Isis Pharmaceuticals Inc. (ISIS) swung to a first-quarter profit as revenue generated by its partnership with Genzyme Corp. (GENZ) and a gain from selling Isis Biosciences boosted results.

The drug-therapies developer sold the remaining 81% stake in the biosciences diagnostic unit in January to Abbott Laboratories (ABT). Isis develops drug therapies based on antisense technology, in which drugs attach themselves to strands of a molecule known as RNA to block them from producing disease-causing proteins. Its lead drug is cholesterol fighter mipomersen, leased to Genzyme.

Isis reported a profit of $171.8 million, or $1.57 a share, reversing a year-earlier loss of $5.8 million, or 6 cents a share. The company received $175 million during the quarter from the divestiture.

Revenue soared 72% to $31.6 million, as research-and-development revenue jumped 68% and licensing and royalty revenue more than doubled.

Analysts surveyed by Thomson Reuters were expecting a profit of $1.70 a share on revenue of $30 million, according to Thomson Reuters.

The rise in Genzyme-partnership revenue reflected the year-ago period's inclusion of only revenue from amortization of the stock premium.

Isis shares closed Wednesday at $15.24 and were inactive premarket.

-By Mike Barris, Dow Jones Newswires; 201-938-5658; mike.barris@dowjones.com