California-based biotechnology company Septerna has raised another $150 million to fund its work researching small molecule drugs that target a ubiquitous group of proteins known as GPCRs.
The Series B financing, announced Tuesday and led by RA Capital Management, will help Septerna advance its lead program into clinical testing, as well as further develop other preclinical assets.
GPCRs, or G protein-coupled receptors, handle a wide array of signals across cellular membranes, making them a prime target for drug developers. According to an estimate, as many one-third of drugs approved by the Food and Drug Administration target GPCRs in some fashion.
Despite their prevalence, GPCRs aren’t made in large quantities by cells and can be difficult to isolate. Septerna claims its approach can overcome these hurdles and, last year, raised an initial $100 million to jumpstart its research.
“Drugs developed to target GPCRs have transformed the treatment of several diseases; however, the majority of today’s treatments target just a few GPCR subfamilies,” said Jake Simson, partner at RA Capital, in Tuesday’s statement. “Septerna’s ability to isolate fully functional native GPCR proteins and rapidly identify candidate-like molecules has the potential to unlock a wide range of previously intractable GPCR targets across multiple therapeutic areas.”
Septerna’s lead program targets a GPCR known as the parathyroid hormone 1 receptor, and will be developed as a treatment for hypoparathyroidism, a condition that in severe cases can result in seizures, heart arrhythmia and kidney failure.
Joining RA Capital in the Series B were, among others, existing investors Third Rock Ventures, Samsara BioCapital, Casdin Capital as well as a handful of new investors. RA Capital’s Simson will join Septerna’s board of directors.