Clinical Research Directory

Inherited Genetic Susceptibility in Langerhans Cell Histiocytosis (LCH)

The long-term goal is to define the mechanisms of pathogenesis underlying Langerhans cell histiocytosis (LCH). The overall objectives of the current study are to characterize the role of SMAD6 inherited genetic variation on LCH susceptibility and identify germline genomic regions associated with LCH somatic mutations. Building from preliminary data, the central hypotheses are: (1) causal genetic variants in SMAD6 underlie susceptibility to LCH, and (2) differences in LCH-related somatic activating mutations by race/ethnicity are related to Amerindian (i.e., Native American) genetic ancestry. The Central hypothesis will be tested by pursuing the specific aims.

Adebrelimab Combined With Trametinib in the Treatment of Refractory Recurrent Langerhans Cell Histiocytosis in Children and Adolescents

Phase 1, 1 case in total Subject 1: This study marks the first application of Adebrelimab in pediatric patients with Langerhans Cell Histiocytosis (LCH). The initial dose is 20 mg/kg, delivered via a 60-minute intravenous infusion. If no Dose-Limiting Toxicity (DLT) occurs, the second dose of 20 mg/kg will be administered in the second cycle. Treatment cycles consist of dosing every 4 weeks, up to a maximum of 6 cycles. Phase 2, 2-5 cases in total Subjects 2 and 3: If the first subject exhibits no DLT, the second and third subjects will be enrolled and receive 20 mg/kg of Adebrelimab on day 1. Treatment cycles will last 4 weeks, with dosing administered every 4 weeks, for up to 6 cycles. Subjects 4-6: If one DLT occurs among the first three subjects, three additional subjects will be enrolled and given 20 mg/kg of Adebrelimab. If two or more DLTs occur among the first three subjects, three additional subjects will be enrolled and administered a reduced dose of 10 mg/kg. Following the successful completion of these phases, a subsequent phase will commence to further assess the efficacy and safety of Adebrelimab and fulfill the biological research objectives.

Biomarkers for Diagnostic, Prognostic and of Response to Treatment in Adult Langerhans Cell Histiocytosis

Adult Langerhans histiocytosis (LCH) is a rare disease of unknown etiology, characterized by the activation of the MAPK (Mitogen-activated protein kinases) pathway, driven by various somatic mutations in the specific lesions of involved organs/tissues. LCH is currently classified as myeloid neoplasia with an inflammatory component. In patients with active systemic LCH, MAPK mutations may also be identified in plasma free cell DNA in patients. In contrast, circulating MAPK mutations seem more rarely detected in patients with LCH limited to a single organ/tissue (single system disease), but this has not been accurately assessed in a large series of patients. The clinical presentation of LCH is very diverse, the prognosis variable, and the evolution marked by the occurrence of flares of the disease. A definitive diagnosis of LCH warrants histological confirmation obtained by a biopsy of an involved organ. In case of Pulmonary Langerhans cell histiocytosis (PLCH), a presumptive diagnosis is often acceptable when lung-computed tomography (CT) shows a nodulo-cystic pattern after excluding alternative diagnoses. In contrast, in case of purely cystic lung CT pattern, PLCH may be difficult to differentiate from other diffuse cystic lung diseases (mainly lymphangioléiomyomatose (LAM) and BHD (Birt-Hogg-Dubé syndrom), and eventually other rare disorders). Advanced PLCH may even be misdiagnosed as pulmonary emphysema that also occurs in smokers. In these situations, confirmation of PLCH warrants lung tissue, obtained most often by surgical lung biopsy that comprises significant morbidity or is not feasible in patients with altered lung function. Thus, the identification of specific blood biomarkers of cystic PLCH would be very useful. On another hand, personalized management of adult patients with LCH is limited given the absence of predictive factors for prognosis or response to treatment. The aim of this prospective study is to describe precisely the clinical phenotype at diagnosis and during follow-up of a large cohort of adult LCH patients and to seek for blood biomarkers eventually associated with prognosis or response to specific treatment. For patients with cystic PLCH specific markers for non-invasive diagnosis will also be investigated. In the subgroup of patients with Single system (SS) LCH and specific driver MAPK mutation in tissue lesions, we will also look for the identification of this mutation in plasma free DNA at the time of a flare of the disease.

Adult Pulmonary Langerhans Cell Histiocytosis: a National Registry-based Prospective Cohort Study

The long-term outcomes of adult patients with pulmonary Langerhans cell histiocytosis (PLCH), particularly survival, is largely unknown. This is the first prospective study in the field evaluating the long-term outcomes of PLCH patients. This french countrywide registry-based study included a large cohort of PLCH patients followed for a sufficiently long period to address risk factors of long-term outcomes of PLCH patients.