Validation of an anti-α-Gal IgE fluoroenzyme-immunoassay for the screening of patients at risk of severe anaphylaxis to cetuximab.

BACKGROUND: The link between immediate hypersensitivity reactions (HSR) following the first cetuximab infusion and the IgE sensitization against anti-galactose-α-1,3-galactose (α-Gal) is now well-established. An automated Fluoroenzyme-Immunoassay (FEIA) is available and may facilitate the screening of patients with anti-α-Gal IgE before treatment. METHODS: This study aimed to evaluate its performances as compared to a previously validated anti-cetuximab IgE ELISA, using 185 samples from two previously studied cohorts. RESULTS: Despite 21.1% of discrepancies between the two techniques, FEIA discriminated better positive patients and similarly negative ones with a ≥ 0.525 kUA/L threshold. Sensitivity was 87.5% for both tests, specificity was better for FEIA (96.3% vs ELISA: 82.1%). FEIA had a higher positive likelihood ratio (23.9 vs ELISA: 4.89) and a similar negative likelihood ratio (0.13 vs ELISA: 0.15). In our population, the risk of severe HSR following a positive test was higher with FEIA (56.7% vs ELISA: 19.6%) and similar following a negative test (0.7% vs ELISA: 0.8%). CONCLUSION: Although the predictive value of the IgE screening before cetuximab infusion remains discussed, this automated commercial test can identify high-risk patients and is suitable for routine use in laboratories. It could help avoiding cetuximab-induced HSR by a systematic anti-α-Gal IgE screening before treatment.

The diagnostic challenge of patients with anti-U1-RNP antibodies.

Anti-U1-RNP antibodies are necessary for the diagnosis of mixed connective tissue disease (MCTD), but they are also prevalent in other connective tissue diseases, especially systemic lupus erythematosus (SLE), from which distinction remains challenging. We aimed to describe the presentation and outcome of patients with anti-U1-RNP antibodies and to identify factors to distinguish MCTD from SLE. We retrospectively applied the criteria sets for MCTD, SLE, systemic sclerosis (SSc) and rheumatoid arthritis (RA) to all patients displaying anti-U1-RNP antibodies in the hospital of Caen from 2000 to 2020. Thirty-six patients were included in the analysis. Eighteen patients (50%) satisfied at least one of the MCTD classifications, 11 of whom (61%) also met 2019 ACR/EULAR criteria for SLE. Twelve other patients only met SLE without MCTD criteria, and a total of 23 patients (64%) met SLE criteria. The most frequent manifestations included Raynaud's phenomenon (RP, 91%) and arthralgia (67%). We compared the characteristics of patients meeting only the MCTD (n = 7), SLE (n = 12), or both (n = 11) criteria. Patients meeting the MCTD criteria were more likely to display SSc features, including sclerodactyly (p < 0.01), swollen hands (p < 0.01), RP (p = 0.04) and esophageal reflux (p < 0.01). The presence of scleroderma features (swollen hands, sclerodactyly, gastro-oesophageal reflux), was significantly associated with the diagnosis of MCTD. Conversely, the absence of those manifestations suggested the diagnosis of another definite connective tissue disease, especially SLE.

Disease patterns and specific trajectories of anti-MDA5-related disease: a multicentre retrospective study of 70 adult patients.

Introduction: This study aimed to provide an updated analysis of the different prognostic trajectories of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibodies. Methods: Among a cohort of 70 patients, baseline characteristics and phenotypes, treatments and outcomes were analyzed. A Cox proportional hazards model was used to identify factors associated with poor outcomes, i.e., death or progressive disease at the last follow-up. Results: Among the 70 patients, 45 were women, and 54 were Caucasian. A dermatologic involvement was observed in 58 (83%) patients, including 40 with MDA5 vasculopathy-related skin lesions. Muscular involvement was observed in 39 (56%) patients. Interstitial lung disease (ILD) was observed at baseline in 52 (74%) patients, including 23 (44%) who developed rapidly progressive (RP) ILD. Seven (10%) patients showed thromboembolic complications within the first weeks of diagnosis, and eight (11%) other patients developed a malignancy (4 before the diagnosis of anti-MDA5 disease). Poor outcomes were observed in 28 (40%) patients, including 13 (19%) deaths. Among the 23 patients with RP-ILD, 19 (79%) showed poor outcomes, including 12 (63%) who died. In multivariate analyses, RP-ILD (hazard ratio (HR), 95% CI: 8.24 [3.21-22], p<0.0001), the occurrence of thromboembolic events (HR: 5.22 [1.61-14.77], p=0.008) and the presence of any malignancy (HR: 19.73 [6.67-60], p<0.0001) were the three factors independently associated with poor outcomes. Discussion: This new independent cohort confirms the presence of different clinical phenotypes of anti-MDA5 diseases at baseline and the poor prognosis associated with RP-ILD. Thromboembolic events and malignancies were also identified as prognostic factors.

[The detection of antithyroid antibodies in cerebrospinal fluid using fluorescent enzyme immuno assay (FEIA) is suitable for biological diagnosis of Hashimoto's encephalopathy]. / Détection des auto-anticorps antithyroïdiens dans le LCR par technique d'immunofluorométrie (FEIA) : application au diagnostic biologique de l'encéphalopathie d'Hashimoto.

Hashimoto encephalopathy (HE) is a rare condition often underdiagnosed. The clinical picture is heterogeneous with numerous neurological signs and is associated with the presence of high levels of anti-thyroperoxidase (TPO) and / or anti-thyroglobulin (TG) antibodies in the blood and cerebrospinal fluid (CSF). The determination of anti-TPO and anti-TG antibodies in CSF is performed in only few laboratories. The aim of our study was to adapt the EliATM fluoroenzymatic immuno assay (FEIA) to the detection of these autoantibodies in the CSF, and to compare the results with our previously published ELISA test (Blanchin S. 2007). For the FEIA technique, the detection threshold, and the quantification threshold have been determined for anti-TPO and anti-TG antibodies. FEIA results were concordant with ELISA at 75% and 100% for anti-TPO and anti-TG antibodies, respectively. Coefficients of variation (CV) of the intra-assay and inter-assay results were calculated as well as the uncertainties of measurement. The anti-TPO and anti-TG antibodies detection in CSF using FEIA technique correlate with the previously published ELISA and show good analytical performances. The availability of PhadiaTM 250 analyzer in a large number of laboratories will allow an easier biological detection. We hope that this test will respond to physician needs and help for HE diagnosis.

Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring.

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.

[Performance criteria for the verification of IgE and tryptase assay methods: recommendations from the AllergoBioNet network]. / Critères de performance pour la vérification des méthodes de dosages des IgE et de la tryptase : recommandations du réseau AllergoBioNet.

Accreditation of an in vitro diagnostic assay according to the NF/EN/ISO 15189 standard requires to analyze its technical performance before implementation for routine use, and annually when reviewing effectiveness of quality controls. Performance is evaluated through repeatability, intermediate fidelity, accuracy and uncertainty of measurement. The coefficients of variation (CV) of the intra-assay and inter-assay precision tests must be compared with those of "peers" (results from laboratories employing the same method) and also with those obtained with "all methods", i.e., results from all laboratories performing the same assay, irrespective of the method. To our best knowledge, there is currently no French or international recommendation on what the acceptable limits of performance for specific IgE and tryptase assays should be. Therefore, the AllergoBioNet network of hospital allergy laboratories set out to characterize the performance of their current methods as a basis for the development of recommendations. The results provided by 24 centers were analyzed and led to consensus recommendations for specific IgE, total IgE and tryptase assays.

Clinical Effect of Alpha-1 Antitrypsin Deficiency in Antineutrophil Cytoplasmic Antibody-associated Vasculitis: Results from a French Retrospective Monocentric Cohort.

OBJECTIVE: Deficiency in alpha-1 antitrypsin (AAT) is a possible pathogenic cofactor in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, the clinical effect of AAT deficiency remains poorly established in this setting. This study aimed to describe the clinical phenotypes and outcomes of AAV according to AAT phenotypes. METHODS: This study was conducted retrospectively at Caen University Hospital and included all consecutive granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) patients with positive proteinase 3-ANCA or myeloperoxidase-ANCA, from January 2000 or September 2011, respectively, to June 2016. AAT dosage (nephelometry) and phenotyping (isoelectric focusing in agarose gel) were performed. RESULTS: Among the 142 patients with AAV, including 88 GPA and 54 MPA, 102 (72%) had the MM phenotype, 5 (4%) had a nonpolymerogenic M-variant phenotype, 18 (13%) had the deficient allele MZ, 12 (8%) had MS, 2 (1%) had ZZ, 2 (1%) had SZ, and 1 (1%) had SS. M, Z, and S allele frequencies were 84%, 8%, and 6%, respectively. No association was observed between AAT deficiency and ANCA subtype or AAV phenotype, except for intraalveolar hemorrhage (IAH), which was more frequent in patients harboring at least 1 of the deficient Z or S alleles than in those without any deficient alleles (p < 0.01). Global, renal, or relapse-free survival rates were similar for all subgroups. CONCLUSION: This study shows that AAT deficiency confers, independently of ANCA subtype, a higher risk of IAH. Prospective studies are required to refine these data and to assess the need for replacement therapy in AAT-deficient patients with AAV.

Clinical impact of subgrouping ANCA-associated vasculitis according to antibody specificity beyond the clinicopathological classification.

OBJECTIVES: In ANCA-associated vasculitis (AAV), classifications have emerged to individualize homogeneous clinical and outcomes patterns, including the recently defined anti-MPO granulomatosis with polyangiitis (GPA) subgroup. This study aimed to retrospectively evaluate the impacts of re-classification based on clinicopathological criteria and/or ANCA specificity. METHODS: A retrospective monocentric study conducted at Caen University Hospital led to the identification of PR3 or MPO-ANCA AAV patients from January 2000 or September 2011, respectively, to June 2016. Eosinophilic GPA patients were excluded. AAVs were thereby also classified either as GPA or microscopic polyangiitis (MPA) according to the European Medicines Agency vasculitis algorithm. RESULTS: A total of 150 AAV patients were included (94 GPA, 56 MPA; 87 anti-PR3 and 63 anti-MPO patients). GPA patients exhibited a worse relapse-free survival but a better renal survival (P < 0.001 and P = 0.021, respectively) than MPA patients. Overall, relapse-free and renal survival rates were similar between anti-PR3 and anti-MPO patients (P = 0.35, 0.17 and 0.15, respectively). Similarly, the prognosis was identical between anti-MPO MPA patients and anti-PR3 MPA patients (P = 0.33, 0.19 and 0.65, respectively), and between anti-MPO GPA patients and anti-PR3 GPA patients (P = 0.06, 0.99 and 0.64, respectively). Moreover, anti-PR3 GPA and anti-MPO GPA patients exhibited no differences in clinical manifestations or BVAS score. CONCLUSION: Clinicopathological classification appeared to be the strongest criterion for distinguishing among homogeneous prognoses of AAV. Individualizing the anti-MPO GPA subgroup does not appear to bring additional value to clinical practice, but multicentre studies are required to confirm this trend.

Hypocomplementemia is associated with worse renal survival in ANCA-positive granulomatosis with polyangiitis and microscopic polyangiitis.

Recent data suggest the existence of a complement alternative pathway activation in the pathogenesis of antineutrophilic cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a condition that remains poorly understood. This study aims to assess the clinical characteristics and outcomes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) patients with regard to their plasma complement levels at diagnosis. A retrospective monocentric study carried out at Caen University Hospital led to the identification of proteinase-3- or myeloperoxidase-ANCA-positive GPA and MPA patients from January 2000 to June 2016 and from September 2011 to June 2016, respectively. All patients with available C3 and C4 levels at diagnosis were included. Patients were categorized in the hypocomplementemia group if their C3 and/or C4 levels at diagnosis were below the lower limit of the normal range. Among the 76 AAV patients (43 GPA, 33 MPA), 4 (5%) had hypocomplementemia, and the 72 remaining patients exhibited normal plasma complement levels. All 4 hypocomplementemia patients had renal involvement. Hypocomplementemia was followed in 1 patient whose post-treatment complement level normalized within 1 month. Among all clinical and ANCA specificity, including relapse-free survival (p = 0.093), only overall and renal survival rates were significantly lower in the hypocomplementemia group (p = 0.0011 and p<0.001, respectively). Hypocomplementemia with low C3 and/or C4 levels at GPA or MPA diagnosis may be responsible for worse survival and renal prognosis. These results argue for larger and prospective studies to better determine the epidemiology of the disease and to assess complement-targeting therapy in these patients.

In Vivo Cysteinyl Leukotriene Release in Allergic and Nonallergic Immediate Hypersensitivity Reactions during Anesthesia.

BACKGROUND: Immediate hypersensitivity reactions occurring during anesthesia are classified as allergic when skin tests and mast cell tryptase are positive and as nonallergic when negative results are obtained. Cysteinyl leukotrienes (cysLTs) are potent mediators synthesized by mast cell and eosinophil that induce bronchial constriction. They could play a role in hypersensitivity reactions. METHODS: cysLT C4, D4, and E4 concentrations were measured by a competition immunoassay in serial plasma samples obtained prospectively from 21 anesthetized controls and retrospectively from 34 patients who reacted at induction of anesthesia (24 with allergic and 10 with nonallergic reactions). RESULTS: In controls, the median (interquartile range) cysLT concentration was 0.83 (0.69 to 1.02) µg/l before anesthesia and was unchanged 30 min, 6 h, and 24 h afterward. In the patients with allergic reactions, the values were highly increased 30 to 60 min after the reaction (17.9 [7.8 to 36.0] µg/l), while the patients with nonallergic reactions had less increased values (7.3 [3.0 to 11.5] µg/l). The difference between the three groups was significant (P < 0.0001). Increased values persisted during the 24 h of observation. Concentrations were significantly higher in patients with bronchospasm (P = 0.016). CONCLUSIONS: cysLTs appear to be an important mediator of allergic and nonallergic immediate hypersensitivity reactions. These findings might open a new field for management of patients with hypersensitivity reactions, especially nonallergic ones.

Utility of serum anti-cetuximab immunoglobulin E levels to identify patients at a high risk of severe hypersensitivity reaction to cetuximab.

AIM: Cetuximab is an anti-epidermal growth factor receptor antibody used for the treatment of metastatic colorectal cancer and head and neck cancer. Hypersensitivity reactions (HSRs) are associated with cetuximab use. The aim of the study was to evaluate the utility of anti-cetuximab immunoglobulin E (IgE) detection in order to identify patients at risk of HSR to cetuximab. METHODS: We included patients ready to receive a first cetuximab infusion in a prospective cohort carried out at nine French centres. Pretreatment anti-cetuximab IgE levels were measured. We compared the proportion of severe HSRs in the low anti-cetuximab IgE levels (≤29 IgE arbitrary units) subgroup with that in a historical cohort of 213 patients extracted from a previous study. RESULTS: Of the 301 assessable patients (mean age: 60.9 ± 9.3 years, head-and-neck cancer: 77%), 66 patients (22%) had high anti-cetuximab IgE levels, and 247 patients received cetuximab (including 38 with high anti-cetuximab levels). Severe HSRs occurred in eight patients (five grade 3 and three grade 4). The proportion of severe HSRs was lower in the low anti-cetuximab IgE levels subgroup vs. the historical cohort (3/209 [1.4%] vs. 11/213 [5.2%], odds ratio, 0.27, 95% confidence interval, 0.07-0.97), and higher in high vs. low anti-cetuximab IgE levels subgroup (5/38 [13.2%] vs. 3/209 [1.4%]; odds ratio, 10.4, 95% confidence interval, 2.4-45.6). Patients with severe HSRs had higher anti-cetuximab IgE levels than patients without reaction (median, 45 vs. 2 IgE arbitrary units, P = 0.006). CONCLUSIONS: Detection of pretreatment anti-cetuximab IgE is feasible and helpful to identify patients at risk of severe cetuximab-induced HSRs.

Diagnostic procedure after an immediate hypersensitivity reaction in the operating room.

The diagnosis of a perioperative allergic reaction is based on clinical features associated with a suggestive timeline, the exclusion of other diagnoses, elevated concentrations of degranulation markers (histamine, tryptase), and positive allergy assessments (skin tests, specific IgE). After initiating appropriate treatment, the anesthesiologist should take blood samples to measure histamine and tryptase concentrations just after the reaction and repeat them 1-2hours later to validate the diagnosis of immediate hypersensitivity. A delayed measurement of basal tryptase is useful to rule out mastocytosis and to interpret moderate tryptase levels. The anesthesiologist must inform the patient of the reaction to obtain adhesion and consent to subsequent investigations and must record the timing of the reaction and of the blood sampling, the possible causal agents, and the treatment administered. These data must be shared with the laboratory and the allergist. An adverse drug reaction report must be filed. The gold standard for allergy assessment is skin testing. These tests should be done in an appropriate facility, with experienced staff and in compliance with current guidelines. Specific IgE assays and cellular assays can help when clinical features and skin tests are discordant. Provocation tests are sometimes required. After allergy assessment, the safest protocol for subsequent anesthesia is determined in collaboration with the anesthesiologist. The patient must be informed and carry an allergy alert card.

Risk factors associated with hypersensitivity reactions to cetuximab: anti-cetuximab IgE detection as screening test.

AIM: To describe the factors associated with a high risk of a hypersensitivity reaction to cetuximab. PATIENTS & METHODS: We retrospectively studied a cohort of patients living in Normandy (France) treated with cetuximab. RESULTS: Among the 229 treated patients, 24 (10.5%) had a hypersensitivity reaction to cetuximab, including 11 grade 3-5 reactions. Detection of anti-cetuximab IgE could be performed in 108 patients. Anti-cetuximab IgE was found in 13 of 17 patients (76.5%) who had a hypersensitivity reaction to cetuximab compared with 17 of 91 control patients (18.7%; adjusted odds ratio: 14.99; 95% CI: 3.59-62.63). No clinical criteria predicted the risk of allergy to cetuximab. CONCLUSION: Anti-cetuximab IgE may help physicians identify patients at risk of a hypersensitivity reaction to cetuximab.

Case Report About Fatal or Near-Fatal Hypersensitivity Reactions to Cetuximab: Anticetuximab IgE as a Valuable Screening Test.

Hypersensitivity reactions are a classic side effect of cetuximab. We report the cases of three patients who developed life-threatening hypersensitivity to cetuximab, which could have been predicted by assessing the concentration of serum anticetuximab immunoglobulin (Ig)E. The anticetuximab IgE concentration could be an interesting test to predict which patients are at risk of experiencing severe hypersensitivity reactions to cetuximab.

CD49d expression as a promising biomarker to monitor natalizumab efficacy.

Natalizumab (Tysabri™), a monoclonal antibody against the α4-integrin of VLA-4 (CD49d) antigen of leukocytes, is highly effective in multiple sclerosis (MS). The most common reason for treatment failure is the development of neutralizing antibodies (NAbs). According to health authorities Nabs testing is recommended in case of relapse or repeated infusion reactions. However NAbs may develop in clinically asymptomatic patients. In this study we investigated if CD49d expression could serve as a biomarker of natalizumab bioavailability and treatment response. In a cohort of 49 natalizumab treated relapsing-remitting MS, followed over 2 years, CD49d expression was determined on peripheral blood mononuclear cells (PBMCs) before each infusion and compared to NAbs and serum natalizumab levels. In a majority of patients (41/49) the CD49d expression in PBMCs was strongly inhibited (>50%) after the first infusion and maintained at low levels throughout the treatment period. In contrast, in eight patients (16%) there was an early recovery of CD49d expression to pre-treatment levels related to NABs development. While three cases experienced hypersensitivity reactions, three others were identified solely on the basis of an undiminished level of CD49d, with neither infusion reaction nor clinical worsening. These 3 patients had very high levels of NAbs and no detectable serum natalizumab. Two additional patients had early but transient recovery of CD49d expression. These patients had low levels of transient Nabs and returned to significant CD49d inhibition after few natalizumab infusions. We suggest that monitoring of CD49d expression can be used as a surrogate biomarker of natalizumab efficiency. If the CD49d expression is sustained at pre-treatment levels, patients should be tested for persistent NAbs and considered for treatment interruption.