The current study comprised patients aged 12-75 years who had a 6-month or longer history of chronic idiopathic urticaria, the presence of hives associated with itching for at least 8 consecutive weeks at any time prior to enrollment (despite H1-antihistamine use), a UAS7 of 16 or more during a 7-day period, a weekly itch-severity score of at least 8, a score of at least 4 on the UAS on at least one of the screening-visit days, and receipt of a licensed dose of a second-generation H1-antihistamine for at least 3 consecutive days immediately prior to the screening visit. Those with a clearly defined underlying cause for their symptoms were excluded. The doses evaluated in this study were based on a prior dose-ranging study, which showed no additional benefit with doses over 300 mg, the investigators said.
Patients continued to receive stable doses of H1-antihistamines throughout the 12-week treatment period, and were permitted to use diphenhydramine as a rescue medication.
Omalizumab was well tolerated in this study, with a similar number of adverse events occurring across the treatment groups. Serious adverse events occurred more often in the 300-mg group, with 6% of patients in that group experiencing a serious adverse event, compared with 3% of patients in the placebo group, and 1% of patients in the 150-mg and 75-mg groups, but the events were not considered to be related to the study drug.
The duration of response, however, was limited, as noted during a 16-week observation period following the initial 12-week treatment period.
Although the weekly itch-severity scores did not return to baseline during follow-up, they did increase to the levels seen in the placebo group.
The findings are nonetheless encouraging, Dr. Kaplan said, noting that this disease, which can have dramatic adverse effects on quality of life, is not uncommon, and can be difficult to treat, with about half of all patients failing to respond to standard therapy with high dose antihistamines. Alternate treatments used to treat the disease, including steroids and cyclosporine, can be effective, but can be highly toxic, he said.
"For refractory patients we have nothing that matches (omalizumab’s) combination of this kind of efficacy with low side effects, so many of us in the field kind of view this as a game changer for the patients," he said.
This study was sponsored by Genentech and Novartis Pharma. Several study authors made disclosures. A complete list of these disclosures is available with the full text of the article at NEJM.org.