Interferon alpha maintenance therapy in myeloma can extend the duration of the response achieved with chemotherapy (high dose-autotransplantation) by approximately 12-15 months. However relapse of the disease will eventually occur. The drug has not been shown to prolong the survival of the patients. Tolerance to the drug is a problem as it can cause depression, flu-like symptoms, drop in blood counts.If your father has had a good response to chemotherapy and is tolerating the interferon well, I would suggest he continue interferon indefinitely until relapse. If he has not had a stem cell transplant, he should do so, or atleast have stem cells collected as prolonged therapy with interferon may adversely affect stem cell collection. I am aware that Tata hospital in Bombay and AIIMS in Delhi are doing stem cell collections and transplants. Good Luck!