NEW YORK – according to an expert evaluating current approaches at the Skin of Color Update 2023.
“As dermatologists, prurigo nodularis is one of the most severe diseases we treat, said Shawn G. Kwatra, MD, director of the Johns Hopkins Itch Center, Baltimore. Now with one approved therapy and more coming, “it offers one of the most important opportunities we have to dramatically improve someone’s entire life.”
Ted Bosworth/MDedge News
Dr. Shawn G. Kwatra
Prior to the September 2022 approval of dupilumab for the treatment of prurigo nodularis (the first treatment approved for this indication), Dr. Kwatra said that the limited options for control of pruritus made him anxious. Prurigo nodularis is characterized by highly itchy nodules that can produce symptoms patients describe as unbearable.
Itch typically severe
On a scale for which 10 represents the worst itch imaginable, scores of 8 or greater are not unusual, according to Dr. Kwatra. Nodules on the trunk and the extensor surfaces of the arms and legs are characteristic, but the persistent itch is the immediate target of treatment once the diagnosis is made. For that reason, he urged clinicians to be familiar with the presentation in patients with darker skin types to reduce time to treatment.
In addition to the difficulty of seeing the characteristic red that is typical of erythema in lighter skin, patients with darker skin types tend to have larger nodules that might vary in shape relative to lighter skin types, Dr. Kwatra said. Given that the presentation of prurigo nodularis is highly heterogeneous even among the same skin types, the nuances in patients with darker skin can be that much more confusing for those without prior experience.
Among Blacks in particular, the nodules in some cases “can be huge,” he added. “They can almost look like keloids due to their thickened and fibrotic appearance.”
Phenotypes appear to be racially linked
In Black patients, the appearance can vary enough relative to lighter skin individuals, that “there seems to be something a little bit different going on,” he said, and this is, in fact, supported by a cluster analysis of circulating biomarkers reported by Dr. Kwatra and colleagues in 2022, in the Journal of Investigative Dermatology.
In that study, the biomarker profile distinguished two distinct groups. Whites were more common in a cluster with relatively low expression of inflammatory markers (cluster 1), while Blacks were more common in a cluster with an inflammatory plasma profile (cluster 2), with higher relative expression of multiple cytokines, C-reactive protein, eosinophils, and other markers of up-regulated inflammation.
In addition to a lower rate of myelopathy in cluster 2 than cluster 1 (18% vs. 67%; P = .028), patients in cluster 2 had a significantly worse itch than those in cluster 1 on the Numeric Rating Scale for itch and a significantly lower quality of life based on the Dermatology Life Quality Index score.
Other work at Dr. Kwatra’s center that is based on genetic sequencing has provided evidence that Blacks – and Asians to a lesser extent – are predisposed genetically to develop nodules, perhaps explaining why the nodules tend to be larger than those seen in Whites.
The significance of the evidence that prurigo nodularis is associated with a more up-regulated inflammatory profile in Blacks than in Whites is that they might be particularly likely to respond to dupilumab or other targeted immunomodulating therapies that are in development, according to Dr. Kwatra. Although he did not provide data on response by race, he did provide several case examples of complete itch control following dupilumab therapy in Black patients.
In his experience, high levels of blood eosinophils and other inflammatory markers are predictors of response to dupilumab regardless of skin type, but he expressed concern that time to diagnosis is sometimes longer in Black patients if the nuances of disease expression are not appreciated.
For treating prurigo nodularis in Blacks as well as Whites, Dr. Kwatra suggested that clinicians stay current with what he predicted will be a growing array of treatment options. He did not discuss nemolizumab, an interleukin-31 receptor alpha antagonist. Soon after the meeting, results of a phase 3 trial of nemolizumab in patients with moderate to severe prurigo nodularis were published in the New England Journal of Medicine. (Dr. Kwatra is the lead author of the study but did not specifically discuss this treatment at the meeting.)
In the international placebo-controlled trial, called OLYMPIA 2, treatment was associated with a significant reduction in the signs and symptoms of prurigo nodularis, including reductions in itch, at 16 weeks, although only 4% of patients in the study were Black.
Given the expanding array of therapies, the message of considering prurigo nodularis in Black patients in order to accelerate the time to diagnosis is timely, Andrew F. Alexis, MD, MPH, professor of clinical dermatology and vice-chair for diversity and inclusion for the department of dermatology, Weill Cornell Medicine, New York.
“Current studies suggest a higher prevalence and greater severity of prurigo nodularis among Black patients compared to White patients,” said Dr. Alexis, agreeing with Dr. Kwatra. Referring to evidence that Blacks might mount a greater inflammatory response to prurigo nodularis than Whites, Dr. Alexis called for “a better understanding of the pathomechanisms” of this disease in order “to address unmet needs and reduce disparities for our diverse population of patients who suffer from prurigo nodularis.’
Dr. Kwatra reported financial relationships with AbbVie, Amgen, Arcutis, ASLAN, Cara, Castle Biosciences, Celldex, Galderma, Incyte, Johnson & Johnson, LEO pharma, Novartis, Pfizer, Regeneron, and Sanofi.