CD95 predicts responsiveness to tretinoin in acute promyelocytic leukemia

We describe a predictive marker (CD95) for the responsiveness to tretinoin (RA) in acute promyelocytic leukemia (APL). Functional CD95 expression during RA treatment have been observed only in those patients who responded to RA. Expression of CD95 (Fas antigen), which plays a major role in apoptosis, was determined by fluorescence activated cell sorter (FACS) analysis. APL cases in which no enhancement of CD95 expression was observed showed no response to RA and did not obtain complete remission. We propose that CD95 can predict the clinical response to RA probably due to differentiation.