Galena Biopharma said its breast cancer vaccine received a patent granting it exclusivity until 2028, sending its shares up as much as 35 percent.
The vaccine, NeuVax, gives immunity against the relapse of breast cancer in patients who have low-to-intermediate levels of HER2 -- a protein that can affect the growth of cancer cells.
NeuVax is being tested in a late-stage study under a special protocol assessment agreement with the U.S. Food and Drug Administration.
Once approved, it will be administered as an injection once a month for six months, followed by a booster injection once every six months.
According to the National Cancer Institute, more than 230,000 women in the United States are diagnosed with breast cancer annually, the company said.
Portland, Oregon-based Galena's shares were up 19 percent at $2.04 in morning trading on Wednesday. The stock, which touched a near four-month high of $2.30 earlier, was one of the top gainers on the Nasdaq.
(Reporting by Balaji Sridharan in Bangalore; Editing by Maju Samuel)