Daniel O'Day, the CEO of Roche's pharmaceuticals unit declined to comment on market rumors that the Swiss drug maker is about to bid for Alexion, but told CNBC that one of the key strategies for the company is to look for new drugs that could be incorporated into its portfolio.
"We don't comment on any market rumors, so I cannot speak on any specific companies. What I will say is our business is really focused on innovation and science," O'Day told CNBC.
"More than half of our portfolio of drugs have some form of partnership and we think that outside innovation complements well that inside innovation and drives our overall business."
Roche has been seeking financing for a potential bid for Alexion, according to Reuters, which would mark a shift into treatments for rare diseases as well as the cancer drugs it is currently known for.
(Read more: Roche sales beat forecasts despite pricing pressure)
Roche reported strong sales of its top three drugs and new expensive breast cancer treatments as it posted a bigger-than-expected rise in first-half core earnings of 10 percent. Shares rose 1 percent on Thursday morning.
The world's largest maker of cancer drugs said first-half sales rose 4 percent to 23.295 billion Swiss francs ($24.91 billion), generating core earnings per share (EPS) of 7.58 Swiss francs, up 10 percent.
Analysts on average had forecast sales of 23.293 billion francs and core EPS of 7.35 Swiss francs in a Reuters poll.
Sales of its top-three cancer medicines - Rituxan, Herceptin and Avastin - helped offset a weaker performance for its hepatitis drug Pegasys.
(Read more: UnitedHealth tops estimates, narrows outlook)
Roche also reported strong sales of its new breast cancer drugs, Perjeta and Kadcyla, which it plans to use in combination with its third-best seller Herceptin. Sales of the three drugs grew 11 percent to 3.3 billion Swiss francs in the first half.
The Basel-based firm expects full-year sales to grow in line with 2012 when they rose 7 percent, and core earnings to rise more than revenues. It also said it expected to further increase its dividend in 2013.
-- Reuters contributed to this report