All-trans retinoic acid in the treatment of acute promyelocytic leukaemia.

All-trans-retinoic acid (ATRA) is known to induce differentiation of promyelocytes in vitro and also to induce remission of acute promyelocytic leukaemia in vivo. We treated 11 patients with poor prognosis acute promyelocytic leukaemia (APL) with ATRA and obtained seven complete and one partial remission. Remissions took one to three months to achieve and were associated with adverse effects including dry skin and bone pain. In eight patients the white cell count rose above 20 x 10(9)/L within the first ten days of retinoic acid treatment and this was associated with the development of pulmonary leukostasis in three patients which was fatal in one. Another two patients died of intracranial haemorrhage also within the first ten days. ATRA is a promising new agent in the induction therapy of this particular category of acute leukaemia.