Lost in translation: a neglected mTOR target for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a cystic lung disease of women resulting from mutations in tuberous sclerosis complex (TSC) genes that suppress the mammalian target of rapamycin complex 1 (mTORC1) pathway. mTORC1 activation enhances a plethora of anabolic cellular functions, mainly via the activation of mRNA translation through stimulation of ribosomal protein S6 kinase (S6K1)/ribosomal protein S6 (S6) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1)/eukaryotic translation initiation factor 4E (eIF4E). Rapamycin (sirolimus), an allosteric inhibitor of mTORC1, stabilises lung function in many but not all LAM patients and, upon cessation of the drug, disease progression resumes. At clinically tolerable concentrations, rapamycin potently inhibits the ribosomal S6K1/S6 translation ribosome biogenesis and elongation axis, but not the translation 4E-BP1/eIF4E initiation axis. In this mini-review, we propose that inhibition of mTORC1-driven translation initiation is an obvious but underappreciated therapeutic strategy in LAM, TSC and other mTORC1-driven diseases.

Tissue-Engineered Disease Modeling of Lymphangioleiomyomatosis Exposes a Therapeutic Vulnerability to HDAC Inhibition

Lymphangioleiomyomatosis (LAM) is a rare disease involving cystic lung destruction by invasive LAM cells. These cells harbor loss-of-function mutations in TSC2, conferring hyperactive mTORC1 signaling. Here, tissue engineering tools are employed to model LAM and identify new therapeutic candidates. Biomimetic hydrogel culture of LAM cells is found to recapitulate the molecular and phenotypic characteristics of human disease more faithfully than culture on plastic. A 3D drug screen is conducted, identifying histone deacetylase (HDAC) inhibitors as anti-invasive agents that are also selectively cytotoxic toward TSC2-/- cells. The anti-invasive effects of HDAC inhibitors are independent of genotype, while selective cell death is mTORC1-dependent and mediated by apoptosis. Genotype-selective cytotoxicity is seen exclusively in hydrogel culture due to potentiated differential mTORC1 signaling, a feature that is abrogated in cell culture on plastic. Importantly, HDAC inhibitors block invasion and selectively eradicate LAM cells in vivo in zebrafish xenografts. These findings demonstrate that tissue-engineered disease modeling exposes a physiologically relevant therapeutic vulnerability that would be otherwise missed by conventional culture on plastic. This work substantiates HDAC inhibitors as possible therapeutic candidates for the treatment of patients with LAM and requires further study.

Sporadic Lymphangioleiomyomatosis Disease: A Case Report

Pulmonary Lymphangioleiomyomatosis (LAM) is a rare disease of the lung and lymphatic system that primarily affects women of childbearing age. LAM is a progressive disease with a terrible prognosis, which worsens over time and is extremely difficult to treat. In this study, we discuss the case of a 31-year-old woman with LAM who was initially misdiagnosed with leiomyoma and the way that led to a true diagnosis and effective treatment. Following a precise diagnosis based on comprehensive clinical data and particular immunohistochemical tests, sirolimus treatment was initiated, and the patient entirely responded to the treatment. This case report demonstrated that LAM is an uncommon condition that is challenging to diagnose, which causes its treatment to be delayed.

Predicting Individualized Lung Disease Progression in Treatment-Naive Patients With Lymphangioleiomyomatosis

BACKGROUND

Lung function decline varies significantly in patients with lymphangioleiomyomatosis (LAM), impeding individualized clinical decision-making.

RESEARCH QUESTION

Can we aid individualized decision-making in LAM by developing a dynamic prediction model that can estimate the probability of clinically relevant FEV1 decline in patients with LAM before treatment initiation?

STUDY DESIGN AND METHODS

Patients observed in the US National Heart, Lung, and Blood Institute (NHLBI) Lymphangioleiomyomatosis Registry were included. Using routinely available variables such as age at diagnosis, menopausal status, and baseline lung function (FEV1 and diffusing capacity of the lungs for carbon monoxide [Dlco]), we used novel stochastic modeling and evaluated predictive probabilities for clinically relevant drops in FEV1. We formed predictive probabilities of transplant-free survival by jointly modeling longitudinal FEV1 and lung transplantation or death events. External validation used the UK Lymphangioleiomyomatosis Natural History cohort.

RESULTS

Analysis of the NHLBI Lymphangioleiomyomatosis Registry and UK Lymphangioleiomyomatosis Natural History cohorts consisted of 216 and 185 individuals, respectively. We derived a joint model that accurately estimated the risk of future lung function decline and 5-year probabilities of transplant-free survival in patients with LAM not taking sirolimus (area under the receiver operating characteristic curve [AUC], approximately 0.80). The prediction model provided estimates of forecasted FEV1, rate of FEV1 decline, and probabilities for risk of prolonged drops in FEV1 for untreated patients with LAM with a high degree of accuracy (AUC > 0.80) for the derivation cohort as well as the validation cohort. Our tool is freely accessible at: https://anushkapalipana.shinyapps.io/testapp_v2/.

INTERPRETATION

Longitudinal modeling of routine clinical data can allow individualized LAM prognostication and assist in decision-making regarding the timing of treatment initiation.

Protease activity sensors enable real-time treatment response monitoring in lymphangioleiomyomatosis

BACKGROUND

Biomarkers of disease progression and treatment response are urgently needed for patients with lymphangioleiomyomatosis (LAM). Activity-based nanosensors, an emerging biosensor class, detect dysregulated proteases in vivo and release a reporter to provide a urinary readout of disease. Because proteases are dysregulated in LAM and may directly contribute to lung function decline, activity-based nanosensors may enable quantitative, real-time monitoring of LAM progression and treatment response. We aimed to assess the diagnostic utility of activity-based nanosensors in a pre-clinical model of pulmonary LAM.

METHODS

Tsc2-null cells were injected intravenously into female nude mice to establish a mouse model of pulmonary LAM. A library of 14 activity-based nanosensors, designed to detect proteases across multiple catalytic classes, was administered into the lungs of LAM mice and healthy controls, urine was collected, and mass spectrometry was performed to measure nanosensor cleavage products. Mice were then treated with rapamycin and monitored with activity-based nanosensors. Machine learning was performed to distinguish diseased from healthy and treated from untreated mice.

RESULTS

Multiple activity-based nanosensors (PP03 (cleaved by metallo, aspartic and cysteine proteases), padjusted<0.0001; PP10 (cleaved by serine, aspartic and cysteine proteases), padjusted=0.017)) were differentially cleaved in diseased and healthy lungs, enabling strong classification with a machine learning model (area under the curve (AUC) 0.95 from healthy). Within 2 days after rapamycin initiation, we observed normalisation of PP03 and PP10 cleavage, and machine learning enabled accurate classification of treatment response (AUC 0.94 from untreated).

CONCLUSIONS

Activity-based nanosensors enable noninvasive, real-time monitoring of disease burden and treatment response in a pre-clinical model of LAM.

Lung-selective mRNA delivery of synthetic lipid nanoparticles for the treatment of pulmonary lymphangioleiomyomatosis

Safe and efficacious systemic delivery of messenger RNA (mRNA) to specific organs and cells in vivo remains the major challenge in the development of mRNA-based therapeutics. Targeting of systemically administered lipid nanoparticles (LNPs) coformulated with mRNA has largely been confined to the liver and spleen. Using a library screening approach, we identified that N-series LNPs (containing an amide bond in the tail) are capable of selectively delivering mRNA to the mouse lung, in contrast to our previous discovery that O-series LNPs (containing an ester bond in the tail) that tend to deliver mRNA to the liver. We analyzed the protein corona on the liver- and lung-targeted LNPs using liquid chromatography-mass spectrometry and identified a group of unique plasma proteins specifically absorbed onto the surface that may contribute to the targetability of these LNPs. Different pulmonary cell types can also be targeted by simply tuning the headgroup structure of N-series LNPs. Importantly, we demonstrate here the success of LNP-based RNA therapy in a preclinical model of lymphangioleiomyomatosis (LAM), a destructive lung disease caused by loss-of-function mutations in the Tsc2 gene. Our lung-targeting LNP exhibited highly efficient delivery of the mouse tuberous sclerosis complex 2 (Tsc2) mRNA for the restoration of TSC2 tumor suppressor in tumor and achieved remarkable therapeutic effect in reducing tumor burden. This research establishes mRNA LNPs as a promising therapeutic intervention for the treatment of LAM.

Histamine signaling and metabolism identify potential biomarkers and therapies for lymphangioleiomyomatosis

Inhibition of mTOR is the standard of care for lymphangioleiomyomatosis (LAM). However, this therapy has variable tolerability and some patients show progressive decline of lung function despite treatment. LAM diagnosis and monitoring can also be challenging due to the heterogeneity of symptoms and insufficiency of non-invasive tests. Here, we propose monoamine-derived biomarkers that provide preclinical evidence for novel therapeutic approaches. The major histamine-derived metabolite methylimidazoleacetic acid (MIAA) is relatively more abundant in LAM plasma, and MIAA values are independent of VEGF-D. Higher levels of histamine are associated with poorer lung function and greater disease burden. Molecular and cellular analyses, and metabolic profiling confirmed active histamine signaling and metabolism. LAM tumorigenesis is reduced using approved drugs targeting monoamine oxidases A/B (clorgyline and rasagiline) or histamine H1 receptor (loratadine), and loratadine synergizes with rapamycin. Depletion of Maoa or Hrh1 expression, and administration of an L-histidine analog, or a low L-histidine diet, also reduce LAM tumorigenesis. These findings extend our knowledge of LAM biology and suggest possible ways of improving disease management.

Connectivity Map Analysis of a Single-Cell RNA-Sequencing -Derived Transcriptional Signature of mTOR Signaling

In the connectivity map (CMap) approach to drug repositioning and development, transcriptional signature of disease is constructed by differential gene expression analysis between the diseased tissue or cells and the control. The negative correlation between the transcriptional disease signature and the transcriptional signature of the drug, or a bioactive compound, is assumed to indicate its ability to “reverse” the disease process. A major limitation of traditional CMaP analysis is the use of signatures derived from bulk disease tissues. Since the key driver pathways are most likely dysregulated in only a subset of cells, the “averaged” transcriptional signatures resulting from bulk analysis lack the resolution to effectively identify effective therapeutic agents. The use of single-cell RNA-seq (scRNA-seq) transcriptomic assay facilitates construction of disease signatures that are specific to individual cell types, but methods for using scRNA-seq data in the context of CMaP analysis are lacking. Lymphangioleiomyomatosis (LAM) mutations in TSC1 or TSC2 genes result in the activation of the mTOR complex 1 (mTORC1). The mTORC1 inhibitor Sirolimus is the only FDA-approved drug to treat LAM. Novel therapies for LAM are urgently needed as the disease recurs with discontinuation of the treatment and some patients are insensitive to the drug. We developed methods for constructing disease transcriptional signatures and CMaP analysis using scRNA-seq profiling and applied them in the analysis of scRNA-seq data of lung tissue from naïve and sirolimus-treated LAM patients. New methods successfully implicated mTORC1 inhibitors, including Sirolimus, as capable of reverting the LAM transcriptional signatures. The CMaP analysis mimicking standard bulk-tissue approach failed to detect any connection between the LAM signature and mTORC1 signaling. This indicates that the precise signature derived from scRNA-seq data using our methods is the crucial difference between the success and the failure to identify effective therapeutic treatments in CMaP analysis.

CrossTORC and WNTegration in Disease: Focus on Lymphangioleiomyomatosis

The mechanistic target of rapamycin (mTOR) and wingless-related integration site (Wnt) signal transduction networks are evolutionarily conserved mammalian growth and cellular development networks. Most cells express many of the proteins in both pathways, and this review will briefly describe only the key proteins and their intra- and extracellular crosstalk. These complex interactions will be discussed in relation to cancer development, drug resistance, and stem cell exhaustion. This review will also highlight the tumor-suppressive tuberous sclerosis complex (TSC) mutated, mTOR-hyperactive lung disease of women, lymphangioleiomyomatosis (LAM). We will summarize recent advances in the targeting of these pathways by monotherapy or combination therapy, as well as future potential treatments.

mTORC1 activation in lung mesenchyme drives sex- and age-dependent pulmonary structure and function decline

Lymphangioleiomyomatosis (LAM) is a rare fatal cystic lung disease due to bi-allelic inactivating mutations in tuberous sclerosis complex (TSC1/TSC2) genes coding for suppressors of the mechanistic target of rapamycin complex 1 (mTORC1). The origin of LAM cells is still unknown. Here, we profile a LAM lung compared to an age- and sex-matched healthy control lung as a hypothesis-generating approach to identify cell subtypes that are specific to LAM. Our single-cell RNA sequencing (scRNA-seq) analysis reveals novel mesenchymal and transitional alveolar epithelial states unique to LAM lung. This analysis identifies a mesenchymal cell hub coordinating the LAM disease phenotype. Mesenchymal-restricted deletion of Tsc2 in the mouse lung produces a mTORC1-driven pulmonary phenotype, with a progressive disruption of alveolar structure, a decline in pulmonary function, increase of rapamycin-sensitive expression of WNT ligands, and profound female-specific changes in mesenchymal and epithelial lung cell gene expression. Genetic inactivation of WNT signaling reverses age-dependent changes of mTORC1-driven lung phenotype, but WNT activation alone in lung mesenchyme is not sufficient for the development of mouse LAM-like phenotype. The alterations in gene expression are driven by distinctive crosstalk between mesenchymal and epithelial subsets of cells observed in mesenchymal Tsc2-deficient lungs. This study identifies sex- and age-specific gene changes in the mTORC1-activated lung mesenchyme and establishes the importance of the WNT signaling pathway in the mTORC1-driven lung phenotype.

Serum vascular endothelial growth factor-D as a diagnostic and therapeutic biomarker for lymphangioleiomyomatosis

BACKGROUND

In lymphangioleiomyomatosis (LAM), tuberous sclerosis gene mutations activate the mechanistic target of the rapamycin pathway, resulting in vascular endothelial growth factor-D (VEGF-D) overproduction. While the utility of serum VEGF-D testing for the diagnosis of LAM is outlined in ATS/JRS LAM Guidelines, the assay has not been fully validated for Asian populations. Our aims were to validate serum VEGF-D testing in Japan, by directly comparing measurements in Japan and the U.S., determining the diagnostic cut-off for serum VEGF-D levels among the Japanese women with typical thin walled cystic change on CT, and determining the performance of VEGF-D as a prognostic biomarker.

SUBJECTS AND METHODS

We determined serum VEGF-D levels from 108 LAM patients, 14 disease controls, and 51 healthy volunteers from the Japanese population. Measurements of 61 LAM patients were compared to those from the principal VEGF-D laboratory in the U.S at Cincinnati Children's Hospital Medical Center. We correlated baseline serum VEGF-D levels with baseline and longitudinal clinical data to determine how pregnancy, sirolimus or gonadotrophin-releasing hormone (GnRH) agonists influence serum VEGF-D levels.

RESULTS

Serum VEGF-D measurements in Japan and the U.S. were very similar. Baseline serum VEGF-D levels effectively distinguished LAM from other diseases and healthy volunteers at a cut-off level of 645 pg/ml and were diagnostically specific at 800 pg/ml, consistent with the recommendations of the ATS/JRS LAM Guidelines. Baseline serum VEGF-D correlated negatively with the DLco baseline % predicted and with the annual decrease in DLco % predicted. There was no significant association between baseline serum VEGF-D level and the outcomes of death or transplant. Serum VEGF-D levels markedly decreased during treatment with sirolimus, but not with GnRH analogues. Serum VEGF-D levels of most LAM patients did not increase over time, and neither pregnancy nor menopause significantly modulated serum VEGF-D levels.

CONCLUSIONS

Serum VEGF-D is a useful diagnostic and therapeutic biomarker for LAM. Satisfactory precision and international inter-laboratory agreement of the clinical assay support VEGF-D recommendations in the ATS/JRS LAM Guidelines for the Japanese population.

Successful Sirolimus Treatment of Lymphangioleiomyomatosis in a Hepatitis B Virus Carrier

A 34-year-old woman experiencing shortness of breath was referred to our hospital. The patient was diagnosed with sporadic lymphangioleiomyomatosis based on the observation of bilateral diffuse multiple thin-walled cysts on computed tomography of the chest, chylous effusion, elevated serum vascular endothelial growth factor-D levels and transbronchial biopsy findings. This patient was a hepatitis B virus (HBV) carrier. Treatment with 1 mg daily of sirolimus was started after HBV DNA was brought below the cut-off level using entecavir. Sirolimus was effective, as the chylous effusion resolved completely and the dyspnea improved. The sirolimus dosage was increased to 2 mg daily without causing HBV reactivation.

Immune Checkpoint Ligand PD-L1 Is Upregulated in Pulmonary Lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis (LAM) is a slow-progressing metastatic disease that is driven by mutations in the tumor suppressor tuberous sclerosis complex 1/2 (TSC1/2). Rapamycin inhibits LAM cell proliferation and is the only approved treatment, but it cannot cause the regression of existing lesions and can only stabilize the disease. However, in other cancers, immunotherapies such as checkpoint blockade against PD-1 and its ligand PD-L1 have shown promise in causing tumor regression and even curing some patients. Thus, we asked whether PD-L1 has a role in LAM progression. In vitro, PD-L1 expression in murine Tsc2-null cells is unaffected by mTOR inhibition with torin but can be upregulated by IFN-γ. Using immunohistochemistry and single-cell flow cytometry, we found increased PD-L1 expression both in human lung tissue from patients with LAM and in Tsc2-null lesions in a murine model of LAM. In this model, PD-L1 is highly expressed in the lung by antigen-presenting and stromal cells, and activated T cells expressing PD-1 infiltrate the affected lung. In vivo treatment with anti-PD-1 antibody significantly prolongs mouse survival in the model of LAM. Together, these data demonstrate that PD-1/PD-L1-mediated immunosuppression may occur in LAM, and suggest new opportunities for therapeutic targeting that may provide benefits beyond those of rapamycin.

Angiomyolipoma rebound tumor growth after discontinuation of everolimus in patients with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis

Introduction

The EXIST-2 (NCT00790400) study demonstrated the superiority of everolimus over placebo for the treatment of renal angiomyolipomas associated with tuberous sclerosis complex (TSC) or sporadic lymphangioleiomyomatosis (LAM). This post hoc analysis of EXIST-2 study aimed to assess angiomyolipoma tumor behavior among patients who submitted to continued radiographic examination following discontinuation of everolimus in the noninterventional follow-up phase.

Methods

For patients who discontinued everolimus at the completion of extension phase for reasons other than angiomyolipoma progression, a single CT/MRI scan of the kidney was collected after 1 year of treatment discontinuation. Changes from baseline and from the time of everolimus discontinuation in the sum of volumes of target angiomyolipoma lesions were assessed in the non-interventional follow-up phase (data cutoff date, November 6, 2015).

Results

Of the 112 patients who received ≥1 dose of everolimus and discontinued treatment by the end of extension phase, 34 (30.4%) were eligible for participation in the non-interventional follow-up phase. Sixteen of 34 patients were evaluable for angiomyolipoma tumor behavior as they had at least one valid efficacy assessment (i.e. kidney CT/MRI scan) after everolimus discontinuation. During the non-interventional follow-up phase, compared with baseline, two patients (12.5%) experienced angiomyolipoma progression (angiomyolipoma-related bleeding [n = 1], increased kidney volume [n = 1]). Five patients out of 16 (31.3%) experienced angiomyolipoma progression when compared with the angiomyolipoma tumor assessment at everolimus discontinuation. The median (range) percentage change in angiomyolipoma tumor volume (cm³) from baseline was −70.56 (−88.30; −49.64) at time of everolimus discontinuation (n = 11), and −50.55 (−79.40; −23.16) at week 48 (n = 7) after discontinuation of everolimus. One patient death was reported due to angiomyolipoma hemorrhage.

Conclusions

Angiomyolipoma lesions displayed an increase in volume following discontinuation of everolimus in patients with renal angiomyolipoma or sporadic LAM associated with TSC, but there was no evidence of rapid regrowth.

Trial registration

ClinicalTrials.gov NCT00790400

Everolimus long-term use in patients with tuberous sclerosis complex: Four-year update of the EXIST-2 study

OBJECTIVES

We examined the long-term effects of everolimus in patients with renal angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis.

METHODS

Following favorable results from the double-blind core phase of EXIST-2 (NCT00790400), patients were allowed to receive open-label everolimus (extension phase). Patients initially randomly assigned to everolimus continued on the same dose; those who were receiving placebo crossed over to everolimus 10 mg/day. Dose modifications were based on tolerability. The primary end point was angiomyolipoma response rate, defined as a ≥50% reduction from baseline in the sum volume of target renal angiomyolipomas in the absence of new target angiomyolipomas, kidney volume increase of >20% from nadir, and angiomyolipoma-related bleeding grade ≥2. The key secondary end point was safety.

RESULTS

Of the 112 patients who received ≥1 dose of everolimus, 58% (95% CI, 48.3% to 67.3%) achieved angiomyolipoma response. Almost all patients (97%) experienced reduction in renal lesion volumes at some point during the study period. Median duration of everolimus exposure was 46.9 months. Sixteen (14.3%) patients experienced angiomyolipoma progression at some point in the study. No angiomyolipoma-related bleeding or nephrectomies were reported. One patient on everolimus underwent embolization for worsening right flank pain. Subependymal giant cell astrocytoma lesion response was achieved in 48% of patients and skin lesion response in 68% of patients. The most common adverse events suspected to be treatment-related were stomatitis (42%), hypercholesterolemia (30.4%), acne (25.9%), aphthous stomatitis and nasopharyngitis (each 21.4%). Ten (8.9%) patients withdrew because of an adverse event. Renal function remained stable, and the frequency of emergent adverse events generally decreased over time.

CONCLUSIONS

Everolimus treatment remained safe and effective over approximately 4 years. The overall risk/benefit assessment supports the use of everolimus as a viable treatment option for angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00790400.

Pelvic lymphangioleiomyomatosis treated successfully with everolimus: Two case reports with literature review

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare disease affecting young women caused by abnormal proliferation of smooth muscle-like cells (LAM cells) in the lungs and extrapulmonary sites (extrapulmonary LAM). The objective of this case series is to demonstrate marked regression in 2 cases of retroperitoneal LAM after treatment with everolimus, an mTOR inhibitor.

METHODS

We enrolled 2 cases with large volume, extrapulmonary pelvic LAM, and evaluated them with contrast-enhanced abdominal computed tomographic (CT) scans at presentation and serially during treatment with everolimus. Results were objectively quantified using the Response Evaluation Criteria in Solid Tumors, RECIST, Version 1.1.

RESULTS

After 12 to 18 months of treatment with everolimus, both patients showed substantial reduction in the volume of their tumors. The first had about 50% regression of the pelvic LAM and renal angiomyolipoma (AML). The second patient had extensive abdomino-pelvic LAM which after treatment showed complete remission. Both patients have not demonstrated disease progression after nearly 4 and 2 years of follow-up, respectively.

CONCLUSIONS

This case series demonstrates the enormous value of mTOR inhibitors (specifically everolimus) in the management of extrapulmonary pelvic LAM, of which there is no effective treatment currently available.

Diagnostic and Treatment Monitoring Potential of Serum Vascular Endothelial Growth Factor-D in Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare multisystem disease occurring almost exclusively in premenopausal women and characterized by cystic lung destruction, abdominal tumors (renal angiomyolipomas (AML)), and involvement of the axial lymphatics (adenopathy, lymphangioleiomyomas). Serum vascular endothelial growth factor-D (VEGF-D), a lymphangiogenic factor, has been recently considered as a novel marker for LAM. Herein we report the diagnostic and differential diagnostic value of serum VEGF-D in LAM patients and evaluate the change of serum VEGF-D levels before and after treatment with sirolimus. The study group included 66 patients with LAM (47 definite LAM and 19 probable LAM based on European Respiratory Society guidelines), 14 patients with other polycystic lung diseases, and 20 healthy female controls. Serum VEGF-D levels were quantified by enzyme-linked immunoassay (ELISA). Serum VEGF-D levels were significantly increased in definite LAM patients compared with healthy controls (3890.3±373.3 pg/ml vs. 413.3±33.2 pg/ml, p<0.05). The optimal cutoff point for LAM diagnosis was 692.5 pg/ml with sensitivity of 97.9% and specificity of 100%. In probable LAM patients, serum VEGF-D levels were all greater than 692.5 pg/ml. Serum VEGF-D levels were significantly increased in definite LAM patients who had chylothorax compared with those without chylothorax (5153.9±598.3 pg/ml vs. 2869.8±372.8 pg/ml, p<0.05). But serum VEGF-D levels in LAM patients with/without pneumothorax, AML, and lymphangioleiomyomas were not significantly changed. Serum VEGF-D levels in definite LAM patients and patients with other cystic lung diseases were 3890.3±373.3 pg/ml and 412.6±27.5 pg/ml, respectively (p <0.05). We determined an optimal cutoff value of 688.5pg/ml, resulting in sensitivity of 97.9% and specificity of 100%. Following a median of 12-month treatment with sirolimus, serum VEGF-D levels decreased from 3135.0±909.4 pg/ml to 1731.8±621.2 pg/ml and symptoms improved. Our study found that serum VEGF-D levels were significantly higher in LAM patients compared with healthy controls and patients with other polycystic lung diseases and that the levels were further increased when complicated by chylothorax. Serum VEGF-D levels may be useful for diagnosis and differential diagnosis with high specificity and sensitivity as well as for following treatment response with sirolimus.

Long-term stable lung function and second uncomplicated pregnancy on sirolimus in lymphangioleiomyomatosis (LAM)

We present a patient with lymphangioleiomyomatosis (LAM) on long-term sirolimus (now 79 months) who has had a second successful pregnancy. The second pregnancy on uninterrupted low-dose sirolimus (plasma levels 3-5 mg/L) was uncomplicated both with respect to mother and child suggesting that low-dose sirolimus might be safe in selected pregnant patients with stable LAM. The long-term time course in this patient is in agreement with recent reports of a long-term beneficial effect of sirolimus in LAM. In this patient, the pregnancies did not seem to impair the long-term improvement of lung-function on sirolimus.

SUCCESSFUL TREATMENT OF PULMONARY AND LYMPHATIC MANIFESTATIONS OF LYMPHANGIOLEIOMYOMATOSIS WITH SIROLIMUS

Lymphangioleiomyomatosis (LAM) is a rare, progressive, diffuse cystic lung disease predominantly affecting women of child bearing age. Recently treatment with sirolimus was shown to stabilize lung function decline and improve quality of life in patients with LAM. We treated three premenopausal women suffering from LAM manifesting as diffuse cystic lung disease, chylous effusions, and lymphangioleioyomas with sirolimus (1-3 mg a day; sirolimus trough levels 2.9-8.5 ng/ml). All three patients had a remarkable response to sirolimus, with resolution of effusions, improvement in lung function and shrinking of abdominal lymphangioleiomyomas. Our case series further complements the literature in that sirolimus is a safe and effective treatment for LAM and its lymphatic manifestations.

[Unusually late debut of lymphangioleiomyomatosis]

The rare, severe lung disease lymphangioleiomyomatosis (LAM) usually presents with dyspnoea on exertion, cough and expectoration in females in the third decade and is worsened by pregnancy or hormone therapy. Lung transplant is often needed within ten years since no specific treatment is available. The patient in this case report was a mother of two, who had never received hormone therapy. Once, when she was 47-years-old, she had had a period of dyspnoea and pleural empyema and no diagnosis was made, but being 75-years-old she was admitted with moderate dyspnoea on exertion, and high resolution CT showed cysts of the lungs classical for LAM.

Lymphatic manifestations of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a slowly progressive, low grade, metastasizing neoplasm, associated with cellular invasion and cystic destruction of the pulmonary parenchyma. Although the source of LAM cells that infiltrate the lung is unknown, available evidence indicates that the disease spreads primarily through lymphatic channels, often involving abdominal, axial, and retroperitoneal nodes, suggestive of an origin in the pelvis. LAM cells harbor mutations in tuberous sclerosis genes and produce lymphangiogenic growth factors, which facilitate access to and movement through the lymphatic system and likely play an important role in destructive tissue remodeling in the lung. Lymphatic manifestations of LAM include thoracic duct wall invasion, lymphangioleiomyoma formation, chylous fluid collections in the peritoneal, pleural, and pericardial spaces, chyloptysis, chylocolporrheal chylometrorrhea, chyle leak from the umbilicus, chylous pulmonary congestion, and lower extremity lymphedema. LAM lesions express lymphangiogenic growth factors VEGF-C and VEGF-D; growth factor receptors, VEGFR-2 and VEGFR-3; and markers LYVE-1 and podoplanin, and are laced with chaotic lymphatic channels. Serum VEGF-D is elevated in 70% of patients with LAM and is a clinically useful diagnostic and prognostic biomarker. Molecular targeted therapy with sirolimus stabilizes lung function, is anti-lymphangiogenic, and is highly effective for the lymphatic and chylous complications of LAM. Future trials in patients with LAM who have lymphatic manifestations or elevated serum VEGF-D will likely focus on the VEGF-C/VEGF-D/VEGFR-3 axis.

Clinical course and characterisation of lymphangioleiomyomatosis in a Brazilian reference centre

BACKGROUND AND OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare disease that promotes pulmonary cystic destruction and impairs pulmonary function. We aim to describe features and clinical course of LAM patients from Brazil.

METHODS

We described the clinical and functional features, performance in six minute walk test (6MWT), management details, survival and clinical course of 84 LAM patients followed in a Brazilian reference centre.

RESULTS

All subjects were women, the average age at onset of symptoms was 38 years, and the average at diagnosis was 42 years. The major symptoms during the course of the disease were dyspnoea and pneumothorax. The patients experienced impaired quality of life, with worse scores in the physical and emotional domains. The most common abnormalities in pulmonary function tests were an obstructive pattern and reduced diffusion capacity, whereas a quarter of the patients had normal spirometric results. In the 6MWT, although patients had preserved exercise capacity, more than half of the patients had significant desaturation. Hormonal blockage and doxycycline were the most common treatment modalities employed in our patients. The survival probability from diagnosis was 90% at 5 years, whereas the mean annual rate of decline in FEV1 was 60 ± 78 mL.

CONCLUSIONS

Clinical and functional features of the LAM patients from our centre are similar to those from other countries. Our sample showed preserved exercise capacity, with desaturation in the 6MWT, and impaired quality of life. Survival was similar, whereas the annual rate of decline of FEV1 was slightly lower than in recent studies.

[Current understanding and perspectives of lymphangioleiomyomatosis]

Lymphangioleiomyomatosis (LAM) is a slowly progressive neoplastic disease characterized with proliferation of abnormal smooth muscle-like cells (LAM cells) in the lungs and along axial lymphatics. Proliferation of LAM cells are considered to be driven by dysregulated mTORC1 signaling, that is caused by mutations in either the TSC1 or TSC2 gene in LAM cells. The MILES trial has successfully demonstrated that sirolimus, a mTORC1 inhibitor, can stabilize pulmonary function in LAM, but its effect disappears once sirolimus is discontinued. Limited ability of sirolimus may be due to concomitant activation of autophagy in LAM cells when mTORC1 activity is suppressed by sirolimus. Recently animal models for LAM have been independently established by several groups, which may provide a platform for developing drugs interfering various steps in disease progression.

A rare case of lymphangiomyomatosis treated with leuprolide acetate: five-years follow-up

Lymphangiomyomatosis (LAM) is a rare and systemic disease that is characterized by the abnormal proliferation of smooth muscle-like cells in the lungs and along the axial lymphatic system. The authors herein present a rare case of LAM that was treated with long-term use of leuprolide acetate, a gonadotropin-releasing hormone analogue (GnRHa).

[Pneumocystosis in a patient with lymphangioleiomyomatosis]

A 47-year-old, non-smoking woman was admitted to the National Tuberculosis and Lung Diseases Research Institute for diagnosis of progressive exertional dyspnoea and numerous small thin-walled, air-filled cysts equally distributed throughout both lungs revealed in HRCT (high resolution computed tomography) examination. Histological assessment of specimens obtained by open lung biopsy revealed proliferation of immature smooth muscle, showing the expression of the antigen HMB45. On this basis, diagnosis of lymphangioleiomyomatosis was established. The disease caused essential ventilation damage of the lungs (FEV1 1.34 L; 39.71% pred, VC 4.02 L; 94.96% pred, FEV1/ /VC 0.33-4 1.81% pred, DLCO 3.65 mmol/min/Kpa 38.35% pred).During the observation, despite the lack of immunological disorders, the patient developed Pneumocystis jiroveci pneumonia (PCP) that was treated with trimethoprimsulfamethoxazole. Lymphangioleiomyomatosis is a rare disease which results from a defect of TSC genes. The disease is not related to immunological defects or disorders. However, the considerable cystic destruction of the lungs can predispose the patient to opportunistic infections such as the one in the presented case.

[Treatment of pulmonary and retroperitoneal lymphangioleiomyomatosis with rapamycin: a case presentation and literature review]

To improve the diagnosis and treatment of pulmonary lymphangiomyomatosis, clinical data for the first successfully treated case of pulmonary and retroperitoneal lymphangiomyomatosis in our hospital has been comprehensively analyzed, and the relevant literature has been reviewed. A 45-year-old Han Chinese woman initially presented six months ago with increasing shortness of breath on exertion and was admitted to our hospital after four days of chest pain. Admission examination revealed chylothorax, interstitial lung disease, and enlarged retroperitoneal lymph nodes. The patient was finally diagnosed with pulmonary and retroperitoneal lymphangiomyomatosis based on laparotomy examination and biopsy of the retroperitoneal lymph nodes. After six months of rapamycin treatment, the symptoms - lung function, arterial blood gas, and imaging of the patient- were improved significantly. Pulmonary lymphangiomyomatosis clinically manifests as progressive dyspnea, recurrent pneumothorax, and chylothorax, and can be diagnosed by its characteristic features in high-resolution computed tomographic images or pathological examination. The successful treatment of pulmonary lymphangiomyomatosis with rapamycin brings new hope to those afflicted with this disease.

Real-time monitoring of tumorigenesis, dissemination, & drug response in a preclinical model of lymphangioleiomyomatosis/tuberous sclerosis complex

Background

TSC2-deficient cells can proliferate in the lungs, kidneys, and other organs causing devastating progressive multisystem disorders such as lymphangioleiomyomatosis (LAM) and tuberous sclerosis complex (TSC). Preclinical models utilizing LAM patient-derived cells have been difficult to establish. We developed a novel animal model system to study the molecular mechanisms of TSC/LAM pathogenesis and tumorigenesis and provide a platform for drug testing.

Methods and Findings

TSC2-deficient human cells, derived from the angiomyolipoma of a LAM patient, were engineered to co-express both sodium-iodide symporter (NIS) and green fluorescent protein (GFP). Cells were inoculated intraparenchymally, intravenously, or intratracheally into athymic NCr nu/nu mice and cells were tracked and quantified using single photon emission computed tomography (SPECT) and computed tomography (CT). Surprisingly, TSC2-deficient cells administered intratracheally resulted in rapid dissemination to lymph node basins throughout the body, and histopathological changes in the lung consistent with LAM. Estrogen was found to be permissive for tumor growth and dissemination. Rapamycin inhibited tumor growth, but tumors regrew after the drug treatment was withdrawn.

Conclusions

We generated homogeneous NIS/GFP co-expressing TSC2-deficient, patient-derived cells that can proliferate and migrate in vivo after intratracheal instillation. Although the animal model we describe has some limitations, we demonstrate that systemic tumors formed from TSC2-deficient cells can be monitored and quantified noninvasively over time using SPECT/CT, thus providing a much needed model system for in vivo drug testing and mechanistic studies of TSC2-deficient cells and their related clinical syndromes.

Chyloperitoneum, chylothorax and lower extremity lymphedema in woman with sporadic lymphangioleiomyomatosis successfully treated with sirolimus: a case report

Lymphangioleiomyomatosis (LAM) is a rare disease characterized by diffuse thin-walled cysts throughout the lungs on computed tomography and diffuse proliferation of abnormal smooth muscle-like cells (LAM cells) on lung biopsy. LAM affects women almost exclusively, predominantly in their reproductive age. The most typical presenting symptoms include dyspnea, spontaneous pneumothorax, cough and chylothorax. Abdominal findings represent less common initial manifestations of the disease and may pose diagnostic difficulties. The treatment of LAM has not been fully established. Recent studies report effectiveness of sirolimus in LAM patients. We report the case of a 45-year-old woman with sporadic LAM, successfully treated with sirolimus, in whom the first manifestation of the disease was chyloperitoneum and after three and nine years, respectively, lymphedema of the left lower extremity and right sided chylothorax occurred.

Successful pregnancy complicated by persistent pneumothorax in a patient with lymphangioleiomyomatosis (LAM) on sirolimus

We report a successful pregnancy in a patient with longstanding LAM on treatment with sirolimus. During temporary discontinuation fo sirolimus in early pregnancy, lung function declined but recovered after resumption of sirolimus. Pregnancy was complicated by a persistent pneumothorax which was treated surgically postnatally. The child has had a normal development despite exposure to low dose sirolimus intermittently during early embryonal and mid-fetal life.

Efficacy and safety of sirolimus in lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a progressive, cystic lung disease in women; it is associated with inappropriate activation of mammalian target of rapamycin (mTOR) signaling, which regulates cellular growth and lymphangiogenesis. Sirolimus (also called rapamycin) inhibits mTOR and has shown promise in phase 1-2 trials involving patients with LAM.

METHODS

We conducted a two-stage trial of sirolimus involving 89 patients with LAM who had moderate lung impairment--a 12-month randomized, double-blind comparison of sirolimus with placebo, followed by a 12-month observation period. The primary end point was the difference between the groups in the rate of change (slope) in forced expiratory volume in 1 second (FEV(1)).

RESULTS

During the treatment period, the FEV(1) slope was -12±2 ml per month in the placebo group (43 patients) and 1±2 ml per month in the sirolimus group (46 patients) (P<0.001). The absolute between-group difference in the mean change in FEV(1) during the treatment period was 153 ml, or approximately 11% of the mean FEV(1) at enrollment. As compared with the placebo group, the sirolimus group had improvement from baseline to 12 months in measures of forced vital capacity, functional residual capacity, serum vascular endothelial growth factor D (VEGF-D), and quality of life and functional performance. There was no significant between-group difference in this interval in the change in 6-minute walk distance or diffusing capacity of the lung for carbon monoxide. After discontinuation of sirolimus, the decline in lung function resumed in the sirolimus group and paralleled that in the placebo group. Adverse events were more common with sirolimus, but the frequency of serious adverse events did not differ significantly between the groups.

CONCLUSIONS

In patients with LAM, sirolimus stabilized lung function, reduced serum VEGF-D levels, and was associated with a reduction in symptoms and improvement in quality of life. Therapy with sirolimus may be useful in selected patients with LAM. (Funded by the National Institutes of Health and others; MILES ClinicalTrials.gov number, NCT00414648.).

Clinical and histopathological alterations of lymphangioleiomyomatosis in 14 Chinese patients

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare disease that predominantly affects young females. It is considered as an "orphan" life-threatening disease of unknown etiology, with uncertain clinical prognosis, and no effective treatment. LAM can arise sporadically or in association with tuberous sclerosis complex (TSC), an autosomal inherited syndrome characterized by hamartoma-like tumor growth and pathologic features that are distinct from manifestations of pulmonary LAM. The clinical course of LAM is characterized by progressive dyspnea on exertion, recurrent pneumothorax, and chylous fluid collections.

METHODS

Fourteen cases of LAM from Zhongshan Hospital, Fudan University are reviewed, twelve were confirmed by lung biopsy, one by retroperitoneal lymphangioleiomyoma resection, and one by autopsy.

RESULTS

All 14 patients were women, aged 18 to 69 years (mean 43.3 years, median 46.5 years). Haemoptysis (57.1%) and chylothorax (35.7%) were more frequent than those described in previous case series. Extrapulmonary findings such as renal angiomyolipoma (AML), enlarged abdominal lymph nodes, liver AML and retroperitoneal lymphangioleiomyoma were seen in 21.4%, 14.3%, 7.14% and 7.14% in 14 cases respectively, which is remarkably lower than in the previously reported. Abnormal smooth muscle cells (LAM cells) were found to line the airways, bronchioles, lymphatics and blood vessels leading to airflow obstruction and replacement of the lung parenchyma by cysts. There were some surprises in the autopsy case as several LAM cell emboli were found in the veins of mediastinum lymph nodes; LAM cells were found to be disseminated in soft tissues adjacent to the ilium.

CONCLUSIONS

Women with unexplained recurrent pneumothorax, tuberous sclerosis, or a diagnosis of primary spontaneous pneumothorax or emphysema in the setting of limited or absent tobacco use should undergo high-resolution computed tomography (HRCT) scan screening for LAM. Routine abdominal and pelvic imaging examinations should be performed to detect extrapulmonary involvement. The autopsy studies histologically suggested that LAM could be a multisystemic disease and LAM cells might possess metastatic potential.

Malignant epithelioid angiomyolipoma in the kidney and liver of a patient with pulmonary lymphangioleiomyomatosis: lack of response to sirolimus

A 26-year-old woman with lymphangioleiomyomatosis (LAM) was hospitalized for the surgical excision of a giant abdominal tumor of right kidney origin. The pathological diagnosis of the tumor was conventional angiomyolipoma (AML). After 8 months, 2 liver tumors appeared and grew rapidly. The tumors were resected, and the pathological finding of these tumors was epithelioid AML. Thereafter, metastatic multiple lung tumors appeared, and there was local recurrence of the liver tumors. Sirolimus, an mTOR protein inhibitor, was used to treat epithelioid AML. However, the drug did not inhibit the rapid growth of the tumor at all. This finding suggests that sirolimus might not be effective against epithelioid AML, and in such cases, complete surgical resection should be the treatment of choice.

Pulmonary lymphangioleiomyomatosis (LAM): progress and current challenges

Lymphangioleiomyomatosis (LAM), a rare lung disease, is characterized by the progressive proliferation, migration, and differentiation of smooth muscle (SM)-like LAM cells, which lead to the cystic destruction of the lung parenchyma, obstruction of airways and lymphatics, and loss of pulmonary function. LAM is a disease predominantly affecting women and is exacerbated by pregnancy; only a lung transplant can save the life of a patient. It has been discovered that in LAM, somatic or genetic mutations of tumor suppressor genes tuberous sclerosis complex 1 (TSC1) or TSC2 occur and the TSC1/TSC2 protein complex functions as a negative regulator of the mTOR/S6K1 signaling pathway. These two pivotal observations paved the way for the first rapamycin clinical trial for LAM. The recent discoveries that TSC1/TSC2 complex functions as an integrator of signaling networks regulated by growth factors, insulin, nutrients, and energy heightened the interest regarding this rare disease because the elucidation of disease-relevant mechanisms of LAM will promote a better understanding of other metabolic diseases such as diabetes, cancer, and cardiovascular diseases. In this review, we will summarize the progress made in our understanding of TSC1/TSC2 cellular signaling and the molecular mechanisms of LAM; we will also highlight some of the lesser explored directions and challenges in LAM research.

Rapid growth and regression of intracranial meningiomas in lymphangioleiomyomatosis: case report

BACKGROUND

Lymphangioleiomyomatosis is a progressive interstitial lung disease that affects young women. It has been suggested that estrogens play a role in its evolution, and progesterone therapy is often provided in these cases.

CASE DESCRIPTION

We present a case of a postmenopausal woman with LAM treated with progesterone; subsequently, rapid growth of multiple intracranial meningiomas was observed. One prominent lesion was excised, and 3 other lesions regressed spontaneously over 2 years.

CONCLUSIONS

This is a rare case of a non-pregnancy-related regression of meningiomas in a woman affected by LAM. The significance of this association and the hormonal treatment of the disease are discussed.