key: cord-0991050-uxicb5y1
authors: Fattizzo, Bruno; Giannotta, Juri Alessandro; Cecchi, Nicola; Barcellini, Wilma
title: SARS‐CoV‐2 vaccination induces breakthrough hemolysis in paroxysmal nocturnal hemoglobinuria on complement inhibitor
date: 2021-05-31
journal: Am J Hematol
DOI: 10.1002/ajh.26262
sha: e6dba044096616b90771962d97c5caff2cd54d5c
doc_id: 991050
cord_uid: uxicb5y1

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This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ajh.26262 This article is protected by copyright. All rights reserved.

To the Editor, SARS-CoV-2 infection and vaccination have raised concern in complement mediated hemolytic anemias (i.e. paroxysmal nocturnal hemoglobinuria, PNH, and cold agglutinin disease, CAD), particularly if on treatment with complement inhibitors [1] [2] [3] . Among complement amplifying triggers (infections, traumas, and surgery [4, 5] ) an emerging causative agent may be SARS-CoV-2 vaccines. In PNH patients on complement inhibitors, pharmacodynamic breakthrough hemolysis (BTH) has been defined as hemolysis reactivation with hemoglobin drop due to increased complement activity [6] . In CAD, where complement inhibitors are in clinical trials, a true BTH has not been defined yet, although hemolytic flares have been described under treatment [7] . Gerber et al [5] recently reported 6 PNH patients, either untreated or on complement inhibitors, who experienced abrupt hemolytic crisis following SARS-CoV-2 vaccination (4 Pfizer-BioNTech and 2 Moderna vaccine). Five patients were on intravenous ravulizumab and developed BTH after either the first (N=1), the second (N=2), or after both doses (N=2) of vaccine. Two patients were also receiving oral factor D inhibitor danicopan, and one experienced BTH only after the second dose, after interruption of danicopan (2 missed doses) due to concerns about interaction with vaccine efficacy. Pérez-Lamas et al described a hemolytic crisis occurring two days after the first dose of an mRNA Covid-19 vaccination in a CAD patient not under complement inhibition [8] . Here we describe a classic hemolytic PNH patient on C5 inhibitor, who developed severe BTH one day after the second dose of Moderna SARS-CoV-2 vaccine. This patient belongs to a cohort of 16 patients (13 PNH and 3 CAD) who received mRNA SARS-CoV-2 vaccine from March 2021. All them were actively treated with complement inhibitors (5 eculizumab, 3 intravenous ravulizumab, 4 subcutaneous ravulizumab, 1 factor B inhibitor iptacopan, and 3 C1s inhibitor sutimlimab) at our Hematology unit in Milan, Italy. The study was conducted in accordance with Helsinki Declaration and patients gave informed consent.

A 45-year-old lady suffering from PNH presented to the emergency room on April, 21 the day after receiving the second dose of Moderna mRNA SARS-CoV-2 vaccine. The patient had a diagnosis of classic hemolytic PNH since 1996 and was on C5 complement inhibition from 2016 with suboptimal response and complete control of hemolysis (average Hb 9.5 g/dL with normal LDH, inadequate reticulocytosis). Since 2019 she has been enrolled in a clinical trial with subcutaneous ravulizumab, administered weekly. The patient had had no side effects following her first dose of the Moderna vaccine (March, 24). At presentation, she complained hyperpyrexia (38.8°C) and several episodes of vomiting, abdominal pain and dark urine. Vital signs were normal and blood counts (supplementary figure 1) displayed severe anemia with significant intravascular hemolysis (LDH 2.3 x ULN), consistent with BTH. Moderate neutropenia (0.83x10^9/L), and mild thrombocytopenia (100x10^9/L) were also noted, along with slightly increased C reactive protein (3.6 mg/dL), prolonged prothrombin time ratio (1.46), and increased D dimer (895 mcg/L). Molecular testing on nasopharyngeal swab for SARS-CoV-2 was negative, as well as chest X-ray, blood and urine cultures. The patient was started on intravenous antibiotics, hydration, and paracetamol with progressive amelioration of symptoms, and admitted to the hematology ward. BTH persisted, and low molecular weight heparin was started. On day+4 from presentation, Hb dropped to 6.7 g/dL with suboptimal reticulocyte counts (106x10^9/L). Recombinant human erythropoietin (rhEPO, epoetin alpha 40,000 UI subcutaneously) was administered with hematological improvement and repeated on day+14. Of note, subcutaneous ravulizumab was regularly continued along admission.

The occurrence of post-vaccine BTH in PNH patients should not discourage vaccination of this population. In fact, whilst COVID-19 may be fatal and difficult to handle [1, 2] , BTH is more known and seems manageable with supportive care, as in the case reported. In our patient, neutropenia deserved hospital admission, and recombinant erythropoietin was helpful to improve anemia avoiding transfusions. Moreover, the prompt recognition of BTH is pivotal, since, besides anemia, active intravascular hemolysis puts patients at higher risk of thrombosis, through various mechanisms including free Hb release and nitric oxide depletion with consequent endothelial dysfunction [6] . Of note, increased thrombotic risk is also reported in CAD, although its management has not been clearly established. Thrombotic risk may be even higher during COVID-19, and after certain SARS-CoV-2 vaccines that may mimic autoimmune heparininduced thrombocytopenia [9] . In our patient, prophylaxis with LMWH was therefore instituted and no thrombosis occurred.

Regarding the mechanisms of post-vaccine BTH, it has been described that SARS-CoV-2 spike protein may bind on nucleated cells and amplify complement alternative pathway by interfering with factor H [10] . However, the addition of spike protein subunit 1 did not increase lysis of PNH erythrocytes ex vivo [5] , and did not appear to bind red cells, weakening the hypothesis of a direct vaccine effect on erythrocytes. On the contrary, complement amplification triggered by the inflammatory/immune response following vaccine seems prominent. In our patient, no BTH was reported after the first vaccine administration, suggesting a pivotal role of higher immune response following the "booster" dose. In keeping with this hypothesis, pharmacodynamic BTH has been observed even after ravulizumab that has a half-life four times longer than eculizumab and is associated with reduced pharmacokinetic BTH events [11] . On the other hand, a protective effect of proximal complement inhibitors (i.e. C1-, C3-, factor D and factor B inhibitors) may be hypothesized, although definite data are not available. Consistently, no hemolytic events occurred after either vaccine doses in the 3 CAD patients on C1s inhibitor sutimlimab at our center.

Concerning timing of administration, in the experience by Gerber et al [5] , all patients had received ravulizumab > 4 weeks before vaccine, suggesting that administration of SARS-CoV-2 vaccination may be safer within 4 weeks from the last ravulizumab. However, our patient had received weekly subcutaneous ravulizumab the day immediately before both vaccine doses. It is therefore difficult to advise a proper timing of vaccine administrations, and close monitoring and patient education remain the only mandatory procedures.

In conclusion, this report shows that hemolytic flares may occur after SARS-CoV-2 vaccines and should be promptly recognized and managed through medical suspicion, patient education, and clinical monitoring.

COVID-19 infection in patients on anti-complement therapy: The Leeds National Paroxysmal Nocturnal Hemoglobinuria service experience

Severe COVID-19 infection in a patient with paroxysmal nocturnal hemoglobinuria on eculizumab therapy

Are Patients With Autoimmune Cytopenias at Higher Risk of COVID-19 Pneumonia? The Experience of a Reference Center in Northern Italy and Review of the Literature. Front Immunol

Complement Activation and Inhibition in Autoimmune Hemolytic Anemia: Focus on Cold Agglutinin Disease

COVID-19 Vaccines Induce Severe Hemolysis in Paroxysmal Nocturnal Hemoglobinuria

Anti-complement Treatment for Paroxysmal Nocturnal Hemoglobinuria: Time for Proximal Complement Inhibition? A Position Paper From the SAAWP of the EBMT. Front Immunol

Sutimlimab in Cold Agglutinin Disease

Hemolytic crisis due to Covid-19 vaccination in a woman with cold agglutinin disease

Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination

Direct activation of the alternative complement pathway by SARS-CoV-2 spike proteins is blocked by factor D inhibition

Characterization of breakthrough hemolysis events observed in the phase 3 randomized studies of ravulizumab versus eculizumab in adults with paroxysmal nocturnal hemoglobinuria

Role of the funding source: No funding sources to declare.

All Authors declare that they have no conflict of interest to disclose.Author contributions: All Authors followed patients, wrote the article and revised it for important intellectual content.