Spruce Bio Raises $88M for Clinical Tests of Rare Endocrine Disease Drug

Xconomy San Francisco — 

Spruce Biosciences has raised $88 million to advance clinical testing of a drug for a rare inherited endocrine disorder that can lead to a potentially life-threatening hormonal imbalance.

San Francisco-based Spruce aims to treat a form of congenital adrenal hyperplasia (CAH), an inherited condition that leads to a deficiency in enzymes needed to produce certain hormones, which in turn leads to the overproduction of other hormones. The disease stems from a mutation in the gene that encodes 21-hydroxylase, an enzyme key to the production of adrenal hormones. Spruce aims to treat classical CAH, the more common and more severe form of the disease.

Lacking 21-hydroxylase leaves patients unable to make cortisol, a stress hormone produced to respond to stress, illness, and injury. CAH also leads the body to overproduce the male sex hormone androgen. Current treatments include steroids to replace the low hormones. But this treatment can lead to side effects. Spruce’s drug, tildacerfont, is intended to normalize elevated androgen levels. The company says its drug could allow physicians to reduce chronic use of steroids by CAH patients.

Spruce’s new capital follows positive clinical trial results released last September. In a Phase 2a study, the company reported that the levels of adrenocortcotropic hormone, the target of tildacerfont, were reduced by an average of 74 percent from baseline. The company also reported reductions in downstream hormonal targets that are indicators of CAH. Furthermore, 60 percent of patients with elevated adrenocortcotropic hormone saw levels return to normal by week 12 of the 12-week study. No serious adverse events were reported from the clinical trial, and the problems that did occur were classified as mild and not related to the Spruce drug.

There are other companies in the hunt for a new CAH drug. Ann Arbor, MI-based Millendo Therapeutics (NASDAQ: MLND) has advanced its drug, nevanimibe, to Phase 2b testing. That drug takes a different approach by blocking an enzyme that leads to the overproduction of androgen. Neurocrine Biosciences (NASDAQ: NBIX) of San Diego also aims to reduce androgen production. Its drug blocks a protein in the pituitary gland, which in turn reduces production of a hormone key to androgen production. The Neurocrine drug, crinecerfont, is in Phase 2 testing in both adults and children.

Spruce says it will use the new cash to evaluate the ability of its drug to reduce glucocorticoid steroid use in a late-stage clinical trial enrolling adult CAH patients. The company also plans to complete a mid-stage study testing the drug in children.

The latest investment was co-led by Omega Funds and Abingworth. Earlier investors Novo Holdings and RiverVest Venture Partners also participated, joined by new investors HealthCap Partners, Rock Springs Capital, Surveyor Capital, Aisling Capital, and Sands Capital.

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