June 11 (Reuters) - Novartis NOVN.S said on Thursday an experimental drug, which it acquired as part of its $12 billion takeover of Avidity, showed promise in an early-to-mid-stage study in patients with a type of genetic muscle disorder characterized by slowly progressive muscle weakness.

• The Swiss drugmaker said the drug, known as del-brax, lowered two blood markers linked to the disease and showed reduced signs of muscle damage in patients with facioscapulohumeral muscular dystrophy.

• Novartis said the drug shows potential to become the first disease-modifying treatment for FSHD, which can cause weakness in the face, shoulders, arms and other muscles.

• The company estimates it affects about 45,000 to 87,000 people in the U.S. and EU.

• The drug's safety profile was consistent with previous results, the company said.

• Novartis plans to discuss the data with health regulators around the world, while a late-stage study of the drug is currently enrolling patients.