Celldex Therapeutics has unveiled 52-week results from a mid-stage study of its anti-KIT drug in chronic hives, raising anticipation for ongoing registrational studies.
But the company’s shares $CLDX were down by as much as 27% Wednesday, right after the company’s announcement, due to its adverse event data.
The drug, dubbed barzolvolimab, is in a pair of Phase 3 trials in chronic spontaneous urticaria (CSU) following positive topline Phase 2 data announced in February. Some Wall Street analysts have said Celldex could challenge Novartis’ remibrutinib, which has already completed its registrational studies.
Celldex’s latest results show 71% of 52 CSU patients dosed with 150 mg barzolvolimab every four weeks had a complete response, defined as no itch or hives, at 52 weeks. In the cohort of 51 patients given 300 mg every eight weeks, just over half of them had a complete response. Celldex’s Wednesday release did not mention p-values.
“We believe this data set is a landmark event for the barzolvolimab program and for the treatment of CSU,” Celldex CMO Diane Young said in a statement. The candidate is being investigated in patients struggling with symptoms despite antihistamine treatment. The responses were seen regardless of patients’ prior exposure to Novartis and Genentech’s monoclonal antibody Xolair.
For context, almost 56% of patients dosed twice daily with Novartis’ BTK inhibitor achieved a complete response at 52 weeks in a Phase 2b extension trial of the drug in CSU. After reporting positive long-term Phase 3 data in May, the drugmaker has said it will file remibrutinib with regulatory agencies in the second half of the year.
But at 52 weeks, Celldex’s candidate has a higher incidence of neutropenia (17%) versus its earlier 16-week data (9%). Neutropenia was a big concern for investors going into the Phase 2 trial, TD Cowen analysts said in February.
Celldex said that neutrophil counts didn’t drop further with continued dosing in the latest Phase 2 data, and there was no link between neutropenia and infections.
The Wednesday release did not mention concerns with anaphylaxis. The company said around 8% of patients in the 150 mg arm and 13% in the 300 mg arm discontinued treatment due to an adverse event.
The company reported topline Phase 2 results in February that showed three doses, including the lowest dose of 75 mg, met the primary endpoint of mean change in urticaria activity score 7 (UAS7) at 12 weeks. At the time, this result was described by Cowen analysts as “superb.”
The two identical Phase 3 studies of barzolvolimab in CSU, which were initiated in July, are aiming to enroll 915 patients each and will test 150 mg and 300 mg doses. Both trials are using the same primary endpoint as the Phase 2.
Barzolvolimab is also in development for prurigo nodularis, atopic dermatitis and chronic inducible urticaria. Earlier this month, GlobalData analysts said barzolvolimab could achieve $874 million in US sales by 2039.
Editor’s note: This story was updated to add further context.