Understanding the Complement Cascade and Its Role in Cold Agglutinin Disease. 1 M-CAgD-US-3006 February 2018

Transcription

1 Understanding the Complement Cascade and Its Role in Cold Agglutinin Disease 1 February 2018

2 Instructions This information is provided as an educational resource for healthcare providers. It is not intended to be a substitute for review of the underlying reference materials and scientific literature. Healthcare providers should make all treatment decisions based on their medical judgement and the clinical profile of the individual patient. The following document cannot be copied, modified, used or distributed without the express written consent of Bioverativ. 2 February 2018

3 Pathogenesis of Cold Agglutinin Disease Cold agglutinin associated lymphoproliferative bone marrow disorder A distinct type of LPD LPD, lymphoproliferative disorder. Randen U, et al. Haematologica. 2014;99(3):

4 Pathogenesis of Cold Agglutinin Disease Hemolysis is entirely classical complement pathway dependent C, complement; CA, cold agglutinin. Berentsen S. Br J Haematol. 2011;153(3):

5 Pathogenesis: Therapeutic Implications Distinct clonal B-cell bone marrow disorder 1 Therapeutic implications Hemolysis is entirely classical complement pathway dependent 2 Therapeutic implications BIVV009 BIVV009 is under development and is not approved for the treatment of cold agglutinin disease C, complement; Ig, immunoglobulin; INH, inhibitor. 1. Randen U, et al. Haematologica. 2014;99(3): Berentsen S. Blood. 2014;123(26):

6 The Complement System: A Family of Circulating Proteins in the Blood Responsible for Immune Surveillance 1 Classical Lectin Alternative C, complement protein; MBL, mannan-binding lectin. 1. Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science;

7 The Complement System: A Family of Circulating Proteins in the Blood Responsible for Immune Surveillance 1 Classical Lectin Alternative C, complement protein; MBL, mannan-binding lectin. 1. Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science;

8 The C1 Complex Is the Activation Mechanism of the Classical Complement Pathway 1 C1 complex activates the classical complement pathway: Classical Lectin Alternative 1. The pattern recognition molecule C1q binds items such as immune complexes, apoptotic cells, etc 2. C1q undergoes a conformational change following binding to a target, resulting in C1r autoactivation 3. Activated C1r cleaves and activates C1s 4. Active C1s cleaves C4 and C2, forming the CP/LP C3 convertase C, complement protein; CP, classical pathway; LP, lectin pathway; MBL, mannan-binding lectin. 1. Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science;

9 The Classical Pathway Activates Upon Binding to Antibodies: A Bridge Between the Innate and Adaptive Immune Systems C, complement protein; IgG, immunoglobulin G. 1. Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science;

10 Cold Agglutinin Disease Overview: Autoimmune hemolytic anemia 1 Prevalence 1,2 : ~1/60,000 1/100,000; incidence 3,4 : ~1/300,000 1/1,000,000 ~5000 patients in the United States Patients are often elderly 2 and present with anemia, fatigue, hemoglobinuria, and acrocyanosis 4 Etiology: Primary (idiopathic) 1 Secondary: caused by an underlying condition (eg, infection, malignancy) Majority of patients have detectable clonal B cells responsible for the production of an autoantibody that binds to RBC <37 C (cold) 5 Clinical symptoms: Frequent need for transfusions 1 Chronic anemia with related symptoms (decreased quality of life) 4 Agglutination-associated symptoms 4 Thromboembolic complications4 CA activation in the classical pathway 6 C, complement protein; CA, cold agglutinin; RBC, red blood cell. 1. Berentsen S, et al. Haematologica. 2006;91(4): Gertz MA. Hematol Am Soc Hematol Educ Program. 2006; Sokol RJ, et al. Br Med J. 1981;282: Mullins M, et al. Blood Adv. 2017;1(13): Bass GF, et al. Autoimmunity Rev. 2014;13(4-5): Shi J, et al. Blood. 2014;26(123):

11 µg/ml (mean ± SE) Patients With Cold Agglutinin Disease Are Hypocomplementemic for Upstream Classical Pathway Substrates Healthy C1s a Cold agglutinin disease Compared with healthy individuals, patients with cold agglutinin disease have lower levels of C4 and C2 but not C5, suggesting that the classical pathway is consumed in these patients, but the terminal pathway is not activated (ie, C5 cleavage) 1 Classical 2 Lectin 2 Alternative 2 C4 C2 C5 µg/ml (mean ± SE) Healthy b Cold agglutinin disease µg/ml (mean ± SE) Healthy b Cold agglutinin disease µg/ml (mean ± SE) Healthy Cold agglutinin disease C, complement protein; SE, standard error. a P<0.01; b P< Shi J, et al. Blood. 2014;26(123): Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science;

12 Understanding the Role of Complement in Mediating RBC Destruction in Cold Agglutinin Disease 1 + Normal RBC RBC coated with antibodies Patient Sample Flow cytometry + Complement Lysis Complement-coated RBC FL1-A, fluorescence intensity; FSC-A, forward scatter; RBC, red blood cell. 1. Jager U, et al. ASH 2015; Poster. 12

13 Cold Agglutinin Titers Correlate With the Amount of Complement Deposited on the RBC 1 C3 fragment positive RBC (%) r = 0.76 P< N = 40 samples ,800 22,000 Cold agglutinin titer (1:X) C, complement protein; RBC, red blood cell. 1. Shi J, et al. Blood. 2014;26(123):

14 C3b Is an Eat Me Signal to Cells of the Immune System Macrophage C3b-coated cells Phagocytosis C3b is deposited on the target cell s membrane, promoting its phagocytosis 1 C, complement protein. 1. Wouters D, Zeerleder S. Haematologica. 2015;100(11):

15 An In Vitro Proxy for Extravascular Hemolysis + + Complement + Green dye Normal RBC ± inhibitor RBC coated with complement + Phagocytosis RBC, red blood cell. 15

16 C1s Inhibition Prevents Phagocytosis of RBCs Exposed to Cold Agglutinin Disease Autoantibodies 1 Phagocytosis (mean % ± SE) Phagocytosis 150 C3 fragment positive RBC C3 fragment positive RBC (% control) 0 No serum 25% NHS 10 mm EDTA +100 µg/ml IgG 2a +100 µg/ml TNT003 0 C, complement protein; IgG, immunoglobulin G; mab, monoclonal antibody; NHS, normal human serum; RBC, red blood cell; SE, standard error. 1. Shi J, et al. Blood. 2014;26(123):

17 C1s Inhibition Prevents Complement Dependent Hemolysis Driven by Cold Agglutinin Disease Autoantibodies Cold agglutinin disease autoantibody mediated hemolysis (mean % ±SE) Antibody concentration (µg/ml) IgG 2a TNT003 Thus, an upstream classical pathway inhibitor would prevent both extravascular and intravascular hemolysis 1 C, complement protein; IgG, immunoglobulin G; SE, standard error. 1. Shi J, et al. Blood. 2014;26(123):

18 C1s Inhibitors Prevent Anaphylatoxin Production Generated by Cold Agglutinin Disease Autoantibodies Anaphylatoxin 2 Classical 1 Lectin 1 Alternative 1 IgG 2a TNT003 C4a inhibition (mean % ± SE) C3a inhibition (mean % ±SE) IgG 2a TNT Antibody [Ab] concentration g/ml (µg/ml) C, complement protein; IgG, immunoglobulin G; MBL, mannan-binding lectin; SE, standard error. 1. Murphy K, et al. Janeway s Immunobiology. 8th ed. New York: Garland Science; Shi J, et al. Blood. 2014;26(123): C5a inhibition C5a (% Inhibition) (mean % ±SE) IgG 2a TNT003 18

19 Summary Cold agglutinin disease is an autoimmune hemolytic anemia 1 Cold agglutinins bind to the RBC and activate the classical complement pathway, leading to opsonin (C3b) deposition on the RBC surface and, in some cases, direct cellular lysis 2,3 Opsonin-coated RBCs travel to the liver where they are phagocytosed 2,3 Classical pathway inhibitors that target upstream of C3 and prevent opsonin deposition rescue cells from being phagocytosed or lysed by complement, specifically demonstrating the role of the classical pathway in mediating cold agglutinin driven complement activation 4 Classical pathway inhibitors, therefore, could potentially be efficacious in the treatment of cold agglutinin disease 4 C, complement protein; RBC, red blood cell. 1. Berentsen S, et al. Haematologica. 2006;91(4): Stone MJ. Blood. 2010;116(17): Berentsen S. Clin Lymphoma Myeloma. 2009;9(1): Shi J, et al. Blood. 2014;26(123):