Rational targeting in acute promyelocytic leukemia

Acute promyelocytic leukemia (ARL) is characterized by the nearly homogeneous expression of the fusion oncogenic protein PML-RARalpha and the testis-specific cyclin A1 protein, which are implicated in its pathogenesis. PML-RARalpha binds all-trans retinoic acid with high affinity inducing granulocytic differentiation and remission. Current approaches with high doses of single or combined all-trans retinoic acid and chemotherapeutic agents, though relatively efficacious in the beginning, are highly toxic with severe side-effects (retinoic acid syndrome) and are followed by relapse in a high proportion of patients. Here it is proposed that targeting APL with low levels of all-trans retinoic acid combined with small molecule inhibitors of cyclin-dependent kinases may have the potential to be equally or more efficacious as any of the current single or combined agent approaches, affording reduced toxicity and relapse rates.