The incidence and prevalence of patients with paroxysmal nocturnal haemoglobinuria and aplastic anaemia PNH syndrome: A retrospective analysis of the UK's population-based haematological malignancy research network 2004-2018

Peptide-based therapeutics targeting genetic disorders

Genetic disorders (GDs) are challenging to treat owing to a lack of optimal treatment regimens and intricate and often difficult-to-understand underlying biological processes. Limited therapeutic approaches, which mostly provide symptomatic relief, are available. To date, a limited number of peptide-based drugs for the treatment of GDs are available, and several candidates are under clinical study. This review provides mechanistic insights into GDs and potential target areas where peptide-based drugs are beneficial. In addition, it emphasizes the usefulness of peptides as carriers for gene delivery, biomarkers for mutation detection and peptide-based vaccines for treating GDs.

A machine learning algorithm for the detection of paroxysmal nocturnal haemoglobinuria (PNH) in UK primary care electronic health records

BACKGROUND

Paroxysmal Nocturnal Haemoglobinuria (PNH) is an ultra-rare, acquired disorder that is challenging to diagnose due to varied symptoms, heterogeneous patient presentations, and lack of awareness among healthcare professionals. This leads to frequent misdiagnosis and delays in diagnosis. This study evaluated the feasibility of a machine learning model to identify undiagnosed PNH patients using structured electronic health records.

METHODS

The study used data from the Optimum Patient Care Research Database, which contains electronic health records from general practitioner (GP) practices across the United Kingdom. PNH patients were identified by the presence, and control patients by the absence of a PNH diagnosis code in their records. Clinical features (symptoms, diagnoses, healthcare utilisation) from 131 patients in the PNH group and 593,838 patients in the control group, were inputted to a tree-based XGBoost machine learning model to classify patients as either "positive" or "negative" for PNH suspicion. The algorithm was finalised after additional exclusions and inclusions applied. Performance was assessed using positive predictive value (PPV), recall and specificity. As the sample used to develop the algorithm was not representative of the true population prevalence, PPV was additionally adjusted to reflect performance in the wider population.

RESULTS

Of all the patients in the PNH group, 27% were classified as positive (recall). 99.99% of the control group were classified as negative (specificity). Of all the patients classified as positive, 60.4% had a diagnosis of PNH in their record (PPV). The PPV adjusted for the population prevalence of PNH was 19.59 suggesting nearly 1 in 5 patients flagged may warrant further PNH investigation. The key clinical features in the model were aplastic anaemia, pancytopenia, haemolytic anaemia, myelodysplastic syndrome, and Budd-Chiari syndrome.

CONCLUSION

This is the first study to combine clinical understanding of PNH with machine learning, demonstrating the ability to discriminate between PNH and control patients in retrospective electronic health records. With further investigation and validation, this algorithm could be deployed on live health data, potentially leading to earlier diagnosis for patients who currently experience long diagnostic delays or remain undiagnosed.

Paroxysmal Nocturnal Hemoglobinuria, Pathophysiology, Diagnostics, and Treatment

Background

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by intravascular hemolysis (IVH) due to diminished or absent inhibition of the complement system because of deficient expression of cell-anchored complement regulating surface proteins. IVH leads to heterogeneous symptoms such as anemia, abdominal pain, dyspnea, fatigue and increased rates of thrombophilia. Inhibitors of the terminal Complement cascade can reverse IVH leading to a significant reduction of disease burden such as thrombembolic events and also mortality.

Summary

Therapeutic inhibitors of the terminal complement cascade such as eculizumab or ravulizumab significantly improve overall survival through IVH-inhibition. However, not all patients experience complete disease control with normalization of hemoglobin levels and absolute reticulocyte counts (ARC) under terminal complement inhibition as a significant part of patients develop extravascular hemolysis (EVH). EVH can be clinically relevant causing persistent anemia and fatigue. New proximal complement inhibitors (CI) mainly targeting complement component C3 or factors of the amplification pathway such as pegcetacoplan, danicopan, and iptacopan became available and are meanwhile approved for marketing. Additional complement-inhibiting strategies are under clinical development. A switch from terminal to proximal CI in patients with significant EVH can achieve hemoglobin and ARC normalization and significant improvement in quality of life (QoL). Additional approvals of proximal CI agents for the treatment of hemolytic PNH in the first line are available for pegcetacoplan and iptacopan. So far, no evidence-based algorithm is available for decision-making in first-line treatment of which type of drug should be used for individual patients.

Key Messages

Terminal CIs in hemolytic PNH patients can block IVH and have led to a dramatically improved survival. Proximal CIs ameliorate anemia and improve QoL in patients with relevant EVH. However, more (real-world) data are needed to demonstrate long-term improvement in all patients with hemolytic PNH, especially those under first-line treatment with proximal CI.

Epidemiological estimates of paroxysmal nocturnal hemoglobinuria in Bulgaria

Paroxysmal nocturnal hemoglobinuria is a rare clonal hematopoietic stem cell disorder with debilitating health consequences if untreated. Although cases have been described globally, precise epidemiological distribution is difficult to assess due to geographical underrepresentation in disease reporting. Evaluation of the burden of paroxysmal nocturnal hemoglobinuria in Bulgaria is currently missing. To provide epidemiological estimates, a systematic literature search for publications in the Bulgarian language or by Bulgarian authors was performed for a ten-year period (2013-2022), and clinically relevant information on case presentation was collected. Additionally, data was retrieved from the National Health Insurance Fund and National Statistical Institute on the count of registered cases with ICD-10 code "D59.5" and census for the same period. The estimated prevalence of paroxysmal nocturnal hemoglobinuria is relatively lower in the Bulgarian population than in other countries, and it is estimated to be 2.77 cases per 1,000,000 patient years. The treatment pattern mainly shows conventional blood product support use and is consistent with the pre-complement inhibition era. Underdiagnosis, lack of a reliable disease reporting system, and, until recently, restricted access to complement inhibitor therapy are significant impediments to the management of paroxysmal nocturnal hemoglobinuria in Bulgaria.

Navigating the Complement Pathway to Optimize PNH Treatment with Pegcetacoplan and Other Currently Approved Complement Inhibitors

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare and potentially life-threatening hematologic disorder caused by a somatic mutation in a relevant portion of hematopoietic stem cells. Mutation of the phosphatidylinositol glycan biosynthesis class A (PIGA) gene prevents the expression of cell-surface proteins, including the complement regulatory proteins CD55 and CD59. With decreased or a lack of CD55 and CD59 expression on their membranes, PNH red blood cells become susceptible to complement-mediated hemolysis (symptoms of which include anemia, dysphagia, abdominal pain, and fatigue), leading to thrombosis. State-of-the-art PNH treatments act by inhibiting the dysregulated complement at distinct points in the activation pathway: late at the C5 level (C5 inhibitors, eculizumab, ravulizumab, and crovalimab), centrally at the C3 level (C3/C3b inhibitors and pegcetacoplan), and early at the initiation and amplification of the alternative pathway (factor B inhibitor, iptacopan; factor D inhibitor, danicopan). Through their differing mechanisms of action, these treatments elicit varying profiles of disease control and offer valuable insights into the molecular underpinnings of PNH. This narrative review provides an overview of the mechanisms of action of the six complement inhibitors currently approved for PNH, with a focus on the C3/C3b-targeted therapy, pegcetacoplan.

Patient-reported outcomes and daily activity assessed with a digital wearable device in patients with paroxysmal nocturnal hemoglobinuria treated with ravulizumab: REVEAL, a prospective, observational study

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, chronic blood disorder. Symptoms such as fatigue can have a substantial impact on patients' physical activity levels, sleep, quality of life, and work productivity. Ravulizumab treatment can reduce thrombosis risk, improve survival and quality of life, and reduce fatigue in PNH, but information is limited on how it impacts sleep and physical activity. Here, data on resting heart rate, daily physical activity, and sleep in ravulizumab-treated patients with PNH were passively collected via a digital wearable activity-tracking device and patient-reported outcome (PRO) data were collected via weekly surveys in the same cohort.

METHODS

REVEAL was a 32-week prospective observational cohort study in individuals with PNH receiving ravulizumab in the USA. A wrist-worn Fitbit™ collected data on resting heart rate, daily step count, and sleep duration from eligible patients. Patients also completed the following electronic weekly surveys: Functional Assessment of Chronic Illness Therapy (FACIT) - Fatigue, Patient-Reported Outcomes Measurement Information System (PROMIS) Global Physical Health, PROMIS Global Mental Health, PROMIS Sleep-Related Impairment and Sleep Disturbance, and Work Productivity and Activity Impairment Questionnaire - Specific Health Problem (WPAI-SHP). Data collected from the activity trackers and surveys were compared against US general population values reported in the literature.

RESULTS

Twenty-eight ravulizumab-treated patients were included (median age: 34 years; 54% female). PRO scores were within US general population normative values, including FACIT-Fatigue (40.0), PROMIS Global Physical Health (51.0), Global Mental Health (51.0), Sleep-Related Impairment (50.0), and Sleep Disturbance (49.0). Similarly, mean resting heart rate (67 bpm), daily step count (7476), and sleep duration (7.7 h) were within the range of US general population values. Daily step count was positively correlated with PROMIS Global Physical and Mental Health scores.

CONCLUSIONS

This was the first study to use digital monitoring technology to collect data on physical activity and sleep in patients with PNH. The findings indicate that ravulizumab treatment enables patients with PNH to achieve activity levels (heart rate, sleep duration, step count) and quality of life that are comparable to those of the US general population. A weak positive correlation was identified between patient-reported physical and mental health and daily physical activity levels.

Diagnostic landscape of first-time cytometric screening for paroxysmal nocturnal hemoglobinuria in Poland in 2013-2022

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by PIG-A mutations, leading to glycophosphatidylinositol (GPI)-anchored proteins deficiency that triggers hemolysis - a hallmark of the disease. PNH diagnostics is based on high-sensitivity multicolor flow cytometry (MFC), enabling to detect even small populations of PNH cells. In this single-center, retrospective study, we aimed to characterize a cohort of PNH clone-positive patients first time screened from January 1st, 2013 until December 31st, 2022 with MFC according to International Clinical Cytometry Society PNH Consensus Guidelines.

RESULTS

Out of 2790 first-time screened individuals, the presence of PNH clone in neutrophils was detected in 322 patients, including 49 children and 273 adults. Annual incidence was stable at a median of 31 patients (14 and 19 with clone sizes ≤ 1% and > 1%, respectively), with a decline in number of patients with clone sizes > 1% observed in 2020, potentially influenced by the COVID-19 pandemic. The most common screening indications were aplastic anemia and other cytopenias.

CONCLUSIONS

A significant underrepresentation of hemolytic patients was observed as compared to the published cohorts suggesting that these patients are missed in diagnostic process and classic PNH remains underdiagnosed in Poland.

Eculizumab for paroxysmal nocturnal hemoglobinuria: Two cases of successful pregnancy outcomes

Paroxysmal nocturnal hemoglobinuria is a rare disease with the incidence ranging from 0.08 to 0.57 per 100,000 person-years. Up to 25% of cases in women are detected during pregnancy. We report two cases of successful pregnancy outcomes in patients treated with eculizumab, pointing out the importance of interdisciplinary approach in these high-risk pregnancies.

Pegcetacoplan in paroxysmal nocturnal haemoglobinuria: Its use, its clinical effectiveness, and its influence on health-related quality of life and productivity

OBJECTIVES

To describe real-world use/effectiveness of pegcetacoplan (PEG) in paroxysmal nocturnal haemoglobinuria (PNH).

METHODS

Data were drawn from the Adelphi PNH Disease Specific Programme™, a cross-sectional survey conducted in France, Italy, Germany, Spain and the United States from January to November 2022. Patients had a confirmed PNH diagnosis and received PEG for ≥1 month. Physicians reported patient characteristics, treatment use/satisfaction and their perception of patients' fatigue and health-related quality of life (HRQoL). Patients reported treatment satisfaction and completed questionnaires assessing fatigue, HRQoL and productivity. Descriptive statistics were reported.

RESULTS

Overall, 14 physicians provided data for 61 patients who had received 1080 mg/dose PEG for 1.3-14.8 months. At data collection compared to PEG initiation: haemoglobin was 2.5 g/dL higher on average; proportion of patients with lactate dehydrogenase (LDH) ≥1.5 × upper limit of normal was reduced by 27.4%; physician-perceived fatigue was lower and HRQoL better. Physician- and patient-reported treatment satisfaction was high for >90% of patients. Physicians and patients were more satisfied with PEG than previously prescribed C5 complement inhibitors. Mean work impairment and activity impairment in the 7 days prior to data collection were 32.9% and 22.4%, respectively.

CONCLUSIONS

These real-world data support the effectiveness of PEG through positive effects on haemoglobin, LDH, fatigue and HRQoL.

Biomimetic proteolipid vesicles for reverting GPI deficiency in paroxysmal nocturnal hemoglobinuria

Nano-vesicular carriers are promising tissue-specific drug delivery platforms. Here, biomimetic proteolipid vesicles (BPLVs) were used for delivery of glycosylphosphatidylinositol (GPI)-anchored proteins to GPI deficient paroxysmal nocturnal hemoglobinuria (PNH) cells. BPLVs were assembled as single unilamellar monodispersed (polydispersity index, 0.1) negatively charged (ζ-potential, -28.6 ± 5.6 mV) system using microfluidic technique equipped with Y-shaped chip. GPI-anchored and not-GPI proteins on BPLV surface were detected by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from healthy and PNH subjects were treated with BPLVs (final concentration, 0.5 mg/mL), and cells displayed an excellent protein uptake, documented by flow cytometry immunophenotyping and confocal microscopy. BPLV-treated cells stressed with complement components showed an increased resistance to complement-mediated lysis, both healthy and PNH PBMCs. In conclusion, BPLVs could be effective nanocarriers for protein transfer to targeted cells to revert protein deficiency, like in PNH disease. However, further in vivo studies are required to validate our preclinical in vitro results.

The disease burden of paroxysmal nocturnal hemoglobinuria in Denmark: Epidemiology, survival, healthcare resource utilization, costs, treatment gaps, and labor market attachment

OBJECTIVES

To establish epidemiology, healthcare costs, and labor market attachment in patients with paroxysmal nocturnal hemoglobinuria (Pt-PNH) in Denmark.

METHODS

Data were from Statistics Denmark and the Danish Health Data Authority national population registers (2005-2021). Descriptive baseline statistics characterized the Pt-PNH analytic population; ordinary least squares and adjusted Cox proportional hazards regressions measured outcomes in the Pt-PNH versus Danish general population matched comparators.

RESULTS

Overall PNH incidence in Denmark was n = 11 during 2007-2009, n = 25 during 2016-2018 and n = 7 during 2019-2020; prevalence increased from n = 13 in 2006 to n = 62 in 2021. Of the overall n = 85 Pt-PNH; n = 24 were treated with complement-5 inhibitors (Pt-C5i) and n = 61 not treated with C5i (Pt-nC5i). Versus respective comparators, all patients had significantly greater annual per-patient costs (from inpatient hospital admissions, outpatient contacts, PNH treatments; indirect costs from lost earnings + transfer payments; post-diagnosis for Pt-PNH and Pt-nC5i, post-treatment initiation for Pt-C5i). The Pt-C5i incurred the greatest healthcare and indirect cost differences (€709 119; €152 832, respectively) followed by the Pt-PNH (€189 323; €29 159, respectively) and Pt-nC5i (€95 548; €4713, respectively). The Pt-PNH versus comparators also had an increased hazard of death (2.71 [95% CI, 1.63 - 4.51]).

CONCLUSION

Although a rare disease, PNH is associated with significant patient, healthcare system, and societal burdens in Denmark.

Advancing Subcutaneous Dosing Regimens for Biotherapeutics: Clinical Strategies for Expedited Market Access

In recent years, subcutaneous administration of biotherapeutics has made significant progress. The self-administration market for rheumatoid arthritis has witnessed the introduction of additional follow-on biologics, while the first subcutaneous dosing options for monoclonal antibodies have become available for multiple sclerosis. Oncology has also seen advancements with the authorization of high-volume subcutaneous formulations, facilitated by the development of high-concentration formulations and innovative delivery systems. Regulatory and Health Technology Assessment bodies increasingly consider preference data in filing dossiers, particularly in evaluating novel drug delivery methods. The adoption of a pharmacokinetic-based clinical bridging approach has become standard for transitioning from intravenous to subcutaneous administration. Non-inferiority studies with pharmacokinetics as the only primary endpoint have started deviating from traditional randomization schemes, favoring the subcutaneous route and comparing with historical intravenous data. While nonclinical and computational models made progress in predicting safety and immunogenicity for subcutaneously dosed antibodies, clinical trial evidence remains essential due to inter-individual variations and the impact of formulation parameters on anti-drug antibody formation. Ongoing technological advancements and the expanding knowledge base on pharmacokinetic-pharmacodynamic correlation across specialty areas are expected to further accelerate clinical development of subcutaneous biologics.

Addition of danicopan to ravulizumab or eculizumab in patients with paroxysmal nocturnal haemoglobinuria and clinically significant extravascular haemolysis (ALPHA): a double-blind, randomised, phase 3 trial

BACKGROUND

Symptoms of anaemia due to clinically significant extravascular haemolysis can affect patients with paroxysmal nocturnal haemoglobinuria (PNH) treated with C5 inhibitors (ravulizumab or eculizumab). The aim of this study was to assess the efficacy and safety of danicopan (ALXN2040), an investigational, first-in-class, oral complement factor D inhibitor, as add-on therapy to ravulizumab or eculizumab in patients with PNH and clinically significant extravascular haemolysis.

METHODS

ALPHA is an ongoing, international, phase 3, randomised, double-blind, placebo-controlled trial evaluating danicopan as add-on therapy to ravulizumab or eculizumab. Eligible patients were adults (age ≥18 years) with PNH and clinically significant extravascular haemolysis (haemoglobin ≤9·5 g/dL; absolute reticulocyte count ≥120 × 109/L) on ravulizumab or eculizumab for at least 6 months. Patients were randomly assigned (2:1) to danicopan or placebo added to ravulizumab or eculizumab for 12 weeks using an interactive response technology system. Randomisation was stratified based on transfusion history, haemoglobin, and patients enrolled from Japan. The initial oral danicopan dose was 150 mg three times a day; escalation to 200 mg three times a day was permitted based on clinical response. The infusion dose level of eculizumab (every 2 weeks) ranged from 900 mg to 1500 mg, and for ravulizumab (monthly or every 8 weeks) ranged from 3000 mg to 3600 mg. The primary endpoint was change in haemoglobin concentration from baseline to week 12. Here we present the protocol-prespecified interim analysis, planned when approximately 75% of participants were randomly assigned to treatment and completed or discontinued at 12 weeks. This trial is registered with ClinicalTrials.gov (NCT04469465).

FINDINGS

Individuals were randomly assigned between Dec 16, 2020, and Aug 29, 2022. At data cutoff (June 28, 2022), 73 individuals were randomly assigned, received treatment, and were analysed for safety (danicopan, n=49; placebo, n=24). The protocol-prespecified interim efficacy analysis set included the first 63 participants (danicopan, n=42; placebo, n=21). At week 12, danicopan plus ravulizumab or eculizumab increased haemoglobin versus placebo plus ravulizumab or eculizumab (least squares mean [LSM] change from baseline: danicopan, 2·94 g/dL [95% CI 2·52 to 3·36]; placebo, 0·50 g/dL [-0·13 to 1·12]; LSM difference, 2·44 g/dL [1·69 to 3·20]; p<0·0001). Grade 3 adverse events in the danicopan group were increased alanine aminotransferase (two [4%] of 49 patients), leukopenia (one [2%]), neutropenia (two [4%]), cholecystitis (one [2%]), COVID-19 (one [2%]), increased aspartate aminotransferase (one [2%]), and increased blood pressure (one [2%]), and in the placebo group were anaemia (one [4%] of 24 patients), thrombocytopenia (one [4%]), and asthenia (one [4%]). The serious adverse events reported in the danicopan group were cholecystitis (one [2%] patient) and COVID-19 (one [2%]) and in the placebo group were anaemia and abdominal pain, both in one (4%) patient. There were no serious adverse events related to study drug or deaths reported in the study.

INTERPRETATION

These primary efficacy and safety results show that danicopan as add-on treatment to ravulizumab or eculizumab significantly improved haemoglobin concentrations at week 12 with no new safety concerns, suggesting an improved benefit-risk profile in patients with PNH and clinically significant extravascular haemolysis.

FUNDING

Alexion, AstraZeneca Rare Disease.

Early Mortality in Paroxysmal Nocturnal Hemoglobinuria

OBJECTIVES

 The elevated mortality risk among patients with paroxysmal nocturnal hemoglobinuria (PNH) has been suggested to derive from a high risk of thromboembolism (TE); however, the risks of coexisting cardiovascular risk factors are not well described. We studied mortality associated with PNH taking comorbidity and treatment into account.

METHODS

Patients with PNH (n=115) were identified in the 1977-2016 Danish National Patient Register (DNPR). For each patient with PNH, we identified 50 age- and sex-matched general population comparators. Using the Kaplan-Meier estimator and Cox regression, we compared the overall survival of patients with comparators. Cumulative incidences were used to analyze the effects of comorbidity and the causes of death.

RESULTS

One-year survival among patients and comparators was 92.2% and 99.4%, and after 10 years, it was 68.4% and 85.8%, respectively. Early mortality was associated with older age, higher levels of comorbidity, and solid malignancies prior to PNH diagnosis. The leading causes of death were infections and associated hematological diseases. Patients with early mortality were less likely to have received treatment with eculizumab and/or warfarin. Cardiovascular risk factors were evenly distributed between patients and comparators at diagnosis.

CONCLUSION

We conclude that early mortality in PNH is associated with older age, cardiovascular comorbidity, and hematological malignancies.

The cost-effectiveness of pegcetacoplan in complement treatment-naïve adults with paroxysmal nocturnal hemoglobinuria in the USA

Aim: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by hemolytic anemia, bone marrow failure and thrombosis, and is associated with high healthcare burden. We evaluated the cost-effectiveness of pegcetacoplan, a proximal complement-3 inhibitor (C3i), compared with the C5i, eculizumab and ravulizumab, in complement treatment-naive adults with PNH, from the US healthcare payer perspective. Materials & methods: A de novo cost-effectiveness model based on a Markov cohort structure evaluated lifetime (55-year) PNH costs and outcomes. The 6-month cycles of the model reflected the follow-up period of PRINCE (NCT04085601), an open-label trial of pegcetacoplan compared with eculizumab in C5i-naive patients. Data from PRINCE informed the clinical, safety and health-related quality of life outcomes in the model. Results: Pegcetacoplan was associated with lifetime cost savings of USD1,176,808 and USD213,062 relative to eculizumab and ravulizumab, respectively (largely attributed to reduced drug costs and blood transfusions), and additional quality-adjusted life years (QALYs) of 0.25 and 0.24. Conclusion: In patients with PNH who are treatment-naive, the base-case cost-effectiveness analysis, scenario analysis and sensitivity analysis showed both lifetime cost savings and increased QALYs associated with pegcetacoplan compared with eculizumab or ravulizumab in the USA.

Relationship of paroxysmal nocturnal hemoglobinuria (PNH) granulocyte clone size to disease burden and risk of major vascular events in untreated patients: results from the International PNH Registry

Paroxysmal nocturnal hemoglobinuria (PNH) is caused by acquired gene mutations resulting in deficiency of glycosylphosphatidylinositol (GPI)-anchored complement regulatory proteins on the surface of blood cells, leading to terminal complement-mediated intravascular hemolysis and increased risk of major adverse vascular events (MAVEs). Using data from the International PNH Registry, this study investigated the relationship between the proportion of GPI-deficient granulocytes at PNH onset and (1) the risk for MAVEs (including thrombotic events [TEs]) and (2) the following parameters at last follow-up: high disease activity (HDA); lactate dehydrogenase (LDH) ratio; fatigue; abdominal pain; and rates of overall MAVEs and TEs. A total of 2813 patients untreated at enrollment were included and stratified by clone size at PNH disease onset (baseline). At last follow-up, higher proportion of GPI-deficient granulocytes (≤ 5% vs. > 30% clone size) at baseline was associated with significantly increased HDA incidence (14% vs. 77%), mean LDH ratio (1.3 vs. 4.7 × upper limit of normal), and rates of MAVEs 1.5 vs. 2.9 per 100 person-years) and TEs (0.9 vs. 2.0 per 100 person-years). Fatigue was evident in 71 to 76% of patients regardless of clone size. Abdominal pain was more frequently reported with clone size > 30%. A larger clone size at baseline appears to indicate a greater disease burden and risk of TEs and MAVEs and may inform decision making among physicians managing PNH patients at risk of experiencing TEs or other MAVEs. ClinicalTrials.gov ID: NCT01374360.

Nationwide study of eculizumab in paroxysmal nocturnal hemoglobinuria: Evaluation of treatment indications and outcomes

Eculizumab is an effective treatment for paroxysmal nocturnal hemoglobinuria (PNH). However, considering the risk of life-threatening meningococcal disease, life-long duration and costs, there are strict criteria for initiation of therapy. To evaluate the application and real-world effectiveness of eculizumab in the Netherlands, a multicenter retrospective cohort study was conducted: indications and treatment outcomes were collected for 105 Dutch PNH patients. In all patients, eculizumab was initiated conforming to indications as formulated in the Dutch PNH guideline. According to recently published response criteria, 23.4% of the patients had reached a complete hematological response, 53.2% a good or partial response, and 23.4% a minor response after 12 months of therapy. In the majority of patients the response remained stable during long-term follow-up. The degree and relevance of extravascular hemolysis significantly differed between response groups (p = 0.002). Improvements of EORTC-QLQc30 and FACIT-fatigue scores were observed, however patients reported lower scores than the general population. A detailed evaluation of 18 pregnancies during eculizumab showed no maternal or fetal deaths, and no thromboembolic events during pregnancy. This study demonstrates that the majority of patients benefit from eculizumab when adhering to the indications as formulated in the Dutch PNH guideline. However, novel therapies are needed to further improve real-world outcomes, such as hematological responses and quality of life.

Paroxysmal nocturnal hemoglobinuria: Where we stand

For the last 20 years, therapy of paroxysmal nocturnal hemoglobinuria (PNH) relied-up until recently-on antibody based terminal complement inhibitionon. PNH pathophysiology-a mutational defect leading to partial or complete absence of complement-regulatory proteins on blood cells-leads to intravascular hemolysis and consequences such as thrombosis and other sequelae. A plethora of new drugs interfering with the proximal and terminal complement cascade are under recent development and the first "proof-of-pinciple" proximal complement inhibitor targeting C3 has been approved in 2021. "PNH: where we stand" will try to give a brief account on where we came from and where we stand focusing on approved therapeutic options. The associated improvements as well as potential consequences of actual and future treatments as well as their impact on the disease will continue to necessitate academic and scientific focus on improving treatment options as well as on side effects and outcomes relevant to individual patient lives and circumstances in order to develop effective, safe, and available treatment for all hemolytic PNH patients globally.

Paroxysmal nocturnal hemoglobinuria: A rare case of recurrent episodes of icterus

In this work we describe a rare case of a patient with paroxysmal nocturnal hemoglobinuria (PNH) developed on the background of specific medical history of morbus Gilbert with chronically elevated bilirubin and recurrent attacks of macroscopic haematuria. We focus on a differential diagnosis of the disease, its obstacles, and treatment options.

Pancytopenia in a Case of Aplastic Anaemia/Paroxysmal Nocturnal Haemoglobinuria Unmasked by SARS-CoV-2 Infection: A Case Report

During an acute SARS-CoV-2 infection, a diagnosis of Aplastic Anaemia associated with Paroxysmal Nocturnal Haemoglobinuria (AA/PNH) was made in a 78-year-old woman who had presented to the emergency department with severe pancytopenia. It is possible that she had subclinical AA/PNH that was unmasked during the acute COVID-19 infection, but we can also suspect a direct role of the virus in the pathogenesis of the disease, or we can hypothesize that COVID-19 infection changed the phosphatidylinositol glycan class A (PIGA) gene pathway.

The importance of terminal complement inhibition in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, chronic hematologic disorder associated with inappropriate terminal complement activity on blood cells that can result in intravascular hemolysis (IVH), thromboembolic events (TEs), and organ damage. Untreated individuals with PNH have an increased risk of morbidity and mortality. Patients with PNH experiencing IVH often present with an elevated lactate dehydrogenase (LDH; ⩾ 1.5 × the upper limit of normal) level which is associated with a significantly higher risk of TEs, one of the leading causes of death in PNH. LDH is therefore used as a biomarker for IVH in PNH. The main objective of PNH treatment should therefore be prevention of morbidity and mortality due to terminal complement activation, with the aim of improving patient outcomes. Approval of the first terminal complement inhibitor, eculizumab, greatly changed the treatment landscape of PNH by giving patients an effective therapy and demonstrated the critical role of terminal complement and the possibility of modulating it therapeutically. The current mainstays of treatment for PNH are the terminal complement component 5 (C5) inhibitors, eculizumab and ravulizumab, which have shown efficacy in controlling terminal complement-mediated IVH, reducing TEs and organ damage, and improving health-related quality of life in patients with PNH since their approval by the United States Food and Drug Administration in 2007 and 2018, respectively. Moreover, the use of eculizumab has been shown to reduce mortality due to PNH. More recently, interest has arisen in developing additional complement inhibitors with different modes of administration and therapeutics targeting other components of the complement cascade. This review focuses on the pathophysiology of clinical complications in PNH and explores why sustained inhibition of terminal complement activity through the use of complement inhibitors is essential for the management of patients with this chronic and debilitating disease.

The Role of T Lymphocytes in the Pathogenesis of Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell genetic mutation disease that causes defective erythrocyte membrane hemolysis. Its pathologic basis is the mutation of the PIG-A gene, whose product is necessary for the synthesis of glycosylphosphatidylinositol (GPI) anchors; the mutation of PIG-A gene results in the reduction or deletion of the GPI anchor, which leads to the deficiency of GPI-anchored proteins (GPI-APs), such as CD55 and CD59, which are complement inhibitors. The deficiency of complement inhibitors causes chronic complement-mediated intravascular hemolysis of GPI-anchor-deficient erythrocyte. PIG-A gene mutation could also be found in bone marrow hematopoietic stem cells (HSCs) of healthy people, but they have no growth advantage; only the HSCs with PIG-A gene mutation in PNH patients have this advantage and expand. Besides, HSCs from PIG-A-knockout mice do not show clonal expansion in bone marrow, so PIG-A mutation cannot explain the clonal advantage of the PNH clone and some additional factors are needed; thus, in recent years, many scholars have put forward the theories of the second hit, and immune escape theory is one of them. In this paper, we focus on how T lymphocytes are involved in immune escape hypothesis in the pathogenesis of PNH.

Immune Phenomena in Myeloid Neoplasms: An "Egg or Chicken" Question

Immune phenomena are increasingly reported in myeloid neoplasms, and include autoimmune cytopenias/diseases and immunodeficiency, either preceding or complicating acute myeloid leukemia, myelodysplastic syndromes (MDS), chronic myeloproliferative neoplasms, and bone marrow failure (BMF) syndromes. Autoimmunity and immunodeficiency are the two faces of a dysregulated immune tolerance and surveillance and may result, along with contributing environmental and genetic factors, in an increased incidence of both tumors and infections. The latter may fuel both autoimmunity and immune activation, triggering a vicious circle among infections, tumors and autoimmune phenomena. Additionally, alterations of the microbiota and of mesenchymal stem cells (MSCs) pinpoint to the importance of a permissive or hostile microenvironment for tumor growth. Finally, several therapies of myeloid neoplasms are aimed at increasing host immunity against the tumor, but at the price of increased autoimmune phenomena. In this review we will examine the epidemiological association of myeloid neoplasms with autoimmune diseases and immunodeficiencies, and the pivotal role of autoimmunity in the pathogenesis of MDS and BMF syndromes, including the paroxysmal nocturnal hemoglobinuria conundrum. Furthermore, we will briefly examine autoimmune complications following therapy of myeloid neoplasms, as well as the role of MSCs and microbiota in these settings.