Zelos Therapeutics

About Zelos Therapeutics

Zelos Therapeutics was a clinical-stage biopharmaceutical company focused on developing treatments for bone disorders like osteoporosis. Established in 2001, the company aimed to address large, underserved markets by advancing product opportunities with significant commercial potential through late-stage clinical trials. The company's core strategy revolved around stimulating bone formation using parathyroid hormone (PTH) analogs.

The lead product candidate was ZT-031 (formerly Ostabolin-C), a proprietary cyclic 31-amino acid PTH analog developed for treating severe osteoporosis. This treatment was designed as a bone formation agent. Clinical studies, including a 12-month Phase 2 trial with 261 postmenopausal women, showed that ZT-031 led to significant increases in bone mineral density with a rapid onset and no observed adverse events of hypercalcemia. The company also explored an intranasal spray formulation of ZT-031 to improve patient compliance and expand its market potential. In July 2008, Zelos reached an agreement with both the U.S. FDA and the European Medicines Agency (EMEA) for a Phase 3 registration study of ZT-031. The company was later known as Azelon Pharmaceuticals.