Progenics Pharmaceuticals, a pharmaceutical firm researching the development of an AIDS virus vaccine, expanded its corporate headquarters. The firm is increasing the amount of space it occupies in the Landmark at Eastview at 777 Old Saw Mill River Road in Tarrytown, NY, by an additional 38,000 square feet. Progenics will take occupancy of the new space, which includes office and laboratory space, during the next six months. It will occupy a total of 80,000 square feet.