• EXT608 was safe and well-tolerated and showed an effective increase in serum calcium
  • The initial pharmacokinetic profile is consistent with a once-weekly dosing regimen
  • Plans are underway to move directly into a Phase 2a trial

NEWTON, MA, USA I May 11, 2023 I Extend Biosciences (“ExtendBio”), a clinical stage biopharmaceutical company utilizing a proprietary platform technology to develop advanced therapeutic peptides, today announced positive results from its first-in-human trial of EXT608. An interim data analysis shows that EXT608 was safe and well tolerated, with no serious adverse events reported. It also shows a dose dependent increase in serum calcium, without a concomitant increase in urinary calcium. A prolonged suppression of endogenous parathyroid hormone (PTH) was also observed, as anticipated. An early pharmacokinetic analysis suggests that EXT608 can be effective when dosed once-weekly. The data provide a strong rationale to proceed to the next stage of clinical development and also offer valuable guidance for selecting a starting dose in the Phase 2 trial.

“These data represent an important validation of our platform technology and serve as a major milestone as we strive to provide a viable solution for patients living with hypoparathyroidism,” said Tarik Soliman Ph.D., ExtendBio’s Co-Founder and Chief Executive Officer. “The data not only demonstrate that EXT608 is safe and well-tolerated, but they also show the potential for the compound to replace PTH for an extended period of time, which would result in increased patient adherence and an improved quality of life. EXT608 has the potential to be a promising solution for physicians and patients seeking a convenient treatment option to effectively manage this debilitating disease. We look forward to rapidly advancing EXT608 into the next phase of clinical study.”

Hypoparathyroidism is a chronic, rare endocrine disorder characterized by low levels of parathyroid hormone in the bloodstream. It is estimated to impact more than 200,000 people globally. PTH, which is produced by the parathyroid glands located in the neck, helps to regulate serum calcium levels in the body. Without the renal calcium-retaining effects of PTH, hypoparathyroidism can lead to a range of serious physical health complications, such as seizures, heart arrhythmias, and kidney damage, and can also cause anxiety, depression, and other mental health problems due to the effect of low calcium levels on the brain. There is no cure for hypoparathyroidism, and the current standard of care (calcium and vitamin D supplementation) often still leads to hypocalcemia and hypercalciuria.

EXT608, ExtendBio’s lead program, is a long-acting, parathyroid hormone-based therapy designed to replace the physiological effects of PTH with significantly less frequent dosing and improved bioavailability. The ongoing Phase 1 trial is a double-blind, randomized, placebo-controlled trial involving 24 healthy participants across 6 cohorts who receive a single ascending subcutaneous dose of EXT608. The study is nearing completion and a full data analysis is underway, with plans to present the results at an upcoming medical meeting.

About EXT608

EXT608 is a long-acting derivative of parathyroid hormone (PTH). Developed using ExtendBio’s D-VITylation® platform, the compound is fully active at the PTH receptor upon injection, and the company plans to make it available for patients in a simple, easy to use single-use disposable syringe. ExtendBio received Orphan Drug Designation for EXT608 from FDA in 2022. The preclinical and clinical development program for EXT608 has been supported in part by MassVentures and by SBIR grants from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

About Extend Biosciences Inc.

Extend Biosciences Inc. is a clinical-stage biopharmaceutical company that utilizes its platform technology to develop next generation therapeutic peptides with superior pharmacokinetic properties. The proprietary technology, D-VITylation®, harnesses the biology of vitamin D and the reversible binding properties of the serum-circulating vitamin D binding protein. By utilizing this natural pathway, D-VITylation® prevents a vitamin D-conjugated therapeutic from renal clearance, thereby significantly extending its half-life without compromising bioactivity. ExtendBio has multiple D-VITylated assets in their portfolio, including EXT418, a long-acting ghrelin being evaluated as a potential treatment for cancer cachexia. For more information, please visit www.extendbio.com.

This study is registered in ClinicalTrials.gov (NCT05408663).

SOURCE: Extend Biosciences