Celldex Reports Long-Term Phase 2 Data for Barzolvolimab in Chronic Spontaneous Urticaria

Celldex Therapeutics has shared new long-term results from its Phase 2 study evaluating barzolvolimab in patients with chronic spontaneous urticaria (CSU). The findings were presented during a flash talk session at the European Academy of Allergy and Clinical Immunology (EAACI) Annual Meeting held in Istanbul, Türkiye.

The latest data showed that barzolvolimab delivered rapid, significant, and long-lasting improvements in angioedema symptoms among CSU patients who did not respond adequately to antihistamine treatment. The benefits remained visible even seven months after treatment ended, highlighting the therapy’s potential to go beyond symptom management and potentially modify the course of the disease.

New Data Show Benefits Last Beyond Treatment

According to the results presented at EAACI, patients treated with barzolvolimab continued to experience meaningful control of angioedema symptoms through Week 76, which was approximately seven months after receiving their final dose.

Researchers reported that the treatment produced durable improvements not only during active therapy but also after treatment was stopped. These findings strengthen the growing evidence that barzolvolimab may provide long-term disease control in patients with chronic spontaneous urticaria.

The data also support the ongoing Phase 3 development program for the investigational therapy.

Why Angioedema Matters in Chronic Spontaneous Urticaria

If you look at the burden of CSU, angioedema is one of the most challenging symptoms patients face.

Angioedema causes sudden swelling beneath the skin and can affect areas such as the face, lips, eyes, hands, feet, and throat. The condition can be painful, uncomfortable, and emotionally distressing because of visible swelling and unpredictability.

Approximately 55% of people living with CSU experience angioedema. On average, these patients report around 7.7 angioedema episodes every year.

Patients with CSU-related angioedema often report poorer physical health, lower quality of life, higher rates of anxiety and depression, and greater healthcare utilization compared to patients who do not experience angioedema. They are also more likely to visit emergency rooms, require hospitalization, and experience difficulties with work and daily activities.

For many patients and physicians, becoming completely free from angioedema is considered a major treatment goal.

Rapid Improvements Seen Early in Treatment

The Phase 2b study previously demonstrated that barzolvolimab could quickly reduce angioedema symptoms in patients with antihistamine-refractory CSU.

Researchers observed symptom relief as early as Week 1 of treatment. The improvements continued to increase over time and remained strong throughout 52 weeks of therapy.

The latest analysis adds another important piece to the story by showing that these benefits can continue long after treatment ends.

Off-Treatment Results Highlight Durable Response

One of the most notable findings from the new presentation was the durability of response after treatment discontinuation.

At Week 76, patients continued to show meaningful reductions in angioedema symptoms despite being off therapy for several months.

Among patients who experienced angioedema at the start of the study, up to 64% were completely free of angioedema seven months after receiving their final dose of barzolvolimab.

These results suggest that the therapy may have a lasting impact on the underlying disease process rather than simply controlling symptoms while treatment is ongoing.

Barzolvolimab Shows Potential for Disease Modification

According to Celldex, barzolvolimab has consistently demonstrated high rates of complete response throughout clinical development.

Complete response in CSU means the total absence of itch and hives, which are the two hallmark symptoms of the disease.

The company believes the sustained improvements in itch, hives, quality of life, and angioedema control support the idea that barzolvolimab may help change the long-term course of the disease.

This possibility has shifted attention from traditional symptom control toward the broader goal of disease modification in CSU.

Large Global Phase 3 Program Moves Forward

Celldex is currently conducting two Phase 3 clinical trials evaluating barzolvolimab in chronic spontaneous urticaria.

Enrollment for both studies has already been completed.

The Phase 3 program enrolled a total of 1,939 patients, making it the largest clinical development program conducted in antihistamine-refractory CSU. The studies also included patients who had previously received advanced therapies or were considered difficult to treat.

The global program spans 43 countries and approximately 500 clinical trial sites.

Topline Results Expected in 2026

The company expects topline data from the Phase 3 studies during the fourth quarter of 2026.

If the results are positive, Celldex plans to submit a Biologics License Application (BLA) in 2027.

The growing body of Phase 2 evidence, including the newly presented Week 76 data, continues to support the advancement of barzolvolimab as a potential new treatment option for patients living with chronic spontaneous urticaria and angioedema.

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