Langerhans Cell Histiocytosis (LCH) is a type of cancer that can damage tissue or cause lesions to form in one or more places in the body. Langerhans cell histiocytosis (LCH) is a cancer that begins in LCH cells (a type of dendritic cell which fights infection). Sometimes there are mutations (changes) in LCH cells as they form. These include mutations of the BRAF gene. These changes may make the LCH cells grow and multiply quickly. This causes LCH cells to build up in certain parts of the body, where they can damage tissue or form lesions.
For most patients with LCH, standard-of-care vinblastine/prednisone are used as front-line therapy while cytarabine therapy has been used as therapy for patients who develop recurrence. No alternate treatment strategy has been developed for frontline therapy in LCH.
The purpose of this research study is to compare previously used vinblastine/prednisone to single therapy with cytarabine for LCH. We will evaluate the utility of an imaging study called a positron emission tomography (PET) scan to more accurately assess areas of LCH involvement not otherwise seen in other imaging studies as well as response to therapy. We also want to identify if genetic and other biomarkers (special proteins in patient's blood and in patient's cancer) relate to the response of patients LCH to study treatment.
Patient must have biopsy-confirmed diagnosis of Langerhans cell histiocytosis.
Patient must be between 0-21 years of age.
Patient must have a Karnofsky performance score ≥ 50% or Lansky performance score ≥ 50%.
Central Nervous System (CNS) risk lesions/special site disease: patients with single bone sites that are CNS-risk (sphenoid, mastoid, orbital, zygomatic, ethmoid, maxillary, or temporal bones, the cranial fossa, pituitary gland or neurodegenerative disease) or are "special sites" (odontoid peg, vertebral lesion with intraspinal soft tissue extension) require systemic therapy as standard of care and thus are eligible for the study.
Functionally critical lesions: A single lesion not described above which may cause "functionally critical anatomic abnormality" wherein attempts at local therapy (such as surgical curettage or radiation) would cause unacceptable morbidity. These patients may be enrolled with written approval of the Coordinating Center PI or Vice-Chair and documentation of the rationale justifying systemic therapy.
Asynchronous multisite LCH presentation: A patient may also have any single site of disease involvement at the time of enrollment if they previously had at least one other site of LCH disease in the past (which may have been treated with local therapy/surgery as described), as long as no systemic therapy was previously given per protocol guidelines.
Patient may not have severe renal disease (creatinine greater than 3 times normal for age OR creatinine clearance < 50 ml/m2/1.73m²).
Parallel
Cytarabine
DrugCytarabine 100 mg/m\^2/day IV for five consecutive days. This five-day cycle will be repeated every 21 days for a total of four cycles for all patients regardless of response. Each new cycle may not begin until absolute neutrophil count (ANC) is ≥ 750/mcL and platelet count is ≥ 75,000/mcL.
Vinblastine/prednisone
DrugVinblastine/Prednisone +/- 6-mercaptopurine based on risk category. Patients with high-risk organ involvement (liver, spleen, hematopoeitic system) will receive 6-mercaptopurine during Continuation Therapy as this is the current standard of care treatment. Vinblastine 6 mg/m\^2/dose IV push weekly for patients ≥ 12 months of age. Vinblastine will be dosed at 3 mg/m\^2/dose for patients under 6 months of age, and dosed at 4.5 mg/m\^2/dose for patients 6 months of age to 11.99 months of age. Prednisone (or prednisolone) 20 mg/m2/dose by mouth twice a day
Time to determine 1-year event-free survival (EFS) of patients treated with cytarabine monotherapy for LCH, compared directly with that of standard-of-care vinblastine/prednisone (Events include progression of LCH, relapse, or death).
A Kaplan-Meier curve will be used to compare event-free survival between treatment groups. Curves will be compared using the log-rank statistic. Patients will be followed for up to 5 years after one year of therapy. Patients who have not had the event by the 5-year mark will be censored observations. Patients who are lost to follow-up without having an event will be censored at the time of last contact. Statistical significance will be assessed at the 0.05 level. A Cox proportional hazards model will also be used to estimate the Hazards Rate for combined events in the Cytarabine group versus standard therapy. A multiple regression model will also be used to estimate the adjusted HRs for genotype and baseline risk of death (high vs. low).
Durable responses with 2-year and 5-year EFS and OS of the patients treated with cytarabine versus vinblastine/prednisone for LCH.
Overall disease response at each timepoint will be assigned based on the lesion or organ system with worst response. For disease response not defined by the criteria included in the protocol, guidelines established in the RECIST criteria will be used.
Number of toxicities (including psychosis, hypertension, neuropathy, fever, headache) in the patients treated with cytarabine versus vinblastine/prednisone for LCH.
Toxicity will be graded by the NCI Common Toxicity Criteria Version 5.0.
Rate at which patients achieve non-active disease on cytarabine versus vinblastine/prednisone therapy.
RECIST criteria will be used for assessing disease response
Time to eradication of BRAF-V600E cells or other LCH-defining mutation
This will be quantified by quantitative real-time PCR.
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