WASHINGTON, Dec 29 (Reuters) - Vanda Pharmaceuticals Inc. may raise up to $75 million in an initial public offering of stock, according to a regulatory filing on Thursday. The lead underwriters for the offering are expected to be JPMorgan, Banc of America Securities LLC and Thomas Weisel Partners LLC , according to the filing with the U.S. Securities and Exchange Commission. Price and share terms have not yet been set.