Figure 7. Decrease in Indirect Bilirubin in Response to APL-2

Inhibition of C3 With APL-2 Controls Hemolysis and Increases Hemoglobin Levels in Subjects With Autoimmune Hemolytic Anemia (AIHA)

Abstract #3623 Poster #3623

Morie A. Gertz, MD¹; Eloy Roman, MD²; Bruno Fattizzo, MD³; Merrill Shum, MD⁴; Wahid T. Hanna, MD⁵; Gregory L. Ortega, MD⁶; Darla Liles, MD⁷; Francis Senecal, MD⁸; Steven R. Lentz, MD⁹; Mohamed Hamdani, MS10; Frank Stout, MS10; Alice H. Shen10; Pascal Deschatelets, PhD11; Cedric G. François, MD, PhD11; Federico V. Grossi, MD, PhD10

¹Mayo Clinic, Rochester, MN; ²Lakes Research, Miami Lakes, FL; ³Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy; ⁴The Oncology Institute of Hope and Innovation, Whittier, CA; ⁵University of Tennessee Medical Center/Cancer Institute, Knoxville, TN; ⁶Mid Florida Hematology and Oncology Center, Orange City, FL; ⁷Brody School of Medicine, East Carolina University, Greenville, NC; ⁸Northwest Medical Specialties, PLLC, Tacoma, WA; ⁹University of Iowa Hospitals and Clinics, Iowa City, IA; 10Apellis Pharmaceuticals, Inc., Waltham, MA; 11Apellis Pharmaceuticals, Inc, Crestwood, KY

Background

Methods

Results: Demographics and Baseline Characteristics

Results CAD: Changes in Hematologic and Blood Chemistry Parameters

Results wAIHA (C3+): Changes in Hematologic and Blood Chemistry Parameters

Results Continued

Autoimmune hemolytic anemia (AIHA) is a group of rare autoimmune diseases characterized by hemolysis mediated by autoantibodies directed against self-proteins on the surface of red blood cells (RBCs)¹; the resulting immune complexes can activate the classical complement pathway²AIHA is associated with life-threatening outcomes such as thrombosis and pulmonary embolism³The two most common subclasses are warm antibody (wAIHA; 60-70%) and cold agglutinin disease (CAD; 20-25%).4,5 No therapies have been approved for either CAD or wAIHA⁵AIHA is classified by the immunoglobulin (Ig) isotype involved and the optimal temperature for binding RBCs⁴: wAIHA is mediated predominantly by IgG, while 90% of CAD is mediated by IgM isotypes5,6

Hemolysis in CAD seems to be entirely complement-mediated as 100% of patients present with a positive direct antiglobulin test monospecific for C3 (DATmono C3+)⁷In contrast, not all cases of wAIHA are complement-mediated. Between 20% and 35% are only DATmono IgG+ (ie, DATmono C3−).⁸ Thus, the extent of involvement of complement activation in hemolysis in this group of patients is unclearExtravascular hemolysis, in which C3b coating of RBCs leads to phagocytosis of RBCs by macrophages in the liver or spleen, has been reported to be the unique route of hemolysis in wAIHA² (Figure 1)In CAD, extravascular hemolysis is the predominant route of hemolysis, although in severe cases, intravascular hemolysis may occur through formation of membrane attack complexes in RBC membranes. When intravascular hemolysis occurs, free heme from destroyed RBCs can mediate further complement activation via the alternative pathway² (Figure 2)APL-2 is a pegylated cyclic peptide that binds to C3, exerting broad inhibition of the complement cascade and helping the body restore normal complement activity⁹

Aim: To assess whether inhibiting complement C3 with APL-2 prevents both intravascular and extravascular hemolysis in AIHA patients, thus reducing anemia and its associated signs and symptoms⁸Study Design: A phase 2, open-label study (APL2-CP-AIHA-208) being conducted in the US and Brazil is assessing the safety, tolerability, efficacy, and pharmacokinetics (PK) of daily subcutaneous (SC) doses of APL-2 (270 mg/d or 360 mg/d) administered to subjects with wAIHA or CAD. Endpoints include hemoglobin (Hb), transfusion requirements, absolute reticulocyte counts (ARC), lactate dehydrogenase (LDH), haptoglobin, bilirubin, and FACIT fatigue score (Figure 3)

Data presented are from the ongoing study. As of November 2018, a total of 21 subjects have been enrolled: 12 with CAD and 9 with wAIHA. Of the subjects with wAIHA, 7 were DATmono C3+ and 2 were DATmono C3− (Table 1)Of the 2 DATmono C3− wAIHA subjects, one had a slight decrease in Hb after initiation of APL-2 therapy, APL-2 was stopped at day 24, and the subject will withdraw from the study. The other subject received APL-2 therapy for 56 days and continues in the study but has not had clinically significant changes in Hb or hemolytic markers from baseline. For wAIHA, demographics, Hb and hemolytic markers data presented are only of subjects with DATmono C3+; both C3- subjects are excluded

Nine of 12 CAD (75%) and 8 of 9 wAIHA subjects (88.9%) experienced at least one AE, mainly grade 1-2Most AEs were considered unrelated to APL-2Ten SAEs were reported by 6 subjects; all were considered unlikely to be related to APL-2, and 9 of the 10 SAEs have resolvedA total of 5 grade 3 AEs (oral squamous cell carcinoma, hemolytic flare, pneumonia, purpura, acute kidney injury) were reported by 4 subjects; a total of 5 grade 4 AEs (high calcium, high creatinine, hypoxia, hemolytic flare) were reported by 2 subjects, who discontinued and will withdraw from the studyNo grade 3 or 4 AEs were considered to be treatment related

References 1. Anemia, hemolytic, acquired autoimmune. National Organization for Rare Disorders Web site. https://rarediseases.org/rare-diseases/anemia-hemolytic-acquired-autoimmune/. Accessed March 1, 2018. 2. Berentsen S. Role of complement in autoimmune hemolytic anemia. Transfus Med Hemother. 2015;42(5):303-310. 3. Sonikpreet S, Oberoi G, Kumar S. Case report: autoimmune hemolytic anemia with venous thromboembolism, a common complication of a rare disease. Blood. 2014;123:4869. 4. Bass GF, Tuscano ET, Tuscano JM. Diagnosis and classification of autoimmune hemolytic anemia. Autoimmun Rev. 2014;13(4-5):560-564. 5. Barcellini W. Pitfalls in the diagnosis of autoimmune haemolytic anaemia. Blood Transfus. 2015;13(1):3-5. 6. Berentsen S, Ulvestad E, Langholm R, et al. Primary chronic cold agglutinin disease: a population based clinical study of 86 patients. Haematologica. 2006;91(4):460-466. 7. Data on file, Apellis Pharmaceuticals. In. 8. Issitt PD. Serological diagnosis and characterization of the causative autoantibodies In: Chaplin HJ, ed. Immune Hemolytic Anemias New York, NY: Churchill Livingstone; 1985:1-47. 9. El Mehdi D, Grossi FV, Deschatelets P, et al. APL-2, a complement C3 inhibitor, may potentially reduce both intravascular and extravascular hemolysis in patients with paroxysmal nocturnal hemoglobinuria. Molecular Immunology. 2017;89:115.

APL-2 increases Hb values both in CAD and in wAIHA (C3+) within the first weeks of treatment

APL-2 reduces both intra- and extravascular hemolysis, as shown by reductions in LDH, bilirubin and reticulocytes

APL-2 effect seems linked to C3+ in wAIHA, but further testing in DATmono C3- subjects is required

APL-2 appears to be safe and well tolerated in patients with AIHA

Summary

Table 3. Treatment With APL-2 Has Been Safe and Well-Tolerated

Figure 11. Decrease in Indirect Bilirubin in Response to APL-2

Figure 8. Increase in Hemoglobin (Hb) in Response to APL-2

Figure 3. Key Eligibility Criteria and Study Design

Figure 10. Decrease in Absolute Reticulocyte Count (ARC) in response to APL-2

Figure 9. Decrease in LDH in Response to APL-2

ARC = absolute reticulocyte count; BMRI = bone marrow responsiveness index [(absolute reticulocyte count) × (subject’s Hb/normal Hb)]; CAD = cold agglutinin disease; Hb = hemoglobin; LDH = lactate dehydrogenase; n = number of subjects reporting data at this timepoint; SD = standard deviation; wAIHA = warm antibody autoimmune hemolytic anemia

n = number of subjects with AEs in that category; m = number of AEs in that category

Table 2. Hematologic Parameters (All Subjects)

Table 3 provides a summary of all hemolytic parameters in both CAD and wAIHA (C3+) subjects.

Mean hemoglobin (Hb) increased from 9.3 g/dL at baseline to 11.3 g/dL at day 56Mean LDH decreased from 306.9 U/L at baseline to 150.2 U/L at day 56

Mean indirect bilirubin decreased from 0.8 mg/dL at baseline to 0.4 mg/dL at day 56 Mean reticulocyte count decreased from 185.5 × 10⁹/L at baseline to 61.1 × 10⁹/L at day 56

Figure 4. Increase in Hemoglobin (Hb) in Response to APL-2

Figure 6. Decrease in Absolute Reticulocyte Count (ARC) in response to APL-2

Figure 5. Decrease in LDH in Response to APL-2

Mean hemoglobin (Hb) increased from 8.7 g/dL at baseline to 12.1 g/dL at day 56, with sustained benefit as presented by a mean Hb of 12.6 g/dL at day 168Mean LDH decreased from 487.8 U/L at baseline to 173.4 U/L at day 56, with sustained benefit as represented by a mean LDH of 143.5 U/L at day 168

Mean indirect bilirubin decreased from 1.9 mg/dL at baseline to 0.5 mg/dL at day 56, with sustained benefit as represented by a mean indirect bilirubin of 0.9 mg/dL at day 168Mean reticulocyte count decreased from 137.5 × 10⁹/L at baseline to 46.65 × 10⁹/L at day 56, with sustained benefit as represented by a mean reticulocyte count of 70.85 × 10⁹/L at day 168

Table 4. Disposition

Figure 2. Role of Complement in CADFigure 1. Role of Complement in wAIHA

Normal range, 30-100 × 10⁹/L Normal range, 0.1-0.75 mg/dL

Normal range, 12-17.5 g/dL

Normal range, 0.1-0.75 mg/dL

Normal range, 87-252 U/L

Normal range, 87-252 U/L

Normal range, 30-100 × 10⁹/L

Normal range, 12-17.5 g/dL

Table 1. Subject Demographics and Baseline Characteristics

CAD= cold agglutinin disease; n=number of subjects; SD=standard deviation; wAIHA=warm antibody autoimmune hemolytic anemia

HH

H

Hs

r H

C3b

C3b

C3b

C3b

Optimum 37°C

Autoantibody antigen complex activates complement classical pathway

IgG autoantibodies

C1q

Extravascular hemolysis

Phagocytosis through C3bR

HH

HH

s

rH

HH

HH

s

rH C1q

IgM

MAC

Extravascular hemolysis(Liver mainly)

Phagocytosis through C3bR

Optimum 37°C

Production of cold agglutinin

autoantibodies

Below 30°C

In body extremities, IgM binds to RBCs, leading to activation of classical

complement pathway

Intravascular hemolysis(subjects with severe acute exacerbation)

At 37°C

Hemolysis upon recirculation to central parts of the body

C5b

C3b

C3b

C3b

C3b

C3b C3b