The features of rare pathogenic BMPR2 variants in pulmonary arterial hypertension: Comparison between patients and reference population

Association between Genotype, Presentation, and Outcome in Childhood Idiopathic and Hereditary Pulmonary Arterial Hypertension

BACKGROUND

Paediatric-onset idiopathic/hereditary pulmonary arterial hypertension (IPAH/HPAH) is partially linked to genetic factors that may also affect treatment response and outcome. The relation between clinical characteristics and pathogenicity of gene variants in childhood IPAH/HPAH is still not well understood.

METHODS

We retrospectively analyzed IPAH/HPAH paediatric patients aged between 3 months and 18 years under follow-up at a large tertiary referral center. Whole-exome sequencing focused on PAH high-risk genes was performed in all patients. Pathogenicity grading of gene variant sites was assessed using ClinVar and population frequencies. The association between gene variants and death was studied using Cox proportional multivariate models.

RESULTS

Overall, 129 patients (54.3% females; 91.5% on PAH therapy) with a median age at diagnosis of 6.8 (IQR 3.4-10.7) years were included. A relevant PAH gene variant was detected in 95 patients (73.6%). The most common variants were in the BMPR2 (n = 43, 3%) gene. Over a median follow-up period of 27.6 months, 26 children died. The presence of a likely pathogenic genetic variant was significantly associated with survival (HR: 3.56, p = 0.005) on multivariable Cox analysis. The number of PAH-specific drugs at presentation was associated with better survival in the cohort with pathogenic variants (p = 0.02).

CONCLUSIONS

Pathogenic/likely pathogenic genetic variants are prevalent in children with PAH and are related to a worse prognosis irrespective of other recognized risk factors in this population. Combination PAH therapy was associated with superior prognosis in children with pathogenic variants or BMPR2 variants. Therefore, proactive medical therapy should be employed in this population.

"NOVEL MECHANISMS TARGETED BY DRUG TRIALS IN PULMONARY ARTERIAL HYPERTENSION"

Pulmonary arterial hypertension (PAH) is a rare disease associated with abnormally elevated pulmonary pressures and right heart failure resulting in high morbidity and mortality. While PAH prognosis has improved with the introduction of pulmonary vasodilators, disease progression remains a major problem. Given that available therapies are inadequate for preventing small vessel loss and obstruction, there is an active interest in identifying drugs capable of targeting angiogenesis and mechanisms involved in regulation of cell growth and fibrosis. Among the mechanisms linked to PAH pathogenesis, recent preclinical studies have identified promising compounds that are currently being tested in clinical trials. These drugs target seven of the major mechanisms associated with PAH pathogenesis: BMP signaling, tyrosine kinase receptors, estrogen metabolism, extracellular matrix, angiogenesis, epigenetics, and serotonin metabolism. In this review, we will discuss the preclinical studies that led to prioritization of these mechanisms and will discuss recently completed and ongoing phase 2/3 trials using novel interventions such as sotatercept, anastrozole, rodatristat ethyl, tyrosine kinase inhibitors, and endothelial progenitor cells among others. We anticipate that the next generation of compounds will build upon the success of the current standard of care and improve clinical outcomes and quality of life of patients afflicted with PAH.