A prospective multicenter study of sirolimus for complicated vascular anomalies

Consensus statement for the diagnosis, treatment, and prognosis of kaposiform hemangioendothelioma

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that typically presents in infancy or early childhood. As awareness of KHE increases, it is imperative that the management of KHE be updated to reflect the latest evidence-based guidelines. The aim of this study was to integrate the literature and Chinese expert opinions to provide updated recommendations that will guide the diagnosis, treatment, and prognosis of patients with KHE. According to this consensus statement, 28 nationally peer-recognized experts in vascular anomalies and an expert in evidence-based medicine were assembled and formed three consensus subgroups. A series of key themes and questions were developed for each group, including recommendations for diagnosis, treatment, and prognosis. A systematic search was conducted for English-language articles published in PubMed and other relevant studies identified by the expert panel. A diagnosis of KHE necessitates the integration of clinical, imaging, and histologic features. The treatment of KHE should be tailored to the specific characteristics of each patient, including the size of the lesion, the presence of symptoms, the location, and the overall condition of the patient. In addition to focusing on the disease itself, it is also important to consider the complications of KHE and their impact on prognosis. The recommendations presented herein are intended to assist in the guidance of clinical practice and decision-making in patients with KHE, with the objective of improving patient outcomes.

Long-term effects of sirolimus treatment for slow-flow vascular malformations: Real-world evidence from the French observational multicentre SIROLO study

RATIONALE

Sirolimus is a treatment for slow-flow vascular malformations (SFVMs). However, the long-term management remains challenging.

OBJECTIVES

The SIROLO study assessed the long-term effects and real-life management of oral sirolimus for SFVMs by investigating data from 15 French tertiary centres for vascular anomalies.

METHODS

Participants were retrospectively included if they had a SFVM that was being/had been treated with sirolimus for at least 3 years in total. Data were collected on treatment goals when initiating sirolimus, investigator-reported efficacy, safety, dosages and treatment withdrawal.

RESULTS

The cohort involved 67 patients with various SFVM entities (mean [±SD] age 19.6 ± 12.5 years, 35 children, 52.2%). We found a heterogeneity of predefined treatment goals, the most frequent being cessation of pain. The investigators considered that sirolimus had persistent efficacy for bleeding, ulceration and pain but only slight efficacy for reducing volume. It was reported to be well-tolerated, although serious adverse events (mainly infections and also two ovarian cysts) were reported in 6 patients (9.0%) and required definitive sirolimus discontinuation for one. Overall, 11 patients (16.4%) had at least one temporary withdrawal period, leading to symptom recurrence and sirolimus resumption at a mean of 6.4 ± 9.6 months. The mean sirolimus concentration was 6.4 ± 3.7 ng/mL during the first 6 months and decreased over time (mean concentration during the last 6 months: 4.2 ± 3.2 ng/mL), probably to target the minimal efficient dosage. Eight patients (11.9%) switched to alpelisib because of insufficient efficacy of sirolimus.

CONCLUSIONS

This real-life study gives answers to frequent questions patients and parents ask before sirolimus initiation for SFVMs, such as persistence of efficacy over time, long-term side effects and time to recurrence in case of withdrawal.

Targeted Therapies for Slow-Flow Vascular Malformations

Advances in genetic sequencing technologies have enabled the identification of key activating somatic variants in cellular signalling pathways involved in the pathogenesis of vascular malformations. Given that these genetic variants are also implicated in the pathogenesis of several cancers, the repurposing of targeted therapies developed in oncology has been increasingly investigated for treating vascular malformations. This review provides an update on the current evidence for targeted therapies in slow-flow vascular malformations, particularly in the context of gain-of-function variants in the PI3K/AKT/mTOR pathway.

Global research trends and basis of venous/lymphatic malformations during 2003-2023: a bibliometric study over two decades

Introduction

Venous/lymphatic malformations (VM/LM) represent a group of vascular anomalies that share similarities in diagnosis, classification, management, and pathogenesis. Despite growing research interest, no comprehensive bibliometric analysis has been conducted to map the knowledge landscape and evolution of VM/LM studies.

Methods

We searched the Web of Science Core Collection database for VM/LM-related publications from January 2003 to December 2023. multiple analytical tools including VOSviewer, CiteSpace, and R package 'bibliometrix' were used to analyze publication trends, collaboration networks, and research hotspots.

Results

4,747 publications with 57,893 references were enrolled and analyzed. The number of publications is growing generally and erupted in 2019. The USA, China, and Japan are the top 3 countries in publication. The main study centers are scattered in the USA, Europe, China, and Japan. Fishman SJ published most. Vikkula M was cited most. Journal of Pediatric Surgery published and was cited most. The knowledge basis of VM/LM contains a wide range of concepts including classification/differential diagnosis, genetic causes, Sirolimus treatment, localized intravascular coagulopathy, and percutaneous treatment. The topic trend mainly changed after 2019 to genetic study and targeted therapy.

Discussion

This is the first bibliometric analysis of VM/LM research demonstrating the field's rapid growth and shifting research hotspots. Four key future directions emerged: molecular-level diagnosis and classification, precision targeted therapy, advanced sclerotherapy techniques, and artificial intelligence applications. International collaboration between countries and centers needs to be strengthen. These findings provide an objective foundation for future VM/LM investigations.

Sirolimus for kaposiform hemangioendothelioma: Potential mechanisms of action and resistance

Kaposiform hemangioendotheliomas (KHEs) are vascular tumors that are considered borderline or locally aggressive and may lead to lethal outcomes. Traditional therapies, such as surgery and embolization, may be insufficient or technically impossible for patients with KHE. Sirolimus (or rapamycin), a specific inhibitor of mechanistic target of rapamycin, has recently been demonstrated to be very useful in the treatment of KHEs. Here, we highlight recent substantial progress regarding the effects of sirolimus on KHEs and discuss the potential mechanisms of action of sirolimus in treating this disease. The prevention of platelet activation and inflammation, along with antiangiogenic effects, the inhibition of lymphangiogenesis, the attenuation of fibrosis, or a combination of all these effects, may be responsible for the therapeutic effects of sirolimus. In addition, the mechanism of sirolimus resistance in some KHE patients is discussed. Finally, we review the somatic mutations that have recently been identified in KEH lesions, and discuss the potential of novel therapeutic targets based on these further understandings of the cellular and molecular pathogenesis of KHE.

A phase 2 randomized, double-blind trial of ART-001, a selective PI3Kα inhibitor, for the treatment of slow-flow vascular malformations

BACKGROUND

In patients with slow-flow vascular malformations (SFVMs) including venous malformations (VM), lymphatic malformations (LM) or Klippel-Trenaunay Syndrome (KTS), somatic gain-of-function mutations in genes encoding phosphatidyl inositol 3-kinase alpha (PI3Kα, gene name PIK3CA) have been identified. A phase 2 study was conducted with the patients to assess the efficacy and safety of ART-001 (serabelisib), an orally available selective PI3Kα inhibitor.

METHODS

This is a multicenter, randomized, double-blind, proof-of-concept, phase 2 trial. Eligible participants were patients aged 2 years and older, diagnosed either with VM, LM or KTS. Participants were administered either 50 or 100 mg of ART-001 for 24 weeks. The primary endpoint was the response rate defined as the proportion of participants who achieved ≥ 20% reduction in lesion volume at week 24. Secondary endpoints include safety, pharmacokinetics, pain, and quality of life scores.

RESULTS

Thirty-five patients (median age: 14 years old; VM, n = 17, KTS, n = 13 and LM, n = 5) were randomly assigned and received treatment (50 mg, n = 17 and 100 mg, n = 18). ART-001 showed a response rate: 29.4% (95% confidence interval 10.3-56.0%) at 50 mg and 33.3% (13.3-59.0%) at 100 mg. Mean lesion volume reductions at 50 mg and 100 mg were - 2.3% (95% CI - 14.3 to 9.6%) and - 12.6% (- 25.3 to 0.06%), respectively. No drug-related serious adverse events were observed. Treatment-emergent adverse events were generally mild to moderate and transient. Pharmacokinetic profiles were similar between pediatric and adolescent/adult patients except for lower Ctrough levels in pediatric patients.

CONCLUSION

ART-001 was effective and well-tolerated in patients with SFVMs. These results support the further development of ART-001 in SFVMs and other PIK3CA-related overgrowth syndromes to confirm clinical benefits and long-term safety.

TRIAL REGISTRATION

 Japan Registry of Clinical Trial, jRCT2071210027. Registered May 25 2021, https://jrct.niph.go.jp/en-latest-detail/jRCT2071210027.

Clinical characteristics and risk factors for acute abdomen in patients with abdominal lymphatic malformations

OBJECTIVE

The diagnosis of abdominal lymphatic malformations (ALMs) is often overlooked in clinical practice. However, reports in the literature about ALMs are limited to case reports and series with small sample sizes. This study aimed to review our currently available data to describe the clinical characteristics of ALMs and evaluate the risk factors for acute abdomen caused by ALMs.

METHODS

We reviewed the records of patients with ALMs who were diagnosed between December 2008 and January 2023 in our institution. The associations between acute abdomen and ALMs were analyzed based on single-factor and multivariate logistic regression analyses.

RESULTS

This study included 345 patients with pathologically confirmed ALMs, with a slight female predominance of 1:1.4. Approximately 39.1% (135/345) of patients were asymptomatic, and 24.6% (85/345) presented with acute abdomen. Among the ALMs in the cohort, 42.6% (147/345) were retroperitoneal lymphatic malformations (LMs). The maximal lesion dimensions in patients with acute abdomen and nonacute abdomen were 10.0 cm and 7.8 cm, respectively, with no significant difference based on multivariate analyses. Children were more likely to develop acute abdomen than adults were (P = .002; odds ratio, 5.128; 95% confidence interval, 1.835-14.326). ALMs accompanying acute abdomen were more common for lesions involving the small intestinal mesentery (P = .023; odds ratio, 2.926; 95% confidence interval, 1.157-7.400).

CONCLUSIONS

ALMs are rare with an insidious onset, and retroperitoneal LMs are the most common ALMs, followed by jejunal mesenteric LMs. Our retrospective analysis suggested that young age and small intestinal mesenteric lymphatic malformation are independent risk factors for acute abdomen with ALMs.

Targeted medical therapies for vascular anomalies

The last 2 decades of genetic discovery in the field of vascular anomalies have brought targeted medical therapies to the forefront of care patients with vascular anomalies and have broadened the role of hematologists/oncologists in this field. Many vascular anomalies have now been identified to be driven by somatic gain-of-function variants in the PI3K/AKT/ mTOR and Ras/MAPK intracellular signaling pathways. This has led to the introduction of various antiangiogenic agents that inhibit these pathways. Knowledge of the indications for and the safe administration of these agents in patients with vascular anomalies is now a crucial part of training for hematologists/oncologists.

Clinical characteristics and managements of congenital hepatic hemangioma: a cohort study of 211 cases

BACKGROUND

Hepatic hemangiomas can be classified into three morphologic patterns: focal (congenital hepatic hemangiomas [CHHs]), multifocal, and diffuse. We aimed to identify the clinical characteristics of CHH and evaluate the changes in CHH management at our institution over the last 2 decades.

METHODS

This was a retrospective cohort study of children diagnosed with CHH who were managed at 8 investigation sites. The primary outcome was changes in CHH size in patients at the last follow-up. The primary exposure of interest was management modality in 2 study periods (2003-2012 versus 2013-2022).

RESULTS

Two hundred and eleven patients were analyzed. Four different subtypes of CHH were identified. Rapidly involuting CHH patients had complete involution/nearly complete involution, with a median age of 12.0 months. Noninvoluting CHH presented no change in CHH size. Partially involuting CHH patients presented with partial involution and had a stable tumor size at a median age of 16.0 months. Postnatally proliferating CHHs had an initial postnatal increase in CHH lesion size and underwent involution at a median age of 27.0 months. Further analysis revealed that management strategies for CHHs have shifted over time, with the proportion of patients receiving expectant management increasing from 35.4% before 2013 to 77.7% after 2013 (difference, 42.3%; 95% confidence interval 29.3-53.3%). The survival rate of patients with CHH was high (98.6%).

CONCLUSIONS

We documented 4 subtypes of CHHs. We found that expectant management strategies have increasingly replaced invasive interventions in patients with CHH over the past 2 decades.

RESEARCH REGISTRATION UNIQUE IDENTIFYING NUMBER (UIN)

We have already registered at Clinicaltrials.gov. The UIN number is NCT03331744.

Somatic RIT1 delins in arteriovenous malformations hyperactivate RAS-MAPK signaling amenable to MEK inhibition

Arteriovenous malformations (AVM) are benign vascular anomalies prone to pain, bleeding, and progressive growth. AVM are mainly caused by mosaic pathogenic variants of the RAS-MAPK pathway. However, a causative variant is not identified in all patients. Using ultra-deep sequencing, we identified novel somatic RIT1 delins variants in lesional tissue of three AVM patients. RIT1 encodes a RAS-like protein that can modulate RAS-MAPK signaling. We expressed RIT1 variants in HEK293T cells, which led to a strong increase in ERK1/2 phosphorylation. Endothelial-specific mosaic overexpression of RIT1 delins in zebrafish embryos induced AVM formation, highlighting their functional importance in vascular development. Both ERK1/2 hyperactivation in vitro and AVM formation in vivo could be suppressed by pharmacological MEK inhibition. Treatment with the MEK inhibitor trametinib led to a significant decrease in bleeding episodes and AVM size in one patient. Our findings implicate RIT1 in AVM formation and provide a rationale for clinical trials with targeted 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.

Non-Surgical Management of Recurrent Naso-Orbital Hemangiomas with Bevacizumab: A Case Report

In this case report, we describe a 21-year-old man with recurrent hemangiomas in his left eye socket and nasal cavity. Traditional surgeries were unsuccessful, so we used Bevacizumab, a drug that inhibits blood vessel growth. This approach significantly reduced the tumor size and stopped frequent nosebleeds. Over two years, the tumor remained controlled without major side effects, suggesting Bevacizumab as a promising non-surgical treatment for recurrent hemangiomas.

Management and Outcomes of Pediatric Lymphatic Malformations: A Systematic Review From the APSA Outcomes and Evidence-Based Practice Committee

BACKGROUND

Significant variation in management strategies for lymphatic malformations (LMs) in children persists. The goal of this systematic review is to summarize outcomes for medical therapy, sclerotherapy, and surgery, and to provide evidence-based recommendations regarding the treatment.

METHODS

Three questions regarding LM management were generated according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Publicly available databases were queried to identify articles published from January 1, 1990, to December 31, 2021. A consensus statement of recommendations was generated in response to each question.

RESULTS

The initial search identified 9326 abstracts, each reviewed by two authors. A total of 600 abstracts met selection criteria for full manuscript review with 202 subsequently utilized for extraction of data. Medical therapy, such as sirolimus, can be used as an adjunct with percutaneous treatments or surgery, or for extensive LM. Sclerotherapy can achieve partial or complete response in over 90% of patients and is most effective for macrocystic lesions. Depending on the size, extent, and location of the malformation, surgery can be considered.

CONCLUSION

Evidence supporting best practices for the safety and effectiveness of management for LMs is currently of moderate quality. Many patients benefit from multi-modal treatment determined by the extent and type of LM. A multidisciplinary approach is recommended to determine the optimal individualized treatment for each patient.

LEVEL OF EVIDENCE: 4

Therapeutic Drug Monitoring for Sirolimus in Children with Vascular Anomalies: What Can We Learn from a Retrospective Study

Objectives: Sirolimus (SRL), a mammalian target of rapamycin inhibitor, has been widely used to treat patients with vascular anomalies (VAs). The objectives of this study were to summarize the routine blood SRL monitoring data for VAs children, to investigate the factors contributing to the variable blood SRL concentrations and to evaluate the efficacy and safety of SRL therapy. Methods: VAs patients with routine blood SRL monitoring from July 2017 to April 2022 at the Department of Burns and Plastic Surgery, Children's Hospital of Nanjing Medical University were retrospectively collected. Clinical data were obtained from the hospital information system. Results: In total, 67 children (35 females) were enrolled. The therapeutic drug monitoring data showed that the range of measured blood trough concentrations (Ctrough) was 3.6-46.8 ng/mL. At the initial measurements, only 33% of patients were in the target concentration range (10-15 ng/mL). But this proportion became 54% at the last measurements. The whole blood-Ctrough-to-daily dose (Ctrough/Dose) ratio was significantly associated with age and body weight (BW). The patients' laboratory results did not change significantly after SRL treatment. Although the incidence of adverse events was relatively high (44.8%), most of them were mild and tolerable. 70.3% patients had total responses to SRL, whereas 29.7% children exhibited stable disease or progressive disease. No significant differences were found in Ctrough between the total response group and non-response group. Conclusions: This retrospective study revealed a high variability in SRL blood concentrations in Chinese children with VAs. Of note, pediatric patients with older age and a higher BW had a lower Ctrough/Dose ratio. It is a concern whether the range of 10-15 ng/mL is feasible for Chinese children based only on our study. Further studies recruiting more patients are required to redefine the target reference range for children with VAs.

Population pharmacokinetic study in children with vascular anomalies: body weight as a key variable in predicting the initial dose and dosing frequency of sirolimus

Background

The main challenges faced when using sirolimus in children with vascular anomalies (VAs) still include significant pharmacokinetic (PK) variability, uncertainty in the target concentration range, as well as inconsistencies in initial dosing and dosing frequency. The aim of this study is to establish a new population pharmacokinetic (PPK) model for children with VAs to guide the individualized use of sirolimus.

Methods

A PPK study was performed using data from children with VAs who received sirolimus between July 2017 and April 2022. A nonlinear mixed-effect modeling with a one-compartment model structure was applied. Monte Carlo simulation was employed to propose specific dosing recommendations to achieve the target trough concentrations (C trough) of 5-15 ng/mL.

Results

In total, 134 blood concentrations from 49 pediatric patients were used to characterize the sirolimus pharmacokinetics. Covariate analysis identified body weight (BW) as a significant factor affecting clearance (CL) in the final PPK model. The typical clearance rate and distribution volume, standardized to a BW of 16 kg, were 4.06 L/h (4% relative standard error, RSE) and 155 L (26% RSE), respectively. Optimal dosing regimens were simulated for different BWs. For a twice-daily regimen, the recommended doses were 0.05, 0.06, 0.07, and 0.08 mg/kg/day for BW of <10, 10-20, 20-40, and ≥40 kg, respectively; for a once-daily regimen, the recommended doses were 0.06, 0.07, 0.08, and 0.09 mg/kg/day for BW of <10, 10-30, 30-50, and ≥50 kg, respectively. Notably, sirolimus C trough could be maintained between 5-15 ng/mL across various dosing frequencies based on the recommended dosing regimen.

Conclusion

We established a PPK model of sirolimus for children with VAs and proposed an initial dosing strategy. Integrating initial dose and medication frequency recommendations into sirolimus' guidelines will broaden its clinical options and simplify the clinical management for childhood VAs.

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.

Defining the Role of Oral Pathway Inhibitors as Targeted Therapeutics in Arteriovenous Malformation Care

Arteriovenous malformations (AVMs) are vascular malformations that are prone to rupturing and can cause significant morbidity and mortality in relatively young patients. Conventional treatment options such as surgery and endovascular therapy often are insufficient for cure. There is a growing body of knowledge on the genetic and molecular underpinnings of AVM development and maintenance, making the future of precision medicine a real possibility for AVM management. Here, we review the pathophysiology of AVM development across various cell types, with a focus on current and potential druggable targets and their therapeutic potentials in both sporadic and familial AVM populations.

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.

Successful sirolimus treatment of spindle cell haemangiomas in a paediatric patient with Maffucci syndrome

A case of Maffucci syndrome in a paediatric patient was treated satisfactorily with sirolimus, creating an opportunity for complete surgical excision of spindle cell haemangiomas.

Coexistence of kaposiform hemangioendothelioma and capillary malformation: More than a coincidence? Two case reports

The coexistence of kaposiform hemangioendothelioma (KHE) and capillary malformation (CM) is quite rare, and few relevant studies can be found to confirm whether this phenomenon is accidental. We diagnosed and treated two such patients, revealing interesting phenomena associated with the development of vascular diseases. These cases offer the possibility that the coexistence of KHE and CM is not accidental and open up a new field of research related to pediatric vascular tumors and vascular malformations. Personalization and precision are required in the diagnosis and treatment of such patients, and the present findings provide a reliable theoretical and practical basis for further research on the pathogenesis and therapy of patients with multiple vascular diseases.

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.

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.

Preliminary results of the European multicentric phase III trial regarding sirolimus in slow-flow vascular malformations

BACKGROUNDSlow-flow vascular malformations frequently harbor activating mutations in the PI3K/AKT/mTOR cascade. Phase II trials pinpointed sirolimus effectiveness as a drug therapy. Efficacy and safety of sirolimus thus need to be evaluated in large prospective phase III trials.METHODSThe Vascular Anomaly-Sirolimus-Europe (VASE) trial, initiated in 2016, is a large multicentric prospective phase III trial (EudraCT 2015-001703-32), which evaluates efficacy and safety of sirolimus for 2 years in pediatric and adult patients with symptomatic slow-flow vascular malformations. In this interim analysis, we studied all patients enrolled up to October 2021 who received sirolimus for 12 or more months or who prematurely stopped the treatment.RESULTSThirty-one pediatric and 101 adult patients were included in this analysis; 107 completed 12 or more months of sirolimus, including 61 who were treated for the whole 2-year period. Sirolimus resulted in a clinical improvement in 85% of patients. The efficacy appeared within the first month for the majority of them. Grade 3-4 adverse events were observed in 24 (18%) patients; all resolved after treatment interruption/arrest. Sirolimus increased feasibility of surgery or sclerotherapy in 20 (15%) patients initially deemed unsuitable for intervention. Among the 61 patients who completed the 2-year treatment, 33 (54%) reported a recurrence of symptoms after a median follow-up of 13 months after sirolimus arrest. While there was no difference in efficacy, clinical improvement was faster but subsided more rapidly in PIK3CA-mutated (n = 24) compared with TIE2-mutated (n = 19) patients.CONCLUSIONSirolimus has a high efficacy and good tolerance in treatment of slow-flow vascular malformations in children and adults.TRIAL REGISTRATIONClinicalTrials.gov NCT02638389 and EudraCT 2015-001703-32.FUNDINGThe Fonds de la Recherche Scientifique (FNRS grants T.0247.19, P.C005.22, T.0146.16, and P.C013.20), the Fund Generet managed by the King Baudouin Foundation (grant 2018-J1810250-211305), the Walloon Region through the FRFS-WELBIO strategic research programme (WELBIO-CR-2019C-06), the MSCA-ITN network V.A. Cure no. 814316, the Leducq Foundation Networks of Excellence Program grant "ReVAMP" (LFCR grant 21CVD03), the European Union's Horizon 2020 research and innovation programme under grant agreement no. 874708 (Theralymph), the Swiss National Science Foundation under the Sinergia project no. CRSII5_193694, and a Pierre M. fellowship.

Toxic effects of sirolimus and everolimus on the development and behavior of zebrafish embryos

Sirolimus and everolimus have been widely used in children. These mammalian target of rapamycin (mTOR) inhibitors have shown excellent efficacy not only in organ transplant patients as immunosuppressive agents but also in patients with some other diseases. However, whether mTOR inhibitors can affect the growth and development of children is of great concern. In this study, using zebrafish models, we discovered that sirolimus and everolimus could slow the development of zebrafish, affecting indicators such as survival, hatching, deformities, body length, and movement. In addition to these basic indicators, sirolimus and everolimus had certain slowing effects on the growth and development of the nervous system, blood vessels, and the immune system. These effects were dose dependent. When the drug concentration reached or exceeded 0.5 μM, the impacts of sirolimus and everolimus were very significant. More interestingly, the impact was transient. Over time, the various manifestations of experimental embryos gradually approached those of control embryos. We also compared the effects of sirolimus and everolimus on zebrafish, and we revealed that there was no significant difference between these drugs in terms of their effects. In summary, the dose of sirolimus and everolimus in children should be strictly controlled, and the drug concentration should be monitored over time. Otherwise, drug overdosing may have a certain impact on the growth and development of children.

A randomized, placebo-controlled study to evaluate safety and pharmacokinetics of ART-001 with a novel oral pediatric formulation in healthy subjects

ART-001 is an orally available selective PI3Kα inhibitor currently being developed for the treatment of slow-flow vascular malformations (SFVMs). ART-001 used to be developed for advanced solid tumors, but was suspended largely due to significant pharmacokinetic (PK) variability in its phase I studies. This phase I, randomized, double-blinded, placebo-controlled study evaluated safety, tolerability and PK of ART-001 with a newly developed dry syrup formulation, which was designed to optimize PK properties of ART-001 and to be compliant with the pediatric population. Single and multiple doses of ART-001 were administered to healthy male adults. ART-001 was rapidly absorbed after the single and repeated doses, and the exposure of ART-001 increased with increased dose. The dry syrup formulation substantially improved the intersubject PK variability. Food decreased area under the concentration-time curve (AUC) and maximum plasma concentration by 12% and 36%, respectively. The plasma concentration had reached a steady-state on day 5 of the repeated doses of 100 mg and AUC accumulation ratio was 1.9. There were no deaths or serious adverse events. The most frequent adverse event was hyperglycemia. All cases of hyperglycemia were mild to moderate and transient, and required no medical interventions. Serum creatinine increase was observed in 300 mg once daily dosing group leading to dose discontinuation on day 5. In conclusion, it was demonstrated that the single doses and repeated doses of the ART-001 dry syrup formulation, at up to 400 and 100 mg, respectively, were safe and tolerated with favorable PK profile, supporting further clinical development for the treatment of SFVMs.

Refractory kaposiform lymphangiomatosis relieved by splenectomy

INTRODUCTION

Kaposiform lymphangiomatosis (KLA) is a rare and complex lymphatic anomaly with a poor prognosis. There is no standard treatment, and drug therapies are the most common therapeutic method. However, some patients' symptoms become gradually aggravated despite medical treatment. Splenectomy may be an alternative option when pharmacological therapies are ineffective.

MATERIALS AND METHODS

We reviewed and evaluated the cases of 3 patients with KLA who ultimately underwent splenectomy. Results: The lesions were diffusely distributed and involved the lungs and spleens of the 3 patients. Laboratory examinations revealed that all three patients had thrombocytopenia and reduced fibrinogen levels. All patients underwent symptomatic splenectomy after the medication failed. Surprisingly, their symptoms greatly improved. Histopathological investigation of the splenic lesions of the three patients confirmed the diagnosis of KLA. Immunohistochemical staining showed positivity for CD31, CD34, podoplanin, Prox-1 and angiopoietin 2 (Ang-2).

DISCUSSION

This study aimed to review the features of KLA patients treated by splenectomy and explore the underlying link between splenectomy and prognosis. The reason for the improvement after splenectomy may be related to increased Ang-2 levels and platelet activation in patients with KLA. Future research should seek to develop more targeted drugs based on molecular findings, which may give new hope for the treatment of KLA.

Long-term outcomes of sirolimus treatment for kaposiform hemangioendothelioma: Continuing successes and ongoing challenges

Treatment with sirolimus, an inhibitor of the mammalian target of rapamycin pathway, has improved the prognosis of patients with kaposiform hemangioendothelioma (KHE). However, the efficacy, durability and tolerability of long-term sirolimus treatment in patients with KHE have not been well elucidated. We performed efficacy and safety assessments based on more than 4.5 years of follow-up in patients receiving sirolimus therapy for KHE. One hundred sixty-seven patients were analyzed, including 102 (61.1%) patients with the Kasabach-Merritt phenomenon (KMP). Follow-up was conducted after a median of 56.0 months. A total of 154 (92.2%) patients had a durable response to sirolimus treatment. No difference in durable response was found between patients without KMP and patients with KMP (95.4% vs 90.2%; difference, 5.2%; 95% confidence interval [CI], -4.0% to 13.1%). Rebound growth occurred in 17.3% of patients upon sirolimus discontinuation. Early treatment discontinuation (odds ratio [OR]: 3.103; 95% CI: 1.529-6.299; P = .002) and mixed lesion type (OR: 2.271; 95% CI: 0.901-5.727; P = .047) were associated with tumor rebound growth. No KHE-related deaths occurred in this cohort. At the last follow-up, approximately 17.4% of patients had active disease and/or changes in body structures to a variable extent. Serious adverse events occurred most commonly during the first year of sirolimus therapy. Follow-up of almost 4.5 years demonstrated that the efficacy of sirolimus persisted over time and that long-term treatment with sirolimus was not associated with unacceptable cumulative toxicities. However, nonresponse, tumor relapse and long-term sequelae remained challenges despite intensified and prolonged sirolimus therapy.

Pathological angiogenesis: mechanisms and therapeutic strategies

In multicellular organisms, angiogenesis, the formation of new blood vessels from pre-existing ones, is an essential process for growth and development. Different mechanisms such as vasculogenesis, sprouting, intussusceptive, and coalescent angiogenesis, as well as vessel co-option, vasculogenic mimicry and lymphangiogenesis, underlie the formation of new vasculature. In many pathological conditions, such as cancer, atherosclerosis, arthritis, psoriasis, endometriosis, obesity and SARS-CoV-2(COVID-19), developmental angiogenic processes are recapitulated, but are often done so without the normal feedback mechanisms that regulate the ordinary spatial and temporal patterns of blood vessel formation. Thus, pathological angiogenesis presents new challenges yet new opportunities for the design of vascular-directed therapies. Here, we provide an overview of recent insights into blood vessel development and highlight novel therapeutic strategies that promote or inhibit the process of angiogenesis to stabilize, reverse, or even halt disease progression. In our review, we will also explore several additional aspects (the angiogenic switch, hypoxia, angiocrine signals, endothelial plasticity, vessel normalization, and endothelial cell anergy) that operate in parallel to canonical angiogenesis mechanisms and speculate how these processes may also be targeted with anti-angiogenic or vascular-directed therapies.

Occurrence of Rhabdomyosarcoma After Surgery Combined with oral Sirolimus for Mixed Vascular Malformation of the Tongue

Vascular malformation is the general term of a kind of lesions originated from lymphatic vessels and vascular tissues, which contains a variety of components called mixed vascular malformation. Rhabdomyosarcoma (RMS) is a kind of soft tissue sarcoma, originating from striated muscle cells or mesenchymal cells. RMS and vascular malformation mostly occur in children, and common in the head and neck, but their simultaneous occurrence is rare. A 9-year-old boy who was hospitalized for a second attack of combined vascular malformation: hemolymphangioma. The child experienced severe upper airway obstruction and tongue bleeding. Postoperative pathology demonstrated hemolymphangioma combined with RMS. Subsequently, he was transferred to the oncology department for chemotherapy and lately died of RMS with lung metastasis. The secondary RMS may be related to the usage of sirolimus. Because of its uncertain border, vascular malformation in the oral and maxillofacial region is difficult to completely remove by surgical resection, and local recurrence could be often observed. Due to its rapid progress and continuous bleeding, the possibility of malignant tumor should be considered and multidisciplinary comprehensive treatment should be actively taken. Besides, family history of related malignant tumors and immune function should be investigated in detail before choosing the application of oral sirolimus.

Oral antibiotic prophylaxis for infection in patients with vascular anomalies receiving sirolimus treatment: a multicenter retrospective study

OBJECTIVES

Patients with vascular anomalies (VAs) who receive oral sirolimus may be at high risk of infectious complications. Antibiotic prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) has been advocated. However, there have been few evidence-based analyses on this topic. This study assessed the effect of prophylactic TMP-SMZ on the incidence of infections in VA patients receiving sirolimus monotherapy.

METHODS

A retrospective, multicenter chart review was performed on all VA patients receiving sirolimus treatment from August, 2013 to January, 2021.

RESULTS

Before January 2017, 112 patients were treated with sirolimus without antibiotic prophylaxis. In the subsequent period, 195 patients were treated with TMP-SMZ for at least 12 months during sirolimus therapy. The percentage of patients with at least one serious infection during the initial 12 months of sirolimus treatment did not differ between the groups (difference, 1.1%; 95% CI - 7.0-8.0%). We observed no difference in the incidence of individual infection or total adverse events between the groups. The rate of sirolimus discontinuation due to adverse events did not differ significantly between groups.

CONCLUSIONS

We demonstrated that prophylactic TMP-SMZ does not decrease the incidence of infection or improve tolerance in VA patients receiving sirolimus monotherapy.

Novel organoid construction strategy for non-involuting congenital hemangioma for drug validation

BACKGROUND

Non-involuting congenital hemangiomas (NICHs) are fully formed vascular tumors at birth with distinctive clinical, radiologic, and histopathological profiles. In the literature, there is no effective therapy strategy for patients with NICH except surgery. Currently, no cell line or animal model exists for studying the mechanism of NICH and drug validation. We plan to construct a new strategy by constructing NICH organoids for further study.

RESULT

Here, we report a novel NICH organoid system construction and optimization process. Both HE and immunohistological staining exactly matched NICH tissue. We further performed transcriptome analysis to elucidate the characteristics of NICH organoids. Both NICH tissue and NICH organoids manifested similar trends in download sites. NICH organoids display novel features to new cells derived from organoids and show spectacular multiplication capacity. In the preliminary verification, we found that cells splitting from NICH organoids were human endothelial cells. Drug validation demonstrated that trametinib, sirolimus, and propranolol showed no inhibitory effects on NICH organoids.

CONCLUSION

Our data show that this new NICH-derived organoid faithfully captured the features of this rare vascular tumor. Our study will boost further research on the mechanism of NICH and drug filtering in the future.

Safety Evaluation of Oral Sirolimus in the Treatment of Childhood Diseases: A Systematic Review

Background: Sirolimus, a mammalian target of rapamycin inhibitor, has been widely used in pediatric patients, but the safety of sirolimus in pediatric patients has not been well determined. Objective: The objective of this study was to systematically evaluate prospective studies reporting the safety of sirolimus in the treatment of childhood diseases. Methods: The following data were extracted in a standardized manner: study design, demographic characteristics, intervention, and safety outcomes. Results: In total, 9 studies were included, encompassing 575 patients who received oral sirolimus for at least 6 months. Various adverse events occurred. The most common adverse event was oral mucositis (8.2%, 95% CI: 0.054 to 0.110). Through comparative analysis of the subgroups based on the targeted concentration range, we discovered that many adverse events were significantly higher in the high concentration group (≥10 ng/mL) than in the low concentration group (<10 ng/mL) (p < 0.01). More interestingly, we found that oral mucositis was more frequently reported in children with vascular anomalies than tuberous sclerosis complex. Conclusions: This study shows that oral sirolimus in the treatment of childhood diseases is safe and reliable. However, sirolimus treatment in the pediatric population should be strictly monitored to reduce the occurrence of serious or fatal adverse events.

Malignant Superficial Mesenchymal Tumors in Children

Malignant superficial mesenchymal tumors are a very diverse group of neoplasms with few clinical and radiological discriminatory factors. Hence, some of these cancers are rarely suspected based on clinical and radiological grounds, others may be easily misdiagnosed, and the histological analysis of a biopsy or resection is central in the diagnostic process. In children, the age at presentation is a major element of the differential diagnosis. Some tumors have a very distinct epidemiology, while others may be seen at any age. More recently, the advances in molecular biology have greatly improved the diagnosis of mesenchymal tumors and new entities are still being described. In the present review, we provide an overview of the diversity of malignant superficial mesenchymal tumors in children, including new and/or rare entities. We discuss the important diagnostic features, be they clinical, histological, or molecular. Special attention was given to the genetic features of these tumors, particularly when they were helpful for the diagnosis or treatment.

Sirolimus plus prednisolone vs sirolimus monotherapy for kaposiform hemangioendothelioma: a randomized clinical trial

The Kasabach-Merritt phenomenon (KMP) in kaposiform hemangioendothelioma (KHE) is characterized by life-threatening thrombocytopenia and consumptive coagulopathy. This study compared the efficacy and safety of sirolimus plus prednisolone vs sirolimus monotherapy as treatment strategies for KHE with KMP in the largest cohort to date. Participants were randomized to receive either sirolimus in combination with a short course of prednisolone or sirolimus monotherapy for at least 12 months. The primary outcome was defined as achievement of a durable platelet response (platelet count >100 × 109/L) at week 4. Participants completed efficacy assessments 2 years after the initial treatment. At week 4, a durable platelet response was achieved by 35 of 37 patients given sirolimus and prednisolone compared with 24 of 36 patients given sirolimus monotherapy (difference 27.9%; 95% confidence interval, 10.0-44.7). Compared with the sirolimus monotherapy group, the combination treatment group showed improvements in terms of measures of durable platelet responses at all points during the initial 3-week treatment period, median platelet counts during weeks 1 to 4, increased numbers of patients achieving fibrinogen stabilization at week 4, and objective lesion responses at month 12. Patients receiving combination therapy had fewer blood transfusions and a lower total incidence of disease sequelae than patients receiving sirolimus alone. The frequencies of total adverse events and grade 3-4 adverse events during treatment were similar in both groups. The responses seen in patients with KHE with KMP were profound and encouraging, suggesting that sirolimus plus prednisolone should be considered a valid treatment of KHE with KMP. This trial was registered at www.clinicaltrials.gov as #NCT03188068.

Efficacy and safety of oral sirolimus for high-flow vascular malformations in real clinical practice

BACKGROUND

Vascular malformations are a complex pathology with few treatment options. In previously published studies, oral sirolimus (rapamycin) has shown promising results in the treatment of low-flow vascular malformations, but its usefulness in high-flow vascular malformations is controversial.

AIM

To evaluate the efficacy and safety of sirolimus for the treatment of high-flow vascular malformations in real-life practice.

METHODS

In a unit specializing in vascular anomalies, patients treated with oral sirolimus for high-flow vascular malformations were located by consulting the drug dispensations. Reviewing the electronic medical records, data on patient demographics, vascular malformation characteristics, treatments, toxicity and clinical course were collected and statistically analysed.

RESULTS

Nine patients with vascular malformations were included: eight had arteriovenous malformation and one had arteriovenous fistula. Six of these malformations were isolated while three were part of a syndrome. Sirolimus was initiated at a dosage of 1-4 mg/day to be taken as a single dose. Partial response was observed in eight of the nine patients (88.9%) with high-flow vascular malformation, while worsening was observed in the remaining patient. The treatment was well tolerated and at the most recent follow-up, five patients remained on treatment with oral sirolimus.

CONCLUSION

Our results show that oral sirolimus is a well-tolerated therapeutic option, with an excellent safety profile, which can be useful in the long-term stabilization of patients with high-flow vascular malformations. Single-daily dosage may improve long-term adherence to treatment without worsening its effectiveness.