Abstract: Abstract 1033 Paroxysmal nocturnal hemoglobinuria (PNH) is a chronic and life-threatening hematopoietic stem cell disorder characterized by deficiency of the GPI-anchored complement inhibitory proteins CD55/59. Chronic hemolysis from this deficiency leads to serious clinical morbidities including thromboembolism, chronic kidney disease, and increased mortality. The International Clinical Cytometry Society (ICCS) recommends multiparameter high sensitivity flow cytometry (HSFC) as the method of choice for diagnosing PNH. The ICCS also provides guidance on the clinical indications for testing for PNH, including patients (pts) with bone marrow failure (BMF), unexplained cytopenias, unexplained thrombosis, hemoglobinuria and hemolysis. The aim of this study is to use HSFC with sensitivity up to 0.01% to analyze 6,897 pts who were screened for PNH clones utilizing CD235a/CD59 for RBCs, FLAER/CD24/CD15/CD45 for neutrophils and FLAER/CD14/CD64/CD45 for monocytes. We evaluated the clinical indications for PNH testing with the provided ICD-9 diagnostic (DX) codes and examined the change in PNH clone sizes among pts who had follow-up studies in 3–12 months. Based on a sensitivity of at least 0.01%, 6.1% of all pts (421/6897) were found to be PNH positive. Of those pts, 5,545 pts (80.1%) had ICD-9 DX codes provided. The distribution of PNH clone sizes in these PNH+ pts is shown in Figure 1. Aplastic anemia (AA) and hemolytic anemia comprised the most common reasons for testing. In bone marrow failure syndromes, AA pts had the highest incidence of PNH+ clones, 26.3%, followed by pts with unexplained cytopenia, 5.7%, myelodysplastic syndrome (MDS), 5.5%, and anemia (unspecified or in chronic illness), 3.6% (Table 1). The incidence of PNH+ clones for symptoms such as hemolytic anemia was 22.7%, followed by hemoglobinuria 18.9%, and unspecified hemolysis, 7.9%, unspecified iron deficiency, 2.5%, and thrombosis, 1.4%. Of the 421 PNH positive pts, 89 pts (22%) were identified as having follow-up studies in 3–12 months. These pts were categorized into PNH clone sizes of 0.01% – 0.1% (27 pts, 30%), 0.11% – 1% (7 pts, 8%), 1.1% – 10% (18 pts, 20%) and 10.1% – 100% (37 pts, 42%). Of the 64 pts who had PNH clone sizes of 0.01% – 0.1% or 10.1 – 100%, one patient (0.02%) had a follow-up study that resulted in a change of category. Of the 25 pts with PNH clones sizes between 0.11% – 1% and 1.1% – 10%, 10 pts (40%) had a follow-up study resulting in an increase in category, 6 pts (24%) had a follow-up study resulting in a decrease in category and 9 pts (36%) had a follow-up study resulting in no change in category.Figure 1.Distribution of PNH Clone Sizes based on 421 PNH+ PatientsFigure 1. Distribution of PNH Clone Sizes based on 421 PNH+ PatientsTable 1:Incidence of PNH Clones in Patients with ICD-9 Diagnostic Code at Dahl-Chase Diagnostic ServicesICD-9 Diagnostic CodeGeneral DescriptionIncidence of PNH Clone284, 284.01, 284.8, 284.81, 284.89, 284.9Aplastic Anemia26.3% (94/357)238.7, 238.72, 238.73, 238.74, 238.75, 238.76Myelodysplastic Syndrome (MDS)5.5% (32/585)287.5Unexplained Cytopenia5.7% (13/230)284.1Pancytopenia6.0% (63/1058)285.2, 285.21, 285.29, 285.9Anemia Unspecified3.6% (40/1122)283, 283.1, 283.10, 283.11, 283.19, 283.2, 283.9Hemolytic Anemia22.7% (147/647)791, 791.2Hemoglobinuria18.9% (14/74)790.6, 790.99, 790.4Hemolysis7.9% (18/227)325, 415.1, 415.11, 434, 434.01, 444.22, 451.11, 451.19, 452, 453, 453.0, 453.2, 453.4, 453.41, 453.89, 453.9, 557, 557.1Thrombosis1.4% (14/967)280.9Unspecified Iron Deficiency2.5% (7/278)Other ICD-9 diagnostic codes2.1% (26/1232)Not Provided4.8% (51/1065)Note: Table reflects patients who had more than one ICD9 code associated with their laboratory tests. In this single-laboratory experience, we evaluated the incidence of PNH in these high risk groups. In this study, 26.3% of pts with the diagnosis of BMF had PNH+ clones detected, underscoring the need to test this group of pts. The study confirmed the utility of testing pts with unexplained hemolytic anemia, hemolysis and hemoglobinuria where the combined rate of positivity was 48%. In addition, this study highlights the need to monitor pts with small PNH clones by HSFC analysis as these pts may show significant variation over time. This examination of ICD-9 DX code association with presence of PNH+ clones confirms the need to actively test high risk populations for PNH based on the ICCS recommendations to ensure accurate diagnosis and early intervention. Disclosures: Weitz: Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Illingworth:Dahl-Chase: Employment; Alexion: Consultancy, Honoraria, Research Funding.

Abstract: Abstract 1104 Background: Venous thromboembolism (VTE) is a major complication in cancer patients. The traditional treatment algorithm for VTE of UF or LMW heparin followed warfarin is associated with a higher risk of recurrent VTE and bleeding in cancer patients. A recent randomized trial has demonstrated that initial treatment and secondary prophylaxis with LMWH is associated with a lower VTE recurrence when compared to secondary prophylaxis with warfarin. We initiated a single arm Phase 2 IRB approved study to evaluate the efficacy and safety of once daily tinzaparin for the initial treatment and extended prophylaxis (6 months) of VTE in cancer patients. Included in this study was a prospective analysis of plasma biomarkers to assess whether any biomarkers could predict treatment failure or be predictive of patient survival. Methods: Patients (pts)with objectively confirmed symptomatic deep vein thrombosis (DVT), pulmonary embolism (PE) or unexpected PE detected on staging CT scans by the criteria of OConnell et al. (JCO 24:4928, 2006) were eligible for this study, if they had an ECOG score 〈 2 and an estimated 6 month survival. After informed consent, treatment was initiated with tinzaparin 175 U/Kg for 6 months. Planned enrollment was 100 pts. Pts who completed the 6 month study could continue on treatment for an additional 6 months if clinically appropriate. All pts who received at least one injection of tinzaparin were evaluable for efficacy and safety. Study endpoints were objectively confirmed DVT, PE or major bleeding events. Serial blood samples were obtained prior to treatment, at 1 wk, 1 month, 3 months and 6 months. Biomarkers to be studied included D-dimer (D-D), Thrombin-antithrombin complex (TAT), interleukin 6 and 8 (Il-6, Il-8) and plasma tissue factor. Only pts in whom the pretreatment, I week and 1 month blood samples were collected were included in the biomarker analysis. Results: At time of this submission 91 pts were treated on study. Of 91 pts enrolled 39 (42.9%) have completed the 6 months and 5 (5.5%) remain on active treatment. Eight (8.8%) pts withdrew from study for hospice care and one pt was withdrawn due to poor compliance. Forty-two (46%) pts died before 6 months. Ten (11%) pts continued on treatment after 6 months and one pt transitioned to warfarin treatment. Treatment endpoints included 8 (8.8%) pts with recurrent VTE (5 DVT, 3 PE); 2 occurred within the first 4 wks on treatment and the 6 events before month 3. No recurrent VTE occurred after 12wks. Three pts (3%) had major bleeding events. There were no fatal thrombotic or bleeding events. All deaths were considered due to progressive cancer, although the possible fatal VTE in pts who died at home or in hospice could not be excluded. There were 76 (83.5%) pts were evaluable for the biomarker study. Biomarker data failed to show a correlation between the level of D-D, TAT or Il-6 and patient survival from the time of their thrombotic event. However, in pts who developed recurrent VTE after 1 month, the D-D level at month 1 was higher than the pretreatment in 4/6 (66.7%) patients compared to 8/70 (11.4%) pts with no recurrence in whom month 1 samples were obtained. Conclusion: In this prospective study of tinzaparin for initial treatment and secondary prophylaxis of cancer-associated VTE, treatment appeared both safe and efficacious. Our recurrent VTE event rate of 8.8% compares favorably with the 8% recurrent VTE reported in the pts treated with dalteparin. The 3% of patients who had major bleeding events also compares favorably with the CLOT trial. Survival was difficult to predict at the time of enrollment since 46% failed to survive the 6 months. Biomarker data failed to predict survival, but patients who recurred after the first month were more likely to have month 1 D-D levels greater than pretreatment. The reason for the failure of tinzaparin treatment to effectively suppress thrombin generation in these patients remains unexplained. Disclosures: Tagawa: Leo Pharmaceutical: Research Funding; Celgene: Research Funding. Liebman:Leo Pharmaceutical: Research Funding; Celgene: Research Funding.

Abstract: INTRODUCTION Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, clonal, nonmalignant hematologic disease characterized by complement-mediated red blood cell hemolysis. The current standard of care for patients with PNH is C5 inhibition. Anemia persists in up to ~70% of patients receiving eculizumab and is attributed to persistent intravascular hemolysis (IVH) and mostly to C3-mediated extravascular hemolysis (EVH). Pegcetacoplan is a pegylated pentadecapeptide C3 inhibitor targeting proximal complement to control both IVH and EVH. PEGASUS is a phase 3, open-label, active-comparator controlled study of efficacy and safety of pegcetacoplan versus eculizumab. This post hoc analysis of data from PEGASUS categorized the clinical response to pegcetacoplan or ECU in patients with PNH and hemoglobin & lt;10.5 g/dL (despite stable ECU for ≥3 months). METHODS Hematologic response to treatment was categorized (per Risitano AM, et al. Front Immunol. 2019;10:1157) as complete, major, good, partial, minor, or no response, using number of packed red blood cell transfusions required, hemoglobin level, lactate dehydrogenase (LDH) level, and absolute reticulocyte count (ARC). Complete response: no transfusions required, stable hemoglobin in the normal range, and no evidence of hemolysis (ie, LDH ≤1.5× upper limit of normal, ARC ≤150,000/µL). Major response: no transfusion, normal hemoglobin, but with evidence of hemolysis (LDH & gt;1.5× upper limit of normal and/or ARC & gt;150,000/µL). Good response: no transfusion, but with chronic mild anemia or evidence of hemolysis. Partial response: chronic moderate anemia and/or occasional transfusions ( & lt;3 units/6 months). Minor response: regular transfusions required (3-6 units/6 months). No response: regular and frequent transfusions required ( & gt;6 units/6 months). Nine patients (6 from the pegcetacoplan arm and 3 from the eculizumab arm) did not readily fit within the existing criteria due to the availability of data at week 16. Although these 9 patients were manually categorized identically by the lead and senior author in a blinded, independent manner, they were not included among these data. RESULTS The intention-to-treat population was comprised of 41 patients randomized to pegcetacoplan and 39 patients randomized to eculizumab. Four patients in the pegcetacoplan arm and 1 patient in the eculizumab arm were not evaluable for analysis due to incomplete data at week 16. Altogether, 61.0% of patients (25/41) in the pegcetacoplan arm have achieved at least a good hematological response, in contrast to 5.1% (2/39) of the eculizumab arm. At week 16, the distribution of response categories was as follows (Figure): in the pegcetacoplan arm and eculizumab arm, respectively, complete responses were 36.6% and 0%, good responses were 24.4% and 5.1%, partial responses were 12.2% and 33.3%, minor responses were 2.4% and 23.1%, and no responses were 0% and 28.2%. The addition of the 9 manually categorized patients did not significantly alter the proportions reported here. Among the factors that may contribute to heterogeneity of hematologic response to treatment are impaired bone marrow function, residual IVH, and residual C3-mediated EVH. Bone marrow failure was ruled out, and no difference in LDH was observed, suggesting that the major factor accounting for the difference between the 2 arms was the prevention of C3-mediated EVH (as confirmed by reduction of C3-opsonization of PNH red blood cells). CONCLUSION In PEGASUS, treatment with pegcetacoplan resulted in a greater proportion of patients with better hematological responses compared to eculizumab. These results further support the concept that proximal complement inhibition, by preventing EVH in addition to controlling IVH, leads to clinical and hematological improvement in the treatment of PNH. Disclosures Risitano: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alnylam: Research Funding; Alexion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Samsung: Membership on an entity's Board of Directors or advisory committees; Amyndas: Consultancy; RA pharma: Research Funding; Biocryst: Membership on an entity's Board of Directors or advisory committees; Achillion: Membership on an entity's Board of Directors or advisory committees; Jazz: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Pfizer: Speakers Bureau; Apellis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Weitz:Alexion: Consultancy, Honoraria, Speakers Bureau; Apellis: Consultancy, Honoraria. de Castro:Novartis: Honoraria, Other: Steering committee; Alexion: Honoraria, Research Funding; Biocryst: Honoraria, Other: Data monitoring committee; Apellis: Consultancy, Honoraria, Research Funding. Kiladjian:AbbVie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees. Griffin:Biocryst: Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals: Honoraria, Other: Conference Support. Hamdani:Apellis: Current Employment, Current equity holder in publicly-traded company. Ajayi:Apellis Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Baver:Apellis: Current Employment, Current equity holder in publicly-traded company. Peffault De Latour:Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Amgen: Research Funding; Alexion Pharmaceuticals Inc.: Consultancy, Honoraria, Research Funding. OffLabel Disclosure: Pegcetacoplan is an investigational drug for the treatment of paroxysmal nocturnal hemoglobinuria.

Abstract: Cold agglutinin disease (CAD) is a rare form of autoimmune hemolytic anemia with a substantial burden on patient’s quality of life. CARDINAL was a 2-part, open-label, single-arm, multicenter phase 3 study evaluating the C1s inhibitor, sutimlimab, for treatment of CAD. Part A consisted of the pivotal study phase, with the part B extension phase assessing long-term safety and durability of response including patient-reported outcomes, which is the focus of this report. Altogether, 22 patients continued from part A to part B, majority female (68.2%) with a median age of 71.5 years (range, 55-85). Throughout treatment, score improvement on the Functional Assessment of Chronic Illness Therapy (FACIT)–Fatigue scale exceeded a predefined, group-level clinically important change of ≥5 points vs baseline, with a mean (standard error [SE]) change of 11.7 (3.7) points at week 135. The 12-Item Short Form Health Survey physical and mental component scores remained above baseline, with week 123 mean change (SE) exceeding clinically important changes of 3.9 for physical and 2.8 for mental component scores at 4.7 (2.8) and 3.8 (5.7) points, respectively. EuroQol Visual Analogue Scale, scoring patients’ self-rated health, also remained above baseline with a change of 17.1 (5.6) points at week 135. Patient Global Impression of (fatigue) Severity improved vs baseline, corroborating FACIT-Fatigue scores. Patient Global Impression of Change indicated a reduction in perceived disease burden. Data from CARDINAL part B support sustained alleviation of CAD disease burden after long-term treatment with sutimlimab over 2 years, returning toward baseline upon treatment cessation. This trial was registered at www.clinicaltrials.gov as #NCT03347396.