Potential PAH Therapy Identified by Cellular Screen of Thousands

By screening thousands of potential candidates, researchers have identified a compound, called AG1296, that may be useful for the treatment of pulmonary arterial hypertension (PAH).

Their findings were published in the journal Science Translational Medicine, in a study, “iPSC–endothelial cell phenotypic drug screening and in silico analyses identify tyrphostin-AG1296 for pulmonary arterial hypertension.”

In PAH, the small blood vessels that transport blood in the lungs — the pulmonary arteries — become narrow, resulting in increased blood pressure and making the heart work harder to pump blood through the body.

One of the characteristic features of PAH is dysfunction of endothelial cells — the cells that line the inside of blood vessels. In the new study, researchers at Stanford University and Cincinnati Children’s Hospital used high-throughput screening combined with in silico (computer) analyses of existing RNA datasets to identify compounds that might reverse PAH.

To do this, they used induced pluripotent stem cell (iPSCs). Stem cells are a type of cell that is able to grow and differentiate into other cell types; iPSCs are a type of lab-generated stem cell that is reverse-engineered from adult cells. In the study, the researchers generated iPSCs from six PAH patients, and used these iPSCs to generate endothelial cells for further experimentation.

“This is the first time for using iPSCs to screen for compounds for PAH, but people have been using similar strategies to screen for new therapies for other conditions,” Mingxia Gu, MD, PhD, assistant professor at Cincinnati Children’s and lead author of the study, said in a press release.

“Using patient-specific iPSCs for developing precision medicine is a new and promising field,” she added.

Using the stem-cell derived endothelial cells, the researchers screened a large library of compounds to look for ones that might improve the cells’ survival under stressful conditions.

“In this study, we screened a library of 4500 compounds at different stages of clinical development in eight different doses,” said Gu. “Of the six compounds that improved cell survival, we identified the tyrosine kinase inhibitor AG1296 as the lead compound for further investigation.”

Tyrosine kinase inhibitors, or TKIs, are a class of medications that work by blocking the activity of certain proteins — the eponymous tyrosine kinases. These proteins help to coordinate various cellular processes by adding phosphate groups to other proteins. Different TKIs can have varying effects on the body, depending on which specific tyrosine kinases they most affect.

Additional biological tests supported AG1296 as a potential PAH therapy: treatment with the compound normalized various molecular signaling signatures in cells, and experiments in rat models suggested that treatment reduces lung damage and strain on the heart. AG1296 outperformed other TKIs in several measures.

“Drug discovery for PAH can be accelerated by combining phenotypic screening [assessing changes in cells or an animal] with in silico analyses of publicly available datasets,” the scientists wrote.

They are hoping to bring AG1296 eventually into clinical trials to test it in PAH patients, but this will require at least a year’s worth of preparation and safety testing beforehand, according to Gu.