Enzon Pharmaceuticals, Inc. announced plans to spin off its biotechnology business into an independent company focusing on the development of cancer treatments. Enzon will fund the new company with $150 million, which is expected to provide two to three years of R&D activity. The transaction, which is subject to approval from Enzon’s board of directors, is expected to close in the fourth quarter.     Jeffrey H. Buchalter, Enzon’s chief executive officer, will head the new comp...