CONVERSION OF INTERFERON-INDUCED, LONG-TERM CYTOGENETIC REMISSIONS INCHRONIC MYELOGENOUS LEUKEMIA TO POLYMERASE-CHAIN-REACTION NEGATIVITY

Purpose: Interferon alfa (IFN-alpha) induces complete cytogenetic remi ssion in a significant minority of patients with chronic myelogenous l eukemia (CML). To date, use of the polymerase chain reaction (PCR) has suggested that residual disease is present in virtually all these ind ividuals at median follow-up intervals of approximately 1 year after i nitial achievement of cytogenetic remission. We sought to determine th e PCR status of CML patients with very long continuous complete cytoge netic remissions on IFN-alpha. patients and Methods: Blood and/or bone marrow samples from 18 CML patients maintained in continuous cytogene tic remission by IFN-alpha for at least 1 year were studied for residu al BCR-ABL mRNA by single-step reverse-transcriptase (RT)-PCR methodol ogy, followed by detection of the amplification product by the hybridi zation protection assay (HPA). Results: Ten of 18 patients showed RT-P CR negativity for BCR-ABL. The median duration of continuous complete cytogenetic remission at the time of sample collection for the negativ e patients was 42 months versus 21 months for the patients whose tests remained positive (P = .05). Conclusion: Very long-term follow-up of IFN-alpha-treated CML patients in continuous complete cytogenetic remi ssion is associated with a decrease in the number of BCR-ABL transcrip ts to a level below that detectable by the RT-PCR assay used in this s tudy. (C) 1998 by American Society of Clinical Oncology.