Abstract BACKGROUND Drugs that target the mitogen-activated protein kinase pathway can cause frequent and severe cutaneous toxicities with acneiform eruptions being one of the most common and challenging to manage. The literature is limited regarding treatment recommendations especially when this rash is refractory to first-line therapies. METHODS A single-institution case series regarding the treatment of acneiform eruptions with oral isotretinoin after failure of first-line therapies was performed. RESULTS Two female, adolescent patients who developed refractory acneiform eruptions while on trametinib were included. Their acneiform eruption emerged within the first cycle of trametinib requiring treatment with oral doxycycline plus a variety of topical medications. They remained on doxycycline for 6 and 7 months. Both patients then switched to oral isotretinoin after minimal rash response and rebound of the rash when attempting to discontinue doxycycline. The initial isotretinoin doses were 0.2-0.3 mg/kg/day rounded per pill size. Both patients required a dose reduction due to worsening xerosis. Once decreased, isotretinoin was well tolerated. No changes in baseline lipid panels or ALT were seen. No associated neurologic symptoms or pseudotumor cerebri. While on oral isotretinoin, no additional topical therapies were required to treat the acneiform eruption. The first patient’s acneiform rash improved from a CTCAE v5 grade 3 to grade 1 after only 3 weeks of isotretinoin. All locations of the rash responded to therapy. The second patient developed a grade 2 acneiform rash after starting trametinib and became ungradable with only residual pink papules to cheeks after receiving isotretinoin. CONCLUSIONS Both patients were successfully treated with isotretinoin after multiple prior therapies including 6 or more months of treatment with oral antibiotics. We recommend further research of treatment therapies in addition to oral antibiotics given concerns on their impact of the microbiome.

NURS-01. NOVEL TREATMENTS FOR ACNEIFORM ERUPTIONS CAUSED BY TARGETED THERAPIES IN THE PEDIATRIC POPULATION