Nektar Therapeutics ( NKTR - Get Report) on Monday named Howard W. Robin as its new president and chief executive, effective Jan. 15. Robin, 53, replaces Howard Chess, who has been acting president and CEO since March following the retirement of Ajit Gill. Chess will remain as chairman of the medical-device company. Nektar is known best as Pfizer's ( PFE - Get Report) partner for the inhaled insulin Exubera. For the past five years, Robin had been president and CEO of Sirna Therapeutics, a biotechnology company that was just purchased by Merck ( MRK). Before joing Sirna, Robin spent 20 years at Berlex Laboratories, the U.S. subsidiary of the German drugmaker Schering AG.