A Phase 2 interventional study of Mirdametinib in Langerhans Cell Histiocytosis (LCH), Juvenile Xanthogranuloma (JXG) and Rosai-Dorfman Disease (RDD), sponsored by Children's Hospital Medical Center, Cincinnati. Recruiting at 1 site in United States. Open to participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-09-21.
Sponsored by Children's Hospital Medical Center, Cincinnati · Phase 2, Interventional, and Treatment
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.
Langerhans cell histiocytosis (LCH) is a rare blood disorder. Though affecting all ages, LCH occurs more often in children, with an increased incidence in children less than 1 year of age. The disease presents in various ways, with most children suffering bony lesions, and skin rashes. In some patients, LCH affects vital organs such as liver, spleen, bone marrow, and the central nervous system. This group of patients are at significant risk of serious illness and death and are thus said to have risk-organ-positive (RO+) LCH. Current treatments for LCH consist of chemotherapy combined with other medications. However, many patients, especially those with RO+ disease, do not respond to therapy. Of the patients that do respond, many suffer progression of disease after an initial response to therapy, or recurrence of disease after completion of therapy.
The purpose of this study is to see if treatment with mirdametinib in patients with LCH or other histiocytic disorders will be better than current treatments and with fewer side effects.
81 studies on the registry are indexed under Histiocytosis, Langerhans-Cell; 23 are open to participants now.
This study's planned enrollment of 40 is above the median of 24 across 64 interventional studies indexed under Histiocytosis, Langerhans-Cell.
Browse Histiocytosis, Langerhans-Cell studies →Children's Hospital Medical Center, Cincinnati is the lead sponsor of 673 studies on the registry; 130 are open to participants now.
Of its 57 completed or terminated interventional studies of FDA-regulated products, 31 (54%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subjects must be ≥ 2 years of age AND have a diagnosis of a histiocytic disorder that requires systemic therapy
Subjects must demonstrate adequate organ function as defined:
Exclusion Criteria:
Prior therapy with stipulations as described:
Risk factors for retinal vein occlusion (RVO) are listed. Exclusion should be considered by clinical discretion if they have any of the following risk factors for RVO at screening:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Mirdametinib will be dosed by mouth twice a day at a dose of 2 mg/m2 BID with a max of 4 mg BID (8 mg per day max).
Drug: Mirdametinib
Mirdametinib is administered by mouth twice daily on a continuous schedule, with each cycle being 4 weeks. Patients are instructed to take consecutive doses separated by a minimum of 6 hours and a maximum of 14 hours.
Response rate to mirdametinib
Best overall response rate to mirdametinib after 13 four-week cycles as defined by positron emission tomography (PET) or magnetic resonance imaging (MRI) (for isolated pituitary/central nervous system (CNS) disease) response criteria.
Time frame: 1 year (completion of 13 four week cycles)
Duration of response to mirdametinib
Duration of response to mirdametinib on study as defined by PET or MRI (for isolated pituitary/CNS disease) response criteria.
Time frame: 2 years (completion of 26 four week cycles)
Maximum Plasma Concentration (Cmax)
Blood samples will be drawn for the pharmacokinetic profile before, and during mirdametinib therapy. Maximum plasma concentration will be calculated as data allow.
Time frame: Day 1 of the first 5 four week cycles)
Time to peak drug concentration (Tmax)
Blood samples will be drawn for the pharmacokinetic profile before, and during mirdametinib therapy. Time to peak drug concentration (Tmax) will be calculated as data allow.
Time frame: Day 1 of the first 5 four week cycles)
Area under the plasma concentration time curve (AUC)
Blood samples will be drawn for the pharmacokinetic profile before, and during mirdametinib therapy. Area under the plasma concentration time curve (AUC) will be calculated as data allow.
Time frame: Day 1 of the first 5 four week cycles)
Started Feb 2024 (actual). Primary completion is estimated for Mar 2030, 73 months after the start.
Of 32 phase 2 interventional studies under Histiocytosis, Langerhans-Cell, half reached primary completion within 63 months of starting (the median), counting those still running; a quarter within 55 and three quarters within 85. This study's planned 73 months is above that.
How these figures are worked out, and which studies are left out of them.
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Studies of the drug tested here: Mirdametinib
Histiocytosis, Langerhans-Cell →
Children's Hospital Medical Center, Cincinnati →