FDA Greenlights Kygevvi as Pioneering Therapy for Thymidine Kinase 2 Deficiency in Adults and Kids | iPharmaCenter

The U.S. Food and Drug Administration has endorsed Kygevvi (doxecitine and doxribtimine) oral powder, marking the inaugural authorized remedy for thymidine kinase 2 deficiency (TK2d) among grown-ups and young patients showing signs by age 12 or earlier.

Developed by UCB, the drug targets a devastating mitochondrial disorder previously limited to symptom management alone.

Grasping TK2d Challenges

TK2d represents a scarce inherited condition disrupting mitochondrial DNA production, sparking relentless muscle decline and breathing issues that often prove lethal in early childhood.

Affecting roughly 1-2 per million globally, it leaves families without targeted interventions until now, with symptom starters before age 12 facing dire three-year survival odds.

Approval Backing and Survival Gains

Regulatory nod stems from a Phase 2 trial, chart audits, and access initiatives covering 82 individuals, pitting treated cases against symptom-age-matched controls. Findings reveal an 86% drop in death likelihood post-therapy onset, with median treatment spanning four years at doses around 762 mg/kg daily. Median symptom start sat at 1.5 years among analyzed participants.

Treatment Mechanics and Side Effects

This nucleoside duo supplies vital DNA components to bypass faulty TK2 enzymes, rebuilding muscle mitochondrial reserves as proven in lab models.

Common issues hit 5% or more, featuring loose stools, gut discomfort, nausea, and rises in liver markers ALT/AST, warranting standard oversight.

UCB snagged Orphan, Breakthrough, Priority, and Rare Pediatric tags, plus a Priority Review Voucher post-approval.

EMA scrutiny is ongoing, with U.S. launch eyed for Q1 2026 alongside patient aid initiatives.