Our goal is to become a leading biopharmaceutical company transforming the lives of patients with life-threatening complement-mediated diseases by combining our insights into complement with our leadership in macrocycle chemistry technology.

Ra Pharmaceuticals has leveraged the Extreme Diversity™ platform to rapidly develop a portfolio of products that selectively inhibit the complement system and other immune targets, including its lead program zilucoplan. Ra Pharmaceuticals’ transformational technology can provide products to replace injectable biologics for a range of common and rare diseases.


The Complement System

The complement system is a central component of the innate immune system. It is activated in three distinct pathways, referred to as the classical pathway, the lectin pathway, and the alternative pathway. Each pathway is activated by different triggers associated with the presence of an abnormal cell or pathogen. Irrespective of the activation event, these pathways converge on C5, triggering a series of events leading to the formation of a pore in the target cell, which is known as the membrane attack complex, or MAC. In its physiological role, this is an extremely potent agent causing the rupture and destruction of bacterial cell walls.


Normally the complement system is tightly regulated to restrict activation to the site of infection and avoid injury to host tissues, or “self” cell surfaces. Under conditions of excessive or uncontrolled activation, the complement system plays a key role in a range of debilitating autoimmune and inflammatory diseases.

The complement system, which consists of approximately 30 interacting proteins, offers a target-rich opportunity for Ra Pharmaceuticals to leverage its Extreme Diversity™ platform technology to identify peptides that can inhibit certain uncontrolled complement pathway factors involved in complement-mediated diseases.