The purpose of this study is to see if treatment with mirdametinib in patients with Langerhans cell histiocytosis (LCH) or other histiocytic disorders will be better than current treatments and with fewer side effects.
Subjects must be ≥ 2 years of age AND have a diagnosis of a histiocytic disorder that requires systemic therapy
If patient has had a diagnostic biopsy, biopsy must be reviewed and confirmed by CCHMC pathologist as feasible
If patient has had a biopsy but has not had molecular testing done, must have tissue available for mutational analysis
If patient has isolated pituitary/CNS disease or situations where biopsy is not feasible, positive ddPCR blood test for mutation associated with histiocytic neoplasm with clinical features of histiocytosis is sufficient
Myelosuppressive Chemotherapy: Must not have received any cytotoxic chemotherapy which impacts the growth and development of cells in the bone marrow within 14 days of enrollment onto this study (i.e. cytarabine, cladribine, clofarabine, mercaptopurine, methotrexate, vinblastine)
MEK Inhibitors: Must not have received a MEK inhibitor within 30 days (or 5 half-lives, whichever is longer) of enrollment, NOR have had disease progression on MEK inhibitor
Steroids: Due to the increased risk of an ocular event, the use of systemic oral, inhaled, or ocular glucocorticoid therapy is prohibited within 14 days prior to first dose of mirdametinib. Throughout the treatment period, short term glucocorticoid treatment (30 days or less) is permitted. Any patients requiring long-term steroid use (more than 30 consecutive days) are not eligible. The exception to this rule is subjects with endocrine deficiencies who require physiologic steroids
Radiation: Must not have received radiation within 14 days of study enrollment or have received radiation to the orbit at any time