Amgen's Dazodalibep Meets Primary Endpoint in Phase 3 Trial for Sjögren's Disease

For the estimated 4 million Americans living with Sjögren's disease, a systemic autoimmune condition that currently has no FDA-approved systemic treatments, a new clinical trial result offers the first concrete evidence of a disease-modifying therapy. On September 22, 2026, Amgen announced that its investigational drug dazodalibep met the primary endpoint in the Phase 3 OASIZ 301 study. The trial demonstrated a statistically significant reduction in systemic disease activity among adults with moderate-to-severe cases, marking a critical milestone in the development of a potential first-in-class treatment for the debilitating condition.[1][2][5]

The randomized, double-blind, placebo-controlled trial enrolled approximately 621 patients to evaluate the efficacy and safety of the fusion protein. Researchers measured patient outcomes using the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI), a validated 12-domain clinical tool that tracks disease activity across multiple organ systems. Because Sjögren's can affect the entire body, tracking systemic improvements across these domains is the standard benchmark for determining whether a drug is actually altering the underlying disease process rather than simply masking localized symptoms.[3][4][5]

By Week 48 of the study, patients receiving dazodalibep showed clinically meaningful improvements in their ESSDAI scores compared to those on a placebo regimen. According to Amgen's topline data release, the initial separation in disease activity between the treatment and placebo groups emerged rapidly, becoming measurable as early as Week 4. That early improvement was then sustained throughout the remainder of the nearly year-long evaluation period, providing researchers with evidence of a durable response to the targeted immune therapy.[2][5]

Sjögren's disease is the second most common autoimmune rheumatic disease, yet it remains widely underrecognized in general clinical practice. In this condition, the immune system mistakenly attacks the body's moisture-producing glands, leading to profound and chronic dryness of the eyes and mouth. However, in moderate-to-severe systemic cases like those evaluated in the OASIZ 301 trial, the disease extends far beyond the glands, causing chronic joint pain, debilitating fatigue, neuropathy, major organ involvement, and a significantly increased risk of developing lymphoma.[3][5]

Because there are currently no approved therapies that alter the fundamental course of the disease, clinicians are limited to managing symptoms with topical treatments, immunosuppressants borrowed off-label from other conditions, and palliative care. 'The results mark an important step forward for people living with Sjögren's disease, a condition with significant unmet need and no approved systemic treatment options,' said Dr. Jay Bradner, executive vice president of research and development at Amgen, in a statement accompanying the trial results. Bradner noted that the rapid improvement reinforces the company's confidence in the broader clinical program.[5]

Dazodalibep operates as a potential first-in-class CD40 ligand (CD40L) antagonist fusion protein. Rather than broadly suppressing the entire immune system—which can leave patients vulnerable to severe opportunistic infections—the drug specifically disrupts the costimulatory signaling between T cells, B cells, and other antigen-presenting cells. By blocking this specific communication pathway at the cellular level, dazodalibep aims to halt the targeted autoimmune attack that drives Sjögren's disease without shutting down the body's broader defensive capabilities. This precision represents a significant shift from traditional broad-spectrum immunosuppressants.[1][2][5]

The safety profile observed in the Phase 3 trial aligned closely with earlier Phase 2 data, which had previously demonstrated a 6.3-point reduction in ESSDAI scores at day 169. Amgen reported that the most common adverse events—including nasopharyngitis, urinary tract infections, hypertension, and infusion-related reactions—occurred in at least 5% of treated patients. These side effects were generally characterized as mild to moderate, and discontinuations due to adverse events occurred at a low rate that was balanced across both the treatment and placebo arms.[3][5]

Crucially for the drug's future regulatory prospects, dazodalibep has not shown the thromboembolic safety signals—such as dangerous blood clots—that derailed earlier generations of anti-CD40L monoclonal antibodies. Past attempts to target this specific immune pathway were frequently abandoned in clinical trials due to these severe cardiovascular risks. Proving that dazodalibep can effectively block CD40L without triggering those clotting mechanisms in a large 621-patient cohort represents a significant technical achievement for the fusion protein class and clears a major historical hurdle for this mechanism of action.[3][5]

'Patients with Sjögren's disease contend with debilitating symptoms and systemic manifestations for which no approved disease-modifying therapy exists,' said Dr. Ghaith Noaiseh, associate professor of medicine at the University of Kansas Medical Center and lead investigator of the OASIZ 301 study. 'These topline results provide further support for dazodalibep as an emerging treatment for improving systemic disease activity and represent an important advance for the field.' Noaiseh emphasized that the data validates the long-standing effort to find a targeted intervention for the patient population.[5]

While Amgen has not yet released the specific numerical gap between the treatment and placebo arms, the company plans to present the detailed statistical data at an upcoming medical meeting. The exact magnitude of the ESSDAI score reduction, along with secondary endpoints measuring dryness, fatigue, and joint pain, will determine how the systemic findings translate into daily quality-of-life improvements for patients. Analysts and clinicians are waiting for those full datasets to evaluate the drug's ultimate commercial and clinical profile.[4][5]

The dazodalibep clinical development program is also targeting a second distinct population of patients to broaden the drug's potential label. A parallel Phase 3 trial, known as OASIZ 303, is currently evaluating the fusion protein in patients who have a high symptom burden—such as severe dryness and profound fatigue—but lower overall systemic disease activity. That trial is designed to capture the patients whose daily lives are severely impacted by the disease even if their organ systems are not yet heavily involved.[2][5]

That second trial is expected to complete its evaluation in the fourth quarter of 2026, providing the final piece of the late-stage clinical puzzle for Amgen. If the combined efficacy and safety data package from both OASIZ studies successfully supports regulatory approval, dazodalibep could become the first targeted systemic therapy to reach the market for a condition that currently relies entirely on symptom management. Such an approval would fundamentally alter the standard of care for millions of patients who have spent years waiting for a disease-modifying breakthrough.[1][3][5]