Endocyte shares opened about 50 percent higher on Thursday after Swiss drugmaker Novartis agreed to buy the U.S.-based biopharmaceutical company for $2.1 billion.

Focusing on developing targeted therapeutics, Endocyte expands Novartis' platform with "both a potential near-term product launch and early-stage clinical development programs," Novartis said in a press release.

Novartis also raised its full-year sales outlook, citing growing revenue from its Cosentyx psoriasis and arthritis drug as well as the performance of its heart failure medicine Entresto, whose third-quarter sales more than doubled.

Novartis now expects sales to grow in the mid-single-digit percentage range at constant currencies, up from its previous forecast of low-to-mid-single-digit percentage rates.

Shares of Novartis were over 1.5 percent higher during mid-morning deals on Thursday.

"We are very pleased with how the innovative medicines business is performing, we are seeing strong growth on our key growth drivers Entresto and Cosentyx as well as across our oncology portfolio," Vasant Narasimhan, CEO of Novartis, told CNBC's "Squawk Box Europe" on Thursday.

Third-quarter core net income rose 2 percent to $3.1 billion, compared to the average analyst forecast of $3 billion in a Reuters poll. Sales rose 3 percent to $12.78 billion, compared to the average forecast of $12.84 billion in the poll.