Enlivex's Allocetra Wins FDA RMAT Designation for Age-Related Knee Osteoarthritis

The FDA has granted Regenerative Medicine Advanced Therapy (RMAT) designation to Allocetra, Enlivex's clinical-stage cell therapy, for the treatment of age-related symptomatic knee osteoarthritis (OA) in patients aged 64 and older.¹ RMAT designation, created under the 21st Century Cures Act, is reserved for cell and gene therapies that show potential to treat, modify, reverse, or cure a condition with significant unmet need, and it comes with the benefits of fast track and breakthrough therapy designations combined, including intensive early FDA engagement and potential eligibility for accelerated approval and priority review.¹

In a press release, Oren Hershkovitz, PhD, CEO of Enlivex, said receiving RMAT designation underscores the strength of the company's clinical data in age-related knee OA and supports its decision to focus development on the patient population that showed the most pronounced benefit in its phase I/IIa trial.¹ Enlivex expects the designation to provide intensive, early FDA engagement as it advances Allocetra through its ongoing phase IIb program.¹

How does Allocetra work?

Allocetra is an allogeneic, off-the-shelf cell therapy composed of donor-derived apoptotic cells. Rather than replacing damaged joint tissue directly, it works by reprogramming macrophages, immune cells that play a central role in driving chronic joint inflammation, back into a homeostatic state. That mechanism targets the underlying inflammatory driver of OA rather than simply managing pain, distinguishing it from existing OA treatments, none of which are FDA- or EMA-approved to slow or reverse structural joint damage.

Genascence's GNSC-001, a first-in-class IL-1 inhibitor gene therapy for knee OA, received RMAT designation from the FDA roughly a year earlier, in July 2025, following a similar rationale around addressing an underlying inflammatory pathway rather than symptoms alone. As Thomas Chalberg, PhD, founder and CEO of Genascence, said of that designation, "The FDA RMAT designation for GNSC-001 underscores the strength of the clinical data to date, recognizing its potential to transform the treatment paradigm for OA," a description of the broader RMAT pathway's significance that applies equally to Enlivex's news, reported in BioPharm International's coverage of the Genascence designation.²

What clinical data support the designation?

Enlivex's RMAT designation follows durable efficacy data from the phase I/IIa stage of its ENX-CL-05-001 trial. Three-month data reported in August 2025 showed that in the primary age group (60 and older), Allocetra produced substantial reductions in pain and improvements in function compared with placebo across multiple efficacy endpoints, with the magnitude and statistical significance of the effect correlating positively with patient age.³ Six-month follow-up data, completed for all patients and reported in November 2025, confirmed that effect held: on a composite pain-and-function endpoint, patients aged 61 and older receiving Allocetra improved by 27.8 points versus 15.5 points in the placebo group, an 80% improvement over placebo (p=0.02), consistent with the earlier three-month results.³

Philip Conaghan, MBBS, PhD, consultant rheumatologist and director of the NIHR Leeds Biomedical Research Centre and a member of Enlivex's Clinical Advisory Board, said the growing burden of knee osteoarthritis from aging and obesity underscores the need for effective new therapies, and that he found the study results so far encouraging as Allocetra continues to be developed as an immune-modulating agent with the potential to pioneer a new therapeutic approach, as reported in Enlivex's November 2025 release announcing the six-month data.³

What happens next?

Enlivex is currently enrolling its global, multicenter, randomized, double-blind, placebo-controlled phase IIb trial evaluating intra-articular Allocetra injections in the same age-related primary OA population, with sites active in the US, Denmark, and Poland.³ The RMAT designation is expected to give the company more frequent formal interactions with the FDA as that trial progresses, with the agency's guidance potentially shaping both trial design adjustments and the ultimate regulatory pathway toward approval.

References

1. Enlivex Receives FDA Regenerative Medicine Advanced Therapy (RMAT) Designation for Allocetra in Age-Related Knee Osteoarthritis. (2026 Jul 13). GlobeNewswire. https://www.globenewswire.com/news-release/2026/07/13/3326135/0/en/enlivex-receives-fda-regenerative-medicine-advanced-therapy-rmat-designation-for-allocetra-in-age-related-knee-osteoarthritis.html
2. Haigney, S. (2025 Jul 18). FDA Grants Regenerative Medicine Advanced Therapy Designation to Gene Therapy for Knee OA. BioPharm International. https://www.biopharminternational.com/view/fda-grants-regenerative-medicine-advanced-therapy-designation-to-gene-therapy-for-knee-oa
3. Enlivex Announces Positive 6-Month Topline Data Demonstrating Durable and Persistent Pain Reduction and Improved Function in Primary Age-Related Patients with Moderate to Severe Knee Osteoarthritis. (2025 Nov 24). GlobeNewswire. https://investors.enlivex.com/press-releases/enlivex-announces-positive-6-month-topline-data-demonstrating-durable-and-persistent-pain-reduction-and-improved-function-in-primary-age-related-patients-with-moderate-to-severe-knee-osteoarthritis/