Benzinga | Sep 21, 2020 07:32AM EDT

BridgeBio Pharma's Calcilytix Therapeutics Initiates Phase 2 Study Of Encaleret For Autosomal Dominant Hypocalcemia Type 1

* Topline proof-of-concept results in ADH1 anticipated in 2021

* Currently, there are no approved therapies for ADH1

PALO ALTO, Calif., Sept. 21, 2020 (GLOBE NEWSWIRE) -- BridgeBio Pharma, Inc. (NASDAQ:BBIO) affiliate Calcilytix Therapeutics, Inc. announced today the initiation of a Phase 2 single-center study of encaleret (CLTX-305) in individuals with ADH1 conducted at the National Institutes of Health. ADH1 is a rare, inherited disease caused by gain-of-function mutations in the calcium sensing receptor (CaSR) resulting in abnormally low serum calcium and high urine calcium and a range of debilitating symptoms. Encaleret sulfate is an investigational oral therapy being studied to address ADH1 at its source by antagonizing the CaSR.

"Patients with ADH1 are currently treated with calcium supplements with a goal of raising their serum calcium levels toward the normal range. Unfortunately, conventional therapy can exacerbate patients' high urine calcium levels and lead to kidney stones and long-term kidney injury," said Michael Collins, M.D., Senior Investigator, Skeletal Disorders and Mineral Homeostasis Section of the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health. "We are working with BridgeBio and Calcilytix to investigate whether encaleret, a therapy that targets the root cause of this disease, could potentially be considered as a future treatment option for our patients."

The Phase 2 trial will enroll up to 16 individuals with ADH1 in an open-label, dose-ranging study to evaluate the safety, tolerability, pharmacodynamics, pharmacokinetics, and efficacy of single and multiple doses of encaleret. This study will include two treatment cohorts evaluated over three study periods, including inpatient observation at the NIH. If doses of encaleret are observed to be well-tolerated and demonstrate the potential to normalize blood and urine calcium levels, participants may be treated for up to 26 weeks.

"Encaleret has been previously shown to be well-tolerated and increase serum calcium levels in healthy volunteers and individuals with osteoporosis, a profile that encouraged our investigation of the compound in ADH1 patients," said Jonathan C. Fox, M.D., Ph.D., Calcilytix's Chief Medical Officer. "If successful, this initial study will provide clear proof of concept that antagonizing the CaSR can address the underlying cause of ADH1. Our goal is to develop an approved treatment to substantially reduce the current unmet medical need for these patients."

The company expects to report topline proof-of-concept results from this Phase 2 study in 2021. This program will be featured at BridgeBio's upcoming R&D Day on September 29 from 8:30 am ET - noon. The event will be webcast, with a link available on the event calendar at https://investor.bridgebio.com/.