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Keytruda treatment may be associated with eruptive keratoacanthomas

Keytruda therapy was associated with eruptive keratoacanthomas in three patients with metastatic squamous cell carcinoma or metastatic melanoma, according to study results published in JAMA Dermatology.

Researchers conducted a case report study of three patients with metastatic skin cancer (mean age, 83 years; two men and one woman) who were treated with Keytruda (pembrolizumab, Merck) and developed eruptive keratoacanthomas (KAs).

One patient had metastatic squamous cell carcinoma, and was previously treated with Erbitux, (cetuximab, Lilly), methotrexate and radiotherapy. The other two patients had metastatic melanoma, with one previously treated with Yervoy (ipilimumab, Bristol-Myers Squibb) and Zelboraf (vemurafenib, Genentech) for 6 months before starting treatment with pembrolizumab. Two of the patients had previously had lichenoid eruptions while receiving only pembrolizumab, which were treated before the appearance of KAs.

The three patients presented with sudden onset of lesions on sun-exposed areas of the extremities after a median of 13 months of pembrolizumab treatment.

“On lesional biopsy, a lichenoid infiltrate was observed in the underlying dermis, predominantly composed of CD3⁺ T cells, scattered CD2O⁺ B cells and relatively few PD-1⁺ (programmed cell death 1-positive) T cells, an immunophenotypic pattern also observed in other cases of ani-PD-1-induced lichenoid dermatitis,” the researchers wrote.

The patients were treated with clobetasol ointment — applied every other day until the lesions cleared — and intralesional triamcinolone. Two of the patients had open superficial cryosurgery.

The patients had complete resolution of the lesions after 1 month of therapy and remained free of new lesions during follow-up.

Pembrolizumab treatment was continued in all patients, with complete response of primary cancers reported.

“We report the first three cases to our knowledge of eruptive KAs associated with the use of pembrolizumab,” the researchers concluded. “In all three patients, eruptive KAs were controlled with conservative management … allowing patients to continue therapy with pembrolizumab.

“The inflammatory infiltrate seen on the KA biopsy specimens and the complete response to corticosteroids suggest that this may represent an immune-related [dermatologic adverse event (AE)]. Given that that immune-related [dermatologic] AEs take longer to develop, patients receiving pembrolizumab will need to be monitored more closely.” – by Bruce Thiel

Disclosure: The researchers report no relevant financial disclosures.