Efficacy and Safety of Sirolimus in the Treatment of Complicated Vascular Anomalies

Operative Management of Intra-abdominal Lymphatic Malformations in Children: A Single Tertiary Center Experience

BACKGROUND

Intra-abdominal lymphatic malformations (LMs) are relatively rare congenital anomalies and can be divided into intra- and retroperitoneal subgroups. This study aims to evaluate the outcomes after surgical resection of intraperitoneal LMs in children.

METHODS

The records of all patients ≤16 years of age with intraperitoneal LMs managed at our tertiary center between 2007-2022 were reviewed. Patients with retroperitoneal LMs were excluded. Our preferred approach is surgical exploration for large (>5 cm), symptomatic lesions if they are potentially resectable on imaging.

RESULTS

A total of 12 patients (10 males) were diagnosed with intraperitoneal LMs located in the small bowel mesentery or omentum at a median age of 6.6 (range, 0.6-14.4) years. Ten (83%) patients presented with acute symptoms, including abdominal pain (n = 8; 67%) and vomiting (n = 3; 25%). Two (17%) intraperitoneal LMs were found on imaging performed for other reasons. Surgical exploration was performed in 11/12 (92%) cases. Intestinal volvulus around a mesenteric macrocyst had occurred in 4 (36%) patients. Complete macroscopic resection was achieved in 10/11 (91%) patients. Most lesions were localized to a short intestinal segment. One mixed type LM with an extensive mesenteric involvement was biopsied as the lesion was deemed to be unresectable in preoperative imaging and the diagnosis was initially unclear. There was one recurrence (8%) during postoperative follow-up on imaging (median 3.6 (range, 1.5-6.9) years) but the patient has remained asymptomatic and not undergone interventions. 6/8 (75%) of screened intraperitoneal LMs were positive for a somatic PIK3CA mutation.

CONCLUSIONS

Most large, pedunculated macrocystic LMs in the small bowel mesentery or omental location were amenable to macroscopic resection. Intraperitoneal LMs tend to present with acute symptoms including a risk for intestinal volvulus based on anatomical location. Our results suggest low recurrence rates or need for further interventions over follow-up.

LEVEL OF EVIDENCE

III.

Somatic Loss-of-Function PIK3R1 and Activating Non-hotspot PIK3CA Mutations Associated with Capillary Malformation with Dilated Veins (CMDV)

Common capillary malformations are red vascular skin lesions, most commonly associated with somatic activating GNAQ or GNA11 mutations. We focused on capillary malformations lacking such a mutation to identify previously unreported genetic causes. We used targeted next-generation sequencing on 82 lesions. Bioinformatic analysis allowed the identification of 9 somatic pathogenic variants in PIK3R1 and PIK3CA, encoding for the regulatory and catalytic subunits of phosphoinositide 3-kinase, respectively. Recharacterization of these lesions unraveled a common phenotype: a pale capillary malformation associated with visible dilated veins. Primary endothelial cells from 2 PIK3R1-mutated lesions were isolated, and PI3k-Akt-mTOR and RAS-RAF-MAPK signaling were assessed by western blot. This unveiled an abnormal increase in Akt phosphorylation, effectively reduced by PI3K pathway inhibitors, such as mTOR, Akt, and PIK3CA inhibitors. The effects of mutant PIK3R1 were further studied using zebrafish embryos. Endothelium-specific expression of PIK3R1 mutants resulted in abnormal development of the posterior capillary-venous plexus. In summary, capillary malformation associated with visible dilated veins emerges as a clinical entity associated with somatic pathogenic variants in PIK3R1 or PIK3CA (nonhotspot). Our findings suggest that the activated Akt signaling can be effectively reversed by PI3K pathway inhibitors. In addition, the proposed zebrafish model holds promise as a valuable tool for future drug screening aimed at developing patient-tailored treatments.

Targeted treatments for vascular malformations: current state of the art

Vascular malformations, which arise from anomalies in angiogenesis, encompass capillary, lymphatic, venous, arteriovenous, and mixed malformations, each affecting specific vessel types. Historically, therapeutic options such as sclerotherapy and surgery have shown limited efficacy in complicated malformations. Most vascular malformations stem from hereditary or somatic mutations akin to oncogenic alterations, activating the PI3K-AKT-mTOR, RAS-MAPK-ERK, and G-protein coupled receptor pathways. Recognizing the parallels with oncogenic mutations, we emphasize the potential of targeted molecular inhibitors in the treatment of vascular malformations by repurposing anticancer drugs. This review delves into the recent development and future use of such agents for the management of slow- and fast-flow vascular malformations, including in more specific situations, such as prenatal treatment and the management of associated coagulopathies.

Intraorbital lymphatic-venous malformation in an adult patient: is sirolimus the key?

Intraorbital lymphatic-venous malformations are rare lesions that represent a therapeutic challenge given their location and high rate of recurrence, with only a few cases in adult patients having been published in the literature. We present the case of a 30-year-old male with a right intraorbital lymphatic-venous malformation treated with sirolimus at a dose of 4 mg/day with complete clinical and radiologic remission. Mild cold-like symptoms ensued during the first week of treatment and elevation of liver function enzymes and D-dimer occurred in the context of acute SARS-CoV-2 pneumonia. No major adverse effects were documented. After 18 months of treatment, the patient remains asymptomatic and ophthalmologic examinations including optical coherence tomography and visual field test are within normal values.

Sirolimus for vascular anomalies in the first year of life: a systematic review

Evidence on effectiveness and safety of sirolimus in congenital vascular anomalies in infancy is lacking. We aim to systematically review the efficacy and safety of sirolimus in treating congenital VA in infancy. We searched for and included all studies evaluating sirolimus for VA in the first year of life. The primary outcome was effectiveness. The secondary outcome was safety. We included 84 case series and reports (172 participants). Sirolimus decreased the size of the VA in >50% of participants, most of whom had minor transient side effects, and 27% had no adverse effects at all. When categorized by age (<1 month, 1-5 months and 6-12 months), the effectiveness was similar in all age groups. Available evidence suggests that sirolimus is effective and well tolerated. The effectiveness of sirolimus should be evaluated in a well-designed randomized controlled or observational studies.

PIK3CA-Related Disorders: From Disease Mechanism to Evidence-Based Treatments

Recent advances in genetic sequencing are transforming our approach to rare-disease care. Initially identified in cancer, gain-of-function mutations of the PIK3CA gene are also detected in malformation mosaic diseases categorized as PIK3CA-related disorders (PRDs). Over the past decade, new approaches have enabled researchers to elucidate the pathophysiology of PRDs and uncover novel therapeutic options. In just a few years, owing to vigorous global research efforts, PRDs have been transformed from incurable diseases to chronic disorders accessible to targeted therapy. However, new challenges for both medical practitioners and researchers have emerged. Areas of uncertainty remain in our comprehension of PRDs, especially regarding the relationship between genotype and phenotype, the mechanisms underlying mosaicism, and the processes involved in intercellular communication. As the clinical and biological landscape of PRDs is constantly evolving, this review aims to summarize current knowledge regarding PIK3CA and its role in nonmalignant human disease, from molecular mechanisms to evidence-based treatments.

Sirolimus is effective and safe in childhood relapsed-refractory autoimmune cytopenias: A multicentre study

Autoimmune cytopenias are a heterogeneous group of disorders characterized by immune-mediated destruction of haematopoietic cell lines. Effective and well-tolerated treatment options for relapsed-refractory immune cytopenias are limited. In this study, the aim was to evaluate the efficacy and safety of sirolimus in this disease group within the paediatric age group. The study enrolled patients in the paediatric age group who used sirolimus with a diagnosis of immune cytopenia between December 2010 and December 2020, followed at six centres in Turkey. Of the 17 patients, five (29.4%) were treated for autoimmune haemolytic anaemia (AIHA), six (35.2%) for immune thrombocytopenic purpura (ITP) and six (35.2%) for Evans syndrome (ES). The mean response time was 2.7 months (range, 0-9 months). Complete response (CR) and partial response (PR) were obtained in 13 of 17 patients (76.4%) and nonresponse (NR) in four patients (23.5%). Among the 13 patients who achieved CR, three of them were NR in the follow-up and two of them had remission with low-dose steroid and sirolimus. Thus, overall response rate (ORR) was achieved in 12 of 17 patients (70.5%). In conclusion, sirolimus may be an effective and safe option in paediatric patients with relapsed-refractory immune cytopenia.

A case report of primary Kaposiform hemangioendothelioma of the humerus

To examine the clinicopathological and immunohistochemical features of Kaposiform hemangioendothelioma (KHE) and discuss its differential diagnosis and prognosis. A patient with KHE was examined; the patient's clinical and histopathological features were observed, and the expression levels of CD31, CD34, ERG, D2-40, SMA, GLUT-1, and LANA-1 were assessed. The patient was a four-year-old child with primary KHE of the humerus. She was admitted to the hospital because of pain in the right elbow joint and limited movement for more than 2 years. Imaging revealed Langerhans cell histiocytosis. The child was not diagnosed with Kasabach-Merritt phenomenon (KMP). The tumor consists of multiple hemangiomatous nodules with infiltrative growth separated by fibrous connective tissue. The proliferating hemangiomatoid nodules consisted of crisscrossing short spindle-shaped cell bundles and erythrocyte-containing lacunar or crescentic vessels. Immunohistochemical staining showed that the tumor cells diffusely expressed CD31, CD34, ERG, and other vascular endothelium-derived markers; further, the tumor cells expressed neither GLUT-1 nor LANA-1. The patient's general condition improved after surgical resection. There was no tumor recurrence after more than 8 months of follow-up. Primary KHE of the humerus is a rare vasculogenic tumor. It presents with morphological features that require an accurate differential diagnosis.

Therapy with sirolimus in vascular anomalies: the experience of two Italian centers on 14 pediatric patients

Introduction

Vascular anomalies (VAs) constitute a heterogeneous group of tumors and malformations capable of inducing significant clinical events in specific patients, such as the compression of vital organs, pain, functional impairment, or acquired coagulopathy. Molecular investigations into the underlying mechanisms of VAs have unveiled the frequent involvement of the PI3 K/AKT/mTOR pathway. Sirolimus, a specific mTOR inhibitor, has emerged as a potential therapeutic agent; however, its routine clinical application in complex VAs is currently restricted by a lack of extensive clinical experience.

Methods

Between 2015 and 2024, we administered sirolimus to 14 pediatric patients with various types of vascular anomalies in two Italian centers, subjecting them to clinical and instrumental follow-up to investigate its efficacy and the possible occurrence of adverse events.

Results

An overall improvement in or stability of their vascular anomalies was reported by 86% of patients. We also assessed toxicity, noting a low prevalence of life-threatening adverse events: only one case of sepsis was reported in a patient with a severe clinical condition, and four cases of recurrent aphthosis (28%) were reported. The most common side effect was dyslipidemia, with 43% of patients developing hypercholesterolemia (21%) or hypertriglyceridemia (21%), although these patients generally did not reach severe levels.

Discussion

In line with data in the literature, according to our experience, medical therapy with sirolimus should be considered in pediatric patients affected by vascular anomalies.

Complications of pediatric macrocystic lymphatic malformations of the head and neck: a survival analysis of treated and untreated patients

OBJECTIVE

To compare events of recurrent swelling between treated and untreated patients with macrocystic lymphatic malformations of the head and neck not involving the airway. The frequency and timing of emergency department (ED) visits related to the event were analysed to provide data on efficacy and ideal timing of treatment.

METHODS

A 5-year retrospective review of a hospital database was conducted reviewing 35 patients (15 female, 20 male; mean age 3.9 years) with macrocystic lymphatic malformations of the head and neck not involving the airway. Patients treated with oral medications were excluded. A survival analysis was performed comparing the incidence of recurrent swelling of the malformation. A Cox regression analysis was conducted using age, gender, diameter of lymphatic malformation at presentation, and echogenicity on US as covariates. Fisher's test and mean comparisons were performed to correlate the populations baselines and the number and frequency of ED visits between the 2 groups.

RESULTS

Thirteen patients underwent sclerotherapy soon after initial presentation and 22 elected for observation. The two baseline populations differed at presentation with the treatment group being younger (1.4 ± 2.4 vs. 5.4 ± 6.3 years, p = 0.03) and with larger lesions (5.7 ± 2.7 vs. 4.0 ± 1.7 cm p = 0.03). Mean follow-up time was 2.7 years. Survival analysis showed 1 or multiple recurrences affected 16 patients in the untreated group and 3 patients in the treated group. (p = 0.04). Age, gender, diameter of the lesion at presentation and increased echogenicity on US were not predictive factors of recurrence. Although the probability of visiting the ED at least once did not differ between the two groups (p = 0.42), patients from the non-treatment group were more likely to visit the ED more than once (p = 0.03).

CONCLUSIONS

Sclerotherapy treatment may reduce the chance of recurrent swelling or an event after initial presentation to the ED.

NRASQ61R mutation drives elevated angiopoietin-2 expression in human endothelial cells and a genetic mouse model

BACKGROUND

Angiopoietin-2 (Ang-2) is increased in the blood of patients with kaposiform lymphangiomatosis (KLA) and kaposiform hemangioendothelioma (KHE). While the genetic causes of KHE are not clear, a somatic activating NRASQ61R mutation has been found in the lesions of KLA patients.

PROCEDURE

Our study tested the hypothesis that the NRASQ61R mutation drives elevated Ang-2 expression in endothelial cells. Ang-2 was measured in human endothelial progenitor cells (EPC) expressing NRASQ61R and a genetic mouse model with endothelial targeted NRASQ61R. To determine the signaling pathways driving Ang-2, NRASQ61R EPC were treated with signaling pathway inhibitors.

RESULTS

Ang-2 levels were increased in EPC expressing NRASQ61R compared to NRASWT by Western blot analysis of cell lysates and ELISA of the cell culture media. Ang-2 levels were elevated in the blood of NRASQ61R mutant mice. NRASQ61R mutant mice also had reduced platelet counts and splenomegaly with hypervascular lesions, like some KLA patients. mTOR inhibitor rapamycin attenuated Ang-2 expression by NRASQ61R EPC. However, MEK1/2 inhibitor trametinib was more effective blocking increases in Ang-2.

CONCLUSIONS

Our studies show that the NRASQ61R mutation in endothelial cells induces Ang-2 expression in vitro and in vivo. In cultured human endothelial cells, NRASQ61R drives elevated Ang-2 through MAP kinase and mTOR-dependent signaling pathways.

Ocular and orbital tumors in childhood

Pediatric tumors of the eye and orbit can be benign or malignant as well as congenital or acquired and are usually distinctively different than those seen in adults. Although most of these neoplasms are benign (eg, dermoid cyst, chalazion, molluscum), their location near and within a vital organ can result in serious dermatologic and ophthalmologic sequelae. Lesions discussed include vascular lesions, retinoblastomas (the most common primary pediatric intraocular malignancy), rhabdomyosarcoma (the most common primary pediatric orbital malignancy), Langerhans cell histiocytosis, and metastatic lesions to the orbit (neuroblastoma, Ewing sarcoma). Although cysts and ocular melanoma can occur within the pediatric population, these conditions are covered in other contributions in this issue of Clinics in Dermatology.

Gene expression profiling of venous malformations identifies the role of SDC1 in venous endothelial cells

Objective

To obtain insight into the molecular process implicated in venous malformations (VMs) and identify potential targets for treatment of VMs, this study profiled the gene expression pattern in VMs, investigated alterations of syndecan-1 (SDC1) expression in VMs, and tested the hypothesis that aberrant SDC1 expression triggers abnormal angiogenesis and VM development.

Methods

Microarray analysis was performed to identify differentially expressed genes (DEGs) on a transcriptome-wide level in VMs and conjunctive normal. Gene Ontology molecular functional analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis were carried out to establish enhancement of biological signaling pathways involved in VMs. Among the DEGs, we focused on SDC1, which is involved in matrix remodeling, cell proliferation and invasion, and angiogenesis. SDC1 expression in VMs was verified by qRT-PCR, western blotting, and immunohistochemistry. Loss-of-function of SDC1 was achieved in human umbilical vein endothelial cells (HUVECs) by siRNA to investigate the roles of SDC1 in cell migration, invasion, and angiogenesis.

Results

Compared with control tissue, the transcriptome study identified 274 upregulated DEGs and 3 downregulated DEGs. The transcript and protein levels of SDC1 were significantly decreased in VMs compared with normal tissue. Inhibition of SDC1 enhanced HUVEC migration, invasion, and angiogenesis.

Conclusion

Our genome-wide microarray analysis suggests the involvement of numerous genes in VMs. Among them, SDC1 plays a substantial role in the process of angiogenesis and development of VMs. SDC1 may represent a potential target for a molecular therapy for VMs.

Targeted therapy for capillary-venous malformations

Sporadic venous malformations are genetic conditions primarily caused by somatic gain-of-function mutation of PIK3CA or TEK, an endothelial transmembrane receptor signaling through PIK3CA. Venous malformations are associated with pain, bleedings, thrombosis, pulmonary embolism, esthetic deformities and, in severe cases, life-threatening situations. No authorized medical treatment exists for patients with venous malformations. Here, we created a genetic mouse model of PIK3CA-related capillary venous malformations that replicates patient phenotypes. We showed that these malformations only partially signal through AKT proteins. We compared the efficacy of different drugs, including rapamycin, a mTORC1 inhibitor, miransertib, an AKT inhibitor and alpelisib, a PI3Kα inhibitor at improving the lesions seen in the mouse model. We demonstrated the effectiveness of alpelisib in preventing vascular malformations' occurrence, improving the already established ones, and prolonging survival. Considering these findings, we were authorized to treat 25 patients with alpelisib, including 7 children displaying PIK3CA (n = 16) or TEK (n = 9)-related capillary venous malformations resistant to usual therapies including sirolimus, debulking surgical procedures or percutaneous sclerotherapies. We assessed the volume of vascular malformations using magnetic resonance imaging (MRI) for each patient. Alpelisib demonstrated improvement in all 25 patients. Vascular malformations previously considered intractable were reduced and clinical symptoms were attenuated. MRI showed a decrease of 33.4% and 27.8% in the median volume of PIK3CA and TEK malformations respectively, over 6 months on alpelisib. In conclusion, this study supports PI3Kα inhibition as a promising therapeutic strategy in patients with PIK3CA or TEK-related capillary venous malformations.

Cerebral cavernous malformations - An overview on genetics, clinical aspects and therapeutic strategies

Cerebral cavernous malformations (CCMs) are abnormally packed blood vessels lined with endothelial cells, that do not exhibit intervening tight junctions, lack muscular and elastic layers and are usually surrounded by hemosiderin and gliosis. CCMs may be sporadic or familial autosomal dominant (FCCMs) caused by loss of function mutations in CCM1 (KRIT1), CCM2 (MGC4607), and CCM3 (PDCD10) genes. In the FCCMs, patients have multiple CCMs, different family members are affected, and developmental venous anomalies are absent. CCMs may be asymptomatic or may manifest with focal neurological deficits with or without associated hemorrhage andseizures. Recent studies identify a digenic "triple-hit" mechanism involving the aquisition of three distinct genetic mutations that culminate in phosphatidylinositol-3-kinase (PIK3CA) gain of function, as the basis for rapidly growing and clinically symptomatic CCMs. The pathophysiology of CCMs involves signaling aberrations in the neurovascular unit, including proliferative dysangiogenesis, blood-brain barrier hyperpermeability, inflammation and immune mediated processes, anticoagulant vascular domain, and gut microbiome-driven mechanisms. Clinical trials are investigating potential therapies, magnetic resonance imaging and plasma biomarkers for hemorrhage and CCMs-related epilepsy, as well as different techniques of neuronavigation and neurosonology to guide surgery in order to minimize post-operatory morbidity and mortality. This review addresses the recent data about the natural history, genetics, neuroimaging and therapeutic approaches for CCMs.

Exploring New Drug Repurposing Opportunities for MEK Inhibitors in RASopathies: A Comprehensive Review of Safety, Efficacy, and Future Perspectives of Trametinib and Selumetinib

The RASopathies are a group of syndromes caused by genetic variants that affect the RAS-MAPK signaling pathway, which is essential for cell response to diverse stimuli. These variants functionally converge towards the overactivation of the pathway, leading to various constitutional and mosaic conditions. These syndromes show overlapping though distinct clinical presentations and share congenital heart defects, hypertrophic cardiomyopathy (HCM), and lymphatic dysplasia as major clinical features, with highly variable prevalence and severity. Available treatments have mainly been directed to target the symptoms. However, repurposing MEK inhibitors (MEKis), which were originally developed for cancer treatment, to target evolutive aspects occurring in these disorders is a promising option. Animal models have shown encouraging results in treating various RASopathy manifestations, including HCM and lymphatic abnormalities. Clinical reports have also provided first evidence supporting the effectiveness of MEKi, especially trametinib, in treating life-threatening conditions associated with these disorders. Nevertheless, despite notable improvements, there are adverse events that occur, necessitating careful monitoring. Moreover, there is evidence indicating that multiple pathways can contribute to these disorders, indicating a current need to more accurate understand of the underlying mechanism of the disease to apply an effective targeted therapy. In conclusion, while MEKi holds promise in managing life-threatening complications of RASopathies, dedicated clinical trials are required to establish standardized treatment protocols tailored to take into account the individual needs of each patient and favor a personalized treatment.

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.

Changes in cell morphology and function induced by the NRAS Q61R mutation in lymphatic endothelial cells

Recently, a low-level somatic mutation in the NRAS gene (c.182 A > G, Q61R) was identified in various specimens from patients with kaposiform lymphangiomatosis. However, it is unknown how these low-frequency mutated cells can affect the characterization and surrounding environment of their lesions. To understand the pathogenesis and association of these gene abnormalities, we established NRASQ61R mutated lymphatic endothelial cells transfected with lentivirus vector and undertook morphological and functional characterization, protein expression profiling, and metabolome analysis. NRASQ61R human dermal lymphatic endothelial cells showed poor tube formation, a low proliferation rate, and high migration ability, with an increase in the ratio of mutated cells. An analysis of signaling pathways showed inactivation of the PIK3/AKT/mTOR pathway and hyperactivation of the RAS/MAPK/ERK pathway, which was improved by MAPK kinase (MEK) inhibitor treatment. This study shows the theoretical circumstances induced in vitro by NRASQ61R-mutated cells in the affected lesions of kaposiform lymphangiomatosis patients.

Targeted treatment in complex lymphatic anomaly: a case of synergistic efficacy of trametinib and sirolimus

Repurposing anticancer drugs to vascular malformations has significantly improved patient outcomes. Complex Lymphatic Anomalies (CLA) are part of the spectrum of lymphatic malformations (LMs) that share similar oncogenic mutations to cancer. We report the case of a young patient with highly symptomatic CLA who was initially treated with sirolimus, due to the frequent involvement of the PI3K-AKT-mTOR pathway in CLA pathogenesis. Despite an initial reduction in symptoms, sirolimus progressively lost its effectiveness. After an unsuccessful attempt with trametinib alone, sirolimus was added to trametinib and resulted in a significant, rapid and sustained improvement in symptoms. This suggests that, contrary to current dogmas, combination therapy using sub-therapeutic doses targeting both the PI3K and RAS pathways retains efficacy without generating the toxicity known for combination therapies, and is beneficial in the management of CLAs and potentially other vascular anomalies.

Congenital Vascular Malformations in Children: From Historical Perspective to a Multidisciplinary Approach in the Modern Era-A Comprehensive Review

Congenital vascular malformations (CVMs) are the result of an aberrant development during embryogenesis. Although these lesions are present at birth, they are not always visible yet. Once symptomatic, patients suffer from pain, bleeding, ulcers, infections or lymphatic leakage, depending on the subtype of vessels involved. Treatment includes conservative management, surgery, sclerotherapy, embolization and pharmacological therapy. The clinical presentation varies widely and treatment can be challenging due to the rarity of the disease and potential difficulties of treatment. This review gives an overview of the historical developments in diagnosis and classification and exposes the key elements of innovations in the past decades on the identification of genetic mutations and personalized treatment. These advances in the field and a multidisciplinary approach are highly valuable in the optimization of clinical care aimed at both curing or stabilizing the CVM and pursuing physical and psychosocial wellbeing.

Real-World Data on the Use of Sirolimus in Asian Children with Vascular Malformations

OBJECTIVES

The management of vascular malformations is complex and challenging. This study aimed to explore efficacy, plasma trough concentrations of sirolimus, post-withdrawal conditions, and adverse reactions of sirolimus in treating complex vascular malformations.

METHODS

In our center, we analyzed vascular malformations treated with sirolimus (and corticosteroid) from August 2017 to June 2021. Meanwhile, we reviewed the medical records, the efficacy, side effects, and laboratory tests. Patients who had stopped taking sirolimus were followed up by telephone.

RESULTS

A total of 25 patients with complicated vascular malformations in our center, including 7 females and 18 males aged 4 months to 15 years, were enrolled. In all, 19 patients (76.0%) responded to sirolimus, and the plasma concentration of sirolimus fluctuated between 0.97 and 27.15 ng/ml. In all, 24 patients (96.0%) were in follow-up. A total of 15 patients (62.5%) stopped taking sirolimus during follow-up, and 2 patients (13.3%) discontinued the sirolimus due to side effects. A total of 3 patients (20.0%) restarted sirolimus treatment.

CONCLUSION

Starting dose of 1.5-2 mg/m2 sirolimus is effective and safe in vascular malformation treatment. The best treatment regimen and discontinuation indications needed more investigation. Most should be done about targeted therapy to improve effectiveness and reduce side effects.

Sirolimus for Pediatric Cervicofacial Lymphatic Malformation: A Systematic Review and Meta-Analysis

OBJECTIVE

This study is a systematic review and meta-analysis of the efficacy and safety of sirolimus in the management of pediatric cervicofacial lymphatic malformations (LMs).

DATA SOURCES

EMBASE, Medline, Scopus, and Cochrane databases were searched, along with the reference list of all included articles.

REVIEW METHODS

The study protocol was registered with PROSPERO and a systematic literature search strategy was designed and conducted with the aid of a medical librarian. All studies including case reports were included, with pooled analysis of raw data. A meta-analysis was conducted of magnetic resonance imaging (MRI), clinical, and airway outcomes.

RESULTS

Thirteen case series and five individual case reports were included. Meta-analysis showed 78% (95% CI 57%-94%) of 62 patients had a reduction in LM volume, on MRI criteria, by 20% or more, and 32% (95% CI 11%-57%) had a reduction of 50% or more. Further meta-analysis showed 97% (95% CI 88%-100%) of 78 patients reported some clinical improvement on sirolimus. Sirolimus may be of particular value in management of airway LMs; out of 27 tracheostomy-dependent patients, meta-analysis showed 33% (95% CI 1%-78%) were decannulated after starting sirolimus. Individual patient meta-analysis on 24 individuals showed a statistically significant better response to sirolimus when initiated under the age of 2 years.

CONCLUSION

This review and meta-analysis support the efficacy of sirolimus in pediatric LMs of the head, neck, and airway. A large multi-center trial is needed to further explore its role and limitations. Laryngoscope, 134:2038-2047, 2024.

Interdisciplinary Management of Vascular Anomalies in the Head and Neck

Vascular anomalies in the head and neck area are usually rare diseases and pose a particular diagnostic and therapeutic challenge. They are divided into vascular tumours and vascular malformations. A distinction is made between benign tumours, such as infantile haemangioma, and rare malignant tumours, such as angiosarcoma. Vascular malformations are categorised as simple malformations, mixed malformations, large vessel anomalies and those associated with other anomalies. Treatment is interdisciplinary and various modalities are available. These include clinical observation, sclerotherapy, embolisation, ablative and coagulating procedures, surgical resection and systemic drug therapy. Treatment is challenging, as vascular anomalies in the head and neck region practically always affect function and aesthetics. A better understanding of the genetic and molecular biological basis of vascular anomalies has recently led to clinical research into targeted drug therapies. This article provides an up-to-date overview of the diagnosis, clinic and treatment of vascular anomalies in the head and neck region.

Central conducting lymphatic anomaly: from bench to bedside

Central conducting lymphatic anomaly (CCLA) is a complex lymphatic anomaly characterized by abnormalities of the central lymphatics and may present with nonimmune fetal hydrops, chylothorax, chylous ascites, or lymphedema. CCLA has historically been difficult to diagnose and treat; however, recent advances in imaging, such as dynamic contrast magnetic resonance lymphangiography, and in genomics, such as deep sequencing and utilization of cell-free DNA, have improved diagnosis and refined both genotype and phenotype. Furthermore, in vitro and in vivo models have confirmed genetic causes of CCLA, defined the underlying pathogenesis, and facilitated personalized medicine to improve outcomes. Basic, translational, and clinical science are essential for a bedside-to-bench and back approach for CCLA.

Surgical Management of Vascular Malformations of the Upper Extremity: A 12-Year Retrospective Cohort Study

INTRODUCTION

Vascular malformations (VMs) typically appear at birth and grow commensurately with patients. They can vary broadly in vessel type and tissue involvement, and upper extremity (UE) VMs can pose unique functional and aesthetic challenges in children. Given the advent of operative and nonoperative technologies like sclerotherapy and medications, a contemporary review of the surgical management of UE VMs is warranted.

METHODS

We performed a retrospective review of all patients who had surgical management of VMs from 2010 to 2021 at The Children's Hospital of Philadelphia. Demographics, lesion characteristics, treatment (including preceding nonsurgical therapies), complications, and final outcomes were recorded. Operative notes were reviewed for date of operation, depth of excision, type of closure, and current procedural terminology code.

RESULTS

Sixty-seven patients with 88 procedures were studied. Average patient age was 5.8 years, with 64% White and 67% male. Venous (34%) and lymphatic (19%) malformations were most common, and anatomic locations were most frequently on the hand (33%) and forearm (25%). The average lesion diameter was 4.2 cm, although this varied by location (eg, 2.9 cm, hand; 11.1 cm, chest wall). Fifty-eight patients (87%) underwent surgical excision as their index procedure, and 9 had sclerotherapy before surgery. Thirty-nine patients (60%) had subcutaneous excisions, and the remainder required subfascial or intramuscular excisions. Nearly all excisions were closed primarily (97%). Of the 53 patients with documented follow-up, 32 patients (60%) had complete resolution of their lesion as of their final visit. Thirty of these 32 patients with no clinical evidence of residual VM had only 1 surgery for excision.

CONCLUSION

Upper extremity VMs were composed of diverse conditions with varying vessel types, size, depth, and anatomic sites. Surgical excision of VMs of the UE was safe and effective. A majority of VMs were fully excised after 1 procedure and frequently closed primarily with relatively low complication rates. Future work should investigate decision-making and outcomes of all treatment options of VMs of the UE for optimal functionality and aesthetics.

Sirolimus experience in adult patients with vascular malformations

AIM

Sirolimus, a mammalian target of rapamycin inhibitor, inhibits cell growth and proliferation by controlling ribosome biogenesis and protein synthesis in vascular anomalies and cancers. However, most sirolimus studies on vascular anomalies were conducted in the pediatric population, with limited data in adults. In this study, we assessed the effectiveness and safety of sirolimus in adult patients with vascular malformation, a subtype of vascular anomaly.

METHODS

We conducted a retrospective analysis of adult vascular malformation patients aged over 16, treated at Hacettepe University Cancer Institute from January 2013 to September 2022. Patient demographics and clinical characteristics were recorded. The primary outcome was the efficacy of sirolimus evaluated by response and disease control rates. The disease control rate was defined as the cumulative percentage of complete or partial responses, along with stable disease. The secondary endpoint was toxicity and safety.

RESULTS

38 patients with a median age of 21 (IQR: 18-33) were recruited. Prior to sirolimus treatment, 57.9% of patients had undergone other therapeutic interventions, predominantly sclerotherapy and surgery. The median follow-up time during sirolimus treatment was 18.5 (IQR: 11.3-74.5) months. The disease control rate was 92.1% (35/38). Head-neck localization was associated with better response rates (p = .001). Sirolimus was generally well tolerated and grade 1 or 2 oral mucositis (n = 4) and skin rash (n = 3) were the most common side effects.

CONCLUSION

In this study, we found sirolimus was efficacious and well tolerated in adult patients with vascular malformation.

Psoralen: a narrative review of current and future therapeutic uses

Psoralen is a family of naturally occurring photoactive compounds found in plants that acquire potential cytotoxicity when activated by specific frequencies of electromagnetic waves. Psoralens penetrate the phospholipid cellular membranes and insert themselves between the pyrimidines of deoxyribonucleic acid (DNA). Psoralens are initially biologically inert and acquire photoreactivity when exposed to certain classes of electromagnetic radiation, such as ultraviolet light. Once activated, psoralens form mono- and di-adducts with DNA, leading to marked cell apoptosis. This apoptotic effect is more pronounced in tumor cells due to their high rate of cell division. Moreover, photoactivated psoralen can inhibit tyrosine kinase signaling and influence the immunogenic properties of cells. Thus, the cytotoxicity of photoactivated psoralen holds promising clinical applications from its immunogenic properties to potential anti-cancer treatments. This narrative review aims to provide an overview of the current understanding and research on psoralen and to explore its potential future pharmacotherapeutic benefits in specific diseases.

Combined surgery and sclerotherapy for 13 years: a case report of a patient with CLOVES

Congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and skeletal anomalies (CLOVES) constitute a rare overgrowth disorder resulting from a mosaic function-acquiring mutation in the PIK3CA gene. Targeted drugs for the PI3K-AKT signaling pathway remain under clinical trial and surgery is commonly used to meet both aesthetic and functional requirements for CLOVES patients. We report here the course and experience of a male patient treated at our institution for up to 13 years. The course of treatment consisted of nine anhydrous ethanol sclerotherapy procedures and two segmental trunk mass resections. After undergoing sequential treatment, the patient experienced improved thoracic deformity and scoliosis, enabling him to grow and develop normally.

Successful outcome with oral sirolimus treatment for complicated lymphatic malformations: a retrospective multicenter cohort study

Purpose

Sirolimus has emerged as a safe and effective treatment for complicated lymphatic malformations (LMs). We aim to prove the effectiveness and safety of sirolimus as a therapeutic option for patients with complicated LMs.

Methods

Fifty-eight patients with complicated LMs treated with sirolimus for at least 6 months at multicenter between July 2018 and January 2023 were enrolled. All patients were administered oral sirolimus starting at 0.8 mg/m2 every 12 hours, with target serum concentration levels of 8-15 ng/mL. Evaluation for clinical symptoms and LMs volume on MRI were reviewed to assess treatment response and toxicities. Evaluation of disease response was divided into 3 values: complete response, partial response (significant, moderate, and modest), and progressive disease.

Results

The median age at the initiation of sirolimus treatment was 6.0 years (range, 1 month-26.7 years). The median duration of treatment was 2.0 years (range, 6 months-4.4 years). The most common lesions were head and neck (25 of 58, 43.1%). Forty-six patients (79.3%) demonstrated a reduction in LMs volume on MRI or improvement of clinical symptoms including 2 complete responses. The young age group and the patients who underwent few prior therapies showed better responses. None of the patients had toxicities attributable to sirolimus with a Common Terminology Criteria for Adverse Events grade of ≥3.

Conclusion

Oral sirolimus treatment brought a successful outcome without severe adverse effects. It could be the first-line therapy, especially for the young age group of complicated LMs, and an additional option for refractory lesions that did not respond to conventional treatment.

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.

Medical Management and Therapeutic Updates on Vascular Anomalies of the Head and Neck: Part 2

Discovery of inherited and somatic genetic mutations, along with advancements in clinical and scientific research, has improved understanding of vascular anomalies and changed the treatment paradigm. With aim of minimizing need for invasive procedures and improving disease outcomes, molecularly targeted medications and anti-angiogenesis agents have become important as both adjuncts to surgery, and increasingly, as the primary treatment of vascular anomalies. This article highlights the commonly used and emerging therapeutic medications for non-malignant vascular tumors and vascular malformations in addition to medical management of associated hematologic abnormalities.

Medical Therapeutics for the Treatment of Vascular Anomalies: Part 3

The discovery of inherited and somatic genetic mutations, along with advancements in clinical and scientific research, has improved the understanding of vascular anomalies and changed the treatment paradigm. With the aim of minimizing the need for invasive procedures and improving disease outcomes, molecularly targeted medications and anti-angiogenesis agents have become important as both adjuncts to surgery, and increasingly, as the primary treatment of vascular anomalies. This article highlights the commonly used and emerging therapeutic medications for nonmalignant vascular tumors and vascular malformations.

Successful Management of Retropharyngeal Lymphangioma with Stridor Using Sirolimus: A Case Report

Lymphatic malformations (LMs) are one of the congenital malformations of the lymphatic system in the body. The patient usually presents with head and neck swelling, airway compression, and/or airway obstruction. The diagnosis of retropharyngeal LMs can be challenging due to their rare occurrence. We report a case of a five-month-old boy diagnosed with retropharyngeal LMs. He presented with a three-day history of fever, cough, and stridor and was initially treated for acute bronchiolitis. A lateral neck radiograph revealed prevertebral widening, suggesting retropharyngeal collection. The patient's condition worsened, requiring intubation in the operating room and proceeding with aspirations and drainage. However, the symptoms recurred after a few days, necessitating re-intubation, repeated aspirations and drainage procedures. The patient was intubated, and the neck's magnetic resonance imaging (MRI) confirmed retropharyngeal LMs. An elective tracheostomy was performed and was treated with sirolimus. The patient had a successful tracheostomy decannulation and showed no recurrence during follow-up.

Medical Management of Nonmalignant Vascular Tumors of the Head and Neck: Part 1

Vascular anomalies, broadly classified as nonmalignant tumors and malformations, consist of a multitude of disorders that have a wide range of symptoms and complications as well as overlapping clinical, radiologic, and histologic findings. Although usually difficult, distinguishing between nonmalignant vascular tumors and malformations, as well as the precise diagnosis within these distinctions, is critical because prognosis, therapy, and chronicity of care vary greatly. In contrast to normal endothelial turnover in vascular malformations, vascular tumors are characterized by the abnormal proliferation of endothelial cells and aberrant blood vessels.

Updates in Genetic Testing for Head and Neck Vascular Anomalies

Vascular anomalies include benign or malignant tumors or benign malformations of the arteries, veins, capillaries, or lymphatic vasculature. The genetic etiology of the lesion is essential to define the lesion and can help navigate choice of therapy. . In the United States, about 1.2% of the population has a vascular anomaly, which may be underestimating the true prevalence as genetic testing for these conditions continues to evolve.

Factors affecting the ability of patients with complex vascular anomalies to navigate the healthcare system

BACKGROUND

Vascular anomalies (VAs) are rare congenital disorders that can cause pain, disfigurement, coagulopathy, asymmetric growth, and disability. Patients with complex VAs experience multiple barriers to accessing expert care. It is imperative to understand which factors support these patients' ability to navigate the healthcare system.

RESULTS

We surveyed adult patients with VAs using previously validated measures, recruiting participants from five patient advocacy groups and multidisciplinary VA clinics. The primary outcome was self-reported ability to access needed medical care, using the "Navigating the Healthcare System" subscale of the Health Literacy Questionnaire. We evaluated factors associated with the ability to navigate the healthcare system using multivariate linear regression (n = 136). We also performed an exploratory model that included the primary care doctor's knowledge of VAs for the subset of participants with a primary care doctor (n = 114). Participants were predominantly women (n = 90, 66%), White and non-Hispanic (n = 109, 73%), and college-educated (n = 101, 73%). Most participants had PIK3CA-Related Overgrowth Spectrum (n = 107, 78%). Most participants reported that navigating the healthcare system was "sometimes" or "usually difficult" (mean score 16.4/30, standard deviation 5.6). In multivariate linear regression, ability to navigate the healthcare system was associated positively with quality of information exchange (β = 0.38, 95% Confidence Interval (CI) 0.22 to 0.55, p <.001) and whether patients had VA specialists (β = 2.31, 95% CI 0.35 to 4.28, p =.021), but not associated with patient self-advocacy, anxiety, education, age, race and ethnicity, gender, or having a primary care doctor. In exploratory analysis of participants with primary care doctors, ability to navigate the healthcare system was positively associated with quality of information exchange (β = 0.27, 95% CI 0.09 to 0.45, p =.004), having a VA specialist (β = 2.31, 95% CI 0.22 to 4.39, p =.031), and primary care doctors' VA knowledge (β = 0.27, 95% CI 0.04 to 0.50, p =.023).

CONCLUSION

Patients with VAs struggle to navigate the healthcare system. High-quality information from clinicians and more knowledgeable primary care doctors might help patients to access needed care. Relying on patient self-advocacy is insufficient. Future efforts should focus on patient-directed and clinician-directed educational interventions. Additionally, future work should assess the structural barriers that impede healthcare access for these patients.

Short-term outcomes of combined therapy with sirolimus and interferon-alpha 2b for advanced hepatic epithelioid hemangioendothelioma

Background

Hepatic epithelioid hemangioendothelioma (EHE) is an extremely rare tumor, and no standard therapy has been established yet.

Objectives

The aim of this study was to investigate the short-term results of combined therapy with sirolimus and interferon-alpha 2b (IFN-a 2b) (SI therapy).

Methods

From January 2022 to April 2023, 40 patients histologically diagnosed with hepatic EHE and progressive disease received SI therapy. All patients were regularly evaluated for the safety and efficacy of the SI therapy. Patients who received SI therapy for <3 months without a tumor status evaluation after treatment were excluded.

Results

Twenty-nine patients with hepatic EHE were included in this study. The Eastern Cooperative Oncology Group (ECOG) performance status was 0 in 19 (65.5%) patients and 1 in 10 (34.5%) patients. The median duration of the SI therapy was 8 months (range, 3-15 months). Twenty-three (79.3%) patients showed a decrease in tumor size, including 11 (37.9%) patients who achieved a partial response and one (3.4%) who achieved a complete response; the objective response rate was 41.4%. Stable disease was observed in 13 (44.8%) patients, with a disease control rate of 86.2%. Adverse events (AES) were observed in 18 patients, including leukopenia (31.0%), oral ulcers (13.8%), and liver injury (10.3%). No severe (grade ⩾ 3) AEs were recorded, and SI therapy was not interrupted for any patient due to AEs.

Conclusion

Sirolimus and IFN-a 2b may have synergistic effects in the treatment of hepatic EHE. SI therapy is a safe and effective treatment for hepatic EHE patients with good ECOG performance status.

Infectious complications of vascular anomalies treated with sirolimus: A systematic review

BACKGROUND AND OBJECTIVES

Initially developed as immunosuppressive agents, mammalian target of rapamycin (mTOR) inhibitors are currently used widely in the management of vascular malformations and tumors. The incidence of infectious complications in the vascular anomalies (VA) population is not well defined. The goal of this systematic review was to better define the types and severity of reported infectious complications in patients with VAs treated with mTOR inhibition.

METHODS

This was a systematic review conducted following PRISMA guidelines evaluating all research articles focused on infectious complications in patients with VAs treated with sirolimus or everolimus. Thirty articles including 1182 total patients and 316 infections (in 291 unique patients) were ultimately included.

RESULTS

The majority of infections were viral upper respiratory (n = 137, 54%), followed by pneumonia (n = 53, 20%), and cutaneous infections (n = 20, 8%). There were six total infection-related fatalities, which all occurred in patients younger than 2 years. Two cases of Pneumocystis jirovecii pneumonia (PJP) were reported. These were infants with kaposiform hemangioendothelioma (KHE) who were also treated with steroids and did not receive PJP prophylaxis. Almost one-third (n = 96, 32%) of infectious complications were graded 3-4 according to Common Terminology Criteria for Adverse Events (CTCAE) criteria. Details of patient age, subtype of VA, and timing of infection were lacking from many reports.

CONCLUSIONS

Most infectious complications reported in patients with VA on mTOR inhibitors were viral respiratory infections and non-severe. Bacteremia, infectious fatalities, and PJP are exceedingly rare. Future studies are needed to clarify the spectrum of infectious risks in VA patients and to provide guidance for infection prevention.

Microcystic lymphatic malformations in Turner syndrome are due to somatic mosaicism of PIK3CA

Turner syndrome (45,X) is caused by a complete or partial absence of a single X chromosome. Vascular malformations occur due to abnormal development of blood and/or lymphatic vessels. They arise from either somatic or germline pathogenic variants in the genes regulating growth and apoptosis of vascular channels. Aortic abnormalities are a common, known vascular anomaly of Turner syndrome. However, previous studies have described other vascular malformations as a rare feature of Turner syndrome and suggested that vascular abnormalities in individuals with Turner syndrome may be more generalized. In this study, we describe two individuals with co-occurrence of Turner syndrome and vascular malformations with a lymphatic component. In these individuals, genetic testing of the lesional tissue revealed a somatic pathogenic variant in PIK3CA-a known and common cause of lymphatic malformations. Based on this finding, we conclude that the vascular malformations presented here and likely those previously in the literature are not a rare part of the clinical spectrum of Turner syndrome, but rather a separate clinical entity that may or may not co-occur in individuals with Turner syndrome.

SH2 domain protein E and ABL signaling regulate blood vessel size

Blood vessels in different vascular beds vary in size, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vessel size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow, eventually leading to the DA collapse. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA size in she mutants correlated with an increased endothelial expression of claudin 5a (cldn5a), which encodes a protein enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates vessel and lumen size during vascular tubulogenesis.

Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L-lactic-co-glycolic acid-based substrate for cardiovascular device application

Biodegradable drug-eluting stents (DESs) are gaining importance owing to their attractive features, such as complete drug release to the target site. Magnesium (Mg) alloys are promising materials for future biodegradable DESs. However, there are few explorations using biodegradable Mg for cardiovascular stent application. In this present study, sirolimus-loaded poly D, L-lactic-co-glycolic acid (PLGA)-coated/ sirolimus-fixed/AZ91 Mg alloy-based substrate was developed via a layer-by-layer approach for cardiovascular stent application. The AZ91 Mg alloy was prepared through the squeeze casting technique. The casted AZ91 Mg alloy (Mg) was alkali-treated to provide macroporous networks to hold the sirolimus and PLGA layers. The systematic characterization was investigated via electrochemical, optical, physicochemical, and in-vitro biological characteristics. The presence of the Mg17 Al12 phase in the Mg sample was found in the x-ray diffraction system (XRD) spectrum which influences the corrosion behavior of the developed substrate. The alkali treatment increases the substrate's hydrophilicity which was confirmed through static contact angle measurement. The anti-corrosion characteristic of casted-AZ91 Mg alloy (Mg) was slightly less than the sirolimus-loaded PLGA-coated alkali-treated AZ91 Mg alloy (Mg/Na/S/P) substrate. However, dissolution rates for both substrates were found to be controlled at cell culture conditions. Radiographic densities of AZ91 Mg alloy substrates (Mg, Mg/Na, and Mg/Na/S/P) were measured to be 0.795 ± 0.015, 0.742 ± 0.01, and 0.712 ± 0.017, respectively. The star-shaped structure of 12% sirolimus/PLGA ensures the bioavailability of the drugs. Sirolimus release kinetic was fitted up to 80% with the "Higuchi model" for Mg samples, whereas Mg/Na/S/P showed 45% fitting with a zero-order mechanism. The Mg/Na/S/P substrate showed a 70% antithrombotic effect compared to control. Further, alkali treatment enhances the antibacterial characteristic of AZ91 Mg alloy. Also, the alkali-treated sirolimus-loaded substrates (Mg/Na/S and Mg/Na/S/P) inhibit the valvular interstitial cell's growth significantly in in-vitro. Hence, the results imply that sirolimus-loaded PLGA-coated AZ91 Mg alloy-based substrate can be a potential candidate for cardiovascular stent application.

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.

Emerging Therapeutic Options for Refractory Pulmonary Sarcoidosis: The Evidence and Proposed Mechanisms of Action

Sarcoidosis is a systemic disease with heterogenous clinical phenotypes characterized by non-necrotizing granuloma formation in affected organs. Most disease either remits spontaneously or responds to corticosteroids and second-line disease-modifying therapies. These medications are associated with numerous toxicities that can significantly impact patient quality-of-life and often limit their long-term use. Additionally, a minority of patients experience chronic, progressive disease that proves refractory to standard treatments. To date, there are limited data to guide the selection of alternative third-line medications for these patients. This review will outline the pathobiological rationale behind current and emerging therapeutic agents for refractory or drug-intolerant sarcoidosis and summarize the existing clinical evidence in support of their use.

Approach to clinically significant vascular anomalies in children

Vascular anomalies consist of tumours or malformations made up of abnormal growth or collections of blood vessels that can result in functional or cosmetic problems. While many vascular anomalies are present at birth, some do not appear until later in life, making diagnosis more challenging. Although many vascular anomalies are benign, some are associated with serious complications and may involve multiple organ systems. This article highlights the important features of clinically significant vascular anomalies to help physicians promptly identify and refer these cases to a specialised multidisciplinary team for evaluation and management. The discussion includes the various presenting complaints of vascular anomalies in children, namely, rapidly growing birthmarks, painful lesions, seizures/neurological manifestations, bleeding diathesis, cardiac/airway abnormalities and part of an overgrowth syndrome.

Alpelisib for treatment of patients with PIK3CA-related overgrowth spectrum (PROS)

PURPOSE

PIK3CA-related overgrowth spectrum (PROS) encompasses several rare conditions resulting from activating variants in PIK3CA. Alpelisib, a PI3Kα-selective inhibitor, targets the underlying etiology of PROS, offering a novel therapeutic approach to current management strategies. This study evaluated the safety and efficacy of alpelisib in pediatric and adult patients with PROS.

METHODS

EPIK-P1 (NCT04285723) was a non-interventional, retrospective chart review of 57 patients with PROS (≥2 years) treated with alpelisib through compassionate use. Patients had severe/life-threatening PROS-related conditions and confirmed PIK3CA pathogenic variant. The primary end point assessed patient response to treatment at Week 24 (6 months).

RESULTS

Twenty-four weeks (6 months) after treatment initiation, 12 of 32 (37.5%) patients with complete case records included in the analysis of the primary end point experienced a ≥20% reduction in target lesion(s) volume. Additional clinical benefit independent from lesion volume reduction was observed across the full study population. Adverse events (AEs) and treatment-related AEs were experienced by 82.5% (47/57) and 38.6% (22/57) of patients, respectively; the most common treatment-related AEs were hyperglycemia (12.3%) and aphthous ulcer (10.5%). No deaths occurred.

CONCLUSION

EPIK-P1 provides real-world evidence of alpelisib effectiveness and safety in patients with PROS and confirms PI3Kα as a valid therapeutic target for PROS symptom management.

Treatment of severe Kaposiform lymphangiomatosis positive for NRAS mutation by MEK inhibition

BACKGROUND

Kaposiform lymphangiomatosis (KLA) is a complex lymphatic anomaly involving most commonly the mediastinum, lung, skin and bones with few effective treatments. In recent years, RAS-MAPK pathway mutations were shown to underlie the pathogenesis of several complex lymphatic anomalies. Specifically, an activating NRAS mutation (p.Q61R) was found in the majority of KLA patients. Recent reports demonstrated promising results of treatment with the MEK inhibitor, Trametinib, in patients with complex lymphatic anomalies harboring gain of function mutations in ARAF and SOS1, as well as loss of function mutation in the CBL gene, a negative regulator of the RAS-MAPK pathway. We present a 9-year-old child with a severe case of KLA harboring the typical NRAS (p.Q61R) mutation detected by plasma-derived cell free DNA, responsive to trametinib therapy.

METHODS

The NRAS somatic mutation was detected from plasma cfDNA using droplet digital PCR. Concurrent in-vitro studies of trametinib activity on mutant NRAS affected lymphatic endothelial cells were performed using a three-dimensional spheroid sprouting assay.

RESULTS

Trametinib treatment lead to resolution of lifelong thrombocytopenia, improvement of pulmonary function tests and wellbeing, as well as weaning from prolonged systemic steroid treatment. Concurrent studies of mutant NRAS-expressing cells showed enhanced lymphangiogenic capacity along with over activation of the RAS-MAPK and PI3K-AKT-mTOR pathways, both reversed by trametinib.

CONCLUSIONS

Trametinib treatment can substantially change the prognosis of patients with RAS pathway associated lymphatic anomalies.

IMPACT

This is the first description of successful trametinib treatment of a patient with KLA harboring the most characteristic NRAS p.Q61R mutation. Treatment can significantly change the prognosis of patients with RAS pathway-associated lymphatic anomalies. We devised an in vitro model of KLA enabling a reproducible method for the continued study of disease pathogenesis. Mutated NRAS p.Q61R cells demonstrated increased lymphangiogenic capacity.

Trametinib inhibits lymphatic vessel invasion of bone in a mouse model of Gorham-Stout disease

Objective

Gorham-Stout disease (GSD) is a rare lymphatic anomaly that can be caused by somatic activating mutations in KRAS. This discovery has led investigators to suggest that MEK inhibitors could be a novel treatment for GSD. However, the effect of MEK inhibitors on bone disease in animal models of GSD has not been investigated. We recently reported that Osx-tTA;TetO-Vegfc mice exhibit a phenotype that resembles GSD. Osx-tTA;TetO-Vegfc mice overexpress VEGF-C in bone, which stimulates the development of lymphatic vessels in bone and the gradual loss of cortical bone. The objective of this study was to characterize the effect of trametinib, an FDA-approved MEK1/2 inhibitor, on lymphangiogenesis and osteolysis in Osx-tTA;TetO-Vegfc mice.

Methods

Immunoblotting was performed to assess the effect of trametinib on VEGF-C-induced phosphorylation of ERK1/2, AKT, and S6 in primary human lymphatic endothelial cells (LECs). Prevention and intervention experiments were performed to determine the effect of trametinib on lymphangiogenesis and osteolysis in Osx-tTA;TetO-Vegfc mice.

Results

We found that trametinib blocked VEGF-C-induced phosphorylation of ERK1/2 in primary human LECs. We also found that trametinib prevented VEGF-C-induced lymphatic invasion of bone and cortical bone loss in Osx-tTA;TetO-Vegfc mice. Additionally, trametinib slowed the progression of disease in Osx-tTA;TetO-Vegfc mice with established disease. However, it did not reverse disease in Osx-tTA;TetO-Vegfc mice.

Conclusion

Our results show trametinib impacts bone disease in Osx-tTA;TetO-Vegfc mice. These findings further support the testing of MEK inhibitors in patients with GSD and other RAS pathway-driven complex lymphatic anomalies with bone involvement.

Clinical effectiveness and safety of sirolimus in pediatric patients with complex vascular anomalies: necessitating personalized and comprehensive approaches

Background

Managing complex vascular anomalies in pediatric care requires comprehensive approaches. Sirolimus, an mTOR inhibitor with immunosuppressive and anti-angiogenic properties, offers promise. We evaluated sirolimus's effectiveness and safety in pediatric patients with complex vascular anomalies at a tertiary children's hospital.

Methods

Our study included 20 patients, aged 1 month to 19 years, with diverse vascular anomalies resistant to conventional therapies or located in high-risk areas precluding surgery. The evaluation of response encompassed measuring the reduction in the size of the targeted vascular or lymphatic lesions as observed on radiologic imaging, along with considering improvements reported by the patients.

Results

Patients used sirolimus for a median of 2.1 years, ranging from 0.6-4.3 years. Results indicated that 60% of patients achieved complete or partial response (CR/PR), whereas 40% had stable disease (SD). Notably, no disease progression occurred. Lesion size assessment was complex, yet patients' self-reported improvements were considered. Three patients reinitiated sirolimus after discontinuation due to worsening lesions. Sirolimus treatment demonstrated good tolerability, with minor complications except for one case of Pneumocystis jiroveci pneumonia. Group comparisons based on response highlighted better outcomes in patients with vascular tumors (CR/PR group 58.0% vs. SD group 0.0%, P = 0.015) or localized measurable lesions (83.3% vs. 12.5%, P = 0.005).

Conclusion

Our study underscores sirolimus's potential for treating complex vascular anomalies in pediatric patients. Challenges associated with optimal treatment duration and concurrent interventions necessitate a comprehensive approach and genetic testing to optimize outcomes.