Celldex Therapeutics Touts Barzolvolimab Phase III CSU Momentum, Lays Out 2026 Data Catalysts
by Tristan Rich · The Markets DailyCelldex Therapeutics (NASDAQ:CLDX) executives highlighted recent clinical progress and upcoming catalysts during a discussion at the Leerink Partners Global Healthcare Conference, with a major focus on the company’s Phase III program in chronic spontaneous urticaria (CSU) for barzolvolimab.
Execution milestones and upcoming readouts
President and CEO Anthony Marucci described 2025 as “a year of execution,” noting the completion of multiple studies in CSU and chronic inducible urticaria (CIndU) and the initiation of additional Phase III trials. The company said it expects several data releases in 2026, with a sequence of readouts led by prurigo nodularis (PN) in the summer, followed by Phase III CSU data in the fourth quarter, and Phase II atopic dermatitis (AD) data toward the end of the year.
Marucci said the company completed a 52-week therapeutic study in CSU with an additional 20-week follow-up, presenting data through 76 weeks. He called the results “unprecedented,” citing up to a 71% complete response rate at 52 weeks and noting that at 76 weeks—after patients were off drug—41% still had a complete response.
Phase III CSU program: enrollment scale and patient mix
Management emphasized rapid enrollment in its Phase III CSU studies, saying accrual finished six months ahead of schedule and exceeded the targeted level. Celldex reported enrolling 1,939 patients across about 500 sites in 43 countries, which it described as the largest CSU studies conducted in patients who were refractory to antihistamines and included biologic-experienced or biologic-refractory patients.
In terms of the enrolled population, Marucci said 75% of participants were antihistamine-refractory and 25% were biologically experienced or refractory. He also pointed to a notable mix of treating specialties in the U.S.: Celldex said 26% of the overall study was enrolled in the U.S., and within that U.S. subset, 53% of patients were enrolled by dermatologists, which both the moderator and management said was a surprise given the historical perception that CSU is more allergist-driven.
Durability and “disease modification” discussion
Chief scientific officer Tibor Keler discussed a CSU subset analysis focused on durability of response off treatment, following patients with well-controlled disease at 52 weeks out to 76 weeks. He said the company observed a high rate of maintained complete response, and that patients who relapsed did so with mild disease.
Keler also noted pharmacokinetic and biomarker observations, including complete responses persisting even when barzolvolimab levels were below those typically associated with significant KIT suppression, and tryptase levels returning toward normal. Executives said these findings raise the question of whether the therapy could be disease-modifying, while acknowledging there is no standard definition of disease modification in CSU. They added that the durability appears longer than what pharmacokinetics alone would predict and greater than what would be expected from spontaneous remission in a population with a mean disease duration of about seven years.
Dosing strategy, safety expectations, and competitive positioning
Celldex said its Phase III CSU study design incorporates loading doses intended to improve early response. The company is using the same maintenance doses as in Phase II, but with a 300 mg loading dose for the 150 mg every-four-weeks arm and a 450 mg loading dose for the 300 mg every-eight-weeks arm. Management said modeling suggested the loading dose could “smooth” early responses without creating safety concerns, citing experience with similar or higher exposures in other studies, including prior intravenous dosing.
On Phase III expectations, Marucci said the company is aiming for results similar to Phase II and highlighted that the CSU program was powered at 90% to detect a 10-point improvement, including in the refractory population. Chief medical officer Diane Young said the company is looking for a safety profile consistent with Phase II. Marucci added that previously observed neutropenia was transient, while hair lightening and hypopigmentation were described as mild (grade 1) and reversible.
Discussing commercial positioning, Marucci outlined two main entry points based on the company’s interpretation of Phase II data: patients with severe CSU and severe angioedema, and patients who are not fully controlled on existing advanced therapies. He said that in Phase II, 36% of patients had both severe UAS-7 CSU and severe angioedema, with a mean angioedema score of 53 (noting a score of 19 is considered severe), and the company observed strong control of the angioedema score along with quality-of-life improvements and complete responses.
Marucci also commented on the evolving market, saying he had heard the launch of “Rhapsido” was going well and characterizing it as “very XOLAIR-like” in efficacy, while noting it is an oral therapy taken twice daily. He said Celldex views its potential position as distinct, focusing on patients with severe angioedema/severe CSU and as a “second line advanced” option after therapies such as XOLAIR, DUPIXENT, or remibrutinib.
Other pipeline updates: CIndU, PN, AD, and CDX-622
For CIndU, Young highlighted retreatment data presented as a late-breaking poster at EAACI. In the Phase II program, patients could be retreated during follow-up upon recurrence of symptoms, and the company reported that retreatment produced a similar response to initial treatment with a comparable safety profile. Celldex also initiated Phase III studies in symptomatic dermographism (SD) and cold urticaria (ColdU) at the end of December and said it is reusing many CSU sites and the same CRO. In ColdU, Celldex said the primary endpoint is complete response by provocation test, with secondary endpoints including patient-reported outcomes such as itch.
In prurigo nodularis, Keler said the program was prompted by an observed complete response in a CIndU study participant. In a Phase I-B PN study using single-dose intravenous barzolvolimab, the company reported that at the 3 mg/kg dose, 57% of patients achieved at least a four-point reduction in itch at eight weeks, along with lesion healing signals. For the ongoing Phase II PN study, Celldex is using subcutaneous dosing at higher doses than in urticaria, with two active regimens versus placebo (both with 450 mg loading doses followed by either 300 mg every four weeks or 150 mg every four weeks). Enrollment is complete, and the company expects data this summer.
For atopic dermatitis, executives described the readout as more exploratory than PN, citing itch-related neuroimmune mechanisms as part of the rationale. The Phase II AD study is enrolling an all-comer population, and management said a potential commercial positioning would be after DUPIXENT but before JAK inhibitors if efficacy is competitive.
Finally, Celldex briefly discussed CDX-622, which is in Phase I in healthy volunteers and in a proof-of-mechanism asthma study. Executives said the asthma study is a small open-label trial in moderate patients intended to generate pharmacodynamic data on inhibiting TSLP and mast cells, referencing biomarker patterns seen with approved TSLP inhibitors such as TEZSPIRE. The company said it plans to present healthy volunteer data in the third quarter, including multiple ascending dose and subcutaneous dosing results.
About Celldex Therapeutics (NASDAQ:CLDX)
Celldex Therapeutics, Inc is a clinical-stage biopharmaceutical company focused on the discovery and development of targeted immunotherapies for cancer and other serious diseases. The company’s research platforms leverage novel antibody and vaccine technologies designed to engage the patient’s immune system, with a particular emphasis on oncology and neurologic indications. Celldex’s pipeline includes both monoclonal antibodies and biologic agents that seek to modulate immune responses or deliver targeted cytotoxic activity.
Among Celldex’s lead product candidates is glembatumumab vedotin, an antibody–drug conjugate directed against the glycoprotein NMB (gpNMB) for the treatment of certain breast and skin cancers.