NEW YORK, June 24 (Reuters) - Cigna ( CI ) sued Bristol

Myers Squibb ( BMY ) on Tuesday, accusing the drugmaker of

violating U.S. antitrust law by keeping generic versions of its

blockbuster multiple myeloma drug Pomalyst off the market so it

can retain a monopoly.

In a complaint filed in Manhattan federal court, Cigna ( CI )

said Bristol Myers' Celgene unit filed sham lawsuits to protect

its patents for Pomalyst, and paid several makers of generic

versions of the drug to end challenges to the patents.

The Bloomfield, Connecticut-based insurer also said

Celgene failed to disclose to the U.S. Patent and Trademark

Office that a Boston doctor had already obtained a patent for

pomalidomide, the chemical name for Pomalyst, to treat multiple

myeloma.

By having "willfully maintained monopoly power" over

brand name and generic Pomalyst, Bristol Myers caused purchasers

such as Cigna ( CI ) to overpay by "many hundreds of millions, if not

billions, of dollars," the complaint said.

Cigna ( CI ) is seeking unspecified triple damages from Bristol

Myers, which is based in Princeton, New Jersey.

Bristol Myers did not immediately respond to requests

for comment.

The company's U.S. sales of the drug, which is also sold

under the name Imnovid, totaled $2.7 billion last year and $537

million in the first three months of 2025.