Fate Therapeutics Presents FT819 CAR T-Cell Data Demonstrating Immune Remodeling and Durable Responses in Systemic Lupus Erythematosus Patients at ACR Convergence 2025

10/26/2025 – 11:30 AM

As of a September 25, 2025 data cut-off-date, 10 patients with treatment-refractory, moderate-to-severe Systemic Lupus Erythematosus (SLE) were treated with a single dose of FT819 with less-intensive or no conditioning chemotherapy

Favorable safety profile with no dose-limiting toxicities supports plan to enable same-day discharge post FT819 treatment broadening patient accessibility

All patients surpassing a 3-month post-treatment time point (n=5) showed significant reductions in the SLE Disease Activity Index (SLEDAI-2K) score and Physician’s Global Assessment (PGA)

SLE patients with lupus nephritis (LN) surpassing a 3-month post-treatment time point (n=2) achieved complete renal response (CRR) at 6 months; first patient continues in drug-free Definition of Remission in SLE (DORIS) at 15 months follow-up

Cumulative clinical dataset provides clear evidence for rapid CD19+ B cell depletion and immune remodeling toward a naïve and less pathogenic B-cell repertoire

SAN DIEGO, Oct. 26, 2025 (GLOBE NEWSWIRE) — Fate Therapeutics, Inc. (NASDAQ: FATE), a clinical-stage biopharmaceutical company focused on off-the-shelf cellular immunotherapies derived from induced pluripotent stem cells (iPSCs), presented new and updated data from their Phase 1 clinical trial evaluating FT819 for the treatment of moderate-to-severe systemic lupus erythematosus (SLE) at the American College of Rheumatology (ACR) Convergence 2025 in Chicago. The emerging data suggest FT819 could represent a paradigm shift in how SLE is managed.

“These initial clinical results are encouraging; FT819 demonstrates the potential to transform the treatment landscape for patients with moderate-to-severe SLE, and particularly highlights the possibilities of reduced or no conditioning chemotherapy,” said Bob Valamehr, Ph.D., M.B.A., President and Chief Executive Officer of Fate Therapeutics. “Given the encouraging clinical activity, manageable safety profile, and robust enrollment, we anticipate accelerated patient enrollment as more clinical sites are activated. With a growing network of participating sites, we are dedicated to completing the Phase 1 trial expeditiously. Further, under our RMAT designation, we are actively collaborating with the FDA on a registrational study design, with the goal of commencing a pivotal study next year. We are making robust progress toward our objective of providing FT819 as an on-demand, readily available, and cost-effective solution to alleviate suffering in patients battling SLE and other autoimmune disorders.”

Deep Dive: Assessing the FT819 Data and its Implications for SLE Treatment

The ongoing Phase 1 clinical trial (NCT06308978), is evaluating FT819, an off-the-shelf, CD19-targeted CAR T-cell therapy, in patients with moderate-to-severe SLE, including those with lupus nephritis and extrarenal lupus manifestations. The study is designed to assess the safety, pharmacokinetics, and clinical activity of a single dose of FT819, administered with either a less-intensive conditioning regimen (Regimen A, fludarabine-free, using cyclophosphamide or bendamustine) or a conditioning-free regimen in patients receiving standard-of-care maintenance therapy (Regimen B). As of September 25, 2025, ten patients (8 on Regimen A, 2 on Regimen B) have been treated, offering the following insights:

Less-intensive Conditioning Regimen

• Active Lupus Nephritis: Five patients with active, refractory lupus nephritis (prior therapies ranging from 7 to 8, all with prior B-cell targeted therapy; baseline SLEDAI-2K scores between 8 and 20) were treated with FT819 under the less-intensive regimen. Two patients treated at dose level 1 (DL1, 360 million cells) who reached the 3-month evaluation point showed significant SLEDAI-2K reductions of 16 and 12 points, along with Urine Protein-to-Creatinine ratio (UPCr) reduction to <0.5 mg/mg at 6 months. The patient with a 16-point SLEDAI-2K reduction discontinued steroids, achieving DORIS and complete renal response (CRR) at 6 months, and remained steroid-free with CRR at 15 months. The second patient had a 12-point SLEDAI-2K reduction and CRR at 6 months but experienced a disease flare, with retreatment under consideration at 12 months.
• Extrarenal Lupus: Three patients with active, moderate-to-severe extrarenal lupus (prior therapies 3-10; baseline SLEDAI-2K 14-18) received FT819 under the less-intensive regimen. Two patients had reached the 3-month evaluation. Both received dose level 2 (DL2, 900 million cells). The first patient showed a SLEDAI-2K reduction from 18 to 10 at one-month post-treatment but was restarted on anifrolumab (having previously received it for 3 years) two months after FT819. Continued improvement resulted in DORIS at 6 months post-FT819, which hadn’t been achieved with combination therapy prior to FT819. The second patient demonstrated significant SLEDAI-2K reduction from 16 to 6, PGA reduction from 2.2 to 0.4, and dramatic improvement in FACIT score at 3 months.

Conditioning-free Regimen

• Add-on to Maintenance Therapy: Two patients received FT819 (360 million cells) with no conditioning, as an add-on to mycophenolate mofetil maintenance therapy (one with extrarenal lupus, prior therapies = 5, baseline SLEDAI-2K = 8; the second with lupus nephritis, prior therapies = 8, baseline SLEDAI-2K = 17). The extrarenal lupus patient reached the 3-month evaluation, achieving low lupus disease activity state (LLDAS) by 3 months, sustained at 9 months. Reductions in SLEDAI-2K (8 to 2) and PGA (2 to 0.5) were also observed, with steroids tapered to less than 5 mg / day.

Safety Profile

• Across more than 60 patients treated with FT819 across autoimmune and oncology indications, the safety profile is observed continually with a low incidence of cytokine release syndrome (CRS), no events of immune effector cell-associated neurotoxicity (ICANS), and no events of graft-versus-host disease (GvHD). In SLE patients treated with FT819 (n=8):
  • No ICANS, no GvHD, and 3 patients experienced low-grade CRS (Grade 2 maximum severity in 1 patient, Grade 1 maximum severity in 2 patients).
  • No patients experienced dose-limiting toxicities.
  • All patients were discharged after a short hospitalization post infusion of FT819, supporting the potential for outpatient administration.

Translational Science

• In patients treated with less-intensive conditioning, rapid and sustained CD19+ B cell depletion was observed, with a positive correlation with dose escalation. Upon B cell compartment return, naïve B cell emergence beyond baseline levels was observed, suggestive of an immune reset relating to a reduction in disease burden.
• In patients treated without conditioning, a reduction in CD19+ B cells was observed, alongside reduced B-cell clones and remodeling of the B cell compartment that correlated with disease activity score improvements.
• These results indicate FT819’s capability to remodel the B-cell repertoire with the potential to push it toward a more naïve state, without intensive conditioning chemotherapy. The mechanistic remodeling of the B cell compartment supports immune restoration as a driver of clinical remission, reinforcing transformative potential of FT819 in autoimmune disease treatment.

Strategic Outlook: Program Expansion and Regulatory Strategy

Fate Therapeutics has initiated independent dose-expansion cohorts in anti-neutrophilic cytoplasmic antibody-associated vasculitis (AAV), idiopathic inflammatory myositis (IIM), and systemic sclerosis (SSc). The company is actively engaged with the FDA under its Regenerative Medicine Advanced Therapy (RMAT) designation to finalize pivotal study design to initiate in 2026. They report approximately 600 cryopreserved drug product bags available for the treatment of patients.

Analysts Weigh In: The Path Forward for FT819

While the Phase 1 data is promising, analysts caution that the small sample size limits definitive conclusions about FT819’s efficacy and long-term durability. However, the favorable safety profile and early signs of clinical benefit are encouraging. Success in the planned pivotal trial could solidify FT819’s position as a significant advance in SLE treatment. The company’s iPSC-derived cell therapy platform offers a distinct advantage over traditional autologous CAR-T approaches, potentially enabling broader patient access and reducing manufacturing costs. The progress of FT819 will also be closely watched by other companies developing cell therapies for autoimmune diseases, with advancements potentially validating B-cell depletion as a treatment strategy more broadly.