GQ-203 is a helper-dependent adenoviral vector expressing interleukin-1 receptor antagonist (IL-1Ra) and is being developed for knee osteoarthritis and intervertebral disc degeneration. Following intraarticular injection, GQ-203 enters the joint cells and turns them into factories for production of the therapeutic protein IL-1Ra. IL-1Ra inhibits the IL-1 pathway, which is one of the key mediators of inflammation and structural changes in osteoarthritic joints. GQ-203 has demonstrated a symptomatic and disease-modifying effect in multiple osteoarthritis animal models.

In 2017, Flexion Therapeutics, Inc. (Burlington, MA, USA) acquired the GQ-203 program from GQ Bio [Link zur Pressemitteilung]. In 2021, Flexion Therapeutics, Inc. was acquired by Pacira BioSciences, Inc. (Tampa, FL, USA); since then, the program has been called PCRX-201. PCRX-201 has a completed a Phase 1 clinical trial in 72 knee osteoarthritis patients.