OTHR-09. The prevalence and complex management of MEK inhibitor induced cutaneous side effects

BACKGROUND: Cutaneous side effects commonly occur with MEK inhibitor (MEKi) therapy and can be challenging to manage. METHODS: A retrospective chart review was performed on sixteen pediatric patients treated with MEKi therapy for at least three months. These patients were diagnosed with either a brain tumor, plexiform neurofibroma, Langerhans Cell Histiocytosis, or Parkes Weber Syndrome (PWS). OBJECTIVES: To describe cutaneous side effects from MEKi therapy, compare the side effect profiles of patients treated for different diagnoses, and compare the side effect profiles between different MEKi agents. RESULTS: The most prevalent cutaneous toxicities for all eligible patients were acneiform rash (81%, most common), paronychia (50%, second most common), hair changes and xerosis. Mean number of cutaneous skin toxicities were 3.2 (trametinib group: 3.4, selumetinib group: 2.8). Only one patient, treated with trametinib for PWS, did not experience a cutaneous side effect. The average number of interventions (new medication or over-the-counter product) recommended to prevent or treat cutaneous-related toxicities was 6.8 per person, the majority of those were for acne and paronychia. Over 75% of the interventions were topical. Of those who experienced an acneiform rash, the average number of recommended interventions were 3.1. Sixty two percent of these patients developed acne within the first cycle; average time to development was 2.6 months into therapy. Most exhibited improvement overtime following intervention. Those patients who experienced paronychia were treated with a mean of 3.1 interventions – 37.5% developed paronychia within the first cycle of therapy; average time to development was 3.9 months into therapy. CONCLUSIONS: Cutaneous side effects are common, occur early in therapy, and require multiple interventions. The number and complexity of these interventions may further complicate the overall management of cutaneous side effects given that the responsibility of the administration falls on the patient. This differs from traditional chemotherapy regimens.