ROCKVILLE, Md. (AP) -- Nabi Biopharmaceuticals said Monday that its experimental anti-smoking vaccine NicVAX did not meet its main goal in a late-stage test, sending the company's shares plunging.The company said about 11 percent of patients who were received a dummy shot were able to quit smoking, and patients who were treated with NicVAX quit at a similar rate. Nabi said it is evaluating the data and waiting for results from a second late-stage study."We are clearly surprised and deeply disappointed with the results of this first NicVAX Phase III trial," said President and CEO Raafat Fahim.The company's stock dropped $3.93, or 70 percent, to $1.69 in midday trading.The yearlong study involved 1,000 patients. They were considered to have quit if they had not smoked a cigarette in the last 16 weeks of the study. Quitting was self-reported by patients and also measured biologically.NicVAX is intended to train the immune system to make antibodies that will attach themselves to nicotine. The goal is to keep the nicotine molecules from reaching the brain so people can quit smoking and not start again.In 2010, Nabi entered a partnership with British drugmaker GlaxoSmithKline PLC. Nabi could get more than $500 million from that agreement if NicVAX is approved. Monday's results dimmed those prospects.Shares of GlaxoSmithKline slipped 46 cents to $42.82.