Parambil, Joseph G.

Background The current classification of pulmonary hypertension (PH), based largely on expert opinion, has limitations in prognostication and guiding therapies. We hypothesize that novel PH clusters that predict survival will reveal mechanistic phenotypes associated with biomarkers of vascular health across all PH groups. Methods We first identify novel PH clinical clusters by performing unsupervised clustering analysis on the CC‐PH (Cleveland Clinic PH) registry (N=1529). We develop classification models to predict the new PH clusters and then apply them to the multicenter PVDOMICS (Pulmonary Vascular Diseases Phenomics) cohort (N=853) for validation. We compare transplantation‐free survival across the new PH clusters. We quantify metabolites of the arginine‐nitric oxide pathway and D‐dimer levels and calculate global arginine bioavailability (arginine/[ornithine+citrulline]) to assess endothelial function and activation in the new clusters and link these biomarkers to clinical outcomes. Results Clustering analysis identify 3 clear clusters in CC ‐ PH that are validated in PVDOMICS and outperform conventional classifications in predicting transplantation‐free survival. The phenotype associated with the worst survival is characterized by reduced lung diffusion capacity, decreased arginine bioavailability and nitrate levels, and elevated D‐dimer levels, consistent with loss of pulmonary microcirculation and endothelial dysfunction. Conclusions We identify new informative PH phenotypes associated with mortality and defined by biomarkers of endothelial function and activation. Loss of endothelial health and pronounced pulmonary vascular rarefication contribute more substantially to mortality across the spectrum of PH than right heart function. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02980887.

Abstract Background Tuberous sclerosis complex (TSC) is a multisystem genetic disorder frequently associated with lymphangioleiomyomatosis (LAM), a progressive cystic lung disease. The 2022 Updated International TSC Consensus guidelines recommend clinical assessment for LAM and chest CT in all females, and symptomatic males, 18 years or older. We aimed to evaluate pulmonary screening practices along with demographic, genetic and clinical characteristics of those with TSC-LAM in a large national TSC cohort. Methods We conducted a retrospective observational study using the TSC Alliance Natural History Database. Demographic, genetic, and clinical data were extracted. Screening rates for LAM were assessed, and clinical, genetic, and pulmonary characteristics of patients diagnosed with LAM were analyzed. Results Among 2,636 patients with TSC (1,301 females, 49%), molecular testing was performed in 1,591 (60%), identifying TSC1 mutations in 349 (21.9%) and TSC2 mutations in 978 (61.5%). Screening for LAM was reported by 312 patients (11.8%; 42 (13.5%) males), of whom 116 were diagnosed with LAM; 111 (95.7%) were female. Mean age at cohort characterization was 48 years (range 21-80, SD 12.9), and mean age at LAM diagnosis (available in 82 patients) was 33 years (range 14-69, SD 12.5). Among LAM patients, molecular testing was performed in 74 (64%), TSC1 mutations were present in 8 (6.9%), TSC2 in 47 (40.5%), and dual mutations in 2. Common clinical manifestations included renal angiomyolipomas (104, 89.7%), facial angiofibromas (90, 77.6%), epilepsy (70, 60.3%), and subependymal giant cell astrocytoma (27, 23.3%). Pulmonary function data were limited (mean FEV₁ 84.9% predicted, n = 43; mean DLCO 77.6% predicted, n = 27). Serum VEGF-D available in 10 patients, range 331-9,523 pg/mL). Chest CT was performed in 87 patients (75%) and biopsy in 4 (3%). Patient-reported respiratory complications included pneumothorax (14, 12.1%), chylothorax (3, 2.6%), and oxygen requirement (4, 3.4%). Treatments included mTOR inhibitors in 32 (27.6%) and lung transplantation in 1 patient. Conclusion Evaluation for LAM in patients with TSC appears to be underutilized in the U.S. LAM mainly affects women, is linked to TSC2 mutations, and is associated with high rates of renal and dermatologic manifestations. Although guidelines focus on females, LAM can occur in males, highlighting the need for awareness in all TSC patients. Limited lung function and biomarker data reveal gaps in evaluation, with some patients developing severe disease requiring oxygen or lung transplantation. These findings support standardized, genotype-informed surveillance for early detection and targeted care in TSC-related LAM. This abstract is funded by: None

Abstract Rationale Lymphangioleiomyomatosis (LAM) is a rare, progressive, cystic lung disease affecting women. Sirolimus has been shown to stabilize lung function in women with LAM, but real-world data on long-term safety and efficacy are limited. Methods The NIH Multicenter Safety and Durability of Sirolimus for LAM (MIDAS, NCT02432560) observational registry was launched in 2015. All adult (≥18 years) women with LAM (treated or untreated) were eligible to enroll at any of the 20 U.S. sites and followed longitudinally with serial assessments of lung function, health-related quality of life, and treatment related adverse event (TRAEs). Baseline cohort characteristics and TRAEs are summarized using descriptive analyses. Marginal structural models (MSMs) with inverse probability of treatment weighting estimated the causal effect of sirolimus on annualized forced expiratory volume in one-second (FEV1) decline, adjusting for age at LAM diagnosis, prior treatment with sirolimus, menopausal status, race, presence of angiomyolipomas, supplemental oxygen use; time-varying covariates included diffusing capacity for carbon monoxide (DLCO) and serum vascular endothelial growth factor-D (VEGF-D) levels. Results Longitudinal data was available in 350 LAM patients, most of whom (246, 70.3%) had sporadic LAM. The median age at the baseline pulmonary function test (PFT) measurement was 46 years (range: 19 - 74) and the median (IQR) number of serial PFTs obtained per patient was 3 (1 - 5). The average follow-up duration per patient was 2.8 years. Over half of the patients (196, 56%) were treated with sirolimus during the MIDAS observation period for a median (IQR) treatment duration of 4.9 (2.4 - 7.5) years. MSM analysis demonstrated that sirolimus treatment was durably effective and reduced FEV₁ decline by 74.36 mL/year (95% CI: 15.87 - 132.85) compared with no treatment (-85.31 mL/year for the untreated group vs. -10.95 mL/year for the treated group, p = 0.01). Sirolimus was generally well tolerated; treatment interruption ≥3 months was observed in 38 (19.4%) of the 196 sirolimus treated patients. Logistic regression analysis showed that higher levels of FEV1 (odds ratio: OR = 3.12 [1.45 - 7.11], p = 0.005), VEGF-D (OR = 1.0007 [1.0004 - 1.001], p < 0.001), and DLCO (OR = 1.023 [1.0053 - 1.0413, p = 0.01]), were associated with treatment interruption. Conclusions In the MIDAS cohort, sirolimus treatment resulted in durable stabilization of lung function with a favorable safety profile over a 5-year period. These real-world data support sirolimus as a chronic suppressive therapy for LAM, demonstrating durable efficacy in slowing lung disease progression and tolerability with long-term use. This abstract is funded by: National Institutes of Health

Abstract Hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant vasculopathy affecting 1 in 5000 individuals, is the second most common inherited bleeding disorder worldwide. Despite this prevalence, comprehensive data on disease manifestations and complications remain limited. To address this gap, the US Congress allocated funding leading to the Comprehensive HHT Outcomes Registry of the United States (CHORUS), a prospective, 15-center longitudinal registry enrolling unselected patients with confirmed HHT. In this initial report, we describe findings from the first 600 participants, with a median age of 53 (range, 0-88) years and 60% female. Despite most participants developing typical HHT manifestations by age 13 years, the majority (63%) were not diagnosed until mid-to-late adulthood. Recurrent spontaneous epistaxis occurred in 95% of participants, chronic gastrointestinal bleeding in 30%, and heavy menstrual bleeding in 35% of postmenarche females, together resulting in moderate-to-severe mucosal bleeding in 76%. Iron deficiency and/or anemia were diagnosed in 68%, with 41% requiring IV iron and 25% requiring red cell transfusions. Serious complications of solid-organ arteriovenous malformations were frequent, including intracranial hemorrhage (3%), pulmonary hemorrhage (2%), venous thromboembolism (7%), arterial thromboembolism (11%), heart failure (7%), and pulmonary hypertension (7%). These data from CHORUS, the first national US registry of its kind, provide reliable, real-world estimates of the incidence, prevalence, and severity of numerous HHT manifestations and complications. HHT has a high burden of moderate-to-severe bleeding, anemia, thrombosis, and major neurologic and cardiopulmonary complications. There is a mean interval between first symptoms and diagnosis of >2 decades, during which substantial, serious, and preventable HHT morbidity, including early intracranial hemorrhage, may occur. This trial was registered at clinicaltrials.gov as NCT06259292.

Abstract Hereditary hemorrhagic telangiectasia (HHT) results in recurrent severe epistaxis, chronic gastrointestinal bleeding, and other morbid manifestations. Pomalidomide was recently demonstrated to be efficacious for bleeding in HHT in the landmark PATH-HHT trial. Given that the vascular remodeling that results in bleeding improvement may require several months, characteristics associated with treatment response would be invaluable to plan treatment. Using data from PATH-HHT (NCT03910244), we identified characteristics associated with change from baseline in Epistaxis Severity Score (ESS; a well-validated 10-point HHT bleeding scale and the trial’s primary end point) using multivariable-adjusted repeated-measures models. Characteristics associated with a better response to pomalidomide at weeks 16 to 24 of the trial included a higher (more severe) baseline ESS (change from baseline, −0.76 [95% confidence interval (CI), −0.99 to −0.54] points per 1-point higher baseline score, P< .001) and concomitant antifibrinolytic therapy (−0.73 [95% CI, −1.48 to 0.01] vs no therapy, P = .05). Characteristics associated with a less robust response were older age (0.29 [95% CI, 0.05-0.53] per 10 years older, P = .02) and underlying ACVRL1 germ line mutation (0.62 [95% CI, −0.04 to 1.27] vs ENG, SMAD4, or mutation not known, P = .06]. Characteristics notably associated with placebo response (placebo effect) were patient-reported outcome measures, such that those experiencing more severe disease at baseline had less placebo effect. In conclusion, several baseline patient and disease characteristics were associated with pomalidomide response, findings that may help guide patient selection for the use of pomalidomide in HHT. This trial was registered at www.Clinicaltrials.gov as NCT03910244.

Abstract Hereditary hemorrhagic telangiectasia (HHT) causes severe recurrent epistaxis, chronic gastrointestinal bleeding, solid organ arteriovenous malformations, and significant anemia. Although it is the second most common inherited bleeding disorder worldwide, no approved therapies exist. The multicenter, US randomized, controlled PATH-HHT trial demonstrated efficacy of short-term pomalidomide treatment of epistaxis in HHT. However, questions regarding long-term safety, effectiveness, and utility for HHT-associated gastrointestinal bleeding remain. The PATH-HHT ATLAS (after trial longitudinal assessment study) was a multicenter US longitudinal observational study evaluating patients enrolled in PATH-HHT who continued pomalidomide after PATH-HHT through a poststudy drug access program, with ongoing close monitoring per PATH-HHT protocol and as mandated by the US Food and Drug Administration. Sixty-two patients treated with pomalidomide for HHT for up to 4.4 years were included. Significant, durable improvements in mean epistaxis severity score (5.55 points [baseline] to 2.80 points [month 12]; P< .0001) and mean hematologic support score (9.11 red cell unit equivalents [RUEs] during 6 months pretreatment to 5.73 RUEs [months 7-12]; P = .0056) were observed. Pomalidomide was less effective for gastrointestinal bleeding than for epistaxis, particularly in patients with high red blood cell transfusion requirements. Thirty-one patients (50%) underwent dose reduction from 4 mg daily, primarily due to neutropenia, but most maintained effectiveness at 2 or 3 mg daily. Over 105.2 patient-years of pomalidomide treatment, 0 patients developed peripheral neuropathy, 1 developed venous thromboembolism, and 5 developed serious infections. In conclusion, pomalidomide was effective for HHT-associated epistaxis over extended durations, albeit with nontrivial potential toxicities, and may be considered for certain patients with HHT. This trial was registered at www.clinicaltrials.gov as NCT07018401.

Abstract BACKGROUND Hereditary hemorrhagic telangiectasia (HHT) is the second most common inherited bleeding disorder (IBD) worldwide, afflicting 1 in 5,000 people. HHT is likely the most morbid IBD of women. Severe, recurrent epistaxis, gastrointestinal (GI) bleeding, and solid organ arteriovenous malformations (AVMs) cause major clinical and psychosocial morbidity and reduced survival. In recognition of the serious morbidity of HHT as an IBD, in 2022 the U.S. Congress allocated funding to create CHORUS, the Comprehensive HHT Outcomes Registry of the United States (NCT06259292). Herein, we present the initial report from CHORUS. METHODS CHORUS is a prospective, multicenter, U.S. longitudinal registry enrolling unselected patients with HHT, collecting over 2400 data elements. Data were collected by trained research coordinators at enrollment and follow-up visits via the medical record and direct participant interviews. RESULTS Patients. 600 patients with genetically- or Curacao criteria-confirmed HHT were enrolled from November 2023 to April 2025 at 15 U.S. HHT Centers of Excellence. Median (range) age was 53 (0-88) years, and the cohort was 60% female. Despite most patients developing typical HHT disease manifestations by age 13, most HHT diagnoses (63%) were made during mid-to-late adulthood. Mucosal Bleeding. 568 patients (95%) developed recurrent spontaneous epistaxis, with 339 (60%) developing recurrent epistaxis prior to age 13; 43% had at least one nasal surgery/procedure and 22% had at least one medical therapy (e.g., antifibrinolytic or antiangiogenic) for epistaxis. 180 (30%) had a known diagnosis of chronic GI bleeding. Among post-menarche females, 124 (34%) had been diagnosed with heavy menstrual bleeding. 247 (41%) reported other clinically significant mucocutaneous oral or skin bleeding. 454 (76%) had developed moderate-to-severe HHT-associated mucocutaneous bleeding, defined as an Epistaxis Severity Score >4, bleeding requiring targeted pharmaceutical or surgical intervention, IV iron, and/or red cell transfusion. This includes 334 (56%) with moderate-to-severe HHT-associated epistaxis. CNS and Pulmonary Hemorrhage. 16 patients (3%) suffered one or more intracranial hemorrhages (ICH), with 10 (63%) suffering a first ICH by age 25. 13 (2%) suffered one or more pulmonary hemorrhages. Iron Deficiency and Anemia. 408 patients (68%) had been diagnosed with anemia (351, 59%) or iron deficiency (381, 64%). Of those, 247 (61%) and 150 (37%) required IV iron and RBC transfusion, respectively. Solid Organ AVMs. Brain, pulmonary, and liver AVMs were diagnosed in 81 (15%), 268 (45%), and 128 patients (21%), respectively. Just 30 with brain AVMs (37%) had these diagnosed by age 25. 3 patients (2%) had undergone liver transplantation. Thrombosis. Venous and arterial thromboembolism occurred in 44 (7%) and 38 patients (6%), respectively, including 34 (6%) with ischemic stroke (94% of whom had pulmonary AVMs). Other Serious HHT Complications. These included heart failure in 41 patients (7%), pulmonary hypertension in 44 (7%), chronic liver disease in 17 (2.8%), epilepsy in 24 (4%), severe bacterial/deep-seated tissue infection in 35 (6%), and brain abscess in 15 (3%). 205 (34%) developed migraine. Notably, serious CNS manifestations of HHT (brain AVM, ischemic stroke, intracranial hemorrhage, and/or epilepsy) occurred in 128 (21%). 241 (40%) required emergency room visits and/or hospital admissions specifically to manage HHT complications. CONCLUSIONS This first-of-its-kind HHT registry reliably describes for the first time the incidence and severity of numerous HHT complications. Most patients develop moderate-to-severe recurrent epistaxis and/or chronic GI bleeding as well as iron deficiency anemia (usually requiring IV iron and/or RBC transfusion). Heavy menstrual bleeding, thromboembolism, severe cardiopulmonary complications, and serious CNS complications are all substantially more common in HHT than previously thought. Notably, ICH occurred in 3% of patients, which approximates the ICH incidence of hemophilia in the pre-factor prophylaxis era and is ~2-fold and ~9-fold higher than in hemophilia A treated with modern factor prophylaxis (1.6%) and modern non-factor prophylactic agents (0.3%), respectively, per the ATHN registry. This 3% number may be an underestimation given the known high ICH mortality rate, pervasive delay in HHT diagnosis, and the fact that survival post-ICH is necessary to enroll in CHORUS.

Introduction Hereditary hemorrhagic telangiectasia (HHT), the second most common bleeding disorder worldwide, affects 1 in 5000 people and is characterized by extensive formation of telangiectasia and arteriovenous malformations (AVM) in mucosa, lung, brain, and liver. The primary clinical manifestation is recurrent, often severe epistaxis which commonly results in iron deficiency anemia, emergency room visits, hospitalizations, and reduced quality of life (QOL). Though non-randomized and/or underpowered studies have suggested that systemic bevacizumab or thalidomide may be effective in treating HHT, there have been no pivotal studies and therefore no FDA or EMA approved therapies. Methods PATH-HHT was an NHLBI-funded, randomized, placebo-controlled clinical trial conducted at 13 centers in the US to determine the safety and efficacy of pomalidomide for bleeding in HHT. Pomalidomide was supplied by Celgene and Bristol Myers Squibb. Patients were randomized in a 2:1 ratio to receive pomalidomide 4 mg daily or matching placebo for 6 months. Dose reductions were allowed for toxicity. The primary endpoint was the change in the Epistaxis Severity Score (ESS), a well-validated bleeding score in HHT, from baseline (randomization) to the end of the six-month treatment period, analyzed using a mixed model for repeated measures with adjustment for baseline value, center, treatment, visit, and treatment by visit interaction. Key secondary endpoints included 1) change in the average daily self-reported epistaxis duration from the four weeks preceding the baseline visit to weeks 20-24 of treatment, 2) amount of parenteral iron infused or blood transfused, and 3) change in QOL measurements, including an HHT-specific QOL score. Results PATH-HHT opened in November 2019 and was closed to enrollment by the NHLBI in June 2023 after a planned 75% interim analysis met a prespecified threshold for efficacy. A total of 144 patients were randomized and treated (95 pomalidomide, 49 placebo). Early study discontinuation was 25% in pomalidomide: 14% AE, 11% withdrawn, 1 unrelated death, compared with placebo (4% withdrawn). Across groups, 8% were terminated after 12 weeks for early study closure. Participants included 48% females, 11% non-white race; mean (± SD) age was 58.8±12.2 years. The mean ESS at baseline was 5.0±1.5 (4.9 pomalidomide, 5.2 placebo), consistent with moderate to severe epistaxis. At 24 weeks, the ESS in patients treated with pomalidomide decreased by a mean [95% CI] of -1.84 [-2.24, -1.44] and in the placebo group decreased by -0.89 [-1.39, -0.39] (mean difference -0.95 [-1.58, -0.32], p = 0.003) (Figure, Panel A). Difference between groups was apparent by 12 weeks (mean difference -0.52, 95% CI [-1.04, -0.01], p = 0.045). The HHT-specific QOL score, which ranges from 0 to 16 with higher scores indicating more limitations, also decreased more in the pomalidomide (mean -2.6, 95% CI [-3.3, -1.9]) vs the placebo group at 24 weeks (mean -1.2, 95% CI [-2.1, -0.3], p = 0.015) (Figure, Panel B). Adverse events that occurred more in the pomalidomide group included mild to moderate neutropenia (45% vs. 10%), constipation/diarrhea (60% vs. 37%), and rash (36% vs. 10%). Venous thrombosis occurred in 2% of patients in each group. Conclusion PATH-HHT is the largest and the first adequately powered, randomized trial of systemic therapy in HHT. The study demonstrated a significant and highly clinically relevant reduction in epistaxis in pomalidomide-treated patients as well as an improvement in the HHT-specific QOL score. Pomalidomide may offer a novel approach to management of HHT. Since plasma was collected from patients in this study before and at the end of treatment, additional studies may identify biomarkers predicting pomalidomide responses.

Abstract Rationale Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease that predominantly affects women and can worsen with pregnancy, estrogen treatment, and the menstrual cycle, suggesting an important role for estrogen in disease pathogenesis. Objectives To assess the efficacy and safety of the aromatase inhibitor letrozole in the treatment of LAM. Methods Seventeen postmenopausal women with LAM were enrolled in this phase II trial and randomized to receive letrozole 2.5 mg daily (n = 9) or placebo (n = 8) for a period of 12 months. Five patients in each group were also taking sirolimus at baseline and remained on the drug throughout the treatment period. Lung function, exercise capacity, quality of life, and serum vascular endothelial growth factor D (VEGF-D) were measured at baseline and at 3-month intervals. Results Fifteen patients completed the study. Two patients withdrew. There were no differences in adverse events in the letrozole and placebo groups. The target enrollment of 25 patients per arm was not met, so the efficacy of letrozole could not be assessed as planned. After adjusting for sirolimus use, we found that the rate of change in FEV1 for all subjects was −3 ± 3 ml/mo (P = 0.4), and for serum VEGF-D, the rate of change was −0.024 ± 0.009 pg/ml/mo (P = 0.015), showing a steeper decline in the letrozole group (−0.029 ± 0.013; P = 0.025). All patients who were taking sirolimus had a reduction in VEGF-D levels from baseline to the last visit, compared with only half of the patients who were not taking sirolimus. In a post hoc analysis, eight matched letrozole-treated–placebo-treated pairs were constructed, six of which demonstrated better FEV1 improvement for the letrozole-treated patients. Conclusions Letrozole treatment appears to be safe and well tolerated in postmenopausal patients with LAM, including those taking sirolimus. Enrollment in this trial was compromised by the publication of an effective treatment (sirolimus) in the same month as the study opened, resulting in limited power to detect treatment effects. Post hoc matched pairs exploration studies provide tentative support for additional studies of letrozole in LAM. Considering the reduced rate of lung function decline in postmenopausal patients, future studies will likely require enhanced study designs, such as selective enrollment of those with prognostic biomarkers predictive of decline. Clinical trial registered with www.clinicaltrials.gov (NCT01353209).