TARC Identifies Poor Dupilumab Response in Atopic Dermatitis

Serum thymus and activation-regulated chemokine (TARC) levels may identify some patients with atopic dermatitis that is resistant to therapy with dupilumab, researchers say.

Such patients might need more intensive treatment or longer treatment with dupilumab, said Yoko Kataoka, MD, head of dermatology at Osaka Habikino Medical Center, in Osaka, Japan.

Kataoka presented the finding at the International Society of Atopic Dermatitis (ISAD) 2021 Annual Meeting.

In contrast to many other countries, including the United States, testing of serum TARC levels is reimbursable and is commercially available for monitoring atopic dermatitis in Japan.

TARC levels can indicate which patients are most likely to experience flares in symptoms, even after the signs and symptoms of the disease have resolved following treatment with topical corticosteroids or cyclosporine.

With these treatments, some Japanese clinicians monitor TARC levels to see which patients should continue therapy after symptoms have disappeared, Kataoka told Medscape Medical News. “Once the skin lesion disappears [with] topical treatment, there are still remnants. When we stop treatment, the remnant flares,” she said.

To see whether the monitoring of TARC levels could work the same way with regard to dupilumab, which is a newer therapy, Kataoka and her colleagues measured the TARC levels and determined Eczema Area and Severity Index (EASI) scores of 93 people with atopic dermatitis at baseline and after 4 months of treatment with dupilumab.

Thirty-four of the patients experienced improvement of ≥90% (EASI-90); 34 improved by 75% to 90% (EASI-75/90), and 25 improved by <75% (EASI <75).

Serum TARC levels decreased significantly in all three groups over the 4 months. TARC levels did not differ significantly among the groups.

Among the 93 patients, there was not a close correlation between the EASI score and TARC levels, either at baseline (r = 0.348, P < .01) or at 4 months (r = .355, P < .01).

The correlation for most of the subgroups was weak as well. For the EASI <75 group, the data were as follows: at baseline, r = .20, P = .32; after 4 months, r = .20, P = .31.

For the EASI-75/90 group, the correlation was significant at baseline (r = 0.60, P < .01), but at 4 months, it had dropped (r = -0.31, P = 0.86).

For the EASI-90 group, the data were as follows: at baseline, r = 0.15, P = .20; at 4 months, r = – 0.14, P = .23.

On the basis of these results, TARC levels would not be as useful in measuring the effectiveness of dupilumab as it is with older treatments, Kataoka said.

The researchers did identify a subgroup of patients for whom TARC levels provided potentially useful information. For seven patients in the EASI <75 group, serum TARC levels were >1000 pg/mL after 4 months.

Some of these patients had the most severe atopic dermatitis, with long clinical histories. They needed treatments such as cyclosporine in addition to dupilumab. TARC levels at baseline might be useful to identify these patients, said Kataoka.

Although the use of TARC levels in this study was not effective for identifying patients who would respond well and those who would respond less well to dupilumab overall, TARC levels still provide useful information for evaluating patients, said Lawrence Eichenfield, MD, professor of dermatology and pediatrics at the University of California, San Diego.

In particular, TARC levels may help determine which patients are the best candidates for which therapies. “They may be useful in the future to help us assess clinical response and/or speed of response potentially to the different systemic agents as we start to hit an age of markedly dissimilar targets of therapy,” he told Medscape Medical News.

Kataoka said she would like to study serum TARC levels in patients treated with Janus kinase inhibitors, such as those now in the pipeline for the treatment of atopic dermatitis.

Kataoka has disclosed no relevant financial relationships.

International Society of Atopic Dermatitis (ISAD) 2021 Annual Meeting: Abstract PB3. Presented April 19, 2021.

Laird Harrison writes about science, health and culture. His work has appeared in magazines, newspapers , and online publications. He is at work on a novel about alternate realities in physics. Harrison has taught writing at San Francisco State University, UC Berkeley Extension and the Writers Grotto. Visit him at lairdharrison.com or follow him on Twitter: @LairdH.

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