Molecular imaging of the human pulmonary vascular endothelium in pulmonary hypertension: a phase II safety and proof of principle trial

• Published in: European journal of nuclear medicine and molecular imaging Vol. 44; no. 7; pp. 1136 - 1144
• Main Authors: Harel, François, Langleben, David, Provencher, Steve, Fournier, Alain, Finnerty, Vincent, Nguyen, Quang T., Letourneau, Myriam, Levac, Xavier, Abikhzer, Gad, Guimond, Jean, Mansour, Asmaa, Guertin, Marie-Claude, Dupuis, Jocelyn
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2017; Springer Nature B.V; Springer Verlag (Germany) [1976-....]
• Subjects: Adrenomedullin; Adult; Albumin; Cardiology; Case-Control Studies; Embolism; Embolisms; Endothelium; Endothelium, Vascular - diagnostic imaging; Female; Health risk assessment; Humans; Hypertension, Pulmonary - diagnostic imaging; Hypertension, Pulmonary - pathology; Image Processing, Computer-Assisted; Imaging; Injection; Life Sciences; Lung - blood supply; Lung diseases; Male; Medicine; Medicine & Public Health; Middle Aged; Molecular Imaging - adverse effects; Nuclear Medicine; Oncology; Original; Original Article; Orthopedics; Perfusion; Pulmonary embolisms; Pulmonary hypertension; Radiology; Reproducibility of Results; Safety; Single photon emission computed tomography; Thromboembolism; Molecular imaging; Pulmonary embolism; Adrenomedullin; Nuclear medicine; Peptide; Pulmonary hypertension
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-017-3655-y

Purpose The adrenomedullin receptor is densely expressed in the pulmonary vascular endothelium. PulmoBind, an adrenomedullin receptor ligand, was developed for molecular diagnosis of pulmonary vascular disease. We evaluated the safety of PulmoBind SPECT imaging and its capacity to detect pulmonary vascular disease associated with pulmonary hypertension (PH) in a human phase II study. Methods Thirty patients with pulmonary arterial hypertension (PAH, n  = 23) or chronic thromboembolic PH (CTEPH, n  = 7) in WHO functional class II ( n  = 26) or III ( n  = 4) were compared to 15 healthy controls. Lung SPECT was performed after injection of 15 mCi 99m Tc-PulmoBind in supine position. Qualitative and semi-quantitative analyses of lung uptake were performed. Reproducibility of repeated testing was evaluated in controls after 1 month. Results PulmoBind injection was well tolerated without any serious adverse event. Imaging was markedly abnormal in PH with ∼50% of subjects showing moderate to severe heterogeneity of moderate to severe extent. The abnormalities were unevenly distributed between the right and left lungs as well as within each lung. Segmental defects compatible with pulmonary embolism were present in 7/7 subjects with CTEPH and in 2/23 subjects with PAH. There were no segmental defects in controls. The PulmoBind activity distribution index, a parameter indicative of heterogeneity, was elevated in PH (65% ± 28%) vs. controls (41% ± 13%, p  = 0.0003). In the only subject with vasodilator-responsive idiopathic PAH, PulmoBind lung SPECT was completely normal. Repeated testing 1 month later in healthy controls was well tolerated and showed no significant variability of PulmoBind distribution. Conclusions In this phase II study, molecular SPECT imaging of the pulmonary vascular endothelium using 99m Tc-PulmoBind was safe. PulmoBind showed potential to detect both pulmonary embolism and abnormalities indicative of pulmonary vascular disease in PAH. Phase III studies with this novel tracer and direct comparisons to lung perfusion agents such as labeled macro-aggregates of albumin are needed. Clinical trial ClinicalTrials.gov, NCT02216279