Acneiform eruptions
In addition, the use of MAPK inhibitors can trigger acneiform eruptions. In one study, 77% of patients on trametinib developed acneiform eruption, but only 10% of those on trametinib in combination with dabrafenib developed acneiform eruption. “Inhibition of the MAPK pathway leads to decreased proliferative markers, further leading to decreased keratinocyte replication, increased inflammatory cytokine, apoptosis, thinning and abnormal epidermal differentiation, follicular rupture, and papule/pustule formation,” he said. For these cases, “treatment options are similar to what we use for regular acne except for here, use of systemic steroids is sometimes needed, especially in more severe cases. The reaction may be so severe as to lead to dose reduction or discontinuation of antineoplastic treatment.”
Effects on nail, hair
Paronychia and onycholysis are additional potential adverse events of MEK inhibitors and BRAF inhibitors alone or in combination, Dr. Itkin continued. Onycholysis is associated with dabrafenib alone or in combination with trametinib, while vemurafenib has been shown to induce acute paronychia and brittle nails. He said that secondary infections in these cases can be treated with the options familiar to dermatologists in their daily practice: oral doxycycline, azole antifungals, vinegar soaks, topical superpotent corticosteroids under occlusion, nail avulsion, and phenol nail matrix ablation.
Dr. Itkin noted that while PD-1 and PD-L1 inhibitors can cause hair repigmentation, CTLA-4 and PD-1 inhibitors are more likely to cause vitiligo. Appearance of vitiligo is regarded as a good prognostic factor in the treatment of melanoma with various checkpoint inhibitors alone or in combination with each other or with radiation therapy. “About 5% of melanoma patients treated with ipilimumab will develop vitiligo,” he said.
ICI-induced vitiligo differs from conventional vitiligo in that there is no family or personal history of autoimmunity; it presents as a flecked pattern of lesion on photo-exposed skin, and it lacks the Koebner phenomenon. In addition, induction of squamous neoplasms can occur with BRAF inhibitors, especially in patients with a high frequency of RAS mutations.
He said that coadministration of MEK inhibitors such as trametinib and cobimetinib may prevent induction of keratinocytic neoplasms.
Dr. Itkin reported having no relevant financial disclosures.