Shares of Arrowhead Pharmaceuticals (ARWR) - Get Arrowhead Pharmaceuticals, Inc. Report were up 4% in premarket trading Thursday. Earlier this week brought word of a minority investor in the Pasadena, Calif.-based company. Silence Therapeutics, based in London, announced in a Jan. 9 statement that it has acquired a 8.4% stake in Arrowhead for $9.6 million. In a separate announcement on Jan. 9, Pasadena, Calif.-based Arrowhead said Silence bought the shares in the open market and Arrowhead was advised of the stake purchase just before Silence's announcement. Arrowhead said there have been no talks about any potential transaction between the two firms.

Lexicon Pharmaceuticals (LXRX) - Get Lexicon Pharmaceuticals, Inc. Report shares were up 3.8% on the heels of the company's presentation Wednesday at the 35th Annual J.P. Morgan Healthcare Conference.

Shares of Tesaro (TSRO) - Get TESARO, Inc. Report were down 3% after the company's Wednesday announcement that the U.S. Food and Drug Administration has issued a complete response letter on the rolapitant IV new drug application for the prevention of delayed nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy. 

The Waltham, Mass.-based oncology-focused biopharmaceutical company said the FDA's letter did not identify concerns associated with the the safety or efficacy of rolapitant IV or request additional clinical studies. Tesaro said the FDA requested additional information about the in vitro method used to show comparability of drug product produced at the two proposed commercial manufacturers for rolapitant IV that were included in the NDA. The company said it is working to provide the requested information.

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