– Increase in endogenous cortisol production achieved in all patients in higher dose cohorts of BBP-631, a result seen for the first time ever in CAH patients

– The gene therapy was well tolerated with no treatment-related serious adverse events (SAEs) reported

– Despite novel scientific advancements achieved with this program, the data do not warrant additional capital investment at this time and the gene therapy budget is being significantly reduced

PALO ALTO, CA, USA I September 10, 2024 I BridgeBio Pharma, Inc. (Nasdaq: BBIO) (“BridgeBio” or the “Company”), a commercial-stage biopharmaceutical company focused on genetic diseases, today announced topline results from the Phase 1/2 open-label ADventure study investigating BBP-631, the Company’s investigational adeno-associated virus (AAV) 5 gene therapy, for the treatment of congenital adrenal hyperplasia (CAH).

The Phase 1/2 open-label ADventure study was designed to evaluate the safety, tolerability and pharmacodynamic activity of BBP-631 in adults with classic CAH. To date, key results from the study include:

  • Increased endogenous cortisol production was achieved in all patients at higher doses. A maximum change from baseline post-ACTH stimulation test of 4.7 μg/dL and 6.6 μg/dL was observed at the two highest dose levels, respectively, with cortisol levels as high as 11 μg/dL achieved.
  • Substantial and durable increases in 11-deoxycortisol, the product of 21-hydroxylase, and reductions in 17-hydroxyprogesterone (17-OHP), the substrate of 21-hydroxylase, provide compelling evidence of durable BBP-631 transgene activity.
    • At the highest dose levels, sustained 11-deoxycortisol averaged a 55-fold increase from baseline with a maximum of 99-fold increase from baseline. These represent an average maximum of 23-fold the upper-limit of normal.
    • Robust reduction in 17-hydroxyprogesterone, with the majority of patients reaching a reduction of ≥50%, with a max reduction of 95%.
  • BBP-631 has been well tolerated with only mild to moderate treatment-emergent adverse events (TEAEs) and no treatment-related SAEs reported.

“While the data to date are not yet transformational, the study showed for the first time that people living with CAH can indeed make their own cortisol, and that gene therapy can be safely administered in this patient population. We remain committed to finding the right partner for those in the CAH community and are grateful to the participants and those who expressed interest in both the pre-screening study and the ADventure study. We also want to thank the ADventure study investigators and staff, the CAH patient advocacy organizations and the broader CAH community,” said Neil Kumar, Ph.D., CEO and Founder of BridgeBio.

“Given that the results of the trial did not meet the threshold to warrant additional capital investment at this time, BridgeBio will be reducing the gene therapy budget more than $50M, consistent with our capital allocation principles, and reserving gene therapy for priority targets that we cannot treat any other way,” said Brian Stephenson, Ph.D., CFA, Chief Financial Officer of BridgeBio. “We believe that gene therapies have the potential to fulfill a significant unmet need and are eager to work closely with the FDA and the Canavan community with the goal of bringing our therapy to families living with Canavan disease as fast as possible.”

BridgeBio will no longer be pursuing development of BBP-631 for CAH and the Company is actively seeking partnership opportunities to support future development of BBP-631 or next-generation gene therapies for the treatment of CAH, a very prevalent genetic disease that still has significant unmet need, with more than 75,000 cases estimated in the United States and European Union.

About BBP-631
BBP-631 is an AAV5 gene therapy developed to treat CAH due to 21-hydroxylase deficiency at its source. BBP-631 is designed to deliver a functional copy of the 21-hydroxylase gene and has been shown through multiple preclinical studies to result in efficient and persistent delivery to the adrenal gland, where hormones are naturally made. If successful, BBP-631 may restore the body’s hormone and steroid balance by enabling people with CAH to naturally make their own cortisol and aldosterone. It could also allow for people with CAH to eliminate or significantly reduce their daily glucocorticoid or mineralocorticoid doses, which is the current standard of care for patients.

About Congenital Adrenal Hyperplasia (CAH)
Affecting approximately 75,000 people in the United States and European Union, CAH is a group of genetic disorders that affect the adrenal glands, which is caused by a mutation in the gene encoding for 21-hydroxylase, an enzyme essential for making the hormones cortisol and aldosterone which are critical for various physiologic functions. Cortisol is necessary for the body to respond to injury, stress or illness, and aldosterone is required to maintain proper blood pressure and sodium levels. Unable to produce cortisol and aldosterone, people with classic CAH cannot mount the healthy physiological response to stressors, such as illnesses, that allows their heart, lungs, kidneys and other organs to compensate for the stress, which can be life-threatening. These adrenal crises can be particularly dangerous for young children.

About BridgeBio Pharma, Inc.
BridgeBio Pharma, Inc. (BridgeBio) is a commercial-stage biopharmaceutical company founded to discover, create, test and deliver transformative medicines to treat patients who suffer from genetic diseases. BridgeBio’s pipeline of development programs ranges from early science to advanced clinical trials. BridgeBio was founded in 2015 and its team of experienced drug discoverers, developers and innovators are committed to applying advances in genetic medicine to help patients as quickly as possible. For more information visit bridgebio.com and follow us on LinkedInTwitter and Facebook.

SOURCE: BridgeBio Pharma