Multi-centre pilot study of 2-chlorodeoxyadenosine and cytosine arabinoside combined chemotherapy in refractory Langerhans cell histiocytosis with haematological dysfunction

Langerhans cell histiocytosis of thyroid and bilateral parotid diagnosed on fine needle aspiration cytology

LCH has a distinct site predilection and cytological feature. However, it can cause diagnostic difficulties at unusual sites or deviated cytomorphology. FNAC is a minimally invasive procedure that can be performed in any organ (parotid and thyroid where biopsy is not commonly indicated) and multiple sites/organs simultaneously for diagnosis. FNA sampling can also help with cell block preparation for performing immunohistochemistry and molecular studies if necessary.

High risk Langerhans cell histiocytosis in children: the role of salvage in improving the outcome. A single center experience

BACKGROUND

In pediatric multi-system high risk organs (RO +) Langerhans cell histiocytosis (LCH), failing 1st line treatment has the highest mortality. We aim to present the outcome of failure of 1st line whether due to disease progression (DP) at end of induction or reactivation (REA) after initial better status response.

PATIENTS AND METHODS

Sixty-seven RO + LCH patients with hemopoietic, hepatic or splenic involvement, treated between 2007 and 2019 were retrospectively analyzed. The median follow-up (IQR) is 6 years (4-8.8 y).They were subjected to 2 eras of treatment; one with salvage by 2-Cda based regimen (2-CdABR) and another without.

RESULTS

Of 67 patients, M/F 40/27, median age 1.74 y (0.2-10 y), 42 failed 1st line (62.7%). Of them DP n = 22 (52%) and REA n = 20 (48%). Of those with DP, 9/22 patients received 2-CdABR, where 5 survived in better status. While the remaining 13 did not receive 2-CdABR and all of them died. Otherwise, of those with REA, 12/20 reactivated on RO + mode. Of them, 8/12 received 2-CdABR, where only one survived in better status and the remaining 4 received vinblastine-based regimen,where 2 died and 2 were rescued. RO + 5-year overall survival (OS) was 65% (CI 95% 54 -78) while the event free survival (EFS) 36% (26.3-50.1). The OS of DP 27% (14-54) versus REA 67% (49-93) p 0.004. OS of DP with 2-CdABR 56% (31-97.7) versus 8% without (2-51), p < 0.001. While OS of REA with 2-CdABR 38% (13-100) versus 74% without (53-100) p 0.7.

CONCLUSION

Survival of RO + remains limited. Failure of 1st line in RO + due to DP carries worse prognosis in relation to REA. In DP those who were not salvaged by 2-CdABR, showed dismal outcome. This could not be shown when applied in REA.

[Therapeutic Strategies In Children And Adolescents With Langerhans Cell Histiocytosis]

The current standard therapy for children and adolescents with newly diagnosed Langerhans cell histiocytosis (LCH) is based on the two drugs prednisone and vinblastine. In patients with insufficient treatment response or disease relapse, the choice of second-line treatment depends on risk organ involvement (liver, spleen, and hematopoietic system). This article will give an overview of current data concerning therapeutic options in the different settings of children and adolescents with LCH. Due to limited evidence, these strategies have not been described in detail in the updated guidelines on pediatric LCH. In addition, the use of targeted therapy such as MAP-kinase inhibitors will be discussed. The reference center for LCH should be contacted if therapeutic options beyond the standard regimen are considered for treatment. All children and adolescents with LCH should be enrolled in registries or prospective studies.

Cladribine and cytarabine in children refractory high risk multisystem Langerhans cell histiocytosis

There is no uniform regimen for refractory Langerhans cell histiocytosis (LCH). We retrospectively described patients with refractory multisystem and risk organ involvement LCH treated with the low-dose (Ara-c, 100 mg/m2/d × 5day; 2-CDA, 5 mg/m2/d × 5day) chemotherapy (LDC) and the intermediate-dose (Ara-c, 500 mg/m2/d × 5day; 2-CDA, 9 mg/m2/d × 5day) chemotherapy (IDC). 26 patients and 10 patients receiving the LDC and IDC regimen from January 2013 to December 2016 were included in the study. The overall response rate exhibited no significant difference between the LDC and IDC groups after four courses (76.9% vs 90%, P = 0.375) and eight courses (80.8% vs 100%, P = 0.135) of treatment. No statistical differences in the overall survival rate were observed between the two groups, but 5-year event-free survival rate of patients in the IDC group was higher than that in the LDC group at the median follow-up of 6.16 and 5.07 years (88.9% vs 52.9%, P = 0.033). The patients in the IDC group had more severe myelosuppression than those in the LDC group (grade 3/4 myelosuppression, 80% vs 19.2%, P = 0.001). The intermediate-dose regimen of 2CDA and Ara-c had a higher event-free survival rate and a similar overall survival rate compared with the low-dose regimen.

Children's Oncology Group's 2023 blueprint for research: Non-Hodgkin lymphoma

Pediatric non-Hodgkin lymphoma (NHL) includes over 30 histologies (many with subtypes), with approximately 800 cases per year in the United States. Improvements in survival in NHL over the past 5 decades align with the overall success of the cooperative trial model with dramatic improvements in outcomes. As an example, survival for advanced Burkitt lymphoma is now >95%. Major remaining challenges include survival for relapsed and refractory disease and long-term morbidity in NHL survivors. Langerhans cell histiocytosis (LCH) was added to the NHL Committee portfolio in recognition of LCH as a neoplastic disorder and the tremendous unmet need for improved outcomes. The goal of the Children' Oncology Group NHL Committee is to identify optimal cures for every child and young adult with NHL (and LCH). Further advances will require creative solutions, including engineering study groups to combine rare populations, biology-based eligibility, alternative endpoints, facilitating international collaborations, and coordinated correlative biology.

Phase 2 study of oral thalidomide-cyclophosphamide-dexamethasone for recurrent/refractory adult Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a clonal histiocytic neoplasm with various clinical manifestations and heterogeneous prognoses. No standard therapy is available for recurrent/refractory LCH patients. This single-center, single-arm, phase 2 study enrolled 32 patients diagnosed with recurrent/refractory LCH. The TCD regimen (thalidomide 100 mg daily, cyclophosphamide 300 mg/m² Day 1, 8, 15, and dexamethasone 40 mg Day 1, 8, 15, 22 every 4 weeks) was administered for 12 cycles and thalidomide alone as maintenance for 12 months. The primary endpoint was event-free survival (EFS). Events were defined as progression during or after TCD therapy or death from any cause. After a median follow-up of 22 months (range 5-24 months), no patient died of all causes. The overall response rate was 87.5%, including 18 patients (56.3%) achieving complete remission and 10 patients (31.3%) as partial remission. The estimated 24-month EFS was 64.0%. Patients with risk organ involvement had similar EFS compared to patients without risk organ involvement (P = 0.38). The common toxicities of TCD regimen include grade 1-2 neutropenia (18.8%), grade 1-2 constipation (12.5%), grade 1-2 tiredness (9.4%) and grade 2 peripheral neuropathy (12.5%). Oral thalidomide, cyclophosphamide and dexamethasone are effective and safe regimen for recurrent/refractory LCH patients, particularly for patients with risk organ involvement.

Neutralizing Anti-IL-17A Antibody Demonstrates Preclinical Activity Enhanced by Vinblastine in Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm characterised by the accumulation into granulomas of apoptosis-resistant pathological dendritic cells (LCH-DCs). LCH outcome ranges from self-resolving to fatal. Having previously shown that, (i) monocyte-derived DCs (Mo-DCs) from LCH patients differentiate into abnormal and pro-inflammatory IL-17A-producing DCs, and (ii) recombinant IL-17A induces survival and chemoresistance of healthy Mo-DCs, we investigated the link between IL-17A and resistance to apoptosis of LCH-DCs. In LCH granulomas, we uncovered the strong expression of BCL2A1 (alias BFL1), an anti-apoptotic BCL2 family member. In vitro, intracellular IL-17A expression was correlated with BCL2A1 expression and survival of Mo-DCs from LCH patients. Based on the chemotherapeutic drugs routinely used as first or second line LCH therapy, we treated these cells with vinblastine, or cytarabine and cladribine. Our preclinical results indicate that high doses of these drugs decreased the expression of Mcl-1, the main anti-apoptotic BCL2 family member for myeloid cells, and killed Mo-DCs from LCH patients ex vivo, without affecting BCL2A1 expression. Conversely, neutralizing anti-IL-17A antibodies decreased BCL2A1 expression, the downregulation of which lowered the survival rate of Mo-DCs from LCH patients. Interestingly, the in vitro combination of low-dose vinblastine with neutralizing anti-IL-17A antibodies killed Mo-DCs from LCH patients. In conclusion, we show that BCL2A1 expression induced by IL-17A links the inflammatory environment to the unusual pro-survival gene activation in LCH-DCs. Finally, these preclinical data support that targeting both Mcl-1 and BCL2A1 with low-dose vinblastine and anti-IL-17A biotherapy may represent a synergistic combination for managing recurrent or severe forms of LCH.

Second-line regimen for CNS-involved pediatric Langerhans cell histiocytosis

PURPOSE

Langerhans cell histiocytosis (LCH) can affect any organ. Central nervous system (CNS) involvement is rare, and its management is poorly understood. This study aimed to analyze the clinical response and prognosis of pediatric LCH with central diabetes insipidus (CDI) treated with second-line therapy with cytarabine (Ara-c), cladribine (2-cdA), dexamethasone, and vindesine.

METHODS

This retrospective case series study included pediatric LCH with CDI treated at Beijing Children's Hospital affiliated with Capital Medical University (11/2012-01/2018). After the first-line 2009-LCH regimen, patients with active disease/worse response, relapse, or no significant improvement in risk organs, pituitary, or lung were given the second-line therapy. Baseline characteristics, clinical response and adverse reactions were observed.

RESULTS

Twenty-six children with CDI and disappearance of hyperintensity in the posterior pituitary were included. They received "Regimen A" Ara-c + dexamethasone + vindesine (n = 7) or "Regimen B" Ara-c + dexamethasone + vindesine + 2-cdA (n = 19) as second-line therapy. There were 14 patients with CDI but without pituitary stalk thickening (PST) and 12 with CDI and PST. In patients with CDI alone, 4/4 patients receiving Regimen A and 3/10 receiving Regimen B improved. All patients with CDI and PST showed improvement for PST. The reappearance of hyperintensity at the posterior pituitary was observed in 10 patients with CDI. All 26 children were alive after a median follow-up of 40.5 months. There were no chemotherapy-related deaths.

CONCLUSION

A combined therapy with Ara-c, 2-cdA, dexamethasone, and vindesine could partially alleviate pituitary disease conditions in pediatric LCH with CNS involvement, with good tolerance.

Clinical and prognostic characteristics of 95 cases of Langerhans cell histiocytosis in children: a single-institute experience from 2013 to 2020

BACKGROUND

This study aimed to understand the clinical characteristics and outcomes of children with Langerhans cell histiocytosis (LCH) in China.

METHODS

We conducted a retrospective study of 95 paediatric patients with LCH in West China Second University Hospital of Sichuan University between July 2013 and August 2020.

RESULTS

The onset age of multisystem LCH (MS-LCH) patients with risk organ (RO) involvement was younger than that of MS-LCH without RO involvement (p = .002) and single system LCH (p < .001) patients; bone was the most frequently involved organ, followed by the skin. Of all, the BRAF-V600E mutation was detected in 48 out of 84 patients who underwent gene analysis. Additionally, in our study, BRAF p.N486_T491 > K, BRAF p.L485_P490delinsF, BRAF p.R506_K507insLLR, ARAF p.Q349_F351delinsL and MAP2K1 p.Q58_E62del were known mutations in the mitogen-activated protein kinase (MAPK) pathway. The BRAF-V600E genotype in the tissue and plasma prior to therapy were detected in 16 patients, and the concordance was only 37.5% (6/16). According to the modified LCH-III-based-protocol, JLSG-02 protocol chemotherapy, and vemurafenib, the estimated five-year overall survival, event-free survival (EFS) and cumulative reactivation rates of 95 patients were 98.8%, 74.6% and 24.5%, respectively. The EFS rate in good responders was better than that in poor responders at 12-week (HR = 0.022, 95%CI 0.002-0.231, p = .002), and EFS was not affected by age, RO involvement or BRAF-V600E mutation. Regarding sequelae, nine patients had central diabetes insipidus and two had growth retardation.

CONCLUSIONS

In this study, LCH was a highly heterogeneous disease characterized molecularly by MAPK-pathway activating mutations. Vincristine, prednisone and cytarabine-based chemotherapy combined with vemurafenib improved the prognosis of childhood LCH. In future, prospective clinical trials and novel therapeutic strategies should be developed to improve outcomes in paediatric patients with LCH.KEY MESSAGEChildren with Langerhans cell histiocytosis in China present highly heterogeneous clinical characteristics, with up to 60% of cases harbouring mutations in MAPK pathway.Treatment response at 12-week is associated with EFS in our study.Vincristine, prednisone and cytarabine-based chemotherapy combined with vemurafenib improved the prognosis of Chinese childhood LCH, but the reactivation rate is still high.

Clofarabine monotherapy in two patients with refractory Langerhans cell histiocytosis

Background

Better therapeutic options other than conventional chemotherapy for pediatric patients with refractory Langerhans cell histiocytosis (LCH) remain undetermined.

Case

We successfully treated two patients with refractory and risk organ negative LCH with clofarabine (CLO) monotherapy after recurrence. We administered total 23 courses of CLO monotherapy in patient 1 and 4 courses in patient 2. Both patients had distinct clinical manifestations but achieved a durable complete response with acceptable adverse effects of transient myelosuppression. CLO monotherapy was still effective when he had the second recurrent lesion after first completion of CLO in patient 1. We could discontinue prednisolone to control his refractory inflammation of LCH after completing CLO chemotherapy in patient 2.

Conclusion

Although large‐scale studies are warranted, CLO monotherapy could be a therapeutic option for high efficacy and feasibility besides other intensive combination chemotherapies or allogeneic hematopoietic stem cell transplantation for refractory LCH without risk organ involvement in children.

Clinical characteristics and outcomes of Langerhans cell histiocytosis at a single institution in Thailand: a 20-year retrospective study

Background

Langerhans cell histiocytosis (LCH) is a rare disease characterized by the various systems involved and clinical manifestations with a wide range of symptoms.

Objectives

To describe clinical characteristics, imaging, treatment, and outcomes of pediatric LCH at Phramongkutklao Hospital, Bangkok, Thailand.

Methods

We conducted a 20-year retrospective review of the medical records of patients diagnosed with LCH from birth to 21 years old from January 1, 1997, to December 31, 2016.

Results

In all, 14 patients with median age of 2.5 years were studied. Six (43%) patients had single-system (SS) LCH. Five patients (63%) with multisystem (MS) LCH (n = 8. 57%) had risk-organ involvement (RO+). All patients had plain X-ray imaging of their skull with 11 (79%) showing abnormal findings. Tc-99m bone imaging and fluorodeoxyglucose F18 (FDG) positron emission tomography (PET)-computed tomography (CT) demonstrated abnormal findings in 8 (89%) and 4 (29%) patients, respectively. The 5-year event-free survival (EFS) for patients with RO+ MS-LCH was less than that for those without risk-organ involvement (RO-) MS-LCH and SS-LCH (20% vs. 100%, P = 0.005). Hematological dysfunction, hypoalbuminemia, and conjugated hyperbilirubinemia may be worse prognostic factors for RO+ MS-LCH.

Conclusion

FDG-PET-CT might have a greater accuracy to detect LCH disease than conventional plain X-ray and Tc-99m bone imaging. RO+ MS-LCH has been encountered with relapse and poor outcomes. Hematopoietic involvement, hypoalbuminemia, and conjugated hyperbilirubinemia may be worse prognostic factors for RO+ MS-LCH.

Egyptian experience in Langerhans cells histiocytosis: frequent multisystem affection and reactivation rates

Background: Histiocytoses are unique disorders; their clinical presentations vary from self-healing lesions to life-threatening disseminated disease. Objectives: We aimed to evaluate the different clinical presentations, frequency of reactivations, and treatment outcome of Langerhans cell histiocytosis among Egyptian children. Methods: we restrospectively analyzed the data of 37 Langerhans cell histiocytosis patients (LCH) registered at Ain Shams University Children's Hospital for clinicopathological features, treatment modalities and their outcomes. Results: Twenty seven (73%) of the studied patients with LCH had multisystem disease (MS), 24 (88.9%) of them had risk organ involvement (MS RO+) and only 3 without risk organ (MS RO-). Most of the patients received LCH III protocols. Eleven patients (29.7%) had reactivations with median time till reactivation of 17 months (IQR 5-23).Reactivation rates were 40% and 50% in patients with no evidence of active disease (NAD) and those with active disease better (AD better) at week 6 evaluation respectively (p = 0.71).We report 9 deaths (all had MS RO+, two died after reactivation and 7 had progressive disease. The 5 years EFS and OS were 49.4% and 81.2% respectively. Risk stratification did not significantly affect the EFS or OS (p = 0.64 and p = 0.5 respectively). Conclusion: A high reactivation rate was encountered in children with LCH and MS-RO + irrespective of 6 weeks response to induction therapy. A high mortality in patients with progressive disease necessitates a possible earlier aggressive salvage in such group.

Multisystem involvement Langerhans cell histiocytosis in an adult: A case report

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare condition wherein Langerhans cells proliferate abnormally, adversely impacting organs including lymph nodes, bones, skin, lungs, and pituitary gland. The LCH disease course varies widely among patients from a self-limiting condition to one that progresses rapidly and culminates in death. It is uncommon for multisystem LCH to be observed in adults. Herein we describe a woman suffering from multi-system LCH involvement.

CASE SUMMARY

A 37-year old Chinese woman was admitted to the hospital in June 2019 suffering from dyspnea that had progressed over the course of 5 years. Her medical history included: central diabetes insipidus (DI) that had been treated via radiotherapy, desmopressin acetate, and bromocriptine; bilateral pneumothorax with two surgeries having been performed to remove bullae; and autoimmune hepatitis that had been unsuccessfully treated using a combination of methylprednisolone and mycophenolate mofetil. A chest computed tomography (CT) scan revealed the presence of multiple pulmonary cysts of varying sizes. We re-analyzed right pulmonary bullae samples that had been removed in 2014, performed a systematic ¹⁸F-FDG PET/CT analysis, and convened a multidisciplinary medical team to diagnose and treat this patient. As a result, we were able to eventually diagnose this patient with LCH that was not associated with BRAF-V600E mutations.

CONCLUSION

We hope to emphasize the importance of systemic evaluation and of cooperation between multidisciplinary physicians with the goal of improving awareness and detection of this orphan disease.

Long-term efficacy and safety of 2CdA (cladribine) in extra-pulmonary adult-onset Langerhans cell histiocytosis: analysis of 23 cases from the French Histiocytosis Group and systematic literature review

Langerhans cell histiocytosis (LCH) is a rare protean disease that usually affects children. Few data are available for management of adult-onset cases. A complete picture of the efficacy and safety of 2CdA (2-chlorodeoxyadenosine, cladribine) is lacking. We report a retrospective multicentre study of 23 adult LCH (a-LCH) patients who received single-agent 2CdA and a systematic literature review. All had previously received systemic therapy (vinblastine, n = 19). Response to 2CdA was evaluable in 22 cases. Overall response rate (ORR) was 91%. Complete response (CR) occurred in 11 cases (50%). Nine patients (39%) developed grade 3-4 neutropenia and/or severe infection. A literature review yielded 48 additional cases. A pooled analysis confirmed our findings (ORR: 88%, CR: 49%). CRs were rare with cumulative dose <50 mg/m² . Disease progression rates were 20% and 30% at two and five years, respectively. Partial response (PR) to 2CdA was predictive of disease progression. Among eight re-treated patients, five went into CR, two in PR, and one died. Single-agent 2CdA is effective in reactivated a-LCH, including at intermediate doses. Toxicity, significant but acceptable, warrants infectious prophylaxis. Complete responders may enter prolonged remission. Further studies are needed to determine 2CdA sequencing with other agents (vinblastine, cytarabine).

Merkel cell polyomavirus and Langerhans cell neoplasm

BACKGROUND

The relationship between various external agents such as pollen, food, and infectious agents and human sensitivity exists and is variable depending upon individual's health conditions. For example, we believe that the pathogenetic potential of the Merkel cell polyomavirus (MCPyV), the resident virus in skin, is variable and depends from the degree of individual's reactivity. MCPyV as well as Epstein-Barr virus, which are normally connected with humans under the form of subclinical infection, are thought to be involved at various degrees in several neoplastic and inflammatory diseases. In this review, we cover two types of Langerhans cell neoplasms, the Langerhans cell sarcoma (LCS) and Langerhans cell histiocytosis (LCH), represented as either neoplastic or inflammatory diseases caused by MCPyV.

METHODS

We meta-analyzed both our previous analyses, composed of quantitative PCR for MCPyV-DNA, proteomics, immunohistochemistry which construct IL-17 endocrine model and interleukin-1 (IL-1) activation loop model, and other groups' data.

RESULTS

We have shown that there were subgroups associated with the MCPyV as a causal agent in these two different neoplasms. Comparatively, LCS, distinct from the LCH, is a neoplastic lesion (or sarcoma) without presence of inflammatory granuloma frequently observed in the elderly. LCH is a proliferative disease of Langerhans-like abnormal cells which carry mutations of genes involved in the RAS/MAPK signaling pathway. We found that MCPyV may be involved in the development of LCH.

CONCLUSION

We hypothesized that a subgroup of LCS developed according the same mechanism involved in Merkel cell carcinoma pathogenesis. We proposed LCH developed from an inflammatory process that was sustained due to gene mutations. We hypothesized that MCPyV infection triggered an IL-1 activation loop that lies beneath the pathogenesis of LCH and propose a new triple-factor model.

[Clinical features and prognosis of Langerhans cell histiocytosis in children: an analysis of 34 cases]

OBJECTIVE

To investigate the clinical features and prognosis of children with Langerhans cell histiocytosis (LCH).

METHODS

A retrospective analysis was performed for the clinical data of 34 children with newly diagnosed LCH.

RESULTS

The 34 children had a median age of 14.5 months (range: 22 d to 60 months). Of all 34 children, 23 were aged 0-2 years and 11 were aged >2 years. There were 17 children in the high-risk group and 17 in the low-risk group. Thirty children received chemotherapy, and the 6-week and 12-month overall response rates were 67% (20/30) and 87% (26/30), respectively. The 3-year overall survival (OS) rate was 86%±6% and the 3-year event-free survival (EFS) rate was 64%±9%. Compared with the low-risk group, the high-risk group had significantly lower 6-week chemotherapy response rate (47% vs 87%; P<0.05), 3-year OS rate (72%±12% vs 100%; P<0.05), and 3-year EFS rate (46%±13% vs 82%±9%; P<0.05). There was no significant difference in the 12-month chemotherapy response rate between the high-risk and low-risk groups (80% vs 93; P>0.05). The high-risk group had a recurrence rate of 27% and a mortality rate of 27%. There were no recurrence or deaths in the low-risk group.

CONCLUSIONS

Children with LCH have a high overall survival rate, but the high-risk patient has a low 6-week response rate of induction chemotherapy and poor long-term prognosis.

Insights into the pathogenesis of Langerhans cell histiocytosis: the development of targeted therapies

More than a century after its first description, Langerhans cell histiocytosis (LCH) still remains an intriguing disease. Considerable progress in understanding its biology has been achieved recently. Description of the V600E BRAF mutation in samples of LCH tissue in 2010 was followed by description of additional mutations, all leading to constitutive ERK activation. Current experimental data suggest that LCH is a myeloid neoplasia with inflammatory properties, yet the exact pathophysiology remains poorly understood. Disease management paradigms have changed over time, closely reflecting the evolving view of the nature of the disease. The international Histiocyte Society have conducted three prospective clinical studies on multisystem LCH since the early 1990s. The standard frontline therapy for patients with multisystem LCH based on the cumulative knowledge of those trials consists of 6–12 weeks of initial therapy (daily oral steroids and weekly vinblastine injections), followed by pulses of prednisolone/vinblastine every 3 weeks, for a total treatment duration of 12 months. A currently ongoing study (LCH-IV) with a complex design (five interventional and two observational strata) targets further reduction of mortality and morbidity by tailoring treatment intensity depending on expected risk, as well as by exploring treatment regimens for special locations. Current knowledge on LCH pathobiology opens opportunities for improvement in the patient outcome. The activating BRAF and MAP2K1 mutations collectively accounting for about 75% of the LCH population as well as the resulting constitutive activation of downstream ERK offer an opportunity for targeted treatment. Related issues (eg, finding most effective and less toxic drugs or combinations, appropriate dosage, and optimal treatment duration) must be addressed in controlled prospective trials. Additional mechanisms, such as the interactions of the mutated dendritic cell clone with other inflammatory cells and key cytokines and chemokines, still remain attractive targets for therapeutic intervention, particularly in patients with localized, less aggressive disease.

Langerhans Cell Histiocytosis: A Clinicopathologic Review and Molecular Pathogenetic Update

Langerhans cell histiocytosis (LCH) comprises a wide spectrum of clinical disorders that have in common a proliferation of Langerhans-type cells with characteristic morphologic, immunophenotypic, and ultrastructural features. In part because of the diverse clinical manifestations of LCH, there has long been controversy over whether LCH is best considered a reactive process or a neoplasm. Herein, we discuss the clinical and pathologic features of LCH, including recent advances in the understanding of the molecular pathogenesis of this disease that support its categorization as a neoplasm. We also review the implications that these recently described molecular characteristics may have on risk stratification and treatment of LCH.

Risk organ + LCH gets the one-two punch?

In this issue of Blood, Donadieu et al present what may be the most encouraging data to date on a group of patients with Langerhans cell histiocytosis (LCH), which historically has poor disease-free survival and poor overall survival.

Clinical Characteristics and Treatment of Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a disease caused by clonal proliferation of CD1a+/CD207+ cells that is characterized by a spectrum of varying degrees of organ involvement and dysfunction. Treatment of LCH is risk adapted; patients with single lesions may respond well to local treatment, whereas patients with multi-system disease and risk-organ involvement require more intensive therapy. Although survival for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 30% to 40%. For patients with low-risk disease, although cure is almost universal, disease reactivation rates are in excess of 30%.

Cladribine and cytarabine in refractory multisystem Langerhans cell histiocytosis: results of an international phase 2 study

An international phase 2 study combining cladribine and cytarabine (Ara-C) was initiated for patients with refractory, risk-organ-positive Langerhans cell histiocytosis (LCH) in 2005. The protocol, comprising at least two 5-day courses of Ara-C (1 g/m(2) per day) plus cladribine (9 mg/m(2) per day) followed by maintenance therapy, was administered to 27 patients (median age at diagnosis, 0.7 years; median follow-up, 5.3 years). At inclusion, all patients were refractory after at least 1 course of vinblastine (VBL) plus corticosteroid, all had liver and spleen involvement, and 25 patients had hematologic cytopenia. After 2 courses, disease status was nonactive (n = 2), better (n = 23), or stable (n = 2), with an overall response rate of 92%. Median disease activity scores decreased from 12 at the start of therapy to 3 after 2 courses (P < .0001). During maintenance therapy, 4 patients experienced reactivation in risk organs. There were 4 deaths; 2 were related to therapy toxicity and 2 were related to reactivation. All patients experienced severe toxicity, with World Health Organization grade 4 hematologic toxicity and 6 documented severe infections. The overall 5-year survival rate was 85% (95% confidence interval, 65.2%-94.2%). Thus, the combination of cladribine/Ara-C is effective therapy for refractory multisystem LCH but is associated with high toxicity.

How I treat Langerhans cell histiocytosis

"Langerhans cell histiocytosis" (LCH) describes a spectrum of clinical presentations ranging from a single bone lesion or trivial skin rash to an explosive disseminated disease. Regardless of clinical severity, LCH lesions share the common histology of CD1a(+)/CD207(+) dendritic cells with characteristic morphology among an inflammatory infiltrate. Despite historical uncertainty defining LCH as inflammatory vs neoplastic and incomplete understanding of mechanisms of pathogenesis, clinical outcomes have improved markedly over the past decades through cooperative randomized clinical trials based on empiric therapeutic strategies. Significant advances include recognition of high- and low-risk clinical groups defined by hematopoietic and/or hepatic involvement, and of the importance of optimal intensity and of duration of chemotherapy. Nevertheless, mortality of high-risk patients, disease recurrence, lack of robustly tested salvage strategies, and significant disease morbidity of both high- and low-risk patients remain challenges. Recent discovery of recurrent somatic mutations in mitogen-activated protein kinase pathway genes at critical stages of myeloid hematopoietic differentiation in LCH patients supports redefinition of the disease as a myeloproliferative disorder and provides opportunities to develop novel approaches to diagnosis and therapy.

Haematopoietic stem cell transplantation for refractory Langerhans cell histiocytosis: outcome by intensity of conditioning

Patients with Langerhans cell histiocytosis (LCH) refractory to conventional chemotherapy have a poor outcome. There are currently two promising treatment strategies for high-risk patients: the first involves the combination of 2-chlorodeoxyadenosine and cytarabine; the other approach is allogeneic haematopoietic stem cell transplantation (HSCT). Here we evaluated 87 patients with high-risk LCH who were transplanted between 1990 and 2013. Prior to the year 2000, most patients underwent HSCT following myeloablative conditioning (MAC): only 5 of 20 patients (25%) survived with a high rate (55%) of transplant-related mortality (TRM). After the year 2000 an increasing number of patients underwent HSCT with reduced intensity conditioning (RIC): 49/67 (73%) patients survived, however, the improved survival was not overtly achieved by the introduction of RIC regimens with similar 3-year probability of survival after MAC (77%) and RIC transplantation (71%). There was no significant difference in TRM by conditioning regimen intensity but relapse rates were higher after RIC compared to MAC regimens (28% vs. 8%, P = 0·02), although most patients relapsing after RIC transplantation could be salvaged with further chemotherapy. HSCT may be a curative approach in 3 out of 4 patients with high risk LCH refractory to chemotherapy: the optimal choice of HSCT conditioning remains uncertain.

Interleukin-1 loop model for pathogenesis of Langerhans cell histiocytosis

We propose Langerhans cell histiocytosis (LCH) is an inflammatory process that is prolonged by mutations. We hypothesize that Merkel cell polyomavirus (MCPyV) infection triggers an interleukin-1 (IL-1) activation loop that underlies the pathogenesis of LCH. Langerhans cells (LCs) are antigen presenting cells in the skin. When LCs encounter exogenous antigens, they migrate from the epidermis into draining lymphoid tissues to initiate T-cell activity. It has been proposed that LC migration-related factors, including E-cadherin, matrix metalloproteinase, and Notch ligand induce LCH activity. We found that the tyrosine phosphatase SHP-1, which binds IL-1 receptor-associated kinase 1, is expressed at a significantly higher level in LCH affecting multiple organ systems (MS-LCH) than in LCH affecting a single organ system (SS-LCH). IL-1 stimulates T helper 17 cells and their signature cytokine IL-17 had been a matter of controversy. We detected higher levels of IL-17A receptor expression in MS-LCH than in SS-LCH and proposed an IL-17 endocrine model that could settle the controversy. IL-1 is the first cytokine secreted in response to sensitizers and promotes LC migration from sentinel tissues. Myeloid differentiation primary response 88 (MyD88), downstream of the IL-1 receptor, has functions in both RAS signaling and inflammation, leading to human cell transformation. In 2010, an activating mutation in the B-rapidly accelerated fibrosarcoma gene (BRAF) V600E was found in LCH. This BRAF mutation induces phosphorylation of the extracellular signal-regulated kinase (ERK) that may play an important role with MyD88 in LCH pathogenesis. However, phosphorylated ERK (pERK) is rapidly dephosphorylated by dual specificity phosphatase 6 (DUSP6), and limited proliferation is predicted in BRAF mutant cells. MyD88 binds pERK via its D-domain, thereby preventing pERK-DUSP6 interaction and maintaining ERK in an active, phosphorylated state. We detected MCPyV-DNA in the peripheral blood cells of two out of three patients with LCH in high-risk organs but not in those of patients with LCH in non-high-risk organs (0/12; P = .029). MCPyV infection can trigger precursor LCH cells with BRAF mutation to produce IL-1; the IL-1 loop is amplified in all LCH subclasses. Our model indicates both BRAF mutation and IL-1 loop regulation as potential therapeutic targets.

Progress in understanding the pathogenesis of Langerhans cell histiocytosis: back to Histiocytosis X?

Langerhans cell histiocytosis (LCH), the most common histiocytic disorder, is characterized by the accumulation of CD1A(+) /CD207(+) mononuclear phagocytes within granulomatous lesions that can affect nearly all organ systems. Historically, LCH has been presumed to arise from transformed or pathologically activated epidermal dendritic cells called Langerhans cells. However, new evidence supports a model in which LCH occurs as a consequence of a misguided differentiation programme of myeloid dendritic cell precursors. Genetic, molecular and functional data implicate activation of the ERK signalling pathway at critical stages in myeloid differentiation as an essential and universal driver of LCH pathology. Based on these findings, we propose that LCH should be re-defined as an inflammatory myeloid neoplasia. Increased understanding of LCH pathogenesis will provide opportunities to optimize and personalize therapy through improved risk-stratification, targeted therapy and assessment of therapy response based on specific molecular features and origin of the pathological myeloid cells.

Clinicopathologic characteristics and outcomes of histiocytic and dendritic cell neoplasms: the moffitt cancer center experience over the last twenty five years

Neoplasms of histiocytic and dendritic cells are rare disorders of the lymph node and soft tissues. Because of this rarity, the corresponding biology, prognosis and terminologies are still being better defined and hence historically, these disorders pose clinical and diagnostic challenges. These disorders include Langerhans cell histiocytosis (LCH), histiocytic sarcoma (HS), follicular dendritic cell sarcoma (FDCS), interdigtating cell sarcoma (IDCS), indeterminate cell sarcoma (INDCS), and fibroblastic reticular cell tumors (FRCT). In order to gain a better understanding of the biology, diagnosis, and treatment in these rare disorders we reviewed our cases of these neoplasms over the last twenty five years and the pertinent literature in each of these rare neoplasms. Cases of histiocytic and dendritic cell neoplasms diagnosed between 1989–2014 were identified using our institutional database. Thirty two cases were included in this analysis and were comprised of the following: Langerhans cell histiocytosis (20/32), histiocytic sarcoma (6/32), follicular dendritic cell sarcoma (2/32), interdigitating dendritic cell sarcoma (2/32), indeterminate dendritic cell sarcoma (1/32), and fibroblastic reticular cell tumor (1/32). Median overall survival was not reached in cases with LCH and showed 52 months in cases with HS, 12 months in cases with FDCS, 58 months in cases with IDCS, 13 months in the case of INDCS, and 51 months in the case of FRCT. The majority of patients had surgical resection as initial treatment (n = 18). Five patients had recurrent disease. We conclude that histiocytic and dendritic cell neoplasms are very rare and perplexing disorders that should be diagnosed with a combination of judicious morphology review and a battery of immunohistochemistry to rule out mimics such as carcinoma, lymphoma, neuroendocrine tumors and to better sub-classify these difficult to diagnose lesions. The mainstay of treatment for localized disease remains surgical resection and the role of adjuvant therapy is unclear. In patients with multiple areas of involvement, treatment at tertiary care centers with multimodality treatment is likely needed. Accurate subset diagnosis will contribute to better data as well as treatment outcomes analysis of these rare disorders of adult patients in the future.

Differentiating skin-limited and multisystem Langerhans cell histiocytosis

OBJECTIVE

To identify features associated with multisystem involvement and therapeutic failure in patients with skin Langerhans cell histiocytosis (LCH).

STUDY DESIGN

We reviewed medical records of 71 consecutive patients with LCH with skin involvement evaluated at Texas Children's Hospital and analyzed clinical features, laboratory results, and the presence of circulating cells with the BRAF-V600E mutation with respect to initial staging and clinical outcomes.

RESULTS

Skin disease in patients older than 18 months of age at diagnosis was associated with the presence of multisystem disease (OR, 9.65; 95% CI, 1.17-79.4). Forty percent of patients referred for presumed skin-limited LCH had underlying multisystem involvement, one-half of these with risk-organ involvement. Patients with skin-limited LCH had a 3-year progression-free survival of 89% after initial therapy, and none developed multisystem disease. Patients with skin/multisystem involvement had a 3-year progression-free survival of 44% with vinblastine/prednisone therapy, and risk-organ involvement did not correlate with failure to achieve nonactive disease. Circulating cells with BRAF-V600E were detected at higher frequency in patients with multisystem involvement (8 of 11 skin/multisystem vs 1 of 13 skin-limited; P = .002).

CONCLUSION

Skin-limited LCH necessitates infrequent therapeutic intervention and has a lower risk of progression relative to skin plus multisystem LCH. The less-aggressive clinical course and lack of circulating cells with the BRAF-V600E mutation in skin-limited LCH suggest a different mechanism of disease origin compared with multisystem or risk-organ disease.

A single case of rosai-dorfman disease marked by pathologic fractures, kidney failure, and liver cirrhosis treated with single-agent cladribine

Rosai–Dorfman disease (RDD) is a proliferative histiocytic disorder of unknown etiology, which is characterized by sinus histiocytosis with massive lymphadenopathy (1). In most cases, RDD has a benign course and treatment is not necessary. However, severe cases of RDD require treatment, and the treatment strategy is determined on the basis of the severity of the disease or the extranodal involvement of vital organs. We report a single case of RDD with atypical presentation of persistent constitutional symptoms, progressing pathologic fractures, and end-organ dysfunction, including acute kidney failure and liver cirrhosis with esophageal varices.

Recent advances in Langerhans cell histiocytosis

The purpose of this review is to provide an updated overview of the pathogenesis and treatment of Langerhans cell histiocytosis (LCH). The pathogenesis of LCH remains obscure and the optimal treatment for LCH has not been established, although incremental progress has been made. Proinflammatory cytokines and chemokines are known to play a role in LCH, which suggests that LCH is an immune disorder. However, the oncogenic BRAF mutation is also detected in more than half of LCH patients, which suggests that LCH is a neoplastic disorder. Remaining major issues in the treatment of LCH are how to rescue patients who have risk-organ involvement but do not respond to first-line therapy, the optimal treatment for the orphan disease of multifocal adult LCH, and how to reduce and treat central nervous system-related consequences, such as central diabetes insipidus and neurodegeneration. More research is needed to better understand the pathogenesis of this disease and to resolve the treatment issues.

Updates on histiocytic disorders

Histiocytic disorders are rare entities that are becoming more recognized as our understanding of the molecular pathogenesis lead to novel diagnostic tests and targeted drug development. A symposium held at the American Society of Pediatric Hematology/Oncology (ASPHO) 2013 Annual Meeting discussed new insights into histiocytic disorders. This review highlights the symposium presentations, divided into three sections encompassing Langerhans cell histiocytosis (LCH), hemophagocytic lymphohistiocytosis (HLH) and Rosai Dorfman disease (RDD) including subsections on pathogenesis, clinical diagnostic criteria and novel insights into treatment. Details of other histiocytic disorders as well as the standard treatment guidelines have been published elsewhere and are beyond the scope of this discussion [Haupt et al. (2013). Pediatr Blood Cancer 60:175-184; Henter et al. (2007). Pediatr Blood Cancer 48:124-131].

Blood spotlight on Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease affecting people of any age, with widely variable clinical manifestations and different outcomes. The precise chain of events driving lesional granuloma formation has remained elusive for many years. There is evidence for inherited predisposition to and derangement of apoptosis and inflammation in lesional dendritic cells. Recently somatic BRAF(V600E) mutation in myeloid precursor dendritic cells was associated with the more aggressive form of the disease, although the same mutation in a more differentiated dendritic cell might drive a less aggressive disease. Whether this picture convincingly put LCH in the field of myeloid neoplasm remains to be determined. Altogether, these findings suggest that future therapeutic strategy might incorporate a screening of this genetic mutation for high-risk patients potentially suitable for target therapy.

BRAF-V600E expression in precursor versus differentiated dendritic cells defines clinically distinct LCH risk groups

Langerhans cell histiocytosis (LCH) is a clonal disorder with elusive etiology, characterized by the accumulation of CD207(+) dendritic cells (DCs) in inflammatory lesions. Recurrent BRAF-V600E mutations have been reported in LCH. In this study, lesions from 100 patients were genotyped, and 64% carried the BRAF-V600E mutation within infiltrating CD207(+) DCs. BRAF-V600E expression in tissue DCs did not define specific clinical risk groups but was associated with increased risk of recurrence. Strikingly, we found that patients with active, high-risk LCH also carried BRAF-V600E in circulating CD11c(+) and CD14(+) fractions and in bone marrow (BM) CD34(+) hematopoietic cell progenitors, whereas the mutation was restricted to lesional CD207(+) DC in low-risk LCH patients. Importantly, BRAF-V600E expression in DCs was sufficient to drive LCH-like disease in mice. Consistent with our findings in humans, expression of BRAF-V600E in BM DC progenitors recapitulated many features of the human high-risk LCH, whereas BRAF-V600E expression in differentiated DCs more closely resembled low-risk LCH. We therefore propose classification of LCH as a myeloid neoplasia and hypothesize that high-risk LCH arises from somatic mutation of a hematopoietic progenitor, whereas low-risk disease arises from somatic mutation of tissue-restricted precursor DCs.

Clofarabine salvage therapy in refractory multifocal histiocytic disorders, including Langerhans cell histiocytosis, juvenile xanthogranuloma and Rosai-Dorfman disease

BACKGROUND

Existing therapies for recurrent or refractory histiocytoses, including Langerhans cell histiocytosis (LCH), juvenile xanthogranuloma (JXG), and Rosai-Dorfman disease (RDD), have limited effectiveness. We report our experience with using clofarabine as therapy in children with recurrent or refractory histiocytic disorders, including LCH (11 patients), systemic JXG (4 patients), and RDD (3 patients).

METHODS

Patients treated with clofarabine for LCH, JXG, or RDD by Texas Children's Hospital physicians or collaborators between May 2011 and January 2013 were reviewed for response and toxicity.

RESULTS

Patients were treated with a median of three chemotherapeutic regimens prior to clofarabine. Clofarabine was typically administered at 25 mg/m(2) /day for 5 days. Cycles were administered every 28 days for a median of six cycles (range: 2-8 cycles). Seventeen of 18 patients are alive. All surviving patients showed demonstrable improvement after two to four cycles of therapy, with 11 (61%) complete responses, 4 (22%) partial responses, and 2 patients still receiving therapy. Five patients experienced disease recurrence, but three of these subsequently achieved complete remission. All patients with JXG and RDD had complete or partial response at conclusion of therapy. Side effects included neutropenia in all patients. Recurring but sporadic toxicities included prolonged neutropenia, severe vomiting, and bacterial infections.

CONCLUSION

Clofarabine has activity against LCH, JXG, and RDD in heavily pretreated patients, but prospective multi-center trials are warranted to determine long-term efficacy, optimal dosing, and late toxicity of clofarabine in this population.

Management of adult Langerhans cell histiocytosis based on the characteristic clinical features

To find out the most appropriate management, clinical features of 18 cases of adult multisystem langerhans cell histiocytosis (LCH) have been analyzed. The patients comprising of 9 males and 9 females were median age of 36 years, ranging from 18-53 years at diagnosis. Regarding the initial symptoms, 7 patients (2 males and 5 females) showed central diabetes insipidus (CDI) and other endocrine symptoms with thickened pituitary stalk or a mass at the hypothalamic region. Additional 2 patients initiated the disease with CDI with no immediate diagnosis. In the remaining patients, the disease begun with single (n = 3) or multiple (n = 1) spinal bone lesion(s) in 4 patients (all males), with multiple bone lesions in 3 patients (1 male and 2 females), with single skull lesion in one female patient and with ambiguous symptoms including hypothyroidism in the remaining one male patient. We also recognized the correlation between pregnancy/childbirth and LCH in 4 patients. In terms of treatment, 9 patients received systemic immuno-chemotherapy alone, of which the majority received vinblastine-based chemotherapy while 4 received 2-chlorodeoxyadenosine. Five had a combination of immuno-chemotherapy with surgical resection or radiotherapy, 2 had immunotherapy alone, 2 had surgical resection followed by observation alone to date. Three patients received hematopoietic stem cell transplantation after extensive chemotherapy. In terms of outcome, 15 patients are alive (9 with active disease, 6 without active disease), with a median of 66 mo (range 17-166 mo), two died of disease while the remaining 1 lost to follow-up. Based on these results, we think that early diagnosis and rapid introduction of appropriate treatment are essential, in order to overcome the problems relevant to adult LCH.

Clofarabine salvage therapy for refractory high-risk langerhans cell histiocytosis

Pediatric patients with refractory multisystem Langerhans cell histiocytosis (LCH) have a poor prognosis despite aggressive chemotherapy. Salvage therapy with cytarabine and cladribine has shown promise as an effective treatment but is associated with significant toxicity. A previous report described two patients with refractory LCH who had a rapid response to single-agent clofarabine with minimal toxicity. In this report, we describe four children with refractory, risk-organ-positive LCH who were treated with clofarabine and provide follow-up for the two previously reported cases. The results support development of a formal trial evaluating clofarabine as front-line salvage for refractory LCH.

Therapy prolongation improves outcome in multisystem Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH)-III tested risk-adjusted, intensified, longer treatment of multisystem LCH (MS-LCH), for which optimal therapy has been elusive. Stratified by risk organ involvement (high [RO+] or low [RO-] risk groups), > 400 patients were randomized. RO+ patients received 1 to 2 six-week courses of vinblastine+prednisone (Arm A) or vinblastine + prednisone + methotrexate (Arm B). Response triggered milder continuation therapy with the same combinations, plus 6-mercaptopurine, for 12 months total treatment. 6/12-week response rates (mean, 71%) and 5-year survival (84%) and reactivation rates (27%) were similar in both arms. Notably, historical comparisons revealed survival superior to that of identically stratified RO+ patients treated for 6 months in predecessor trials LCH-I (62%) or LCH-II (69%, P < .001), and lower 5-year reactivation rates than in LCH-I (55%) or LCH-II (44%, P < .001). RO- patients received vinblastine+prednisone throughout. Response by 6 weeks triggered randomization to 6 or 12 months total treatment. Significantly lower 5-year reactivation rates characterized the 12-month Arm D (37%) compared with 6-month Arm C (54%, P = .03) or to 6-month schedules in LCH-I (52%) and LCH-II (48%, P < .001). Thus, prolonging treatment decreased RO- patient reactivations in LCH-III, and although methotrexate added no benefit, RO+ patient survival and reactivation rates have substantially improved in the 3 sequential trials. (Trial No. NCT00276757 www.ClinicalTrials.gov).

Langerhans cell histiocytosis (LCH): guidelines for diagnosis, clinical work-up, and treatment for patients till the age of 18 years

These guidelines for the management of patients up to 18 years with Langerhans cell histiocytosis (LCH) have been set up by a group of experts involved in the Euro Histio Net project who participated in national or international studies and in peer reviewed publications. Existing guidelines were reviewed and changed where new evidence was available in the literature up to 2012. Data and publications have been ranked according to evidence based medicine and when there was a lack of published data, consensus between experts was sought. Guidelines for diagnosis, initial clinical work-up, and treatment and long-term follow-up of LCH patients are presented.

Use of radiation in treatment of central nervous system juvenile xanthogranulomatosis

Juvenile xanthogranulomatosis (JXG) represents a subset of non-Langerhan cell histiocytosis that typically manifests in younger children with skin lesions. Unresectable central nervous system (CNS) disease is difficult to treat. We describe the case of a 13-year-old successfully treated with adjuvant radiation therapy for symptomatic intracranial and leptomeningeal JXG. An extensive literature review was performed to identify all previous CNS JXG cases utilizing radiation, of which six of eight total patients demonstrated temporary or long-term improvement of neurologic disease. This suggests that radiation should be considered in cases unresponsive to conventional treatment options.