Pfizer (NYSE: PFE) has registered a Phase I/II clinical trial for PF-08154225, an immune-modulating agent of undisclosed mechanism, in patients with four systemic autoimmune diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), idiopathic inflammatory myositis (IIM), and systemic sclerosis (SSc). The trial, registered as NCT07782450, is listed as not yet recruiting, with an estimated start date of August 2026 and a primary completion date of February 2031.
The study is structured in three sequential parts enrolling a total of 54 participants aged 18 to 70. Part 1a evaluates single ascending doses in patients with SLE or RA, with follow-up through week 16. Part 1b moves to multiple ascending doses in the same populations, with monitoring through week 24. Part 2 expands to all four indications in an open-label, single-arm dose expansion format, with safety follow-up through week 52. The study excludes patients with prior exposure to T-cell engagers, chimeric antigen receptor T-cell (CAR-T) therapy, or stem cell transplant. Secondary endpoints in Part 2 include validated disease-specific activity measures: the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) for SLE, Disease Activity Score 28 using C-reactive protein (DAS28-CRP) for RA, the International Myositis Assessment and Clinical Studies Total Improvement Score (IMACS TIS) for IIM, and the modified Rodnan skin score for SSc. Circulating B-cell counts are also included as a pharmacodynamic endpoint, offering a potential early signal of biological activity.
PF-08154225 is described only as an "immune-modulating agent" in the trial record. Its molecular target, modality, and mechanism of action have not been publicly disclosed by Pfizer. The compound appears in Pfizer's Q2 2026 pipeline update without further elaboration, and no press releases, preclinical publications, or licensing announcements referencing it have been identified.