Molecular Biology of Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) is a subtype of human acute myeloid leukemia characterized by a differentiation block at the promyelocytic stage of myeloid differentiation (Bennet et al., 1976). The differentiation block is the most distinctive biological feature of the APL phenotype because the promyelocytic blasts have a modest proliferative rate (Raza et al., 1987, 1992); and the release of the block and terminal differentiation obtained by al- trans retinoic acid (ATRA) correlates in vivo with complete hematologic remission in the great majority of APL patients (Huang et al., 1988; Castaigne et al., 1990; Chomienne et al., 1990; Warrel et al., 1991; Lo Coco et al., 1992a; see Chapter 19, this volume). This effect of ATRA makes APL the best example of the effectiveness of differentiation therapy. Although attempts to treat other hematologic neoplastic disorders with differentiation therapy have led in the past to disappointing results (Degos et al., 1985; Cheson et al., 1986; Sawyers et al., 1991; Young et al., 1993), this therapeutic strategy now provides a novel approach for the control of neoplastic cell growth. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.