Clinical features, epidemiology, and therapy of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, characterized by proliferation of abnormal smooth muscle-like LAM cells, leading to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics (eg, lymphangioleiomyomas), and renal angiomyolipomas. LAM is caused by mutations of the TSC1 or TSC2 genes, which encode, respectively, hamartin and tuberin, two proteins with a major role in control of the mammalian target of rapamycin (mTOR) signaling pathway. LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal-dominant syndrome characterized by widespread hamartomatous lesions. LAM may present with progressive dyspnea, recurrent pneumothorax, or chylothorax. Pulmonary function tests show reduced flow rates (forced expiratory volume in the first second) and diffusion capacity. Exercise testing may reveal gas exchange abnormalities, ventilatory limitation, and hypoxemia. The severity and progression of disease may be assessed by lung histology scores, quantification of computed tomography, pulmonary function testing, 6-minute walk tests, cardiopulmonary exercise testing, and measurement of serum vascular endothelial growth factor D levels. Sirolimus and everolimus, two mTOR inhibitors, are effective in stabilizing lung function and reducing the size of chylous effusions, lymphangioleiomyo-mas, and angiomyolipomas. However, inhibition of mTOR complex 1 increases autophagy, possibly enhancing LAM cell survival. Inhibition of autophagy with hydroxychloroquine, in combination with sirolimus, has been proposed as a possible treatment for LAM. Deficiency of tuberin results in increased RhoA GTPase activity and cell survival, an effect that is mediated through mTOR complex 2 signaling. Because sirolimus and everolimus only affect the activity of mTOR complex 1, therapies targeting RhoA GTPases with simvastatin, which inhibits Rho GTPases and promotes apoptosis, are being investigated. As in the case of cancer, LAM may be best treated with multiple drugs targeting signaling pathways considered important in the pathogenesis of disease.

The next breakthrough in LAM clinical trials may be their design: challenges in design and execution of future LAM clinical trials

The past decade has resulted in stunning progress in the pathogenesis and therapy of lymphangioleiomyomatosis (LAM), culminating in the pivotal 'MILES' trial, the first-ever randomized, placebo-controlled trial in LAM, demonstrating the efficacy of sirolimus in 2011. Here, we review clinical progress since 2011, focusing on new therapeutic and observational trials. These trials include the second randomized, placebo-controlled trial, a 2-year study of doxycycline effectiveness in LAM. Other clinical studies have addressed lower-dose sirolimus and treatment of pulmonary hypertension. An improved understanding of LAM pathogenesis is essential to future therapeutic breakthroughs. Critical questions that remain to be addressed include the role of estrogen and lymphangiogenesis in LAM pathogenesis and therapy, mechanisms of cystic lung destruction, the role of autophagy and pro-survival pathways in LAM cell survival. Ultimately, achieving future 'breakthroughs' in LAM will require continued rigorous basic and preclinical investigation, innovative clinical trial design and robust biomarkers.

Rapamycin-resistant poly (ADP-ribose) polymerase-1 overexpression is a potential therapeutic target in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a female-predominant cystic lung disease that can lead to respiratory failure. LAM cells typically have inactivating tuberous sclerosis complex 2 (TSC2) mutations and mammalian target of rapamycin (mTOR) complex (mTORC) 1 activation. Clinical response to the mTORC1 inhibitors has been limited, prompting a search for additional therapy for LAM. In this study, we investigated the impact of TSC2 on the expression of poly (ADP-ribose) polymerase (PARP)-1 that initiates the DNA repair pathway, and tested the efficacy of PARP1 inhibitors in the survival of TSC2-deficient (TSC2(-)) cells. We analyzed publicly available expression arrays of TSC2(-) cells and validated the findings using real-time RT-PCR, immunoblotting, and immunohistochemistry. We examined the impact of rapamycin and Torin 1 on PARP1 expression. We also tested the effect of PARP1 inhibitors, 8-hydroxy-2-methylquinazoline-4-one and 3,4-dihydro-5[4-(1-piperindinyl)butoxy]-1(2H)-isoquinoline, on the survival of TSC2(-) cells. We identified the up-regulation of PARP1 in TSC2(-) cells relative to cells in which wild-type TSC2 has been reintroduced (TSC2-addback [TSC2(+)] cells). The transcript levels of PARP1 in TSC2(-) cells were not affected by rapamycin. PARP1 levels were increased in TSC2(-) cells, xenograft tumors of rat-derived TSC2(-) cells, renal cystadenomas from Tsc2(+/-) mice, and human LAM nodules. RNA interference of mTOR failed to reduce PARP1 levels. Proliferation and survival of TSC2(-) cells was reduced in response to PARP1 inhibitor treatment, more so than TSC2(+) cells. TSC2(-) cells exhibit higher levels of PARP1 relative to TSC2(+) cells in an mTOR-insensitive manner. PARP1 inhibitors selectively suppress the growth and induce apoptosis of TSC2(-) cells from patients with LAM. Targeting PARP1 may be beneficial in the treatment of LAM and other neoplasm with mTORC1 activation.

Pharmacological inhibition of Polo-like kinase 1 (PLK1) by BI-2536 decreases the viability and survival of hamartin and tuberin deficient cells via induction of apoptosis and attenuation of autophagy

The mechanistic target of rapamycin complex 1 (mTORC1) increases translation, cell size and angiogenesis, and inhibits autophagy. mTORC1 is negatively regulated by hamartin and tuberin, the protein products of the tumor suppressors TSC1 and TSC2 that are mutated in Tuberous Sclerosis Complex (TSC) and sporadic Lymphangioleiomyomatosis (LAM). Hamartin interacts with the centrosomal and mitotic kinase polo-like kinase 1 (PLK1). Hamartin and tuberin deficient cells have abnormalities in centrosome duplication, mitotic progression, and cytokinesis, suggesting that the hamartin/tuberin heterodimer and mTORC1 signaling are involved in centrosome biology and mitosis. Here we report that PLK1 protein levels are increased in hamartin and tuberin deficient cells and LAM patient-derived specimens, and that this increase is rapamycin-sensitive. Pharmacological inhibition of PLK1 by the small-molecule inhibitor BI-2536 significantly decreased the viability and clonogenic survival of hamartin and tuberin deficient cells, which was associated with increased apoptosis. BI-2536 increased p62, LC3B-I and GFP-LC3 punctae, and inhibited HBSS-induced degradation of p62, suggesting that PLK1 inhibition attenuates autophagy. Finally, PLK1 inhibition repressed the expression and protein levels of key autophagy genes and proteins and the protein levels of Bcl(-)2 family members, suggesting that PLK1 regulates both autophagic and apoptotic responses. Taken together, our data point toward a previously unrecognized role of PLK1 on the survival of cells with mTORC1 hyperactivation, and the potential use of PLK1 inhibitors as novel therapeutics for tumors with dysregulated mTORC1 signaling, including TSC and LAM.

Extrapulmonary lymphangioleiomyomatosis mimicking lymphoma metastatic to uterus

Lymphangioleiomyomatosis is a very rare disease that primarily affects the lungs. The atypical smooth muscle cells in these tumors stain both with smooth muscle markers and melanocytic markers characteristically like their counterparts in other members of the PEComa family. Extrapulmonary lymphangioleiomyomatosis, especially without pulmonary involvement, is extremely rare. The clinical importance of lymphangioleiomyomatosis lies in the fact that it may mimic other malignant diseases, such as lymphoma or sarcoma. Here, we report a case of extrapulmonary lymphangioleiomyomatosis without involvement of the lungs, in a patient pre-diagnosed as having lymphoma metastasized to the uterus or uterine sarcoma.

Should mammalian target of rapamycin inhibitors be stopped in women with lymphangioleiomyomatosis awaiting lung transplantation?

Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease characterized by proliferation of smooth muscle like cells (LAM cells) that have mutations in the tuberous sclerosis gene (TSC2), leading to the activation of the mammalian target of rapamycin (mTOR). Rapamycin, an inhibitor of the mTOR pathway, has been shown in a landmark clinical trial to halt the decline in lung function, as long as it is used continuously. Women with severe pulmonary LAM still progress to require lung transplantation. The use of inhibitors of the mTOR pathway immediately after transplant has been linked to bronchial anastomotic dehiscence, a potentially fatal complication of lung transplantation. Currently, it is recommended that women with LAM stop taking rapamycin once listed for lung transplant, which could potentially lead to faster lung function decline while awaiting organ transplantation. Here we review the existing evidence and discuss potential recommendations for the management of the inhibitors of the mTOR pathway while awaiting lung transplantation.

Lymphangioleiomyomatosis: differential diagnosis and optimal management

Lymphangioleiomyomatosis (LAM) is an uncommon disease presented as diffuse thin-walled cystic changes in the lung. The main differential diagnoses include pulmonary Langerhans’ histiocytosis (PLCH), Birt-Hogg-Dubé syndrome (BHD), lymphoid interstitial pneumonia (LIP), and amyloidosis. A combination of clinical, radiological, and pathological approaches as well as genetic testing will clarify the diagnosis in most cases. LAM is a disease almost exclusively in women. Dyspnea, pneumothorax, and hemoptysis are common presentations in LAM patients. LAM is also a lymphatic disorder affecting lymphatic vessels and lymph nodes. Chylothorax, chylous ascites, and lymphangiomyomas are frequently seen. LAM can present sporadically as a single entity or as part of tuberous sclerosis complex (TSC). Angiomyolipoma (AML) is a characteristic extra-pulmonary lesion, either found in association with sporadic or TSC-related LAM. High-risk populations should be screened for LAM, including adult women with TSC and female patients with spontaneous pneumothorax, AMLs in the kidney, and diffuse cystic lung diseases. Definitive diagnosis of LAM is based on a high level of clinical suspicion on presentation supported by pathological findings or by a distinct feature, such as a history of TSC, AMLs in the kidney, chylothorax, or chylous ascites. Vascular endothelial growth factor-D (VEGF-D) in serum is a noninvasive and reliable diagnostic biomarker. In experienced centers, trans-bronchial lung biopsy (TBLB) provides a convenient and safe way to obtain lung specimens for diagnostic purposes. An effective treatment for LAM is now available, namely using a mechanistic target of rapamycin (mTOR) inhibitor such as sirolimus. Efficacy of sirolimus has been confirmed in clinical trials. Research in other molecular-targeted therapies is under investigation. A previously little-known rare disease with no cure is now better understood with regards to its pathogenesis, diagnosis, and management. In this review, current knowledge in diagnosis and differential diagnosis of LAM will be discussed, followed by the discussion of therapy with mTOR inhibitors.

Successful management of bilateral refractory chylothorax after double lung transplantation for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease that leads to airways and lymphatic channels obstruction due to abnormal smooth muscle proliferation. It presents with dyspnea, pneumothorax or chylothorax. Lung transplantation (LT) has emerged as a valuable therapeutic option with limited reports. We report a case of LAM that underwent double LT and complicated by refractory bilateral chylothorax which was managed successfully by povidone-iodine pleurodesis and the addition of sirolimus to the post-transplantation immunosuppressive therapy. The patient has no recurrence with 24 months follow-up.

TSC2 epigenetic defect in primary LAM cells. Evidence of an anchorage-independent survival

Tuberous sclerosis complex (TSC) is caused by mutations in TSC1 or TSC2 genes. Lymphangioleiomyomatosis (LAM) can be sporadic or associated with TSC and is characterized by widespread pulmonary proliferation of abnormal α-smooth muscle (ASM)-like cells. We investigated the features of ASM cells isolated from chylous thorax of a patient affected by LAM associated with TSC, named LAM/TSC cells, bearing a germline TSC2 mutation and an epigenetic defect causing the absence of tuberin. Proliferation of LAM/TSC cells is epidermal growth factor (EGF)-dependent and blockade of EGF receptor causes cell death as we previously showed in cells lacking tuberin. LAM/TSC cells spontaneously detach probably for the inactivation of the focal adhesion kinase (FAK)/Akt/mTOR pathway and display the ability to survive independently from adhesion. Non-adherent LAM/TSC cells show an extremely low proliferation rate consistent with tumour stem-cell characteristics. Moreover, LAM/TSC cells bear characteristics of stemness and secrete high amount of interleukin (IL)-6 and IL-8. Anti-EGF receptor antibodies and rapamycin affect proliferation and viability of non-adherent cells. In conclusion, the understanding of LAM/TSC cell features is important in the assessment of cell invasiveness in LAM and TSC and should provide a useful model to test therapeutic approaches aimed at controlling their migratory ability.

Everolimus in the treatment of subependymal giant cell astrocytomas, angiomyolipomas, and pulmonary and skin lesions associated with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by inactivating mutations in either the TSC1 or TSC2 genes. It is characterized by the development of multiple, benign tumors in several organs throughout the body. Lesions occur in the brain, kidneys, heart, liver, lungs, and skin and result in seizures and epilepsy, mental retardation, autism, and renal and pulmonary organ system dysfunction, as well as other complications. Elucidation of the molecular pathways and etiological factors responsible for causing TSC has led to a paradigm shift in the management and treatment of the disease. TSC1 or TSC2 mutations lead to constitutive upregulation of the mammalian target of rapamycin pathway, which affects many cellular processes involved in tumor growth. By targeting mammalian target of rapamycin with everolimus, an orally active rapamycin derivative, clinically meaningful and statistically significant reductions in tumor burden have been achieved for the main brain (subependymal giant cell astrocytoma) and renal manifestations (angiomyolipoma) associated with TSC. This review provides an overview of TSC, everolimus, and the clinical trials that led to its approval for the treatment of TSC-associated subependymal giant cell astrocytoma and renal angiomyolipoma.

VATS therapy of chylothorax caused by leiomyomatosis complicated with tuberous sclerosis complex

Lymphangioleiomyomatosis with tuberous sclerosis complex is a rare disease. One of the most frequent complications of lymphangioleiomyomatosis is pleural effusion (chylothorax) wich can be treated with the use of VATS. Authors report a case of pulmonary lymphangioleiomyomatosis in a 56-year-old female patient with tuberous sclerosis complex with an 8-week history of recurrent chylothorax, dyspnea and debilitating weakness. By CT scan a flat tissue proliferation was seen in the site of the thoracic duct and it was supposed to be the reason for the pleural effusion. A VATS resection of this laesion and ligation of the thoracic duct was performed successfully. Chylothorax is often associated with pulmonary lymphangioleiomyomatosis. Lymphangioleiomyomatosis combined with tuberous sclerosis complex is extremely rare. In case of chylothorax VATS treatment is successful and may be the first choice.

Lymphatic endothelial differentiation in pulmonary lymphangioleiomyomatosis cells

Pulmonary lymphangioleiomyomatosis (LAM) is a rare, low-grade neoplasm affecting almost exclusively women of childbearing age. LAM belongs to the family of perivascular epithelioid cell tumors, characterized by spindle and epithelioid cells with smooth muscle and melanocytic differentiation. LAM cells infiltrate the lungs, producing multiple, bilateral lesions rich in lymphatic channels and forming cysts, leading to respiratory insufficiency. Here we used antibodies against four lymphatic endothelial markers-podoplanin (detected by D2-40), prospero homeobox 1 (PROX1), vascular endothelial growth factor receptor 3 (VEGFR-3), and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1)-to determine whether LAM cells show lymphatic differentiation. Twelve of 12 diagnostic biopsy specimens (early-stage LAM) and 19 of 19 explants (late-stage LAM) showed immunopositivity for D2-40 in most neoplastic cells. PROX1, VEGFR-3, and LYVE1 immunoreactivity varied from scarce in the early stage to abundant in the late stage. Lymphatic endothelial, smooth muscle, and melanocytic markers were partially co-localized. These findings indicate that lymphatic endothelial differentiation is a feature of LAM and provide evidence of a previously unidentified third lineage of differentiation in this neoplasm. This study has implications for the histological diagnosis of LAM, the origin of the neoplastic cells, and potential future treatment with drugs targeting lymphangiogenesis.

Optimizing treatments for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease predominantly affecting premenopausal women, is associated with cystic lung destruction and lymphatic and kidney tumors. LAM results from the proliferation of a neoplastic cell that has mutations in the tuberous sclerosis complex 1 or 2 genes, leading to activation of a critical regulatory protein, mammalian target of rapamycin. In this report, we discuss the molecular mechanisms regulating LAM cell growth and report the results of therapeutic trials employing new targeted agents. At present, inhibitors of mammalian target of rapamycin such as sirolimus appear to be the most promising therapeutic agents, although drug toxicity and development of resistance are potential problems. As the pathogenesis of LAM is being further recognized, other therapeutic agents such as matrix metalloproteinase inhibitors, statins, interferon, VEGF inhibitors, chloroquine analogs and cyclin-dependent kinase inhibitors, along with sirolimus or a combination of several of these agents, may offer the best hope for effective therapy.

Giant bilateral renal angiomyolipomas and lymphangioleiomyomatosis presenting after two successive pregnancies successfully treated with surgery and rapamycin

We report the case of a 25-year-old woman who presented with abdominal and flank pain with two successive pregnancies and was diagnosed of giant bilateral renal AMLs and pulmonary LAM associated with TSC in the post-partum of her second pregnancy. This case illustrates that in women with TSC rapid growth from renal AMLs and development of LAM may occur with successive pregnancies. It also stresses the potential for preservation of renal function despite successive bilateral renal surgery of giant AMLs. Moreover, the treatment with a low-dose rapamycin may be an option for LAM treatment. Finally, a low-dose rapamycin may be considered as an adjuvant treatment together to kidney-sparing conservative surgery for renal AMLs.

Prevalence of uterine leiomyomas in lymphangioleiomyomatosis

OBJECTIVE

To determine the frequency of uterine leiomyomas and hysterectomy in patients with lymphangioleiomyomatosis (LAM), a disease characterized by proliferation of abnormal-appearing smooth muscle-like cells.

DESIGN

Retrospective study.

SETTING

Natural history study at the National Institutes of Health.

PATIENT(S)

456 patients with sporadic LAM and LAM associated with tuberous sclerosis complex (LAM/TSC).

INTERVENTION(S)

Review of records and pelvic computed axial tomography scans.

MAIN OUTCOME MEASURE(S)

Prevalence of uterine leiomyomas and hysterectomy.

RESULT(S)

A total of 174 women had uterine leiomyomas (38%). One hundred eighteen were diagnosed by computed tomographic scan and 56 were diagnosed by hysterectomy. Among 323 patients who did not have hysterectomy, 105 of 270 patients (39%) with sporadic LAM and 13 of 53 (25%) with LAM/TSC had uterine leiomyomas. Hysterectomy was performed in 108 of 378 subjects with sporadic LAM and 25 of 78 with LAM/TSC. Fifty-six patients were found to have uterine fibroids on hysterectomy. The most common indications for hysterectomy were uterine leiomyoma, LAM, and endometriosis.

CONCLUSION(S)

Uterine leiomyomas are not more common in LAM than in the general population. However, in LAM, the frequency of hysterectomy is higher because of it having been recommended for treatment of LAM.

Clinically relevant imaging in tuberous sclerosis

Tuberous sclerosis (TS), also known as Bourneville disease or Bourneville–Pringle disease, is an autosomal dominant genetic disorder classically characterized by the presence of hamartomatous growths in multiple organs. TS and tuberous sclerosis complex (TSC) are different terms for the same genetic condition. Both terms describe clinical changes due to mutations involving either of the two genes named TSC1 and TSC2, which regulate cell growth. The diagnosis of TSC is established using diagnostic criteria based on clinical and imaging findings. Routine screening and surveillance of patients with TSC is needed to determine the presence and extent of organ involvement, especially the brain, kidneys, and lungs, and identify the development of associated complications. As the treatment is organ specific, imaging plays a crucial role in the management of patients with TSC.

Lymphangioleiomyomatosis: what do we know and what are we looking for?

Lymphangioleiomyomatosis (LAM) is a rare disease characterised by proliferation of abnormal smooth muscle-like cells (LAM cells) leading to progressive cystic destruction of the lung, lymphatic abnormalities and abdominal tumours. It affects predominantly females and can occur sporadically or in patients with tuberous sclerosis complex. This review describes the recent progress in our understanding of the molecular pathogenesis of the disease and LAM cell biology. It also summarises current therapeutic approaches and the most promising areas of research for future therapeutic strategies.

Phenotypic characterization of disseminated cells with TSC2 loss of heterozygosity in patients with lymphangioleiomyomatosis

RATIONALE

Lymphangioleiomyomatosis (LAM), occurring sporadically (S-LAM) or in patients with tuberous sclerosis complex (TSC), results from abnormal proliferation of LAM cells exhibiting mutations or loss of heterozygosity (LOH) of the TSC genes, TSC1 or TSC2.

OBJECTIVES

To identify molecular markers useful for isolating LAM cells from body fluids and determine the frequency of TSC1 or TSC2 LOH.

METHODS

Candidate cell surface markers were identified using gene microarray analysis of human TSC2⁻(/)⁻ cells. Cells from bronchoalveolar lavage fluid (BALF), urine, chylous effusions, and blood were sorted based on reactivity with antibodies against these proteins (e.g., CD9, CD44v6) and analyzed for LOH using TSC1- and TSC2-related microsatellite markers and single nucleotide polymorphisms in the TSC2 gene.

MEASUREMENTS AND MAIN RESULTS

CD44v6(+)CD9(+) cells from BALF, urine, and chyle showed TSC2 LOH in 80%, 69%, and 50% of patient samples, respectively. LAM cells with TSC2 LOH were detected in more than 90% of blood samples. LAM cells from different body fluids of the same patients showed, in most cases, identical LOH patterns, that is, loss of alleles at the same microsatellite loci. In a few patients with S-LAM, LAM cells from different body fluids differed in LOH patterns. No patients with S-LAM with TSC1 LOH were identified, suggesting that TSC2 abnormalities are responsible for the vast majority of S-LAM cases and that TSC1-disease may be subclinical.

CONCLUSIONS

Our data support a common genetic origin of LAM cells in most patients with S-LAM, consistent with a metastatic model. In some cases, however, there was evidence for genetic heterogeneity between LAM cells in different sites or within a site.

Tuberous sclerosis complex: neurological, renal and pulmonary manifestations

Tuberous sclerosis complex (TSC) is an important cause of epilepsy and autism, as well as renal and pulmonary disease in adults and children. Affected individuals are subject to hamartomas in various organ systems which result from constitutive activation of the protein kinase mTOR (mammalian target of rapamycin). The clinical course, prognosis and appropriate therapy for TSC patients are often different from that for individuals with epilepsy, renal tumors, or interstitial lung disease, from other causes. Additionally, TSC serves as a model for other conditions in which the mTOR pathways are also up-regulated. This article reviews the molecular pathophysiology and management of neurological, renal and pulmonary manifestations of the disorder. The use of mTOR inhibitors such as rapamycin and everolimus is discussed and recent clinical trials of these drugs in TSC are reviewed.

Multiple pneumothoraces during second and third trimesters as first presentation of lymphangioleiomyomatosis

A case of lymphangioleiomyomatosis presenting as multiple pneumothoraces during pregnancy is described below. Presentations, management and prognosis are discussed.