Drug development company Heat Biologics Inc. wants to sell 12 million shares to its existing shareholders to raise money for clinical trials and its business operations, according to a filing Tuesday with the Securities and Exchange Commission.

At its maximum, the stock sale would raise $11.2 million.

The biopharmaceutical company estimates net proceeds from this rights offering to be approximately $8.1 million, after expenses of nearly $900,000.

The rights offering will expire if not exercised by 5 p.m. EST on Nov. 8.

Heat Biologics develops drugs designed to activate a patient’s immune system against cancer.

The Durham-based company designs off-the-shelf ImPACT therapeutic vaccines that combat various cancers and infectious diseases.

Heat is currently conducting a separate clinical trial working to treat non-muscle invasive bladder cancer.

Heat Biologics shares dropped 4.53 percent, closing at 71.6 cents for the day.