Celldex Shares Rise 8% as Barzolvolimab Meets Primary Endpoints in Two Phase 3 Trials

Celldex Therapeutics (NASDAQ:CLDX) shares gained 8% on Tuesday after the company reported positive topline results from two Phase 3 trials evaluating barzolvolimab in patients with chronic spontaneous urticaria (CSU).

Both EMBARQ-CSU1 and EMBARQ-CSU2 met their primary endpoints and all key secondary endpoints, demonstrating statistically significant improvements in disease activity compared with placebo.

The trials form part of what Celldex describes as the largest clinical development programme conducted in patients with CSU that has not responded adequately to antihistamines, including those previously treated with or resistant to advanced therapies.

Barzolvolimab Meets Primary Endpoints in Both Studies

The primary endpoint measured the mean change from baseline in the weekly urticaria activity score (UAS7) at Week 12.

In EMBARQ-CSU1, patients receiving the 150 mg dose of barzolvolimab recorded a mean UAS7 change of -20.2, compared with -10.7 for placebo. The 300 mg dose produced a mean change of -20.5.

Results were similar in EMBARQ-CSU2, where the 150 mg dose achieved a mean change of -20.2 and the 300 mg dose recorded -19.7, compared with -11.4 for placebo.

All reported comparisons were statistically significant, with p-values below 0.00001.

Celldex said both doses produced clinically meaningful reductions in disease activity across the two trials.

Complete Response Rates Increase Through Week 24

The studies also evaluated complete response, defined as a UAS7 score of zero, indicating no recorded urticaria activity during the assessment period.

At Week 12, 42.4% of patients receiving the 150 mg dose in EMBARQ-CSU1 achieved complete response, compared with 9.3% in the placebo group.

In EMBARQ-CSU2, complete response was achieved by 45.7% of patients receiving 150 mg of barzolvolimab, versus 12.6% on placebo.

Response rates increased further with continued treatment.

By Week 24, complete response rates for the 150 mg dose had reached 49.0% in EMBARQ-CSU1 and 54.0% in EMBARQ-CSU2.

Treatment Shows Benefits in Difficult-to-Treat Patients

Celldex reported that barzolvolimab also demonstrated benefits in patients whose CSU had not responded to omalizumab, as well as those experiencing severe angioedema.

Angioedema involves swelling beneath the skin and can occur alongside chronic spontaneous urticaria.

Among patients with angioedema at baseline, complete resolution was achieved by 62.7% to 74.3% of those receiving barzolvolimab, compared with approximately 33% of patients receiving placebo.

The findings indicate that the treatment’s effects extended to patient groups with more difficult-to-manage disease.

Safety Profile Consistent With Earlier Studies

Barzolvolimab was reported to be well tolerated through 24 weeks of treatment.

According to Celldex, its safety profile remained consistent with findings from previous Phase 2 studies.

The company did not provide detailed adverse-event rates in the topline information.

Both EMBARQ-CSU trials remain ongoing, with patients continuing treatment through Week 52.

FDA Submission Planned for 2027

Celldex plans to submit a Biologics License Application (BLA) for barzolvolimab to the US Food and Drug Administration in 2027.

The planned submission follows the positive Week 12 efficacy results and subsequent Week 24 findings from the two Phase 3 trials.

Barzolvolimab remains an investigational treatment, and its potential approval will depend on regulatory review of the complete clinical data.

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