GQ-501 is a helper-dependent adenoviral vector expressing proteoglycan 4 (also known as lubricin) and interleukin-1 receptor antagonist (IL-1Ra), and is being developed for osteoarthritis. Following intraarticular injection, GQ-501 enters the joint cells and turns them into factories for production of the therapeutic proteins. Proteoglycan 4 has a biomechanical effect (increase in lubrication) and inhibits molecular pathways that promote disease progression. IL-1Ra inhibits the IL-1 pathway, which is one of the key mediators of inflammation and structural changes in osteoarthritic joints. Thus, GQ-501 has several mechanisms of action against osteoarthritis. GQ-501 is currently at preclinical stage.

The target population for GQ-501 will be initially knee osteoarthritis patients and can be later expanded to other types of osteoarthritis.