Autoimmune hemolytic anemia (AIHA) comprises a group of rare, autoimmune diseases characterized by autoantibody-initiated premature destruction of red blood cells and classified by the type of immunoglobulin involved in causing the disease and its thermal optimum for binding red blood cells. Complement plays a major role in red blood cell destruction in AIHA through extravascular hemolysis, which corresponds to the removal and destruction of opsonized red blood cells from the blood vessels by the spleen or liver, and intravascular hemolysis, which corresponds to the destruction of the red blood cells following the formation of the membrane attack complex in the membrane of the red blood cells in the blood vessels. We are developing APL-2 as a therapy for two subtypes of AIHA: cold agglutinin disease, or CAD, and warm antibody AIHA, or wAIHA.
There is no FDA-approved drug therapy specifically for either subtype of AIHA. The primary and secondary therapies, which include corticosteroids, splenectomy, alkylating agents and immunosuppressive drugs, are associated with low response rates, relapses and clinically significant adverse effects.
We believe that C3 inhibition has the potential to prevent C3b opsonization and extravascular hemolysis in AIHA patients, and that inhibiting the complement system by targeting C3 may have the same impact, if not greater, as other complement pathway drugs in these diseases.