Baseline Body Surface Area May Drive Optimal Baricitinib Response

Doug Brunk

January 11, 2021

Patients with moderate to severe atopic dermatitis (AD) affecting between 10% and 50% of their body surface area (BSA) account for the majority of responders to baricitinib 2 mg, results from an analysis of phase 3 data showed.

"This proposed clinical tailoring approach for baricitinib 2 mg allows for treatment of patients who are more likely to respond to therapy and rapid decision on discontinuation of treatment for those who are not likely to benefit from baricitinib 2 mg," Eric L. Simpson, MD, said during a late-breaking abstract session at the Revolutionizing Atopic Dermatitis virtual symposium.

Baricitinib is an oral, reversible and selective Janus kinase 1/JAK2 inhibitor that is approved in Europe for the treatment of moderate to severe AD in adults who are candidates for systemic therapy. In the United States, it is approved for treating rheumatoid arthritis, and is currently under Food and Drug Administration review in the United States for AD.

For the current analysis, Simpson, professor of dermatology at Oregon Health & Science University, Portland, and colleagues set out to identify responders to baricitinib 2 mg using a tailored approach based on baseline BSA affected and early clinical improvement in the phase 3 monotherapy trial BREEZE-AD5. The trial enrolled 440 patients: 147 to placebo, 147 to baricitinib 1 mg once daily, and 146 to baricitinib 2 mg once daily. The primary endpoint was Eczema Area and Severity Index (EASI)–75 at week 16.

"Understanding which patients can benefit most from this treatment was our goal," Simpson said. "By tailoring your therapy, you can significantly improve the patient experience, increase the cost-effectiveness of a therapy, and you can ensure that only patients who are likely to benefit are exposed to a drug."

The researchers used a classification and regression tree algorithm that identified baseline BSA as the strongest predictor of EASI-75 response at week 16. A BSA cutoff of 50% was established as the optimal cutoff for sensitivity and negative predictive value. Results for EASI-75 and Validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) scores of 0 or 1 were confirmed using a BSA of 10%-50% at baseline to predict response, compared with a BSA or greater than 50% at baseline.

Sensitivity analyses revealed that about 90% of patients with an EASI-75 response were in the BSA 10%-50% group. Conversely, among patients with a BSA greater than 50%, the negative predictive value was greater than 90%, "so there’s a 90% chance you’re not going to hit that EASI-75 at week 16 if your BSA is greater than 50%," Simpson explained. "The same holds true for vIGA-AD, so that 50% cutoff is important for understanding whether someone is going to respond or not."

On the EASI-75, 38% of patients in the BSA 10%-50% group responded to baricitinib at week 16, compared with 10% in the BSA greater than 50% group. A similar association was observed on the vIGA-AD, where 32% of patients in the BSA 10%-50% group responded to baricitinib at week 16, compared with 5% in the BSA greater than 50% group.

When stratified by early response assessed at week 4, based on a 4-point improvement or greater on the Itch Numeric Rating Scale, 55% of those patients became EASI-75 responders, compared with 17% who were not. A similar association was observed by early response assessed at week 8.

"Due to the rapid onset of response, clinical assessment of patients after 4-8 weeks of initiation of baricitinib 2 mg treatment provided a positive feedback to patients who are likely to benefit from long-term therapy," Simpson said. "This analysis may allow for a precision-medicine approach to therapy in moderate to severe AD."

The study was supported by Eli Lilly, and was under license from Incyte. Simpson reported serving as an investigator for and consultant to numerous pharmaceutical companies.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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