A judge has ruled in favor of Illumina Inc. in its acquisition of Grail Inc., dealing a blow to the U.S. Federal Trade Commission's efforts to unwind the multi-billion-dollar deal, the Wall Street Journal reported on Thursday, citing people familiar with the matter.

The FTC had sought to stop Illumina's $7.1 billion proposed acquisition of cancer detection test maker Grail, alleging it would harm innovation and boost prices.

Illumina and Grail did not immediately respond to Reuters requests for comment.