Durable Responses Seen With Barzolvolimab in CSU Trial

AMSTERDAM — Patients with chronic spontaneous urticaria (CSU) experienced early and sustained improvements in symptom scores on treatment with barzolvolimab, during the 52-week follow-up of an ongoing phase 2 study.

Moreover, in the study, barzolvolimab, an anti-KIT monoclonal antibody that inhibits the activation of and depletes mast cells, induced comparable responses in a subset of patients who had taken omalizumab, an anti-immunoglobulin E monoclonal antibody approved by the US Food and Drug Administration for treating CSU.

The findings were presented on September 25 at the annual European Academy of Dermatology and Venereology (EADV) 2024 Congress. Barzolvolimab is being developed by Celldex Therapeutics.

“Barzolvolimab treatment resulted in rapid, profound, and durable improvement in UAS7 [weekly Urticaria Activity Score 7],” said presenter Martin Metz, MD, professor of dermatology, Institute of Allergology, Charité-Universitätsmedizin Berlin, Berlin, Germany, “with a deepening of response over 52 weeks in patients with antihistamine-refractory CSU.”

“Similar robust improvement was seen in patients previously treated with omalizumab, including refractory patients,” he added.

Because barzolvolimab was well tolerated over the course of the follow-up period, Metz said, it “has the potential to be an important new treatment option,” noting that patients are now being enrolled in global phase 3 studies of barzolvolimab.

Sustained Symptom Relief

Ana M. Giménez-Arnau, MD, PhD, associate professor of dermatology, Autonomous University and Pompeu Fabra University, Barcelona, Spain, told Medscape Medical News that the results are important, as they showed people who switched from placebo to the active drug also saw a long-term benefit.

What is “remarkable” about barzolvolimab, continued Giménez-Arnau, who was not involved in the study, is that it is the first drug to target the KIT receptor on mast cells and interfere with stimulating growth factors, thus making the cells that drive the development of CSU “disappear.”

The study included three different barzolvolimab regimens, with the 150-mg dose every 4 weeks and the 300-mg dose every 8 weeks achieving similar results, noted Giménez-Arnau.

For her, there are important questions to answer around the pharmacokinetic and pharmacodynamic profiles of the two regimens that remain, but she underlined that for the patient, the choice of regimen could have an impact on their quality of life.

“If we give 300 mg every 8 weeks,” she said, it appears “you can achieve disease control” while halving the frequency of subcutaneous injections.

She said that it would be “interesting to know” if 300 mg every 8 weeks is given as two 150-mg injections every 2 months or one 300-mg injection. If it is the former, Giménez Arnau said, “This is potentially an important benefit for the patient.”

Sustained Benefits at 1 Year

The study enrolled 208 patients with antihistamine-refractory CSU at sites in 10 countries, randomizing them to one of four arms: Subcutaneous injections of barzolvolimab 75 mg or 150 mg every 4 weeks, 300 mg every 8 weeks, or placebo every 4 weeks.

The mean age in each arm was between 42 and 47 years, and around 75% were women. Across the arms, 64%-76% had severe disease, as measured on the UAS7, at a mean score of 30.0-31.3. Around 20% had previously been treated with omalizumab.

Patients were treated for 16 weeks, during which time they completed daily and weekly diaries and attended six clinic visits at weeks 0, 2, 4, 8, 12, and 16. Results from the trial published earlier this year demonstrated that both the regimens (150 mg every 4 weeks and 300 mg every 8 weeks) achieved clinically meaningful and statistically significant improvement in UAS7, the primary endpoint, vs placebo at 12 weeks.

Participants in the barzolvolimab 75 mg and placebo arms were then randomized to receive barzolvolimab 150 mg every 4 weeks or 300 mg every 8 weeks, and those who had been in the 150-mg and 300-mg treatment arms continued with that treatment for a further 36 weeks. (The remaining patients have been continued on a further 24-week follow-up, but the data are not yet available.)

By the 52-week follow-up, 25% of patients who started in each of the barzolvolimab arms had discontinued treatment, as well as 16% first randomized to the placebo arm.

Metz reported that the improvements in UAS7 scores, observed as early as week 1, were sustained through week 52 in patients in both the ongoing 150-mg and 300-mg arms. Patients who initially started in the placebo and the barzolvolimab 75-mg groups caught up with those who had started on the higher doses, so that by week 52, there were no significant differences in urticaria activity, hives, or itch scores between the arms.

By week 52, the proportion of patients achieving well-controlled disease, defined as a UAS7 score ≤ 6, was 73.7% in the barzolvolimab 150 mg every 4-week arm and 68.2% in the 300 mg barzolvolimab every 8-week arm.

Notably, just 12.8% of patients in the placebo arm had achieved well-controlled CSU by week 16, but after switching to barzolvolimab 150 mg every 4 weeks or 300 mg every 8 weeks, 63% reached that target at week 52.

“Maybe even more striking and very interesting to look at,” said Metz, was the complete control of symptoms, meaning “not one single wheal and no itch.” By week 52, 52% of those on 300 mg every 8 weeks and 71.1% of those on 150 mg every 4 weeks had a complete response, with no itch/hives (UAS7 of 0).

Importantly, complete responses with barzolvolimab were observed early and were sustained or improved to week 52, Metz said, with, again, placebo and former barzolvolimab 75 mg patients catching up with those who started on 150 mg every 4 weeks and 300 mg every 8 weeks once they switched at week 16.

“This is the best data for chronic spontaneous urticaria that we have so far seen,” he said, adding that the responses were seen regardless of prior experience with omalizumab.

Changes in Hair Color, Skin Pigmentation

As for safety, during the first 16 weeks, 66% of those on active treatment and 39% on placebo experienced at least one adverse event. There were no treatment-related serious adverse events, compared with two among those who received treatment for the full 52 weeks.

The most common adverse events with active treatment were hair color changes (14% in the first 16 weeks and 26% among those treated for the full 52 weeks), neutropenia/reduced neutrophil count (9% in the first 16 weeks and 17% among those treated for the full 52 weeks), and skin hypopigmentation (1% in the first 16 weeks, 13% among those treated for the full 52 weeks, and 19% among those who switched from placebo to active treatment at 36 weeks). Urticaria was reported by 10% among patients on active treatment and 10% among those on placebo in the first 16 weeks, and by 15% of those treated for the full 52 weeks.

In the post-presentation discussion, Metz explained that the hypopigmentation appears to start around the hair follicle and is diffuse, so tends to look like vitiligo.

He suggested that the melanocytes around the hair follicle “seem to be the ones that are more stressed, maybe because of the hair follicle cycling,” adding that the effect is reversible and does not appear to be dose dependent.

The study was funded by Celldex Therapeutics. Metz declared relationships with AbbVie, ALK-Abelló, Almirall, Amgen, argenx, AstraZeneca, Astria, Attovia Therapeutics, Celldex, Celltrion, Escient Pharmaceuticals, Galen, Galderma, GSK, Incyte, Jasper, Lilly, Novartis, Pfizer, Pharvaris, Regeneron, Sanofi, Teva, Third Harmonic Bio, and Vifor.