Re-induction of complete remission with a new synthetic retinoid, Am-80, for relapse of acute promyelocytic leukaemia previously treated with all-trans retinoic acid

Summary. Two patients with relapsed acute promyelocyticleukaemia previously treated with all- trans retinoic acid(ATRA), were treated with a new synthetic retinoid, Am-80.In both patients pancytopenia gradually resolved without anincrease in leukaemic cells, and differentiation of leukaemiccells was observed morphologically in bone marrow. With-out the use of anti-leukaemic agents, both cases achievedcomplete remission (CR) on days 52 and 38 of treatment,respectively. On the day of CR, PML gene rearrangement andthe t(15;17) translocation disappeared, though PML-RAR achimaeric messenger RNA was still detected by reversetranscriptase polymerase chain reaction. Both patients thenreceived conventional chemotherapy for consolidation ofCR. These clinical experiences suggest that Am-80 may bean active agent for APL patients who have relapsed fromATRA-induced remission. Keywords: Am-80, acute promyelocytic leukaemia, all- trans retinoic acid, PML-RARa chimaeric messenger RNA,differentiation therapy.All-