Corinne Armari‐Alla

PURPOSE: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with a broad spectrum of clinical manifestations and outcomes in children. The somatic BRAF(V600E) mutation occurs frequently, but clinical significance remains to be determined. PATIENTS AND METHODS: BRAF(V600E) mutation was investigated in a French LCH cohort. We analyzed associations between mutation status and clinical presentation, extent of disease, reactivation rate, response to therapy, and long-term permanent sequelae. RESULTS: Among 315 patients with successfully determined BRAF status, 173 (54.6%) carried a BRAF(V600E) mutation. Patients with BRAF(V600E) manifested more severe disease than did those with wild-type BRAF. Patients with BRAF(V600E) comprised 87.8% of patients (43 of 49) with multisystem LCH with risk organ involvement (liver, spleen, hematology), 68.6% of patients (35 of 51) with multisystem LCH without risk organ involvement, 43.9% of patients (86 of 196) with single-system LCH, and 42.1% of patients (8 of 19) with lung-involved LCH (P < .001). BRAF(V600E) mutation was also associated with organ involvement that could lead to permanent, irreversible damage, such as neurologic (75%) and pituitary (72.9%) injuries. Compared with patients with wild-type BRAF, patients with BRAF(V600E) more commonly displayed resistance to combined vinblastine and corticosteroid therapy (21.9% v 3.3%; P = .001), showed a higher reactivation rate (5-year reactivation rate, 42.8% v 28.1%; P = .006), and had more permanent, long-term consequences from disease or treatment (27.9% v 12.6%; P = .001). CONCLUSION: In children with LCH, BRAF(V600E) mutation was associated with high-risk features, permanent injury, and poor short-term response to chemotherapy. Further population-based studies should be undertaken to confirm our observations and to assess the impact of BRAF inhibitors for this subgroup of patients who may benefit from targeted therapy.

The French national cohort of children with Langerhans cell histiocytosis (LCH) has included 1478 patients since it was established in 1983. LCH therapeutic strategies substantially changed in 1998, so we have divided the cohort into two 15-year periods. Starting in 1998, therapy duration increased from 6 to 12 months, repeated induction therapy was performed in cases showing a poor response to the first induction with vinblastine and steroids, and refractory disease in a risk organ (RO+) was treated with cladribine and cytarabine. A total of 483 (33%) patients were enrolled before 1998, and 995 (67%) after 1998. Five-year survival was 96·6% (95% confidence interval: 95·4-97·5%) overall, improving from 92% pre-1998 to 99% post-1998 (P < 0·001 adjusted to disease extent). This change was supported by an increase in 5-year survival from 60% to 92% in the RO+ group. Survival was particularly associated with cladribine and cytarabine among refractory RO+ patients. Disease reactivation was slightly less frequent after 1998, due to better enrolment of single-system patients, extended therapy duration, and more efficient second-line therapy. The crude rates of endocrine and neurological sequelae (the most frequent sequelae) appeared to improve over time, but this difference was not observed when the analysis was stratified by disease extent.

Evans syndrome (ES) is a rare autoimmune disorder whose long-term outcome is not well known. In France, a collaborative pediatric network set up via the National Rare Disease Plan now provides comprehensive clinical data in children with this disease. Patients aged less than 18 years at the initial presentation of autoimmune cytopenia have been prospectively included into a national observational cohort since 2004. The definition of ES was restricted to the simultaneous or sequential association of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenic purpura (ITP). Cases were deemed secondary if associated with a primitive immunodeficiency or systemic lupus erythematosus. In December 2014, we analyzed the data pertaining to 156 children from 26 centers with ES whose diagnosis was made between 1981 and 2014. Median age (range) at the onset of cytopenia was 5.4 years (0.2-17.2). In 85 sequential cases, the time lapse between the first episodes of AIHA and ITP was 2.4 years (0.1-16.3). The follow-up period as from ES diagnosis was 6.5 years (0.1-28.8). ES was secondary, revealing another underlying disease, in 10% of cases; various associated immune manifestations (mainly lymphoproliferation, other autoimmune diseases, and hypogammaglobulinemia) were observed in 60% of cases; and ES remained primary in 30% of cases. Five-year ITP and AIHA relapse-free survival were 25 and 61%, respectively. Overall, 69% of children required one or more second-line immune treatments, and 15 patients (10%) died at the age of 14.3 years (1.7-28.1). To our knowledge, this is the first consistent long-term clinical description of this rare syndrome. It underscores the high rate of associated immune manifestations and the burden of long-term complications and treatment toxicity. Future challenges include (1) the identification of the underlying genetic defects inducing immune dysregulation and (2) the need to better characterize patient subgroups and second-line treatment strategies.

The safety and efficacy of rituximab have been retrospectively assessed in 17 children with Evans syndrome. Patients received 4 or 3 weekly doses of rituximab (375 mg/m(2) per dose) associated with prednisone, alone (14 patients) or associated with other immunosuppressive drugs. Complete or partial remission of at least one cytopenia was achieved in 13 out of the 17 patients (76%), and lasted in 11 of them with a mean follow-up of 2.4 years (range 0.5-7 years). Steroid therapy was stopped or tapered at 50-100% of the baseline dosage in all long-term responders. Moderate side effects and infection occurred only in 4 and 1 children respectively.