Spontaneous Remission in Paroxysmal Nocturnal Hemoglobinuria-Return to Health or Transition Into Malignancy?

Cost-effectiveness of ravulizumab compared with eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria in the Netherlands

OBJECTIVES

The aim of this study was to evaluate the cost-effectiveness of ravulizumab compared with eculizumab for the treatment of adult patients with paroxysmal nocturnal hemoglobinuria (PNH) in the Netherlands.

METHODS

A cost-effectiveness analysis was conducted based on a Markov cohort model simulating the course of patients with PNH with clinical symptom(s) indicative of high disease activity, or who are clinically stable after having been treated with eculizumab for at least the past six months. Costs, quality of life, and the incremental cost-effectiveness ratio (ICER) were estimated over a lifetime horizon from a Dutch societal perspective. Several additional analyses were performed, including a one-way sensitivity analysis, a probabilistic sensitivity analysis, and scenario analysis.

RESULTS

When compared with eculizumab, ravulizumab saves €266,833 and 1.57 quality adjusted life years (QALYs) are gained, resulting in a dominant ICER. Drug costs account for the majority of the total costs in both intervention groups. Cost savings were driven by the difference in total treatment costs of ravulizumab compared with eculizumab caused by the reduced administration frequency, accounting for 98% of the total cost savings. The QALY gain with ravulizumab is largely attributable to the improved quality of life associated with less frequent infusions and BTH events. At a willingness-to-pay threshold of €20,000/QALY, there is a 76.6% probability that ravulizumab would be cost-effective.

CONCLUSIONS

The cost reduction and QALY gain associated with the lower rates of BTH and less frequent administration make ravulizumab a cost-saving and clinically beneficial substitute for eculizumab for adults with PNH in the Netherlands.

Leukemic transformation during anti-tuberculosis treatment in aplastic anemia-paroxysmal nocturnal hemoglobinuria syndrome: A case report and review of literature

BACKGROUND

Accumulating evidence demonstrates that autoimmune hematopoietic failure and myeloid neoplasms have an intrinsic relationship with regard to clonal hematopoiesis and disease evolution. In approximately 10%-15% of patients with severe aplastic anemia (SAA), the disease phenotype is transformed into myeloid neoplasms following antithymocyte globulin plus cyclosporine-based immunosuppressive therapy. In some of these patients, myeloid neoplasms appear during or shortly after immunosuppressive therapy. Leukemic transformation in SAA patients during anti-tuberculosis treatment has not been reported.

CASE SUMMARY

A middle-aged Chinese female had a 6-year history of non-SAA and a 2-year history of paroxysmal nocturnal hemoglobinuria (PNH). With aggravation of systemic inflammatory symptoms, severe pancytopenia developed, and her hemoglobinuria disappeared. Laboratory findings in cytological, immunological and cytogenetic analyses of bone marrow samples met the diagnostic criteria for "SAA." Definitive diagnosis of disseminated tuberculosis was made in the search for infectious niches. Remarkable improvement in hematological parameters was achieved within 1 mo of anti-tuberculosis treatment, and complete hematological remission was achieved within 4 mo of treatment. Frustratingly, the hematological response lasted for only 3 mo, and pancytopenia reemerged. At this time, cytological findings (increased bone marrow cellularity and an increased percentage of myeloblasts that accounted for 16.0% of all nucleated hematopoietic cells), immunological findings (increased percentage of cluster of differentiation 34+ cells that accounted for 12.28% of all nucleated hematopoietic cells) and molecular biological findings (identification of somatic mutations in nucleophosmin-1 and casitas B-lineage lymphoma genes) revealed that "SAA" had transformed into acute myeloid leukemia with mutated nucleophosmin-1. The transformation process suggested that the leukemic clones were preexistent but were suppressed in the PNH and SAA stages, as development of symptomatic myeloid neoplasm through acquisition and accumulation of novel oncogenic mutations is unlikely in an interval of only 7 mo. Aggravation of inflammatory stressors due to disseminated tuberculosis likely contributed to the repression of normal and leukemic hematopoiesis, and the relief of inflammatory stressors due to anti-tuberculosis treatment contributed to penetration of neoplastic hematopoiesis. The concealed leukemic clones in the SAA and PNH stages raise the possibility of an inflammatory stress-fueled antileukemic mechanism.

CONCLUSION

Aggravated inflammatory stressors can repress normal and leukemic hematopoiesis, and relieved inflammatory stressors can facilitate penetration of neoplastic hematopoiesis.

Complement inhibition can decrease the haemostatic response in a microvascular bleeding model at multiple levels

Background

Haemostasis is a crucial process by which the body stops bleeding. It is achieved by the formation of a platelet plug, which is strengthened by formation of a fibrin mesh mediated by the coagulation cascade. In proinflammatory and prothrombotic conditions, multiple interactions of the complement system and the coagulation cascade are known to aggravate thromboinflammatory processes and increase the risk of arterial and venous thrombosis. Whether those interactions also play a relevant role during the physiological process of haemostasis is not yet completely understood. The aim of this study was to investigate the potential role of complement components and activation during the haemostatic response to mechanical vessel injury.

Methods

We used a microvascular bleeding model that simulates a blood vessel, featuring human endothelial cells, perfusion with fresh human whole blood, and an inducible mechanical injury to the vessel. We studied the effects of complement inhibitors against components of the lectin (MASP-1, MASP-2), classical (C1s), alternative (FD) and common pathways (C3, C5), as well as a novel triple fusion inhibitor of all three complement pathways (TriFu). Effects on clot formation were analysed by recording of fibrin deposition and the platelet activation marker CD62P at the injury site in real time using a confocal microscope.

Results

With the inhibitors targeting MASP-2 or C1s, no significant reduction of fibrin formation was observed, while platelet activation was significantly reduced in the presence of the FD inhibitor. Both common pathway inhibitors targeting C3 or C5, respectively, were associated with a substantial reduction of fibrin formation, and platelet activation was also reduced in the presence of the C3 inhibitor. Triple inhibition of all three activation pathways at the C3-convertase level by TriFu reduced both fibrin formation and platelet activation. When several complement inhibitors were directly compared in two individual donors, TriFu and the inhibitors of MASP-1 and C3 had the strongest effects on clot formation.

Conclusion

The observed impact of complement inhibition on reducing fibrin clot formation and platelet activation suggests a role of the complement system in haemostasis, with modulators of complement initiation, amplification or effector functions showing distinct profiles. While the interactions between complement and coagulation might have evolved to support haemostasis and protect against bleeding in case of vessel injury, they can turn harmful in pathological conditions when aggravating thromboinflammation and promoting thrombosis.

The Many Faces of Hemolysis

Hemolysis is a problem associated with a variety of red cell pathologies and physiologies not limited to the transfusion of cells. Various pathways lead to the observed outcomes when a hemolytic event occurs. Each event, and the pathway it follows, is based on characteristics of the red cell, the location in which the hemolysis occurs, and the interaction of the immune system. The severity of an event can be predicted with the knowledge of how these 3 factors interface. Although not all hemolytic events are alike, similarities may exist when the pathways overlap.

The burden of illness of patients with paroxysmal nocturnal haemoglobinuria receiving C5 inhibitors: clinical outcomes and medical encounters from the patient perspective

OBJECTIVES

To assess the clinical and healthcare resource burden among C5 inhibitor (C5i)-treated patients with paroxysmal nocturnal haemoglobinuria (PNH), using patient-reported data.

METHODS

This web-based, cross-sectional survey (01FEB2021-31MAR2021) of adults with PNH treated with eculizumab (France, Germany, UK) or ravulizumab (Germany) included: patient characteristics; treatment patterns/dosage; haematological outcomes (haemoglobin [Hb] levels, transfusions, thrombotic events, breakthrough haemolysis); and medical encounters. Treatment and Hb-level subgroup differences were assessed with statistical significance tests.

RESULTS

Among 71 patients, 98.6% were C5i-treated for ≥3 months. The majority (with reported Hb levels) had levels ≤12.0 g/dL (85.7%; n = 54/63). The mean Hb level was 10.2 g/dL (standard deviation [SD]: 2.0; median 10.0 g/dL). Treatment with above label-recommended doses was reported by 30.4% (eculizumab) and 5.3% (ravulizumab) of patients. Within the past 12 months among patients treated with C5i for ≥1 year: 24.1% had ≥1 transfusion; 3.2% had ≥1 thrombosis; and 28.6% had ≥1 breakthrough haemolysis. Among all patients, 26.8% and 31.0% reported emergency department/room [ER] and inpatient visits, respectively. Mean annual, per-patient all-cause medical encounters were: 0.5 (ER); 1.9 (inpatient); and overall outpatient visits ranged by setting from 2.0 to 6.4. Most encounters were PNH-related, with means of 0.4 (ER); 1.8 (inpatient); and 1.6-5.4 (outpatient). Primary haematological and medical encounter outcomes were similar between treatment as well as Hb-level subgroups, with almost no statistically significant differences.

CONCLUSIONS

Despite at least 3 months of C5i treatment, high proportions of patients with PNH reported low haemoglobin levels and required transfusions and hospitalizations, which suggests remaining unmet needs.

Inhibition of C3 with pegcetacoplan results in normalization of hemolysis markers in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematologic disorder characterized by complement-mediated hemolysis. C5 inhibitors (eculizumab/ravulizumab) control intravascular hemolysis but do not prevent residual extravascular hemolysis. The newly approved complement inhibitor, pegcetacoplan, inhibits C3, upstream of C5, and has the potential to improve control of complement-mediated hemolysis. The PADDOCK and PALOMINO clinical trials assessed the safety and efficacy of pegcetacoplan in complement inhibitor-naïve adults (≥ 18 years) diagnosed with PNH. Patients in PADDOCK (phase 1b open-label, pilot trial) received daily subcutaneous pegcetacoplan (cohort 1: 180 mg up to day 28 [n = 3]; cohort 2: 270–360 mg up to day 365 [n = 20]). PALOMINO (phase 2a, open-label trial) used the same dosing protocol as PADDOCK cohort 2 (n = 4). Primary endpoints in both trials were mean change from baseline in hemoglobin, lactate dehydrogenase, haptoglobin, and the number and severity of treatment-emergent adverse events. Mean baseline hemoglobin levels were below the lower limit of normal in both trials (PADDOCK: 8.38 g/dL; PALOMINO: 7.73 g/dL; normal range: 11.90–18.00 g/dL), increased to within normal range by day 85, and were sustained through day 365 (PADDOCK: 12.14 g/dL; PALOMINO: 13.00 g/dL). In PADDOCK, 3 serious adverse events (SAE) led to study drug discontinuation, 1 of which was deemed likely related to pegcetacoplan and 1 SAE, not deemed related to study drug, led to death. No SAE led to discontinuation/death in PALOMINO. Pegcetacoplan was generally well tolerated and improved hematological parameters by controlling hemolysis, while also improving other clinical PNH indicators in both trials. These trials were registered at www.clinicaltrials.gov (NCT02588833 and NCT03593200).

Clonal haematopoiesis of emerging significance

Clonal haematopoiesis (CH) is a ubiquitous feature of aging and provides mechanistic insight into the inextricable relationship between chronic inflammation and age-related diseases. Although CH confers a cumulative risk of subsequent haematological malignancy, particularly myeloid neoplasms, that risk is heavily mutation- and context-specific. Individuals with mutations in DNA damage response pathway genes receiving select cytotoxic therapies for solid tumours are among the highest risk groups for subsequent development of myeloid neoplasms. Multiple lines of evidence suggest that TET2-mutated macrophages causally contribute to cardiometabolic disease through the generation of proinflammatory cytokines. It is speculated that such CH-related inflammation is a shared driver of several other chronic diseases. Whether we can intervene in individuals with CH to diminish the risk of subsequent haematological malignancy or non-haematological disease remains to be seen. However, precision anti-cytokine therapies are a rational starting point to break the feedforward loop between clonal myeloid expansion, inflammation, and end-organ damage.

Secondary myelodysplastic syndrome and leukemia in acquired aplastic anemia and paroxysmal nocturnal hemoglobinuria

Acquired aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH) are pathogenically related nonmalignant bone marrow failure disorders linked to T-cell-mediated autoimmunity; they are associated with an increased risk of secondary myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Approximately 15% to 20% of AA patients and 2% to 6% of PNH patients go on to develop secondary MDS/AML by 10 years of follow-up. Factors determining an individual patient's risk of malignant transformation remain poorly defined. Recent studies identified nearly ubiquitous clonal hematopoiesis (CH) in AA patients. Similarly, CH with additional, non-PIGA, somatic alterations occurs in the majority of patients with PNH. Factors associated with progression to secondary MDS/AML include longer duration of disease, increased telomere attrition, presence of adverse prognostic mutations, and multiple mutations, particularly when occurring early in the disease course and at a high allelic burden. Here, we will review the prevalence and characteristics of somatic alterations in AA and PNH and will explore their prognostic significance and mechanisms of clonal selection. We will then discuss the available data on post-AA and post-PNH progression to secondary MDS/AML and provide practical guidance for approaching patients with PNH and AA who have CH.

Complement in Hemolysis- and Thrombosis- Related Diseases

The complement system, originally classified as part of innate immunity, is a tightly self-regulated system consisting of liquid phase, cell surface, and intracellular proteins. In the blood circulation, the complement system, platelets, coagulation system, and fibrinolysis system form a close and complex network. They activate and regulate each other and jointly mediate immune monitoring and tissue homeostasis. The dysregulation of each cascade system results in clinical manifestations and the progression of different diseases, such as sepsis, atypical hemolytic uremic syndrome, C3 glomerulonephritis, systemic lupus erythematosus, or ischemia–reperfusion injury. In this review, we summarize the crosstalk between the complement system, platelets, and coagulation, provide integrative insights into how complement dysfunction leads to hemopathic progression, and further discuss the therapeutic relevance of complement in hemolytic and thrombotic diseases.