A Significant Contribution of the Classical Pathway of Complement in SARS-CoV-2 Neutralization of Convalescent and Vaccinee Sera.

Although high titers of neutralizing Abs in human serum are associated with protection from reinfection by SARS-CoV-2, there is considerable heterogeneity in human serum-neutralizing Abs against SARS-CoV-2 during convalescence between individuals. Standard human serum live virus neutralization assays require inactivation of serum/plasma prior to testing. In this study, we report that the SARS-CoV-2 neutralization titers of human convalescent sera were relatively consistent across all disease states except for severe COVID-19, which yielded significantly higher neutralization titers. Furthermore, we show that heat inactivation of human serum significantly lowered neutralization activity in a live virus SARS-CoV-2 neutralization assay. Heat inactivation of human convalescent serum was shown to inactivate complement proteins, and the contribution of complement in SARS-CoV-2 neutralization was often >50% of the neutralizing activity of human sera without heat inactivation and could account for neutralizing activity when standard titers were zero after heat inactivation. This effect was also observed in COVID-19 vaccinees and could be abolished in individuals who were undergoing treatment with therapeutic anti-complement Abs. Complement activity was mainly dependent on the classical pathway with little contributions from mannose-binding lectin and alternative pathways. Our study demonstrates the importance of the complement pathway in significantly increasing viral neutralization activity against SARS-CoV-2 in spike seropositive individuals.

Renal Thrombotic Microangiopathy: A Review.

Thrombotic microangiopathy (TMA), a pathological lesion observed in a wide spectrum of diseases, is triggered by endothelial injury and/or dysfunction. Although TMA lesions are often accompanied by clinical features of microangiopathic hemolytic anemia, thrombocytopenia, and ischemic end-organ injury, renal-limited forms of TMA are not infrequently encountered in clinical practice. The presence of renal-limited manifestations can be diagnostically challenging, often delaying the initiation of targeted therapy. Prompt investigation and empirical treatment of TMA is warranted to reduce associated morbidity and mortality. Major advances have been made with respect to the pathophysiology of primary TMA entities, with the subsequent development of novel diagnostic tools and lifesaving therapies for diseases like thrombotic thrombocytopenic purpura and complement-mediated TMA. This article will review the clinical presentation and pathologic hallmarks of TMA involving the kidney, and the disease-specific mechanisms that contribute to the endothelial injury that characterizes TMA lesions. Diagnostic approach and both empirical and disease-specific treatment strategies will be discussed, along with the potential role for emerging targeted disease-specific therapies.

Risk factors for thromboembolic events in patients with paroxysmal nocturnal hemoglobinuria (PNH): a nested case-control study in the International PNH Registry.

The objective of this analysis was to identify risk factors for thromboembolic events (TE) in patients with paroxysmal nocturnal hemoglobinuria (PNH) who were not treated with C5 inhibitors. Patients with PNH and a history of ≥ 1 TE at enrollment in the International PNH Registry (NCT01374360; registration date, January 2011) were each matched with up to 5 patients without TE. Multivariable analysis was performed with the following variables: percentage glycosylphosphatidylinositol (GPI)-negative cells, high disease activity (HDA), non-TE major adverse vascular event history, and recent anticoagulation. Of 2541 eligible patients, 57 with TE and 189 matched controls were analyzed. Multivariable analysis (odds ratio [95% CI]) identified the following factors as being associated with increased thrombotic risk: patients with no history of TE (with recent anticoagulation, 9.30 [1.20-72.27]), patients with history of TE (with recent anticoagulation, 8.91 [0.86-92.62]; without recent anticoagulation, 5.33 [0.26-109.57]), patients with ≥ 30% GPI-negative granulocytes (≥ 30% to < 50%, 4.94 [0.54-45.32]; ≥ 50%, 1.97 [0.45-8.55]), or patients with lactate dehydrogenase (LDH) ratio ≥ 1.5 × upper limit of normal (ULN) plus ≥ 2 HDA criteria (2-3 criteria, 3.18 [0.44-23.20]; ≥ 4 criteria, 3.60 [0.38-33.95]). History of TE, ≥ 30% GPI-negative granulocytes, and LDH ratio ≥ 1.5 × ULN with ≥ 2 HDA criteria are TE risk factors for patients with PNH. These findings will aid physicians by providing important clinical and laboratory risk factors that can be used to identify and manage patients with PNH who are at risk of developing TE.

Fatigue and health-related quality of life in paroxysmal nocturnal haemoglobinuria: A post hoc analysis of the pegcetacoplan PEGASUS trial data.

OBJECTIVES: Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, non-malignant haematological disorder associated with disabling fatigue and reduced health-related quality of life. Post hoc analysis of PEGASUS phase 3 trial (NCT03500549) characterised improvements in patient-reported fatigue measured by functional assessment of chronic illness therapy-fatigue (FACIT-fatigue) instrument item-level ratings for pegcetacoplan and eculizumab for the treatment of PNH. METHODS: Item-level responder analysis was conducted on a ≥2-level change from baseline (CFB) clinically important response (CIR) for the FACIT-fatigue 13 individual items rated on a 5-level Likert scale. We evaluated ≥2-level change against the minimal clinically important difference (MCID) of the FACIT-fatigue total score (≥5 points) and clinical parameters, haemoglobin (Hb; ≥1 g/dL) and normalised absolute reticulocyte count (ARC; 30-100 pg/cells). Logistic regressions estimated baseline-to-Week-16 FACIT-fatigue item-level transitional probabilities; Kaplan-Meier analysis estimated time to FACIT-fatigue item CIR. RESULTS: Pegcetacoplan versus eculizumab was associated with significantly greater odds of Week 16 CIR across 8/13 items and on total score MCID (OR [CI] = 11.19 [3.73, 33.57]) and faster times to responses. The item-level CIR threshold also showed clinical relevance on Hb level and ARC normalization. CONCLUSIONS: Compared with eculizumab, pegcetacoplan was associated with clinically meaningful greater improvements on a majority of FACIT-fatigue items.

Long-term effectiveness of eculizumab: Data from the International PNH Registry.

OBJECTIVES: Data from the International PNH Registry (NCT01374360) were used to estimate the overall survival and first occurrence of thromboembolic events/major adverse vascular events (TEs/MAVEs) for eculizumab-treated patients with paroxysmal nocturnal hemoglobinuria (PNH) compared with a contemporaneous untreated cohort. METHODS: Patients enrolled in the Registry from March 16, 2007, to February 14, 2022, were included. Treated patients received eculizumab for >35 days; untreated patients did not receive eculizumab at any time. Univariable and multivariable analyses were performed using a Cox proportional hazards regression model comparing eculizumab treatment periods to untreated periods and were adjusted for baseline covariates (e.g., high disease activity [HDA], transfusion dependency, and eculizumab treatment status). RESULTS: The analysis included 4118 patients. The univariable hazard ratio (HR) (95% CI) for mortality in eculizumab-treated time versus untreated time was 0.51 (0.41-0.64; p < 0.0001). Significant baseline covariates included age, sex, history of bone marrow failure, ≥4 erythrocyte transfusions within 12 months before baseline, and an estimated glomerular filtration rate ≤ 60 mL/min/1.73 m2 (all p < 0.0001). In the adjusted analysis, patients with baseline HDA had the greatest reduction in mortality risk (HR [95% CI], 0.51 [0.36-0.72]). Treated patients had approximately 60% reduction in TE/MAVE risk during treated versus untreated time (HR [95% CI]: TE: 0.40 [0.26-0.62], MAVE: 0.37 [0.26-0.54]; p < 0.0001). CONCLUSION: Using data from the largest Registry of patients with PNH, with ≥14 years of overall follow-up, we demonstrate that treatment with eculizumab conferred a 49% relative benefit in survival and an approximately 60% reduction in TE/MAVE risk.

Characterizing the process of urgent referrals and transfers to a large tertiary care apheresis centre in Ontario: A retrospective database review.

BACKGROUND: Therapeutic plasma exchange (TPE) and red blood cell exchange (RBCX) are life-saving apheresis procedures offered in 7 Ontario hospitals. Most referrals are directed by CritiCall Ontario (CritiCall), a 24/7 service funded by the Ontario Ministry of Health and Long-Term Care. We used CritiCall data to examine referral requests, acceptances, and transfers for urgent apheresis to our centre. METHODS: Retrospective CritiCall referral and transfer data for urgent apheresis between October 2013 and December 2018 were included. Continuous variables were analyzed by linear regression. Categorical variables were analyzed using nonparametric tests. RESULTS: Eighty-five cases (52 TPE, 33 RBCX) were identified. Median patient age was 52 years (interquartile range [IQR] 32) for TPE, 29 years (IQR 18) for RBCX. Most patients (58%) were female. Total time from referral to arrival at our centre was 243 (IQR 166) minutes. The greatest proportion of this total was from patient acceptance to arrival (169 [IQR 112] minutes). Median distance between referring and accepting centres was 39 (IQR 30) kilometres, with ground transportation used most often. Multiple linear regression examining factors that contribute to total time demonstrated that the number of physicians contacted prior to patient acceptance and inter-hospital distance were independently associated (p = 0.007 and p = 0.048, respectively). INTERPRETATION: Addressing modifiable factors to reduce time is important given that time to initiate treatment is associated with better outcomes. Quality improvement strategies should be aimed at coordinated provincial resource sharing, pairing referrals with nearest available apheresis centres, and creating efficiency in the interval between patient acceptance and arrival.

Therapeutic plasma exchange in alloimmune platelet refractoriness.

Patients with alloimmune platelet refractoriness can present complex clinical conundrums. Herein we describe a case of platelet refractoriness in the setting of combined HLA and HPA alloimmunization in a patient with acute myeloid leukemia and life-threatening bleeding. We discuss causative antibodies and compare prevailing therapeutic modalities. We highlight plasma exchange as a potentially feasible, repeatable, and personalized treatment option for patients with extensive platelet alloimmunization who require transfusion.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Ninth Special Issue.

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. In the Ninth Edition, the JCA Special Issue Writing Committee has incorporated systematic review and evidence-based approaches in the grading of evidence and categorization of apheresis indications to make recommendations on the use of apheresis in a wide variety of diseases and conditions. This edition has largely maintained the general layout and concept of a fact sheet introduced in the Fourth Edition (2007). Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease or medical condition. The Ninth Edition of the JCA Special Issue comprises 91 fact sheets and 166 graded and categorized indications. This includes seven new fact sheets, nine new indications on existing fact sheets, and eight changes in the category for existing indications. The Ninth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Clinical and laboratory predictors of fetal and neonatal alloimmune thrombocytopenia.

BACKGROUND: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is the most common cause of intracranial hemorrhage (ICH) in thrombocytopenic term infants. We investigated clinical and laboratory predictors of severe FNAIT in a tertiary care referral center. STUDY DESIGN AND METHODS: Retrospective cohort study over a 30-year period. We defined FNAIT as recurrence of neonatal thrombocytopenia in a subsequent pregnancy; and severe outcomes as any of: (1) a birth platelet count below 20 × 109 /L; (2) ICH or (3) fetal death. We used a generalized estimating equations analysis and classification tree analysis to identify risk factors for severe FNAIT in a subsequent pregnancy. RESULTS: During index pregnancies (n = 135 in 131 mothers), 71 infants (52.6%) had severe outcomes including a platelet count <20 × 109 /L (n = 45), fetal or neonatal ICH (n = 32), or fetal death (n = 4). During subsequent pregnancies (n = 72), 15 infants (20.8%) had severe outcomes including birth platelets <20 × 109 /L (n = 10), ICH (n = 2), or death (n = 3). Forty-two women (58.3%) received antenatal intravenous immune globulin (IVIG) during subsequent pregnancies. Eight mothers (n = 9 infants) had severe FNAIT outcomes despite receiving antenatal IVIG. Maternal antibodies to human platelet antigens (HPA) was the only independent predictor of severe FNAIT in a subsequent pregnancy (OR = 25.3, p = .004). Nevertheless, one of 43 infants from antibody-negative mothers had a severe outcome. CONCLUSIONS: The presence of anti-HPA is highly indicative of the diagnosis of severe FNAIT; however, we observed one infant who had severe FNAIT recurrence, defined using strict clinical criteria, without a maternal antibody. Improved diagnostic and therapeutic strategies are needed to prevent severe FNAIT in high-risk mothers.

Apheresis education in Canadian residency programs: A needs assessment.

Indications for therapeutic and donor apheresis continue to increase and expand into new domains of therapy. The level and amount of apheresis education in residency programs remains heterogeneous, which may translate into varying degrees of clinical confidence in providing care. The purpose of this study was to assess Canadian clinicians' perceptions of their apheresis training in order to help demonstrate a need for a concrete apheresis education in residency curricula. A 22-question survey was distributed to Canadian graduates who recently completed training (2013-2017) in the following specialties: hematology, nephrology, transfusion medicine, and hematologic pathology. Questions regarding clinician perception of their training were asked using a Likert scale. Fifty-seven survey responses (32% response rate) were obtained from recent graduates from hematology (29/57, 51%), nephrology (21/57, 37%), hematologic pathology (4/57, 7%) and transfusion medicine (3/57, 5%). Although most respondents (68%) received some form of apheresis exposure during residency, only 23% reported a formal apheresis rotation. Only 40% felt that the amount of time devoted to apheresis education was sufficient, and only four respondents (7%) felt confident providing independent apheresis care at the end of training. Overall, these findings suggest that a common, dedicated apheresis curriculum in these training programs could possibly increase knowledge and competence of trainees, and provide a more solid foundation in apheresis for future practice.

The practical integration of a hybrid model of ultrasound-guided peripheral venous access in a large apheresis center.

BACKGROUND: Apheresis treatments require adequate venous access using peripheral intravenous (PIV) catheterization or central venous catheters (CVC). Ultrasound-guided PIV (USGPIV) can be used to decrease the need of CVC insertions for apheresis procedures. METHOD: A hybrid model of USGPIV and standard of care (SOC) for PIV access was developed. Nurses performed USGPIV on all patients considered for PIV access if felt SOC PIV access was not possible. Information was collected regarding nurses' confidence with access, number of attempts required, site of access, complications, and need for CVC. RESULTS: In all, 226 PIV access attempts were made during a 2-month period. All apheresis procedure types were represented. A total 65% were accessed by SOC and 35% by USGPIV. USGPIV was successful on first try on 90% draw/inlet access and 87% successful on first try on return access. Access above the antecubital fossa was required in 31% of USGPIV for draw/inlet veins, and 22% of return veins. Nurses' confidence with accessing PIV was increased by USGPIV, based on 7-point Likert scale assessments. During the recording period, 2/226 (0.9%) apheresis procedures required a CVC. In a separate cohort of only hematopoietic progenitor cell collections, CVC insertion was required in 44/238 (18.5%) patients, in 7 months prior to adoption of USGPIV and 5/152 (3.3%) patients in 7 months following adoption of USGPIV. CONCLUSION: A hybrid model of using SOC and USGPIV for PIV access for apheresis procedures resulted in decreased need for CVC access, high levels of successful initial access attempts, and increased nursing confidence in PIV access.

How we treat paroxysmal nocturnal hemoglobinuria: A consensus statement of the Canadian PNH Network and review of the national registry.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by intravascular hemolysis, thrombophilia, and marrow failure. Its phenotype is due to absent or reduced expression of GPI-linked complement regulators and subsequent sensitivity of hematopoietic cells to complement-mediated damage and lysis. Introduction of the terminal complement inhibitor eculizumab drastically improved outcomes in PNH patients; however, despite this improvement, there remain several challenges faced by PNH patients and physicians who care for them. One of the most important is increasing awareness of the heterogeneity with which patients can present, which can lead to significant delays in recognition. Data from the Canadian PNH Registry are presented to demonstrate the variety of presenting symptoms. In Canada, geography precludes consolidation of care to just a few centers, so management is distributed across academic hospitals, linked together as the Canadian PNH Network. The Network over the last several years has developed educational programs and clinical checklists and has worked to standardize access to diagnostics across the country. Herein, we address some of the common diagnostic and therapeutic challenges faced by PNH physicians and give our recommendations. Gaps in knowledge are also addressed, and where appropriate, consensus opinion is provided.

Eculizumab in Pregnant Patients with Paroxysmal Nocturnal Hemoglobinuria.

BACKGROUND: Eculizumab, a humanized monoclonal antibody against complement protein C5 that inhibits terminal complement activation, has been shown to prevent complications of paroxysmal nocturnal hemoglobinuria (PNH) and improve quality of life and overall survival, but data on the use of eculizumab in women during pregnancy are scarce. METHODS: We designed a questionnaire to solicit data on pregnancies in women with PNH and sent it to the members of the International PNH Interest Group and to the physicians participating in the International PNH Registry. We assessed the safety and efficacy of eculizumab in pregnant patients with PNH by examining the birth and developmental records of the children born and adverse events in the mothers. RESULTS: Of the 94 questionnaires that were sent out, 75 were returned, representing a response rate of 80%. Data on 75 pregnancies in 61 women with PNH were evaluated. There were no maternal deaths and three fetal deaths (4%). Six miscarriages (8%) occurred during the first trimester. Requirements for transfusion of red cells increased during pregnancy, from a mean of 0.14 units per month in the 6 months before pregnancy to 0.92 units per month during pregnancy. Platelet transfusions were given in 16 pregnancies. In 54% of pregnancies that progressed past the first trimester, the dose or the frequency of use of eculizumab had to be increased. Low-molecular-weight heparin was used in 88% of the pregnancies. Ten hemorrhagic events and 2 thrombotic events were documented; both thrombotic events occurred during the postpartum period. A total of 22 births (29%) were premature. Twenty cord-blood samples were examined for the presence of eculizumab; the drug was detected in 7 of the samples. A total of 25 babies were breast-fed, and in 10 of these cases, breast milk was examined for the presence of eculizumab; the drug was not detected in any of the 10 breast-milk samples. CONCLUSIONS: Eculizumab provided benefit for women with PNH during pregnancy, as evidenced by a high rate of fetal survival and a low rate of maternal complications. (ClinicalTrials.gov number, NCT01374360.).

How we treat thrombotic thrombocytopenic purpura: Results of a Canadian TTP practice survey.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is a rare disease with 90% mortality if untreated. Since the Canadian Apheresis Group (CAG) trial showed greater survival with therapeutic plasma exchange (TPE) versus plasma infusion, there has been widespread adoption of TPE. Beyond TPE, there is significant practice variation. To characterize this, we developed a survey sent to physicians who might be directly involved in TTP management. METHODS: The survey was sent to CAG members as well as hematologists and nephrologists nationwide and addressed areas of controversy or recognized practice heterogeneity. Descriptive statistics were used to summarize responses, and the χ2 test was used to compare respondents who were and were not CAG physicians. We also compared responses by estimated frequency of TTP cases per year. RESULTS: The CAG response rate was 31% (13 of 42). The survey was sent to 665 non-CAG physicians, of whom 41 responded (6.1%). Though not statistically different, CAG and non-CAG respondents varied regarding use of corticosteroids, aspirin, and venous thromboembolism (VTE) prophylaxis. Significant differences were found between CAG and non-CAG groups regarding cryosupernatant as fluid choice (69.2% vs. 22.5%, P = .004) and the use of TPE tapering (84.6% vs. 51.3%, P = .034), respectively. CONCLUSION: TTP treatment is variable across centres in Canada. Areas of significant variation include the choice of replacement fluid for TPE and whether or not and how to taper TPE. Our survey highlights the practice heterogeneity that exists and identifies areas where more evidence is needed and perhaps where trials should be performed.