Nov 27 (Reuters) – Sanofi (SASY.PA) plans to seek U.S. approval for its best-selling anti-inflammatory drug Dupixent to be used in the treatment of “smoker’s lung”, also known as COPD, after a second large trial showed significant benefits.

Sanofi, which is collaborating on the drug with Regeneron (REGN.O), said in a statement on Monday that a second Dupixent phase 3 trial for chronic obstructive pulmonary disease showed the drug reduced exacerbations of the disease by 34%.

The findings were from an interim analysis after positive results from a first trial known as BOREAS. Given “overwhelming” efficacy, they will be considered to serve as the primary analysis of the trial, the company said, adding details would be presented at an as yet undisclosed medical conference.

Sanofi and Regeneron, which have been testing the drug on current and former smokers who can’t control their COPD with established inhalers, had embarked on the second trial to bolster the statistical reliability of the read-outs.

COPD, which damages the lungs progressively, is the third leading cause of death worldwide. It can also be caused by air pollution and related occupational hazards.

Sanofi shares rose as much as 2.6% and were up 0.9% by 0953 GMT.

“Given widespread niggling doubts the BOREAS readout would not be replicated, these…headlines should be well received,” analysts at Jefferies said.

Sanofi said it would file its request with the Food and Drug Administration (FDA) by the end of the year. The European Union’s drug regulator is already working on a similar request based on the BOREAS data.

Using Dupixent for COPD could add billions to the French drugmaker’s growth prospects. It would, however, also increase its already heavy reliance on the drug which is currently used to treat eczema, asthma and other inflammatory conditions.

Sanofi’s stock plunged at the end of October, wiping 20 billion euros off its market value, after it abandoned its 2025 profit target under a plan to list its consumer healthcare business and spend more money on developing innovative drugs.

The company has been discussing with major watchdogs across the world whether the BOREAS results were substantial enough to support a regulatory review and what role the second trial would play in reviews.

Sanofi has previously said it expects peak annual sales of Dupixent of more than 13 billion euros ($14.2 billion) but analysts have forecast on average that revenue would be well above that in 2025 and at around 18 billion euros in 2027.

Sanofi said about 300,000 people in the United Sates, have uncontrolled COPD that is characterised by an inflammation known as type 2, the focus of the two trials.

AstraZeneca, a maker of established inhalers to ease the lung disease, said in April it would spend about $450 million on a factory for devices in China to serve a major COPD market.

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