Biotech investors from six nations have committed $118 million to Mineralys Therapeutics Inc., a 15-person, Radnor-based company developing a high-blood-pressure drug using a different approach it hopes will help African Americans and others who have lower response rates to current therapies.

Drugs developed in the 1980s and 1990s — ACE inhibitors , beta-blockers, and calcium-channel blockers — help tens of millions of Americans stabilize their blood pressure, preventing strokes and heart attacks.

But an estimated “half” of the more than 60 million Americans now in treatment cannot reduce their pressure to safe levels, and 30 million more aren’t being treated at all, said Jon Congleton, Mineralys’ chief executive, in an interview, citing industry data.

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While ACE inhibitors and channel blockers effectively “loosen the pipes” — patients’ arteries — allowing blood to flow more freely and reducing pressure, Congleton said, Mineralys’ product seeks to lower high-pressure blood flow itself by slowing production of the hormone aldosterone, which picks up sodium in the body, boosting blood flow and pressure.

Congleton is a former head of Israel-based Teva Pharmaceuticals’ Philadelphia-based neuroscience business and its Global Medicines Group. At a previous job, he sold the earlier generation of blood-pressure medications, then served as CEO of two start-ups.

Mineralys is developing the MLS-101 drug under license from Japan’s Mitsubishi Tanabe Pharma Corp. Mineralys, which has its offices in the Radnor Financial Center, was founded by Japan-based doctor and biotech investor BT Slingsby. The firm’s medical director, David Rodman, is a Penn-trained physician who previously worked at Novartis, Vertex, and other biotech firms.

According to Congleton, the familiar hypertension drugs work well enough that doctors have become comfortable simply prescribing more of them, in different combinations, to slow-responding patients.

“We’d like to break that paradigm” and give doctors alternate treatments that will reduce pressure more effectively for those who haven’t shown progress, he said.

Overweight patients are particularly unresponsive, and “African American hypertensity is very difficult to control,” Congleton said. “There’s an opportunity that MLS-101 could help.”

“We’ve known for many years that there’s definitely a different pattern of response” to hypertension drugs, among African Americans as a group, and “it requires different medications, in somewhat different doses,” concurred Matthew Weir, professor of medicine and chief of nephrology (kidney study and treatment) at the University of Maryland School of Medicine, and an adviser to Mineralys.

He expects the difference is more likely due to “socio-cultural factors” such as diet, rather than genetics, “although we don’t know with certainty.” The more effective drugs that are on the market, the easier it is for doctors to “mix and match” prescriptions for patients effectively, Weir added.

The aldosterone inhibitor that Congleton’s company is developing “causes sodium retention and potassium excretion,” which works better with people more sensitive to salt as a factor in high blood pressure, and “it may be instrumental in facilitating better blood pressure control in people of African heritage who have this blood pressure phenotype,” Weir said.

Congleton expects it will take up to five years to get the drug through clinical testing approvals. Having already passed a round of safety tests, Mineralys is planning “dialogues with the FDA” to set up clinical tests, and will add up to 10 people onto its staff over the next year and a half as it ramps up development.

The new round of investors is led by RA Capital Management of Boston and Paris-based Andera Partners.

Other new investors include RTW Investments of New York, Rock Springs Capital of Baltimore, SR One Capital Management of San Francisco (with a satellite office in Wayne), Sectoral Asset Management of Montreal, Spain-based Ysios Capital, HealthCor Management of New York, and Boulder Ventures of Colorado.

Repeat investors from last year’s initial $40 million fund-raising round include Mineralys founder Slingsby’s firm, Catalys Pacific, based in Tokyo; Samsara BioCapital of Silicon Valley, and HBM Healthcare of Switzerland.

The new lead investors have each named partners to Mineralys’ board: Olivier Litzka, for Andera, and Derek DiRocco, of RA.