** Shares of drug developer OS Therapies OSTX.A rise 31.1% to $2.61 in morning trade

** Co says it is starting commercial production of its experimental therapy, OST-HER2 to treat a type of bone cancer called osteosarcoma

** OSTX says OST-HER2 has received "rare pediatric disease", "fast-track" and "orphan drug" designations from the U.S. FDA

** Co says it anticipates submitting an application for potential approval to the FDA for OST-HER2 in osteosarcoma in 2025

** OSTX adds if the therapy is approved, it would be eligible to receive a priority review voucher that it could then sell

** Stock fell 20.7% since its debut

(Reporting by Padmanabhan Ananthan)

((Padmanabhan.Ananthan@thomsonreuters.com;))