Sirolimus for the treatment of children with various complicated vascular anomalies

Sirolimus experience in adult patients with vascular malformations

AimSirolimus, 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.MethodsWe 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.Results38 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.ConclusionIn this study, we found sirolimus was efficacious and well tolerated in adult patients with vascular malformation.

In-human clinical experience with direct stick embolization of low-flow vascular malformations using a mammalian target of rapamycin inhibitor

BACKGROUND

Although direct stick embolization (DSE) of low-flow vascular malformations (LFVMs) with off-label embolotherapeutic compounds is the current mainstay of therapy, systemic oral mammalian target of rapamycin (mTOR) inhibition has evolved into an important adjunctive therapy that is associated with frequent blood draws, systemic toxicity, and rebound signs and symptoms upon cessation. We herein report our experience with in-human DSE of LFVMs with an mTOR inhibitor for direct, intralesional targeting of the culprit mutated pathway without repeated systemic exposure.

METHODS

Since 2020, 33 procedures involving DSE were performed in 25 patients with LFVMs using a patented formulation and technique involving the intravenously compatible mTOR inhibitor Yale-OCR7737, used as a liquid compound in a collagen matrix emulsion for added viscosity and intralesional residence. Data were maintained prospectively and reviewed retrospectively for technical success (successful catheterization of the lesion and intralesional delivery of compound), clinical success (improvement in signs/symptoms with radiologically documented reduction in flow and/or volume of treated lesion), complications, side effects, and reinterventions.

RESULTS

From 2020 to 2023, 33 procedures involving DSE were performed using Yale-OCR7737 in 25 patients (10 men [40%]; 15 women [60%]; mean age, 28 years [range, 1-70 years]) with LFMVs involving the head/neck (48%) and limbs (40%); 88% were nonsyndromic and 12% had Klippel-Trenaunay syndrome; 68% exhibited venous malformations, and 32% had lymphatic malformations. Technical and clinical success rates were 100%. Mean DSE sessions per patient was 1.4 (range, 1-5). Localized intravascular coagulopathy was present after 16 DSE procedures (49%); D-dimer improved after DSE in 7 cases. No perioperative or delayed complications occurred. Side effects were seven cases (21%) of self-limited, transient, oral aphthous ulcers.

CONCLUSIONS

Our findings suggest that DSE of LFVMs with mTOR inhibitors (Yale-OCR7737) may be safe and effective. This may represent the new embolotherapeutic frontier in the endovascular treatment of LFMVs.

Treatments and Outcomes of Pediatric Head and Neck Lymphatic Malformations: A 20-Year Single Institution Experience

OBJECTIVE

Examine the management and outcomes of pediatric head and neck lymphatic malformations (HNLMs).

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary academic hospital.

METHODS

Patients aged 18 years or younger treated for HNLMs at Johns Hopkins Hospital from 2000 to 2023 were identified. Demographics, clinical characteristics, and treatment courses were recorded from charts. Outcome measures included estimated clinical post-treatment size reduction and complications. Fisher's exact test was performed for comparisons between treatments.

RESULTS

We identified 101 pediatric patients (50.5% female) with HNLMs. Fifty-two received unimodal treatment, 11 received multimodal treatment, and 38 underwent active observation or no treatment. Of those who received treatment, 44% had their first treatment before 2 years of age. 54.5% of all patients received sclerotherapy. Sclerotherapy caused nearly complete or complete resolution in 52.2% (n = 24) of low-stage (de Serres Stages 1-3) HNLMs and complete resolution in 26.1%. Most (71.4%) high-stage (de Serres Stages 4-5) malformations demonstrated limited size reduction response to all treatments. Surgery had a higher all-inclusive complication rate (25%) compared to sclerotherapy (17%). Multimodal treatment strategies were most often used to treat microcystic malformations of all stages, achieving a 42.9% nearly complete or complete resolution rate.

CONCLUSION

Low-stage and macrocystic pediatric HNLMs respond well to treatment. Sclerotherapy had the lowest complication rate. High-stage malformations had limited size reduction response to multimodal treatment. As new medical therapies continue to develop, opportunities for improved treatment algorithms will emerge.

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.

Klippel-Trenaunay Syndrome: A Case Study of Severe Anemia in a Rare Vascular Disorder

Klippel-Trenaunay syndrome (KTS) is a rare congenital vascular disorder involving varicosities, cutaneous vascular malformations, and hypertrophy of soft tissues and bones. It is often linked to PIK3CA gene mutations. It affects the lymphatic, capillary, and venous systems. The diagnosis is usually based on clinical presentation, supplemented by magnetic resonance imaging (MRI) and computed tomography (CT) imaging. This case involves a 43-year-old male diagnosed with KTS after presenting with severe anemia (hemoglobin 2.5 g/dL) and left lower limb swelling with varicosities. Investigations revealed hepatosplenomegaly, hemangiomas, rectosigmoid malformations, an enlarged inferior vena cava (IVC), and vascular congestion. MRI confirmed an extensive veno-lymphatic malformation in the left lower limb. The case highlights KTS's complex presentation, emphasizing the importance of timely diagnosis, multidisciplinary care, and ongoing monitoring to manage its complications. Further research is needed to enhance treatment strategies for this rare condition.

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.

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.

SOLAMEN syndrome with cardiovascular damage

SOLAMEN syndrome is a rare, recently recognized congenital syndrome that is characterized by progressive and hypertrophic diseases involving multiple systems, including segmental overgrowth, lipomatosis, arteriovenous malformation (AVM) and epidermal nevus. According to literatures, SOLAMEN syndrome is caused by heterozygous PTEN mutation. Phenotypic overlap complicates the clinical identification of diseases associated with PTEN heterozygous mutations, making the diagnosis of SOLAMEN more challenging. In addition, SOLAMEN often presents with segmental tissue overgrowth and vascular malformations, increasing the possibility of misdiagnosis as klipple-trenaunay syndrome or Parks-Weber syndrome. Here, we present a case of a child presenting with macrocephaly, patchy lymphatic malformation on the right chest, marked subcutaneous varicosities and capillaries involving the whole body, overgrowth of the left lower limb, a liner epidermal nevus on the middle of the right lower limb, and a large AVM on the right cranial thoracic entrance. Based on the typical phenotypes, the child was diagnosed as SOLAMEN syndrome. detailed clinical, imaging and genetic diagnoses of SOLAMEN syndrome was rendered. Next-generation sequencing (NGS) data revealed that except for a germline PTEN mutation, a PDGFRB variant was also identified. A subsequent echocardiographic examination detected potential cardiac defects. We suggested that given the progressive nature of AVM and the potential severity of cardiac damage, regular echocardiographic evaluation, imaging follow-up and appropriate interventional therapy for AVM are recommended.

[A Uncommon Case: Kasabach-Merritt syndrome with VACTERL Association]

The Kasabach-Merrit syndrome is characterized as the association of a vascular tumor, typically a caposiform hemangioendothelioma and rarely a tufted hemangioma, and a severe consumptive coagulopathy with potentially life-threatening thrombocytopenia. The severe coagulopathy with increased bleeding tendency must be considered before invasive procedures and often requires repeated platelet concentrate substitutions. We present a case of a mature male neonate with Kasabach-Merritt- Syndrome as well as VACTERL association. The VACTERL association describes a group of malformations. Our patient presented with anal atresia combined with tethered cord, and left renal agenesis. The VACTERL association as well as Kasabach-Merritt syndrome were found to be independent pathologies within this patient. A common occurrence or an association with each other has not been described in the literature so far. The challenging coagulation setting due to severe thrombocytopenia complicated the surgical management so far. Finally, mTOR-inhibitor sirolimus was successful in terms of tumor reduction and especially reduction of platelet consumption.

Shear stress and pathophysiological PI3K involvement in vascular malformations

Molecular characterization of vascular anomalies has revealed that affected endothelial cells (ECs) harbor gain-of-function (GOF) mutations in the gene encoding the catalytic α subunit of PI3Kα (PIK3CA). These PIK3CA mutations are known to cause solid cancers when occurring in other tissues. PIK3CA-related vascular anomalies, or "PIKopathies," range from simple, i.e., restricted to a particular form of malformation, to complex, i.e., presenting with a range of hyperplasia phenotypes, including the PIK3CA-related overgrowth spectrum. Interestingly, development of PIKopathies is affected by fluid shear stress (FSS), a physiological stimulus caused by blood or lymph flow. These findings implicate PI3K in mediating physiological EC responses to FSS conditions characteristic of lymphatic and capillary vessel beds. Consistent with this hypothesis, increased PI3K signaling also contributes to cerebral cavernous malformations, a vascular disorder that affects low-perfused brain venous capillaries. Because the GOF activity of PI3K and its signaling partners are excellent drug targets, understanding PIK3CA's role in the development of vascular anomalies may inform therapeutic strategies to normalize EC responses in the diseased state. This Review focuses on PIK3CA's role in mediating EC responses to FSS and discusses current understanding of PIK3CA dysregulation in a range of vascular anomalies that particularly affect low-perfused regions of the vasculature. We also discuss recent surprising findings linking increased PI3K signaling to fast-flow arteriovenous malformations in hereditary hemorrhagic telangiectasias.

Impact of puberty on procedure frequency for treatment of simple head and neck lymphatic and venous malformations

OBJECTIVE

Puberty has been shown to accelerate growth of vascular malformations, including lymphatic (LM) and venous malformations (VM). This study aims to compare the number of procedures performed before and after puberty in patients with LM and VM to assess whether the onset of puberty results in higher treatment frequency.

METHODS

A retrospective review of head and neck LM and VM patients who were evaluated between January 2009 and December 2019 was performed. Patient demographics, lesion characteristics, and procedural details were recorded. For the purposes of this study, 11 years or older in females and 12 years or older in males were the established cut-offs for the onset of puberty.

RESULTS

After initial screening of 357 patients, 83 patients were included in the study based on inclusion criteria. There were 34 patients with LM (41 %) and 49 with VM (59 %). The mean age at diagnosis was 6.1 ± 10.9 years (LM: 4.2 ± 7.0, VM: 7.4 ± 12.9, p = 0.489). 68 patients underwent treatments, which included sclerotherapy, surgical excision, and/or laser. For all patients, the average number of lifetime treatments when initiated before puberty was 3.78 ± 2.81 and when initiated after puberty was 2.17 ± 1.37 (p = 0.022). Patients diagnosed pre-puberty were more likely to undergo treatments vs. those diagnosed after puberty (OR 10.00, 95 % CI: 2.61-38.28, p < 0.001).

CONCLUSION

We found that the number of treatments was fewer in those who started treatment after puberty. This finding suggests that providers may elect to proceed with observation in asymptomatic patients, given that waiting until after the onset of puberty has not shown an increase in the procedural load on patients.

Contemporary management of extracranial vascular malformations

Vascular malformations are congenital vascular anomalies that originate because of disorganized angiogenesis, most commonly from spontaneous somatic genetic mutations. The modern management of vascular malformations requires a multidisciplinary team that offers patients the gamut of medical, surgical, and percutaneous treatment options with supportive care. This manuscript discusses the standard and contemporary management strategies surrounding extracranial vascular malformations and overgrowth syndromes.

Updates on Diagnosis and Treatment of PIK3CA-Related Overgrowth Spectrum

ABSTRACT

Hyperactivation of the PI3K/AKT/mTOR signaling pathway caused by PIK3CA mutations is associated with a category of overgrowth syndromes that are defined as PIK3CA -related overgrowth spectrum (PROS). The clinical features of PROS are highly heterogeneous and usually present as vascular malformations, bone and soft tissue overgrowth, and neurological and visceral abnormalities. Detection of PIK3CA variants is necessary for diagnosis and provides the basis for targeted therapy for PROS. Drugs that inhibit the PI3K pathway offer alternatives to conventional therapies. This article reviews the current knowledge of PROS and summarizes the latest progress in precise treatment, providing new insights into future therapies and research goals.

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.

Response to sirolimus in capillary lymphatic venous malformations and associated syndromes: Impact on symptomatology, quality of life, and radiographic response

BACKGROUND

Capillary lymphatic venous malformations (CLVM) and associated syndromes, including Klippel-Trenaunay syndrome (KTS) and congenital lipomatous overgrowth, vascular malformation, epidermal nevi, skeletal, and spinal syndrome (CLOVES), are underrecognized disorders associated with high morbidity from chronic pain, recurrent infections, bleeding, and clotting complications. The rarity of these disorders and heterogeneity of clinical presentations make large-scale randomized clinical drug trials challenging. Identification of PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha [gene]) mutations in CLVM has made targeted medications, such as sirolimus, attractive treatment options. The aim of this study was to investigate the safety and efficacy of sirolimus therapy in CLVM.

PROCEDURE

A combined prospective and retrospective cohort of pediatric and young adult patients with CLVM treated with sirolimus was evaluated for disease response, including symptom improvement, quality of life (QOL), and radiologic response. Sirolimus dosing regimens and toxicities were also assessed.

RESULTS

Twenty-nine patients with CLVM, including KTS and CLOVES, were included. Ninety-three percent of patients reported improved QOL, and 86% had improvement in at least one symptom. Most significantly, improvement was noted in 100% of patients with bleeding and 89% with thrombotic complications with corresponding decreases in mean D-dimer (p = .008) and increases in mean fibrinogen (p = .016). No patients had progressive disease on sirolimus. Most common side effects included neutropenia, lymphopenia, infection, and aphthous ulcers/stomatitis. No toxicities were life-threatening, and none required long-term discontinuation of sirolimus.

CONCLUSION

Sirolimus appears to be effective at reducing complications and improving QOL in patients with CLVM and associated syndromes. In this patient cohort, sirolimus was well tolerated and resulted in few treatment-related toxicities.

Vascular malformations: An overview of their molecular pathways, detection of mutational profiles and subsequent targets for drug therapy

Vascular malformations are anomalies in vascular development that portend a significant risk of hemorrhage, morbidity and mortality. Conventional treatments with surgery, radiosurgery and/or endovascular approaches are often insufficient for cure, thereby presenting an ongoing challenge for physicians and their patients. In the last two decades, we have learned that each type of vascular malformation harbors inherited germline and somatic mutations in two well-known cellular pathways that are also implicated in cancer biology: the PI3K/AKT/mTOR and RAS/RAF/MEK pathways. This knowledge has led to recent efforts in: (1) identifying reliable mechanisms to detect a patient's mutational burden in a minimally-invasive manner, and then (2) understand how cancer drugs that target these mutations can be repurposed for vascular malformation care. The idea of precision medicine for vascular pathologies is growing in potential and will be critical in expanding the clinician's therapeutic armamentarium.

Magnitude and relevance of change in health-related quality of life in patients with vascular malformations treated with sirolimus

Introduction

Vascular malformations are rare congenital anomalies of the vascular system, which can involve the capillaries, veins, arteries, lymphatics, or a combination of vessel types. Patients with vascular malformations experience an impaired health-related quality of life (HRQoL) because of their symptoms (e.g., pain, swelling, and bleeding) and psychosocial distress. Sirolimus is an effective drug used in the medical treatment of these patients; however, relatively little is known about the effect of sirolimus on specific changes in the HRQoL domains and its magnitude.

Methods

The magnitude of change (effect size) following intervention is more informative to clinical practitioners than statistically significant but clinically unimportant changes; therefore, this study aimed to examine the magnitude and meaningfulness of change in the HRQoL of children and adults with vascular malformations following sirolimus treatment using low target levels.

Results

In total, 50 patients with vascular malformations (19 children, 31 adults) were included in this study. These patients experienced a lower HRQoL than the general population, with the adults reporting a significantly lower score in almost all domains. A 6-month sirolimus treatment improved the HRQoL in 29 patients, including 77.8% of the children (Pediatric Quality of Life Inventory score [PedsQL]) and 57.7% of the adults (Short Form 36 [SF-36]). The effect sizes of sirolimus for each SF-36/PedsQL domain ranged from 0.19 to 1.02. The clinically relevant moderate magnitude of changes was seen in the domains of the children's reports: "Physical functioning" and "Social functioning" and in the domains of the parent reports: "Social functioning," "School functioning," and "Psychosocial." A high-magnitude change was seen in the domains "Emotional functioning" and "Psychosocial" in the children's reports and "Physical functioning" in the parent reports. In addition, the moderate magnitude of changes was also seen in the adults SF-36: in all domains except for "Role limitations-physical problems," "Role limitations-emotional problems," and "General health perception."

Conclusion

We believe this is the first study showing the magnitude of change in HRQoL after sirolimus treatment in patients with vascular malformations. Before treatment, these patients experienced an impaired HRQoL compared with the general Dutch population. A 6-month sirolimus treatment with low target levels led to moderate-to-high clinically relevant changes in multiple domains, which significantly improved the HRQoL.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03987152?cond=Vascular+Malformations&cntry=NL&city=Nijmegen&draw=2&rank=1, identifier: NCT03987152.

Long-term outcomes of lymphatic malformations in children: An 11-year experience from a tertiary referral center

BACKGROUND

Lymphatic malformations (LMs) are benign, congenital lesions that display considerable heterogeneity in terms of size, location and characteristics. This study aims to describe the long-term outcomes of current management strategies for patients with simple (cystic) LMs.

METHODS

The case records of all patients (age ≤16 years) with simple (cystic) LMs at our tertiary institution between 2008 and 2019 were assessed for clinical features, imaging and details of management, including complications.

RESULTS

Of a total of 164 patients (60% male), 66% were diagnosed aged <2 years. The median follow-up was 5 (0.3-16) years from diagnosis. LMs were located in the head and neck (40%), extremities (27%), trunk (23%), mediastinum (4%), or intra-abdominally (6%). Types were macrocystic in 47%, microcystic in 21% and mixed in 32%. Sclerotherapy was the most common intervention (38%). Primary surgery had been performed in 12%. Symptomatic improvement, reduction in size, or complete regression were observed in 82/102 (80%) of LMs after interventions; complications from treatment were uncommon (Clavien-Dindo grade I-II: 6%; grade III-IIId: 1%). Sixty-two patients (38%; median age 0.5 (range, 0-12) years) had not required interventions to date; spontaneous regression of the LM occurred in 16 (26%) of these expectantly followed-up cases.

CONCLUSIONS

Most studies to date have focused on LMs in selected anatomical locations. Herein the outcomes of an entire population from a single tertiary unit of patients are presented, demonstrating the wide heterogeneity of simple (cystic) LMs and highlighting the importance of individualized, multidisciplinary approaches to care in achieving optimal outcomes.

No association of sirolimus with wound complications in children with vascular anomalies

INTRODUCTION

Sirolimus has demonstrated effectiveness as a treatment option for several types of vascular anomalies; however, it has a potential side effect of delayed surgical wound healing. The purpose of this study was to evaluate the association of sirolimus with postoperative complications in the pediatric vascular anomaly population.

METHODS

A retrospective cohort study was performed for children with a vascular anomaly who underwent excision or debulking of the anomaly from 2015 to 2020. Patient demographics, vascular anomaly characteristics, operative variables, sirolimus dosing information, and perioperative outcomes were collected. Univariate analysis was performed to compare outcomes based on the administration of sirolimus.

RESULTS

Forty-seven patients with vascular anomalies underwent 57 surgical procedures (36 without perioperative sirolimus, 21 with perioperative sirolimus). The median age at the time of surgery was seven years (IQR 1.7-14.0). The most common anomalies were lymphatic and venolymphatic malformations. Of the patients administered perioperative sirolimus, the median preoperative and postoperative sirolimus levels were comparable (preoperative 6.9 ng/mL (IQR 4.9-10.1), postoperative 6.5 ng/mL (IQR 4.7-9.4)). The rate of postoperative complications (sirolimus 19%, without sirolimus 11%; p = 0.45) and wound complications (sirolimus 14%, without sirolimus 6%; p = 0.26) were comparable between the cohorts.

CONCLUSION

Our results suggest sirolimus may not significantly increase perioperative complication rates in pediatric patients undergoing resection of their vascular anomaly.

LEVEL OF EVIDENCE

Level III.

Defining vascular anomaly phenotypes in children based on a systematic literature search: A critical step in developing a single severity score for interventional clinical trials

INTRODUCTION

Genetically targeted drugs in vascular anomalies (VA) are used despite the absence of a validated severity score. The aim of this study was to evaluate the feasibility of grouping phenotypic VA clinical characteristics into a single severity score.

METHODS

A systematic literature review including children treated with sirolimus accompanied by a detailed description of phenotype and management was conducted. Demographic data and clinical features were extracted to define distinct categories of phenotypes.

RESULTS

Children with VA display two main phenotypes regardless of VA subtype, which may overlap. A systemic phenotype results from direct invasion and compression of vital structures generally leading to hospitalization and aggressive management in infancy. A functional phenotype is associated with chronic pain and disability manifesting mainly during early adolescence and managed in the outpatient setting.

CONCLUSION

The two distinct phenotypes described could be the basis for developing a unified scoring system for VA severity assessment.

Institutional Management of Abdominal Lymphatic Malformations: Evolution of Treatment Over a Decade

INTRODUCTION

Abdominal lymphatic malformations (LM) have been historically managed with surgical resection; however, sclerotherapy and sirolimus have emerged as effective therapies. The purpose of our study is to evaluate our institutional change in management and outcomes for abdominal LM over the past decade.

METHODS

A retrospective cohort study was performed for all children with an abdominal LM managed at our multidisciplinary Vascular Anomalies Center from 2011 to 2020. Patient demographics, symptoms, treatment, treatment response, and complications were analyzed with descriptive statistics.

RESULTS

Twenty-nine patients with abdominal LM were identified with a median age at treatment of 6 y (interquartile range 3-14). A majority of lesions were identified as macrocystic (n = 18, 62%). The most common intervention was surgery alone (n = 14, 48%) followed by sirolimus alone (n = 4, 14%), and sclerotherapy + sirolimus (n = 4, 14%). Five patients were observed due to lack of symptoms at presentation. Prior to 2017, 91% (10/11) of LM were treated with surgery alone. Following 2017, only 31% (4/13) were treated with surgery alone. Sixty-seven percent (16/24) of treated patients had >95% reduction in LM maximum diameter. A majority of patients (23/24) who received treatment had improvement or resolution of symptoms at median 9-mo follow-up. Only three patients had post-treatment complications, including a drain site infection, small bowel obstruction, and an aspiration event. Complications only occurred after sclerotherapy sessions.

CONCLUSIONS

Over the study period, our institution has transitioned to initial management of symptomatic abdominal LM with sclerotherapy and/or sirolimus with almost all treated patients having excellent or satisfactory treatment response. Post-treatment complications were rare.

Case report: A rare case of retroperitoneal kaposiform hemangioendothelioma with spinal involvement without abnormal platelet count in 18F-FDG PET/CT

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm that mostly appears in infancy or early childhood. Most KHE occurred on the limbs and trunk with cutaneous lesions. Approximately 12% of KHE patients manifested as deep masses and spinal involvement is extremely rare. KHE may develop into life-threatening thrombocytopenia and consumptive coagulopathy, known as the Kasabach-Merritt phenomenon (KMP), especially in patients with retroperitoneal involvement. The thrombocytopenia is usually severe, with a median platelet count of 21 × 10⁹/L at the initial presentation of KMP. Here, firstly we described a case of a 13-month-old girl with KHE who presented the movement limitation of the lower extremity caused by spinal involvement with a normal platelet count. ¹⁸F-fluorodeoxyglucose-positron emission tomography/CT (¹⁸F-FDG PET/CT) showed mildly elevated metabolism in the lesion, suggesting a probably low-grade malignant tumor. Then the patient was diagnosed with KHE by biopsy. After 6-month sirolimus monotherapy, the size of the retroperitoneal lesion was reduced significantly and the patient showed improvement in clinical symptoms. This case demonstrated the advantage of ¹⁸F-FDG PET/CT in the evaluation of disease activity in KHE and the possibility of using ¹⁸F-FDG PET/CT to guide therapy and prognostication.

Effective low-dose sirolimus regimen for kaposiform haemangioendothelioma with Kasabach-Merritt phenomenon in young infants

AIMS

Management of kaposiform haemangioendotheliomas (KHE) with Kasabach-Merritt phenomenon is challenging in young infants who are subjected to developmental pharmacokinetic changes. Sirolimus, sometimes combined with corticosteroids, can be used as an effective treatment of KHE. Simultaneously, toxicities such as interstitial pneumonitis related to the use of sirolimus may be fatal. As infants have a very low CYP3-enzyme expression at birth, which rises during ageing, we hypothesize that a reduced metabolization of sirolimus might lead to high sirolimus serum levels and low dose may be sufficient without the side effects.

METHODS

A case series of 5 infants with kaposiform haemangioendothelioma with Kasabach-Merritt phenomenon was analysed retrospectively. All infants were treated with sirolimus 0.2 mg/m2 every 24 or 48 hours according to their age. Prednisone was added to the therapy for additional effect in 4 patients.

RESULTS

In all patients, low dose of sirolimus led to therapeutic sirolimus levels (4-6 ng/mL). All infants (aged 4 days-7 months) had a complete haematological response, without serious adverse events. In all patients, the Kasabach-Merritt phenomenon resolved, the coagulation profile normalized and tumour size reduction was seen.

CONCLUSION

Low-dose sirolimus treatment is safe for infants with kaposiform haemangioendothelioma and Kasabach-Merritt phenomenon. It is essential to realize that during the first months of life, metabolism is still developing and enzymes necessary to metabolise drugs like sirolimus still have to mature. To avoid toxic levels, the sirolimus dosage should be based on age and the associated pharmacological developments.

Sirolimus as a promising drug therapy for blue rubber bleb nevus syndrome: Two-case report

Blue rubber bleb nevus syndrome is a very rare systemic vascular malformation frequently affecting the skin and the gastrointestinal tract. The pathogenesis of the disease is still unclear, and the standard treatment does not exist. This study reports two blue rubber bleb nevus syndrome cases, of which the second patient received the TEK gene mutations detection and got a low-dose sirolimus therapy, compared with the first patient who was not treated with sirolimus. The report shows some positive findings of TEK gene mutations and the efficacy of sirolimus treatment. We postulate that the TEK gene mutations play an important role in the pathogenesis. The mutations of different locations of the TEK gene cause a wide range of activating TIE2 mutations, which could stimulate the mammalian target of rapamycin signaling pathways to mediate angiogenesis, resulting in different clinical phenotypes of cutaneomucosal venous malformations. Sirolimus could effectively block the upstream and downstream factors of mammalian target of rapamycin signaling pathways to achieve the antiangiogenic effect. The initial dose of sirolimus can be 0.05–0.1 mg/kg/d for a trough level of 5–15 μg/L in the treatment of blue rubber bleb nevus syndrome. However, a lower-dose sirolimus is also effective while minimizing the side effects.

Efficacy of sirolimus in children with lymphatic malformations of the head and neck

Purpose

Children with extensive lymphatic malformations of the head and neck often suffer from functional impairment and aesthetic deformity which significantly affect the quality of life and may be life-threatening. Treatment with sirolimus has the potential to improve symptoms and downsize lymphatic malformations. This systematic review summarizes the current information about sirolimus treatment of lymphatic malformations of the head and neck in children, its efficacy and side effects.

Methods

A systematic search of the literature regarding studies on sirolimus treatment of children with lymphatic malformations of the head and neck was performed in PubMed, Embase, and Google Scholar up to July 2021 with the search terms “lymphatic malformation”, “lymphangioma”, “cystic hygroma”, “low-flow malformation”, “sirolimus”, “rapamycin”, “mTOR inhibitor” and “children”.

Results

In all, 28 studies including 105 children from newborn to 17 years treated with sirolimus for lymphatic malformations of the head and neck were analyzed. The most frequent initial dose was 0.8 mg/m² per dose, twice daily at 12-h interval. The target blood level differed between studies, 10–15 ng/mL and 5–15 ng/mL were most often used. More than 91% of the children responded to sirolimus treatment which lasts from 6 months to 4 years. Typical side effects were hyperlipidemia, neutropenia and infections.

Methods

Sirolimus could be an effective treatment for children with large complicated lymphatic malformations of the head and neck. As not all patients will benefit from treatment, the decision to treat sirolimus should be made by a multidisciplinary team.

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.

Kaposiform hemangioendothelioma of the bone in children and adolescents

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that mainly occurs during infancy or early childhood. Approximately 70% of cases are complicated by Kasabach-Merritt phenomenon. Although osseous extension of the primary lesion is relatively common, primary bone involvement by KHE is rare. Given the paucity of literature on primary KHE of the bone, we report a case series of primary KHE of the bone treated at our institution and describe the clinical presentation, radiologic and pathologic findings, management and outcomes.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

A prospective multicenter study of sirolimus for complicated vascular anomalies

OBJECTIVE

Complicated vascular anomalies (VAs) can be intractable and uncontrollable using conventional treatment and can result in lethal outcomes. We undertook a prospective, multicenter phase II trial to evaluate the efficacy and safety of sirolimus in pediatric patients with complicated VAs.

METHODS

Eligible patients were required to be aged 0 to 14 years and to have a complicated VA. The patients were treated with daily oral sirolimus for 12 months. The primary endpoint was the response, which was measured using sequential volumetric magnetic resonance imaging. The secondary endpoints were the disease severity score and quality of life.

RESULTS

Of 126 patients enrolled on an intention-to-treat basis, 98 (77.8%) had had an objective response to sirolimus, with a ≥20% decrease in lesion volume. Compared with those with arteriovenous malformations, the response rates were higher (>80%) for patients with common lymphatic malformations, venous malformations, kaposiform hemangioendothelioma, and combined malformations with a prominent venous and/or lymphatic component (P < .05). Improvements in the disease severity score and quality of life were obtained in 83.3% and 79.4% of patients, respectively. The most common adverse event was mucositis in 47 patients. More serious adverse events included reversible grade 4 pneumonitis in 3 patients and grade 4 upper respiratory infection in 1 patient. All these adverse events were considered at least possibly related to the treatment.

CONCLUSIONS

Sirolimus is an apparently effective option for pediatric patients with various types of complicated VAs. Close monitoring of possible adverse events is required. The results from the present trial are the basis for future prospective studies using new therapeutic approaches.

Acquired cryptorchidism: an unexpected consequence of inguinoscrotal lymphatic malformation treated with Eppikajutsuto

Lymphatic malformation (LM) that causes inguinoscrotal swelling is extremely rare. Surgery, sclerotherapy and pharmacotherapy have been reported as possible treatment options for LM. Recently, Eppikajutsuto (TJ-28), a traditional Japanese herbal medicine has emerged as therapeutic option for LM. We report the case of a 2-year-old boy who presented with a left inguinoscrotal swelling, which was diagnosed as retroperitoneal LM extending into the left scrotum. The surgical approach was less favourable, given the risk of damaging the testicular vasculature or the spermatic cord. Therefore, the patient received medical treatment with TJ-28. As a result, a volume reduction of 83% was obtained, as well as the unexpected consequence of the left testicle retracting into the inguinal area. Laparoscopic exploration was performed and a small bulge on the internal inguinal ring was detected. The patient's acquired cryptorchidism was subsequently treated by orchidopexy.

Intermittent Administration Regimen of Sirolimus for Refractory Cervicofacial Lymphatic Malformation

BACKGROUND

The cervicofacial lymphatic malformations (LMs) often have poor outcomes due to their microcystic component and diffuse infiltration. Mostly, traditional treatments are inadequate for these refractory cases. Recent researches have shown that sirolimus is effective in the treatment of complicated LMs, however, there is still no standard strategy.

OBJECTIVE

To evaluate the efficacy and safety of intermittent oral sirolimus in treating refractory cervicofacial LMs as a second-line treatment.

METHODS

Fifteen pediatric patients of refractory cervicofacial LMs were retrospectively analyzed in this study. All the cases had received traditional therapy before, but could not completely control the symptoms and eliminate lesions. As a remedy, sirolimus was then proceeded with an intermittent administration regimen, that is 3 continuous months as a course and started the next course after 1 month interval. The clinical characteristics, imaging data of patients, the changes in the signs and symptoms observed, and associated adverse effects were collected and analyzed.

RESULTS

The patients initiated sirolimus therapy at the average age of 2.3 years (range 28 days-8 years 9 months). At the end point of the study, 2 patients remained on sirolimus in continuous courses of treatment. Of 13 patients who withdrawn therapy, 4 had restarted due to recurrence of symptoms and re-expansion of LMs. All patients demonstrated reduction in residual LMs and complete disappearance of symptoms during treatment, and 2 patients with complete resolution on imaging. Toxicity was tolerant in this series. There was no patient develop opportunistic or systemic bacterial infection.

CONCLUSIONS

Sirolimus is commended as a second-line treatment to treat intractable cervicofacial LMs after failure of traditional therapy. The intermittent administration regimen is efficacious to completely control symptoms and partially reduce residual lesions with good tolerance and limited side effects.

Newcomers in Vascular Anomalies

Vascular anomalies are composed of tumors and malformations and with overlapping histologies, thus are often misdiagnosed or labeled with imprecise terminology. Lesions are common and usually diagnosed during infancy or childhood; the estimated prevalence is 4.5%. Vascular tumors rapidly enlarge postnatally and demonstrate endothelial proliferation. Malformations are errors in vascular development with stable endothelial turnover; they are typically named based on the primary vessel that is malformed (capillary, arterial, venous, lymphatic). This article reviews the pathologic and molecular genetic characteristics for select recently described vascular anomalies.

Histopathological evaluation of the effectiveness of oral Eppikajutsuto treatment for lymphatic malformation

BACKGROUND

Lymphatic malformation (LM) is a congenital disease caused by lymphatic vessel malformation. Although standard therapies for LMs are sclerotherapy and/or surgical excision, a new therapy using Japanese herbal medicine Eppikajutsuto (TJ-28) has been recently reported as clinically effective. We aimed to experimentally confirm the therapeutic effectiveness of TJ-28 for LMs.

METHODS

LM lesions were generated in the mesentery and peritoneum of mice by intraperitoneal injection of Freund's incomplete adjuvant. Mice with LMs were treated by gavage or dietary administration of TJ-28 for 2 months. Formalin-fixed paraffin-embedded tissue sections of mesentery and peritoneum tissues were histologically and immunohistochemically examined by focusing on lymph nodes and perinodal lymph vessels.

RESULTS

Multiple Freund's incomplete adjuvant-associated foreign-body granulomas were formed in the mesentery and peritoneum, resulting in congestion of lymph fluid and dilatation of lymph vessels. The numbers and sizes of lymph nodes were not significantly different between TJ-28-treated and control groups. However, the luminal areas of lymphatic vessels were reduced significantly in the TJ-28 treatment group by both gavage and dietary administrations.

CONCLUSION

TJ-28 conspicuously reduced congestion of lymph fluid. This is the first histopathological evaluation of LM model mice to study the effectiveness of oral TJ-28 treatment.

Severe adverse events during sirolimus "off-label" therapy for vascular anomalies

OBJECTIVES

Clinical studies have shown low toxicity and a favorable safety profile for sirolimus in vascular anomalies. Here, we describe severe adverse events (SAEs) observed during "off-label use" for vascular anomalies.

METHODS

We performed a retrospective, multicenter chart review for SAEs during "off-label" sirolimus therapy for vascular anomalies and analyzed these cases by a predesigned workflow.

RESULTS

We identified 17 SAEs in 14 patients diagnosed with generalized lymphatic anomaly (n = 4), Gorham-Stout disease (n = 2), central conducting lymphatic anomaly (n = 1), lymphatic malformation (n = 4), tufted angioma (n = 1), kaposiform hemangioendothelioma (n = 1), and venous malformation in a patient with CLOVES syndrome (n = 1). Three patients presented two SAEs each. The age at initiation of sirolimus therapy was under 2 years (n = 5), 2-6 years (n = 5), and older than 12 years (n = 4). SAEs occurred during the first 3 months of sirolimus therapy (n = 7), between 3 and 12 months (n = 7) and after 1 year of therapy (n = 3). The most frequent SAE was viral pneumonia (n = 8) resulting in one death due to a metapneumovirus infection in a 3 months old and a generalized adenovirus infection in a 28-month-old child. Sirolimus blood level at the time of SAEs ranged between 2.7 and 21 ng/L. Five patients were on antibiotic prophylaxis.

CONCLUSIONS

Most SAEs are observed in the first year of sirolimus therapy; however, SAEs can also occur after a longer treatment period. SAEs are potentially life threatening, especially in early infancy. Presence of other risk factors, that is, underlying vascular anomaly or immune status, may contribute to the risk of SAEs. Sirolimus is an important therapeutic option for vascular anomalies, but patients and physicians need to be aware that adequate monitoring is necessary, especially in patients with complex lymphatic anomalies that are overrepresented in our cohort of SAEs.

Refractory Head and Neck Lymphatic Malformation in Infants Treated With Sirolimus: A Case Series

Background

Extensive and complex head and neck lymphatic malformations (LMs) are challenging to manage through traditional therapy. The purpose of this retrospective study was to assess the efficacy and safety of sirolimus in infants with refractory head and neck LMs.

Methods

Sirolimus was administered orally on a continuous dosing schedule. Patients were seen every month for the first three months and then subsequently every three months. The primary endpoints were safety and efficacy based on clinical and radiological evaluations.

Results

Eight patients, refractory to standard care, were enrolled and received sirolimus continuously. After 12 months of follow-up, the response and safety to medication was evaluated: all patients experienced reductions in LMs bulk, ranging from modest to significant. Some minor adverse effects were reported: mouth sores, eczema, gastrointestinal reaction, dyslipidemia, and neutropenia.

Conclusion

Sirolimus was efficient in children with refractory head and neck LMs and was well tolerated.

A review of mechanisms of disease across PIK3CA-related disorders with vascular manifestations

BACKGROUND

PIK3CA-related disorders include vascular malformations and overgrowth of various tissues that are caused by postzygotic, somatic variants in the gene encoding phosphatidylinositol-3-kinase (PI3K) catalytic subunit alpha. These mutations result in activation of the PI3K/AKT/mTOR signaling pathway. The goals of this review are to provide education on the underlying mechanism of disease for this group of rare conditions and to summarize recent advancements in the understanding of, as well as current and emerging treatment options for PIK3CA-related disorders.

MAIN BODY

PIK3CA-related disorders include PIK3CA-related overgrowth spectrum (PROS), PIK3CA-related vascular malformations, and PIK3CA-related nonvascular lesions. Somatic activating mutations (predominantly in hotspots in the helical and kinase domains of PIK3CA, but also in other domains), lead to hyperactivation of the PI3K signaling pathway, which results in abnormal tissue growth. Diagnosis is complicated by the variability and overlap in phenotypes associated with PIK3CA-related disorders and should be performed by clinicians with the required expertise along with coordinated care from a multidisciplinary team. Although tissue mosaicism presents challenges for confirmation of PIK3CA mutations, next-generation sequencing and tissue selection have improved detection. Clinical improvement, radiological response, and patient-reported outcomes are typically used to assess treatment response in clinical studies of patients with PIK3CA-related disorders, but objective assessment of treatment response is difficult using imaging (due to the heterogeneous nature of these disorders, superimposed upon patient growth and development). Despite their limitations, patient-reported outcome tools may be best suited to gauge patient improvement. New therapeutic options are needed to provide an alternative or supplement to standard approaches such as surgery and sclerotherapy. Currently, there are no systemic agents that have regulatory approval for these disorders, but the mTOR inhibitor sirolimus has been used for several years in clinical trials and off label to address symptoms. There are also other agents under investigation for PIK3CA-related disorders that act as inhibitors to target different components of the PI3K signaling pathway including AKT (miransertib) and PI3K alpha (alpelisib).

CONCLUSION

Management of patients with PIK3CA-related disorders requires a multidisciplinary approach. Further results from ongoing clinical studies of agents targeting the PI3K pathway are highly anticipated.

[Clinical features of Kasabach-Merritt syndrome: an analysis of 16 neonates]

OBJECTIVE

To study the clinical features, treatment, and prognosis of neonates with Kasabach-Merritt syndrome (KMS), and to provide a reference for optimizing the diagnosis and treatment of this disease.

METHODS

A retrospective analysis was performed for the clinical and follow-up data of 16 neonates with KMS who were admitted to the Anhui Children's Hospital, Anhui Medical University, from January 2016 to December 2020.

RESULTS

Of the 16 neonates, there were 13 boys (81%) and 3 girls (19%), with an age of 1 hour to 10 days on admission. Among these neonates, 13 (81%) had cutaneous hemangioma (2 in the head and face, 5 in the trunk, and 6 in the extremities) and 3 (19%) had liver hemangioma. The main clinical manifestations of bleeding tendency and scattered petechiae and ecchymosis were observed in 10 neonates (62%). All the 16 neonates had varying degrees of thrombocytopenia and coagulation disorders. They all received glucocorticoid treatment after admission and 7 (44%) of them had response, among whom 4 experienced recurrence. Among the neonates with no response to glucocorticoid treatment, 3 received sirolimus treatment, among whom 1 had the tumor volume reduced by 58.8% after 4 weeks of treatment, with platelet count and coagulation function returning to normal, while 2 had no significant reduction in tumor volume or significant increase in platelet count and achieved a tumor volume reduced by (43.7±0.4)% after 4 weeks of combined treatment with bleomycin arterial embolization, with platelet count and coagulation function returning to normal. After 4 weeks of bleomycin arterial embolization alone for 4 neonates, tumor volume was reduced by (52.0±3.4)%, and platelet count and coagulation function returned to normal. Blunt and sharp dissection was performed for 2 neonates. The tumor was removed completely during surgery in the 2 neonates, with no infection or recurrence after surgery, and platelet count and coagulation function returned to normal. The postoperative pathological examination showed Kaposiform hemangioendothelioma in 1 out of the 2 neonates.

CONCLUSIONS

KMS has characteristic clinical manifestations, histopathological features, and laboratory examination results. The KMS neonates who are not sensitive to glucocorticoids can achieve a good curative effect through arterial embolization and sirolimus treatment.

Genetic Basis and Therapies for Vascular Anomalies

Vascular and lymphatic malformations represent a challenge for clinicians. The identification of inherited and somatic mutations in important signaling pathways, including the PI3K (phosphoinositide 3-kinase)/AKT (protein kinase B)/mTOR (mammalian target of rapamycin), RAS (rat sarcoma)/RAF (rapidly accelerated fibrosarcoma)/MEK (mitogen-activated protein kinase kinase)/ERK (extracellular signal-regulated kinases), HGF (hepatocyte growth factor)/c-Met (hepatocyte growth factor receptor), and VEGF (vascular endothelial growth factor) A/VEGFR (vascular endothelial growth factor receptor) 2 cascades has led to the evaluation of tailored strategies with preexisting cancer drugs that interfere with these signaling pathways. The era of theranostics has started for the treatment of vascular anomalies. Registration: URL: https://www.clinicaltrialsregister.eu; Unique identifier: 2015-001703-32.

Lymphatic Malformations: Genetics, Mechanisms and Therapeutic Strategies

Lymphatic vessels maintain tissue fluid homeostasis by returning to blood circulation interstitial fluid that has extravasated from the blood capillaries. They provide a trafficking route for cells of the immune system, thus critically contributing to immune surveillance. Developmental or functional defects in the lymphatic vessels, their obstruction or damage, lead to accumulation of fluid in tissues, resulting in lymphedema. Here we discuss developmental lymphatic anomalies called lymphatic malformations and complex lymphatic anomalies that manifest as localized or multifocal lesions of the lymphatic vasculature, respectively. They are rare diseases that are caused mostly by somatic mutations and can present with variable symptoms based upon the size and location of the lesions composed of fluid-filled cisterns or channels. Substantial progress has been made recently in understanding the molecular basis of their pathogenesis through the identification of their genetic causes, combined with the elucidation of the underlying mechanisms in animal disease models and patient-derived lymphatic endothelial cells. Most of the solitary somatic mutations that cause lymphatic malformations and complex lymphatic anomalies occur in genes that encode components of oncogenic growth factor signal transduction pathways. This has led to successful repurposing of some targeted cancer therapeutics to the treatment of lymphatic malformations and complex lymphatic anomalies. Apart from the mutations that act as lymphatic endothelial cell-autonomous drivers of these anomalies, current evidence points to superimposed paracrine mechanisms that critically contribute to disease pathogenesis and thus provide additional targets for therapeutic intervention. Here, we review these advances and discuss new treatment strategies that are based on the recently identified molecular pathways.

Chylous content might determine the optimal surgical approach for mesenteric lymphatic malformations in childhood

BACKGROUND

Mesenteric lymphatic malformations (LMs) represent rare congenital anomalies that can include chylous or nonchylous content. The pathologic mechanisms explaining this phenomenon are poorly understood and not yet described. Furthermore, the current management approach does not consider the contents of the mesenteric LMs. In the present study, we have defined the relationship between the lymphatic mesenteric cyst content and the histologic evidence of LMs within the bowel wall.

METHODS

We retrospectively investigated all patients with mesenteric LMs treated surgically at our department from 1999 to 2018.

RESULTS

A total of 11 patients (6 girls and 5 boys) were included in our analysis. Seven patients had presented with LMs located in the jejunal mesentery, three in the ileocecal region, and only one in the mesocolon transversum and omentum. Of the 11 children, 7 had had LMs with nonchylous content and 4 had presented with chylous content LMs. Intestinal resection was performed in all 4 patients with chylous content LMs and 4 patients with nonchylous content LMs. Histopathologic evaluation of the surgical specimens determined that only the LMs with chylous content displayed malformed lymphatic channels throughout the bowel wall. The resected small bowel of four patients with nonchylous content showed no LM extension throughout the intestinal wall.

CONCLUSIONS

LMs with chylous content seem to develop from malformed lymphatic channels within the bowel wall. In such cases, segmental intestinal resection is mandatory. In contrast, mesenteric LMs with nonchylous content can potentially be treated without bowel resection if the blood supply can be preserved. This finding is, to the best of our knowledge, reported in the present study for the first time.

Vascular anomalies of the head and neck: diagnosis and treatment

Vascular malformations and vascular tumors comprise the two specific subsets of vascular anomalies that arise as a result of disorganized angiogenesis and neoplasm, respectively. Malformations are separate entities from vascular tumors (e.g., hemangiomas) and are recognized by the International Society for the Study of Vascular Anomalies (ISSVA) as such. Vascular malformations are classified into four main groups: simple, combined, anomalies of major vessels, and those associated with other vascular anomalies. Vascular tumors are neoplastic growths of blood vessels and are morphologically and molecularly distinct from malformations but can arise in the head and neck and have syndromic association. Head and neck vascular anomalies are not uncommon in the pediatric population and require special care in the workup, diagnostic imaging and clinical care. The purpose of this manuscript is to discuss the diagnosis and management of the most common intracranial and extracranial vascular malformations and tumors in the head and neck in children and adolescents.

Patients with Congenital Low-Flow Vascular Malformation Treated with Low Dose Sirolimus

INTRODUCTION

Patients with congenital vascular malformations often suffer from an impaired quality of life (QoL) because of pain and functional disabilities. Previous studies have shown that the mTOR inhibitor sirolimus can reduce complaints and improve QoL in some patients. High target levels of sirolimus of 10-15 ng/ml were well tolerated; however, in a relative high percentage of patients sirolimus caused serious adverse events (AEs).

METHODS

A case series of 12 patients with therapy-resistant low-flow vascular malformations was treated with sirolimus, using low target levels of 4-10 ng/ml. Efficacy of sirolimus was evaluated in regard to pain symptoms using the visual analogue scale/numeric rating scale and patients reported QoL. To rule out a placebo effect of sirolimus, sirolimus was stopped after a certain time point and reintroduced as soon as complaints returned. Adverse events were closely monitored and graded using the Common Terminology Criteria for Adverse Events (CTCAE) grading.

RESULTS

An improvement in symptoms was seen in 92% (n = 11/12) of patients. In nine patients pain complaints returned. Seven out of nine of them (78%) again experienced a reduction of symptoms after restarting sirolimus treatment. Despite low target levels, these response rates are comparable to those found in the literature using higher target levels of sirolimus. However, significantly less serious AEs were observed with low dose sirolimus, suggesting low dose sirolimus might be safer. Unfortunately, young adolescent female patients developed serious menstrual disturbances during treatment with low dose sirolimus. We describe this adverse event for the first time in patients with congenital vascular malformations and this might be specifically related to low dose sirolimus.

CONCLUSIONS

Low dose sirolimus showed a high efficacy in patients with therapy-resistant and low-flow malformation, with a lower incidence of serious adverse events. At the same time a new adverse event, namely menstrual cycle disturbance, was observed in young adolescents, indicating the need for caution when sirolimus is given. This is extremely relevant to patients with low-flow vascular malformation, who are likely to require lifelong treatment for their condition.

Novel treatment of recurrent orbital venolymphatic malformation with sirolimus and rivaroxaban

Orbital venolymphatic malformations are rare vascular malformations that typically appear early in life and harbor acute and chronic threats to vision. Historically, there are four categories of management: observation, medication, sclerotherapy, and surgery. Currently, there is neither a gold standard for treatment nor randomized control trials comparing treatments.The authors present a 20-year-old male who presented with spontaneous hemorrhage of an orbital venolymphatic malformation occurring with increased frequency and involving more of the posterior orbit. Surgery and sclerotherapy were not feasible options due to the extensive intraorbital and intracranial involvement of the venolymphatic malformation. Systemic steroids treated symptoms but was not curative. To this end, a combination of sirolimus, an mTOR inhibitor, and rivaroxaban, a factor Xa inhibitor, were used to reduce the size of the lesion and minimize the risk of thromboembolic events. This treatment has successfully kept the patient's symptoms in remission for greater than 2 years.

CLOVES Syndrome Diagnosis and Treatment in an Adult Patient

CLOVES syndrome is a rare, nonheritable sporadic overgrowth disorder. In the world 130-200 cases have been reported. This is the first case of CLOVES described in Portugal, which had been not been diagnosed for the last 36 years. With this paper, the authors look to highlight the clinical features of this syndrome so that it does not go unrecognized in daily practice. The authors also underline the efficacy and safety of sirolimus, and that this treatment should not be denied, even in adult patients.

Effects of sirolimus in the treatment of unresectable infantile hemangioma and vascular malformations in children: A single-center experience

OBJECTIVE

Recently, sirolimus has emerged as a safe and effective treatment modality for unresectable vascular lesions. In the present study, we investigated the effectiveness and safety of sirolimus from our early experience with patients with unresectable vascular anomalies.

METHODS

The medical records and radiologic images of all patients with unresectable vascular anomalies treated with sirolimus at our center from January 2018 to November 2019 were retrospectively reviewed. All patients were administered oral doses of sirolimus 0.8 mg/m² every 12 hours as the initial dose, followed by maintenance of a target serum concentration (5-10 ng/mL) with therapeutic drug monitoring.

RESULTS

Six patients with unresectable vascular anomalies were treated with sirolimus for ≥10 months. Their median age at the initiation of sirolimus treatment was 17 months (range, 8-67 months). The median duration of treatment was 13 months (range, 10-16 months). One patient had a good response, four had an intermediate response, and one had no response to sirolimus therapy. None of the patients had discontinued sirolimus therapy because of adverse effects.

CONCLUSIONS

Sirolimus can be used effectively and safely for patients with unresectable vascular anomalies. However, further prospective studies are warranted to evaluate the long-term effects of sirolimus and clarify the indications for early intervention.

Clinical Assessment and Lesion-Specific Management of Orbital Vascular Malformations

The systematic classification of vascular disease as proposed and refined by the International Society for the Study of Vascular Anomalies (ISSVA) divides vascular pathology first into tumors and malformations. Malformations are described as simple and complex, where simple malformations contain a single vascular system and complex malformations comprised of multiple vascular systems. Arteriovenous malformations are considered in terms of inflow characteristics which are primarily responsible for the key management challenges. Management utilizing endovascular embolization and/or surgical resection is often employed; however, recurrence can occur, particularly in diffuse cases. There may be an increasing role for systemic antiangiogenic therapy in such cases. Lymphaticovenous malformations are divided into the principle components on the lymphatic and venous sides for clarity of discussion. Lymphatic malformations are described morphologically as macrocystic and microcystic, and physiologically in terms of the processes responsible for growth. In both cases, surgical options are challenging and local therapeutics intended to close large luminal spaces in the case of macrocystic and to slow biological signaling for growth in microcystic. Venous malformations are described physiologically in terms of flow and distensibility, as volume plays a critical role in the limited space of the orbital cavity. Combined embolic-surgical approaches can be effective for management. More complicated, combined lesions can be managed by dividing the lesion into principal components and treating each appropriately.

The Use of Sirolimus for Treatment of Orbital Lymphatic Malformations: A Systematic Review

PURPOSE

Orbital lymphatic malformations are rare congenital choristomas associated with pain, proptosis, exposure keratopathy, and vision loss. Current treatments of surgery, drainage, and sclerotherapy may have adverse effects including risk of damage to surrounding structures, swelling, and malformation persistence or recrudescence. Sirolimus, which inhibits mammalian target of rapamycin, a regulator of cell growth and vascular endothelial growth factor expression, has successfully treated systemic vascular malformations. However, its efficacy and safety have not yet been well established for orbital lymphatic malformations.

METHODS

Systematic review and analysis of relevant published literature were performed. PubMed, Embase, and World of Science searches were conducted for studies involving sirolimus treatment of orbital lymphatic malformations through July 2019.

RESULTS

Nine case series and reports with 10 total patients who received sirolimus for treatment of orbital lymphatic malformations were included. The age at sirolimus initiation ranged from 1 week to 23 years. The malformation was lymphatic in 6 patients, lymphaticovenous in 3 patients, and lymphatic-arteriovenous in 1 patient. Six patients underwent ineffective prior therapy including sclerotherapy, surgery, or medical therapy. Initial sirolimus dosage ranged from 0.05 mg/kg twice a day to 1 mg twice a day, and duration ranged from 6 months to 53 months. Seven patients had partial response, and 3 patients, all of whom had a microcystic malformation component, experienced complete response. Adverse effects included mild reversible leukopenia, hypertriglyceridemia, hypercholesterolemia, and transaminitis with adverse effects denied or not specified for 6 patients.

CONCLUSIONS

Sirolimus may be a safe and effective treatment for orbital lymphatic malformations, especially microcystic malformations.

A narrative review of the role of sirolimus in the treatment of congenital vascular malformations

OBJECTIVE

Vascular malformations arise from defects in the morphologic development of the vascular system and can have an impact on quality of life and/or lead to severe complications. To date, vascular malformations are frequently managed by invasive techniques, after which recurrence is common. Sirolimus, a downstream inhibitor of the phosphatidylinositol 3 kinase/AKT pathway and best known for its immunosuppressive effect, has been used off-label for lesions for which approved therapies were associated with unsatisfactory results or recurrence. The aim of this study was to review the available data on the effect of sirolimus on the size and symptoms of different types of malformations and to summarize the main safety issues.

METHODS

A literature search in Pubmed, Embase, Web of Science, and SCOPUS was performed. Case reports, case series, and clinical trials evaluating the effect of sirolimus in vascular malformations were eligible for this review. Fully terminated studies published between January 2010 and May 2019 reporting an evaluable response on size and/or symptoms were included. Relevant data on lesion size, symptoms, side effects and duration of treatment were extracted as reported in the study. Additionally, we reported 10 unpublished cases who were treated in UZ Leuven.

RESULTS

The literature review included 68 articles, describing 324 patients. The median duration of therapy was 12 months (range, 1-60 months). After 6 months of treatment, the size of the malformation had at least decreased in 67% of patients with common venous malformations (VM), in 93% of patients with blue rubber bleb nevus syndrome and in all patients with verrucous VM. The size of lymphatic malformations improved in more than 80% of the patients, even in the case of extensive involvement such as in Gorham-Stout disease and generalized lymphatic anomaly. In addition, the majority of patients with syndromic vascular malformations experienced a decrease in size and reported symptoms improved in almost all patients, regardless of the type of malformation. Side effects were common (53%) but usually mild; mucositis and bone marrow suppression were the most common. Regrowth or recurrence of symptoms occurred in 49% of patients who discontinued treatment. Comparable effects were seen in our own patients.

CONCLUSIONS

This review shows that sirolimus is effective in decreasing the size and/or symptoms of particularly lymphatic malformations as well as VMs. Although common, side effects were usually mild. Nevertheless, clinical trials are needed to confirm the safety and effectivity of sirolimus and to identify the required serum levels and duration of treatment.