Dive Brief:
- Celldex shares sank 13% in early trading Tuesday as investors focused on safety concerns for a medicine that the drugmaker says can transform treatment of a debilitating skin disease.
- The company on Tuesday released results from two successful Phase 3 studies of the drug, barzolvolimab, in patients with a condition called chronic spontaneous urticaria that causes hives and severe itching, burning or swelling. But some investors keyed in on two cases of anaphylaxis in one of the barzolvolimab-dosed groups.
- Celldex downplayed concerns about the drug’s safety, with CEO Anthony Marucci telling analysts on a conference call that the incidence was “extremely low” among about 2,400 patients that have been treated overall. In its press release, the company said barzolvolimab was well-tolerated and displayed a favorable safety profile.
Dive Insight:
Barzolvolimab is the centerpiece of Celldex’s transformation from an oncology company to one focused on immunology. After several research failures in cancer, Celldex turned to barzolvolimab as a new way to treat conditions such as urticaria by driving down counts of “mast” cells implicated in hives. Early tests showed it might be faster-acting, more potent and more durable than current therapies.
At least one analyst said Celldex’s theory has now been proven. “We’d pound the table that Celldex’s efficacy looks to be the best Phase 3 data set we’ve seen across all pivotal studies,” Cantor Fitzgerald analyst Kristen Kluska wrote in a note to clients. Safety, meanwhile, “appears favorable to other biologics that currently produce billions of dollars in revenue,” she wrote.
While it’s hard to predict exactly how the Food and Drug Administration will act on the anaphylaxis cases, Stifel analyst Alex Thompson wrote in a note to clients that he’s optimistic. He noted that top medicines including Dupixent have warnings about anaphylaxis and said he still expects “meaningful sales” for barzolvolimab even if it gets a boxed warning and becomes relegated to last-line usage.
Kluska, meanwhile, forecasts that peak sales of the medicine will reach $4.8 billion. Celldex plans to develop the drug for other uses as well and is already testing it in three different indications other than chronic spontaneous urticaria.
In the two new studies, researchers enrolled almost 2,000 patients who didn’t respond well enough to typical antihistamine therapies. In the initial phase, participants were split into three groups, randomly assigned to either get a placebo or one of two dosing regimens of barzolvolimab. After all the patients had been treated for 24 weeks, researchers performed the analysis released Tuesday. The study is designed to follow patients for a year.
Celldex said the results were “unparalleled” for patients with chronic spontaneous urticaria, showing a significant reduction in urticaria activity — the study’s main objective — as well as success in key secondary endpoints. In the two groups that received barzolvolimab, about half of patients had a complete response — total absence of itch and hives — after 24 weeks, compared with between 15% and 18% in the placebo group.
Still, analysts said they are looking closely at the drug’s safety. One concern that has persisted about barzolvolimab is whether the drug might reduce levels of neutrophils too much, potentially leaving patients vulnerable to infections. Other than neutropenia, the most common side effects are changes in hair color and skin pigmentation.
The anaphylaxis cases were detailed in a slide listing adverse events. One occurred after a dose of placebo, while two occurred in one of the barzolvolimab-dosed groups. Physicians may just opt to give the first dose of the medicine in their clinics to monitor for potential issues, Kluska said.
Celldex said it plans to file for FDA approval of barzolvolimab next year.
