Rapamycin as a Therapy of Choice After Renal Transplantation in a Patient With Tuberous Sclerosis Complex

Tuberous Sclerosis Complex and the kidneys: what nephrologists need to know

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the development of hamartomas in the central nervous system, heart, skin, lungs, and kidneys and other manifestations including seizures, cortical tubers, radial migration lines, autism and cognitive disability. The disease is associated with pathogenic variants in the TSC1 or TSC2 genes, resulting in the hyperactivation of the mTOR pathway, a key regulator of cell growth and metabolism. Consequently, the hyperactivation of the mTOR pathway leads to abnormal tissue proliferation and the development of solid tumors. Kidney involvement in TSC is characterized by the development of cystic lesions, renal cell carcinoma and renal angiomyolipomas, which may progress and cause pain, bleeding, and loss of kidney function. Over the past years, there has been a notable shift in the therapeutic approach to TSC, particularly in addressing renal manifestations. mTOR inhibitors have emerged as the primary therapeutic option, whereas surgical interventions like nephrectomy and embolization being reserved primarily for complications unresponsive to clinical treatment, such as severe renal hemorrhage. This review focuses on the main clinical characteristics of TSC, the mechanisms underlying kidney involvement, the recent advances in therapy for kidney lesions, and the future perspectives.

Identification of an Electrogenic 2Cl-/H+ Exchanger, ClC5, as a Chloride-Secreting Transporter Candidate in Kidney Cyst Epithelium in Tuberous Sclerosis

Kidney cyst expansion in tuberous sclerosis complex (TSC) or polycystic kidney disease (PKD) requires active secretion of chloride (Cl-) into the cyst lumen. In PKD, Cl- secretion is primarily mediated via the cystic fibrosis transmembrane conductance regulator (CFTR) in principal cells. Kidney cystogenesis in TSC is predominantly composed of type A intercalated cells, which do not exhibit noticeable expression of CFTR. The identity of the Cl--secreting molecule(s) in TSC cyst epithelia remains speculative. RNA-sequencing analysis results were used to examine the expression of FOXi1, the chief regulator of acid base transporters in intercalated cells, along with localization of Cl- channel 5 (ClC5), in various models of TSC. Results from Tsc2+/- mice showed that the expansion of kidney cysts corresponded to the induction of Foxi1 and correlated with the appearance of ClC5 and H+-ATPase on the apical membrane of cyst epithelia. In various mouse models of TSC, Foxi1 was robustly induced in the kidney, and ClC5 and H+-ATPase were expressed on the apical membrane of cyst epithelia. Expression of ClC5 was also detected on the apical membrane of cyst epithelia in humans with TSC but was absent in humans with autosomal dominant PKD or in a mouse model of PKD. These results indicate that ClC5 is expressed on the apical membrane of cyst epithelia and is a likely candidate mediating Cl- secretion into the kidney cyst lumen in TSC.

Characterization and management of facial angiofibroma related to tuberous sclerosis complex in the United States: retrospective analysis of the natural history database

Background

Facial angiofibroma is the most predominant cutaneous manifestation of tuberous sclerosis complex (TSC), a rare autosomal dominant genetic disorder impacting the mechanistic target of rapamycin (mTOR). Facial angiofibroma can bleed spontaneously, impair eyesight, and cause aesthetic disfiguration causing psychological and social stress. To date, there is little or no evidence on the demographics, and other TSC features associated with facial angiofibroma or the use of mTOR inhibitor for the management of facial angiofibroma. This is a retrospective study of TSC Alliance’s Natural History Database aimed to characterize facial angiofibroma and to evaluate features associated with a higher risk of facial angiofibroma or the use of topical mTOR inhibitors for the management of facial angiofibroma. Data in the NHD was obtained from 18 clinical sites in the US since 2006.

Results

Of the 2240 patients, 2088 patients were enrolled in the US and data from 2057 patients were included in this analysis. The mean (median) age of overall TSC patients was 22.4 (19.0) years. A total of 69 patients were ≤ 5 years of age. Facial angiofibroma was noted in 1329 (64.6%) patients with TSC. Patients with facial angiofibroma were older on average (Mean: 25.9 [median, 23.0] vs. 16.0 [12.4 years] years, p < 0.0001). In patients with vs. without facial angiofibroma, TSC2 mutation (38.9% vs. 34.8%) was more common than TSC1 mutation (12.3% vs. 18.1%), and the incidence rate of most of the other TSC-related manifestations was significantly higher in patients with facial angiofibroma. Majority of patients had focal seizures (72.8% vs. 60.7%), followed by angiomyolipoma (63.7% vs. 21.8%) and renal cysts (59.4% vs. 33.5%). The age groups, 11–17 (odds ratio [OR], 2.53) and 18–45 years (5.98), TSC2 mutation (1.31), focal seizures (1.50), ADHD (1.47) angiomyolipoma (2.79), and renal cysts (2.63) were significantly associated with a higher risk of facial angiofibroma based on multivariate logistic regression. Abrasive or laser therapy was used by 17.1% and 2.6% patients, respectively. Topical mTOR inhibitor use was noted for 329 (24.8%) patients with facial angiofibroma. Overall systemic mTOR inhibitor use was observed in 399 (30.0%) patients for management of one or more TSC manifestations. Use of systemic mTOR inhibitor for facial angiofibroma was noted for 163 (12.3%) patients, among whom only 9 (0.7%) patients used exclusively for the management of facial angiofibroma. Of the patients with facial angiofibroma, 44.6% did not receive any treatment. Significantly higher use of topical mTOR inhibitor was associated with the 11–17 years age group (OR, 1.67), anxiety (1.57), angiomyolipoma (1.51), and renal cysts (1.33).

Conclusions

The presence of TSC2 mutations and most other TSC-related manifestations was significantly higher in patients with facial angiofibroma. About one-fourth of patients with facial angiofibroma used a topical mTOR inhibitor and use of systemic mTOR inhibitor for the management of facial angiofibroma or for the other manifestations was noted for 30.0%. About 44.6% of patients did not receive any treatment for the management of facial angiofibroma.

Kidney intercalated cells and the transcription factor FOXi1 drive cystogenesis in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is caused by mutations in TSC1 or TSC2 gene and affects multiple organs, including the kidney, where it presents with angiomyolipomata and cysts that can result in kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Current studies demonstrate that kidney cyst epithelia in TSC mouse models and in humans with TSC are composed of hyperproliferating intercalated cells, along with activation of H⁺-ATPase and carbonic anhydrase 2. Interfering with intercalated cell proliferation completely inhibited and inactivating carbonic anhydrase 2 significantly protected against cyst formation in TSC. Targeting the acid base and/or electrolyte transporters of intercalated cells may provide a therapeutic approach for the treatment of kidney cysts in TSC.

Tuberous sclerosis complex (TSC) is caused by mutations in either TSC1 or TSC2 genes and affects multiple organs, including kidney, lung, and brain. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomata) and cysts, which eventually leads to kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Here, we report that mice with principal cell-specific inactivation of Tsc1 develop numerous cortical cysts, which are overwhelmingly composed of hyperproliferating A-intercalated (A-IC) cells. RNA sequencing and confirmatory expression studies demonstrated robust expression of Forkhead Transcription Factor 1 (Foxi1) and its downstream targets, apical H⁺-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in cyst epithelia in Tsc1 knockout (KO) mice but not in Pkd1 mutant mice. In addition, the electrogenic 2Cl⁻/H⁺ exchanger (CLC-5) is significantly up-regulated and shows remarkable colocalization with H⁺-ATPase on the apical membrane of cyst epithelia in Tsc1 KO mice. Deletion of Foxi1, which is vital to intercalated cells viability and H⁺-ATPase expression, completely abrogated the cyst burden in Tsc1 KO mice, as indicated by MRI images and histological analysis in kidneys of Foxi1/Tsc1 double-knockout (dKO) mice. Deletion of CAII, which is critical to H⁺-ATPase activation, caused significant reduction in cyst burden and increased life expectancy in CAII/Tsc1 dKO mice vs. Tsc1 KO mice. We propose that intercalated cells and their acid/base/electrolyte transport machinery (H⁺-ATPase/CAII/CLC-5) are critical to cystogenesis, and their inhibition or inactivation is associated with significant protection against cyst generation and/or enlargement in TSC.

Topical rapamycin in the treatment of facial angiofibromas in tuberous sclerosis: a systematic review based on evidence

INTRODUCTION

facial angiofibromas of tuberous sclerosis are the most prevalent cutaneous manifestation, affecting 80% of patients, which cause facial lesions with negative psychosocial consequences. Newly, topical rapamycin has been established as an effective and safe therapy for this skin condition.

PURPOSE

to analyze the available scientific evidence about the effectiveness and safety of topical sirolimus in the treatment of facial angiofibromas in tuberous sclerosis.

METHODS

a literature search was conducted in PubMed and Cochrane. Effectiveness and safety were analyzed along with the main characteristics of each formulation in all included studies.

RESULTS

thirty studies were included involving a total of 508 patients, developed in the last 20 years. Four randomized clinical trial, 17 case series and 9 single case reports were founded. Multiple topical rapamycin concentrations (0.003-1%) and formulations (gel, ointment, solution) were found in literature. Rapamycin demonstrated its effectiveness in all studies included, except for 5 patients in a 1 b study. Rapamycin was shown to be safe for the treatment of FA.

CONCLUSIONS

Topical sirolimus can be considered an effective and safety option for the treatment of facial angiofibromas in tuberous sclerosis. However, further long-term studies need to establish an evidence-based therapeutic protocol.KEY MESSAGEUpdated review to date in topical rapamycin for facial angiofibromas, allowing support in therapeutic decisions.

Living Donor Preemptive Kidney Transplantation in Tuberous Sclerosis Complex Patient and the Role of Mammalian Target of Rapamycin Inhibitor: A Case Report

BACKGROUND

Kidney transplantation (KT) is the preferred treatment for end-stage kidney disease (ESKD), while preemptive (PE) living donor (LD) KT is associated with better survival, quality of life, and lower costs. Tuberous sclerosis complex (TSC) is a genetic multisystem disorder. Renal involvement (multiple bilateral angiomyolipoma [AMLs], cysts, renal cell carcinoma [RCC]) is related to significant morbidity, including ESKD and KT. Nephrectomy in TSC patients before KT is controversial. Affected kidneys carry a risk of hemorrhage or malignancy, while AMLs may be fat-poor and are often hardly distinguishable from RCC in magnetic resonance (MR)/computed tomography. On the other hand nephrectomy impedes PE KT. Mammalian target of rapamycin inhibitors (mTORi) have proved efficacy in many TSC complications, including AMLs, fat-poor AMLs, TSC-related RCC, and immunosuppressive (IS) treatment.

CASE REPORT

A 29-year-old female TSC patient was referred for evaluation to the TSC reference center. Her family history was negative for TSC. A clinical evaluation revealed multisystem TSC manifestation (skin, brain, lungs, kidneys). MR disclosed indeterminate fat-poor renal lesions, possibly AMLs, but RCC could not be excluded. A comparison with previous MR did not show any significant progression. Due to ESKD, the patient was qualified for PE LD (mother) KT. mTORi, sirolimus, was used in IS. Creatinine at discharge was 2.1 mg/dL. Sixteen months later, MR showed significant reduction in tumor size. Two years after KT, graft function remained stable (creatinine 1.98 mg/dL). No complications related to renal lesions occurred.

CONCLUSIONS

mTORi are the therapy of choice in TSC patients after KT, achieving IS effect and improvement in TSC manifestations while avoiding nephrectomy and management of patients with indeterminate renal lesions, especially in the case of PE KT.

Safety and Efficacy of the Sirolimus Gel for TSC Patients With Facial Skin Lesions in a Long-Term, Open-Label, Extension, Uncontrolled Clinical Trial

Introduction

Our previous clinical studies have demonstrated the short-term efficacy and safety of the sirolimus gel for patients with tuberous sclerosis complex (TSC). However, long-term clinical evidence is lacking. Our objective was to assess the safety and efficacy of long-term treatment with the sirolimus gel for the skin lesions of TSC patients.

Methods

We conducted a multicenter, open-label, uncontrolled clinical trial in 94 Japanese patients with TSC. Patients applied the 0.2% sirolimus gel on their face or head twice daily for > 52 weeks (maximum 136 weeks for safety). The safety endpoints were the rate of adverse event (AE)-caused discontinuation (primary endpoint) and the incidence of AEs. The efficacy endpoint was the response rate of angiofibromas, cephalic plaques, and hypomelanotic macules.

Results

Among 94 enrolled patients (mean age, 21 years; range 3–53 years), the rate of AE-caused discontinuation was 2.1% (2/94 patients). Although application site irritation and dry skin occurred relatively frequently, none of the drug-related AEs were serious; most of the drug-related AEs resolved rapidly. The major drug-related AEs (≥ 5% in incidence) were application site irritation (30.9%), dry skin (27.7%), acne (20.2%), eye irritation (8.5%), pruritus (8.5%), erythema (7.4%), dermatitis acneiform (6.4%), and dermatitis contact (5.3%). The response rates of angiofibromas, cephalic plaques, and hypomelanotic macules were 78.2% [95% confidence interval (CI) 68.0–86.3%], 66.7% (95% CI 51.1–80.0%), and 72.2% (95% CI 46.5–90.3%), respectively.

Conclusions

The gel was well tolerated for a long time by patients with TSC involving facial skin lesions and continued to be effective.

Trial Registration

ClinicalTrials.gov identifier: NCT02634931.

Tuberous sclerosis complex: new insights into clinical and therapeutic approach

Tuberous sclerosis complex (TSC) is a complex disease with many different clinical manifestations. Despite the common opinion that TSC is a rare condition, with a mean incidence of 1/6000 live births and a prevalence of 1/20,000, it is increasingly evident that in reality this is not true. Its clinical sequelae span a range of multiple organ systems, in particular the central nervous system, kidneys, skin and lungs. The management of TSC patients is heavily burdensome in terms of time and healthcare costs both for the families and for the healthcare system. Management options include conservative approaches, surgery, pharmacotherapy with mammalian target of rapamycin inhibitors and recently proposed options such as therapy with anti-EGFR antibody and ultrasound-guided percutaneous microwaves. So far, however, no systematically accepted strategy has been found that is both clinically and economically efficient. Thus, decisions are tailored to patients' characteristics, resource availability and clinical and technical expertise of each single center. This paper reviews the pathophysiology and the clinical (diagnostic-therapeutic) management of TSC.

Efficacy and Safety of Mammalian Target of Rapamycin Inhibitor Use-Long-term Follow-up of First Tuberous Sclerosis Complex Patient Treated De Novo With Sirolimus After Kidney Transplantation: A Case Report

Mammalian target of rapamycin inhibitors (mTORI) are increasingly used in the treatment of tuberous sclerosis complex (TSC) and as immunosuppressants after organ transplantation. In TSC patients, mTORI are the treatment of choice after kidney transplantation. It is still under debate if benefits from long-term mTORI use will not be limited by side effects.

MATERIALS AND METHODS

We report long-term follow-up data of the first TSC patient after kidney transplantation treated with sirolimus de novo. In 2005, a female patient was transplanted with a kidney graft after bilateral nephrectomy due to angiomyolipoma. Initial immunosuppressive treatment consisted of antithymocyte globulin, methylprednisolone, tacrolimus, and, due to TSC diagnosis, sirolimus. Creatinine level at discharge was 1.2 mg/dL.

RESULTS

Long-term mTORI use resulted in skin lesion regression (angiofibromas, "confetti" skin lesions, shagreen patch) and disease stabilization in brain, abdominal, and chest magnetic resonance imaging/computed tomography scans. Pulmonary function tests showed improvement in restriction and slow deterioration in obstruction and diffusion parameters. Sirolimus related adverse reactions were hyperlipidemia and hypertriglyceridemia and respiratory and urinary tract infections. No gastrointestinal or hematologic symptoms occurred. Sirolimus concentrations ranged between 1.7 and 8.2 ng/mL (mean 4.01 ± 2.09 ng/mL). Since 2009 proteinuria and slow increase in creatinine level have been observed. No biopsy was performed to establish etiology and potential association with mTORI. In 2017 creatinine level was 2.2 mg/dL.

CONCLUSION

The case of the patient confirms clinical effectiveness and acceptable safety of long-term mTORI treatment. Long-term mTORI use requires meticulous patient observation to optimize dosage, achieve immunosuppressive effect, and improve TSC manifestations with minimal side effects.

Recent Advances and Challenges of mTOR Inhibitors Use in the Treatment of Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a genetic condition characterized by the presence of benign, noninvasive, and tumor-like lesions called hamartomas that can affect multiple organ systems and are responsible for the clinical features of the disease. In the majority of cases, TSC results from mutations in the TSC1 and TSC2 genes, leading to the overactivation of the mammalian target of rapamycin (mTOR) signalling pathway, which controls several cell functions, including cell growth, proliferation, and survival. The establishment of a connection between TSC and mTOR led to the clinical use of drugs known as mTOR inhibitors (like rapamycin, also known as sirolimus and everolimus), which are becoming an increasingly interesting tool in the management of TSC-associated features, such as subependymal giant cell astrocytomas, renal angiomyolipomas, and also epilepsy. However, the intrinsic characteristics of these drugs and their systemic effects in such a heterogeneous condition pose many challenges in clinical practice, so that some questions remain unanswered. This article provides an overview of the pharmacological aspects of mTOR inhibitors about the clinical trials leading to their approval in TSC-related conditions and exposes current challenges and future directions associated with this promising therapeutic line.

Use of Topical Rapamycin in Facial Angiofibromas in Indian Skin Type

Introduction:

Facial angiofibromas (FA) are the most visible cutaneous manifestations in patients with tuberous sclerosis (TS), often resulting in stigmatization of the affected individuals. Recent studies have suggested that topical rapamycin may be an effective treatment for angiofibromas.

Aim:

To study the safety and efficacy of topical rapamycin in treatment of FA in Type IV–VI skin type.

Materials and Methods:

Five female patients with FA were included in the study, four of whom had TS, whereas one had isolated angiofibromas without systemic involvement. The age of the patients varied from 6 to 44 years. After baseline evaluation, they were advised to apply topical rapamycin (0.1–1%) in white soft paraffin base twice daily. Follow-up varied from 1 month to 6 months and is ongoing.

Results:

A sustained improvement was observed with respect to erythema, size as well as extent of the lesions as early as within 2 weeks of starting treatment. No side effects were observed. A correlation between duration of angiofibromas and effectiveness of treatment was noted.

Conclusion:

Topical rapamycin appears to be a safe and effective alternative to surgical or laser-based treatments in patients with FA. This treatment shows potential to be a first-line management for FA and appears safe to start in early childhood.

Facial angiofibromas of tuberous sclerosis treated with topical sirolimus in an Indian patient

Facial angiofibromas are the most visible and unsightly of all the cutaneous manifestations of tuberous sclerosis (TSC). A 17-year-old female, a known case of TSC, presented for the treatment of cosmetically disfiguring facial angiofibromas. She was started on twice daily application of 0.1% sirolimus ointment prepared from crushed tablets of sirolimus compounded in white soft paraffin. After 3 months of use, there was visible decrease in the erythema and the size of the angiofibromas. In an attempt to accelerate the response, the concentration was further increased to 1% sirolimus which was used for a month, resulting in a decrease not only in the size and redness but also in the number of the angiofibromas. The patient did not experience any cutaneous or systemic complications related to therapy. Sirolimus belongs to a novel class of anticancer drugs known as mTOR (mammalian target of Rapamycin) inhibitors. Sirolimus has been used as a targeted therapy for the renal and neurological manifestations of TSC. Topical preparation of sirolimus is not commercially available till date and hence preparations from crushed tablets or oral solution of sirolimus have been used with beneficial effects in treatment of angiofibromas especially in younger patients with flatter lesions. Randomized controlled trials are necessary to enable us to confirm the efficacy, long-term safety, the optimal dosage and possibility of reappearance once the drug is withdrawn. This is possibly the first case report of the use of topical sirolimus in India.

Tuberous sclerosis associated with polycystic kidney disease: effects of rapamycin after renal transplantation

Tuberous sclerosis is rarely associated with autosomal dominant polycystic kidney disease in the so-called tuberous sclerosis complex. This association leads to an increased frequency of end-stage renal disease. We present a patient suffering from both syndromes, who received a renal graft and anticalcineurinic drugs as immunosuppressive agents. Progressive titration of the drug was necessary in order to attain the effective doses due to the enzymatic induction caused by concomitant treatment with antiepileptic drugs. These high doses resulted in nephrotoxicity. Immunosuppressor treatment was switched to rapamycin, whereby an improvement in renal function and other signs of tuberous sclerosis and polycystic kidney disease was observed. This case report highlights both the efficacy and safety of rapamycin as an immunosuppressor treatment and its capacity for controlling other symptoms of these genetic-related disorders.

mTOR Inhibitors in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a genetic multiple organ system disorder that is characterized by the development of tumor-like lesions (hamartomas) and neurodevelopmental disorders. Mutations in the TSC1 and TSC2 tumor suppressor genes occur in the majority of patients with TSC, resulting in hyperactivation of the mammalian target of rapamycin (mTOR) signaling pathway and subsequent abnormalities in numerous cell processes. As a result, mTOR inhibitors such as sirolimus and everolimus have the potential to provide targeted therapy for patients with TSC. Everolimus is the first mTOR inhibitor approved as a treatment option in the USA and in Europe for patients with subependymal giant-cell astrocytomas (SEGAs) associated with TSC. The clinical evidence to date supports the use of mTOR inhibitors in a variety of TSC-associated disease manifestations, including SEGAs, renal angiomyolipoma, skin manifestations, and epilepsy. Furthermore, ongoing clinical trials evaluating mTOR inhibitors in TSC are underway, and the results of these studies are expected to provide further evidence that will firmly establish their role in this setting. This article will discuss the role of the mTOR pathway in TSC and review the pharmacokinetics, pharmacodynamics, clinical efficacy, and tolerability of mTOR inhibitors, along with their current place in clinical practice.

Everolimus: an mTOR inhibitor for the treatment of tuberous sclerosis

Tuberous sclerosis complex (TSC) is a devastating disease affecting virtually all organ systems of the body and is characterized by multiple hamartomas and neurodevelopmental disorders. The majority of patients with TSC have mutations in TSC1 or TSC2, resulting in constitutive activation of mTOR. Because the pathogenesis of the disease is mTOR hyperactivity, mTOR inhibitors have the potential to treat the underlying cause in TSC patients. Everolimus is the first mTOR inhibitor approved in the USA for the treatment of patients with subependymal giant-cell astrocytomas (SEGAs) associated with TSC. Evidence supports and ongoing studies are evaluating the role of mTOR inhibitors in the treatment of a wide spectrum of disease manifestations, including reduction in tumor volume (SEGAs, renal angiomyolipoma) and improvement in epilepsy, lung function and skin manifestations, including facial angiofibromas. In time, the use of mTOR inhibitors in patients with TSC will likely be very well established.

Topical 0.1% rapamycin for angiofibromas in paediatric patients with tuberous sclerosis: a pilot study of four patients

Tuberous sclerosis complex (TSC) is an autosomal dominant genodermatosis characterised by the development of hamartomatous tumours in multiple organs including the brain, skin, kidneys, heart and lungs. Facial angiofibromas are the most visible and unsightly of the cutaneous manifestations of TSC, often resulting in stigmatisation for both the affected individuals and their families. Current treatments include vascular laser, ablative lasers and other destructive techniques such as shave excision and electrodessication. For the best outcome these treatments have to be repeated throughout childhood and teenage years, necessitating multiple general anaesthetics. We report a pilot study of topical rapamycin in four children with TSC and facial angiofibromas. Two patients were trialled on 0.1% rapamycin in petrolatum and the other two patients with 0.1% rapamycin solution (Rapamune) applied topically. Both preparations were rapidly and equally effective, however the 0.1% in petrolatum was much better tolerated. Younger patients with smaller angiofibromas had the best response with near complete clearance. Both preparations were more cost effective than pulsed dye laser under general anaesthesia. Although larger studies are needed, this treatment shows a potential to be a first-line management for facial angiofibromas in TSC and appears safe to start in early childhood.

Targeting the dysregulated mammalian target of rapamycin pathway in organ transplantation: killing 2 birds with 1 stone

Dysregulation and hyperactivation of the mammalian target of rapamycin (mTOR) pathway define the molecular basis of the hamartoma syndromes, including Cowden syndrome, tuberous sclerosis complex (TSC)/lymphangioleiomyomatosis, and Peutz-Jeghers syndrome. Loss of the tumor suppressors phosphatase and tensin homolog (PTEN), TSC1, TSC2, and LKB1 results in uncontrolled growth of usually benign tumors in various organs that, however, frequently lead to organ failure. Therefore, organ transplantation is a common therapeutic option in distinct patients with hamartoma syndromes, especially those with TSC/lymphangioleiomyomatosis. mTOR inhibitors are currently used in allogeneic transplantation as immunosuppressants and for the treatment of a growing number of cancers with dysregulated mTOR/phosphoinositide 3-kinase pathway. This dual targeting provides the unique opportunity for mTOR inhibitors to affect hamartoma syndromes at the molecular level along with potent immunosuppression in transplanted individuals. Here, we review the molecular mechanisms of hamartoma syndromes and discuss the recent clinical progress in transplant patients with hamartomas. Combining the identification of novel molecular targets of the phosphoinositide 3-kinase/mTOR pathway with insights into the clinical effectiveness of current therapeutic strategies sets the stage for a broader translational potential essential for further progress both in the treatment of cancer and for transplantation.

The long and winding road to rational treatment of cancer associated with LKB1/AMPK/TSC/mTORC1 signaling

The liver kinase B1 (LKB1)/adenosine mono-phosphate-activated protein kinase (AMPK)/tuberous sclerosis complex (TSC)/mammalian target of rapamycin (mTOR) complex (mTORC1) cassette constitutes a canonical signaling pathway that integrates information on the metabolic and nutrient status and translates this into regulation of cell growth. Alterations in this pathway are associated with a wide variety of cancers and hereditary hamartoma syndromes, diseases in which hyperactivation of mTORC1 has been described. Specific mTORC1 inhibitors have been developed for clinical use, and these drugs have been anticipated to provide efficient treatment for these diseases. In the present review, we provide an overview of the metabolic LKB1/AMPK/TSC/mTORC1 pathway, describe how its aberrant signaling associates with cancer development, and indicate the difficulties encountered when biochemical data are extrapolated to provide avenues for rational treatment of disease when targeting this signaling pathway. A careful examination of preclinical and clinical studies performed with rapamycin or derivatives thereof shows that although results are encouraging, we are only half way in the long and winding road to design rationale treatment targeted at the LKB1/AMPK/TSC/mTORC1 pathway. Inherited cancer syndromes associated with this pathway such as the Peutz-Jeghers syndrome and TSC, provide perfect models to study the relationship between genetics and disease phenotype, and to delineate the complexities that underlie translation of biochemical and genetical information to clinical management, and thus provide important clues for devising novel rational medicine for cancerous diseases in general.

The diagnosis and treatment of subependymal giant cell astrocytoma combined with tuberous sclerosis

BACKGROUND

Subependymal giant cell astrocytoma develops in a small proportion of tuberous sclerosis patients. There are still several controversies on the early diagnosis of the tumor, treatment of hydrocephalus, and timing of operation, etc.

METHODS

From September 1996 to April 2006, 17 patients were admitted in neurosurgical department of "Beijing Tiantan Hospital". The authors analyzed medical records and followed up every case.

RESULTS

There are 18 tumors out of 17 patients. One patient had double tumors. Sixteen patients except one underwent tumor resection 17 times. Fifteen tumors out of 17 were gross totally removed; two were partially removed. One patient died of brain infarction postoperatively. Three out of 13 patients with preoperative hydrocephalus still needed ventriculoperitoneal shunt after tumor resection. There was no recurrence after total resection.

CONCLUSION

Diagnosis of tumor should be made by clinical criteria. Serial follow-up is essential for a suspected perimonro lesion to find tumor growth earlier. When there is growth, tumor should be removed as soon as possible. Hydrocephalus will resolve in most cases after tumor resection, while external drainage is suitable for emergent cases. Transcallosal and transcortical approaches are both effective to resect the tumor. Tumor will not recur after total removal.