Pacira publishes two-year Phase 1 data for PCRX-201 in knee OA

Pacira BioSciences has announced the publication of two-year Phase 1 results for PCRX-201 (enekinragene inzadenovec), its investigational intra-articular gene therapy for knee osteoarthritis, in the peer-reviewed journal Annals of the Rheumatic Diseases. The open-label study enrolled 72 adults with moderate-to-severe knee OA and found the candidate to be well tolerated following a single local injection, with exploratory measures showing improvements in pain, stiffness and function across all dose cohorts through the full 104-week follow-up period.

The trial was conducted in two parts. The first enrolled 36 participants across low, middle and high dose groups. The second enrolled a further 36 participants who received methylprednisolone immediately before PCRX-201 administration; glucocorticoid pretreatment was associated with a lower rate of joint effusion and greater improvement in clinical outcomes. That finding has since been incorporated into the design of the ongoing Phase 2 ASCEND study.

Clinical context

Stanley Cohen, lead investigator and co-medical director of the Metroplex Clinical Research Center in Dallas, said the safety profile and exploratory outcome improvements over two years "provide a strong scientific rationale for the advancement of PCRX-201 into later-stage clinical development." Jonathan Slonin, chief medical officer of Pacira, noted that if results are confirmed in future studies, the therapy could deliver a treatment effect lasting one year or more, potentially exceeding the three-to-six-month duration of currently available options such as corticosteroid injections.

PCRX-201 is built on a proprietary high-capacity adenovirus (HCAd) vector platform. Pacira says HCAd can carry up to 30,000 base pairs of DNA, enabling delivery of larger or multiple genes than adeno-associated virus (AAV) vectors typically allow, and that the platform supports local administration with the potential for redosing. The company has also reported separately that it implemented a scalable manufacturing process for PCRX-201 and initiated enrolment in Part B of the Phase 2 ASCEND trial (NCT06884865), with first topline readout expected by the end of 2026.

Regulatory and competitive landscape

PCRX-201 holds Regenerative Medicine Advanced Therapy (RMAT) designation from the FDA and Advanced Therapy Medicinal Product (ATMP) designation from the EMA, both of which provide access to enhanced regulatory dialogue and, in the US case, the possibility of accelerated approval pathways. These designations are meaningful but do not guarantee approval; Phase 2 data will need to demonstrate statistical significance on agreed primary endpoints before any filing discussion becomes realistic.

Knee osteoarthritis is a sizeable and underserved indication. Current standard-of-care is largely palliative, with corticosteroid and hyaluronic acid injections offering limited and transient relief, and joint replacement surgery representing the major definitive intervention. A durable single-injection gene therapy would address a recognised gap, but the space is also attracting interest from a number of academic spinouts and gene therapy developers exploring local delivery approaches. Pacira's HCAd platform differentiates on payload capacity and local administration, though the company faces the practical challenge of demonstrating durability and reproducibility at scale. The year-end Phase 2 readout will be the clearest signal yet of whether that differentiation translates into clinically meaningful outcomes.