Chronic Itch in Older Adults: Workup and Management Advice

WASHINGTON — Immunoglobulin E (IgE) and eosinophils appeared to be reliable biomarkers of type 2 inflammation in chronic pruritus of unknown origin (CPUO) and predictors of a positive response to immunomodulatory therapies, Shawn Kwatra, MD, said at the ElderDerm conference on dermatology in older patients hosted by the GW School of Medicine & Health Sciences.

“We found a few years ago that eosinophils seem to differentiate this group, and now we’re finding that IgE and CBC [complete blood count] differential can help you get a little better sense of who has an immune-driven itch vs something more neuropathic,” said Kwatra, professor and chair of dermatology at the University of Maryland, Baltimore, who founded and directed the Johns Hopkins Itch Center before coming to the University of Maryland in 2023. Not all patients with immune-driven itch will have these biomarkers, “but it’s a helpful tool,” he said.

CPUO is the term that is increasingly being used, he said, to describe intense, chronic pruritus without primary skin lesions or rashes and without any known systemic cause. It becomes more common as people get older and is sometimes debilitating. The initial evaluation should be kept “simple and straightforward,” he advised, with heightened concern for underlying malignancy in those who present with an itch of less than 12 months’ duration.

Biologics, JAK Inhibitors: Case Reports, Ongoing Research 

Research conducted by Kwatra and Jaya Manjunath, a fourth-year medical student at The George Washington University, Washington, DC, documented higher levels of Th2-associated cytokines and inflammatory markers in patients with CPUO who had elevated IgE or eosinophil levels, or both than in patients with itch who had low IgE and eosinophil levels. The patients with higher levels also had a greater response to off-label treatment with immunomodulatory therapy.

“Multiple Th2-related inflammatory markers, like IL [interleukin]-5 and eotaxin-3, were reduced after dupilumab” in patients who responded to the therapy, said Manjunath, who co-presented the meeting session on chronic itch with Kwatra. Other changes in the plasma cytokine profile included a reduction in the serum level of thymus and activation-regulated chemokine, which is a biomarker for atopic dermatitis. The research is under review for publication.

Meanwhile, a phase 3 trial (LIBERTY-CPUO-CHIC) of dupilumab for CPUO is currently underway, Kwatra noted. Investigators are randomizing patients with severe pruritus (Worst Itch Numeric Rating Scale [WI-NRS] ≥ 7) to dupilumab or placebo for 12 or 24 weeks.

In one of several cases shared by Kwatra and Manjunath, a 71-year-old Black woman with a 6-month history of generalized itch (WI-NRS = 10) and a history of type 2 diabetes, hypertension, and chronic kidney disease was found to have elevated eosinophil levels and a negative malignancy workup. Previous therapies included antihistamines and topical steroids. She was started on a 600-mg loading dose of subcutaneous dupilumab followed by 300 mg every 14 days. At the 2-month follow-up, her WI-NRS score was 0.

Because “dupilumab is off label right now for this form of itch, oftentimes our first line is methotrexate,” Kwatra said. Patients “can have a good response with this therapeutic.”

He also described the case of a 72-year-old Black woman with total body itch for 2 years (WI-NRS = 10) and a history of seasonal allergies, thyroid disease, and hypertension. Previous therapies included prednisone, antihistamines, topical steroids, and gabapentin. The patient was found to have high IgE (447 kU/L) and eosinophil levels (4.9%), was started on methotrexate, and had an itch score of 0 at the 8-month follow-up.

JAK inhibitors may also have a role in the management of CPUO. A phase 2 nonrandomized controlled trial of abrocitinib for adults with prurigo nodularis (PN) or CPUO, published in JAMA Dermatology in June, showed itch scores decreased by 53.7% in the CPUO group (and 78.3% in the PN group) after 12 weeks of treatment with oral abrocitinib 200 mg daily. Patients had significant improvements in quality of life and no serious adverse events, said Kwatra, the lead author of the paper.

One of these patients was a 73-year-old White man who had experienced total body itch for 1.5 years (predominantly affecting his upper extremities; WI-NRS = 10) and a history of ascending aortic aneurysm, hypertension, and hyperlipidemia. Previous failed therapies included dupilumab (> 6 months), topical steroids, tacrolimus, and antihistamines. Labs showed elevated IgE (456 kU/L) and eosinophil levels (11.7%). After 12 weeks of treatment with abrocitinib, the WI-NRS decreased to 2.

PD-1 Inhibitors As a Trigger

Chronic pruritus caused by the anticancer PD-1 inhibitors is becoming more common as the utilization of these immune checkpoint inhibitors increases, Kwatra noted. “You don’t see much in the skin, but [these patients have] very high IgE and eosinophils,” he said. “We’ve been seeing more reports recently of utilizing agents that target type 2 inflammation off label for PD-1 inhibitor–related skin manifestations.”

One such patient with PD-1 inhibitor–induced pruritus was a 65-year-old White man with metastatic melanoma who reported a 6-month history of itching that began 3 weeks after the start of treatment with the PD-1 inhibitor pembrolizumab. His WI-NRS score was 10 despite treatment with topical steroids and antihistamines. He had a history of psoriasis. Labs showed elevated IgE (1350 kU/L) and eosinophil levels (4.5%). At a 4-month follow-up after treatment with off-label dupilumab (a 600-mg subcutaneous loading dose followed by 300 mg every 14 days), his WI-NRS score was 0.

In a paper recently published in JAAD International, Kwatra, Manjunath, and co-investigators reported on a series of 15 patients who developed chronic pruritus following an immune stimulus exposure, including immunotherapy and vaccination. Most immunotherapy-treated patients experienced pruritus during treatment or after 21-60 days of receiving treatment, and the patients with vaccine-stimulated pruritus (after Tdap and messenger RNA COVID-19 vaccination) developed pruritus within a week of vaccination.

In addition to the elevated levels of IgE and eosinophils, plasma cytokine analysis showed elevated levels of IL-5, thymic stromal lymphopoietin, and other Th2-related cytokines and inflammatory markers in patients with immune-stimulated pruritus compared with healthy controls, Manjunath said at the meeting.

When a Malignancy Workup Becomes Important

The initial part of any diagnostic workup for CPUO should include CBC with differential, liver function tests, renal function tests, and thyroid function testing, said Kwatra, referring to a diagnostic algorithm he developed, which was published as part of a CME review in the Journal of the American Academy of Dermatology in 2022.

Then, as indicated by risk factors in the history and physical, one could order other tests such as HIV serology, hepatitis B/C serologies, bullous pemphigoid testing, chest x-rays, evaluation for gammopathies, stool examination for ova and parasites, or heavy metal testing. “Do you do everything at once? We like to keep it straightforward,” Kwatra said. “Depending on the patient’s risk factors, you could order more or less.”

A malignancy workup should be strongly considered in patients whose itch duration is less than 12 months — and especially if the duration is less than 3 months — with an emphasis on cancers more frequently associated with itch: Hematologic and hepatobiliary cancers. This is “when concern should be heightened…when there should be a lower threshold for workup,” he said.

The 12-month recommendation stems from a Danish cohort study published in 2014 that demonstrated a twofold increased incidence of cancer among patients with pruritus in the first 3 months after the diagnosis of pruritus. The 1-year absolute cancer risk was 1.63%.

Other risk factors for underlying malignancy or malignancy development in patients with CPUO include age older than 60 years, male sex, liver disease, and current or prior smoking, according to another study, noted Kwatra.

Kwatra disclosed that he is an advisory board member/consultant for Pfizer, Regeneron, Sanofi, and other companies and an investigator for Galderma, Incyte, Pfizer, and Sanofi. Manjunath served as the codirector of the ElderDerm conference.