Filed Pursuant to Rule 425

Under the Securities Act of 1933

And Deemed Filed Pursuant to Rule 14a-12

Under the Securities Exchange Act of 1934

Filed by NPS Pharmaceuticals, Inc.

Subject Company: NPS Pharmaceuticals, Inc.

Enzon Pharmaceuticals, Inc.

Commission File No. 000-23272

The following materials were used by executives of NPS Pharmaceuticals, Inc. (“NPS”) in connection with the announcement of the proposed business combination between NPS and Enzon Pharmaceuticals, Inc. (“Enzon”).