SCOTTSDALE, ARIZ. – The phosphodiesterase-4 inhibitor crisaborole was well tolerated over 6 to 12 months, yielding no major safety signals during a multicenter, open-label extension study of patients with mild-to-moderate atopic dermatitis.
These safety results held up across age groups and over time, said Dr. Lawrence Eichenfield, a dermatologist at Children’s Hospital, San Diego, and at the University of San Diego School of Medicine. “The majority of treatment-emergent adverse events were considered mild to moderate and not related to treatment. There were no reports of long-term cutaneous reactions, such as atrophy or telangiectasia,” he and his associates added.
Atopic dermatitis has lacked widely accepted treatment options. Despite attempts to educate patients and parents about topical steroids, many are afraid to use them, and topical calcineurin inhibitors have a black box warning for cancer risk. Not surprisingly, therefore, a 2% ointment of crisaborole made headlines in 2015 after meeting its efficacy and safety endpoints in two pivotal phase III trials of patients with mild-to-moderate atopic dermatitis. Based on those results, Anacor Pharmaceuticals filed a new drug application for the novel boron-based small molecule in January 2016.
The pivotal trials lasted just 28 days, so to assess long-term safety, Dr. Eichenfield and his associates enrolled a subgroup of 517 patients aged 2 to 72 years into a single-arm, open-label, 48-week extension study of crisaborole. About 31% of participants had received the control vehicle during the pivotal trials, while the rest had received crisaborole and tolerated it well enough to continue using it. Patients applied crisaborole twice daily during treatment cycles of 28 days, and were evaluated on days 1, 8, and 29 for up to 12 treatment cycles. Patients whose skin became clear or almost clear went off treatment, but they were still assessed for adverse effects at the same frequency.
In all, 396 patients used crisaborole for at least 6 months, and 271 completed 12 months of treatment, the researchers reported at the annual meeting of the Society for Investigative Dermatology. Only nine (1.7%) patients stopped treatment during the extension study because of treatment-emergent adverse effects. A total of 65% of patients had at least one treatment-emergent adverse event during the initial phase III trials, the extension study, or both. These were usually mildly or moderately severe and included nasopharyngitis, upper respiratory infections, cough, and/or fever, all of which were considered unrelated to treatment.
Treatment-related adverse events included flares of atopic dermatitis, burning or stinging at the application site, and application site infection, which affected 3.1%, 2.3%, and 1.2%, respectively, of patients in the extension study. None of these events were considered serious. Notably, 11% of patients experienced atopic dermatitis flares in the original phase III trials, the researchers reported. Patients who could not tolerate crisaborole were excluded from the extension study, which might help explain the lower flare rate (3%) with long-term treatment.
“Crisaborole topical ointment, 2%, demonstrated a favorable long-term safety profile for the treatment of patients aged 2 years and older with mild-to-moderate atopic dermatitis,” the researchers concluded. The Food and Drug Administration accepted the new drug application in March.
Anacor Pharmaceuticals makes crisaborole and funded the study. Dr. Eichenfield has served as an investigator and consultant to Anacor. Three coinvestigators also reported affiliations with Anacor.