The agency has bagged the public affairs and PR account for Humira, an anti-inflammatory treatment for rheumatoid arthritis.
The brief is thought to be worth upwards of £300,000 a year and had been with WS for six years. Other agencies pitching are believed to be Just Health, Hanover and Weber Shandwick.
Humira is believed to be the world’s best-selling medicine, and analysts predict global sales will surge past $10bn (£6.2bn) in 2013. It is a biologic therapy, which means it mimics the effects of substances made by the body’s immune system.
The win is a significant one for Luther Pendragon’s health team. Its health portfolio includes the ABPI, Bristol-Myers Squibb and the Royal Pharmaceutical Society.
Luther Pendragon MD Simon Whale, Weber Shandwick and Abbott Laboratories all declined to comment.
WS won the business in 2006 from Fleishman-Hillard, which had been forced to relinquish it because of a conflict of interest with a UCB Pharma product, Cimzia.
Humira has many applications. In the US, it has been approved for use against moderate-to-severe ulcerative colitis in adults since September.
Abbott is also talking with MSLGroup in the US about global disease education work for Humira related to its use in cases of rheumatoid arthritis and psoriasis.
Abbott Laboratories will split into two separate trading entities in January.