May 31 (Reuters) - Sanofi and partner

Regeneron Pharmaceuticals ( REGN ) have secured the European

regulator's backing for use of Dupixent in patients with a

chronic lung disease even as the U.S. Food and Drug

Administration (FDA) extended its review.

French drugmaker Sanofi and its U.S. partner have been

counting on expanding the use of the drug as an add-on

maintenance treatment for chronic obstructive pulmonary disease

(COPD) - also called 'smoker's lungs' as the lifelong condition

commonly affects cigarette smokers.

The disease, which causes restricted airflow and breathing

problems, affects nearly 16 million U.S. adults and over 35

million people in Europe, according to government data.

French drugmaker Sanofi said in April it expects the target

patient population eligible for the drug to be roughly 300,000

patients in the U.S. alone. It anticipated steeper growth in

Dupixent sales in 2025 after its launch for COPD in the country.

But the FDA pushed back its deadline for the review by three

months to Sept. 27 as it sought additional data from the

drugmakers on the efficacy of Dupixent as an add-on COPD

treatment, the drugmakers said on Friday.

The drugmakers said they were still "confident" the U.S.

approval would come "as quickly as possible".

On the other hand, the European Medicines Agency's advisory

panel recommended approval of Dupixent in Europe for patients

with COPD for whom systemic corticosteroids or surgery did not

provide adequate disease control, the agency said on Friday.

In Europe, the final decision rests with the European

Commission, which usually follows the guidance from the EMA's

Committee for Medicinal Products for Human Use.

The drug is already approved in many countries for various

immune system-related conditions like asthma and eczema. In

2023, Dupixent generated 10.72 billion euros ($11.63 billion) in

revenue, according to Sanofi's data.

($1 = 0.9215 euros)

(Reporting by Leroy Leo in Bengaluru and Diana Mandiá, editing

by Tassilo Hummel and Devika Syamnath)