Jonathan Silverberg, MD, PhD, MPH
The Janus kinase (JAK) family has become a popular target for novel drug development. There are four JAK subunits, JAK1, JAK2, JAK3, and TYK2, each playing different roles in vital immunologic, hematologic, and homeostatic functions. A wide array of topical JAK-inhibitors has been or are currently being investigated for the treatment of AD, each with different profiles of selectivity across the JAK family.
Ruxolitinib is a preferential JAK1 and JAK2 inhibitor. Oral ruxolitinib is currently approved for the treatment of myelofibrosis. Topical ruxolitinib cream is also approved in the United States for the treatment of mild-to-moderate AD and, more recently, vitiligo.
Blauvelt and colleagues published the findings from a post hoc analysis of data related to itch responses from two randomized, double-blind, vehicle-controlled, phase 3 studies of patients with mild-to-moderate AD. Topical ruxolitinib applied twice daily led to a significant increase in the proportion of patients achieving at least a 2-point or 4-point reduction in Peak Pruritus Numeric Rating Scale (PP-NRS) within 12 hours of initial application and continued improvements out to week 8. Patients treated with ruxolitinib cream were also significantly more likely to achieve an itch-free state and faster reductions in itch compared with vehicle. Rapid improvement of itch is an important feature for any topical therapy that may be used as needed for AD flares.
Brepocitinib is a preferential JAK1 and tyrosine kinase 2 inhibitor. Oral brepocitinib is currently under investigation for several immune-mediated disorders, including dermatomyositis and lupus. Topical brepocitinib cream was also studied in a randomized, double-blind, vehicle-controlled, phase 2 study of patients with mild-to-moderate AD. Brepocitinib cream applied daily or twice daily led to significant decreases in the Eczema Area and Severity Index (EASI), increases in the proportion of patients who achieved Investigator Global Assessment (IGA) scores of clear or almost clear, EASI-75 responses, and 2-point or 4-point reductions in PP-NRS. Overall, topical brepocitinib was well tolerated. Though more studies are needed, topical brepocitinib may become an important addition to our toolbox for managing AD and perhaps other chronic inflammatory skin diseases.
Let's move along to yet another novel mechanism studied in AD: ectoine. Ectoine is a naturally derived chemical from some bacteria that can act as an osmolyte and protect organisms from osmotic stress. It is used in some skin care products because it can protect against xerosis and ultraviolet exposure. Alexopoulos and colleagues published the results of a randomized, single-blind, vehicle-controlled study of a novel cream containing 1% ectoine and 0.1% hyaluronic acid (EHA) in children with mild-to-moderate AD. At week 4, application of EHA cream led to significant decreases in SCORing AD (SCORAD) and IGA scores compared with vehicle cream as well all secondary outcome measures. EHA cream was well-tolerated overall, with most adverse events being cutaneous and mild.
All of these topical agents were studied as "reactive" therapies, ie, to be applied to active AD lesions. It would be nice to have approaches that can also prevent AD. Ní Chaoimh and colleagues published findings from the STOP AD trial that examined whether routine application of emollients in the first 8 weeks of life can prevent AD at age 12 months. They found that early emollient use resulted in significantly lower incidence of AD and similar rates of skin infections at age 12 months. Previous studies found mixed results regarding the efficacy of routine application of emollients in newborns. Though more studies are needed, these results are promising and suggest that early life use of emollients could be a cheap, feasible, and effective option to prevent AD.