Ra Pharmaceuticals, Inc., a clinical-stage biopharmaceutical company, engages in the discovery and development of novel therapeutics for the treatment of diseases caused by excessive or uncontrolled activation of the complement system. Its peptide chemistry platform delivers enables the production of synthetic macrocyclic peptides that combine the diversity and specificity of antibodies with the pharmacological properties of small molecules. The company's lead product candidate is RA101495, an injection into the tissue under the skin for the treatment of paroxysmal nocturnal hemoglobinuria (PNH). It also develops Factor D inhibition for age-related macular degeneration and geographic atrophy; Oral C5 inhibitor for refractory generalized myasthenia gravis, lupus nephritis, and central nervous system (CNS) diseases; C1s inhibition for autoimmune/CNS diseases. The company has multi-target collaboration and license agreement with Merck & Co., Inc. Ra Pharmaceuticals, Inc. was founded in 2008 and is based in Cambridge, Massachusetts.