Paroxysmal nocturnal hemoglobinuria clone in 103 Brazilian patients: diagnosis and classification

Clinical characteristics and management of paroxysmal nocturnal haemoglobinuria in Latin America: a narrative review

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, complement-associated, haematological disorder. The level of knowledge about the disease and its management varies around the world. This narrative review provides an overview of available clinical data on PNH in Latin America (LATAM). A search of the PubMed, EMBASE and LILACS/IBECS databases to February 2023, and addition of author-known articles, yielded 24 relevant published articles, the majority (n = 15) from Brazil. Fourteen articles were full papers; 10 were conference abstracts. The prevalence of PNH in Brazil is estimated at 1:237,000 inhabitants. Among blood samples sent for flow cytometry screening for suspected PNH in Brazil and Colombia, 14 - 30% were positive. There is suggestion that disease subtypes may differ among LATAM populations, with classical PNH more common in Brazilian patients and PNH with aplastic anaemia more common in Mexican patients. Median age at diagnosis of PNH ranged from 24 to 41 years. Common symptoms included fatigue, haemoglobinuria, and abdominal pain, although the symptom profile varied by subtype. Three available studies indicated that eculizumab was effective at reducing haemolysis, improving anaemia, and reducing the risk of thrombosis in patients with PNH with intravascular haemolysis. A consensus document from the Brazilian Association of Hematology, Hemotherapy and Cell Therapy RBC and Iron Committee provides guidance on identifying and managing PNH patients, including appropriate selection of patients for eculizumab. Additional data on the epidemiology, natural history and outcomes of patients with PNH in LATAM countries are needed to better understand the disease and its management throughout the region.

Clinicopathological Profile of Paroxysmal Nocturnal Hemoglobinuria among Omani Patients: A Case Series

We aimed to estimate the nature and prevalence of paroxysmal nocturnal hemoglobinuria (PNH) among Omani patients. We performed a retrospective review of all patients who were tested for PNH by flow cytometry at the Sultan Qaboos University Hospital, Muscat, between 2012 and 2019. Manifestations, treatment modalities, and outcomes were assessed. A total of 10 patients were diagnosed or were on follow-up for PNH (median age 22.5 years). Clinical manifestations included fatigue (80%) and anemia (70%). Six patients had classical PNH with hemolysis, three had PNH in the context of aplastic anemia, and one patient had subclinical PNH. The median total clone size (type II + III) for neutrophils was 95.5 (range: 1.5-97) (FLAER/CD24) and for monocytes was 91.6 (range = 0.04-99) (FLAER/CD14). Four patients had clone sizes > 50% at the time of diagnosis. The median follow-up period of the patients was 62 months (range = 8-204 months). One patient suffered thrombosis. Three patients were on immunosuppressant agents, five were initiated on eculizumab, and four had a bone marrow transplant. No deaths were reported in the cohort. The estimated average incidence of PNH among Omani patients was 1.5 per 5 000 000. PNH is rare in the Omani population. The predominant presentation is hemolytic anemia.

Analysis of baseline characteristics, disease burden and long-term follow-up of 167 patients with Paroxysmal Nocturnal Hemoglobinuria at a single center in Brazil

Paroxysmal nocturnal hemoglobinuria (PNH) can occur as a hemolytic form or small PNH clone found in a patient with bone marrow failure.

METHODS

Describe Brazilian retrospective PNH cohort and identify the impact of disease burden on long-term follow-up.

RESULTS

167 patients, mean age at diagnosis 28.4 (7.1-71.2 years), four years mean interval between onset of cytopenia/aplasia diagnosis and PNH clone detection. Patients were divided into 15 Classic PNH, 55 Hemolytic PNH with bone marrow hypoplasia (PNH/AA), and 97 Subclinical PNH (sc-PNH). Hypocellular bone marrow was found in 89.2%; 55 had hemoglobinuria and 22 thrombosis during monitoring. WBC PNH clone correlated with RBC PNH clone, LDH and cytopenia. Subclinical patients had lower median lower RBC clone (2.0% vs 24.0% vs 57.8%) and WBC clone (11.7% vs 58.8% vs 81.2%) than PNH/AA and Classic PNH, respectively. PNH granulocyte clone was 89.1% in thrombotic patients. Ten-year overall survival 80.4% and mortality in transplanted patients 9.6%. Sepsis was mortality cause in subclinical PNH (16/18, 88.8%), and thrombosis in hemolytic PNH (11/13, 84.6%).

CONCLUSION

Large PNH clones and LDH burden were associated with increased hemolysis and thrombosis risks, while young patients were associated with small PNH clones and subclinical form of the disease. Knowledge of the patient profile, the low risk associated with HSCT, and the use of long-term IST may be instrumental in the clinical management of PNH in restricted-resources countries.

Cost-Utility Analysis of Eculizumab for the Treatment of Paroxysmal Nocturnal Hemoglobinuria from the Perspective of the Brazilian Public Health System

OBJECTIVE

To perform a first cost-utility analysis of eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria from the perspective of the Brazilian Unified Health System.

METHODS

A Markov decision model was developed for 35-year-old patients with symptomatic paroxysmal nocturnal hemoglobinuria. We used a cycle length of one month and a time horizon of 20 years. The effectiveness measure was the quality-adjusted life year (QALY). Data were extracted from clinical trials, historical cohorts, and Unified Health System databases. Resource use and costs were estimated from the perspective of the Unified Health System. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

The estimated gain in effectiveness with the use of eculizumab was 1.08 QALY through the incremental cost of R$10,959,375.95. The incremental cost-effectiveness ratio was R$10,139,542.84 per QALY, being 331.92 times greater than the Brazilian gross domestic product per capita. In the deterministic sensitivity analysis, the parameters related to the utilities of health states were associated with greater impact in the model. The results of the probabilistic sensitivity analysis with 1000 simulations evidence that 100% of the simulations were not considered cost-effective with the arbitrated willingness to pay R$30,548.40 and R$91,645.20 per QALY.

CONCLUSIONS

The gain in effectiveness with the use of eculizumab was modest, associated with an unjustifiable incremental cost. Therefore, eculizumab is not a cost-effective drug compared with the current standard of care in the treatment of paroxysmal nocturnal hemoglobinuria from the Brazilian Unified Health System perspective.

A comparative analysis of clinical characteristics of patients with paroxysmal nocturnal hemoglobinuria between Asia and Europe/America

To accurately analyze the clinical characteristics of paroxysmal nocturnal hemoglobinuria (PNH) in different ethnic backgrounds, we retrieved all retrospective studies on clinical characteristics of PNH with a median follow-up period >60 months published after 2000, analyzed the clinical characteristics of PNH patients in Asia and European/America, and statistically compared enumeration data in these studies. We included 1665 patients in this analysis. The proportion of female patients in Asia was significantly lower than that in Europe/America (P = 0.000). Incidence rates of hemoglobinuria and thromboembolism in Asia were significantly lower than in Europe/America (both P values were 0.000). Within the subgroups of patients with thromboembolism, Asian patients had a higher proportion of arterial thrombosis while Western patients had a higher proportion of abdominal venous thrombosis. Bone marrow failure was not clearly defined in most studies. The proportion of patients with pancytopenia was higher in China than in France (P = 0.048). The total death rates were similar in both ethnic groups (P > 0.05). In Europe/America the major cause of death was thromboembolism and in Asian countries was serious infections. Differences in population characteristics of PNH patients among different ethnic groups indicate the possibility of differential pathogenesis and may be informative for treatment decisions.