Paroxysmal nocturnal hemoglobinuria (PNH) is a rare nonmalignant clonal hematological disorder that is characterized by a deficiency of the GPI‐linked complement regulators on the membrane of ...hematopoietic cells, which renders them susceptible to complement‐mediated damage. Intravascular hemolysis (IVH), increased tendency for thrombosis, and bone marrow failure constitutes hallmark features of the disease and are associated with high morbidity and mortality. The introduction of C5 inhibitors radically changed disease outcomes, offering a near‐normal life expectancy to PNH patients. However, residual IVH and extravascular hemolysis (EVH) continue to occur during C5‐inhibitor treatment, leaving a significant proportion of patients' anemic and some remaining transfusion dependent. Quality of life (QoL) has also been an issue with the regular intravenous (IV) administrations of the currently licensed C5 inhibitors. This has led to the exploration and development of novel agents, targeting different parts of the complement cascade, or having different formulations allowing for self‐administration. Longer‐acting and subcutaneous formulations of C5 inhibitors have shown equal safety and efficacy, whereas the development of proximal complement inhibitors is changing completely the therapeutic landscape of PNH, limiting both IVH and EVH and showing superior efficacy over C5 inhibitors, especially in improving haemoglobin. Combination treatments have also been tested with promising results. This review summarizes the current therapeutic options, gaps in anti‐complement therapy and discusses emerging therapeutic approaches for PNH.
Pathophysiology of PNH and complement inhibitors.
Paroxysmal nocturnal hemoglobinuria (PNH) is characterised by complement-mediated intravascular hemolysis (IVH) due to absence of complement regulators CD55 and CD59 on affected erythrocytes. ...Danicopan is a first-in-class oral proximal, complement alternative pathway factor D (FD) inhibitor. Therapeutic FD inhibition was designed to control IVH and prevent C3-mediated extravascular hemolysis (EVH). In this open-label, phase 2, dose-finding trial, 10 untreated hemolytic PNH patients received danicopan monotherapy (100-200 mg thrice daily). Endpoints included change in lactate dehydrogenase (LDH) at day 28 (primary) and day 84 and hemoglobin. Safety, pharmacokinetics/pharmacodynamics, and patient-reported outcomes were measured. Ten patients reached the primary endpoint; two later discontinued: one for a serious adverse event (elevated aspartate aminotransferase/alanine aminotransferase coincident with breakthrough hemolysis, resolving without sequelae) and one for personal reasons unrelated to safety. Eight patients completed treatment. IVH was inhibited, demonstrated by mean decreased LDH (5.7 times upper limit of normal ULN at baseline vs 1.8 times ULN day 28 and 2.2 times ULN day 84; both p.
The complex pathophysiologic interplay between SARS-CoV-2 infection and complement activation is the subject of active investigation. It is clinically mirrored by the occurrence of exacerbations of ...complement mediated diseases during COVID-19 infection. These include complement-mediated hemolytic anemias such as paroxysmal nocturnal hemoglobinuria (PNH), autoimmune hemolytic anemia (AIHA), particularly cold agglutinin disease (CAD), and hemolytic uremic syndrome (HUS). All these conditions may benefit from complement inhibitors that are also under study for COVID-19 disease. Hemolytic exacerbations in these conditions may occur upon several triggers including infections and vaccines and may require transfusions, treatment with complement inhibitors and/or immunosuppressors (i.e., steroids and rituximab for AIHA), and result in thrombotic complications. In this manuscript we describe four patients (2 with PNH and 2 with CAD) who experienced hemolytic flares after either COVID-19 infection or SARS-Cov2 vaccine and provide a review of the most recent literature. We report that most episodes occurred within the first 10 days after COVID-19 infection/vaccination and suggest laboratory monitoring (Hb and LDH levels) in that period. Moreover, in our experience and in the literature, hemolytic exacerbations occurring during COVID-19 infection were more severe, required greater therapeutic intervention, and carried more complications including fatalities, as compared to those developing after SARS-CoV-2 vaccine, suggesting the importance of vaccinating this patient population. Patient education remains pivotal to promptly recognize signs/symptoms of hemolytic flares and to refer to medical attention. Treatment choice should be based on the severity of the hemolytic exacerbation as well as of that of COVID-19 infection. Therapies include transfusions, complement inhibitor initiation/additional dose in the case of PNH, steroids/rituximab in patients with CAD and warm type AIHA, plasma exchange, hemodialysis and complement inhibitor in the case of atypical HUS. Finally, anti-thrombotic prophylaxis should be always considered in these settings, provided safe platelet counts.
The distinction between acquired aplastic anemia (AA) and hypocellular myelodysplastic syndrome (hMDS) is often difficult, especially nonsevere AA. We postulated that somatic mutations are present in ...a subset of AA, and predict malignant transformation. From our database, we identified 150 AA patients with no morphological evidence of MDS, who had stored bone marrow (BM) and constitutional DNA. We excluded Fanconi anemia, mutations of telomere maintenance, and a family history of BM failure (BMF) or cancer. The initial cohort of 57 patients was screened for 835 known genes associated with BMF and myeloid cancer; a second cohort of 93 patients was screened for mutations in ASXL1, DNMT3A, BCOR, TET2, and MPL. Somatic mutations were detected in 19% of AA, and included ASXL1 (n = 12), DNMT3A (n = 8) and BCOR (n = 6). Patients with somatic mutations had a longer disease duration (37 vs 8 months, P < .04), and shorter telomere lengths (median length, 0.9 vs 1.1, P < .001), compared with patients without mutations. Somatic mutations in AA patients with a disease duration of >6 months were associated with a 40% risk of transformation to MDS (P < .0002). Nearly one-fifth of AA patients harbor mutations in genes typically seen in myeloid malignancies that predicted for later transformation to MDS.
•Acquired mutations of myeloid-related genes are present in a proportion of AA patients.•Somatic mutations in AA predict higher risk of transformation to MDS.
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