Successful management of an arteriovenous malformation with trametinib in a patient with capillary-malformation arteriovenous malformation syndrome and cardiac compromise

Covered stent combined with embolization treatment for complex congenital lower limb arteriovenous malformations: case report and literature review

BACKGROUND

Currently, the treatment outcomes for complex congenital arteriovenous malformations (AVMs) remain unsatisfactory. This article reports on the utilization of an abdominal aortic stent graft, in conjunction with embolization techniques, for managing acute heart failure triggered by complex congenital arteriovenous malformations in the lower limb.

CASE PRESENTATION

We present a case involving a patient with congenital AVMs in the lower limb, who had suffered from prolonged swelling in the left lower limb and recently developed symptoms of heart failure. At the age of 67, the patient was definitively diagnosed with a complex congenital AVMs in the lower limb. This article delves into the practical experiences and limitations encountered in employing an abdominal aortic stent graft, coupled with embolization, to address acute heart failure caused by complex congenital AVMs in the lower limb.

CONCLUSIONS

Our article presents the initial report on the challenges and limitations encountered in treating acute heart failure triggered by complex congenital AVMs in the lower limb, utilizing a combination of abdominal aortic stent graft placement and embolization techniques.

Cobb syndrome effectively treated with trametinib

Cobb syndrome is a rare neurocutaneous disease characterized by vascular anomalies involving the skin and spinal cord at the same metamere. The most common initial symptoms are neurological manifestations such as pain, monoparesis, headache, scoliosis, and motor damage. We present two patients with Cobb syndrome and severe disease burden harboring somatic mutations in KRAS. The two patients were subsequently treated with the MEK inhibitor trametinib, indicating the potential therapeutic benefit of this treatment for patients with life-threatening Cobb syndrome who are currently considered incurable.

Reverse repurposing: Potential utility of cancer drugs in nonmalignant illnesses

Growth and immune process dysregulation can result in both cancer and nonmalignant disease (hereditary or acquired, with and without predisposition to malignancy). Moreover, perhaps unexpectedly, many nonmalignant illnesses harbor genomic alterations indistinguishable from druggable oncogenic drivers. Therefore, targeted compounds used successfully to treat cancer may have therapeutic potential for nonmalignant conditions harboring the same target. MEK, PI3K/AKT/mTOR, fibroblast growth factor receptor (FGFR), and NRG1/ERBB pathway genes have all been implicated in both cancer and noncancerous conditions, and several cognate antagonists, as well as Bruton's tyrosine kinase inhibitors, JAK inhibitors, and CD20-directed antibodies, have established or theoretical therapeutic potential to bridge cancer and benign diseases. Intriguingly, pharmacologically tractable cancer drivers characterize a wide spectrum of disorders without malignant potential, including but not limited to Alzheimer's disease and a variety of other neurodegenerative conditions, rheumatoid arthritis, achondroplastic dwarfism, and endometriosis. Expanded repositioning of oncology agents in order to benefit benign but serious medical illnesses is warranted.

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.

Spontaneous multifocal pyogenic granulomas

Cutaneous pyogenic granulomas (PGs) are common, benign vascular tumors of uncertain pathogenesis; however, a growing body of literature suggests that the formation of PGs may be secondary to genetic alterations in both the Ras/Raf/MAPK and PI3K/Akt/mTOR pathways. We present three cases of spontaneous multifocal PGs that first presented in infancy, were not associated with other vascular anomalies or discernable etiology, harbored somatic genetic variants in the Ras/Raf/MAPK pathway (NRAS n = 2, FGFR1 n = 1), were refractory to treatment with beta-blockers and mTOR inhibitors, and responded best to pulsed dye laser. We propose the term "spontaneous multifocal PGs" to describe this entity.

Congenital Vascular and Lymphatic Diseases

Over the past several centuries, the integration of contemporary medical techniques and innovative technologies, like genetic sequencing, have played a pivotal role in enhancing our comprehension of congenital vascular and lymphatic disorders. Nonetheless, the uncommon and complex characteristics of these disorders, especially considering their formation during the intrauterine stage, present significant obstacles in diagnosis and treatment. Here, we review the intricacies of these congenital abnormalities, offering an in-depth examination of key diagnostic approaches, genetic factors, and therapeutic methods.

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.

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

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

Capillary malformations

Capillary malformation (CM), or port wine birthmark, is a cutaneous congenital vascular anomaly that occurs in 0.1%-2% of newborns. Patients with a CM localized on the forehead have an increased risk of developing a neurocutaneous disorder called encephalotrigeminal angiomatosis or Sturge-Weber syndrome (SWS), with complications including seizure, developmental delay, glaucoma, and vision loss. In 2013, a groundbreaking study revealed causative activating somatic mutations in the gene (GNAQ) encoding guanine nucleotide-binding protein Q subunit α (Gαq) in CM and SWS patient tissues. In this Review, we discuss the disease phenotype, the causative GNAQ mutations, and their cellular origin. We also present the endothelial Gαq-related signaling pathways, the current animal models to study CM and its complications, and future options for therapeutic treatment. Further work remains to fully elucidate the cellular and molecular mechanisms underlying the formation and maintenance of the abnormal vessels.

Medical Therapeutics for the Treatment of Vascular Anomalies: Part 3

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

Updates in Genetic Testing for Head and Neck Vascular Anomalies

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

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Etiologies of Brain Arteriovenous Malformation Recurrence: A Focus on Pediatric Disease

Pediatric brain arteriovenous malformations are a major cause of morbidity and mortality, with the harmful effects of this disease compounded by the additional disability-years experienced by children with ruptured or other symptomatic arteriovenous malformations. In addition to the risks shared with their adult counterparts, pediatric patients frequently experience recurrence following radiographic cure, which presents an additional source of morbidity and mortality. Therefore, there is a need to synthesize potential mechanisms contributing to the elevated recurrence risk in the pediatric population and discuss how these translate to practical considerations for managing these patients.

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.

Intramuscular capillary-type hemangioma: Diagnosis, treatment, and outcomes. A French multicentric retrospective study of 66 cases

PURPOSE

Intramuscular capillary-type hemangiomas (ICTHs) are rare entities, belonging to the group of intramuscular "hemangiomas." The diagnosis remains challenging. We aimed to assess the diagnostic criteria, treatments and outcomes of ICTHs.

METHODS

This retrospective study collected all cases of ICTH followed up in 9 French hospital centers, reviewed by an adjudication expert group.

RESULTS

Among 133 patients screened, 66 with ICTH were included. The median age of patients at diagnosis was 28.0 years, interquartile range (21.0---36.0). The lesion, mainly presenting as a gradually increasing mass (83.9%), was painless (88.9%) and was located in the head and neck (42.4%). MRI (available in all cases) mainly revealed a well-delineated lesion, isointense to the muscle on T1-weighted images, with enhancement after contrast injection; hyperintense on T2-weighted images; and containing flow voids. Among the 66 cases, 59 exhibited typical ICTH features and 7 shared some imaging features with arteriovenous malformations. These latter were larger than typical ICTHs and more painful and appeared on imaging as less well delimited and more heterogeneous tissue masses, with larger tortuous afferent arteries, earlier draining vein opacification and mild arteriovenous shunting. We propose to name these lesions arteriovenous malformation (AVM)-like ICTH. Pathological reports were similar in typical and AVM-like ICTH, showing capillary proliferation with mainly small-size vessels, negative for GLUT-1 and positive for ERG, AML, CD31 and CD34, with low Ki67 proliferation index (<10%), and adipose tissue. The most frequent treatment for ICTH was complete surgical resection (17/47, 36.2%), preceded in some cases by embolization, which led to complete remission.

CONCLUSIONS

ICTH can be diagnosed on MRI when it is typical. Biopsy or angiography are required for atypical forms.

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.

Characteristics, Natural Course and Treatment of Intramuscular Capillary-type Haemangioma: A Systematic Literature Review

Intramuscular capillary-type haemangiomas (ICTH) are rare vascular anomalies that can easily be misdiagnosed as other entities. A systematic review was performed of all cases of ICTH in the literature since its first description in 1972. An adjudication committee reviewed cases to include only ICTHs. Among 1,143 reports screened, 43 were included, involving 75 patients. The most frequent differential diagnosis was intramuscular venous malformations. The mean age of patients at diagnosis was 21.2 years. ICTH was mainly described as a gradually increasing mass (81.8%), painless (73.9%), that could occur anywhere in the body but most frequently on the head and neck (44.0%). Magnetic resonance imaging (MRI) was mainly used for diagnosis (69.1%) and displayed specific features. The most frequent treatment was complete surgical removal (73.9%), which could be preceded by embolization, and led to complete remission without recurrence in all but 1 case.

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.

Trametinib as a promising therapeutic option in alleviating vascular defects in an endothelial KRAS-induced mouse model

Somatic activating Kirsten rat sarcoma viral oncogene homologue (KRAS) mutations have been reported in patients with arteriovenous malformations. By producing LSL-Kras (G12D); Cdh5 (PAC)-CreERT2 [iEC-Kras (G12D*)] mice, we hoped to activate KRAS within vascular endothelial cells (ECs) to generate an arteriovenous malformation mouse model. Neonatal mice were treated daily with tamoxifen from postnatal (PN) days 1-3. Mortality and phenotypes varied amongst iEC-Kras (G12D*) pups, with only 31.5% surviving at PN14. Phenotypes (focal lesions, vessel dilations) developed in a consistent manner, although with unpredictable severity within multiple soft tissues (such as the brain, liver, heart and brain). Overall, iEC-Kras (G12D*) pups developed significantly larger vascular lumen areas compared with control littermates, beginning at PN8. We subsequently tested whether the MEK inhibitor trametinib could effectively alleviate lesion progression. At PN16, iEC-Kras (G12D*) pup survival improved to 76.9%, and average vessel sizes were closer to controls than in untreated and vehicle-treated mutants. In addition, trametinib treatment helped normalize iEC-Kras (G12D*) vessel morphology in PN14 brains. Thus, trametinib could act as an effective therapy for KRAS-induced vascular malformations in patients.

Clinical Outcome and Quality of Life of Multimodal Treatment of Extracranial Arteriovenous Malformations: The APOLLON Study Protocol

PURPOSE

Arteriovenous malformations (AVMs) as rare diseases are diagnostically and therapeutically challenging. Due to the limited evidence regarding treatment outcome, prospective data are needed on how different treatment regimens affect outcome. The aims of this prospective trial are to determine effectiveness, safety, and clinical outcome of multimodal treatment in patients with extracranial AVMs.

MATERIALS AND METHODS

After clinical and magnetic resonance imaging (MRI)-based diagnosis and informed consent, 146 patients (> 4 years and < 70 years) undergoing multimodal therapy in tertiary care vascular anomalies centers will be included in this prospective observational trial. Treatment options include conservative management, medical therapy, minimally invasive image-guided procedures (embolization, sclerotherapy) and surgery as well as combinations of the latter. The primary outcome is the patient-reported QoL 6 months after completion of treatment using the short form-36 health survey version 2 (SF-36v2) and the corresponding short form-10 health survey (SF-10) for children. In addition, clinical presentation (physician-reported signs), MRI imaging (radiological assessment of devascularization), recurrence rate, and therapeutic safety will be analyzed. Further follow-up will be performed after 12, 24, and 36 months. Moreover, liquid biopsies are being obtained from peripheral blood at multiple time points to investigate potential biomarkers for therapy response and disease progression.

DISCUSSION

The APOLLON trial is a prospective, multicenter, observational open-label trial with unequal study groups to generate prospective evidence for multimodal treatment of AVMs. A multicenter design with the potential to assess larger populations will provide an increased understanding of multimodal therapy outcome in this orphan disease.

TRIAL REGISTRATION

German Clinical Trials Register (identification number: DRKS00021019) https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021019 .

Hypoxia Promotes Angiogenic Effect in Extracranial Arteriovenous Malformation Endothelial Cells

Arteriovenous malformation (AVM) is characterized by high-flow blood vessels connecting arteries and veins without capillaries. This disease shows increased angiogenesis and a pathophysiological hypoxic environment in proximal tissues. Here, we analyzed the effects of hypoxia on angiogenesis in the endothelial cells (ECs) of AVM and normal tissues. ECs from human normal and AVM tissues were evaluated using immunocytochemistry with CD31. In vitro tube formation under hypoxia was tested in both ECs using Matrigel. The relative expression of angiogenesis-related genes was measured using real-time PCR. Under normoxia, CD31 was significantly higher in AVM ECs (79.23 ± 0.65%) than in normal ECs (74.15 ± 0.70%). Similar results were observed under hypoxia in AVM ECs (63.85 ± 1.84%) and normal ECs (60.52 ± 0.51%). In the tube formation test under normoxic and hypoxic conditions, the junction count and total vessel length were significantly greater in AVM ECs than normal ECs. Under both normoxia and hypoxia, the angiogenesis-related gene FSTL1 showed a significantly higher expression in AVM ECs than in normal ECs. Under hypoxia, CSPG4 expression was significantly lower in AVM ECs than in normal ECs. Accordingly, the angiogenic effect was increased in AVM ECs compared with that in normal ECs. These results provide a basic knowledge for an AVM treatment strategy.