Hemolytic Paroxysmal Nocturnal Hemoglobinuria Research Articles

Iptacopan Efficacy and Safety to Treat Paroxysmal Nocturnal Hemoglobinuria (PNH): A Systematic Review and Meta-Analysis.

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon blood condition caused by complement-mediated hemolysis. In early clinical studies, iptacopan, an oral factor B inhibitor, showed promise in treating PNH. This systematic review aimed to compile information on the effectiveness and safety of iptacopan for PNH.A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. The Medline, Embase, PubMed, and Cochrane Central databases were searched for randomized controlled trials (RCTs) and observational studies that evaluated iptacopan for PNH. The primary efficacy outcomes were hemoglobin and lactate dehydrogenase (LDH) changes. A fixed-effects model was used for the meta-analysis. Six studies (three prospective cohorts, two RCTs, and one non-randomized trial) were included, comprising 197 patients. Iptacopan therapy significantly increased hemoglobin levels (mean differences (MD) = 12.98 g/L; 95% CI: 11.82-14.13; p < 0.0001) and decreased LDH (MD = -83.55 IU/L; 95% CI: -83.77 to -83.34; p < 0.0001). Subgroup analyses revealed more significant hemoglobin increases in European vs. Asian populations, studies with baseline Hb > 10 g/dL vs. < 10 g/dL, and studies lasting > 24 weeks vs. ≤ 24 weeks. LDH decreases were more pronounced in studies with baseline LDH > 500 IU/L vs. < 500 IU/L. The incidence of adverse events ranged from 66% to 90%, with the most common being headache, nasopharyngitis, and diarrhea. Serious adverse events occurred in 0-20% of patients across studies. Only one patient withdrew because adverse effects were reported across all studies.Preliminary data support iptacopan's effectiveness in improving hemoglobin levels and lowering hemolysis in PNH, both as a monotherapy and in combination with usual treatment. The safety profile appears to be excellent, with a minimal incidence of major adverse events and treatment discontinuation. Further studies are needed to validate the effectiveness and safety of larger, longer-term trials. Iptacopan is a viable oral therapy option for PNH.

Crovalimab: First Approval.

Crovalimab (®; PiaSky) is a humanized, anti-complement component C5 (anti-C5) recycling monoclonal antibody developed by Chugai Pharmaceutical, in collaboration with Roche, which is being investigated for the treatment of complement-mediated diseases, including paroxysmal nocturnal haemoglobinuria (PNH), atypical haemolytic uremic syndrome, lupus nephritis and sickle cell disease. Crovalimab targets C5, inhibiting its cleavage to C5a and C5b, thus blocking the terminal complement pathway and preventing intravascular haemolysis in PNH. Crovalimab is designed to bind to the antigen repeatedly, resulting in sustained complement inhibition at a lower dosage, and allowing for once-monthly subcutaneous administration. In February 2024, subcutaneous crovalimab received its first approval in China for the treatment of adolescents and adults (aged ≥ 12 years) with PNH who have not been previously treated with complement inhibitors. Crovalimab has since been approved in Japan in March for use in the treatment of PNH, including in treatment-naïve and previously treated patients. Crovalimab is also under regulatory review for the treatment of naïve and previously treated patients with PNH in multiple countries, including the USA and the European Union. This article summarizes the milestones in the development of crovalimab leading to this first approval in China for the treatment of PNH.

Incremental Burden Associated with Dose Escalation in Patients with Paroxysmal Nocturnal Hemoglobinuria Treated with Complement Inhibitors

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by complement-mediated hemolytic anemia. Terminal complement component C5 inhibitors eculizumab (ECU) and ravulizumab (RAVU) inhibit the formation of membrane attack complex, and thereby ameliorates intravascular hemolysis in PNH. Some patients exhibit breakthrough intravascular hemolysis near the end of 14-day treatment cycle for ECU or 8-week treatment cycle for RAVU. To manage breakthrough hemolysis, different treatment strategies may be attempted in the clinical practice, including shortening the dosing interval and/or increasing the dose of ECU and RAVU. This study aimed to estimate the incremental costs associated with dose escalation in patients with PNH treated with ECU or RAVU in the US. Methods: Adult (age ≥18 years) patients with PNH (ICD-10-CM code D59.5) treated with ECU or RAVU from health plan claims data (01/01/2011 to 09/30/2022) with ≥3 months of continuous health plan coverage following the first claim for ECU or RAVU were included in this retrospective cohort study. Dosing patterns were investigated during the maintenance phase. Consistent with label-recommended dosing schedule, the maintenance phase started from day 29 and day 15 post-first claim for ECU and RAVU, respectively, until the earliest of treatment discontinuation/loss to follow-up/end of data. Dose escalation for ECU was defined as 1) an increased dose (i.e., 1,200 or 1,500 mg) and/or 2) an increased infusion frequency (i.e., ≥2 infusions within 12 days). Patient-weight information was not available; dose escalation for RAVU was defined as an increased infusion frequency (i.e., ≥2 infusions within 49 days). All-cause and PNH-related direct healthcare costs measured during maintenance phase for the overall cohort and subgroup of patients with dose escalation were assessed for ECU and RAVU separately. Incremental costs associated with dose escalation in the pre vs. post dose escalation period were assessed for ECU and RAVU separately; p-values from Wilcoxon signed-rank tests were reported. Results: A total of 278 patients treated with ECU (mean± SD age, 42±13 years; 60% female) were included in the overall cohort and a subgroup of 151 patients were observed with a dose escalation (mean±SD age, 41±13 years; 58% female). For the overall ECU cohort (N=278), during a mean follow-up of 23 months, total all-cause and PNH-related costs (mean±SD) were $67,650±$32,518 and $65,751±$31,379 per patient per month (PPPM), respectively. In the subgroup of patients with dose escalation (N=151), over a mean follow-up of 30 months, total all-cause and PNH-related costs (mean±SD) were $71,466±$33,452 and $69,471±$31,595 PPPM, respectively. In the overall cohort and subgroup of patients with dose escalation, PNH-related treatment costs represented 90% and 92% of total all-cause costs respectively. A total of 171 patients treated with RAVU (mean± SD age, 39±12 years; 43% female) were included in the overall cohort and a subgroup of 26 patients were observed with a dose escalation (i.e., increased infusion frequency only) (mean± SD age, 37±11 years; 54% female). For the overall RAVU cohort (N=171), during a mean follow-up of 17 months, total all-cause and PNH-related costs (mean±SD) were $50,779±$26,258 and $49,213±$25,751 PPPM, respectively. In the subgroup of patients with dose escalation (N=26), over a mean follow-up of 20 months, total all-cause and PNH-related costs (mean±SD) were $52,819±$20,965 and $50,740±$20,837 PPPM, respectively. In the overall cohort and subgroup of patients with dose escalation, PNH-related treatment costs represented 93% and 91% of total all-cause costs, respectively. Incremental costs (mean cost differences) associated with dose escalation for ECU were of $16,861 (p&amp;lt;0.01) and $15,956 (p&amp;lt;0.01) PPPM for all-cause and PNH-related total costs, respectively; and for RAVU were of $4,950 (p&amp;lt;0.05) and $3,738 (p=0.06) PPPM for all-cause and PNH-related total costs, respectively (Figures 1A and 1B). Conclusions: In this study of PNH patients treated with C5 inhibitors, dose escalation was associated with significant incremental costs for both ECU and RAVU. Further research is warranted to clarify the reasons for dose escalation, which may potentially indicate an unmet clinical need for more efficacious treatment options to help prevent breakthrough symptoms and reduce the burden of PNH.

Clinical Breakthrough Hemolysis (BTH) during Monotherapy with the Oral Factor B Inhibitor Iptacopan Is Generally Not Severe and Managed without Treatment Discontinuation: 48-Week Data from the Phase III Apply-PNH and Appoint-PNH Trials in Paroxysmal Nocturnal Hemoglobinuria (PNH)

Background: In PNH, BTH is characterized by the re-emergence of intravascular hemolysis (IVH) despite ongoing complement inhibition and is recognized by the reappearance of IVH/PNH signs/symptoms, coupled with a marked increase in lactate dehydrogenase (LDH) and sharp decrease in hemoglobin (Hb). Iptacopan is the first oral proximal complement inhibitor targeting factor B in the alternative pathway and has shown efficacy and safety in complement inhibitor-naïve PNH patients (pts; APPOINT-PNH; NCT04820530) and pts with persistent anemia despite anti-C5 treatment (APPLY-PNH; NCT04558918). In the APPLY-PNH 24-week (wk) analysis, iptacopan monotherapy showed superiority in the adjusted annualized rate of clinical BTH vs C5 inhibitors. Aim: We report the proportion of pts with clinical BTH, exposure-adjusted occurrence rates and BTH characteristics during iptacopan monotherapy in the Phase III APPLY-PNH and APPOINT-PNH trials (study completion [48-wk data]: 6 March and 18 April 2023, respectively). Methods: The prespecified protocol criteria for clinical BTH were LDH &amp;gt;1.5 × upper limit of normal (ULN) and increased vs the last 2 assessments, plus a ≥2 g/dL Hb decrease (vs the last assessment or within 15 days) or significant PNH signs/symptoms. All BTH was classed as an adverse event and evaluated for severity (investigator assessment) and seriousness (per protocol). In APPLY-PNH, adults who had received anti-C5 therapy for ≥6 months and had mean Hb &amp;lt;10 g/dL were randomized to receive oral iptacopan 200 mg twice daily or continue their anti-C5 regimen for 24 wks (randomized treatment period [RTP]). In APPOINT-PNH, adult complement inhibitor-naïve pts with mean Hb &amp;lt;10 g/dL and mean LDH &amp;gt;1.5 × ULN received iptacopan 200 mg twice daily for 24 wks. Both trials then had extension periods in which all pts could receive iptacopan monotherapy for another 24 wks. Results: In APPLY-PNH, 61/62 pts in the iptacopan arm continued iptacopan in the extension period and 34/35 in the anti-C5 arm switched to iptacopan. All 40 pts in APPOINT-PNH entered the extension period. When these 48-wk trials completed, 136 pts had received iptacopan with varying exposure (total exposure ~111 pt-years), of whom 9 had clinical BTH (10 events, Table). Two pts were in APPOINT-PNH (2/40, 2 events) and 7 in APPLY-PNH (7/96, 8 events). Of the iptacopan-treated pts in APPLY-PNH, 2 had BTH in the RTP; 1 of these pts plus 5 others had BTH in the extension period (including 1 who switched from anti-C5 to iptacopan at Wk 24). The exposure-adjusted occurrence rate of clinical BTH on iptacopan was 11.0 events per 100 pt-years in APPLY-PNH (95% confidence interval [CI] 5.2‒23.3) and 5.2 events per 100 pt-years in APPOINT-PNH (95% CI 1.3‒20.5). In the 24-wk APPLY-PNH RTP, 6/35 pts in the anti-C5 arm had clinical BTH (11 events); the exposure-adjusted occurrence rate was 66.9 events per 100 pt-years (95% CI 25.0‒178.9), which is &amp;gt;6 times higher than the rates on iptacopan. Of the 10 clinical BTH events reported on iptacopan, all were mild or moderate except 1 severe (and serious) event despite large PNH RBC clone sizes of &amp;gt;90% reported before 5/8 events with available clone size data. The impact of BTH on Hb was generally transient (Figure). Potential complement-amplifying conditions (CACs) were identified for 8 clinical BTH events during iptacopan treatment; the severe event was associated with COVID-19 and the temporal appearance of cold agglutinins. No pts discontinued iptacopan because of clinical BTH. RBC transfusions were the most common intervention; 1 pt received a 900 mg dose of eculizumab. In the anti-C5 arm in the APPLY-PNH RTP, 1/11 BTH events was severe and 2/11 were associated with potential CACs. Conclusions: In Phase III trials, 136 PNH pts received iptacopan monotherapy and few pts had clinical BTH, with severity being comparable to that with anti-C5 despite PNH RBC clone sizes &amp;gt;90%. Most clinical BTH events on iptacopan were associated with potential CACs; BTH was manageable with no intervention or RBC transfusion and without iptacopan discontinuation. The exposure-adjusted occurrence rates support our prior finding of a significantly lower adjusted annualized rate of clinical BTH with iptacopan vs anti-C5. BTH must be monitored with any complement inhibitor, but these data show that BTH was infrequent on iptacopan and support the positive safety profile of proximal complement inhibition with oral iptacopan monotherapy in hemolytic PNH.

Factor B Inhibition with Oral Iptacopan Monotherapy Demonstrates Sustained Long-Term Efficacy and Safety in Anti-C5-Treated Patients (pts) with Paroxysmal Nocturnal Hemoglobinuria (PNH) and Persistent Anemia: Final 48-Week Results from the Multicenter, Phase III APPLY-PNH Trial

Drs Roeth and Kulasekararaj contributed equally as authors. Background: Iptacopan is the first oral complement inhibitor that acts proximally in the complement system to target factor B in the alternative pathway. Iptacopan has shown efficacy/safety in PNH pts with persistent anemia despite anti-C5 therapy and complement inhibitor-naive pts. In the Phase III APPLY-PNH trial (NCT04558918), iptacopan monotherapy led to clinically meaningful hemoglobin (Hb) increases and normal/near-normal Hb levels in a majority of pts, transfusion avoidance and improved pt-reported fatigue, showing superiority vs C5 inhibitors at Week (Wk) 24. Aim: We report the final APPLY-PNH data after a 24-wk extension period in which all pts received iptacopan monotherapy (study completion: 6 March 2023). Methods: Adult PNH pts (mean Hb &amp;lt;10 g/dL, receiving anti-C5 therapy for ≥6 months) were randomized to receive iptacopan 200 mg twice daily or continue their anti-C5 regimen for 24 wks. Pts could then opt to enter an extension period; pts in the iptacopan arm received iptacopan for another 24 wks and pts who had been receiving anti-C5 switched to iptacopan monotherapy. Results: In the extension period, 95 pts received iptacopan: 61/62 in the iptacopan arm (1 discontinued iptacopan in the randomized period because of pregnancy) and 34/35 in the anti-C5-to-iptacopan arm (1 did not enter the extension period [investigator's decision]). In the iptacopan arm, the improvements at 24 wks were sustained at 48 wks, with maintenance of increased Hb, normal/near-normal mean Hb levels (Figure), improved Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) scores, decreased absolute reticulocyte counts (ARCs) and transfusion avoidance (Table). Pts who switched from anti-C5 to iptacopan had rapid changes in Hb, FACIT-F and ARC, achieving comparable improvements to the iptacopan arm. Mean Hb levels at Wk 48 were 12.2 and 12.1 g/dL in the iptacopan and anti-C5-to-iptacopan arms, respectively (standard deviations 1.6 and 1.4). At Wk 48, the adjusted mean change from baseline in the iptacopan arm was +3.35 g/dL for Hb, +9.80 FACIT-F points and −106.26 × 10 9/L for ARC. In the anti-C5-to-iptacopan arm, the adjusted mean change from baseline at Wk 48 was +3.36 g/dL for Hb, +10.96 FACIT-F points and −107.95 × 10 9/L for ARC (adjusted mean difference in change from baseline at Wk 48 vs Wk 24: +3.02 g/dL, +10.79 points and −102.29 × 10 9/L, respectively). Transfusion avoidance was achieved by 93.5% of pts in the iptacopan arm (Wks 2 to 48) and 94.1% in the anti-C5-to-iptacopan arm (Wks 26 to 48). Mean lactate dehydrogenase levels were generally maintained &amp;lt;1.5 × upper limit of normal in both arms. In the trial, 6/62 pts in the iptacopan arm had clinical breakthrough hemolysis (BTH). One pt in the anti-C5-to-iptacopan arm had clinical BTH after switching to iptacopan. BTH resolved without changing iptacopan dosing. Three pts had major adverse vascular events (MAVEs; randomized period: 1 serious transient ischemic attack [TIA]; extension period: 1 non-serious TIA, 1 serious portal vein thrombosis [PVT]). The pt with PVT had a history of PVT and discontinued heparin prior to the MAVE. All MAVEs were considered unrelated to iptacopan and resolved without changing iptacopan dosing. After 48 wks in the iptacopan arm, the most frequently reported treatment-emergent adverse events (TEAEs) were COVID-19 (29.0% of pts), headache (19.4%), diarrhea (16.1%) and nasopharyngitis (14.5%). There were no deaths, no serious hemolysis TEAEs on iptacopan, no serious infections caused by N. meningitidis, S. pneumoniae or H. influenzae and no pts discontinued treatment because of TEAEs. Conclusions: Long-term data from the Phase III APPLY-PNH trial show a durable response to iptacopan monotherapy in anti-C5-treated PNH pts with persistent anemia. Pts who received iptacopan for 48 wks had sustained improvements in multiple hematological and clinical outcomes, including maintenance of increased Hb, mean normal/near-normal Hb levels, transfusion avoidance and decreased pt-reported fatigue; these benefits quickly emerged in the anti-C5-to-iptacopan arm, supporting the benefit of switching from C5 inhibitors to iptacopan monotherapy. The data indicate good control of hemolysis by iptacopan and a similar safety profile at Wk 48 vs Wk 24. Our findings continue to support oral iptacopan monotherapy as a potentially practice-changing treatment for hemolytic PNH.

Avatrombopag Is Effective in First-Line Treatment of Severe Aplastic Anemia: Early Outcomes of a Prospective Study

Acquired severe aplastic anemia (SAA) is a life-threatening bone marrow failure disease and its pathogenesis involves T cell-mediated autoimmunity. Antithymocyte globulin (ATG) and cyclosporine based immunosuppressive therapy (IST) is effective for patients not eligible for hematopoietic stem cell transplant, and the response rate is 60-70%. Complete hematological response (CR) predicts better survival of patients received IST treatment, but only a few patients achieve CR within 6 months (5% at 3 months and 12-17% at 6 months). Thrombopoietin receptor agonist (TPO-RA) eltrombopag improves the overall response (OR) rate and CR rate of SAA patients when combined with IST, but its hepatotoxicity is still worrying. Avatrombopag is another small-molecule TPO-RA without hepatic toxicity. We previously found that SAA patients received avatrombopag and IST as first-line treatment showed both higher CR rate and OR rate at 3 and 6 months. To validate our findings, a prospective, single-arm study of avatrombopag and IST for newly diagnosed SAA was carried out (NCT05720234). There were 25 patients enrolled in the study by June 31, 2023, including 21 SAA patients and 4 very severe aplastic anemia patients. Patients were diagnosed as AA within 6 months and received ATG, cyclosporine and avatrombopag as first-line treatment. Avatrombopag was administered at the first day of ATG initiation at dose of 60mg per day for patients weight ≥ 50kg and 40mg per day for patients weight &amp;lt; 50kg. ATG was given for 5 consecutive days. Cyclosporine was given orally at dose of 3.5-5mg/kg.d. There were 15 males and 10 males, at a median age of 37 years old. Eighteen patients achieved the end-point of 3 months and 10 patients achieved end-point of 6 months. There were 15 patients achieved hematologic response at 3 months (83.3%), including 5 complete responders (27.8%) and 10 partial responders. The overall response rate at 6 months was 80%, and CR rate was 60%. One patient evolved to hemolytic paroxysmal nocturnal hemoglobinuria at 3 months, with normal count of platelet and white blood cell. In conclusion, the addition of avatrombopag to IST as first-line treatment showed earlier hematologic response and higher complete response rate for patients with SAA.

Effect of Eculizumab on Iron Metabolism in Transfusion-independent Patients With Paroxysmal Nocturnal Hemoglobinuria

Effect of Eculizumab on Iron Metabolism in Transfusion-independent Patients With Paroxysmal Nocturnal Hemoglobinuria

Complement Inhibition in Paroxysmal Nocturnal Hemoglobinuria (PNH): A Systematic Review and Expert Opinion from Central Europe on Special Patient Populations.

Hemolysis in paroxysmal nocturnal hemoglobinuria (PNH) is complement-mediated due to the lack of complement inhibitors in the hemopoietic cell membranes, making complement inhibition the best approach to manage PNH. Three complement inhibitors are approved by the European Medicines Agency as targeted therapy for PNH: eculizumab and ravulizumab, two humanized monoclonal antibodies targeting the same complement 5 (C5) epitope, approved in 2007 and 2019, respectively, and the more recently approved cyclic peptide, the complement 3 (C3) inhibitor pegcetacoplan. Although national and international PNH treatment guidelines exist, they do not take into consideration the latest clinical trial evidence. Given the lack of evidence-based data for some clinical situations encountered in real life, we identified specific populations of patients who may benefit from switching to proximal C3 from terminal C5 inhibition. The expert recommendations presented here were created using a Delphi-like process by a group of expert PNH specialists across Central Europe. Based on an initial advisory board meeting discussion, recommendations were prepared and reviewed as part of a Delphi survey to test agreement. Using a systematic approach, literature databases were searched for relevant studies, and 50 articles were reviewed by the experts and included as supporting evidence. Implementation of these recommendations uniformly across healthcare institutions will promote the best use of complement inhibition in managing PNH, and has the potential to positively impact patient outcomes in Central Europe and worldwide.

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.

Clinico-Molecular Risk Factors and Management of Thrombosis in a Large Real-Life Cohort of Patients with Paroxysmal Nocturnal Hemoglobinuria in the New Era of Anti-Complement Inhibitors and Doacs

The increased propensity for thrombotic events (TE) is well established in patients with paroxysmal nocturnal hemoglobinuria (PNH) and represents the main cause of disease morbidity/mortality. While the precise pathogenesis of TE remains ill-defined and likely multifactorial, cases with fully blown hemolytic PNH clones show the highest risk for such complications, often occurring in atypical localizations including the hepatic circulation (e.g., Budd-Chiari syndrome, BCS). The introduction of anti-complement therapy greatly abated hemolysis and thrombosis, demonstrating the crucial involvement of the underlying hemolytic process in triggering TE. Despite the current availability of PNH-directed treatment, a scarcity of data exist on anticoagulation and specifically on the efficacy of direct oral anticoagulants (DOACs) in this setting. Here, we took advantage of a large, real-life cohort of patients with classical hemolytic PNH to unravel determinants of thrombosis and decipher anticoagulation strategies in cases developing TE. Among 106 PNH cases (M:F ratio 0.86, median age 39 years, IQR 26-58) followed-up for a median of 68 months (95% CI 50-92), 42% were primary and 58% had antecedent aplastic anemia. Median granulocyte clone size at diagnosis was 71% (46-90) with the majority of cases classified as type III dominant red blood cells (RBCs) clone (81%) by flow cytometric analysis.1In total, 77% of cases harbored PIGA mutations by multi-amplicon deep NGS at a median ploidy-adjusted VAF of 20% (9-33), of whom 58% presenting multiple hits (clonal mosaicism).1 A total of 33 patients (31%) experienced TE, of which 84% occurred as the initial disease manifestation prompting to seek medical attention, 13% during a temporary discontinuation of anti-complement treatment (e.g., preparation to allogeneic bone marrow transplant), and only 3% (N=1) during treatment. Overall, the majority of patients had TE originating in the venous system (91%), arterial cerebrovascular district (6%) or both (3%). TE occurred typically in unusual sites with BCS as the most frequent (34%) followed by deep vein thrombosis (DVT, 20%), DVT complicated by pulmonary embolism (14%), splanchnic (14%), cerebral sinuses and superficial veins (9% each). No differences in disease ontogenesis (primary vs secondary to AA), and baseline variables such as age, PNH clone size, gender, PIGA mutations (presence, type and clonal burden), blood counts, reticulocytes, LDH, creatinine and transaminases were observed. Interestingly, patients experiencing TE were more commonly presenting with type II RBC phenotype (36% vs 13%; p=.027), had median lower albumin (4 vs 4.5 g/dL; p<.001) and elevated D-dimers (1520 vs 325 ng/mL; p=.003) as compared to non-TE cases. Patients with superficial TE were promptly started on anti-complement treatment, while the others improved with additional anticoagulation. One patient with portal vein thrombosis had severe thrombocytopenia and eventually died due to progressive BCS. Anticoagulation strategy consisted of warfarin (50%), DOACs (29%) and low molecular weight heparin (LMWH, 21%) with a median treatment duration of 44 months (17-73). LMWH was preferred in patients with thrombocytopenia (median platelets 45 vs 102x109/L in cases receiving other therapeutics; p=.03). In 1 patient, warfarin was switched to DOACs for prolonged treatment, 2 BCS cases underwent TIPS, and in 1 case with DVT an inferior vena cava filter was positioned because of the concomitant diagnosis of myeloproliferative neoplasm with MPLW515L. Recurrence of TE under anticoagulants was noted in only 2 cases receiving warfarin, whereas 7 (N=5 warfarin/ 2 DOACs) experienced bleeding. Two patients on DOACs had acute rectal hemorrhage with additional bleeding risk factors (clopidogel, ulcerative colitis). No thrombotic recurrence was observed in all 9 patients treated with DOACs at a median observation time of 24 months (12-95). While previously TE prompted lifelong anticoagulation, the control of the underlying disease with anti-complement drugs enabled its successful discontinuation in 42% of patients without any TE recurrence at a median time of 50 months (15-90). This is the largest hemolytic PNH series ever reported detailing clinico-molecular risk factors, characteristics of TE and their management in the era of anti-complement therapy and DOACs, whose use in such a setting warrants attention and further studies.

Complement Biomarkers for Tracking Breakthrough Hemolysis in Paroxysmal Nocturnal Hemoglobinuria (PNH) Patients Treated with Last-Generation Complement Inhibitors

Background After the introduction of complement inhibitors targeting C5 (eculizumab, ravulizumab), the field of PNH has been revolutionized by the development of proximal complement inhibitors targeting C3 (pegcetacoplan), factor D (danicopan) or factor B (iptacopan). Since they are able to prevent C3-mediated extravascular hemolysis in addition to inhibit MAC-mediated intravascular hemolysis, these compounds result in better hematological responses, but breakthrough hemolysis (BTH) emerged as a possible adverse event. CH50, free-C5 and free-eculizumab have been used as assays useful to monitor therapeutic inhibition, but they remain specific for anti-C5 therapies only. Methods We investigated complement biomarkers searching for their association with clinically meaningful hemolysis. Instead of looking for residual complement activity, we tracked in vivo complement activation through the complement breakdown fragments sC5b-9, Bb, C4d (assessing terminal, alternative and classical pathways, respectively), and erythrocyte-bound C3d. We analyzed serial samples collected from 2 untreated patients who then received danicopan in monotherapy (total samples 83), and from 8 patients initially treated with eculizumab (total samples n=19), who then received iptacopan (total samples 263, combination therapy with eculizumab n=236, and monotherapy n=27). Data were correlated with clinical and laboratory hemolysis (lactate dehydrogenase, LDH). Results Samples collected from untreated patients highlight massive and broad complement activation, with increased sC5b-9 (2478±2151 ng/mL; n.r. 20-172), increased Bb (4.578±0.494 µg/mL; n.r. 0.060-0.566), but normal C4d (0.036±0.023 µg/mL; n.r. 0.033-0.219), demonstrating that it is the alternative pathway which enables the terminal pathway eventually causing hemolysis in PNH. Patients on the terminal inhibitor eculizumab treatment showed elevated Bb (3.378±2.124 µg/mL), and elevated sC5b-9 (1273±1007 ng/mL), even if this latter seems slightly lower as compared to that of untreated patients. Erythrocyte-bound C3d was detectable in all samples (32.3±19.2% C3d+ erythrocytes, n=56; n.r. <0.1), consistent with the notion that uncontrolled proximal complement enables C3-mediated extravascular hemolysis. Linear correlation between sC5b-9 or Bb and LDH was not observed, even if spikes of sC5b-9 were observed in concomitance with BTH (as demonstrated by rise of LDH). In contrast, the pattern of these complement biomarkers was quite different in patients receiving proximal complement inhibitors, consistent with their capability of intercepting upstream complement activation. On danicopan monotherapy, both Bb (1.874±0.739 µg/mL) and sC5b-9 (695±225 ng/mL) were lower as compared with pre-treatment values, and C3d deposition on erythrocytes was not detectable. Similarly, on iptacopan monotherapy, both Bb (1.815±1.215 µg/mL) and sC5b-9 (557±475 ng/mL) were lower as compared to baseline values, and C3d deposition on erythrocytes became undetectable. When Bb and sC5b-9 were correlated with LDH looking to all aggregate data, we could not find any linear correlation; thus, when tracked in condition of complete complement inhibition, these biomarkers could not predict BTH. Nevertheless, fluctuations and spikes of Bb or sC5b-9 were seen, and even if they were always associated with LDH increase, symptomatic clinical BTH was observed just occasionally, demonstrating that these biomarkers are useful to track subtle, transient leakages of complement inhibition. Conclusions Systematic investigation of biomarkers of complement terminal, alternative and classical pathways in PNH patients proves that proximal complement inhibitors disable also the terminal complement, eventually leading to prevention of both intravascular and extravascular hemolysis. Since Bb and sC5b-9 are significantly reduced most of the time, they fail in tracking clinically meaningful chronic residual intravascular hemolysis. Nevertheless, Bb and sC5b-9 are elevated in case of in case of acute hemolysis, confirming transient loss of therapeutic inhibition at time of BTH. Since subtle fluctuations of Bb and sC5b-9 can be seen also in absence of clinically meaningful hemolysis, they track low-level residual in vivo complement activation, which may help in understanding the pharmacodynamics of novel complement inhibitors and how to best use them.

Trial in Progress: An Open-Label, Phase 2 Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Efficacy of KP104 in Complement Inhibitor-Naïve Subjects with Paroxysmal Nocturnal Hemoglobinuria

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a life-threatening disease characterized by destruction of red blood cells by the complement system, leading to pathologies such as anemia and thrombosis. Currently approved complement inhibitors target C5 which addresses primarily intravascular hemolysis (IVH). However, many treated patients are still anemic and transfusion dependent since C5 inhibitors cannot treat extravascular hemolysis (EVH), which is driven by the alternative pathway (AP). C3 inhibitors need frequent administration, high dosage, and are associated with breakthrough hemolysis (BTH) (Hillmen, 2021; Rother, 2007; Stern, 2019; Rosario, 2022). Thus, the treatment of PNH still remains a challenge with significant unmet medical needs to develop more efficacious and convenient complement drugs. KP104 is a bi-functional complement inhibitor that can inhibit both C5 and C3 convertase activities and thereby achieve high potency in treating complement mediated pathologies. KP104 is an engineered anti-C5 immunoglobulin G4 monoclonal antibody (mAb) fused with the N-terminal 5 short consensus repeats of human factor H (a potent AP inhibitor) and engineered to extend serum half-life. KP104 was generally well tolerated and safe in the First-in-Human (FIH), healthy volunteer Phase 1 trial (n=66). PD data from this FIH study also support the dual mechanisms of KP104 inhibiting both AP and terminal pathway (TP). In addition, an extended half-life for KP104 has been observed in healthy volunteers, compared to other approved bispecific/fusion proteins on the market. Details of the FIH study will be published at another major conference (Wabinitz, 2022). KP104 is being developed for multiple diseases with complement cascade dysregulation, with PNH being the first indication to be investigated. Study Design and Methods: This is an open-label, 2-part, Phase 2 study to evaluate safety, tolerability, PK, PD, and efficacy of KP104 in complement inhibitor-naïve subjects with PNH (NCT05476887). Approximately 35 subjects with PNH are planned to be enrolled, including up to 18 in the dose-ranging Part 1, and up to 17 in the proof-of-concept (POC) Part 2. The primary objectives of Part 1 are to assess safety and tolerability and estimate optimal biologic dose (OBD) and regimen of KP104 in complement inhibitor-naïve subjects with PNH. Part 1 will include up to 3 cohorts of 3 to 6 subjects/cohort dosed for 12 weeks (Figure 1). When the third subject in the last cohort of Part 1 completes 4 weeks of treatment, a KP104 OBD will be estimated for evaluation in Part 2. Part 2 is to confirm POC by studying the KP104 OBD in 1 cohort of complement inhibitor-naïve subjects with PNH (Figure 1). The primary efficacy endpoint is the proportion of subjects with a ≥2 g/dL increase in hemoglobin from baseline to the end of the treatment period, with the absence of transfusion through the treatment period. The percent of subjects showing an increase from baseline in hemoglobin of ≥2 g/dL at the end of the treatment period will be compared to a 15% reference rate using an exact binomial one-sample test. The sample size was calculated to achieve approximately 90% power with 0.025 type 1 error rate (one-sided). In summary, KP104, through effective inhibition of both AP and TP complement pathways, may achieve high potency and address IVH, EVH, and BTH for treating subjects with PNH. Hillmen P, Szer J, et al. 2021. Pegcetacoplan versus eculizumab in paroxysmal nocturnal hemoglobinuria. N Engl J Med 384:1028-1037. Rosario N, Lucio L. 2022. Breakthrough Hemolysis in PNH with Proximal or Terminal Complement Inhibition. N Engl J Med 387(2):160-166. Rother, R.P., et al. 2007. Discovery and development of the complement inhibitor eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria. Nat Biotechnol 25:1256-1264. Stern, R.M., and Connell, N.T. 2019. Ravulizumab: a novel C5 inhibitor for the treatment of paroxysmal nocturnal hemoglobinuria. Ther Adv Hematol 10:2040620719874728. Wabinitz, P., et al. 2022. SYNERGY-1: A Phase 1, first-in-human, randomized, double-blind, placebo-controlled safety, tolerability, immunogenicity, PK and PD study of KP104 in escalating single and multiple doses. ASN abstract. Under review. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Terminal Complement Inhibition and Control of Hemolysis in Paroxysmal Nocturnal Hemoglobinuria Following Switching from High-Dose Eculizumab to Ravulizumab: An Interim Analysis

Background: Intravenous (IV) complement component 5 (C5) inhibitors, eculizumab and ravulizumab, are the current standards of care in patients with paroxysmal nocturnal hemoglobinuria (PNH), a rare chronic blood disorder characterized by terminal complement activation, intravascular hemolysis (IVH), thrombotic events and organ damage. Ravulizumab is a second-generation analog of eculizumab with substitutions of four amino acids in the chemical backbone. This design enables ravulizumab to provide the same clinical benefit as eculizumab in patients with PNH at a longer dosing interval (every 8 weeks [q8w] vs every 2 weeks [q2w]). Approximately 10-15% of patients with PNH who receive the approved, fixed eculizumab dose (900 mg q2w) experience insufficient inhibition of IVH, as characterized by breakthrough hemolysis (BTH) towards the end of the dosing interval. In such patients, increasing the eculizumab dose (to > 900 mg q2w) can be effective. However, currently there are no recommendations or clinical trial data regarding the impact of switching these patients to ravulizumab. Aim: To assess the safety of switching from high-dose eculizumab to approved, weight-based ravulizumab dosing in patients with PNH. Methods: Study 401 (NCT04320602) is an ongoing, phase 4, single-arm, multicenter trial designed to investigate the impact of switching treatment from fixed, high-dose IV eculizumab (1200 mg q2w) to weight-based IV ravulizumab q8w in adult (≥ 18 years of age; N = 18) patients with PNH. Prior to (≥ 3 months) screening, patients receive high-dose IV eculizumab (1200 mg q2w); patients continue to receive this throughout the 3-month screening period before switching to weight-based IV ravulizumab. Patients receive loading and maintenance ravulizumab doses, as per the approved prescribing information (Alexion, AstraZeneca Rare Disease. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/761108s000lbl.pdf). The primary endpoint is the proportion of patients who experience serum free C5-associated BTH (defined as ≥ 1 new or worsening symptom or sign of IVH [fatigue, hemoglobinuria, abdominal pain, dyspnea, anemia, major adverse vascular events, dysphagia or erectile dysfunction] with lactate dehydrogenase [LDH] levels ≥ 2 × upper limit of normal [ULN] and free C5 concentrations ≥ 0.5 μg/mL). Other endpoints include change in free C5 concentrations and LDH levels over time, and the proportion of patients with treatment-emergent adverse events (TEAEs) and treatment-emergent serious adverse events (TESAEs). This interim analysis describes data up to day 183 of follow-up. Results: Data for 10/18 enrolled patients (55.6%) were available. Baseline demographics and clinical characteristics are described in Table 1. From baseline to day 183, no instances of free C5-associated BTH were reported and free C5 concentrations remained below 0.5 μg/mL for all patients at all study timepoints (Figure 1). Similarly, from baseline to day 183, LDH levels remained ≤ 1.5 × ULN in all patients. Up to day 183, 7/10 patients (70.0%) reported TEAEs that were mild (n = 3, 30.0%) or moderate (n = 4, 40.0%) in severity. There were no instances of meningococcal infection, TESAEs and none of the documented TEAEs led to death or study withdrawal. BTH was reported in one patient (local laboratory-reported LDH level = 492.0 U/L; local normal range: 120.0-246.0 U/L), this was deemed to be vaccine-related as both coronavirus disease 2019 and influenza vaccinations were administered the day prior to the event. However, no elevated free C5 level was detected in the earliest available sample (0.11 μg/mL, collected four days after the event) and the patient continued ravulizumab treatment. Conclusions: Results of this interim analysis showed that, based on a small sample of patients with PNH (N = 10), switching treatment from high-dose IV eculizumab (1200 mg q2w) to standard, weight-based IV ravulizumab q8w was well tolerated, with minimal changes in laboratory measures associated with PNH symptoms. Up to day 183, no free C5-associated BTH was reported and the safety profile of ravulizumab was considered comparable to previously published studies, with no instances of meningococcal infection or TESAEs reported. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pediatric-Specific Patterns of Clonal Evolution Arising from Acquired Aplastic Anemia

Introduction Acquired aplastic anemia (aAA) occurs in both children and adults, though pathophysiology and clinical outcomes differ significantly by age. While clinical testing for paroxysmal nocturnal hemoglobinuria (PNH) clones is routine, targeted next generation sequencing (NGS) for myelodysplastic syndrome (MDS) associated variants has only recently been implemented. Furthermore, single nucleotide polymorphism array (SNP-A) assessing for copy neutral loss of heterozygosity in the human leukocyte antigen (HLA) region on chromosome 6p (6p CN-LOH) and HLA NGS assessing for allele specific loss of function (LoF) mutations, which together are seen in up to 25% of aAA cases, are only now being considered for clinical use. Recent studies have reported on the frequency and overlap of these 3 types of clonal evolution (PNH, MDS-associated, HLA-targeting) in adult aAA cohorts, but none focus specifically on pediatric patients, whose MDS-associated clonal evolution patterns are distinct. Delineating patterns of clonal hematopoiesis in pediatric aAA to determine whether evolution driven by immune escape (PNH and HLA loss) affects likelihood of MDS development is critical for personalizing therapeutic options. Thus, we aimed to describe the frequency, clinical significance, and overlap of clonal evolution including PNH, HLA loss, and MDS-associated gene mutations in a pediatric cohort of aAA patients. Methods This study identified 85 pediatric aAA patients treated at Children's Hospital of Philadelphia (CHOP) and enrolled on the IRB-approved CHOP/Penn BMF Registry and Repository in whom clinical testing for all patterns of clonal hematopoiesis was available or could be performed with biorepository samples. PNH flow cytometry was performed clinically in all cases; subjects with PNH > 0.05% in the granulocyte fraction were considered as having a PNH clone. Peripheral blood and bone marrow samples were used for SNP-A, HLA-NGS, and an institutional somatic mutation NGS panel for hematological malignancies encompassing 118 genes. Descriptive and contingency statistical analyses along with Fisher's Exact Test were performed using SAS (Cary, NC). Results Demographic composition of the 85 pediatric subjects with aAA included a median age of 10.7 years (1.7-20.8), male/female ratio of 59%/41%, and a representative race/ethnicity distribution (Table 1). In total, 66% displayed at least one clonal event. As expected, PNH clones were most common, present in 45% (38/85) of the cohort. An additional 16 (19%) exhibited acquired HLA loss by 6p CN-LOH (n=6), allele specific LoF mutations (n=6), or both (n=4). Fifteen (18%) had clonal hematopoiesis associated with MDS, of whom 3 had cytogenetic lesions that progressed to clinical MDS (3.5%), and 12 developed no morphologic features of MDS but demonstrated a total of 14 mutations in MDS-associated genes (BCOR/BCORL1 n=6, KMT2C/KMT2D n=3, RUNX1 n=1, ASXL1 n=1, SRSF2 n=1, PRPF8 n=1, CALR n=1). Critically, pediatric subjects with aAA who developed HLA loss did not develop MDS-associated mutations, with no patient demonstrating both subtypes of clonal events (Figure 1). In contrast, PNH and MDS-associated clonal events overlapped in 11% of the overall cohort. In total, 60% of patients with MDS-associated clonal hematopoiesis also possessed PNH clones, and 23% of patients with detectable PNH clones demonstrated at least one MDS-associated clonal event. Only 3.53% (n=3) of the cohort demonstrated both PNH and HLA loss, and PNH clone size was < 1% in all 3 patients. Furthermore, patients with HLA loss were significantly less likely to have PNH clones than those without HLA somatic alterations (19% vs 51%, p = 0.026). Correlations between patterns of clonal hematopoiesis and clinical outcomes will be presented. Concalusions Pediatric aAA patients treated with IST are at risk for developing MDS and hemolytic PNH. Presence and evolution of clonal hematopoiesis influenced decisions to pursue IST versus alternative donor transplant. Importantly, our study demonstrates that occurrence of clonal hematopoiesis by HLA loss does not increase and may even decrease the risk of developing MDS-associated or PNH clones. This finding strongly suggests that treatment decisions for aAA patients whose only clonal event is HLA loss need not be considered distinctly from patients with no clonal changes. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Immune Checkpoint Molecules Regulate Paroxysmal Nocturnal Hemoglobinuria Clonal Evolution

In paroxysmal nocturnal hemoglobinuria (PNH), the acquisition of somatic PIGA mutations provides a selection advantage to hematopoietic stem cells from aplastic anemia (AA) immune attack. In addition to this immune evasion mechanism, HLA mutations, deletions, and somatic UPD involving 6p21 locus have been also described in AA, all of which implicated in such adaptive clonal escape. It is well-known that blood cells derived from a PIGA-mutant clone lack membrane-bound complement regulators (e.g., CD55, CD59) and exhibit an increased vulnerability to complement attack. Nevertheless, PIGA-mutant cells may still be susceptible targets for AA T cell-mediated immune attack. In conjunction with mutational analysis, HLA protein expression may be investigated by flow cytometry to identify a haploinsufficient (clonal) vs. possible adaptive down-modulation. Indeed, the absence of these otherwise constitutionally expressed proteins represents an excellent marker of clonality. Additionally, in an attempt to further hinder the creation of a successful immunological synapsis, other mechanisms, including modulation of immune checkpoints expression, may be also involved in such AA/PNH intertwine. Whether these immune escape mechanisms are convergent or instead represent alternative pathways is a subject of intense research. Here, we comprehensively explore the dynamics governing PNH immune ontogenesis by combining HLA/PIGA genomics and flow cytometric measurements of HLA (A, B, C, DQ, DR, DP) and the immune checkpoint B7/CD28H family (PD1, PDL1, PDL2, VISTA, B7-H6, HHLA2, CD28H), stimulatory (GITR, CD30L) and inhibitory immune checkpoints (CD47) in CD45+CD15+CD59+ and CD59- fractions. A deep targeted sequencing panel covering HLA classical loci along with an in-house developed pipeline was also applied to assess fine HLA aberrations (mutational and copy number events), whereas multi-amplicon deep sequencing was deployed to identify PIGA mutational status. A total of 27 PNH patients classified as fully blown hemolytic PNH (n=15) or PNH/AA overlap (n=12) were included in this study with additional 4 healthy controls (HC). Overall, 41% of our patients harboured concomitant myeloid clones (most common hits were in DNMT3A, TET2, ASXL1, BCOR), while 58% of cases carried somatic HLA alterations, involving allelic losses or mutations. The latter were nonsense (33%), missense (11%), or 5’ or 3’ UTR (56%) hits with a median VAF of 11% (3-95%). Somatic lesions (including losses) were found in HLA-A (10%), B (30%), DQA1 (10%), or DQB1 (50%) loci. Since HLA aberrations may constitute the extreme pole of immune evasion and a marker of enhanced immune selection, we performed sorting/sequencing experiments on CD59+vs CD59- cells. A similar distribution and clonal burden of HLA-mutant subclones was found between the 2 fractions, indicating that PNH cells do not provide absolute immune privilege.1 Next, we compared the expression of HLA and other immunomodulatory molecules across HC, CD59+ cells from PNH patients and their corresponding CD59- cells (GPI+ and GPI-, respectively). Using MFI as a readout, GPI- cells showed similar expression levels of HLA-DP, -DR, PDL2, HHLA2 and GITR as compared to HC cells, while these molecules were significantly 1.5 to 5-fold upregulated on corresponding GPI+ cells consistent with their trigger/target function. This conclusion was also supported by the higher levels of CD28H found on GPI+ cells vs. GPI-(median MFI, 13.3 vs. 6.0; p<0.0001). Of note is that GPI- cells exhibited lower levels of HLA-DQ (0 vs. 7.0, p=0.01), B7H6 (0 vs. 39, p<0.0001) and CD30L (0 vs. 41, p <0.0001) vs. HC cells and upregulation of VISTA (460 vs. 227, p=0.006), suggesting that PNH clones may exhibit additional (to PNH phenotype) immune deterrence pathways. HLA alterations resulted in downregulation of HLA-DQ (0 vs. 29, p=.03), -DR (20 vs. 136, p=.03), B7H6 (0 vs. 45, p=.02), and CD30L (7.5 vs. 52, p=.02), as well as upregulation of HLA-B (2671 vs. 1909, p=.03) and VISTA (561 vs. 291, p=.02) in GPI- vs. GPI+, while no difference was noted in HLAWT cases. In conclusion, differential expression of immunomodulatory molecules on PNH vs. residual phenotypically normal cells in PNH patients and HC highlights various stimulatory and immune escape mechanisms operating in this disease. Understanding these processes may enable the identification of therapeutically relevant immune pathways.

Pregnancy in Paroxysmal Nocturnal Hemoglobinuria - a Systematic Review

Background Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, clonal disorder of hematopoietic stem cells, characterized by complement-mediated intravascular hemolysis, thrombosis, and bone marrow failure. Pregnancy exacerbates the clinical features of PNH, increasing maternal and fetal morbidity and mortality. Pregnancy in patients with PNH has traditionally been discouraged. Terminal complement inhibition with eculizumab gained regulatory approval in 2007 and has revolutionized the management of PNH. Limited data suggest that eculizumab is also safe and efficacious during pregnancy. Owing to the rarity of PNH and the inability to conduct randomized controlled trials on this population, most reports are small case series, with even the largest retrospective studies including well below 100 patients. We therefore present the first comprehensive systematic review and meta-analysis of outcomes in 190 pregnancies from 135 women with PNH. We compare pregnancy complications between those receiving eculizumab and those not, since complement blockade is not universally available. For the first time we demonstrate that eculizumab is associated with a lower risk of fetal loss. Methods The PubMed (Medline) database was searched for studies reporting primary data on pregnancy outcomes in the context of classical hemolytic PNH, diagnosed through flow cytometry, acid Ham's or sucrose lysis (Figure 1). Women with evidence of recurrent hemolytic episodes including serum lactate dehydrogenase >1.5 times the upper limit of normal, and typical PNH symptoms were included. We excluded papers where there was insufficient information for meaningful downstream analysis, or where cases were duplicated elsewhere in the literature. The search was restricted to English language papers. Two reviewers independently screened articles for inclusion with a third opinion sought where there was disagreement. References of included papers and review articles were screened to identify further papers. Thirty-six papers published between 1968 to 2021 were selected for inclusion. The majority were small case series or single case studies. There were two larger retrospective studies reporting on 45 and 75 pregnancies respectively. There was one prospective study (n=15 pregnancies). Results Eculizumab was used in 130 pregnancies. No maternal deaths were reported in patients on eculizumab. One woman who had never received eculizumab died at 12 weeks postpartum from intra-abdominal sepsis following a severe episode of acalculous cholecystitis. A higher rate of fetal survival was observed in pregnancies where eculizumab was used (82%) than in pregnancies when it was not (69%) (Table 1). Thrombosis occurred at a higher rate than in the healthy pregnant population but did not significantly differ in incidence between treatment groups (Table 1). The incidence of pre-eclampsia was high in this population. There was a trend towards a reduced risk of pre-eclampsia and infection in eculizumab pregnancies, but this did not reach statistical significance (Table 1). No Neisserial infections were observed in patients treated with eculizumab. The rate of spontaneous miscarriage (<24 weeks') was nearly twice as high in women who had not received eculizumab (18.6%) compared to those who received it (9.7%). The rate of intrauterine death did not significantly differ between treatment groups (Table 1). Fetal structural anomalies occurred in three cases, none of which had been exposed to eculizumab, supporting the notion that the drug does not have a teratogenic effect. Intrauterine growth restriction (IUGR) occurred in just over 8% of pregnancies that progressed beyond 20 weeks and did not differ between treatment groups (Table 1). IUGR was associated with pre-eclampsia in eight cases (61%). 148 pregnancies progressed to delivery, the majority by vaginal delivery. Premature birth (<37 weeks' gestation) was observed in 32% of eculizumab pregnancies and 44% of non-eculizumab pregnancies. Premature delivery was usually iatrogenic due to maternal or fetal complications, with spontaneous premature labor in only eight cases (15%). Conclusion Eculizumab appears to be safe and provide a benefit in pregnancy in PNH. There were less premature births and spontaneous miscarriages and greater fetal survival when eculizumab was given. A tendency to fewer cases of pre-eclampsia and maternal infections was also seen. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

How we (will) treat PNH?

Clinical signs arising from intravascular hemolysis, hemolysis-related transfusions and thrombosis are indications for treatment initiation in paroxysmal nocturnal hemoglobinuria (PNH), whereas clone size per se is not. Eculizumab prevents intravascular hemolysis and reduces significantly thromboembolic risk resulting in a five-year overall survival of >90%. Hemoglobin value, LDH and reticulocyte count are used to define treatment response. Residual intravascular hemolysis is mainly caused by an incomplete C5 blockage and can lead to continuous low‐grade hemolysis or transient breakthrough hemolysis episodes in 10-15% of PNH patients. Additional complement‐amplifying conditions such as infections, surgery or pregnancy may overcome efficient therapeutic levels of Eculizumab and therefore require dose adjustments. C3‐mediated extra‐vascular hemolysis represents the main reason for residual anemia during anti‐C5 treatment. Patients with an inherited C5-variant lack response to Eculizumab and have been directed (in past) towards allogeneic HSCT. Transplantation has an overall mortality of up to 30%, with a higher risk in patients with previous thrombosis. A plethora of novel therapeutic agents are reported to impact on both; residual intravascular hemolysis and C3‐mediated extra‐vascular hemolysis. The new C5 inhibitor Ravalizumab with an eight‐week i.v. dosing interval showed non-inferiority to Eculizumab. Crovalimab, binding on the single missense C5 heterozygous mutation is injected s.c. monthly; two large phase III trials are ongoing as add on- and mono-therapy. Others, such as Pozelimab, injected subcutaneously on a weekly basis after an initial IV loading dose or Tesidolumab are still under current investigation. Currently investigated proximal inhibitors are acting towards: (i) the C3 complement; (ii) complement factor D or (iii) the complement factor B. They are aiming in particular to prevent C3‐mediated extra‐vascular hemolysis. Pegcetacoplan is a PEGylated version of compstatin which binds to C3 and is injected s.c. in monotherapy 4 weeks after initial concomitant therapy with Eculizumab. In a recent phase III trial, pegcetacoplan showed superiority to eculizumab in hemoglobin change from baseline and is now approved by the FDA for patients with PNH who are either treatment‐naive or switching from anti‐C5 monoclonal antibodies. Danicopan is an oral first‐in‐class factor D complement alternative pathway inhibitor and decreased significantly transfusion requirement, as shown in a phase II trial (phase III ongoing). BCX9930, another FD inhibitor in early development is given orally and demonstrated initial clinical efficacy both as add‐on therapy in patients with inadequate response to eculizumab as well as in monotherapy in treatment‐naive patients. In conclusion, novel proximal and distal complement inhibitors with different application modalities, in part as add-on or monotherapy seem to improve significantly intra- and extra‐vascular hemolysis in PNH, resulting in a better hematological benefit. Before choosing specific treatment, hematologists have to assess hemolysis, thrombosis and patients‘ bone marrow function. Future studies will help to explore long-term efficacy and safety of these novel agents.

Breakthrough haemolysis in paroxysmal nocturnal haemoglobinuria after COVID-19 infection and COVID vaccination: what is worse?

Breakthrough haemolysis in paroxysmal nocturnal haemoglobinuria after COVID-19 infection and COVID vaccination: what is worse?

Clonal Evolution of Aplastic Anemia: A Brief Literature Review and a Case Report

Aplastic anemia (AA) is a non-neoplastic hematological disease closely associated with bone marrow failure which is typical of paroxysmal nocturnal hemoglobinuria (PNH) and myelodysplastic syndrome (MDS). The PNH clones can be detected in more than a half of AA patients at onset of the disease, and there is a probability for AA/PNH co-variants to progress to classic hemolytic PNH. At the same time, the AA patients treated by immunosuppressive therapy undergo the risk of disease transformation to MDS and acute myeloid leukemia. Currently known risk factors and possible precursors of such transformation are considered in the brief literature review. In addition to that, the paper provides a case report of AA/PNH transformation to MDS during complete AA remission after immunosuppressive therapy combined with a successful haploidentical transplantation of hematopoietic stem cells.

Paroxysmal Nocturnal Hemoglobinuria in the Context of a Myeloproliferative Neoplasm: A Case Report and Review of the Literature

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by intravascular hemolytic anemia and thrombosis and is notoriously associated with aplastic anemia and myelodysplastic syndromes. Rarer associations include myeloproliferative neoplasms (MPNs), which are also burdened by increased thrombotic tendency. The therapeutic management of this rare combination has not been defined so far. Here, we describe a 62-year-old man who developed a highly hemolytic PNH more than 10 years after the diagnosis of MPN. The patient started eculizumab, obtaining good control of intravascular hemolysis but without amelioration of transfusion-dependent anemia. Moreover, we performed a review of the literature regarding the clinical and pathogenetic significance of the association of PNH and MPN. The prevalence of PNH clones in MPN patients is about 10%, mostly in association with JAK2V617F-positive myelofibrosis. Thrombotic events were a common clinical presentation (35% of subjects), sometimes refractory to combined treatment with cytoreductive agents, anticoagulants, and complement inhibitors. The latter showed only partial effectiveness in controlling hemolytic anemia and, due to the paucity of data, should be taken in consideration after a careful risk/benefit evaluation in this peculiar setting.