Use of alpha-2a-interferon to treat cytogenetic relapse of chronic myeloid leukemia after marrow transplantation.

Fourteen patients with cytogenetic relapse of chronic myeloid leukemia (CML) after transplantation with unmanipulated bone marrow were treated with alpha-2a-interferon. There were eight men and six women, median age, 33 years. Twelve patients received marrow from a related allogeneic donor and two received marrow from a syngeneic donor. The median percentage of Ph-positive metaphases at the time of starting interferon was 55% (10% to 87%). Daily interferon was started at a dose of 1 to 3 x 10(6) U/M2/d, depending on initial blood counts and was adjusted as tolerated to maintain the white blood count in the range of 2,000 to 3,000/microL and the platelet count greater than 60,000/microL. After a stable cytogenetic remission was achieved, the interferon dose was decreased to a maintenance level. Twelve patients achieved a complete cytogenetic remission on at least one occasion. Median time to achieve a complete cytogenetic remission was 7.5 months (range, 1.5 to 12). Eight patients remain in cytogenetic remission for 10+ to 54+ months from the time of first documented remission. After complete cytogenetic remission was established, nine patients were tested for the presence of the mRNA transcript of the bcr/abl fusion gene by polymerase chain reaction (PCR) testing. Four patients were PCR-negative on at least one occasion: two patients were PCR-negative on a single occasion; one patient had serial tests, which were PCR-negative; and one patient had serial PCR-negative peripheral blood tests with a single PCR-positive bone marrow obtained concurrently with a negative peripheral blood test. Median follow-up time for all patients is 44 months (range, 20 to 64). Interferon was generally well tolerated; only one responding patient was unable to continue interferon because of toxicity. Interferon induces durable cytogenetic remissions in a significant proportion (57%) of patients with cytogenetic relapse following bone marrow transplantation (BMT) without causing life-threatening toxicities.