Determination of plasma concentration of Belimumab by LC-MS/MS: Method development, validation, and clinical application.

INTRODUCTION: Belimumab is a monoclonal antibody against B cell activating factor (BLyS). This monoclonal antibody (mAb) has been shown to be effective in reducing disease activity in patients with systemic lupus erythematosus (SLE). Belimumab is available in two forms as a lyophilized powder for intravenous (IV) use, or single-dose syringe for subcutaneous (SC) use. The aim of this study was to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantitation of belimumab in human serum. MATERIAL AND METHODS: All analyses relied on nano-surface and molecular-orientation limited (nSMOL) proteolysis coupled with LC-MS/MS. Quantifications was performed in multiple reactions monitoring (MRM) mode, and electrospray ionization was conducted in positive mode. RESULTS: Belimumab was quantified with signature peptide QAPGQGLEWMGGIPFGTAK and normalized using P14R. The total run time per assay was 10 min. Linearity was measured from 5 to 800 µg/mL (r² > 0.995). Accuracy and precision based on three quality control levels range from 11.2 - 9.51 % and 1.24 - 13.12 % respectively. The carryover was less than 7 %. In all, 87 patient samples were processed (65, IV; 22, SC). Mean concentration of belimumab was significantly higher for SC (93.0 ± 74.0 µg/mL) than for IV (67.4 ± 38.9 µg/mL) administration. CONCLUSION: We have developed the first method of belimumab quantification combining LC-MS/MS and nSMOL proteolysis. It can be used for future clinical pharmacokinetic studies of belimumab and for investigating the relationship between belimumab concentration, efficacy, and toxicity in SLE patients.

Pre-COVID-19 Immunity to Common Cold Human Coronaviruses Induces a Recall-Type IgG Response to SARS-CoV-2 Antigens Without Cross-Neutralisation.

The capacity of pre-existing immunity to human common coronaviruses (HCoV) to cross-protect against de novo COVID-19is yet unknown. In this work, we studied the sera of 175 COVID-19 patients, 76 healthy donors and 3 intravenous immunoglobulins (IVIG) batches. We found that most COVID-19 patients developed anti-SARS-CoV-2 IgG antibodies before IgM. Moreover, the capacity of their IgGs to react to beta-HCoV, was present in the early sera of most patients before the appearance of anti-SARS-CoV-2 IgG. This implied that a recall-type antibody response was generated. In comparison, the patients that mounted an anti-SARS-COV2 IgM response, prior to IgG responses had lower titres of anti-beta-HCoV IgG antibodies. This indicated that pre-existing immunity to beta-HCoV was conducive to the generation of memory type responses to SARS-COV-2. Finally, we also found that pre-COVID-19-era sera and IVIG cross-reacted with SARS-CoV-2 antigens without neutralising SARS-CoV-2 infectivity in vitro. Put together, these results indicate that whilst pre-existing immunity to HCoV is responsible for recall-type IgG responses to SARS-CoV-2, it does not lead to cross-protection against COVID-19.

Rituximab-associated Vasculitis Flare: Incidence, Predictors, and Outcome.

OBJECTIVE: To report the incidence, predictors, and outcome of rituximab (RTX)-associated autoimmune disease flare. METHODS: We conducted a retrospective study in a tertiary referral center from 2005 to 2015. Disease flare was defined as the onset of a new organ involvement or worsening of autoimmune disease within 4 weeks following RTX. RESULTS: Among the 185 patients, we identified 7 disease flares (3.4%). All were due to type II mixed cryoglobulinemia vasculitis. Vasculitis flare occurred after a median time of 8 days (range 2-16) following RTX infusion and included acute kidney insufficiency (n = 7), purpura with cutaneous (n = 7), gastrointestinal (GI) tract involvement (n = 4), and myocarditis (n = 1). Patients with RTX-associated cryoglobulinemia vasculitis flare had these conditions more frequently: renal involvement (p = 0.0008), B cell lymphoproliferation (p = 0.015), higher level of cryoglobulin (2.1 vs 0.4 g/l, p = 0.0004), and lower level of C4 (0.02 vs 0.05, p = 0.023) compared to patients without flare after RTX (n = 43). Four patients (57%) died after a median time of 3.3 months. The 1-year survival rate was poorer in patients with vasculitis flare after RTX compared to their negative counterpart [43% (95% CI 18-100) vs 97% (95% CI 92-100), p < 0.001]. Immunofluorescence analysis of kidney biopsy in patients with worsening RTX-associated vasculitis highlighted the presence of RTX-, IgM-, and IgG1-positive staining of endomembranous deposits and thrombi within kidney lesions. CONCLUSION: RTX-associated cryoglobulinemia vasculitis flare is associated with high mortality rate. We provided evidence that kidney lesions are due to immune complex deposition and to glomerular obstruction by cryoglobulinemia and RTX.

Safety and effectiveness of transjugular renal biopsy for systemic lupus erythematosus and antiphospholipid antibody syndrome patients taking antithrombotics.

BACKGROUND: Renal biopsy is the cornerstone of systemic lupus erythematosus (SLE) nephritis and antiphospholipid syndrome (APS) nephropathy management. However, transcutaneous renal biopsy (TCRB) is hampered by the antithrombotic treatment frequently prescribed for those diseases. Transjugular renal biopsy (TJRB) offers an attractive alternative for patients at increased risk of bleeding. The primary objective of the study was to describe the safety profile and diagnostic performance of TJRB in SLE and APS patients. METHODS: All SLE and/or APS patients who underwent a renal biopsy in our department (between January 2004 and October 2016) were retrospectively reviewed. Major complications were death, haemostasis nephrectomy, renal artery embolization, red blood cell transfusion, sepsis and vascular thrombosis; macroscopic haematuria, symptomatic perirenal/retroperitoneal bleeding and renal arteriovenous fistula without artery embolization were considered as minor complications. RESULTS: Two hundred and fifty-six TJRBs-119 without antithrombotics (untreated), 69 under aspirin and 68 on anticoagulants and 54 TCRBs without antithrombotics-were analysed. Their major and minor complication rates, respectively, did not differ significantly for the four groups: 0 and 8% for untreated TJRBs, 1 and 6% for aspirin-treated, 6 and 10% for anticoagulant-treated and 2 and 2% for TCRBs. The number of glomeruli sampled and the biopsy contribution to establishing a histological diagnosis was similar for the four groups. CONCLUSIONS: TJRBs obtained from SLE and APS patients taking antithrombotics had diagnostic yields and safety profiles similar to those of untreated TCRBs. Thus, TJRB should be considered for SLE and APS patients at risk of bleeding.

Infliximab biosimilar for treating neurosarcoidosis: tolerance and efficacy in a retrospective study including switch from the originator and initiation of treatment.

OBJECTIVES: Infliximab is increasingly used to treat neurosarcoidosis. We aimed to determine the efficacy and tolerance of an infliximab biosimilar for treating neurosarcoidosis. METHODS: We conducted a retrospective single-center study to describe the efficacy, safety and immunogenicity of an infliximab biosimilar in neurosarcoidosis patients. We compared the survival time without relapse while receiving the biosimilar or previous originator-infliximab treatment. RESULTS: Twenty patients with histologically documented neurosarcoidosis were treated with an infliximab biosimilar (initiation of treatment in 12 and switch from the originator drug in 8) between February 2016 and August 2018. All patients presenting with neurological involvement of one or more areas, including meningeal (n = 15), cerebral (n = 10), spinal cord (n = 9), and/or cranial nerves (n = 5); epilepsy (n = 3); and/or intracranial hypertension (n = 3) were enrolled. Eighteen patients received glucocorticoids during infliximab treatment, and 16 had methotrexate or azathioprine concomitant treatment. The median duration of follow-up was 25 months (19-28). Six patients relapsed during biosimilar treatment. Relapse rates and time-to-relapse did not differ between the infliximab originator previously received and biosimilar treatment groups (p = 0.40 and 0.51, respectively). Nine patients experienced 11 adverse events with the infliximab biosimilar, including infections (n = 5), urticaria (n = 4), headache (n = 1), and diarrhea (n = 1). All side effects were grade 2 or less using the WHO classification. CONCLUSIONS: In this retrospective study, the infliximab biosimilar was efficacious and safe for treating neurosarcoidosis.

Reproducible and sustained efficacy of targeted therapy with vemurafenib in patients with BRAF(V600E)-mutated Erdheim-Chester disease.

PURPOSE: Histiocytoses are rare disorders with heterogeneous prognosis. BRAF(V600E) mutations have been observed in half of patients with Langerhans cell histiocytosis (LCH) and in 50% to 100% of patients with Erdheim-Chester disease (ECD) patients. We recently reported short-term efficacy of a BRAF inhibitor (vemurafenib) in three patients with multisystemic ECD. PATIENTS AND METHODS: Vemurafenib was given to eight patients with multisystemic ECD with CNS and/or cardiac involvement. All patients were refractory to first-line treatment and harbored a BRAF(V600E) mutation. Four patients also had LCH lesions. Positron emission tomography (PET) scan response at month 6 was used as the main evaluation criterion. Secondary evaluation criteria were comparison at baseline and at last visit of PET and of cardiovascular and cerebral infiltrations (computed tomography scan and magnetic resonance imaging [MRI]). RESULTS: All patients were partial metabolic responders at 6 months of vemurafenib, and the median reduction in maximum standardized uptake value was 63.5% (range, 41.3% to 86.9%). Evaluation of cardiac and aortic infiltrations showed that seven patients had a partial response and one patient had stable disease according to surface measurements derived from RECIST criteria. The four patients with infratentorial CNS infiltration had an objective decrease of the lesions on MRI. All patients had an improvement of general symptoms and a persistent response to vemurafenib, with a median follow-up time of 10.5 months (range, 6 to 16 months). Skin adverse effects were frequent and severe. CONCLUSION: Vemurafenib has an objective and sustained efficacy in BRAF(V600E)-mutated ECD as second-line therapy. In contrast to melanoma, no resistance has emerged to date after 6 to 16 months.

Dramatic efficacy of vemurafenib in both multisystemic and refractory Erdheim-Chester disease and Langerhans cell histiocytosis harboring the BRAF V600E mutation.

Histiocytoses are rare disorders of unknown origin with highly heterogeneous prognosis. BRAFV600E gain-of-function mutations have been observed in 57% of cases of Langerhans cell histiocytosis (LCH) and 54% of cases of Erdheim-Chester disease (ECD), but not in other types of histiocytoses. Targeted therapy with an inhibitor of mutated BRAF (vemurafenib) improves survival of patients with melanoma. Here, we report vemurafenib treatment of 3 patients with multisystemic and refractory ECD carrying the BRAFV600E mutation; 2 also had skin or lymph node LCH involvement. The patients were assessed clinically, biologically (CRP values), histologically (skin biopsy), and morphologically (positron emission tomography [PET], computed tomography and magnetic resonance imaging). For all patients, vemurafenib treatment led to substantial and rapid clinical and biologic improvement, and the tumor response was confirmed by PET, computed tomography, and/or magnetic resonance imaging 1 month after treatment initiation. For the first patient treated, the PET response increased between months 1 and 4 of treatment. The treatment remained effective after 4 months of follow-up although persistent disease activity was still observed. Treatment with vemurafenib, a newly approved BRAF inhibitor, should be considered for patients with severe and refractory BRAFV600E histiocytoses, particularly when the disease is life-threatening.