk may be increased by frequent use of immunosuppressive drugs. Consequently, concerns have arisen about the potential increased risk of cancer in PwMS and how patients should be screened and managed in terms of cancer risk. OBJECTIVE: To develop evidence-based recommendations to manage the coexistence of cancer and multiple sclerosis (MS). METHODS: The French Group for Recommendations in MS collected articles from PubMed and university databases covering the period January 1975 through June 2022. The RAND/UCLA method was employed to achieve formal consensus. MS experts comprehensively reviewed the full-text articles and developed the initial recommendations. A group of multidisciplinary health care specialists then validated the final proposal. RESULTS: Five key questions were addressed, encompassing various topics such as cancer screening before or after initiating a disease-modifying therapy (DMT), appropriate management of MS in the context of cancer, recommended follow-up for cancer in patients receiving a DMT, and the potential reintroduction of a DMT after initial cancer treatment. A strong consensus was reached for all 31 recommendations. CONCLUSION: These recommendations propose a strategic approach to managing cancer risk in PwMS.

Clinical and Prognostic Factors in Patients with IgG4-Related Kidney Disease.

BACKGROUND: IgG4-related kidney disease is a major manifestation of IgG4-related disease, a systemic fibroinflammatory disorder. However, the clinical and prognostic kidney-related factors in patients with IgG4-related kidney disease are insufficiently defined. METHODS: We conducted an observational cohort study using data from 35 sites in two European countries. Clinical, biologic, imaging, and histopathologic data; treatment modalities; and outcomes were collected from medical records. Logistic regression was performed to identify the possible factors related to an eGFR ≤30 ml/min per 1.73 m 2 at the last follow-up. Cox proportional hazards model was performed to assess the factors associated with the risk of relapse. RESULTS: We studied 101 adult patients with IgG4-related disease with a median follow-up of 24 (11-58) months. Of these, 87 (86%) patients were male, and the median age was 68 (57-76) years. Eighty-three (82%) patients had IgG4-related kidney disease confirmed by kidney biopsy, with all biopsies showing tubulointerstitial involvement and 16 showing glomerular lesions. Ninety (89%) patients were treated with corticosteroids, and 18 (18%) patients received rituximab as first-line therapy. At the last follow-up, the eGFR was below 30 ml/min per 1.73 m 2 in 32% of patients; 34 (34%) patients experienced a relapse, while 12 (13%) patients had died. By Cox survival analysis, the number of organs involved (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.01 to 1.55) and low C3 and C4 concentrations (HR, 2.31; 95% CI, 1.10 to 4.85) were independently associated with a higher risk of relapse, whereas first-line therapy with rituximab was protective (HR, 0.22; 95% CI, 0.06 to 0.78). At their last follow-up, 19 (19%) patients had an eGFR ≤30 ml/min per 1.73 m 2 . Age (odd ratio [OR], 1.11; 95% CI, 1.03 to 1.20), peak serum creatinine (OR, 2.74; 95% CI, 1.71 to 5.47), and serum IgG4 level ≥5 g/L (OR, 4.46; 95% CI, 1.23 to 19.40) were independently predictive for severe CKD. CONCLUSIONS: IgG4-related kidney disease predominantly affected middle-aged men and manifested as tubulointerstitial nephritis with potential glomerular involvement. Complement consumption and the number of organs involved were associated with a higher relapse rate, whereas first-line therapy with rituximab was associated with lower relapse rate. Patients with high serum IgG4 concentrations (≥5 g/L) had more severe kidney disease.

Precipitating factors of catastrophic antiphospholipid syndrome: the role of anticoagulant treatment in a series of 112 patients.

BACKGROUND: The prevention of catastrophic antiphospholipid syndrome (CAPS), a rare complication of antiphospholipid syndrome (APS), is a major goal. OBJECTIVES: We analyzed its precipitating factors, focusing on anticoagulation immediately before CAPS episodes. METHODS: We retrospectively analyzed patients in the French multicenter APS/systemic lupus erythematosus database with at least 1 CAPS episode. Then we compared each patient with known APS before CAPS with 2 patients with non-CAPS APS matched for age, sex, center, and APS phenotype. RESULTS: We included 112 patients with CAPS (70% women; mean age, 43 ± 15 years). At least 1 standard precipitating factor of CAPS was observed for 67 patients (64%), which were mainly infections (n = 28, 27%), pregnancy (n = 23, 22%), and surgery (n = 16, 15%). Before the CAPS episode, 67 (60%) patients already had a diagnosis of APS. Of the 61 treated with anticoagulants, 32 (48%) received vitamin K antagonists (VKAs), 23 (34%) heparin, and 2 (3%) a direct oral anticoagulant. They were less likely than their matched patients with APS without CAPS to receive VKA (48% vs 66%, p = .001). Among those treated with VKA, 72% had a subtherapeutic international normalized ratio (ie, <2) versus 28% in patients with APS without CAPS (p < .001). Finally, excluding pregnant patients (n = 14) for whom we could not differentiate the effect of treatment from that of pregnancy, we were left with 47 cases, 32 (68%) of whom had recently begun a direct oral anticoagulant, planned bridging therapy, or had VKA treatment with international normalized ratio <2. CONCLUSION: These results strongly suggest that suboptimal anticoagulation management can trigger CAPS in patients with thrombotic APS.

Severe Libman-Sacks endocarditis complicating antiphospholipid syndrome: a retrospective analysis of 23 operated cases.

OBJECTIVE: Data on severe heart valve disease (HVD), including Libman-Sacks endocarditis, associated with SLE and/or APS requiring valvular surgery are scarce. We thus conducted a retrospective study, aimed at describing and clarifying clinical, laboratory, echocardiographic, histopathological and evolutional features of SLE and/or APS patients with severe associated-HVD. METHODS: An observational retrospective multicentric analysis of 23 adults with SLE and/or APS and HVD between 1996 and 2019 and available histopathological report evaluating long-term follow-up. RESULTS: Twenty-three individuals (20 females, median age 37 [range 17-76] years) were included. All had APS (thrombotic in 22, with an arterial phenotype in 15 and with catastrophic APS [CAPS] in six), and 11 (47%) had SLE. Systemic underlying disease had been diagnosed prior to HVD in 12 (52%). In 10 patients (43%), HVD was complicated by cerebral stroke prior to surgery. Twenty patients (87%) had only one pathological valve, the mitral valve in 18 patients (78%). Valvular thickening (n = 19) and valvular regurgitation (n = 19) were the most frequently reported lesions. Fifteen (62%) patients underwent mechanical valve replacement, six (26%) conservative valve repair (five were later re-operated after a median time of 1 [0-4] year), and two (9%) underwent biological valve replacement. Nine patients (39%) presented early-onset post-operative complications, including three CAPS immediately after surgery and one death. After surgery, 18 patients (78%) had normal postoperative valvular function, but almost half of the patients (43%) had post-operative neurological sequelae (median follow-up of 6 [2-20] years). CONCLUSION: Severe HVD leading to surgery was strongly associated with thrombotic APS, especially arterial phenotypes. Half of the reported patients presented cerebral stroke complicating the HVD. Valvular surgery carried a significant risk of CAPS.

Clonal haematopoiesis of indeterminate potential and cardiovascular events in systemic lupus erythematosus (HEMATOPLUS study).

OBJECTIVE: The detection of somatic mutations among the genes of myeloid cells in asymptomatic patients-defining clonal haematopoiesis of indeterminate potential (CHIP)-is associated with a predisposition to cardiovascular events (CVEs) in the general population. We aimed to determine whether CHIP was associated with CVEs in SLE patients. METHODS: The study is an ancillary study of the randomized, double-blind, placebo-controlled, multicentre PLUS trial conducted from June 2007 through August 2010 at 37 centres in France, involving 573 SLE patients. The search for somatic mutations by high-throughput sequencing of 53 genes involved in clonal haematopoiesis was performed on genomic DNA collected at PLUS inclusion. CHIP prevalence was assessed in SLE and in a retrospective cohort of 479 patients free of haematological malignancy. The primary outcome was an incident CVE in SLE. RESULTS: Screening for CHIP was performed in 438 SLE patients [38 (29-47) years, 91.8% female]. Overall, 63 somatic mutations were identified in 47 patients, defining a CHIP prevalence of 10.7% in SLE. Most SLE patients (78.7%) carried a single mutation. Most variants (62.5%) were located in the DNMT3A gene. CHIP frequency was related to age and to age at SLE diagnosis, and was associated with a lower frequency of aPLs. CHIP occurred >20 years earlier (P < 0.00001) in SLE than in controls. The detection of CHIP at inclusion was not found to be associated with occurrence of CVEs during follow-up [HR = 0.42 (0.06-3.21), P = 0.406]. CONCLUSION: The prevalence of CHIP is relatively high in SLE for a given age, but was not found to be associated with incident CVEs. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT05146414.

Characterisation of a high-risk profile for maternal thrombotic and severe haemorrhagic complications in pregnant women with antiphospholipid syndrome in France (GR2): a multicentre, prospective, observational study.

BACKGROUND: Prospective data about the risks of thrombotic and severe haemorrhagic complications during pregnancy and post partum are unavailable for women with antiphospholipid syndrome. We aimed to assess thrombotic and haemorrhagic events in a prospective cohort of pregnant women with antiphospholipid syndrome. METHODS: This multicentre, prospective, observational study was done at 76 centres in France. To be eligible for this study, women had to have diagnosis of antiphospholipid syndrome; have conceived before April 17, 2020; have an ongoing pregnancy that had reached 12 weeks of gestation; and be included in the study before 18 weeks of gestation. Exclusion criteria were active systemic lupus erythematosus nephropathy, or a multifetal pregnancy. Severe haemorrhage was defined as the need for red blood cell transfusion or maternal intensive care unit admission because of bleeding or invasive procedures, defined as interventional radiology or surgery, to control bleeding. The GR2 study is registered with ClinicalTrials.gov, NCT02450396. FINDINGS: Between May 26, 2014, and April 17, 2020, 168 pregnancies in 27 centres met the inclusion criteria for the study. 89 (53%) of 168 women had a history of thrombosis. The median term at inclusion was 8 weeks gestation. 16 (10%) of 168 women (95%CI 5-15) had a thrombotic (six [4%] women; 95% CI 1-8) or severe haemorrhagic event (12 [7%] women; 95% CI 4-12). There were no deaths during the study. The main risk factors for thrombotic events were lupus anticoagulant positivity at inclusion (six [100%] of six women with thrombosis vs 78 [51%] of 152 of those with no thrombosis; p=0·030) and placental insufficiency (four [67%] of six women vs 28 [17%] of 162 women; p=0·013). The main risk factors for severe haemorrhagic events were pre-existing maternal hypertension (four [33%] of 12 women vs 11 [7%] of 156 women; p=0·014), lupus anticoagulant positivity at inclusion (12 [100%] of 12 women vs 72 [49%] of 146 women; p<0·0001) and during antiphospholipid history (12 [100%] of 12 women vs 104 [67%] of 156 women; p=0·019), triple antiphospholipid antibody positivity (eight [67%] of 12 women vs 36 [24%] of 147 women; p=0·0040), placental insufficiency (five [42%] of 12 women vs 27 [17%] of 156 women; p=0·038), and preterm delivery at 34 weeks or earlier (five [45%] of 11 women vs 12 [8%] of 145 women; p=0·0030). INTERPRETATION: Despite treatment adhering to international recommendations, a proportion of women with antiphospholipid syndrome developed a thrombotic or severe haemorrhagic complication related to pregnancy, most frequently in the post-partum period. Lupus anticoagulant and placental insufficiency were risk factors for these life-threatening complications. These complications are difficult to prevent, but knowledge of the antenatal characteristics associated with them should increase awareness and help physicians manage these high-risk pregnancies. FUNDING: Lupus France, association des Sclérodermiques de France, association Gougerot Sjögren, Association Francophone contre la Polychondrite chronique atrophiante, AFM-Telethon, the French Society of Internal Medicine and Rheumatology, Cochin Hospital, the French Health Ministry, FOREUM, the Association Prix Veronique Roualet, and UCB.

Detection of Borrelia burgdorferi antigens in tissues and plasma during early infection in a mouse model.

Borrelia burgdorferi is the causative agent of Lyme borreliosis, which is the most common tick-borne human disease in Europe and North America. Currently, the diagnosis of Lyme borreliosis is based on serological tests allowing indirect detection of anti-Borrelia antibodies produced by patients. Their main drawback is a lack of sensitivity in the early phase of disease and an incapacity to prove an active infection. Direct diagnostic tests are clearly needed. The objectives of this study were to produce tools allowing sensitive detection of potential circulating Borrelia antigens and to evaluate them in a mouse model. We focused on two potential early bacterial makers, the highly variable OspC protein and the conserved protein FlaB. High-affinity monoclonal antibodies were produced and used to establish various immunoassays and western blot detection. A very good limit of detection for OspC as low as 17 pg/mL of sample was achieved with SPIE-IA. In infected mice, we were able to measure OspC in plasma with a mean value of 10 ng/mL at 7 days post-inoculation. This result suggests that OspC could be a good blood marker for diagnosis of Lyme borreliosis and that the tools developed during this study could be very useful.

Pulmonary hypertension associated with congenital heart block and neonatal lupus syndrome: A series of four cases.

OBJECTIVE: Neonatal lupus syndrome has multisystemic manifestations among which pulmonary involvement has been rarely reported. We describe the clinical presentation, management, and outcome of a series of four neonates who developed reversible pulmonary hypertension associated with auto-immune congenital complete heart block. METHOD: Data from the French registry of neonatal lupus syndrome were retrospectively reviewed. RESULTS: Between 2000 and March 2020, 231 children were included in the French registry, four/73 followed in our institution developed pulmonary hypertension. Diagnosis was suspected on transthoracic echocardiography at a median age of 42 days [range 10-58], and confirmed by right heart catheterization in all; 2 of them where paced at time of diagnosis and 2 were not. All had some degree of hypoxemia and respiratory distress. Hypoxemia was always reversible under O2 et NO. Lung CT demonstrated ground glass anomalies in all. One patient had a lung biopsy consistent with pulmonary hypertension secondary to lung disease. Management included immunosuppressive therapy in 3 associated with sildenafil in 2. Pulmonary hypertension resolved in all at a median age of 4 weeks [range 3-6] after treatment initiation and after one year for the one child who did not receive specific treatment. CONCLUSION: Clinical, hemodynamical, imaging and histological findings advocate for pulmonary hypertension associated with respiratory disease as a rare manifestation of neonatal lupus syndrome.

Top-Down and Bottom-Up Proteomics of Circulating S100A8/S100A9 in Plasma of Septic Shock Patients.

Well-characterized prognostic biomarkers and reliable quantitative methods are key in sepsis management. Among damage-associated molecular patterns, S100A8/S100A9 complexes are reported to be markers for injured cells and to improve the prediction of death in septic shock patients. In view of the structural diversity observed for the intracellular forms, insight into circulating complexes and proteoforms is required to establish prognostic biomarkers. Here, we developed top-down and bottom-up proteomics to characterize the association of S100A8 and S100A9 in complexes and major circulating proteoforms. An antibody-free method was developed for absolute quantification of S100A8/S100A9 in a cohort of 49 patients to evaluate the prognostic value on the first day after admission for septic shock. The predominant circulating forms identified by top-down proteomics were S100A8, mono-oxidized S100A8, truncated acetylated S100A9, and S-nitrosylated S100A9. S100A8, truncated acetylated S100A9, and mono-oxidized S100A8 discriminated between survivors and nonsurvivors, along with total S100A8/S100A9 measured by the antibody-free bottom-up method. Overall, new insights into circulating S100A8/S100A9 and confirmation of its prognostic value in septic shock are crucial in qualification of this biomarker. Also, the simple antibody-free assay would support the harmonization of S100A8/S100A9 measurements.

High plasma level of S100A8/S100A9 and S100A12 at admission indicates a higher risk of death in septic shock patients.

Biomarkers in sepsis for severity, prediction of outcome or reversibility of organ dysfunction are warranted. Measurements of plasma DAMP levels at admission can reflect the severity of cellular damage in septic shock, which might predict the prognosis and reduce the risk of overtreating patients with costly therapies. We measured plasma levels of two DAMPs, S100A8/S100A9 and S100A12 during the first 24 h of admission of septic shock patients. Forty-nine septic shock patients with a similar SOFA scores were selected from our sepsis database to compare a similar proportion of survivors and non-survivors. Plasma levels of S100A8/S100A9 and S100A12 were compared with healthy volunteers using in-house ELISA. Plasma levels of S100A8/S100A9 and S100A12 (5.71 [2.60-13.63] µg/mL and 0.48 [0.22-1.05] µg/mL) were higher in septic shock patients than in healthy volunteers (1.18 [0.74-1.93] µg/mL and 0.09 [0.02-0.39] µg/mL) (P < 0.0001 and P = 0.0030). Levels of S100A8/S100A9 and S100A12 in non-survivors at day 28 (11.70 [2.85-24.36] µg/mL and 0.62 [0.30-1.64] µg/mL) were significantly higher than in survivors (4.59 [2.16-7.47] µg/mL and 0.30 [0.20-0.49] µg/mL) (P = 0.0420 and P = 0.0248) and correlated well (Spearman r = 0.879, P < 0.0001). The high level of plasma calgranulins at admission in septic shock, were higher in non-survivors compared to survivors. These markers could indicate a higher risk of death when SOFA scores are similar and help the stratification of patients for improved care and therapy selection.

Classification of primary antiphospholipid syndrome as systemic lupus erythematosus: Analysis of a cohort of 214 patients.

OBJECTIVES: To assess the limitations of the SLICC (Systemic Lupus International Collaborating Clinics) classification criteria for systemic lupus erythematosus (SLE), in patients with primary antiphospholipid syndrome (PAPS). METHODS: Retrospective study of a cohort of APS patients (Sydney criteria). We successively excluded patients with (1) at least one "SLE-specific" manifestation (biopsy-proven SLE nephropathy, arthritis, cutaneous, or neurologic SLE manifestations, pericarditis, autoimmune haemolytic anaemia, oral and nasal ulcers, non-scarring alopecia, anti-dsDNA, and anti-Sm antibodies), (2) any other autoimmune connective tissue disease, and/or (3) antinuclear antibodies >1/320. Careful file review confirmed PAPS among the remaining patients. We then assessed the number of SLICC criteria each patient met. RESULTS: Among these 214 APS patients, we excluded 85 with at least one SLE-specific manifestation, 8 with another connective tissue disease, and 21 with antinuclear antibodies >1/320, leaving 100 patients with primary APS. Among them, 28% met at least 4 SLICC classification criteria including one clinical and one immunological criterion (antiphospholipid antibodies, aPL, by definition) and could thus theoretically be classified with SLE. Fourteen had an arterial phenotype (50%), 9 a history of catastrophic APS (32%), and 18 a triple-positive profile for aPL (64%). None had developed SLE during a median follow-up of 12 [6.5-17] years. CONCLUSION: Because 28% of our patients with longstanding and strictly defined PAPS could be mistakenly classified as SLE, they were at risk of deleterious therapeutic management. We therefore suggest that any future classification for SLE should specifically require at least one SLE-specific criterion for patients with aPL.

T Cell Polarization toward TH2/TFH2 and TH17/TFH17 in Patients with IgG4-Related Disease.

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disorder involving virtually every organ with a risk of organ dysfunction. Despite recent studies regarding B cell and T cell compartments, the disease's pathophysiology remains poorly understood. We examined and characterized subsets of circulating lymphocytes in untreated patients with active IgG4-RD. Twenty-eight consecutive patients with biopsy-proven IgG4-RD were included in a prospective, multicentric study. Lymphocytes' subsets were analyzed by flow cytometry, with analysis of TH1/TH2/TH17, TFH cells, and cytokine release by peripheral blood mononuclear cells. Results were compared to healthy controls and to patients with primary Sjögren's syndrome. Patients with IgG4-RD showed an increase of circulating T regulatory, TH2, TH17, and CD4+CXCR5+PD1+ TFH cell subsets. Accordingly, increased levels of IL-10 and IL-4 were measured in IgG-RD patients. TFH increase was characterized by the specific expansion of TFH2 (CCR6-CXCR3-), and to a lesser extent of TFH17 (CCR6+CXCR3-) cells. Interestingly, CD4+CXCR5+PD1+ TFH cells normalized under treatment. IgG4-RD is characterized by a shift of circulating T cells toward a TH2/TFH2 and TH17/TFH17 polarization. This immunological imbalance might be implicated in the disease's pathophysiology. Treatment regimens targeting such T cells warrant further evaluation.

[2016 review on catastrophic antiphospholipid syndrome]. / Syndrome catastrophique des antiphospholipides (CAPS) : revue 2016.

The catastrophic antiphospholipid syndrome (CAPS) develops in at least 1% of patients with antiphospholipid syndrome, either primary or associated with systemic lupus erythematosus. CAPS reveals the antiphospholipid syndrome in about 50% of cases. The CAPS is characterized by rapidly-progressive widespread thromboses mainly affecting the microvasculature in the presence of antiphospholipid antibodies. In a few days, the patients develop multiorgan failure with renal insufficiency with severe hypertension, pulmonary, cerebral, cardiac, digestive and/or cutaneous involvement. The vital prognosis is frequently engaged. CAPS is often precipitated by infectious diseases, surgical procedures and/or withdrawal or modification of the anticoagulation. CAPS overall mortality rate has decreased and is currently below 30%. The main differential diagnoses are other thrombotic microangiopathies, and heparin-induced thrombocytopenia. The treatment of CAPS consists of the association of anticoagulation and steroids, plus plasma exchange and/or intravenous immunoglobulins. Cyclophosphamide is added only in patients with active systemic lupus erythematosus. The potential contribution of some additional therapies (rituximab, eculizumab or sirolimus) needs to be assessed. The prevention of CAPS is essential and is based upon the adequate management of the perioperative period when surgery cannot be avoided, the prompt treatment and the prevention with immunization of infections and the education of patients with antiphospholipid syndrome, especially for the management of oral anticoagulants.

Systemic inflammatory and autoimmune manifestations associated with myelodysplastic syndromes and chronic myelomonocytic leukaemia: a French multicentre retrospective study.

OBJECTIVE: We describe myelodysplastic syndrome (MDS)-associated systemic inflammatory and autoimmune diseases (SIADs), their treatments and outcomes and the impact of SIADs on overall survival in a French multicentre retrospective study. METHODS: In this study, 123 patients with MDS and SIADs were analysed. RESULTS: Mean age was 70 years (s.d. 13) and the male:female ratio was 2. The SIADs were systemic vasculitis in 39 (32%) cases, CTD in 31 (25%) cases, inflammatory arthritis in 28 (23%) cases, a neutrophilic disorder in 12 (10%) cases and unclassified in 13 cases (11%). The SIADs fulfilled the usual classification criteria in 75 (66%) cases, while complete criteria were not reached in 21 (19%) cases. A significant association was shown between chronic myelomonocytic leukaemia (CMML) and systemic vasculitis (P = 0.0024). One hundred and eighteen (96%) SIAD patients were treated (91% with steroids), with an 83% response to first-line treatment, including 80% for steroids alone. A second-line treatment for SIADs was required for steroid dependence or relapse in 48% of cases. The effect of MDS treatment on SIADs could be assessed in 11 patients treated with azacytidine and SIAD response was achieved in 9/11 (80%) and 6/11 (55%) patients at 3 and 6 months, respectively. Compared with 665 MDS/CMML patients without SIADs, MDS/CMML patients with SIADs were younger (P < 0.01), male (P = 0.03), less often had refractory anaemia with ring sideroblasts (P < 0.01), more often had a poor karyotype (16% vs 11%, P = 0.04) and less frequently belonged to low and intermediate-1 International Prognostic Scoring System categories, but no survival difference was seen between patients with MDS-associated SIADs and without SIADs (P = 0.5). CONCLUSION: The spectrum of SIADs associated to MDS is heterogeneous, steroid sensitive, but often steroid dependent.

Screening of 145 anti-PrP monoclonal antibodies for their capacity to inhibit PrPSc replication in infected cells.

Prion diseases are transmissible neurodegenerative disorders affecting humans and animals for which no therapeutic or prophylactic regimens exist. During the last three years several studies have shown that anti-PrP monoclonal antibodies (mAbs) can antagonize prion propagation in vitro and in vivo, but the mechanisms of inhibition are not known so far. To identify the most powerful mAbs and characterize more precisely the therapeutic effect of anti-PrP antibodies, we have screened 145 different mAbs produced in our laboratory for their capacity to cure cells constitutively expressing PrPSc. Our results confirm for a very large series of antibodies that mAbs recognizing cell-surface native PrPc can efficiently clean and definitively cure infected cells. Antibodies having a cleaning effect are directed against linear epitopes located in at least four different regions of PrP, suggesting an epitope-independent inhibition mechanism. The consequence of antibody binding is the sequestration of PrPc at the cell surface, an increase of PrPc levels recovered in cell culture medium, and an internalization of antibodies. Taken together these data suggest that the cleaning process is more likely due to a global effect on the PrP trafficking and/or transconformation process. Two antibodies, Sha31 and BAR236, show an IC50 of 0.6 nM, thus appearing 10-fold more efficient than previous antibodies described in the literature. Finally, five co-treatments were also tested, and only one of them, described previously (SAF34 + SAF61), lowered PrPSc levels in the cells synergistically.