Laboratory studies for paroxysmal nocturnal hemoglobinuria, with emphasis on flow cytometry

The Features of COVID-19's Course and the Efficacy of the Gam-COVID-Vac Vaccine in Patients with Paroxysmal Nocturnal Hemoglobinuria

COVID-19 and other infectious diseases can exacerbate the course of paroxysmal nocturnal hemoglobinuria (PNH). The efficacy and safety of the Gam-COVID-Vac vaccine in patients with PNH has not been adequately studied. A retrospective, observational, cohort, non-comparative study was performed to assess the course of COVID-19 as well as the safety and efficacy of the Gam-COVID-Vac (Sputnik V) vaccine in patients with paroxysmal nocturnal hemoglobinuria (PNH). The study included data from 52 patients with PNH aged 18 to 75 years, 38 of whom received background therapy with eculizumab (Elizaria®) between March 2020 and January 2022. COVID-19 was diagnosed according to the results of PCR testing. The patients were divided into two groups for comparison of the incidence of COVID-19. Group 1 included non-vaccinated patients with PNH, and Group 2 included patients vaccinated prior to the onset of COVID-19. According to vaccination, patients were subdivided into non-vaccinated and vaccinated groups without signs of previous COVID-19 at the beginning of the analyzed period, and patients vaccinated half a year or more after recovery from COVID-19. Testing for anti-SARS-CoV-2 IgG levels was carried out in patients with PNH in the year after their COVID-19. Tests for anti-SARS-CoV-2 RBD IgG levels were performed on vaccinated patients. In total, 28 (53.8%) of the enrolled patients had COVID-19, including asymptomatic forms in 7 (25%) and mild forms in 16 (57%) patients. A total of 22 (42.3%) patients were fully vaccinated with Gam-COVID-Vac, of which 13 (25%) patients were vaccinated without the signs of previous SARS-CoV-2infection, and 9 (17.3%) patients were vaccinated after COVID-19. The number of patients who had COVID-19 was about two times higher in Group 1 (non-vaccinated; 24) (61.5%), whereas in Group 2 (vaccinated), the number of patients with COVID-19 was only 4 (30.8%). The proportion and number of patients who did not have COVID-19 was higher in the group of vaccinated patients (9; 69.2%) than in the group of non-vaccinated patients (15; 38.5%) (p = 0.054). In patients who had been infected with COVID-19, maximum concentrations of anti-SARS-CoV-2 IgG were observed 2-3 months after the acute infection phase, followed by a gradual decline by month 9-10. The mean RBD IgG concentration was higher in the group of patients who had been infected by COVID-19 than in the group of patients without COVID-19 (p = 0.047). Therapy type, including eculizumab, did not have a significant impact on RBD IgG titers (p > 0.05). Hospitalization was required in five (18%) patients, all of whom had breakthrough hemolysis and severe lung damage on CT scans. After the first dose, adverse events (AEs) were reported in 41% of the patients (body temperature increased in 18%; headache in 13.6%; and pain in joints in 4.5%; colitis exacerbation was observed in 4.5%). After the second dose, no AEs were reported. The performed study suggests the possible efficacy and demonstrates the safety of Gam-COVID-Vac (Sputnik V) for the prophylaxis of COVID-19 in patients with PNH who experience immunosuppression due to target therapy.

Complement Inhibitors in the Management of Complement-Mediated Hemolytic Uremic Syndrome and Paroxysmal Nocturnal Hemoglobinuria

BACKGROUND

Complement-mediated HUS (CM-HUS) and paroxysmal nocturnal hemoglobinuria (PNH) are rare hematologic disorders that cause dysregulation and hyperactivation of the complement system. Historically, treatment of CM-HUS involved plasma exchange (PLEX), often with limited benefit and variable tolerance. Conversely, PNH was treated with supportive care or hemopoietic stem cell transplant. Within the last decade, monoclonal antibody therapies that block terminal complement pathway activation, have emerged as less invasive and more efficacious options for management of both disorders. This manuscript seeks to discuss a relevant clinical case of CM-HUS and the evolving landscape of complement inhibitor therapies for CM-HUS and PNH.

AREAS OF UNCERTAINTY

Eculizumab, the first humanized anti-C5 monoclonal antibody, has been the standard of care in treating CM-HUS and PNH for over a decade. Although eculizumab has remained an effective agent, the variability in ease and frequency of administration has remained an obstacle for patients. The development of novel complement inhibitor therapies with longer half-lives, has allowed for changes in frequency and route of administration, thus improving patient QOL. However, there are limited prospective clinical trial data given disease rarity, and limited information on variable infusion frequency and length of treatment.

THERAPEUTIC ADVANCES

Recently, there has been a push to formulate complement inhibitors that improve QOL while maintaining efficacy. Ravulizumab, a derivative of eculizumab, was developed to allow for less frequent administration, while remaining efficacious. In addition, the novel oral and subcutaneous therapies, danicopan and crovalimab, respectively, along with pegcetacoplan are currently undergoing active clinical trials, and poised to further reduce treatment burden.

CONCLUSION

Complement inhibitor therapies have changed the treatment landscape for CM-HUS and PNH. With a significant emphasis on patient QOL, novel therapies continue to emerge and require an in-depth review of their appropriate use and efficacy in these rare disorders.

CLINICAL CASE

A 47-year-old woman with hypertension and hyperlipidemia presented with shortness of breath and was found to have hypertensive emergency in the setting of acute renal failure. Her serum creatinine was 13.9 mg/dL; elevated from 1.43 mg/dL 2 years before. The differential diagnosis for her acute kidney injury (AKI) included infectious, autoimmune, and hematologic processes. Infectious work-up was negative. ADAMTS13 activity level was not low at 72.9%, ruling out thrombotic thrombocytopenic purpura (TTP). Patient underwent a renal biopsy, which revealed acute on chronic thrombotic microangiopathy (TMA). A trial of eculizumab was initiated with concurrent hemodialysis. The diagnosis of CM-HUS was later confirmed by a heterozygous mutation in complement factor I (CFI), resulting in increased membrane attack complex (MAC) cascade activation. The patient was maintained on biweekly eculizumab and was eventually transitioned to ravulizumab infusions as an outpatient. Her renal failure did not recover, and the patient remains on hemodialysis while awaiting kidney transplantation.

Immunophenotypic assessment of PNH clones in major and minor cell lineages in the peripheral blood of patients with paroxysmal nocturnal hemoglobinuria

BACKGROUND

Flow cytometric immunophenotyping is essential for the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH). Most cases have easy to interpret flow cytometry profiles with red cells, neutrophils and monocytes showing complete deficiency of glycophosphatidylinositol (GPI) linked antigen expression. Some cases are more challenging to interpret due to the presence of multiple populations of PNH cells and variable levels of GPI antigen expression.

METHODS

We studied 46 known PNH patients, many with complex immunophenotypic profiles using a novel, single tube, multi-parameter 7-color immunophenotyping assay that allowed simultaneous detection and assessment of PNH clones within multiple lineages of peripheral blood leucocytes. Red cell PNH clones were also assessed in total and immature (CD71+) components by CD59 expression.

RESULTS

For individual patients, total PNH clones in each cell lineage were highly correlated. Monocytes, eosinophils and basophils showed the highest proportions of PNH cells. Red cell PNH clones were typically smaller than monocyte and neutrophil PNH clones. In most cases, PNH clones were detectable in minor leucocyte populations where multiple populations of PNH cells were present, variability in the proportions of type II and type III cells was seen across different cell lineages, even though total PNH clones remained similar.

CONCLUSIONS

This study shows that PNH patients with multiple PNH clones do not always display the same abnormality across all cell lineages routinely tested. There is no simple explanation for this but is likely due to a combination of complex molecular, genetic and biochemical dysfunction in different blood cell types.

A Case of Paroxysmal Cold Hemoglobinuria Possessing Moderate Paroxysmal Nocturnal Hemoglobinuria-Type Erythrocytes

Patient: Female, 82-year-old

Final Diagnosis: Paroxysmal cold hemoglobinuria

Symptoms: Anemia

Medication:—

Clinical Procedure: —

Specialty: Hematology

Diagnostic work-up for severe aplastic anemia in children: Consensus of the North American Pediatric Aplastic Anemia Consortium

The North American Pediatric Aplastic Anemia Consortium (NAPAAC) is a group of pediatric hematologist-oncologists, hematopathologists, and bone marrow transplant physicians from 46 institutions in North America with interest and expertise in aplastic anemia, inherited bone marrow failure syndromes, and myelodysplastic syndromes. The NAPAAC Bone Marrow Failure Diagnosis and Care Guidelines Working Group was established with the charge of harmonizing the approach to the diagnostic workup of aplastic anemia in an effort to standardize best practices in the field. This document outlines the rationale for initial evaluations in pediatric patients presenting with signs and symptoms concerning for severe aplastic anemia.

Raman tweezers as an alternative diagnostic tool for paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease characterized by hemolysis of red blood cells (RBC) and venous thrombosis. The gold standard method for the diagnosis of this disease is flow cytometry. Here, we propose a combined optical tweezers and Raman spectral (Raman tweezers) approach to analyze blood samples from volunteers with or without PNH conditions. Raman spectroscopy is a well-known method for investigating a material's chemical structure and is also used in molecular analysis of biological compounds. In this study, we trap individual RBCs found in whole blood samples drawn from PNH patients and the control group. Evaluation of the Raman spectra of these cells by band component analysis and machine learning shows a significant difference between the two groups. The specificity and the sensitivity of the training performed by support vector machine (SVM) analysis were found to be 81.8% and 78.3%, respectively. This study shows that an immediate and high accuracy test result is possible for PNH disease by employing Raman tweezers and machine learning.

Mutations in PIGA cause a CD52-/GPI-anchor-deficient phenotype complicating alemtuzumab treatment in T-cell prolymphocytic leukemia

OBJECTIVE

Infusional alemtuzumab followed by consolidating allogeneic hematopoietic stem cell transplantation in eligible patients is considered a standard of care in T-cell prolymphocytic leukemia (T-PLL). Antibody selection against CD52 has been associated with the development of CD52-negative leukemic T cells at time of relapse. Clinical implications and molecular mechanisms underlying this phenotypic switch are unknown.

METHODS

We performed flow cytometry and real-time-PCR for CD52-expression and next generation sequencing for PIGA mutational analyses.

RESULTS

We identified loss of CD52 expression after alemtuzumab treatment in two of 21 T-PLL patients resulting from loss of GPI-anchor expression caused by inactivating mutations of the PIGA gene. One patient with relapsed T-PLL exhibited a single PIGA mutation, causing a CD52-negative escape variant of the initial leukemic cell clone, preventing alemtuzumab-retreatment. The second patient with continued complete remission after alemtuzumab treatment harbored three different PIGA mutations that affected either the non-neoplastic T cell or the mononuclear cell compartment and resulted in symptomatic paroxysmal nocturnal hemoglobinuria. Next generation sequencing of T-PLL cells collected before the initiation of treatment revealed PIGA wild-type sequence reads in all 16 patients with samples available for testing.

CONCLUSION

These data indicate that PIGA mutations were acquired during or after completion of alemtuzumab treatment.

Increasing Incidence and Prevalence of Acquired Hemolytic Anemias in Denmark, 1980-2016

Background

Acquired hemolytic disorders—autoimmune hemolytic anemia (AIHA), cold agglutinin disease (CAD), paroxysmal nocturnal hemoglobinuria (PNH), drug-induced hemolysis (DIHA), and acquired hemolysis not otherwise specified (AHNOS)—are considered rare. Despite their potentially major health implications, data regarding their incidence and prevalence are scarce.

Methods

To fill this gap we collected data regarding all patients with acquired hemolytic disorder diagnoses in 1977–2016 from the Danish National Patient Register. These data were linked with vital and migration status information from the Danish Civil Registration System. From these data combined with annual demographic data for the background population, we calculated age- and sex-specific incidence rates and prevalence proportions of acquired hemolytic disorders for specified time periods.

Results

Our analysis included 5868 patients with acquired hemolytic disorders (2715 with AIHA, 112 CAD, 397 DIHA, 116 PNH, and 2154 AHNOS). The incidence rates per 100 000 person-years in 1980–1993 and 2008–2016 were 0.81 and 1.77 for AIHA, 0.31 and 0.12 for DIHA, and 0.04 and 0.08 for PNH, respectively. The 2008–2016 CAD incidence rate was 0.18/100 000 person-years, CAD diagnosis code was not defined before 1994. All incidence rates increased with age. The prevalence proportion per 100 000 persons in 1980 and 2015 was 2.52 and 17.01 for AIHA, 0.80 and 1.50 for DIHA, and 0.18 and 1.04 for PNH. CAD prevalence in 2015 was 1.04/100 000 persons.

Conclusion

Acquired hemolytic anemia incidence rates and prevalence proportions with the exception of DIHA are markedly increasing.