FDA Approves First TK2d Therapy Following Columbia-Led Study

The FDA has approved KYGEVVI®, the first therapy for Thymidine Kinase 2 deficiency (TK2d), advancing decades of work led by Michio Hirano, MD, Lucy G. Moses Professor of Neurology; Chief, Division of Neuromuscular Medicine; Director of the MDA Clinic and the H. Houston Merritt Neuromuscular Research Center at Columbia University Irving Medical Center. The approval follows recently published study results detailing long-term clinical outcomes of deoxynucleoside therapy in TK2d.

The Irving Institute’s Clinical Research Resource (CRR) supported this translational pathway by approving and providing clinical research infrastructure for two TK2d studies led by Dr. Hirano: a compassionate-use protocol and a Phase 2 open-label clinical study, which enrolled participants between 2019 and June 2025 and generated key safety and efficacy data informing the regulatory submission.

The Muscular Dystrophy Association has also released a short video highlighting the research journey, including Dr. Hirano’s reflections on the path from compassionate use to FDA approval.

KYGEVVI® now represents the first approved treatment for TK2d and a major milestone for rare-disease research at Columbia.

Read the full study here.