Induced Endothelial Cell Cycle Arrest Prevents Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Distinct endothelial cell cycle states (early G1 versus late G1) provide different "windows of opportunity" to enable the differential expression of genes that regulate venous versus arterial specification, respectively. Endothelial cell cycle control and arteriovenous identities are disrupted in vascular malformations including arteriovenous shunts, the hallmark of hereditary hemorrhagic telangiectasia (HHT). To date, the mechanistic link between endothelial cell cycle regulation and the development of arteriovenous malformations (AVMs) in HHT is not known.

METHODS

We used BMP (bone morphogenetic protein) 9/10 blocking antibodies and endothelial-specific deletion of activin A receptor like type 1 (Alk1) to induce HHT in Fucci (fluorescent ubiquitination-based cell cycle indicator) 2 mice to assess endothelial cell cycle states in AVMs. We also assessed the therapeutic potential of inducing endothelial cell cycle G1 state in HHT to prevent AVMs by repurposing the Food and Drug Administration-approved CDK (cyclin-dependent kinase) 4/6 inhibitor (CDK4/6i) palbociclib.

RESULTS

We found that endothelial cell cycle state and associated gene expressions are dysregulated during the pathogenesis of vascular malformations in HHT. We also showed that palbociclib treatment prevented AVM development induced by BMP9/10 inhibition and Alk1 genetic deletion. Mechanistically, endothelial cell late G1 state induced by palbociclib modulates the expression of genes regulating arteriovenous identity, endothelial cell migration, metabolism, and VEGF-A (vascular endothelial growth factor A) and BMP9 signaling that collectively contribute to the prevention of vascular malformations.

CONCLUSIONS

This study provides new insights into molecular mechanisms leading to HHT by defining how endothelial cell cycle is dysregulated in AVMs because of BMP9/10 and Alk1 signaling deficiencies, and how restoration of endothelial cell cycle control may be used to treat AVMs in patients with HHT.

New genetic drivers in hemorrhagic hereditary telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disease inherited in an autosomal dominant manner. Disease-causing variants in endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1) genes are detected in around 90% of the patients; also 2% of patients harbor pathogenic variants at SMAD4 and GDF2. Importantly, the genetic cause of 8% of patients with clinical HHT remains unknown. Here, we present new putative genetic drivers of HHT.

METHODS

To identify new HHT genetic drivers, we performed exome sequencing of 19 HHT patients and relatives with unknown HHT genetic etiology. We applied a multistep filtration strategy to catalog deleterious variants and prioritize gene candidates based on their known relevance in endothelial cell biology. Additionally, we performed in vitro validation of one of the identified variants.

RESULTS

We identified variants in the INHA, HIF1A, JAK2, DNM2, POSTN, ANGPTL4, FOXO1 and SMAD6 genes as putative drivers in HHT. We have identified the SMAD6 p.(Glu407Lys) variant in one of the families; this is a loss-of-function variant leading to the activation of the BMP/TGFβ signaling in endothelial cells.

CONCLUSIONS

Variants in these genes should be considered for genetic testing in patients with HHT phenotype and negative for ACVRL1/ENG mutations.

Potential angiogenic biomarkers in hereditary hemorrhagic telangiectasia and other vascular diseases

Biomarkers are new tools framed in precision and personalized medicine. Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic vascular disease with disturbances in the angiogenic pathways. Descriptive evidence supports that some angiogenesis-related molecules are differently detected in HHT patients compared to healthy subjects. These molecules are also related to diagnosis, prognosis, complications and therapy monitoring in other common vascular diseases. Despite the need for improving knowledge before applying them in daily clinical practice, there are good candidates to be considered as potential biomarkers in HHT and other vascular diseases. In the present review, the authors aim to summarize and discuss current evidence regarding the main putative angiogenic biomarkers by describing the biological role of each biomarker, the evidence related to HHT and their potential use in this and other common vascular diseases from a clinical point-of-view.

Aflibercept for Gastrointestinal Bleeding in Hereditary Hemorrhagic Telangiectasia: A Case Report

Herein, we present the first described hereditary hemorrhagic telangiectasia (HHT) patient treated with aflibercept for severe GI involvement after tachyphylaxis to bevacizumab, with promising results. HHT is a rare genetic disease characterized by systemic vascular malformations. Gastrointestinal telangiectasia is one of the major involvements that can produce chronic severe iron-deficiency anemia. Nowadays, support treatment with iron replacement therapy, red blood cell transfusions, and antiangiogenic drugs-mainly bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF)-are the main therapeutic options for this complication. The evidence of alternative drugs in patients with failure to this approach, such as tachyphylaxis to bevacizumab, is scarce. Aflibercept is a VEGF inhibitor with antiangiogenic properties approved for the treatment of different types of cancer and ocular neovascularization diseases.

Long-term use of somatostatin analogs for chronic gastrointestinal bleeding in hereditary hemorrhagic telangiectasia

Background

Chronic bleeding due to gastrointestinal (GI) involvement in patients with hemorrhagic hereditary telangiectasia (HHT) can provoke severe anemia with high red blood cells (RBC) transfusion requirements. However, the evidence about how to deal with these patients is scarce. We aimed to assess the long-term efficacy and safety of somatostatin analogs (SA) for anemia management in HHT patients with GI involvement.

Methods

This is a prospective observational study including patients with HHT and GI involvement attended at a referral center. SA were considered for those patients with chronic anemia. Anemia-related variables were compared in patients receiving SA before and during treatment. Patients receiving SA were divided into responders (patients with minimal hemoglobin levels improvement >10 g/L and maintaining hemoglobin levels ≥80 g/L during treatment), and non-responders. Adverse effects during follow-up were collected.

Results

Among 119 HHT patients with GI involvement, 67 (56.3%) received SA. These patients showed lower minimal hemoglobin levels (73 [60-87] vs. 99 [70.2-122.5], p < 0.001), and more RBC transfusion requirements (61.2% vs. 38.5%, p = 0.014) than patients without SA therapy. Median treatment period was 20.9 ± 15.2 months. During treatment, there was a statistically significant improvement in minimum hemoglobin levels (94.7 ± 29.8 g/L vs. 74.7 ± 19.7, p < 0.001) and a reduction of patients with minimal hemoglobin levels <80 g/L (39 vs. 61%, p = 0.007) and RBC transfusions requirement (33.9% vs. 59.3%, p < 0.001). Sixteen (23.9%) patients showed mild adverse effects, mostly diarrhea or abdominal pain, leading to treatment discontinuation in 12 (17.9%) patients. Fifty-nine patients were eligible for efficacy assessment and 32 (54.2%) of them were considered responders. Age was associated with non-responder patients, OR 95% CI; 1.070 (1.014-1.130), p = 0.015.

Conclusion

SA can be considered a long-term effective and safe option for anemia management in HHT patients with GI bleeding. Older age is associated with poorer response.

Improving Hereditary Hemorrhagic Telangiectasia Molecular Diagnosis: A Referral Center Experience

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disease inherited in an autosomal dominant manner. Disease-causing variants in endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1) genes are detected in more than 90% of the patients undergoing molecular testing. The identification of variants of unknown significance is often seen as a challenge in clinical practice that makes family screening and genetic counseling difficult. Here, we show that the implementation of cDNA analysis to assess the effect of splice site variants on mRNA splicing is a powerful tool.

METHODS

Gene panel sequencing of genes associated with HHT and other arteriovenous malformation-related syndromes was performed. To evaluate the effect of the splice site variants, cDNA analysis of ENG and ACVRL1 genes was carried out.

RESULTS

three novel splice site variants were identified in ENG (c.68-2A > T and c.1311+4_1311+8del) and ACVLR1 (c.526-6C > G) genes correspondingly in three individuals with HHT that met ≥ 3 Curaçao criteria. All three variants led to an aberrant splicing inducing exon skipping (ENG:c.68-2A > T and ACVRL1:c.526-6C > G) or intron retention (ENG:c.1311+4_1311+8del) allowing the confirmation of the predicted effect on splicing and the reclassification from unknown significance to pathogenic/likely pathogenic of two of them.

CONCLUSIONS

RNA analysis should be performed to assess and/or confirm the impact of variants on splicing. The molecular diagnosis of HHT patients is crucial to allow family screening and accurate genetic counseling. A multidisciplinary approach including clinicians and geneticists is crucial when dealing with patients with rare diseases.

Translational medicine in hereditary hemorrhagic telangiectasia

Scientific community have gained lots of new insights in the genetic and biochemical background of different conditions, rare diseases included, settling the basis for preclinical models that are helping to identify new biomarkers and therapeutic targets. Translational Medicine (TM) is an interdisciplinary area of biomedicine with an essential role in bench-to-bedside transition enhancement, generating a circular flow of knowledge transference between research environment and clinical setting, always centered in patient needs. Here, we present different tools used in TM and an overview of what is being done related to hereditary hemorrhagic telangiectasia (HHT), as a disease's model. This work is focused on how this combination of basic and clinical research impacts in HHT patient's daily clinical management and also looking into the future. Further randomized clinical trials with HHT patients should assess the findings of this bench-to-bedside transition. The benefits of this basic and clinical research combination, may not only be important for HHT patients but for patients with other vascular diseases sharing angiogenic disturbances.

Catheter-Directed Therapies in Patients with Pulmonary Embolism: Predictive Factors of In-Hospital Mortality and Long-Term Follow-Up

(1) Background: Catheter-directed therapies (CDT) may be considered for selected patients with pulmonary embolism (PE); (2) Methods: Retrospective observational study including all consecutive patients with acute PE undergoing CDT (mechanical or pharmacomechanical) from January 2010 through December 2020. The aim was to evaluate in-hospital and long-term mortality and its predictive factors; (3) Results: We included 63 patients, 43 (68.3%) with high-risk PE. All patients underwent mechanical CDT and, additionally, 27 (43%) underwent catheter-directed thrombolysis. Twelve (19%) patients received failed systemic thrombolysis (ST) prior to CDT, and an inferior vena cava (IVC) filter was inserted in 28 (44.5%) patients. In-hospital PE-related and all-cause mortality rates were 31.7%; 95% CI 20.6-44.7% and 42.9%; 95% CI 30.5-56%, respectively. In multivariate analysis, age > 70 years and previous ST were strongly associated with PE-related and all-cause mortality, while IVC filter insertion during the CDT was associated with lower mortality rates. After a median follow-up of 40 (12-60) months, 11 more patients died (mortality rate of 60.3%; 95% CI 47.2-72.4%). Long-term survival was significantly higher in patients who received an IVC filter; (4) Conclusions: Age > 70 years and failure of previous ST were associated with mortality in acute PE patients treated with CDT. In-hospital and long-term mortality were lower in patients who received IVC filter insertion.

Adrenomedullin as a potential biomarker involved in patients with hereditary hemorrhagic telangiectasia

BACKGROUND

Adrenomedullin (AM) is a vasoactive peptide mostly secreted by endothelial cells with an important role in preserving endothelial integrity.  The relationship between AM and hereditary hemorrhagic telangiectasia (HHT) is unknown. We aimed to compare the serum levels and tissue expression of AM between HHT patients and controls.

METHODS

Serum AM levels were measured by radioimmunoassay and compared between control and HHT groups. AM levels were also compared among HHT subgroups according to clinical characteristics. The single nucleotide polymorphism (SNP) rs4910118 was assessed by restriction analysis and sequencing. AM immunohistochemistry was performed on biopsies of cutaneous telangiectasia from eight HHT patients and on the healthy skin from five patients in the control group.

RESULTS

Forty-five HHT patients and 50 healthy controls were included, mean age (SD) was 50.7 (14.9) years and 46.4 (9.9) years (p = 0.102), respectively. HHT patients were mostly female (60% vs 38%, p = 0.032). Median [Q1-Q3] serum AM levels were 68.3 [58.1-80.6] pg/mL in the HHT group and 47.7 [43.2-53.8] pg/mL in controls (p<0.001), with an optimal AM cut-off according to Youden's J statistic of 55.32 pg/mL (J:0.729). Serum AM levels were similar in the HHT subgroups. No patient with HHT had the SNP rs4910118. AM immunoreactivity was found with high intensity in the abnormal blood vessels of HHT biopsies.

CONCLUSIONS

We detected higher AM serum levels and tissue expression in patients with HHT than in healthy controls. The role of AM in HHT, and whether AM may constitute a novel biomarker and therapeutic target, needs further investigation.

Comparative clinical prognosis of massive and non-massive pulmonary embolism: A registry-based cohort study

AIMS

Little is known about the prognosis of patients with massive pulmonary embolism (PE) and its risk of recurrent venous thromboembolism (VTE) compared with non-massive PE, which may inform clinical decisions. Our aim was to compare the risk of recurrent VTE, bleeding, and mortality after massive and non-massive PE during anticoagulation and after its discontinuation.

METHODS AND RESULTS

We included all participants in the RIETE registry who suffered a symptomatic, objectively confirmed segmental or more central PE. Massive PE was defined by a systolic hypotension at clinical presentation (<90 mm Hg). We compared the risks of recurrent VTE, major bleeding, and mortality using time-to-event multivariable competing risk modeling. There were 3.5% of massive PE among 38 996 patients with PE. During the anticoagulation period, massive PE was associated with a greater risk of major bleeding (subhazard ratio [sHR] 1.72, 95% confidence interval [CI] 1.28-2.32), but not of recurrent VTE (sHR 1.15, 95% CI 0.75-1.74) than non-massive PE. An increased risk of mortality was only observed in the first month after PE. After discontinuation of anticoagulation, among 11 579 patients, massive PE and non-massive PE had similar risks of mortality, bleeding, and recurrent VTE (sHR 0.85, 95% CI 0.51-1.40), but with different case fatality of recurrent PE (11.1% versus 2.4%, P = .03) and possibly different risk of recurrent fatal PE (sHR 3.65, 95% CI 0.82-16.24).

CONCLUSION

In this large prospective registry, the baseline hemodynamic status of the incident PE did not influence the risk of recurrent VTE, during and after the anticoagulation periods, but was possibly associated with recurrent PE of greater severity.

Direct oral anticoagulants versus vitamin K antagonists in antiphospholipid syndrome: A meta-analysis

BACKGROUND

Anticoagulant treatment is recommended in patients with thrombosis and antiphospholipid syndrome (APS). Conflicting results have been reported on the role of direct oral anticoagulants (DOACs) in these patients. We performed a meta-analysis of randomized controlled trials (RCTs) focused on this issue.

METHODS

We searched MEDLINE and EMBASE for RCTs comparing DOACs and vitamin K antagonists (VKAs) for secondary thromboprophylaxis in patients with thrombotic APS. The primary objective was to assess the efficacy of DOACs compared to VKAs to prevent recurrence of thromboembolic events. Risk difference (RD) was reported as weighted RD according to Mantel-Haenszel random-effect method.

RESULTS

Three RCTs (426 patients) were included, all comparing rivaroxaban with VKAs. The proportion of recurrences (either arterial or venous) was higher among rivaroxaban patients when compared with those receiving VKAs (9.5% vs 2.8%; RD 6%, 95% CI, -0.05 - 0.18, p=0.29), although non-statistically significant. In patients with an arterial index event, thromboembolic recurrences were more frequent in those treated with rivaroxaban compared to those treated with VKAs (25% vs 6.2%; RD 19%, 95% CI, 0.04 - 0.33; p =0.01; I² 49%). In triple aPL positive patients, rivaroxaban showed higher rates of thromboembolic recurrences compared with VKAs (12% vs 3%; RD 9%, 95% CI, 0.02 - 0.15; p= 0.01; I² 13%). Non-statistically significant differences were observed in major bleeding events or mortality.

CONCLUSIONS

The use of rivaroxaban in APS patients is associated with an increased rate of thromboembolic recurrences compared to VKAs, at least in those with arterial index event or triple aPL positivity.

Gender differences in hereditary hemorrhagic telangiectasia severity

Background

Gender differences in organ involvement and clinical severity have been poorly described in hereditary hemorrhagic telangiectasia (HHT). The aim of this study was to describe differences in the severity of HHT manifestations according to gender.

Methods

Severity was measured according to Epistaxis Severity Score (ESS), Simple Clinical Scoring Index for hepatic involvement, a general HHT-score, needing for invasive treatment (pulmonary or brain arteriovenous malformations -AVMs- embolization, liver transplantation or Young’s surgery) or the presence of adverse outcomes (severe anemia, emergency department -ED- or hospital admissions and mortality).

Results

One hundred forty-two (58.7%) women and 100 (41.3%) men were included with a mean age of 48.9 ± 16.6 and 49 ± 16.5 years, respectively. Women presented hepatic manifestations (7.1% vs 0%) and hepatic involvement (59.8% vs 47%), hepatic AVMs (28.2% vs 13%) and bile duct dilatation (4.9% vs 0%) at abdominal CT, and pulmonary AVMs at thoracic CT (35.2% vs 23%) more often than men. The Simple Clinical Scoring Index was higher in women (3.38 ± 1.2 vs 2.03 ± 1.2), and more men were considered at low risk of harboring clinically significant liver disease than women (61% vs 25.3%). These differences were mantained when considering HHT1 and HHT2 patients separetely. Duodenal telangiectasia were more frequent in men than women (21% vs 9.8%). Invasive treatments were more frequently needed in women (28.2% vs 16%) but men needed attention at the ED more often than women (48% vs 28.2%), with no differences in ESS, HHT-score, anemia hospital admissions or mortality.

Conclusions

HHT women showed more severe hepatic involvement than men, also among HHT1 and HHT2 patients. Women had higher prevalence of pulmonary AVMs and needed invasive procedures more frequently, while men needed attention at the ED more often. These data might help physicians to individualize HHT patients follow-up.

PI3K (Phosphatidylinositol 3-Kinase) Activation and Endothelial Cell Proliferation in Patients with Hemorrhagic Hereditary Telangiectasia Type 1

Hemorrhagic hereditary telangiectasia (HHT) type 2 patients have increased activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway in telangiectasia. The main objective is to evaluate the activation of the PI3K pathway in cutaneous telangiectasia of HHT1 patients. A cutaneous biopsy of a digital hand telangiectasia was performed in seven HHT1 and eight HHT2 patients and compared with six controls. The study was approved by the Clinical Research Ethics Committee of our center. A histopathological pattern with more dilated and superficial vessels that pushed up the epidermis was identified in HHT patients regardless of the type of mutation and was associated with older age, as opposed to the common telangiectasia pattern. The mean proliferation index (Ki-67) was statistically higher in endothelial cells (EC) from HHT1 than in controls. The percentage of positive EC for pNDRG1, pAKT, and pS6 in HHT1 patients versus controls resulted in higher values, statistically significant for pNDRG1 and pS6. In conclusion, we detected an increase in EC proliferation linked to overactivation of the PI3K pathway in cutaneous telangiectasia biopsies from HHT1 patients. Our results suggest that PI3K inhibitors could be used as novel therapeutic agents for HHT.

Natural history of patients with venous thromboembolism and hereditary hemorrhagic telangiectasia. Findings from the RIETE registry

Background

Limited data exist about the clinical presentation, ideal therapy and outcomes of patients with hereditary hemorrhagic telangiectasia (HHT) who develop venous thromboembolism (VTE).

Methods

We used the data in the RIETE Registry to assess the clinical characteristics, therapeutic approaches and clinical outcomes during the course of anticoagulant therapy in patients with HHT according to initial presentation as pulmonary embolism (PE) or deep venous thrombosis (DVT).

Results

Of 51,375 patients with acute VTE enrolled in RIETE from February 2009 to January 2019, 23 (0.04%) had HHT: 14 (61%) initially presented with PE and 9 (39%) with DVT alone. Almost half (47.8%) of the patients with VTE had a risk factor for VTE. Most PE and DVT patients received low-molecular-weight heparin for initial (71 and 100%, respectively) and long-term therapy (54 and 67%, respectively). During anticoagulation for VTE, the rate of bleeding events (major 2, non-major 6) far outweighed the rate of VTE recurrences (recurrent DVT 1): 50.1 bleeds per 100 patient-years (95%CI: 21.6-98.7) vs. 6.26 recurrences (95%CI: 0.31–30.9; p = 0.020). One major and three non-major bleeding were epistaxis. No patient died of bleeding. One patient died shortly after being diagnosed with acute PE.

Conclusions

During anticoagulation for VTE in HHT patients, there were more bleeding events than VTE recurrences. Most bleeding episodes were non-major epistaxis.

Optimal duration of first-line chemotherapy for advanced gastric cancer: data from the AGAMENON registry

BACKGROUND

The optimal duration of first-line chemotherapy for patients with advanced gastric cancer is unknown. Diverse clinical trials have proposed different strategies including limited treatment, maintenance of some drugs, or treatment until progression.

METHOD

The sample comprises patients from the AGAMENON multicenter registry without progression after second evaluation of response. The objective was to explore the optimal duration of first-line chemotherapy. A frailty multi-state model was conducted.

RESULTS

415 patients were divided into three strata: discontinuation of platinum and maintenance with fluoropyrimidine until progression (30%, n = 123), complete treatment withdrawal prior to progression (52%, n = 216), and full treatment until progression (18%, n = 76). The hazard of tumor progression decreased by 19% per month with the full treatment regimen. However, we found no evidence that fluoropyrimidine maintenance (hazard ratio [HR] 1.07, confidence interval [CI] 95%, 0.69-1.65) worsened progression-free survival (PFS) with respect to treatment until progression. Predictive factors for PFS were ECOG performance status, ≥ 3 metastatic sites, prior tumor response, and bone metastases. Toxicity grade 3/4 was more common in those who continued the full treatment until progression vs fluoropyrimidine maintenance (16% vs 6%).

CONCLUSION

The longer duration of the full initial regimen exerted a protective effect on the patients of this registry. Platinum discontinuation followed by fluoropyrimidine maintenance yields comparable efficacy to treatment up to PD, with a lower rate of serious adverse events.

Risk of recurrent venous thromboembolism after acute pulmonary embolism: Role of residual pulmonary obstruction and persistent right ventricular dysfunction. A meta-analysis

Essentials Debated is the role of residual pulmonary obstruction (RPO) in predicting venous thromboembolism. Whether right ventricular dysfunction (RVD) predicts recurrent venous thromboembolism is unknown. 15 studies on RPO and 4 on RVD and venous thromboembolism were included in this meta-analysis. RPO is a predictor of recurrent venous thromboembolism when assessed by perfusion lung scan. RVD after acute pulmonary embolism is not associated with recurrent venous thromboembolism.

BACKGROUND

There is conflicting evidence regarding the role of residual pulmonary obstruction (RPO) or persistent right ventricular dysfunction (RVD) after pulmonary embolism (PE) as a predictor of recurrent venous thromboembolism (VTE). The aim of this study was to assess whether RPO or persistent RVD after PE is associated with recurrent VTE.

METHODS

MEDLINE and EMBASE were searched through December 2018. Studies reporting on (a) RPO either on computed tomography (CT) angiography or perfusion lung scan, or RVD on echocardiography or CT angiography, after therapeutic anticoagulation for the acute PE, and (b) recurrent VTE, were included in this meta-analysis.

RESULTS

RPO was associated with an increased risk of recurrent VTE (16 studies; 3472 patients; odds ratio [OR] 2.22; 95% confidence interval [CI] 1.61-3.05; I2  = 26%); the association was statistically significant for lung scan-detected RPO (11 studies; 2916 patients; OR 2.21; 95% CI 1.63-3.01) but not for CT angiography-detected RPO (five studies; 556 patients; OR 2.56; 95% CI 0.82-7.94). No significant association was found between persistent RVD and recurrent VTE (four studies; 852 patients; OR 1.62; 95% CI 0.63-4.17).

CONCLUSIONS

RPO is a predictor of recurrent VTE after a first acute PE, mainly when assessed by perfusion lung scan.