Efficacy and safety of sirolimus treatment for intractable lymphatic anomalies: A study protocol for an open-label, single-arm, multicenter, prospective study (SILA)

Complex lymphatic anomalies: Molecular landscape and medical management

The lymphatic system is one of the most essential and complex systems in the human body. Disorders that affect the development or function of the lymphatic system can lead to multi-system complications and life-long morbidity. The past two decades have seen remarkable progress in our knowledge of the basic biology and function of the lymphatic system, the molecular regulators of lymphatic development, and description of disorders associated with disrupted lymphangiogensis. In this chapter we will touch on the clinical features of complex lymphatic anomalies, new molecular knowledge of the drivers of these disorders, and novel developmental therapeutics for lymphatic disease.

Sirolimus treatment for intractable lymphatic anomalies: an open-label, single-arm, multicenter, prospective trial

Introduction

Intractable lymphatic anomalies (LAs) include cystic lymphatic malformation (LM; macrocystic, microcystic, or mixed), generalized lymphatic anomaly, and Gorham-Stout disease. LAs can present with severe symptoms and poor prognosis. Thus, prospective studies for treatments are warranted. We conducted a prospective clinical trial of sirolimus for intractable LAs.

Methods

This was an open-label, single-arm, multicenter, prospective trial involving five institutions in Japan. All patients with LAs received oral sirolimus once daily, and the dose was adjusted to ensure that the trough concentration remained within 5-15 ng/mL. We prospectively assessed the drug response (response rate for radiological volumetric change in target lesion), performance state, change in respiratory function, visceral impairment (pleural effusion, ascites, bleeding, pain), laboratory examination data, quality of life (QOL), and safety at 12, 24, and 52 weeks of administration.

Results

Eleven patients with LAs (9 generalized lymphatic anomaly, 1 cystic LM, 1 Gorham-Stout disease) were treated with sirolimus, of whom 6 (54.5%; 95% confidence interval: 23.4-83.3%) demonstrated a partial response on radiological examination at 52 weeks of administration. No patients achieved a complete response. At 12 and 24 weeks of administration, 8 patients (72.7%) already showed a partial response. However, patients with stable disease showed minor or no reduction after 12 weeks. Adverse events, such as stomatitis, acneiform dermatitis, diarrhea, and fever, were common with sirolimus. Sirolimus was safe and tolerable.

Conclusion

Sirolimus can reduce the lymphatic tissue volume in LAs and may lead to improvements in clinical symptoms and QOL.

mTOR Pathway Substrates Present High Activation in Vascular Malformations and Significantly Decrease with Age

BACKGROUND

Vascular anomalies often result in aesthetic flaws, pain, and impair the quality of life. They require challenging treatments that frequently do not provide the desired results. The mammalian target of rapamycin (mTOR) is directly involved in the development of these malformations. However, the exact mechanism behind mTOR dysregulation has not been unambiguously defined. The purpose of this study is to investigate the activation of selected substrates of mTOR to partially assess its involvement in the disease process.

METHODS

We analyzed tissue samples collected from patients with vascular anomalies treated in our department. We included patients with histopathological diagnoses of lymphatic, venous, capillary malformations, mixed lesions, and a control group of healthy skin samples. We stained the samples using H and E and immunohistochemistry. We used primary antibodies against p70 S6 Kinase, 4EBP1, and p-4EBP1. We graded their color reactions. The statistical analyses were performed using the FactoMineR and factoextra R v.4.1 packages. p-values < 0.05 were considered statistically significant.

RESULTS

The analysis of 82 patients showed that healthy tissue vessels expressed lower levels of tested mTOR pathway substrates compared to high activation in vascular malformations. Elevated substrate expression in a comparison between sexes revealed higher P-4EBP1 expression in the female malformation group. We observed a decrease in mTOR substrate expression with age.

CONCLUSION

The higher expression of mTOR substrates in vascular malformations compared to healthy tissue confirms their involvement in abnormal vascular development. Age-related changes in mTOR substrate expression highlight the need for timely intervention. Our study contributes to the understanding of the mTOR signaling pathway in vascular malformations and highlights its potential as a therapeutic target, contributing to personalized medicine.

Monitoring of sirolimus in the whole blood samples from pediatric patients with lymphatic anomalies

In recent years, off-label use of sirolimus (SIR) has been gaining attention in the clinical practice. However, since it is critical to achieve and maintain therapeutic blood levels of SIR during treatment, the regular monitoring of this drug in individual patients must be implemented, especially in off-label indications of this drug. In this article, a fast, simple, and reliable analytical method for determining SIR levels in whole blood samples is proposed. Sample preparation based on dispersive liquid-liquid microextraction (DLLME) followed by liquid chromatography-mass spectrometry (LC-MS/MS) was fully optimized toward the analysis of SIR and proposed as a fast, simple, and reliable analytical method for determining the pharmacokinetic profile of SIR in whole-blood samples. In addition, the practical applicability of the proposed DLLME-LC-MS/MS method was evaluated by analyzing the pharmacokinetic profile of SIR in whole blood samples obtained from two pediatric patients suffering from lymphatic anomalies, receiving this drug as off-label clinical indication. The proposed methodology can be successfully applied in routine clinical practice for the fast and precise assessment of SIR levels in biological samples, thus allowing SIR dosages to be adjusted in real time during pharmacotherapy. Moreover, the measured SIR levels in the patients indicate the need for monitoring between doses to ensure the optimal pharmacotherapy of patients.

Sirolimus in the Treatment of Microcystic Lymphatic Malformations: A Systematic Review

Background: Genetic alterations in lymphatic development can lead to microcystic lymphatic malformations (micro LMs). LMs can have both microcystic and macrocytic components or be exclusively one or the other. LMs can result in serious, sometimes life-threatening, sequelae. Absent consensus guidelines, treatment has been largely empiric. Recent advances in our understanding of the pathogenesis of micro LMs have provided a foundation for novel therapeutic approaches. This review examines clinical data over the last 10 years on the role of sirolimus, an inhibitor of the PI3K/AKT/mTOR signaling pathway implicated in micro LM development, in the treatment of micro LM. Methods and Results: Systematic review of published clinical studies from January 1, 2011, to July 15, 2021, using the PubMed, Google Scholar, and Cochrane Reviews databases, and utilizing delimiters to focus specifically on sirolimus in the treatment of micro LM. A total of 16 studies were identified (13 case studies or case reviews; 3 prospective) that included 52 subjects treated with topical (n = 15) or oral (n = 37) sirolimus for micro LM. Clinically meaningful, long-term improvement (up to 3 years) was noted in 92% (46/50), mostly previously treated subjects. Sirolimus yielded improvements in key manifestations such as lymphatic leakage, bleeding, vesicle bulk, pain, and skin discoloration. Some subjects experienced a rapid onset of effect (within 2 weeks). No unexpected adverse events were seen. Conclusion: Sirolimus appears to be an effective and safe option in the management of cutaneous and complex micro LM. However, prospective, controlled trials are clearly needed to accurately elucidate the benefits and risks of sirolimus in the management of micro LM. ClinicalTrials.gov Identifier: NCT05050149.

Interventional therapy of extracranial arteriovenous malformations of the head and neck—A systematic review

Objectives

The primary aim of this study was to conduct a meta-analysis of the literature on interventional treatment for patients with extracranial AVM of the head and neck to identify a superior treatment. The secondary aim was to evaluate the methodological quality of associated articles published between 2000–2020.

Methods

The literature search was conducted on PubMed, Embase, the Cochrane Library, and scholar.google.com. Studies, meeting the acceptable reference standard underwent meta-analysis. All identified literature underwent methodological quality analysis.

Results

Of 1560 screened articles, 56 were included in the literature review. Appropriate diagnostic tests were reported in 98% of included articles. 13% of included articles did not specify the embolization agent. Outcome analysis varied throughout. 45% of the authors used radiographic imaging for follow-up. 77% specified the span of follow-up of their entire patient collective. Two articles met the inclusion criteria for meta-analysis. Curing rate of transarterial ethanol embolization for intraosseous AVM was 83% with a complication rate of 58%. Curing rate of ethanol combined with NBCA or Onyx in soft tissue AVM was 18% with a complication rate of 87%.

Conclusion

Our literature review revealed an absence of treatment or reporting standards for extracranial AVM of the head and neck. The meta-analysis is comprised of two articles and methodological quality is heterogeneous. We recommend implementing consistent reporting standards to facilitate comparability of studies and to provide robust data for the development of an evidence-based treatment strategy.

Advances in knowledge

Meta-analysis showed a favorable radiological outcome for intraosseous AVM when treated with intraarterial ethanol embolization. Our analysis demonstrated that the published data on extracranial AVMs of the head and neck is lacking in consistency and quality, prompting agreement for the need of standardized reporting on AVM treatments.

Indications and Limitations of Sirolimus in the Treatment of Vascular Anomalies-Insights From a Retrospective Case Series

BACKGROUND

Despite recent developments, the role of sirolimus in the heterogeneous spectrum of vascular anomalies is yet to be defined, in terms of indication, dosage, and therapy duration, recognizing both its potential and limitations.

METHODS

We retrospectively analyzed 16 children with vascular anomalies treated with sirolimus in two pediatric centers between 2014 and 2020 [male: n = 7, the median age at diagnosis: 4.6 months (range, 0-281.4)]. In addition, repetitive volumetric analyses of the vascular anomalies were performed when possible (11 cases).

RESULTS

Ten patients were diagnosed with vascular malformations and 6 with vascular tumors. The mean therapy duration was 27.2 months (range, 3.5-65). The mean sirolimus level was 8.52 ng/ml (range, 5.38-12.88). All patients except one with central conducting lymphatic anomaly responded to sirolimus, with the most noticeable volume reduction in the first 4-6 months. Additional administration of vincristine was needed in five patients with kaposiform hemangioendothelioma and yielded a response, even in cases, refractory to sirolimus monotherapy. As a single agent, sirolimus led to impressive improvement in a patient with another vascular tumor-advanced epithelioid hemangioendothelioma. Complicated vascular malformations required long-term sirolimus therapy. Side effects of sirolimus included mucositis and laboratory abnormalities. No major infectious episodes were recorded. An infant with COVID-19, diagnosed while on sirolimus therapy, presented with a mild course.

CONCLUSION

In the current series, we reported limitations of sirolimus as monotherapy, addressing the need to redefine its indications, and explore combination regimens and multimodal treatment strategies. Tools for objective evaluation of response trends over time could serve as a basis for the establishment of future therapeutic algorithms.

Management of refractory chylothorax in the neonatal intensive care unit: A 22-year experience

BACKGROUND

The aim was to assess the therapeutic strategy of patients with chylothorax in a neonatal intensive care unit.

METHODS

Twenty-eight infants with chylothorax were included in this study. Their clinical characteristics and outcomes were reviewed retrospectively.

RESULTS

The male-to-female ratio was 1:1. The mean gestational age and birthweight were 35.1 ± 3.5 weeks and 2,692 ± 791 g, respectively. Eighteen patients were diagnosed with congenital chylothorax; chylothorax occurred postoperatively in 10 patients. Chromosomal anomalies were diagnosed in 8 patients. Six patients received surgical therapy, such as pleurodesis, thoracic duct ligation, or lymphaticovenous anastomosis. Two patients required surgery due to resistance to pleurodesis. In surgically managed patients, the daily maximum amount of pleural effusion (mL)/bodyweight (kg) ratio was significantly larger than in non-surgically managed patients: 229.0 ± 180.5 versus 59.7 ± 49.2 mL/kg. In the receiver operating characteristic analysis of the daily maximum amount of pleural effusion/bodyweight ratio, the area under the curve was 0.889 when the cut-off value was 101 mL/kg, and the sensitivity was 0.8333 and the specificity was 0.8095 (P = 0.0059).

CONCLUSIONS

Pleurodesis using OK432 could become a surgical first-line therapy for chylothorax even for neonates. It was important to initiate pleurodesis for refractory chylothorax at an earlier stage. A daily chylous effusion/bodyweight ratio of >101 mL/kg was a good predictor and seemed to be a useful parameter for prompt surgical intervention.

Neonatal Generalized Lymphatic Anomaly with Skin Involvement

Generalized lymphatic anomaly (GLA) is a rare congenital disorder of lymphatic development, presenting with multiple lymphatic malformations in different organs and tissues. Here, we present a case of a female neonate prenatally diagnosed with foetal hydrops and a mediastinal cystic lymphatic malformation that showed postnatal expansive and infiltrative growth into the major airways, compromising mechanical ventilation and further management of the neonate. Complications that arose during surgical treatment of mediastinal structures led to the patient’s death. Lymphatic malformations were also noted in the skin at birth. Furthermore, a skin biopsy performed immediately after birth and the autopsy revealed an extremely rare diagnosis of combined macrocystic and microcystic forms of GLA with skin involvement.

Update on infantile hemangioma

The International Society for the Study of Vascular Anomalies classifies vascular anomalies into vascular tumors and vascular malformations. Vascular tumors are neoplasms of endothelial cells, among which infantile hemangiomas (IHs) are the most common, occurring in 5%-10% of infants. Glucose transporter-1 protein expression in IHs differs from that of other vascular tumors or vascular malformations. IHs are not present at birth but are usually diagnosed at 1 week to 1 month of age, rapidly proliferate between 1 and 3 months of age, mostly complete proliferation by 5 months of age, and then slowly involute to the adipose or fibrous tissue. Approximately 10% of IH cases require early treatment. The 2019 American Academy of Pediatrics clinical practice guideline for the management of IHs recommends that primary care clinicians frequently monitor infants with IHs, educate the parents about the clinical course, and refer infants with high-risk IH to IH specialists ideally at 1 month of age. High-risk IHs include those with life-threatening complications, functional impairment, ulceration, associated structural anomalies, or disfigurement. In Korea, IHs are usually treated by pediatric hematology-oncologists with the cooperation of pediatric cardiologists, radiologists, dermatologists, and plastic surgeons. Oral propranolol, a nonselective beta-adrenergic antagonist, is the first-line treatment for IHs at a dosage of 2-3 mg/kg/day divided into 2 daily doses maintained for at least 6 months and often continuing until 12 months of age. Topical timolol maleate solution, a topical nonselective beta-blocker, may be used for small superficial type IHs at a dosage of 1-2 drops of 0.5% gel-forming ophthalmic solution applied twice daily. Pulse-dye laser therapy or surgery is useful for the treatment of residual skin changes after IH involution.

Efficacy of Initial Sirolimus Therapy for 27 Patients with Intractable Lymphatic Malformations

OBJECTIVE/HYPOTHESIS

To evaluate the efficacy of initial sirolimus therapy in the treatment of intractable head and neck lymphatic malformations (LMs) in children.

STUDY DESIGN

Prospective open-label study.

METHODS

In this study, Twenty-seven children diagnosed with LMs were given oral sirolimus as primary treatment over a minimum 6-month trial. The major parameter to evaluate therapeutic outcome was percentage of lesion volume change compared with baseline. Average serum sirolimus concentrations, and adverse side effects, were monitored throughout the study period.

RESULTS

Fifteen girls and twelve boys, average age 27 months (16 days-171 months), constitute the study group. Treatment was deemed effective for twenty-three participants, judged as fair in seven, good in nine, and excellent in seven. Two patients had minimal improvement, and two had increased volume to some degree. Effectiveness differed among LMs subtypes with responsiveness of macrocystic LMs exceeding that of microcystic LMs (P < .05). Adverse drug reactions totaled 27 events in ten patients, the majority being mild with upper respiratory infections being most common.

CONCLUSIONS

Sirolimus as initial therapy is effective in decreasing lesion volume in intractable LMs in head and neck region, especially in macrocystic subtypes. Although most cases cannot be completely cured, side effects are few and tolerable.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1902-1908, 2021.

Cardamonin inhibits cell proliferation by caspase-mediated cleavage of Raptor

The antiproliferative effect of cardamonin on mTORC1 is related with downregulation of Raptor. We investigated the mechanism that cardamonin decreases Raptor expression through caspase-mediated protein degradation. SKOV3 cells and HeLa cells were pretreated with caspase inhibitor z-VAD-fmk for 30 min and then exposed to different doses of cardamonin and cisplatin, respectively. We analyzed the gene expression of caspases based on TCGA and GTEx gene expression data in serous cystadenocarcinoma and normal tissues, monitored caspase activity by caspase colorimetric assay kit, detected expression of mTORC1-associated proteins and apoptosis-associated proteins by western blotting, and finally detected cell viability by methyl thiazolyl tetrazolium (MTT) assay. A different expression of caspases except caspase-1 was found between serous cystadenocarcinoma and normal tissues. Raptor was cleaved when caspases were activated by cisplatin and caspase-6/caspase-8 was activated by cardamonin in SKOV3 cells. We further used a monoclonal antibody recognizing the N-terminal part of Raptor to find that Raptor was cleaved into a smaller fragment of about 70 kDa by cardamonin and was rescued by z-VAD-fmk treatment. As a result of Raptor cleavage, mTORC1 activity was decreased and cell viability was inhibited, while cell apoptosis was induced in SKOV3 cells. Notably, similar results are only observed in HeLa cells with a high dose of cardamonin. We concluded that caspase-mediated cleavage of Raptor might be an important mechanism in that cardamonin regulated Raptor and mTORC1 activity.

The Impact of Adjuvant Sirolimus Therapy in the Surgical Management of Scrotal Slow-Flow Vascular Malformations

OBJECTIVE

To describe the effects of oral sirolimus administered before and after surgical resection of slow-flow vascular malformations of the scrotum in pediatric patients.

METHODS

Retrospective review of 3 patients presenting with complex lymphatic-venous malformations of the scrotum who received adjuvant oral sirolimus 3 months before and 3 months after surgical resection. Demographic data, clinical course, imaging findings, and management strategies were reviewed for each patient.

RESULTS

In each of the 3 patients, there was a significant volume reduction of the lesion within the 3 months after initial dose of sirolimus. Scarce lymphatic leakage during and after surgery was reported, associated with an adequate wound healing. Two years after the last postsurgical dose of sirolimus, all patients remain asymptomatic without any lymphatic leakage or lesion recurrence.

CONCLUSION

Combined lymphatic-venous vascular malformations of the male genitalia are rare but associated with high morbidity and challenging treatment options. Pre- and postsurgical adjuvant treatment with oral sirolimus seems to be a promising therapeutic option that provides reduction of the lesion size before surgery and improvement of postsurgical recovery and wound healing.

Gorham-Stout disease successfully treated with sirolimus (rapamycin): a case report and review of the literature

BACKGROUND

Gorham-Stout disease (GSD) is a rare disease characterized by bone lesions and osteolysis. Therapy usually involves surgical resection. Sirolimus (Rapamycin) is used in some patients with GSD but the efficacy and safety of Sirolimus remains unclear. We propose that Sirolimus may be a novel therapeutic for GSD and present a case and review of literature that supports this.

CASE PRESENTATION

We presented a 1-year-old boy with GSD involving osteolysis of the right humerus with fracture of the left femur complicated by an effusion in the right pleural cavity. X-rays showed osteolysis in the right clavicle. A large pleural effusion was observed on the right-side, and the left lung was significantly compressed. X-rays also showed a fracture of the left femur. A femoral biopsy was performed that showed necrotic tissue in the cortical bone and a large number of irregularly shaped capillaries that proliferated within the necrotic tissue. Dilated lymphatic vessels were seen adjacent to the cortex, with fibrous tissue hyperplasia. We prescribed sirolimus, which is an oral mTOR inhibitor, for two consecutive years. The boy recovered well without other progressive bone lesions and participates in normal daily activities. His growth and development are the same as that of his peers.

DISCUSSION AND CONCLUSION

Gorham-Stout disease is a rare and enigmatic disease characterized by the presentation of an intraosseous lymphatic anomaly (LM), which results in progressive bone resorption. Based on this case report and a literature review, we conclude that sirolimus may be an effective alternative medication for GSD.

Immunologic Effects of Sirolimus in Patients With Vascular Anomalies

Emerging data have suggested that sirolimus may be a treatment option for complicated vascular anomalies (VAs). The present study aimed to investigate the immunologic effects of sirolimus treatment for 6 months in patients with VAs. Blood samples obtained from the patients enrolled in 2 multicenter studies to investigate the efficacy of sirolimus for VAs before and after sirolimus treatment for 6 months were used. Data for total white blood cell count, absolute lymphocyte count, serum immunoglobulins (Igs) levels (IgG, IgA, IgM), lymphocyte proliferation assays with mitogens including phytohemagglutinin and concanavalin A, and flow cytometric analysis of lymphocyte subsets were evaluated. A total of 18 patients with VAs receiving sirolimus treatment were included in the study. Comparisons of white blood cell, absolute lymphocyte count, IgG, IgA, IgM, and reaction rates of phytohemagglutinin and concanavalin A revealed no significant differences before and after treatment. No significant differences were observed in the absolute counts of lymphocyte subtypes before and after treatment, except for regulatory T-cell counts, which were significantly decreased after treatment. Severe infections were not observed during sirolimus treatment. The immunologic parameters assessed in the present study were hardly affected by sirolimus treatment for 6 months in patients with VAs.

Emerging Roles for Lymphatics in Chronic Liver Disease

Chronic liver disease (CLD) is a global health epidemic causing ∼2 million deaths annually worldwide. As the incidence of CLD is expected to rise over the next decade, understanding the cellular and molecular mediators of CLD is critical for developing novel therapeutics. Common characteristics of CLD include steatosis, inflammation, and cholesterol accumulation in the liver. While the lymphatic system in the liver has largely been overlooked, the liver lymphatics, as in other organs, are thought to play a critical role in maintaining normal hepatic function by assisting in the removal of protein, cholesterol, and immune infiltrate. Lymphatic growth, permeability, and/or hyperplasia in non-liver organs has been demonstrated to be caused by obesity or hypercholesterolemia in humans and animal models. While it is still unclear if changes in permeability occur in liver lymphatics, the lymphatics do expand in number and size in all disease etiologies tested. This is consistent with the lymphatic endothelial cells (LEC) upregulating proliferation specific genes, however, other transcriptional changes occur in liver LECs that are dependent on the inflammatory mediators that are specific to the disease etiology. Whether these changes induce lymphatic dysfunction or if they impact liver function has yet to be directly addressed. Here, we will review what is known about liver lymphatics in health and disease, what can be learned from recent work on the influence of obesity and hypercholesterolemia on the lymphatics in other organs, changes that occur in LECs in the liver during disease and outstanding questions in the field.

A Large Skull Defect Due to Gorham-Stout Disease: Case Report and Literature Review on Pathogenesis, Diagnosis, and Treatment

A 24-year old man was referred to the Erasmus MC Bone Center because of an asymptomatic increasing skull defect of the left parietal bone. The defect was first noticed at the age of six, and gradually increased over the years. His medical history was unremarkable, without any known trauma and a negative family history for bone diseases. Laboratory tests showed a low vitamin D level without other abnormalities. Particularly, there was no increase in markers of inflammation or bone turnover. CT-scans of the skull showed an osteolytic region of the parietal skull bone, with a two-centimeter increase in diameter over 9 years. Contrast enhanced MRI showed lymphangiogenic invasion, which was compatible with our suspicion of Gorham-Stout disease. The patient was referred to the neurosurgeon for treatment with a bone graft while considering additional drug treatment. Gorham-Stout or vanishing bone disease is a rare entity characterized by progressive osteolysis with lymphangiogenic bone invasion. Although already reported in 1838, currently the diagnosis and treatment of Gorham-Stout disease is still challenging. The underlying pathophysiology is not clarified yet and several theories exist. The disease usually affects persons younger than 40 years and the majority present with bone disease of the maxillofacial region, the upper extremities or the torso. The clinical presentation includes most frequently pain, swelling, and functional impairment of the affected region, but the disease can also be asymptomatic. Laboratory investigations are usually normal, and diagnosis is based upon imaging and sometimes pathology examination of affected bone tissue. Treatment is experimental and there is no general consensus about the best option due to lack of randomized controlled trials. Case reports showed patients treated with bisphosphonates, interferon-alpha, anti-VEGF therapy, mTOR inhibitors, and radiotherapy. There are some reports of surgery with prosthetic or bone grafts but no long-term follow-up data exist. This paper describes a unique case of Gorham-Stout disease of the parietal skull bone and discusses the current state of knowledge about this rare bone disease.