anti-C5 Monoclonal Antibody Research Articles

Two cases of typical HUS in adults treated with an anti-C5 monoclonal antibody: a new perspective?

Hemolytic uremic syndrome (HUS) is a rare clinical entity, especially in adults. In its typical form the causative factor that triggers the cascade of immunologic and inflammatory events is a Shiga toxin-producing pathogen, found in the patient's stool. Renal and neurologic involvement usually prevails and requires immediatecare. Regarding thispotentially life-threatening condition, little is known and the mainstay is supportive care. However, some interesting evidence has come up about the use of eculizumab, an anti-C5 monoclonal antibody, mainly in pediatric patients with typical HUS. Herein, we present two cases with typical HUS caused by two different strains of Escherichia coli (Shiga toxin-producing enterohemorrhagic and enteropathogenic) who were both treated effectively with anti-C5 monoclonal antibodies (eculizumab and ravulizumab).

Anti-C5 monoclonal antibody treatment showing pathological resolution of complement-mediated atypical hemolytic uremic syndrome: a case report

BackgroundNo reports have shown histological changes before and after anti-C5 monoclonal antibody treatment in patients with atypical hemolytic uremic syndrome (aHUS). Here, we report a rare case of complement-mediated aHUS with a complement factor H (CFH) mutation and anti-CFH antibodies who underwent multiple kidney biopsies.Case presentationA 53-year-old woman developed aHUS with CFH gene mutation [c.3572C > T (p. Ser1191 Leu)] and anti-CFH antibodies. Her father had succumbed to acute kidney injury (AKI) in his 30 s. She exhibited AKI, thrombocytopenia, and hemolytic anemia with schistocytes. After improving the platelet count with one session of plasma exchange, a kidney biopsy was performed one month after the onset of symptoms. Blood vessel thrombosis, obvious endothelial swelling, endocapillary hypercellularity, and subendothelial exudative lesions in the glomeruli and arterioles were detected. Anti-C5 monoclonal antibody treatment with eculizumab immediately improved disease activity. A second biopsy 3 months later revealed marked improvement of endothelial injuries with residual membrane double contours and exudative lesions. A third biopsy at 17 months after gradual improvement of kidney function showed a further decrease of double contours along with alterations of the exudative lesions to fibrous intimal thickening.ConclusionsThis is the first report showing the pathophysiology of aHUS in the kidneys and the efficacy of anti-C5 monoclonal antibody treatment by presenting serial kidney pathological features before and after anti-C5 monoclonal antibody treatment. Since her CFH mutation was considered the most important pathological condition, treatment centered on eculizumab was administered, resulting in a good long-term prognosis. In addition, kidney pathological resolution in aHUS occurred over 1 year after anti-C5 monoclonal antibody treatment.

Ravulizumab facilitates reduced burden of vascular access, a major benefit in paediatric atypical haemolytic uraemic syndrome.

Atypical haemolytic uraemic syndrome (aHUS) is a rare thrombotic microangiopathy resulting from dysregulation of the alternative complement pathway, leading to multi-organ dysfunction and chronic kidney disease. Eculizumab is an anti-C5 monoclonal antibody therapy that has significantly improved aHUS disease control and patient outcomes, however it requires fortnightly intravenous dosing. This often necessitates long term central access and a high hospital attendance burden. Ravulizumab is a novel, next-generation anti-C5 monoclonal antibody engineered from eculizumab to reduce endosomal degradation of the antibody, increasing the dosing interval up to 8 weeks. In this retrospective case series we present the transition of three children with aHUS from eculizumab to ravulizumab from a single tertiary paediatric nephrology service. All patients underwent genomic and immunological work up for aHUS, with no cause found. After stabilisation with eculizumab, two patients developed macrovascular thrombotic complications associated with indwelling central vascular catheters, ultimately leading to central access failure. All patients were transitioned from eculizumab to ravulizumab without relapse of aHUS. One patient successfully underwent deceased donor kidney transplantation with ravulizumab for complement inhibition. All patients have transitioned to peripheral access for infusions given the reduced frequency of dosing, maintaining good control of aHUS for 2-4 years. Ravulizumab permits sufficiently reduced frequency of infusion to allow for administration by peripheral cannulation - removing the risks of long term central vascular access often required to deliver eculizumab to paediatric patients.

Antiphospholipid Patients Admitted in the Intensive Care Unit: What Must The Rheumatologist Know?

Antiphospholipid syndrome (APS) is a rare systemic autoimmune disorder that can escalate into a 'thrombotic storm' called the catastrophic antiphospholipid syndrome (CAPS), frequently requiring ICU admission for multiple organ failure. This review aims to offer insight and recent evidence on critically-ill APS patients. The CAPS classification criteria define this condition as the involvement of at least three organs/systems/tissues within less than a week, caused by small vessel thrombosis, in patients with elevated antiphospholipid antibodies levels. These criteria do not encompass the full spectrum of critically-ill thrombotic APS patients and they need to be cautiously used for the bedside diagnosis of CAPS. Thrombocytopenia is the laboratory hallmark of CAPS, sometimes dropping below 20G/L, but a complete thrombotic microangiopathy pattern is infrequent. Anticoagulation is the pivotal treatment for APS and CAPS, associated with improved outcome. Triple therapy - the combination of anticoagulation, high-dose corticosteroids, and either plasma exchange or intravenous immunoglobulins - remains the standard treatment for CAPS patients. Eculizumab, an anti-C5 monoclonal antibody, may be useful in refractory patients. Despite significant progress, CAPS mortality rate remains high. Its diagnosis and management are complex, requiring a close multidisciplinary cross talk between APS specialists and intensivists.

Complement inhibition in paroxysmal nocturnal hemoglobinuria: From biology to therapy.

Complement inhibitors are the mainstay of paroxysmal nocturnal hemoglobinuria (PNH) treatment. The anti-C5 monoclonal antibody eculizumab was the first treatment to improve hemolysis, thrombotic risk, and survival in PNH although at the price of a life-long intravenous fortnightly drug. Additionally, suboptimal response may occur in up to 2/3 of patients with persistent anemia due to incomplete control of intravascular hemolysis, development of upstream C3-mediated extravascular hemolysis (EVH), or concomitant bone marrow failure. Ravulizumab, a longer half-life anti-C5 developed from eculizumab, administered every 8 weeks, improved patient convenience, and reduced pharmacokinetic breakthrough hemolysis (BTH) by establishing more stable anti-C5 concentrations. More recently, several other anti-C5 compounds (crovalimab, pozelimab, tesidolumab, cemdisiran, zilucoplan, and coversin) are on study in clinical trials. Upstream inhibition of complement cascade was also explored with the anti-C3 pegcetacoplan, and with the alternative pathway inhibitors iptacopan (anti-factor B) and danicopan (anti-factor D). These drugs efficiently target EVH and are able to improve anemia and transfusion need in suboptimal responders to anti-C5. The route and schedule of administration (twice weekly subcutaneously for pegcetacoplan and twice or thrice oral daily dosing for iptacopan and danicopan, respectively) are very convenient but pose novel issues regarding adherence. Additionally, both anti-C5 and upstream inhibitors do not resolve the unmet need of pharmacodynamic BTH events due to complement amplifying conditions such as infections, traumas, and surgery. In this review, we will recapitulate PNH physiopathology, clinical presentation, and diagnosis and describe available and developing drugs that will lead to a precision medicine approach for this rare though heterogenous disease.

Cost-Utility Analysis Comparing Pegcetacoplan to Anti-C5 Monoclonal Antibodies in the Treatment of Paroxysmal Nocturnal Hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria is a rare, acquired disease characterized by hemolytic episodes and associated with significant clinical burden. The introduction of C5 inhibitory monoclonal antibodies (C5i) represented a major breakthrough in PNH treatment, effectively reducing intravascular hemolysis (IVH) but showing limited impact on extravascular hemolysis (EVH). In 2021, the C3 inhibitor pegcetacoplan was approved by EMA and recently reimbursed in Italy, which also has the advantages in the reduction of both IVH and EVH, increasing hemoglobin values and simultaneously improving the quality of life and fatigue of patients. A cost-utility analysis was developed to compare pegcetacoplan to C5i (eculizumab and ravulizumab) in the PNH population who remain anemic after treatment with C5i for at least 3 months. The analysis employed a Markov model with a 5-year time horizon whereby patients can transition among 3 PNH health states, adopting the perspective of the Italian NHS. Efficacy data were sourced from the PEGASUS study, with drug prices reflecting ex-factory costs. Additionally, costs associated with resource utilization, adverse events, and complications were estimated based on outpatient and hospital care rates, excluding indirect expenses. Utility and disutility values related to transfusions were also considered, with pegcetacoplan allowing for dose escalation. The cumulative cost of treatment per individual patient at 5 years was estimated to be €1,483,454 for pegcetacoplan, €1,585,763 for eculizumab, and €1,574,826 for ravulizumab. Pegcetacoplan demonstrated a superior increase in quality-adjusted life years (QALYs) compared to both eculizumab (0.51 increase) and ravulizumab (0.27 increase). Furthermore, pegcetacoplan showed a reduction in complication management costs (€22,891 less compared to eculizumab and €22,611 less compared to ravulizumab) and lower transfusion-related expenses (€14,147 less than both C5i treatments). Pegcetacoplan emerged as the dominant strategy in this analysis, being more effective, less expensive and improves quality of life in the analyzed population affected by PNH.

Paroxysmal Nocturnal Hemoglobinuria: Current Management, Unmet Needs, and Recommendations.

Paroxysmal nocturnal hemoglobinuria (PNH) is an ultra-rare, acquired clonal abnormality, which renders hematopoietic cells exquisitely sensitive to complement-mediated destruction. Classical features of PNH include intravascular hemolytic anemia, increased thrombotic risk, and manifestations related to end-organ damage (eg fatigue, chest pain, dyspnea, renal failure, and pulmonary hypertension). With supportive care alone, mortality rate of patients with PNH is approximately 35%. The anti-C5 monoclonal antibody, eculizumab, was the first targeted therapy approved for PNH, and led to improved hemoglobin, quality of life, reduced transfusion need, reduced thrombosis, and greater overall survival. More recently, therapeutics such as longer acting anti-C5 (ravulizumab) and anti-C3 (pegcetacoplan) medications have been approved, along with other novel therapeutics in late-stage clinical trials. Biosimilars of eculizumab are also now available. Proximal inhibitors (against C3, factor B, and factor D) have shown significant improvements in hemoglobin and transfusion-avoidance in patients who remain anemic despite C5 inhibition. Despite these novel therapies, some unmet challenges remain, including management of breakthrough hemolysis, clinically significant iatrogenic extravascular hemolysis, optimal management in pregnancy, and infection risk mitigation as new targets in the complement system are blocked. In addition, the use of self-administered subcutaneous and oral therapies raises concerns around treatment adherence and the risks of uncontrolled terminal complement. Given the ultra-rare nature of PNH, development is underway of a centralized international registry to capture and analyze the data as they mature for various new therapies and characterize the clinical challenges related to PNH management.

A Case Report of a Patient with Paroxysmal Nocturnal Hemoglobinuria Treated with Pegcetacoplan Who Underwent Major Surgery

Paroxysmal Nocturnal Hemoglobinuria (PNH) is characterized by intravascular hemolysis, thrombosis and bone marrow failure. The appearance of the anti-C5 monoclonal antibody eculizumab revolutionized the treatment of PNH, controlling hemolysis and the incidence of thrombosis. However, some patients persist with anemia, due in part to extravascular C3-mediated hemolysis. More recently, the anti-C3 monoclonal antibody pegcetacoplan, which blocks the most proximal part of the complement cascade, has been marketed in Europe, achieving improvements in anemia in these patients. However, intercurrent infectious episodes or surgical interventions can trigger a hemolytic flare, so dose adjustments are necessary to prevent their occurrence. There is hardly any published information or established consensus on how to treat these patients. We present this case as an example of a successful treatment of a patient diagnosed with PNH under treatment with pegcetacoplan who has undergone major surgery. A 67 year-old man was diagnosed with aplastic anemia in 1997 and treated with immunosuppression (cyclosporine and oxytosone). In 2000, he presented his first intravascular hemolytic crisis with HPN clone detection. He presented several intravascular hemolytic crises for which he was treated with erythropoiesis-stimulating agents, corticosteroids and transfusions. In 2010, due to deterioration of renal function because of acute hemolysis episode, he started treatment with eculizumab. A reduction in the number of hemolytic crises was observed. However, he required an increase in the dose and frequency of administration of eculizumab due to pharmacokinetic breakthrough hemolysis. After one month of treatment, a positive direct coombs test appeared and presented anemia due to extravascular hemolysis, for which he again required treatment with corticosteroids on specific occasions. For this reason, in December 2022, he started treatment with pegcetacoplan at the usual dose of 1080 mg twice a week subcutaneously (sc). Prior to the start of pegcetacoplan, the patient had hemoglobin levels of 10.3 g/dL, hyperbilirubinemia of 3.2 mg/dL (indirect 2.6 mg/dL), consumed haptoglobin, elevated lactate dehydrogenase (LDH) of 281 U/L and reticulocytosis of 5-6%. Subsequently, since the beginning of pegcetacoplan, he presented clinical improvement, stable hemoglobin (12-13 g/dL) and normalization of reticulocytes, LDH and bilirubin levels. The haptoglobin has remained low until the present time. In June 2023, the patient underwent major surgery consisting of radical prostatectomy due to a benign prostatic hypertrophy. Suspecting that it might provoke a hemolytic crisis due to surgical stress, the dose of pegcetacoplan was increased as recommended by clinical experts to a dose of 1080 mg every 72 hours sc from one week prior to surgery until one week after. The procedure was carried out without incident and without an increase in hemolysis parameters. This is the first case report of a patient with PNH treated with pegcetacoplan undergoing major surgery in Spain. In this patient, the perioperative dose increase was successful in preventing the development of a hemolytic crisis.

Complement-mediated thrombotic microangiopathy treated with anticomplement protein 5 therapy, a retrospective study.

Complement-mediated thrombotic microangiopathy (CM-TMA), also called atypical hemolytic uremic syndrome (aHUS), is a difficult-to-diagnose rare disease that carries severe morbidity and mortality. Anti-C5 monoclonal antibodies (aC5-mab) are standard treatments, but large studies and long-term data are scarce. Here, we report our single institution experience to augment the knowledge of CM-TMA treated with aC5-mab therapy. We aimed to assess the short and long-term effects of aC5-mab in patients diagnosed with CM-TMA treated outside of a clinical trial. This was a retrospective study. We included all patients diagnosed with CM-TMA and treated with aC5-mab at our institution. There were no exclusion criteria. Endpoints included complete TMA response (CR) defined as normalization of hematological parameters and ≥25% improvement in serum creatinine (Cr) from baseline in patients with renal disease, relapse defined as losing the previously achieved CR, morbidity, adverse events, and survival. We found 28 patients with CM-TMA treated with aC5-mab. The median age was 50 years. Baseline laboratories: platelet counts 93 × 109 /L, hemoglobin 8.6 g/dL, lactate dehydrogenase 1326 U/L, serum Cr 4.7 mg/dL, and estimated glomerular filtration rate 19 mL/min. One individual was on renal replacement therapy (RRT) and 10 initiated RRT within 5 days of the first dose of aC5-mab. Genetic variants associated with CM-TMA included mutations in C3, CFB, CFH, CFHR1/3, CFI, and MCP. The mean duration of hospitalization was 24 days. The median time to initiation of aC5-mab was 10 days. Sixteen subjects received RRT. At the time of hospital discharge, 27 were alive, 14 remained on RRT, and 4 had a CR. At 6 months, 23 patients were alive, 18 continued aC5-mab, 8 remained on RRT, and 9 had a CR. At the last follow-up visit past 6 months, 20 were alive, 14 continued aC5-mab, 5 remained on RRT, 12 had a CR, and 1 was lost to follow-up. Our study provides real-world experience and insight into the long-term outcomes of CM-TMA treated with aC5-mab. Our findings validate that CM-TMA is an aggressive disease with significant morbidity and mortality, and confirm that aC5-mab is a relatively effective therapy for CM-TMA. Our study adds practical, real-world experience to the literature, but future research remains imperative.

Cold exposure induces vaso-occlusion and pain in sickle mice that depend on complement activation

AbstractVaso-occlusive pain episodes (VOE) cause severe pain in patients with sickle cell disease (SCD). Vaso-occlusive events promote ischemia/reperfusion pathobiology that activates complement. We hypothesized that complement activation is linked to VOE. We used cold to induce VOE in the Townes sickle homozygous for hemoglobin S (HbSS) mouse model and complement inhibitors to determine whether anaphylatoxin C5a mediates VOE. We used a dorsal skinfold chamber to measure microvascular stasis (vaso-occlusion) and von Frey filaments applied to the plantar surface of the hind paw to assess mechanical hyperalgesia in HbSS and control Townes mice homozygous for hemoglobin A (HbAA) mice after cold exposure at 10°C/50°F for 1 hour. Cold exposure induced more vaso-occlusion in nonhyperalgesic HbSS mice (33%) than in HbAA mice (11%) or HbSS mice left at room temperature (1%). Cold exposure also produced mechanical hyperalgesia as measured by paw withdrawal threshold in HbSS mice compared with that in HbAA mice or HbSS mice left at room temperature. Vaso-occlusion and hyperalgesia were associated with an increase in complement activation fragments Bb and C5a in plasma of HbSS mice after cold exposure. This was accompanied by an increase in proinflammatory NF-κB activation and VCAM-1 and ICAM-1 expression in the liver. Pretreatment of nonhyperalgesic HbSS mice before cold exposure with anti-C5 or anti-C5aR monoclonal antibodies (mAbs) decreased vaso-occlusion, mechanical hyperalgesia, complement activation, and liver inflammatory markers compared with pretreatment with control mAb. Anti-C5 or -C5aR mAb infusion also abrogated mechanical hyperalgesia in HbSS mice with ongoing hyperalgesia at baseline. These findings suggest that C5a promotes vaso-occlusion, pain, and inflammation during VOE and may play a role in chronic pain.

5612539 TRIAL IN PROGRESS: THE RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED PHASE 2A CROSSWALK-C TRIAL EVALUATING THE EFFICACY OF CROVALIMAB AS ADJUNCT TREATMENT IN THE PREVENTION OF VASO-OCCLUSIVE EPISODES (VOES) IN PATIENTS (PTS) WITH SICKLE CELL DISEASE (SCD)

Background: SCD is a group of autosomal recessive red blood cell (RBC) disorders caused by a single point mutation in the β-globin gene, with either homozygous inheritance or heterozygous co-inheritance with other pathogenic variants of the β-globin gene. Hemoglobin S, produced as a result of this point mutation, polymerizes within RBCs under certain conditions, distorting them and generating dense and sickle RBCs. These pathologic RBCs contribute to microvascular occlusions, which may present as acute painful episodes called VOEs. Pts with SCD may also have severe chronic anemia, chronic pain, immune dysfunction, and progressive multi-organ damage. Current therapies for SCD include hydroxyurea, as well as newer treatments such as L-glutamine, crizanlizumab, and voxelotor. Despite these treatments, considerable morbidity and mortality among pts with SCD represents a significant unmet medical need. Complement pathway activation has been reported in pts with SCD at baseline, in acute pain crises, and in delayed hemolytic transfusion reaction. Accumulating nonclinical data suggest the potential multimodal role for complement dysregulation in the pathophysiology of SCD, including vaso-occlusion, hemolysis, inflammation, thrombogenicity, endothelial activation, and end-organ damage.1 The complement pathway can be targeted with crovalimab, a novel anti-C5 monoclonal antibody that allows for small-volume subcutaneous (SC) self-injection. In a Phase 1/2 paroxysmal nocturnal hemoglobinuria (a complement-mediated disorder) study, crovalimab showed rapid and sustained complement inhibition with promising efficacy and safety.2 Aim: CROSSWALK-c (NCT05075824) is a randomized, double-blind, placebo-controlled, Phase 2a study evaluating the efficacy and safety of crovalimab as adjunct therapy in preventing VOEs in pts with SCD. Methods: Pts aged 12 to 55 years, weighing ≥40 kg, with a confirmed diagnosis of SCD, homozygous hemoglobin S (HbSS) or sickle cell β0 thalassemia (HbSβ0), and presenting with 2 to 10 VOEs are eligible, including pts on concurrent SCD-directed therapies. Vaccinations against Neisseria meningitidis, Haemophilus influenzae type B, and Streptococcus pneumoniae are required. Pts with a history of hematopoietic stem cell transplant will be excluded. Eligible pts will be randomized 1:1 to the crovalimab or placebo arms (Figure). An initial intravenous loading dose of crovalimab or placebo will be given on Week 1, Day 1, followed by SC dose on Week 1, Day 2, and then weekly SC doses on Weeks 2–4. Starting Week 5, a maintenance dose will be given every 4 weeks for 48 weeks. All study treatment will be given according to a weight-based tiered dosing schedule (pts weighing ≥ 40 kg to < 100 kg and pts ≥ 100 kg). The primary objective is to evaluate the efficacy of crovalimab vs placebo based on the annualized rate of medical facility VOEs. Key secondary efficacy objectives are the annualized rate of acute chest syndrome, the annualized rate of home VOE, and change in urinary albumin–creatinine ratio, tricuspid regurgitant jet velocity, and Patient-Reported Outcomes Measurement Information System (PROMIS)-Fatigue score in adults, from baseline to Week 49. Safety, pharmacokinetic, immunogenicity, and exploratory biomarker objectives will also be evaluated. Protocol updates are in progress. Results: Primary results are expected in July 2024. Summary: CROSSWALK-c is enrolling pts with SCD and chronic VOEs in six countries.

Ravulizumab for the treatment of myasthenia gravis

Introduction Myasthenia gravis (MG) is a neurological B-cell mediated autoimmune disorder affecting the neuromuscular junction. MG therapeutics have always relied on non-selective immunosuppression with oral steroids and non-steroidal immunosuppressants, mainly with good clinical response. However, clinical stabilization is often reached at the cost of many troublesome side effects and up to 15% of MG patients are deemed as refractory to conventional immunosuppression. This highlights the need of a more targeted and efficacious therapeutic approach. Results from the randomized-controlled period of the CHAMPION study demonstrate a good safety, tolerability, and efficacy profile of ravulizumab compared to placebo. Like eculizumab, ravulizumab is an anti-C5 monoclonal antibody, but with an enhanced pharmacokinetic profile, that allows dosing every 8 weeks. Areas covered We provide an overview of ravulizumab biological features and results from the phase III CHAMPION MG (NCT03920293) study. Expert opinion Data of the CHAMPION MG trial demonstrate that ravulizumab is effective and safe in the treatment of generalized MG. Having a rapid clinical effect, with long-term clinical response, ravulizumab could represent a selective immunosuppressive drug of choice in the future therapeutic algorithm of MG, where conventional immunosuppressants slowly leave room for newer drugs with a more targeted mechanism of action.

Complement biomarkers reflect the pathological status of neuromyelitis optica spectrum disorders.

Complement is involved in the pathogenesis of neuroimmune disease, but the detailed pathological roles of the complement pathway remain incompletely understood. Recently, eculizumab, a humanized anti-C5 monoclonal antibody, has been clinically applied against neuroimmune diseases such as myasthenia gravis and neuromyelitis optica spectrum disorders (NMOSD). Clinical application of eculizumab is also being investigated for another neuroimmune disease, Guillain-Barré syndrome (GBS). However, while the effectiveness of eculizumab for NMOSD is extremely high in many cases, there are some cases of myasthenia gravis and GBS in which eculizumab has little or no efficacy. Development of effective biomarkers that reflect complement activation in these diseases is therefore important. To identify biomarkers that could predict disease status, we retrospectively analyzed serum levels of complement factors in 21 patients with NMOSD and 25 patients with GBS. Ba, an activation marker of the alternative complement pathway, was elevated in the acute phases of both NMOSD and GBS. Meanwhile, sC5b-9, an activation marker generated by the terminal complement pathway, was elevated in NMOSD but not in GBS. Complement factor H (CFH), a complement regulatory factor, was decreased in the acute phase as well as in the remission phase of NMOSD, but not in any phases of GBS. Together, these findings suggest that complement biomarkers, such as Ba, sC5b-9 and CFH in peripheral blood, have potential utility in understanding the pathological status of NMOSD.

Novel therapeutic agents for hemolytic anemia

In recent years, it has become clear that various diseases are caused by complement (related molecule) abnormalities (complementopathies) or are exacerbated by complement (complement-related diseases), and novel therapeutic agents targeting complement (anti-complement agents) are now being developed. Paroxysmal nocturnal hemoglobinuria (PNH) is a hematopoietic stem cell disorder characterized by complement-mediated intravascular hemolysis due to a deficiency of complement regulatory factors, making it a perfect candidate for anti-complement agents. In 2007, the anti-C5 monoclonal antibody eculizumab was approved for PNH, as the first anti-complement agent. The indications for eculizumab are expanding, and aggressive development is underway for new anti-complement agents, not only for PNH but also a variety of other diseases. In addition, the anti-C1s antibody sutimlimab was approved last year for the treatment of cold agglutinin disease, a form of autoimmune hemolytic anemia. This presentation overviews novel anti-complement agents for these hemolytic anemias.

Crovalimab. Anti-C5 monoclonal antibody, Treatment of paroxysmal nocturnal hemoglobinuria, Treatment of atypical hemolytic uremic syndrome, Treatment of vaso-occlusive crisis in sickle cell disease

Crovalimab. Anti-C5 monoclonal antibody, Treatment of paroxysmal nocturnal hemoglobinuria, Treatment of atypical hemolytic uremic syndrome, Treatment of vaso-occlusive crisis in sickle cell disease

Six-Month Outcomes in Patients with Complement Mediated Thrombotic Microangiopathy Treated with Complement Inhibitors in the Real World

Background Complement-mediated (CM) thrombotic microangiopathy (TMA), also known as atypical hemolytic uremic syndrome, is a serious and potentially life-threatening disorder. Anti-C5 monoclonal antibodies (aC5-mab) reduce the morbidity and mortality. Experience outside clinical trials has been limited due to the rarity of the condition. Aims To examine the outcomes of patients diagnosed with CM-TMA treated outside clinical trials. Methods Retrospective, single-institution study. The inclusion criteria required a diagnosis of CM-TMA (laboratory values consistent with TMA syndrome or TMA on a biopsy, with normal ADAMTS13 and absent shiga toxin) and available 6 month follow up data. Day 1 refers to the first day of therapy with aC5-mab. Results Twenty subjects met our inclusion criteria for this report. All were hospitalized during their initial diagnosis. Four (20%) passed away during the hospitalization, while another 2 (10%) died after hospitalization but before 6 months. Fourteen individuals made it to the 6 month follow up. Initiation of aC5-mab occurred at a median of 11 (3 to 48) days after the initial TMA Event. All patients received aC5-mab while hospitalized. Median laboratory values prior to aC5-mab demonstrated: platelets 81.5/uL, LDH 758 U/L, Cr 3.8 g/dL, and hemoglobin 8.6 g/dL. Median values for those who died during hospitalization and before 6 months were: platelets 79/uL, LDH 1044 U/L, Cr 2.1 g/dL, and hemoglobin 9.1 g/dL. Median values at discharge for surviving patients during hospitalization were: platelets 212/uL, LDH 332 U/L, Cr 3.2 g/dL, and hemoglobin 8.0 g/dL. Median values at 6 months were: platelets 201/uL, LDH 231.5 U/L, Cr 1.8 g/dL, and hemoglobin 11.4 g/dL. Renal replacement therapy (RRT) was administered to 17 subjects while receiving aC5-mab, with 7 patients receiving RRT prior to admission. At hospital discharge, 8 patients were on RRT, and at 6 months, 5 individuals remained on RRT. Five (25%) patients had kidney transplants prior to the diagnosis of CM-TMA. Six subjects died, 4 during the hospitalization that led to the diagnosis of CM-TMA and 2 after discharge. The causes of death during hospitalization were severe pneumonia (Day 4), multi-organ failure from lupus flare (Day 6), acute hypoxic respiratory failure from pulmonary hypertension (Day 24) and aspiration pneumonia (Day 47). After hospital discharge, 1 individual who had completed 4 weekly doses of aC5-mab passed away due to CMV pneumonia and sepsis 1 month later. Another patient expired 5 weeks after discharge due to sepsis from an intra-abdominal infection four weeks after the last dose of aC5-mab. Fourteen subjects remained alive at 6 months; 12 continued aC5-mab and 2 had stopped it after 4 and 5 months of therapy with no complications at 6 months. Conclusion This is a real-world study of patients with newly diagnosed CM-TMA treated with aC5-mab that provides 6-months follow-up data. Our findings confirm the efficacy of aC5-mab at treating CM-TMA. One of the most important findings from this study includes the description of 6 patients that died after initiation of therapy with aC5-mab. This might be due to our aggressive use of aC5-mab in critically ill patients (selection bias). In these patients the laboratory criteria recommended to diagnose CM-TMA can overlap with other conditions leading to significant variability in the management. Limitations to this study include the retrospective nature and sample size. Further studies to assess the use of aC5-mab in critically ill patients and criteria to define the subjects unlikely to benefit from aC5-mab are urgently needed. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

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

Development of an Automated Complement C5 Functional Assay for Personalized Monitoring of Patients on C5 Inhibitors

Abstract Background Humanized anti-C5 monoclonal antibody therapeutics has been heralded as a breakthrough treatment for Paroxysmal Nocturnal Hemoglobinuria and atypical Hemolytic Uremic Syndrome. Therapeutic drug monitoring is currently not widely available but assessing complement blockage maybe useful to monitor and optimize Eculizumab or Ravlizumab treatment efficacy. Recent studies have suggested using C5 functional assays as a specific target to assess complement blockage. The aim of this study was to assess the analytical performance of an automated C5 functional assay we developed by modifying the complement CH50 assay used in our laboratory. Methods Patient sera mixed in different ratios (20-90%) with commercially available C5-deficient (C5d) serum (Quidel corp. SD) were tested for lytic activity using the CH50 liposome assay (Optilite, Binding site, Birmingham, UK). Normal lysis ensures intact C5 functional activity exclusively from the patient serum. A ratio that led to normal lysis in healthy sera and in patient sera defective in complement factors other than C5 was considered optimal. This ratio was adopted for preliminary reference intervals (n=34 normal donors) using bi-weight quantile method estimation at a 90% confidence interval. Accuracy was assessed by recovery studies. Specimens (n=2) were created with varying levels of C5 functional activity using Eculizumab (Biovision, CA). Recovery was calculated (measured/expected) by adding back 100 ug/mL of purified C5 (Quidel corp. SD) and comparing the CH50 values to the original results. To evaluate specificity, patient specimens (n=22) defective in complement components other than C5 (C2, C3, C4) were mixed with C5d and lytic activity measured. Results A ratio of 75% C5d to 25% patient serum was used to establish a reference interval of 32.3 – 46.7 U/mL. The two accuracy samples had initial CH50 values of 37.9 and 41.7 U/mL and 14.2 and 20.6 U/mL after Eculizumab depletion, respectively. Adding C5 back to the Eculizumab-depleted samples yielded values of 36.5 and 39.9 U/mL and recoveries of 96%. The non-C5 complement-deficient specificity samples had low CH50 values ranging from 11.8 to 28.8 U/mL. After mixing with C5d, 21/22 samples demonstrated low-normal or normal lytic activity (range: 28.4 -41.6 U/mL). Conclusion A ratio of 75% C5d to 25% patient serum was optimal for maintaining CH50 activity in normal specimens and recovering activity in specimens with complement deficiencies other than C5. The C5-depleted specimens did not regain normal CH50 activity after mixing with C5d serum. Adding C5 to these specimens regained normal CH50 activity, confirming that C5 was non-functional and the C5 inhibitor was not interfering with the assay. Specimens’ defective in complement components other than C5 recovered lytic activity when mixed with C5d serum in 95.5% of the specimens, confirming the analytical specificity of the assay. These data demonstrate an acceptable analytical performance for the C5 functional assay developed.

Comparison of outcomes after plasma therapy or eculizumab in pediatric patients with atypical hemolytic uremic syndrome.

Atypical hemolytic uremic syndrome (aHUS) is an ultra-rare and life-threatening disease. For decades, plasma therapy was used to manage patients with aHUS. Since eculizumab, a recombinant humanized anti-C5 monoclonal antibody, was approved for treatment of aHUS, it has been used to treat patients with aHUS. Here, we examined the effectiveness of eculizumab and plasma therapy, respectively in the treatment of pediatric patients with aHUS. Data were collected from questionnaires sent to 75 institutions known to be treating thrombotic microangiopathy (TMA). A total of 24 patients were evaluable, in which no recurrence of TMA was reported at last observation. There were four therapy groups: two patients receiving supportive therapy, one receiving plasma therapy alone, 17 switching from plasma therapy to eculizumab (therapy switched), and four receiving eculizumab alone. Among 17 patients of therapy-switched group, only one patient achieved complete remission at the end of plasma therapy, 15 patients achieved complete remission after eculizumab initiation, and two patients reached end-stage renal disease. Adverse events were reported in nine cases; among these, meningococcal infection, anaphylaxis, and eculizumab-related infusion reaction were reported among those treated with eculizumab. This study provided substantial evidence from a Japanese population that the conversion from plasma therapy to eculizumab therapy should be considered in patients with aHUS who show an incomplete response to plasma therapy. In addition, although no new safety events were detected, careful attention should be paid to meningococcal infection, eculizumab-related infusion reactions and allergic reactions with administration of eculizumab.

Rapidly evolving necrotic skin lesions of the face

Rapidly evolving necrotic skin lesions of the face