Aug 12 (Reuters) - Novartis failed to convince

a Delaware federal court to block generic drugmaker MSN

Pharmaceuticals from launching its own version of Novartis'

blockbuster heart-failure drug Entresto, according to a court

decision issued on Monday.

U.S. District Judge Richard Andrews ruled that Novartis'

chance of winning its patent-infringement lawsuit challenging

the generic was too low to justify halting MSN's launch.

However, he temporarily ordered MSN not to sell the drug while

Novartis appeals to the U.S. Court of Appeals for the Federal

Circuit.

Entresto is Switzerland-based Novartis' best-selling drug,

earning the company more than $6 billion in revenue last year.

MSN's version of Entresto was approved by the U.S. Food and Drug

Administration last month and would be the first U.S. generic of

the drug.

Spokespeople for Novartis and MSN did not immediately

respond to requests for comment on the decision.

Novartis sued MSN and others seeking to launch Entresto

generics in 2022 for infringing a patent that expires in 2026.

It asked the court on Aug. 2 for a preliminary injunction

blocking MSN from launching its generic, which was approved by

the FDA on July 24.

Andrews ruled on Monday that Novartis was not likely enough

to win on its infringement claims to justify the injunction. The

judge also rejected Novartis' argument that a ruling against the

company would cause "irreparable harm" by triggering a wave of

generic Entresto launches by other drugmakers.

Andrews placed a three-day hold on the case while Novartis

appeals to the Federal Circuit.

Novartis has separately asked a Washington, D.C. district

court to block MSN's launch as part of a challenge to the FDA's

decision to approve the generic. The Washington court has not

yet ruled on Novartis' request.